Tropical Medicine and Health

Tropical Medicine
and Health2006

Vol.34
No.02
JUNE 2006

ISSN 1348-8945

Vol.34 No.02 JUNE

ISSN 1348-8945【CONTENTS】
Letter to the Editor
Proactive plan to help contain pandemic influenza in Asia
Yamamoto T and Crump A

75

Original articles
Cryopreservation of newborn and muscle-stage larvae of Trichinella nativa
Lizhi H, Masutani Y and Uga S

77

The Roles of Western biomedicine and folk medicine in rural Solomon Islands: A
quantitative analysis of villagers’ response to illness
Furusawa T

83

Vol.34 No.02 JUNE 2006

Tropical Medicine
and HealthJAPANESE SOCIETY OF TROPICAL MEDICINEJAPANESE SOCIETY OF
TROPICAL MEDICINE

Trop.Med.Health日本熱帯医学会表紙!−" ＣＭＹＫ 稲 平島 〃

背は２mm
（決）

Tropical Medicine and Health

Tropical Medicine
and Health2006

Vol.34
No.02
JUNE 2006

ISSN 1348-8945

Vol.34 No.02 JUNE

ISSN 1348-8945【CONTENTS】
Letter to the Editor
Proactive plan to help contain pandemic influenza in Asia
Yamamoto T and Crump A

75

Original articles
Cryopreservation of newborn and muscle-stage larvae of Trichinella nativa
Lizhi H, Masutani Y and Uga S

77

The Roles of Western biomedicine and folk medicine in rural Solomon Islands: A
quantitative analysis of villagers’ response to illness
Furusawa T

83

Vol.34 No.02 JUNE 2006

Tropical Medicine
and HealthJAPANESE SOCIETY OF TROPICAL MEDICINEJAPANESE SOCIETY OF
TROPICAL MEDICINE

Trop.Med.Health日本熱帯医学会表紙!−" ＣＭＹＫ 稲 平島 〃

背は２mm
（決）

Tropical Medicine and Health Vol. 34 No. 2, 2006, pp. 75-76
Copyright! 2006 by The Japanese Society of Tropical Medicine

７５Letter to the Editor
Dear Sir

Proactive plan to help contain pandemic influenza in Asia
Received 28, June, 2006

Ferguson and colleagues’ model of influenza transmission[1] indicates that elimination of a nascent influenza pandemic might be feasible using a combination of geographically-targeted antiviral prophylaxis[2](particularly neuraminidase inhibitors), together with social distancing measures, and that the speed of distribution of antivirals will be crucial.
Participants at the Japan-WHO Joint meeting on Early Response to Potential Influenza Pandemic, heldin Tokyo in January[3], reached the same conclusion. In addition, there was consensus that early containment measures would be essential to help slow the spread of pandemic influenza, helping to buy time to develop an effective vaccine against any newly-evolved influenza strains.
In Asia, where more than 80% of human Avian flu cases have so far been reported, the level of preparedness with respect to antivirals to contain a potential influenza pandemic is generally less than adequate.
Stocks of drugs for containment and treatment purposes in Indonesia total less than 20,000 courses, Cambodia and Lao PDR less than 200, and Myanmar almost nil, whereas stockpiles in Thailand and Singapore
are approximately 100,000 and 700,000 respectively. Moreover, it is likely that there will be significant logistical delay in antivirals currently stockpiled by WHO in Europe and North America for global containment purposes being mobilised and distributed in Asia.
To help contain any regional Avian flu pandemic threat, Japan has proactively decided to provide
500,000 courses of anti-flu drugs to Association of South East Asian Nations (ASEAN) countries with theintention of storing them in the international airport in Singapore, where they will be available for rapid distribution. Should an outbreak occur, following guidance from WHO, the Government of Japan, the affected
country, and the ASEAN secretariat will coordinate delivery of antivirals to the international airport nearest
to the location of the outbreak, ideally within 12 hours. This should effectively fill the gap until antiviraldrugs stockpiled by WHO became available. A Plan of Action is currently being devised to ensure rapid
deployment of the stockpile when the need arises. Indicative of the nation’s intention to fully tackle Avian
Flu, according to a recent World Bank report, Japan remains one of only three nations to fully commit
funds pledged at the Avian Flu funding meeting in Beijing in January, disbursing $158 million thus far to avariety of countries and organizations at the regional and global levels. The European Union’s recent failure to implement a plan to stockpile Tamiflu indicates that Europe’s commitment to Avian Flu pandemic
preparedness may be on the wane.
References
1. Ferguson NM, et al. Strategies for containing an emerging influenza pandemic in Southeast Asia. Nature
2005; 437: 209-14.
2. Longini IM, Halloran ME, Nizan A, et al. Containing pandemic influenza with antiviral agents. Am. J.
Epidemiol. 2004; 159: 623-633.
3. Ministry of Foreign Affairs Japan.
http://www.mofa.go.jp/policy/health_c/poultry/meet0601.pdf
Authors:
Taro Yamamoto

７
６

Deputy Director
Aid planning Division
Economic Cooperation Bureau
Ministry of Foreign Affairs
2-2-1 Kasumigaseki
ChiyodaTokyo 100-8919
JAPAN
Andy Crump
Kitasato Institute5-9-1 Shirokane
Minato Ku
Tokyo 108-8642
JAPANTropical Medicine and Health Vol. 34 No. 2, 2006, pp. 77-82
Copyright! 2006 by The Japanese Society of Tropical Medicine

７
７

CRYOPRESERVATION OF NEWBORN AND MUSCLE-STAGELARVAE OF TRICHINELLA NATIVA
Hu Lizhi１, Yuki Masutani２ and Shoji Uga１
Accepted 17, May, 2006

Abstract: We examined the basic conditions for cryopreservation of newborn and muscle-stage larvae of Trichinella nativa. Two types of cryoprotectants were examined: dimethyl sulfoxide and glycerol. For cryopreservation of newborn larvae, dimethyl sulfoxide had a cryoprotective effect, and a maximum survival of 96% was obtained under conditions of 10% dimethyl sulfoxide and 30 min equilibration. Muscle-stage larvae, on the other
hand, demonstrated a relatively high survival rate (approximately 80%) with 25% glycerol and three hours equilibration regardless of freezing rate. The infectivity of cryopreserved newborn and muscle-stage larvae was examined using different infection methods: direct injection into the abdominal cavity in the former, and either oral infection or direct injection into the duodenum in the later. Cryopreserved newborn larvae showed infectivity to all
the subjected mice. By contrast, muscle-stage larvae did not show any infection when infected orally, but one
mouse was positive when the larvae were injected directly into the duodenum.
Keywords: cryopreservation; Trichinella nativa; cryoprotectant; freezing

INTRODUCTION
Trichinella spp. is a nematode parasite, the larvae of
which are known to encyst in the muscles of mammals, including humans. There are many species of Trichinella, allof which can cause the food-borne illness trichinellosis ortrichinosis. This illness occurs when raw or improperly
cooked meat containing the larvae of the parasite is consumed by mammals, including humans. Clinical manifestations of infection vary from asymptomatic to moderate gastrointestinal distress to cardiac and neurological complications and possibly even death [18]. Consequently, manylaboratories are currently investigating the biological andbiochemical characteristics of a large number of Trichinella
spp. isolates using laboratory animals. However, conventional methods for the propagation and preservation of parasites in vivo and in vitro have a number of limitations, including the need for labor, bacterial/fungal contamination,and changes in the original biological and metabolic characteristics [7, 15, 21]. All of these disadvantages are considerably reduced by cryopreservation, which to date has been
applied to several species of parasites.
Some protozoan parasites such as Trypanosoma spp.
and Plasmodium spp. have been successfully cryopreservedwith high survival rates [5, 15]. These single cells respondin a relatively uniform way to physical and chemical
stresses during the freezing procedures and can be frozen
12easily without cryoprotectants or precise control of freezing
rate [5, 15, 22]. On the contrary, in multicellular systems
like helminths, the response to cryopreservation protocols is
not uniform, thus making successful cryopreservation difficult to achieve. Although many studies on the cryopreservation of helminthic parasites have been conducted [7, 10,14], only a few species, mainly nematodes, have been successfully cryopreserved, i.e., microfilariae of Dirofilaria corynodes, Brugia malayi, and Wuchereria bancrofti [14];first-stage larvae of Haemonchus contortus, Trichostrongylus colubriformis, and Ostertagia circumcincta [7]; secondstage larvae of Toxocara canis [20]; and various staged larvae of Trichinella spp. [11, 19].
Pozio et al . (1988) [19] carried out cryopreservation of
newborn larvae (NBL) and muscle-stage larvae (MSL) ofdifferent Trichinella spp.. Although approximately 80% of
the NBL were found to be motile after thawing, only 8% of
T. spiralis, 6% of T. nativa, and 1% of T. pseudospiralis
were infective to mice. On the contrary, none of the MSL
were infective to mice despite motility rates of 80 ± 7%.
Similarly, Genan and James (1988) [11] reported cryopreservation of Trichinella spp. using liquid nitrogen. They
pre-treated the MSL with 10% dog’s bile at 37°
C for onehour and then adopted a freezing rate of 5,100°
C min−１. Of
the MSL frozen, 80% were motile, and of these, 1.1 ±
0.4% grew to adults when inoculated in mice. Pozio et al .
(1988) [19] reported that cryopreservation of adult worms

Department of Medical Technology, Faculty of Health Sciences, Kobe University School of Medicine, Kobe 654-0142, Japan
Department of Organ Transplantation, National Cardio Vascular Center, Osaka 565-0873, Japan (present address)

７
８

always failed and that motile NBL were frequently observed beside broken female worms damaged during freezing.
Although numerous authors have studied the cryopreservation of parasites, studies related to Trichinella spp.
are limited [11, 19]. Therefore, the fundamental conditions
needed for cryopreservation remain relatively unknown. In
the present study, we examine the basic conditions (the typeand concentration of cryoprotectant, equilibration time, andfreezing rate) required for cryopreservation of Trichinella
nativa.

MATERIALS AND METHODS
Preparation of parasites
We used T. nativa parasites kindly supplied by the Department of Parasitology, Gifu University School of Medicine, Japan. The parasites were maintained using ICR mice,and the NBL and MSL were subjected to cryopreservation.
To obtain NBL, the ICR mice were infected orally with
300―400 MSL. On the sixth day post infection, each mouse
was sacrificed and then the entire small intestine was removed and slit longitudinally to recover the adult worms.
The recovered adult worms were washed twice in Medium
199 (Gibco, Tokyo, Japan) containing horse serum 10%(v/v) (100 UI/ml penicillin; 100 mg/ml streptomycin; 2
mg/ml liquid fungizone). They were then placed in a 10-ml
petri dish with the same volume of culture medium and incubated at 37°
C in a CO２ incubator. After 48 hrs, NBL wererecoverable from the culture medium. The culture medium
containing NBL was washed in sterile warm phosphatebuffered saline (PBS) then centrifuged at 450 × g for 10
min at room temperature.
To obtain MSL, the muscles of infected mice were
subjected to artificial digestion for one hour using digestive
solution (1,000 ml distilled water; 10 ml HCl; 1 g pepsin).
MSL were recovered and washed twice in PBS then treatedwith 0.25% cetyltrimethylammonium bromide (CTAB)(Gibco, Tokyo, Japan) or 10% dog’s bile in culture medium
at 37°C for one hour. They were then cultured in culture
medium as above for NBL.
Cryoprotectants
Two cryoprotectants were tested, namely, dimethyl
sulfoxide (Me２SO) (Wako, Osaka, Japan) and glycerol(Wako). The cryoprotectant was added to a 1.2-ml plastic
cryogenic vial (Wako) and adjusted to a final concentrationof 5―30% as appropriate for the different subcultures. The
entire mixture was then incubated at 37°
C for 0.25―3 hrs(equilibration).
Freezing and thawing
The freezing procedure used in this experiment was

based on Miyake et al . (2004) [16]. Briefly, a cryogenic
vial containing the T. nativa suspension was dipped in
99.5% alcohol. The freezing rate was then controlled byadding small pieces of dry ice to the alcohol. Freezing rates
C were 0.3, 1, and 3°
C min−１,of the NBL and MSL to ―40°
−１
C. The vials were thenfollowed by 3°
C min to ―70°
plunged into liquid nitrogen. The precise freezing rate at
this point is unknown. The seeding method was that reported by Miyake et al . (2004) [16]. Briefly, ice crystals(about 2 mm in diameter) obtained by freezing physiologiC.
cal saline were seeded in suspension at ―4°
The frozen suspension was thawed at a rate of 70°
C−１
min , which was obtained by keeping the suspension in awater bath at 37°
C for 1 min. The thawed larvae were thendiluted in PBS by 1:10.
Viability assessment
After thawing, the suspension was observed under alight microscope to check the viability of the NBL and
MSL. If thawed NBL showed the same active motility as
unfrozen NBL, the parasites were judged viable. In thecase of MSL, the cryopreserved larvae were classified into
two groups: normal and abnormal. Normal MSL showed
active motility without any damage to intestinal organs,
while abnormal MSL showed obvious damage to these organs despite their motility.
The infectivity of NBL and MSL were confirmed after
cryopreservation. NBL (3,000) were injected into the abdominal cavity of mice, and then on the 30th day post infection, the mice were sacrificed and examined for the presence of MSL. MSL (2,000), on the other hand, were given
to ICR mice per os or injected into the intestinal duodenumof laparotomized mice. On the 30th day post infection, themice were sacrificed and examined for the presence of MSL.

RESULTS
Cryopreservation of NBL
Table 1 shows the effects of cryoprotectant type andconcentration as well as equilibration time on the survival
rate of NBL after thawing. Of the two kinds of cryoprotectant examined, Me２SO had a higher protective effect thanglycerol. When the NBL suspension was kept at 37°
C for
30 min (equilibration) prior to freezing, the survival rate of
NBL after thawing was higher than that with other equilibration times. The concentration of Me２SO was also criticalfor survival with the maximum survival of 96% obtained
under conditions of 10% Me２SO and 30 min equilibration.
Cryopreservation of MSL
Table 2 shows the effects of cryoprotectant type andconcentration as well as freezing rate on the survival of
MSL after thawing. Glycerol had a higher protective effect７
９

Table 1. Effects of type, concentration, and equilibration time of cryoprotectants on survival rates of NBL
Type ofcryoprotectants

Equilibration
time (min)Concentration of cryoprotectants (%)
5
10
15

20

25

Me２SO

15
30
45
60

78±7
84±15
47±2
53±22

69±15
96±3
64±11
54±24

66±7
93±3
61±5
39±6

48±20
80±11
49±8
32±13

25±12
39±14
20±1
12±7

Glycerol

15
30
45
60

15±8
40±10
36±14
52±16

37±7
55±17
39±18
69±18

48±6
34±12
58±4
47±2

8±4
10±7
26±8
35±3

10±6
23±6
15±6
19±3

Cryoprotectants were added at 37°
C. After equilibration, the samples were cooled to ―40°
C at 1°C min−１ andC at 3°C min−１. Each experiment was performed three times.
to ―70°

Table 2. Effects of cryoprotectant and freezing rates on survival rates of MSL
Type ofcryoprotectants
Glycerol＊Survival
No.
%
66
45
81
49
123
65
147
82
147
79

Concentration of
cryoprotectants (%)
10
15
20
25
30

Freezing rate(°
C/min)
0.3

No. of MSL
examined
147
165
189
180
186

Glycerol＊

10
15
20
25
30

1

330
327
339
354
339

180
225
258
303
258

55
69
76
86
76

Glycerol＊

10
15
20
25
30

3

156
171
153
177
153

75
111
123
159
123

48
65
80
90
80

Me２SO†

5
10
15
20

1

273
261
300
255

21
39
39
38

8
15
13
15

＊

Equilibration time = three hours.
Equilibration was not performed.

†

than Me２SO; that is, a higher survival rate was obtainedwith glycerol at a concentration of 25% regardless of thefreezing rate used. Freezing rates of 0.3, 1, and 3°
C min−１resulted in maximum survival rates of 82, 86, and 90%, respectively, without significant differences (P > 0.05, students t-test).
Figure 1 shows the effects of pre-treatment on the survival rate of MSL after thawing. In this experiment, the following conditions were used: 25% of glycerol as a cryoprotectant, three hours equilibration at 37°
C, and a freezing rate
C. Relatively high surof 1°
C min−１ between 37 and ―40°
vival rates, approximately 80%, were obtained from boththe untreated and two pre-treated groups, without signifi-

cant differences (P > 0.05). However, when the appearanceof normal larvae was considered, rates differed among thethree groups: the bile-treated group showed the highest percentage of normal larvae (63%), while the CTAB-treatedand untreated groups showed 51 and 44%, respectively.
Infectivity of NBL and MSL after thawing
Of the five mice infected with cryopreserved NBL, allwere positive for MSL on the 30th day post infection. On
the other hand, mice orally infected with cryopreserved
MSL showed no infectivity regardless of pre-treatment of
the larvae. One infected mouse was obtained when MSL
were pre-treated with dog’s bile and infected directly into
the mouse duodenum after thawing (Table 3).

８０Abnormal

100

NormalSurvival（％）

80

60

40

20

0

Untreated

CTAB

Bile

Pre-treatment

Figure 1. Effect of pre-treatment on survival rates of
MSL.

DISCUSSION
Since the first successful cryopreservation of Plasmodium spp. in 1939, a number of parasite species have beensuccessfully cryopreserved, including protozoa such as
Toxoplasma gondii [1], Entamoeba histolytica [6], and Trypanosoma cruzi [5], as well as helminths such as trichostrongylidae [7], microfilariae of Dirofilaria corynodes andBrugia malayi [14], and Toxocara canis [20]. Someauthors have also reported cryopreservation of Trichinella
spp., although none have obtained satisfactory results [2-4,11, 19]. Infective MSL of T. spiralis have been recovered
C for 12 months [4],from polar bear muscle frozen at ―15°
C for 18 months [3], and arctic
wolf muscle frozen at ―10°
C for 14 months [2]. However, the preserfox frozen at ―15°
vation periods of these experiments were limited to several
months. In addition, when the parasites were preserved using laboratory animals such as mice and/or rats, the survival
period decreased. Cryopreservation of Trichinella spp. at
an ultra low temperature has been reported by Gegan andJames (1988) [11] and Pozio et al . (1988) [19]. Pozio et al.
(1988) [19] obtained infective NBL of both T. spiralis andT. nativa when the larvae were cryopreserved using 10%

Me２SO, but MSL cryopreserved using the same method did
not show any infectivity to mice. Similarly, Gegan andJames (1988) [11] reported that 80% of T. spiralis MSL
used in their cryopreservation study survived after thawing,
but infectivity of these larvae was extremely low. In ourstudy, on the other hand, not only NBL but also MSL of T.
nativa showed infectivity to mice after thawing, although
the survival rate of MSL was low. Our experiment therefore suggests that the infection method is also an importantfactor in confirming the infectivity of the larvae after thawing. Although we have cryopreserved muscle stage larvaeof T. spiralis, the survival rate after freezing was always
lower than that of T. nativa (data not shown). Therefore,
this paper represents the results obtained using T. nativa.
As reported by Pritchard et al . (1985) [17], CTABtreated larvae lose an excretory/secretory antigen that coats
the surface of their body, thus causing an decrease in thesusceptibility of these larvae to digestive juice. It seems
that a similar phenomenon arises in larvae treated with bile.
In the present experiment, we assumed that larvae introduced directly to the duodenum of the recipient mice would
not be affected by digestive juices.
In our study, Me２SO and glycerol were used as cryoprotectants and their effect on the survival of NBL and
MSL was investigated. Me２SO has been used as a cryoprotectant for the cryopreservation of many species of parasites[11, 14-16, 19, 20]. In the present study, the highest survival rate of NBL was obtained with 10% Me２SO. This result is similar to that of Pozio et al . (1988) [19] who reported that Me２SO at a concentration of 10% yielded 80%
motile NBL after thawing. On the other hand, Mutetwa andJames (1984) [15] reported that glycerol had similar cryoprotective effects as Me２SO. With both Me２SO and glycerol,the protective effect on frozen cells requires intracellularpermeation, and the difference between Me２SO and glycerolis the speed at which they permeate the cell: glycerol permeates more slowly than Me２SO. Therefore, equilibrationis thought to be necessary when glycerol is used as a cryoprotectant [15]. In our study, the duration of equilibration
for glycerol was three hours.

Table 3. Infectivity of cryopreserved MSL to mice
Infection method
Per osInjection＊＊

Pre-treatment

No. of MSL
infected

No. ofmouse used

No. of mouseshowing positive

Untreated
CTAB
Bile
Untreated
CTAB
Bile

3,000
3,000
3,000
2,000
2,000
2,000

5
2
2
1
3
2

0
0
0
0
0
1

Injected in the intestinal duodenum in laparotomized mouse.

８１

For MSL, in contrast to NBL, the most effective cryoprotectant was glycerol. Few reports have mentioned thatthe cytotoxicity of glycerol is less than that of Me２SO [11,16]. MSL have a more complicated cellular system thanNBL and therefore require a longer equilibration time forcryoprotectant penetration. This might explain why glycerol was more effective with MSL in the present study.
Moreover, the cytotoxic effect of glycerol was shown, forthe first time, to remain low even when exposed for a longer
period of time.
We also examined the effects of freezing rate on MSL
survival rates after cryopreservation. Ham and James(1983) [8] reported that the highest survival rate (95%) was
obtained with a freezing rate of 5°
C min−１ compared to 1, 2,−１
and 10°C min . In our study, the maximum survival rate of
90% was obtained at a freezing rate of 3°
C min−１, followed−１
C min−１. There wereby 86% at 1°
C min and 82% at 0.3°
no significant differences (P > 0.05) between survival rates
despite the different rates used, but the reason for this remains unknown. Therefore, further experiments to determine the optimum freezing rate are needed.
Permeability of cryoprotectants is often a critical factor
in the successful cryopreservation of a number of helminth
species. Schistosome schistosomula cannot be cryopreserved until the cercarial glycocalyx is lost [9], and for several nematode species, excystment of third-stage larvae isessential for survival during cryopreservation [12, 13]. In
the case of MSL, facilitating the penetration of cryoprotectants is also an important factor in obtaining high survival
rates [11]. Pritchard et al . (1985) [17] reported that the useof 0.25% CTAB at 37°
C for one hour to remove excretory/
secretory antigens can increase surface permeability. In addition, Gegan and James (1988) [11] reported that larvae
pre-treated with 10% dog’s bile at 37°
C for one hour can increase surface permeability. In our study, the effects of pretreatment with CTAB and bile were examined. When MSL
were pre-treated with CTAB and bile, the percentage of normal larvae was higher than with untreated larvae after thawing (Figure 1). In addition, infective MSL were also obtained in bile pre-treatment group (Table 3). From the results obtained, increasing cryoprotectant permeability toprevent damage during cryopreservation of MSL also seems
to be an important factor [11].
In summary, the basic conditions of cryopreservation(the type and concentration of cryoprotectant, equilibration
time, and freezing rate) of NBL and MSL of T. nativa were
examined. The cryopreservation of both larvae was possible in liquid nitrogen; however, the infectivity of the MSL
remained low even though that of the NBL was high. Further studies to improve the infectivity of MSL are therefore
required.

ACKNOWLEDGMENTS
We thank Dr. Takahashi and Dr. Wu (Department of
Parasitology, Gifu University School of Medicine, Japan)
who kindly provided Trichinella nativa. And Dr. Vachel
Gay Paller kindly checked the English manuscript.

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２
２．Weathersby AB, McCall JW. (1981): Cryopreservation of
Plasmodium gallinaceum Brumpt sporozoites for 16 years
at ―196°
C. Cryobiology, 18, 313-314.

Tropical Medicine and Health Vol. 34 No. 2, 2006, pp. 83-91
Copyright! 2006 by The Japanese Society of Tropical Medicine

８３

THE ROLES OF WESTERN BIOMEDICINE AND FOLK MEDICINEIN RURAL SOLOMON ISLANDS: A QUANTITATIVE ANALYSIS
OF VILLAGERS’ RESPONSE TO ILLNESS
Takuro Furusawa
Accepted 26, May, 2006

Abstract: This study aimed to explore factors determining treatment-seeking behaviors of villagers in a rural Roviana society of the Solomon Islands. Participants (n = 116) were interviewed every evening for 42 days about theoccurrence of illnesses and how they had been treated. The study period was divided into two: 22 days during
which a nurse was stationed in the village and 20 days when the nurse was absent. As the results show, nurse’s
presence had a negative effect on traditional folk medicine use (OR = 0.39, [95% CI: 0.21―0.72]). Fever or headache was treated more preferably with biomedicine (3.82 [1.81―8.07] or 6.75 [2.75―16.55], respectively), whereas
putuputu, an illness with an indigenous etiology, was treated with the latter (34.7 [3.13―384.41]). In addition, biomedicine was preferably used (7.72 [2.65―22.44]) for the treatment of severe illnesses. While folk medicine wasused in 40% of all ill person-days, it has likely been partly displaced by effective Western biomedicine. Still, somefolk medicine functioned as a culturally indispensable element in treating indigenous illnesses.
Keywords: Folk medicine, Biomedicine, Medical pluralism, International Health, Roviana, Solomon Islands

INTRODUCTION
Indigenous medical systems, hereafter “folk medicine,” have been developed in many societies with markedly
different characteristics [1, 2]. Folk medicine has undergone changes since coming under the influence of Europeans who introduced Western medicine and discouraged traditional folk medicine [3, 4, 5, 6, 7, 8, 9, 10]. Previous
studies in Oceania have reported the existence of medical
pluralism, which is defined as coexistence of different
medical systems in a single society [11]. For instance, in
Melanesian societies, traditional folk medicine is chosen to
cure indigenous illnesses or those thought to have supernatural causes, while Western biomedicine is used to treat
introduced illnesses and those with non-supernatural causes[4, 9, 12, 13]. On the other hand, the quantitative analysis
on this coexistence is still very limited.
Treatment-seeking behaviors might be determined not
only by the illness type but also by individual features suchas sex and age, availability of medical infrastructure andecological resources, modernity, and severity of illnesses [4,14, 15, 16, 17, 18, 19, 20]. Quantitative analyses taking
several different factors into account will be able to detectthe determining factors and, therefore, make progress in thedebate on how Western biomedicine and folk medicine coexist in a single society.

The purpose of this study was: (1) to explore the roleof different types of treatment based on daily records of responses to illnesses; and (2) to clarify which and how different factors affect treatment-seeking behaviors of the villagers in a single rural society of Solomon Islands, an area
experiencing the rapid Westernization over the last few decades. Special attention was paid to the effect of the typeand severity of illnesses, availability of a biomedical professional, patient’s sex and age, and socioeconomic status.
Multivariate analyses were applied for detection of determinant factors.

PARTICIPANTS AND METHODS
The permission for research was obtained from theSolomon Islands Government (Minister for Education andTraining and Director of Immigration Office). At the community level, the chief and elders also consented to thestudy. The study was performed according to international,
national, and institutional rules and was approved by the
Ethics Committee of Graduate School of Medicine, University of Tokyo. All of the data presented in this paper werecollected after gaining informed consent from the head andother members of participant households.

Division for International Relations, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8654, Japan８
４

Study site
Several traditional practices including herbal treatment
and other types of folk medicine are still in widespread use
in Solomon Islands [3, 5, 21, 22, 23]. Christian missions
initially introduced Western biomedicine and other services,and the government later took over the supply and supportof these services [21, 24]. However, their availability is still
limited in rural communities. In particular, there is a lackof Western biomedical professionals (e.g., medical doctors
and registered nurses) [25]. Registered nurses are not stationed throughout the year in village aidposts, which are themost accessible facilities for the residents of rural areas.
The fieldwork on which this paper is based was conducted from January to October 2001 in Olive village, aninner-Roviana-Lagoon village located in the southern partof New Georgia Island, Western Province. Olive village belongs to Saikile Customary Land, in which four villages andseveral small hamlets are under the Saikile Paramount Chieftoday [26, 27]. The inhabitants were 189 males and 158 females belonging to 49 households in February 2001. All
villagers were engaged in horticulture of tuberous crops andfishing.
The first Christian mission arrived in Roviana in 1902,
and most of the people had been converted by the mid
1920s. Western biomedicine came slowly to inner-Roviana
villages including Olive. Establishment of a provincial aidpost equipped with a variety of biomedical drugs opened
the way for most villagers to be treated with biomedicine by
the 1980s. The nurse, however, did not always stay in thevillage. For instance, a registered nurse left in November
2000 and another arrived in July 2001. At the time of thestudy, a small fee (approximately 1 US$) was required toconsult the nurse, although garden crops could be substituted as payment. There was a mission hospital with modern facilities in Munda (about 30 km west of Olive) and abetter-equipped national hospital in Gizo, the provincial
capital, about 80 km west of the village. Although medical
treatment at the two hospitals in the province was free or inexpensive, the villagers seldom visited them because of the
difficulty of transportation.
Recording responses to illnesses
For the interview survey concerning treatment of illnesses, 14 households (65 males and 51 females, accounting for 33.4% of the total population) were sampled. The
participants included a proportionate number of villagers
from each age group and sex. Each member of the participant household (or the parent for small children) was interviewed by the author every evening for 42 days about theoccurrence of illness experienced over the past 24-hour period and how it had been treated. It is noted that the dailyinterview was advantageous to record all cases however minor (e.g., small wounds) and to avoid dropouts. On occasions where the participant was absent, the interview was
conducted the following evening or later.
The names of illnesses reported by the participants
were initially recorded in the Roviana language. The author
later identified the symptom(s) related to each illness, referring to discussions with a group of healers (tie sinalana in
Roviana language) comprised of six males and three females. It should be noted that single symptoms (e.g., fever,cut/wound, and cough) or pain/ache in a specific part ofbody are called a ‘simple illness,’ while an illness with two
or more symptoms included in a name (e.g., malaria) is referred to as a ‘complex illness’ in this study (see Table 1).
In this paper, both treatment (sinalana in Roviana language) and no treatment for an illness are considered a ‘response.’ The number of person-days during the 42-day period was used as the basic unit of analysis. No nurse wasstationed in the village for the first 20 days of the study period, while a nurse was present at the aidpost for the last 22
days. Therefore, the whole study period was divided into
two periods.
Responses to an illness could be broadly divided into
three categories: (1) Western biomedicine, (2) folk medicine,and (3) no treatment. The Western biomedicine was divided
into two subcategories. The first referred to curing behaviors with modern drugs (meresena vaka in Roviana language), which had been purchased at stores in town or obtained at the hospital or aidpost in previous cases of illness
and kept in the patient’s house (hereafter called ‘modern
drug use’). The second was treatment following consultation with the nurse at the aidpost (vetu moho) and using
modern drugs (consulting a nurse); some treatment was carried out for every consultation. An important characteristicof consulting a nurse is that modern-drug prescriptions
based on Western biomedical standards and injections suchas penicillin are available, while biomedical check-ups formalaria and other illnesses, i.e. blood test, were not available at the aidpost. Treatments using folk medicine werealso divided into two subcategories. One was the use of
herbal medicine (herbal medicine use) and the other was
massage (mono) including acupressure. It should be notedthat the study village also has a tradition of treatment usingshells and other faunal resources, but these practices were
not observed during the study period.
Interviews on individual and household -level characteristics
Each participant or a parent was asked for his/her age
and sex. Male and female household heads (e.g., male headand his spouse and widowed female head and her first son)

８
５

Table 1. List of English illness names used in this study and the corresponding Roviana names (asterisk indicates illnesses recognized as fatal or severe)ａEnglish nameSimple illness
Chest ache
Cough
Cut/wound
Diarrhea
Eye (inflammation)
Fever
HeadacheMuscle ache
Rhinitis
Skin disorder
Sore throat
Stomach ache
Toothache
Vomiting
Complex illness
Illness with imported nameMalaria
Pneumonia
Illness with folk etiology
N. A.

Roviana names
Sigiti raqaraqa
Kohu
Bakora ｂ, poraka ＊Malohoro tia ｃ, huru ＊Mata kare
Diana (manini) ｄ, nunuale ＊, rarabuana ＊Sigiti batu
Sigiti tini ｅ, sigiti mudi, sigiti lima, sigiti avara
Puna
Moqo ｆ＊, tubu, tini hikare
Sigiti rua
Sigiti tia
Sigiti livo
Lua ｇ＊, iqolo, bekaha

Malaria hokara ｈ, malaria tia
Niumonia
Putuputu (kolo) , tuku ibibu, lagu hite, popome, mateana tia (tia hikare)ａClassifications of illness and severity were based on the group discussion of healers (tie sinalana).
ｂ
Bakora means cut/wound generally, while poraka means lacerated wounds recognized by the villagers as severer than the former.
ｃ
Malohoro tia is generally referred to as diarrhea, while huru means watery, probably bacterial, diarrhea.
ｄBoth diana (literally ‘cold’) and manini (‘hot’) refer to the same condition of fever, while nunuale refers to shaking chills andrarabuana to ‘paralysis’ recognized by villagers as the result of high fever.
ｅAches in whole body (tini), arm (lima), back (mudi), and shoulder (avara) were classified as muscle ache.
ｆTubu and tini hikare refer to pimples and chronic dermatitis, respectively, and moqo to inflamed or ulcerated ones.
ｇ
Lua refers to vomiting, iqolo to nausea and bekaha to nausea with abdominal complaints.
ｈMalaria hokara literally means ‘genuine malaria,’ while malaria tia means ‘abdominal malaria.’

were asked about their place of birth, age, education, experience of living in towns, and experience of waged job. To
ensure accuracy, both household heads confirmed the information. Dates of births were verified by referring to thewritten record, or using local history of well-known events
such as Independence Day and the date logging operationsin this area commenced.
Statistical analyses
Logistic regression analyses were performed so as todetermine which factors influenced the villagers’ responses
to illnesses. Factors included in the models were (A) typeof illness, (B) severity: (b1) the number of days counted
from the onset of illness and (b2) recognized severity (thename of illness which is recognized as severe = 1, others =0), (C) availability of nurse (during the period of nurse’s
presence = 1, during his absence = 0), (D) individual characteristics: (d1) age and (d2) sex, (E) household-level socioeconomic characteristics: (e1) type of house (Western-stylepermanent house = 1, others = 0), (e2) age, (e3) education
history (educated in secondary or higher school = 1, others= 0), (e4) place of birth (Saikile = 1, others = 0), (e5) experience of living in town (yes = 1, no = 0), and (e6) experience of waged labor (yes = 1, no = 0) of household head.
These procedures were performed using the SAS for
Windows version 9.1 (SAS Institute Inc., Cary, NC). A statistically significant association was assumed at p<0.05.

RESULTS
Occurrence of illness
Fifty-eight males (89.2%) and 39 females (76.5%) reported at least one episode of illness during the 42-day period. The total number of person-days in which responses
were observed (including “no treatment”) was 450 out of
4872 person-days (116 persons times 42 days). Out of the450, two illnesses were recorded for 131 person-days, andthree illnesses were recorded for 21 person-days. No caseinvolved four or more illnesses simultaneously. Most illness episodes ended rapidly; 66.1% of cases occurred inonly one day and 89.6% lasted for three days or less. Noneof the participants visited a hospital in town.

８
６

Table 1 shows the illness names in Roviana and thecorresponding English names. The latter are sorted by alphabetical order. In total, 33 types of illness were observed,
although it should be noted that none were diagnosed with abiomedical check-up. Out of these, 15 illnesses corresponded to single symptoms (i.e., three types of fever, rhinitis, cough or sneeze, three types of vomiting, two types ofdiarrhea, three types of skin disorders, and two types of cut
or wound) and seven to aches (sigiti in the Roviana language) in specific parts of the body (e.g., head, stomach,chest, throat, and tooth). Aches in the arm, shoulder, back,and whole body were classified as muscle ache. Roviana
names such as nunuale or rarabuana, huru, lua, moqo, andporaka refer to fatal or severe conditions of fever (diana),
diarrhea (maloholo tia), vomiting (iqolo/bekaha), skin disorders (tini hikare/tubu), and cuts (bakora), respectively.
Roviana names, such as malaria and niumonia, thewords for malaria and pneumonia borrowed from English
or Pidgin (the lingua franca of the Solomon Islands), wereused. Malaria consists of two different types: malaria
hokara (literally, “genuine malaria”) and malaria tia (“abdominal malaria”). The former is associated with fever andshaking with chills, whereas the latter does not show a fever
symptom but has complicated abdominal disorders diagnosed by palpation. Both illnesses were believed by the villagers to be caused by malaria nokinoki (“germs”). Niumonia showed fever and respiratory disorders (e.g., cough,chest pain, and sore throat).
It was difficult to determine the English equivalents offive illnesses, i.e., putuputu, tuku ibibu, lagu hite, popome,
and mateana tia, because of their complicated natures.
Putuputu (also called as kolo) showed combined symptomsof abnormal heartbeat, abnormal ventilation, sleep disorder,
fatigue, epigastric pain, and nausea. This illness was believed to be caused by problems with blood flow: several reDuring the absence of a nurse(20 days, 207 person-days)

spondents said that it was caused by hypertension. Tuku
ibibu means literally “the pit of the stomach is closed” andfeatures not only pain in the pit of the stomach but also abnormal respiration and anorexia. Popome was regarded as
an illness in which the lung was rotten or damaged by an ulcer. Both lagu hite and mateana tia (also called tia hikare)
were referred to as disorders of the intestinal organs, though
the former and latter were usually associated with the appendix and liver, respectively. These five illnesses werecategorized as illnesses with indigenous names and etiologies in further analyses of this study.
Patterns of treatment
Figure 1 shows participants’ responses to illnesses byabsence (207 person-days) and presence (243 person-days)of the nurse. Throughout the two periods, the most frequent
response was modern drug use (45.9% and 38.7% in the absence and presence of nurse, respectively), followed byherbal medicine use (29.0% and 27.8%). Consulting thenurse accounted for 17.8% of person-days during the presence of the nurse. Massage was used in 13.3% and 9.9% oftreatment during the absence and presence of nurse, respectively (accompanied by other types of treatment in about ahalf of cases). No treatment was observed in approximately
18% during both periods. The total frequency of Westernbiomedicine use (45.9%) and folk medicine use (40.1%)
was nearly equal during the period of the nurse’s absence,but the former (51.9%) increased and the latter (32.9%) decreased during the period of the nurse’s presence.
Table 2 shows all illnesses that occurred during thestudy period. Cases combining two or more illnesses simultaneously were counted for all and those undergoing
two types of treatment were also counted for both. Illnesses
were sorted by the order of the number of person-days ofmodern drug use. Three significant observations were madeDuring the presence of a nurse(22 days, 243 person-days)

No treatment
17.9%
HM + MS
2.4%

Modern druguse (MD)
42.0%

Massage(MS)
8.2%

Herbalmedicine use
(HM)
25.6%

No treatment
17.7%

Consulting
the nurse
(CN)
12.8%

HM + MS
1.6%
Massage(MS)
5.8%

Modern druguse (MD)
36.6%

Herbalmedicine use
(HM)
23.0%
MD + MS
2.9%

MD + HM
1.0%

MD + MS
2.1%

CN + MS
0.4%

Figure 1. Responses by type of treatment during the period of a nurse’s presence in the village (left)
and that of the nurse’s absence (right)

８
７

Table 2. Responses to illnesses occurring during the study periodａ，ｂWestern biomedicine
Consulting
ModernTotal
drug use a nurse
Simple illness
Fever
HeadacheMuscle ache
Rhinitis
CoughStomach ache
Vomiting
Chest ache
Toothache
Cut/wound
Sore throat
Diarrhea
Skin
Eye
Complex illness
Illness with imported nameMalaria tia
Malaria hokara
Niumonia
Illness with folk etiology
Lagu hite
Putuputu
Tuku ibibu
PopomeMateana tia
Total

Folk medicine
Herbalmedicine
use
Massage
Total

No
treatment

Total

67
48
27
24
23
20
12
11
5
5
4
4
3
1

8
9
6
2
4
1
0
2
0
3
2
1
4
1

75
57
33
26
27
21
12
13
5
8
6
5
7
2

1
0
7
0
6
11
5
2
0
20
0
5
57
0

9
5
7
2
2
5
4
3
0
2
5
0
14
0

10
5
14
2
8
16
9
5
0
22
5
5
71
0

8
8
16
4
3
4
2
0
1
19
3
1
9
1

93
70
63
32
38
41
23
18
6
49
14
11
87
3

15
5
11

0
2
0

15
7
11

1
0
0

1
0
2

2
0
2

1
0
1

18
7
14

4
3
2
1
0
295

0
0
3
0
0
48

4
3
5
1
0
343

1
9
0
2
4
131

1
7
0
0
1
70

2
16
0
2
5
201

0
0
0
0
0
81

6
19
5
3
5
625

ａ

Cases where two or more illnesses occurred simultaneously were counted for all and those induced more than one responses were alsocounted for both.
ｂIllnesses were sorted by the order of the number of person-days for modern drug use.

regarding the association between illness and response.
First, Western biomedicine, especially modern drug use,
was preferred in cases of headache, fever, cough, and rhnitis
whereas folk medicine was preferred for skin disorders andwounds. Abdominal pain and diarrhea were treated eitherwith Western biomedicine or folk medicine. Second, illnesses with names and etiologies introduced from abroad(malaria hokara, niumonia, and malaria tia) were treatedmainly with Western biomedicine. Malaria hokara wastreated only with modern drug use. Although not shown in
the table, all treatments using herbal medicine or massage
as responses to niumonia and malaria tia were accompanied simultaneously by the use of Western biomedicine.
Third, among the illnesses with indigenous names andetoiologies, putuputu, popome, and mateana tia weremainly treated by folk medicine and lagu hite and tuku
ibibu by Western biomedicine.

Factors determining an individual’s response
Western biomedicine was used in 48.7% and 50.0% of
treatments for males and females, respectively, and folk
medicine in 36.9% and 34.9%, respectively. ‘No treatment’
was observed in 17.8% and 18.4% of treatments for males
and females, respectively. Overall, there was no association
between responses and sex.
Figure 2 shows the responses broken down by age
groups (top) and by different days from the onset of illness(bottom). Western biomedicine was used for the treatment
of infants, children, and younger adults accounting for approximately 50% of person-days, while the most frequent
use was observed in the 30-60 year-old group (64.7%) andthe lowest among elders (8.3%). Folk medicine was usedmost frequently for the treatment of elders (87.5%), followed by that of infants (45.2%), but less in other age
groups (range: 23.4 to 29.3%). The proportion of no treatment was low in the age groups of infants and elders who
are generally vulnerable to disease.

８８Sixth, regarding illnesses, patients with fever or headache were treated more frequently with Western biomedicine (OR = 3.82 [1.81, 8.07] or 6.75 [2.75, 16.55], respectively) and less frequently with folk medicine. Cuts/
wounds or skin disorders were less likely to be treated with
Western biomedicine (OR = 0.23 [0.07, 0.78] and 0.13
[0.05, 0.52], respectively) but were not related with the useof folk medicine. Putuputu, the illness with a folk etiology,
was a positive factor for folk medicine treatment (OR =34.7 [3.13, 384.41]).

100
Folk medicine

80
Western biomedicine

(%)

60
40
20

No treatment0<5(N = 93)

5-18(N = 94)18-30(N = 82)30-60(N = 133)

60(N = 48)

Age groups (years)
70

DISCUSSION

60

(%)

50
40
30
20
10
0
1 day
(N = 244)

2 days(N = 81)

3 days(N = 37)

4-5 days(N = 49)

6-7 days(N = 25)

8-11 days(N = 14)

The number of days from the onset of illnesses

Figure 2. Frequency of response choices in different age
groups (top) and different days from the onset of
illness (bottom). The number of person-days isshown in parenthesis.

The frequency of Western biomedicine use reached apeak (59.5%) on the third day from the onset of illness,while that of folk medicine use peaked (46.9%) on the
fourth day. The frequency of both treatments decreased at
the sixth-to-seventh day and then increased again at theeighth-to-eleventh day, and folk medicine was used mostfrequently (50.0%) in this class of days. The proportion ofno treatment was highest on the first day (23.0%) and thenconstantly decreased, although a second peak (20.0%) appeared at the sixth-to-seventh day.
Logistic regression analysis was used to explore thedetermining factors for responses as shown in Table 3 (onlythose factors with significant effects were shown). First,
participants aged 60 years or more used Western biomedicine less frequently (OR (odds ratio) = 0.14 [95% CI (confidence interval) = 0.03, 0.76]) than other participants. Secondly, with regard to socioeconomic status, only the type ofhouse (living in Western-style permanent house) had a positive effect on biomedicine use. Socioeconomic status did
not have an effect on folk medicine. Third, the effect of thenurse’s presence was negative for folk medicine use (OR =0.39 [0.21, 0.72]). Fourth, Western biomedicine was used
more frequently on the third day of illness than other days.
Fifth, Western biomedicine was used more frequently (OR= 7.72 [2.65, 22.44]) and folk medicine less frequently (OR= 0.16 [0.06, 0.48]) for the treatment of severe illness.

The Role of folk medicine
In the community examined in the present study, folk
medicine was used in approximately 40% of all ill persondays. There have been few quantitative studies on the practice of traditional folk medicine in Melanesia and other indigenous societies. A previous study based on fortnightlyinterviews in Huli, a region of the Papua New Guinea Highlands where Christianity and European culture had arrived
in the 1950s, showed that folk medicine was used rarely, accounting for only 4% of all ill person-days in the 1970s [4].
Even taking into account the fact that the interview period
was different from this study, it is judged that folk medicine
has played a greater role in Roviana society than in Papua
New Guinea Highlands.
The results of logistic regression analysis revealed thefactors involved in the use of folk medicine. Firstly, the factthat none of the socioeconomic variables was related to theuse of folk medicine was important because it indicates thefamiliarity of folk medicine as an indigenous traditional
practice among villagers. It should be noted, however, thatthe preferred use among elders might reflect a strong cultural affinity continuing mainly in this age group while
younger generations are more likely to use Western biomedicine than folk medicine.
The analyses also revealed that folk medicine was preferred during the absence of the nurse and in the treatmentof less severe cases. These results suggest that folk medicine serves as an alternative to Western biomedicine andthat it is less important than Western biomedicine. This assumption is supported by the other result that both the nurse
and the villagers themselves turned to Western biomedicine
instead of folk medicine in cases of severe illness.
One of the most important findings, on the other hand,
was that folk medicine was used for the treatment of putuputu, an illness with an indigenous name and etiology. Several informants believed that Western biomedicine had noeffective way to deal with this illness whereas their own
medical system did. This belief is thought to have deter-８９Table 3. Factors for choosing Western biomedicine or folk medicine, determined by logistic
regression analysis (odds ratio and 95% confidence limit in parentheses)ａ

Individual characteristics
Age group (years)
60- (yes = 1; no = 0)
Household socioeconomic status
House (permanent = 1; leaf = 0)
Aidpost (open = 1; closed = 0)
Severity
Number of day
3rd day (yes = 1; no = 0)Class (severe = 1; else = 0)Illness
Simple illness
Fever (yes = 1; no = 0)
Headache (yes = 1; no = 0)
Cut/wound (yes = 1; no = 0)
Puna (yes = 1; no = 0)
Skin (yes = 1; no = 0)Complex illness
Putuputu (yes = 1; no = 0)
Wald statistics
P

Western biomedicine(450 person-days)

Folk medicine(450 person-days)

0.14(0.03, 0.76)

6.27(1.30, 30.13)

3.70(1.11, 12.33)
0.39(0.21, 0.72)

0.16(0.06, 0.48)

2.91 (1.02, 8.31)
7.72 (2.65, 22.44)

3.82 (1.81, 8.07)
6.75 (2.75, 16.55)
0.23 (0.07, 0.78)
0.13

0.23 (0.08, 0.61)
0.26 (0.08, 0.84)
0.16(0.03, 0.92)

34.70(3.13, 384.41)
102.29<0.0001(0.03, 0.52)

116.55<0.0001ａVariables with significant effects were shown; other variables included in the models were:(a) Individual characteristics:
Sex (male = 1), 5-18-year-old, 18-30-year-old, and 30-60-year-old age groups,(b) Household socioeconomic status:
Birthplace of household head (Saikile = 1; others = 0), age of household head, household head’s education
higher than primary school (yes = 1; no = 0), household head’s experience of living in town (yes = 1; no =0), household head’s experience of waged job (yes = 1; no = 0)(c) Characteristics of illness:
All illnesses shown in Tables 1 and 2 (yes = 1; no = 0).

mined their treatment-seeking behavior and suggests thatthe villagers continue to need folk medicine in addition to
newly introduced biomedicine. Overall, most of the folk
medical practices will likely be displaced by effective
Western-biomedical alternatives, but others, although limited in number, persist as culturally indispensable treatments for indigenous illnesses.
The Role of Western biomedicine
In general, Western biomedicine was used preferably
for the treatment of headache, fever, and introduced illnesses (i.e., malaria and pneumonia), although the effect of
the introduced illnesses disappeared when other factors
were adjusted. According to the respondents, medical personnel and schoolteachers discouraged the use of folk medicine for treatment of malaria and pneumonia because theseillnesses can be fatal and instead recommended the use ofWestern biomedicine as a powerful measure. In fact, thevillagers believed that almost all deaths in the village werecaused by these illnesses even though few of them had hada biomedical check. Related illnesses such as fever andheadache were therefore treated preferably with biomedicine. “Abdominal malaria (malaria tia)” was treated exclusively with biomedicine because of the villagers’ recognition that it is caused by a kind of “germ” which they described as being transmitted by flies. This indicated some
confusion regarding the cause of the illness. The Malaria
Control Programme has been the most intensively promoted
health program in Solomon Islands, but it seems to havecaused confusion regarding the cause of malaria. Indeed,
misunderstandings as to malarial etiologies have also beenreported in medical-sociological research in Malaita Province [29].
In the logistic models, housing type and severity of illness were also factors for the use of biomedicine. It is reasonable that Western biomedicine was preferably used in
the households with a permanent Western-style house sinceboth correlate with modernity. The fact that biomedicine
was used more frequently in severer cases and in the laterdays of illness suggested that the villagers in the study com-

９０munity recognize that biomedicine wields stronger curing
power than folk medicine.
Coexistence of folk medicine and Western biomedicine
Ethnographic studies have pointed out the existence of
medical pluralism, which is defined as the coexistence ofdifferent medical systems, in Melanesian societies [4, 9, 30,31]. The authors argue that traditional folk medicine andWestern biomedicine are complementary rather than competitive. The patterns of the community in the present study
where Western biomedicine is used for the treatment of illnesses originating from other areas and folk medicine for
putuputu, were similar to that of previous reports [4, 9, 12,13]. It is thus judged that Roviana society, like other societies [4, 30], is receptive to innovations that are readily available and effective, while maintaining useful indigenous
technologies.
This study, on the other hand, reveals the complicatednature of treatment choice as follows. First, the fact thattuku ibibu, an illness with an indigenous name and etiology,
was treated exclusively with Western biomedicine rather
than folk medicine (Table 2) indicated that medical systems
and illnesses should be recognized, not as dichotomous, but
as dynamic or plural. Second, the fact that the villagers’ behavior was strongly affected by the availability of a nurse
indicated that the role of both Western biomedical and folk
medical systems is dependent on availability of a biomedical professional even within a single society. In conclusion,
this quantitative analysis supported the existence of medical
pluralism in a rural society of the Solomon Islands, but suggested that this plurality is dynamic and subject to change
depending on the availability of a biomedical infrastructure.
Implications for International Health
The results of this study, which showed how villagers
accepted introduced biomedicine and often misunderstood
it while continuing to use their own folk medicine, are useful from the viewpoint of international health. For instance,
the improvement of the biomedical infrastructure by thecontinuous presence of a nurse, the appropriate supply of
drugs, and the provision of regular medical check-ups formalaria is an essential prerequisite for health promotion. In
the process, however, the appropriate dosage and use ofdrugs should be monitored because villagers often misunderstand Western biomedical notions and because the improper use of drug is potentially fatal [18, 31].
At the same time, from the viewpoint of encouraging
primary health care and conserving indigenous knowledge,
the effectiveness of folk medicine should also be positively
re-evaluated [2, 32]. Although traditional folk medicine has
undergone changes due to governmental health educationand policies, the Olive villagers still conserve knowledge of
their own medicine and practice it at a high frequency.
Since the biological effectiveness of some herbal plants
found in the Solomon Islands has already been recognized[33, 34], the appropriate use of folk medicine can help toreduce the cost of medical care. Moreover, when traditional
knowledge is disappearing quickly in the world, societies
still using folk medicine should be encouraged from theviewpoint of the conservation of indigenous environmental
knowledge [35].

ACKNOWLEDGEMENTS
I would like to thank the people of Olive village andother Saikile people, especially Rev. Nathan Kera, Mr. Cornelius Murray, and Mr. Edwin Huti, for their acceptanceand assistance. This study was conducted as part of a research project titled “Harmonization of rural development
and community welfare (leader: Prof. R. Ohtsuka),” financially supported by the Japan Society for the Promotion of
Science, the Ministry of Education, Culture, Sports, Science,
and Technology of Japan. Finally, I thank anonymous referees for their helpful comments on this paper.

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