Kagoshima University Research Center for the Pacific Islands, Occasional Papers No.34, 129-132, 2001
Part 1, Section 3, Report 7. The Progress Report of the 1999 Survey of the Research Project“Social Homeostasis of Small Islands in an Island-zone”

129

MEDICAL SURVEYS ON YAP PROPER: INTESTINAL HELMINTHIC
INFECTIONS, DISTRIBUTION OF MOSQUITOES AND HEALTHCONDITION OF INHABITANTS
Shinichi NODA, John GILMATAM, Kiyotaka YOSHIIE and Kazumasa OGINO

Abstract
Of 111 persons examined , 12 (10.8%) were infected with one or two intestinal parasites. Eggsof helminths found were Ascaris lumblicoides, hookworm and Trichuris trichura. The prevalence ofT. trichura was relatively high in Rull. Larval mosquitoes were collected at 60 habitats which are composed of coconut shells, cans of drinks, tree holes, old tires, artificial containers, drums for drinking
water, canoes, small water pool, and dam. Ten mosquito species were collected at various natural andartificial habitats, and Aedes hensilli was the most abundant mosquito species. The habits of smoking
and/or bettlenut chewing with lime and tobacco seemed to relate with hypertension and alkaline urine.
Key words: Intestinal parasite, Mosquito, Health condition

We carried out surveys of intestinal helminthic infections, distribution of mosquitoes andhealth condition of inhabitants on Yap Proper.

Survey of Intestinal Helminthic Infections
Parasitism is usually considered as a common condition in rural populations in developing
countries. Although the mortality rate by intestinal helminthic infections is rather low, these infections are recognized as a serious public health problem because of the high prevalence. Here
we describe the prevalence of intestinal helminthic infection among inhabitants in Yap Proper.
The survey was conducted by stool examination in October 1999. Fececes of 111 inhabitants aged 1 to 72 (56 males and 55 females) from six municipalities in Yap proper were examined for intestinal helminthic infections by thin smear method after fixation in 10% formalin.
Table 1 presents the result of the stool examination. Of 111 persons examined, 12 (10.8%)
were infected with one or two intestinal parasites. Eggs of helminths found were Ascaris
lumblicoides, hookworm and Trichuris trichura. Eleven persons had one parasite infection andTable 1. Prevalence of intestinal parasites in Yap Proper
MunicipalityNo.
examined

Dalipebinaw
Gagil
MaapRullTomil
Weeloey
Total

1262442522111No. positive
Ascaris lumblicoides
0002002Hookworm
0020002

Trichuris trichura0009009Shinichi NODA et al.

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one person had two parasite infections, A. lumblicoides and T. trichura. The pattern of infection
in six municipalities was not similar. Infections of A. lumblicoides and T. trichura were foundonly in Rull, and hookworm infection in Maap. The prevalence of T. trichura was relatively high(21.4%) in Rull.
The number of patients visited hospital because of intestinal parasites decreased from 688
to 277 during the period of 1988 to 1992 (Yap State, 1995). As intestinal parasites infections
occur closely relating to the environmental sanitary condition, the decrease of patients may indicate the improvement of the sanitary conditions in Yap Proper. However, transmissions of intestinal helminthic infections are still occurring in some municipalities. The sanitation improvement
and health education should be continued for transmission control of parasites.

Distribution of Mosquitoes
The most important group of biting insect is the mosquitoes. Their biting is a considerable
nuisance in many parts of the world. More importantly, mosquitoes are carriers of a number of
diseases, mostly in the tropics, causing illness and death on a large scale. Dengue fever is causedby several closely related viruses, called dengue type 1, 2, 3 and 4. The disease is transmitted
from person to person mainly by Aedes aegypti, but Aedes albopictus can also act as a vector.
Two forms of the disease occur; dengue fever and dengue haemorrhagic fever. The disease isprevalent in the tropics and subtropics particularly Southeast Asia. World Health Organization
estimates that 2000 million people are at risk. Each year there are millions of infection and thousand of deaths. Recently, A dengue fever/dengue haemorrhagic fever outbreak in Yap Statecaused by dengue-4 virus was confirmed serologically and by virus isolation from serum samples. And, entomologic investigations implicated the native mosquito species, Aedes hensilli asa previously unrecognized epidemic vector of dengue viruses (S AVAGE et al., 1998). We report
here the fauna and breeding sites of mosquitoes in Yap Proper.
Surveys of larval mosquitoes were carried out on February, October and November 1999 innine municipalities of Yap Proper except Rumung. Larval mosquitoes were collected at 60 habitats which are composed of coconut shells, cans of drinks, tree holes, old tires, artificial containTable 2. Number of mosquitoes and their habitat types collected in Yap ProperSpecies
Culex (Culex) annulirostris

No. collected (%)
3 (0.4)Culex (Culex) quinquefasciatus
Culex (Culex) sitiens
Culex (Culex) tritaeniorhynchus
Culex (Lutzia) fuscanus
Aedes (Stegomyia) hensilli

35 (4.8)
5 (0.7)1 (0.1)3 (0.4)506 (70.0)

Aedes (Stegomyia) maehleri

97 (13.4)

Aedes (Skusea) lamelliferus

61 (8.4)

Aedes sp.
Aedeomyia catasticta

5 (0.7)7 (1.0)

Habitat types
Coconut shell
Small water pool
Can, Tire
Small water pool
Tire
Tire
Coconut shell, Can,Tire
Drum, Tree hole, Canoe
Coconut shell, Tier
Tree hole, Canoe
Coconut shell, Drum, Tire
Tree hole, Canoe
Small water pool, Drum
Dam, Small water poolMedical Surveys on Yap Proper: Intestinal Helminthic Infections, Distribution of Mosquitoes and Health Condition of Inhabitants 131ers, drums for drinking water, canoes, small water pools, and a dam (source of water supply).
Table 2 presents the result of the mosquito collection. Ten mosquito species were collected
at various natural and artificial habitats. Aedes hensilli was the most abundant mosquito species.
Larvae of Aedes hensilli were mainly collected at coconut shells and cans of drinks, and also attire, drum, canoe tree hole. Aedes larvae are container-breeders which thrive in both clean andorganically rich water in both natural and artificial containers. Destruction or elimination of unwanted natural and artificial containers in and around human living premises definitely contribute to an overall reduction of Aedes population. In Yap Proper, coconut shells and cans should
be removed to prevent accumulation of water and larval breeding near houses.

Health Condition of Inhabitants
Yap proper is not isolated from foreign countries now, and life style of inhabitants is influenced from outer civilization. As imports of many kinds of foods changed a habit of eating, diabetes and hypertension seem to increase in number. As we have an interest in the relationship ofhealth condition of Yapese with habits of smoking, chewing bettlenuts and eating, we performed
measurement of blood pressure, urine analysis and questionnaires.
We checked the health condition of 69 inhabitants with a medical team delivered from theYap Hospital in three villages of Yap Proper. These inhabitants included 47 males from 9 to 75
years old, and 22 females from 16 to 63 years old. They were 61 of Yap proper, two of Faraulep,
one of Ifalik, two of Lamotreck and three of Satawar. We measured blood pressure, and analyzed
urine. Levels of blood sugar of volunteers were also measured. Sixty-one inhabitants filled out
our questionnaire forms for check habits of smoking, chewing bettelnut.
Hypertension is a state of systolic pressure over 160 mmHg and/or diastolic pressure over
90 mmHg. 13.6% of female and 27.7% of male were hypertensive in systolic, and 18.2% of female and 27.7% of male were hypertensive in diastolic pressure. This criteria for hypertension
is adopted when objective person was calm. In the field, people were in sitting position and after
walking to the place the medical team gathered when we checked their blood pressure. This condition seemed to influence the level of blood pressure. As, considering this point, we adopted ourcriteria for hypertension as over 200 mmHg in systolic and/or 100 mmHg in diastolic pressure,
three females (13.6%) and six males (12.8%) were hypertensive. This hypertensive group include one female and five males with habits of smoking relating to hypertension.
Eleven females and 13 males received urine test. None of females showed protein in urine.
15.4% of males was positive, but they were negative of occult bleeding in urine. One of them
revealed high value over than 30 mg/ml of protein. Occult bleeding in urine was positive in fivefemales (45.5%). As three of them were menopausal, renal and/or uterine disorders were strongly
Table 3. Habitats of smoking and chewing of bettlenuts
Habitats
Non-smoker
Smoker less than one package a day
Smoker over one package a day
Chewing of bettlenuts
Chewing of bettlenuts with tobacco
Smoking and chewing of bettlenuts with tobacco

Male
27/41
10/41
4*/41
33/41
22/33
1/33

* Three of them were diabetic, occult blood-positive or urine protein-positive.

Female
18/21
2/21
1/21
16/21
13/16
0/16

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Shinichi NODA et al.

suspected. In males, three over 40 years old showed occult bleeding in urine. As five of occult
blood-positive seven persons over 40 years old were hypertensive, renal disfunction was suspected.
One male showing positive urine glucose was diabetic because of his hyperglycemia of 309
mg/dl.
Interestingly, several urine revealed strong alkaline pH over 7. All of these person had ahabit of bettlenut chewing with tobacco and lime (Table 3). As this might influence effects ofdrugs absorbed from alkaline urine, the dose, timing and interval of medication should be considered in Yapese.

References
SAVAGE, H.M., FRITZ, C.L., RUTSTEIN, D., Y OLWA, A., V ORNDAM, V. & GULBLER, D.J. 1998.
Epidemic of Dengue-4 Virus in Yap State, Federated States of Micronesia, and Implicationof Aedes hensilli as an Epidemic Vector. Am. J. Trop. Med. Hyg., 59: 519-524.
Yap State 1995. Statistical Yearbook. Officeof Planning and Budget, Yap State. 136 pp.