South Pacific Stusy Vol. 18, No. 2, 1998

Seroepidemiological Survey of Anti-Human T-cell
Leukemia Virus-Type I Antibodies in Western Samoa＊
Hideharu KUNIYOSHI 1), Motoo KITANO 2), Yasuto UCHIO 3),
Taulealeausumai Eti ENOSA 4), Leitua Faalii ALOAINA 5),
Vaasilifiti Faleniu ASAUA 6) and Shin-ichi TERASHI 7)†Abstract

A seroepidemiological survey of Anti-human T-cell Leukemia virus type I (HTLV-I) antibodies was conductedon Western Samoa human sera in 1993〜1994. The result showed no positive cases in all 1953 samples.
Key words: Seroepidemiology, Adult T-cell leukemia lymphoma (ATL), Anti-human T-cell leukemia virus
type I (HTLV-I) antibodies, Western Samoa

Introduction
Adult T-cell leukemia lymphoma (ATL) is caused by infection of a retrovirus, humanT cell leukemia virus type-I (HTLV-I). It is observed in high incidence among persons
born in virus endemic areas, such as south-western Japan, the Caribbean basin, CentralAfrica, southern part of India, north-eastern part of Australia and Papua New Guinea. Aneurological disease, HTLV-I associated myelopathy tropical spastic paraparesis (HAMTSP) is also caused by the same virus. It is said that many diseases are associated withHTLV-I infection. (HAB＝ HTLV-I associated bronchopneumonopathy, HAAP＝ HTLV-I
associated arthropathy, malignancies, etc.)
Many investigators have been making efforts to identify the ATL cases and HTLV-I
carriers, and their results showed that there are many HTLV-I positive cluster countries inthe world. Almost all the ATL patients and the carriers of HTLV-I are positive for antihuman T-cell leukemia virus-type I antibodies (anti-HTLV-I antibodies) in their sera. The
anti-HTLV-I antibody examination of the inhabitants in each country will help to detect andmonitor the incidence of leukemia and the transmission of the virus.

＊The Samoa Parliament passed the law to amend the Constitution changing the country’s name from Western
Samoa to Samoa in 1997. 1) Research fellow, First Department of Oral and Maxillofacial Surgery, Kagoshima
University Dental School, 8-35-1 Sakuragaoka, Kagoshima 890, Japan. 2) Professor, Department of Oral
Pathology, Kagoshima University Dental School, Kagoshima, Japan. 3)Professor, Division of Chemistry, Schoolof Allied Medical Sciences, Kagoshima University, Kagoshima, Japan. 4)Director General of Health Departmentof Samoa. 5) Consultant Anesthesiologist and Head of Anesthesia, Samoa National Hospital.
6)
Consultant Pathologist and Director of National Health Laboratory Service of Samoa. 7) Deceased, Professor,
Kagoshima University Research Center for the South Pacific, Kagoshima, Japan.

52South Pacific Study Vol. 18, No. 2, 1998

Material, Method and Results
The human sera were collected as available samples from Western Samoa National
Hospital Clinical Laboratories (Biochemical Laboratory and Microbiological Laboratory)
and Western Samoan Blood Transfusion Section, Apia, Western Samoa. The serologicaltest was done by the Microtiter Technique using a gelatin particle agglutination test
(Serodia HTLV-I kit, FUJIREBIO INC., Tokyo, JAPAN). The HTLV-I positive range wasdetermined over 16 units of serum samples concentration by this qualititative test. A totalof 1,953 samples were tested. The distribution of samples by age and sex are shown in
Table 1. As for 316 out of the 1,953 cases, the age or the age and sex was unclear. The
results of the present seroepidemiological study on Anti-HTLV-I antibody in WesternSamoa showed no positive cases in all samples (Table 1).
Table 1. Distribution of Sample Material by Age and Sex with Incidence of Positive Cases forAnti-HTLV-I Antibodies
AgeMaleFemale
Positive Cases
0-10

15

15

011-20105129021-30206

204

031-40113

140041-50111

108051-607984061-7078

58

071-49430

Age or Age&Sex
Unknown
Total

316
1,953

00Discussion
The adult T-cell leukemia lymphoma (ATL) is caused by an infection of a retrovirus,HTLV-I (HINUMA et al., 1981). Anti-HTLV-I antibodies in human sera are detectable inmost ATL patients and are in a relatively high percentage in healthy individuals born inATL-endemic areas (TAJIMA et al., 1984). Currently it is supposed that HTLV-I is transmitted by three main routes; 1) sexual transmission (TAJIMA et al., 1982), 2) verticaltransmission (HINO et al., 1985), and 3) blood transfusion (OKOCHI et al., 1983). It issuspected that there are 1.2 x 105 carriers in Japan, and ATL-endemic areas are the southwestern areas of Japan where healthy carriers were found at a rate between 6％ and 37％

KUNIYOSHI: Seroepidemiological Survey of Anti-Human T-cell Leukemia Virus-Type I Antibodiesin Western Samoa

53(TAJIMA et al., 1979; HINO et al., 1982). The West Indies Caribbean basin, Columbia,Brazil, southern India, Papua New Guinea, north-eastern Australia and central parts ofAfrica are also known as HTLV-I invaded areas (BLATINER et al., 1982; CATOVSKY et al.,
1982; O’BRIEN et al., 1983; TAJIMA et al., 1992). In the United States the incidence issporadic and most of the patients are black Americans.
A few seroepidemiological surveys have been made in Oceania. There was a reported
1.1％ anti-HTLV-I antibodies positive cases in the Solomon Islands (HINUMA et al., 1983).
Another survey reported 0％ in the Solomon Islands and Viti Levu (Fiji) of Melanesia (TERASHI et al., 1983). Yet another survey reported 0％ in the Fiji (NICHOLSON et al., 1992).
But in Papua New Guinea at Port Moresby, Lae and Wewak of Melanesia showed a rangeof 6.9-30.2％ positive cases (TERASHI et al., 1991; TERASHI et al., 1992). There was areported 0％ in Truck State (TERASHI et al., 1986), 1.9％ in Pohnpei (TERASHI et al.,1986), 6.8％ in Yap State of the Federated States of Micronesia (TERASHI et al., 1987a).
In the Republic of Palau of Micronesia it was reported at 10.8％ (TERASHI et al., 1987b).
Polynesia is not known as an area that has been invaded by HTLV-I. In some studies, noantibody was detected in sera from American Samoa, the Cook Islands, French Polynesia(NICHOLSON et al., 1992) and Hawaii (TAJIMA et al., 1992). A study revealed 0.07％
positive cases in French Polynesia (CHUNGUE et al., 1993). USHIJIMA et al. (1990) reported there were no positive cases in Tonga and Western Samoa. Our present exhaustive
study also showed no positive cases in Western Samoa. The incidences of anti-HTLV-I
antibodies in Micronesia and Melanesia and its absence in Polynesia including WesternSamoa suggests certain patterns of socio-cultural interaction and early human migrations in
the Pacific Basin. However, further research, is necessary to ascertain these relationships.

Acknowledgements
We thank Mr. Tipasa ME (Health Planning Unit, Western Samoa health Department),
Ms. Letuu SLAVEN (Principal, Medical Laboratory Technologist, Samoa NationalHospital), Mr. Suesue TALALELEI (Pathological Technologist, Samoa National Hospital),
Mr. Palauni MAURIRATA (Pathological Technologist, Samoa National Hospital), Ms. T.S.
MAUAULA (Research Laboratory of the Red Cross Blood Transfusion Section, Samoa) andMr. Faapulou AUVAA (Supervisor Biochemistry Unit, Samoa National Hospital) for their
help in this project.
This research work was supported by a Grant-in-Aid for Cancer Research (No.0604212)
from the Ministry of Education, Sciences and Culture, Japan.

54South Pacific Study Vol. 18, No. 2, 1998

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