Retroviruses in the Caribbean C. BARTHOLOMEW~ & F. CLEGHORN~ Transmission of HIV in many Caribbean countries has followed the pattern of initial predominance among homosexual and bisexual males, with the infection subsequently spreading into the heterosexual community. However, on Saint Lucia the epidemic began among heterosexual contacts of Saint Lucian laborers from Florida; in Bermuda 58% of AIDS cases have beenin intravenous drug abusers; and in the Bahamas 59% of the AIDS patients have been heterosexuals and 19% children infected via the perinatal route. Seroprevalence of the human T-lymphotropic virus, type 1 (HTLV-I), whose modes of transmission resemble those of Hm has beenfound to range from 2.3% in Trini- dad and Tobago to 5.4% in Jamaica. In a study of HIV and HTLV-1 infection patterns in homosexual males in ninidad and Tobago, the cohort was too small for confirmation that coinfection with these two viruses hastened progression to AIDS, but further investigation is warranted. dult T-cell leukemia was first de- lence of antibodies to HTLV-I in these pa- A scribed as a specific clinical entity by tients, who were born in Grenada, Guy- Takatsuki et al. (I) in 1977. In 1980 Poiesz ana, Jamaica, St. Vincent and the and his colleagues at the National Cancer Grenadines, and Trinidad and Tobago. Institute (2) reported detection and isola- Subsequently, Clark et al. (5) did an epi- tion of the first human T-lymphotropic vi- demiologic survey of the seroprevalence rus, HTLV-I, thereby culminating a long of antibodies to HTLV-I on the island of and hitherto fruitless search for a human St. Vincent, finding a seroprevalence of retrovirus. This work subsequently 3.3%. More recent studies in Suriname yielded the first clue to the relationship and Barbados have shown respective between HTLV-I and adult T-cell leuke- HTLV-I antibody seroprevalences of 3.0% mia (ATL)-a clue derived from seroposi- and 4.25% (6, 7). tive responses obtained with ATL case se- Similar surveys in Jamaica have shown rum samples provided to the researchers an overall seroprevalence of 5.4% in the by Ito of Kyoto University (3). general population (5) and have found as After clusters of p;TL cases were recog- many as 70% of all cases of non- nized on the islands of Shikoku and Hodgkin’s lymphoma in Jamaica to ex- Kyushu in southwestern Japan, Ca- hibit high-titer HTLV-I antibodies, which tovsky et al. (4) reported cases among six suggests that HTLV-I has contributed sig- black West Indians residing in the United nificantly to the occurrence of lym- Kingdom. The virus-disease relationship phoreticular neoplasia on that island (8). was documented by a high seropreva- In 1982 a random survey of the Trini- dad population was conducted to deter- ‘Department of Medicine, University of the West mine the seroprevalence of hepatitis B in- Indies, General Hospital, Port of Spain, Trinidad fection. This survey detected high and Tobago. Varibbean Epidemiology Center, Port of Spain, seroprevalences of hepatitis B antibodies Trinidad and Tobago. in both major ethnic groups-people of 76 PAHO Bulletin 23(2-2), 1989 African and Asian (Indian) origin (9).3 (16), intrapartum (17), or in breast milk When the stored sera from this survey (28). It has been found that HTLV-I, like were tested for HTLV-I antibodies, 37 HIV in the Western Hemisphere, is trans- (2.3%) of 1,578 samples tested by an mitted more readily from male to female enzyme-linked immunosorbent assay than from female to male (19). (ELISA) were found positive for HTLV-I. A prospective survey of lymphoreticu- However, 31 of 802 (3.9%) of the Trini- lar malignancies in Trinidad and Tobago dadians of African ancestry were sero- conducted from 1 October 1985 to 31 positive, together with five of 208 (2.4%) March 1988 found that non-Hodgkin’s persons of mixed African ancestry, while lymphoma accounted for 69 of 176 only one person out of 448 (0.2%) of In- (39.2%) of all subjects with lymphoreticu- dian descent was seropositive (10). This lar malignancies who were enrolled in disparity in ethnic seroprevalence stood the study. Of these 69 cases, 35 (50.7%) in marked contrast to the seroprevalence were positive for HTLV-I antibodies. Not of hepatitis B antibodies in the two major unexpectedly, all the patients with ATL in racial groups. Trinidad and Tobago to date have been The almost exclusive restriction of people of African ancestry. HTLV-I infection to the Afro-Trinidadian population supports the hypothesis of HIV-l-ASSOCIATED AIDS IN THE Gallo et al. (II) that HTLV-I came to the CARIBBEAN Caribbean via the African slave trade. (Although Trinidad is a cosmopolitan is- The first case report of AIDS in the land, the people of Indian origin have English-speaking Caribbean was from tended to settle in the rural agricultural Trinidad in early 1983 (20). Barbados, Ber- lands of central Trinidad, while the Afro- muda, Grenada, Jamaica, Saint Lucia, Trinidadians have tended to congregate and Suriname reported their first cases in in the urban areas.) The lone Trinidadian 1984; and Antigua, the Bahamas, Cay- of Indian origin who was seropositive for man Islands, St. Kitts/Nevis, and St, Vin- HTLV-I gave a history of frequent sexual cent and the Grenadines reported cases contact with many women of African de- in 1985. Anguilla’s first case was reported scent throughout the Caribbean islands. in 1987 (21). The modes of transmission of hepatitis Worldwide, three general patterns of B, HTLV-I, and the human immunodefi- HIV-l transmission have been found (22). ciency virus (HIV) are very similar- The first pattern, involving a spread of namely, by sexual contact (12); parenter- the virus that began in the mid-1970s to ally via blood transfusion (13) or early 198Os, was one in which transmis- intravenous drug abuse (14); and from sion occurred primarily through homo- mother to child (15), possibly in utero sexual contact, with intravenous drug abuse playing the next largest role. Re- gions where this pattern has prevailed in- 3Trinidad and Tobago, the two southernmost is- clude Western Europe, North America, lands in the Caribbean Basin, have a 1.2 million some parts of South America, Australia, population consisting mainly of people of Afri- and New Zealand. can (41%) and Asian (Indian) origin (41%), peo- ple of mixed racial descent (16%), Caucasians The second pattern, involving virus in- (l%), and Chinese (1%). The people of African troduced into the affected communities descent came to T&-&lad via tge Portuguese in the early to late 197Os, has affected pri- slave trade from 1680 onwards, while those of Indian origin came after the abolition of slavery marily heterosexuals. Where this pattern as indentured laborers beginning in 1845. prevails homosexual transmission has Barfhoh7zew b Cleghorn Refrovirusesin Caribbean 77 not been a major factor, but transmission predominantly sexual, with heterosexual via HIV-infected blood has come to pose transmission accounting for 59% of AIDS a major public health problem. Pattern II cases, homosexual/bisexual males ac- has been observed increasingly in parts counting for lo%, transfusions account- of Latin America, the Caribbean, and in ing for l%, and perinatal transmission ac- Central Africa. However, as will be dis- counting for up to 19%. In all, 63% of the cussed later, the pattern typically ob- heterosexual AIDS cases were found in served in the individual “English- cocaine abusers (not intravenous drug speaking” Caribbean islands does not abusers), who in turn were identified conform to this classification or indeed to with sexual promiscuity and prostitution any of the three principal patterns de- as a result of drug abuse. Because of this scribed. heterosexual predominance, the high The third pattern is one in which the percentage of pediatric AIDS cases is not virus has been introduced more recently, surprising. in the early to mid 1980s; both homosex- ual and heterosexual transmission are HTLV-I, HIV, AND AIDS IN only just being documented, and paren- TRINIDAD AND TOBAGO teral transmission is not a significant problem at present. Areas experiencing The first risk group to be affected with this pattern include Asia, the Pacific re- AIDS in Trinidad and Tobago was gion (apart from Australia and New homosexual/bisexual men, among whom Zealand), the Middle East, Eastern Eu- the numbers of cases initially doubled rope, and some rural parts of South about every 12 months. Specifically, America. there were eight cases in this risk group Regarding the Caribbean, the initial in 1983, 19 new cases in 1984, 33 in 1985, risk groups affected in Antigua, Barba- and 51 in 1986. In 1987 the number of dos, Grenada, Guyana, St. Kitts, and new cases in homosexual/bisexual men Trinidad and Tobago consisted of fell to 33, but the number of new AIDS homosexual/bisexual men. In these cases in heterosexuals kept rising-from places, especially Trinidad and Tobago, five in 1985 and 17 in 1986 to 29 in 1987- the infection has spread slowly into the so that these almost equalled the number heterosexual community via bisexual be- of new homosexual/bisexual cases. Of havior. In contrast, the AIDS epidemic on these 29 heterosexual cases, 15 occurred Saint Lucia was begun by heterosexual in males and 14 in females. This trend contacts of migrant Saint Lucian laborers continued through the first half of 1988, from Belle Glade, Florida (23). when 33 heterosexual cases and 29 Intravenous drug abuse is rarely prac- homosexual/bisexual cases were re- ticed on these islands. On Bermuda, ported. Fourteen of the 33 heterosexual however, 58.0% of the AIDS cases re- cases occurred in males and 19 in females ported up to May 1988 had occurred (Figure 1).