Prevalence of retrovirus, hepatitis B and D infection in the Matsés ethnic group in Loreto, Peru. / Prevalencia de infección por los virus de la hepatitis B, D y por retrovirus en la etnia Matsés (Loreto, Perú).

Observational, cross-sectional, populational study to determine the prevalence of infection by hepatitis B virus (HBV), hepatitis D virus (HDV), human immunodeficiency virus (HIV) and human T-lymphotropic virus type 1 and 2 (HTLV-1/2) in the Matsés ethnic group, after immunization against HBV. ELISA and qPCR tests were used in 963 residents. The prevalence of HBsAg, Anti-HBc and Anti-HBs was 3.32%, 36.03% and 58.67% respectively. In 3.1% of the population the viral load was greater than 2000 IU/mL. In children under 10 years, the prevalence of HBsAg and anti-HBc was 0.0% and 2.6%, respectively, while protective antibodies were found in 94.4%. The prevalence of HIV and HTLV-1/2 infection was 1.5% and 0.6%, respectively. It is therefore concluded that there are low rates of HBV and HDV infection in the Matsés child population. Likewise, the presence of HIV and HTLV-1/2 infection is confirmed.

Para determinar la prevalencia de infección por los virus de la hepatitis B y D (VHB y VHD, respectivamente), VIH y HTLV-1/2 en la etnia matsés, después de la inmunización contra el VHB se realizó un estudio transversal y poblacional, utilizando pruebas de ELISA y qPCR en 963 pobladores. Las prevalencias de HBsAg, anti-HBc y anti-HBs fueron 3,3%, 36,0% y 58,7%, respectivamente. En el 3,1% de la población la carga viral fue mayor a 2000 UI/mL. En menores de 10 años, la prevalencia de HBsAg y anti-HBc fue 0,0% y 2,6%, respectivamente, mientras que en el 94,4% se encontraron anticuerpos protectores. La prevalencia de infección por el VIH y el HTLV-1/2 fue 1,5% y 0,6%, respectivamente. Se concluye que existen tasas bajas de infección por el VHB y el VHD en la población infantil de la etnia matsés. Asimismo, se confirma la presencia de infección por el VIH y el HTLV-1/2.

HTLV screening of blood donors using chemiluminescence immunoassay in three major provincial blood centers of China.

BACKGROUND: Human T-cell lymphotropic virus (HTLV) remains a major safety concern for blood supplies. Despite many HTLV positive cases being reported in southeastern China, the detection of HTLV has not been prioritized in routine blood screening. Additionally, data on the prevalence of HTLV infection among blood donors is also limited. The objective of this study was to investigate the prevalence of HTLV among blood donors in three Chinese provinces through their representative blood centers, to evaluate the feasibility of chemiluminescence immunoassay (CLIA) for blood screening. METHODS: From November 2018 to March 2019, blood plasma samples were collected from Hebei, Changsha, and Shenzhen blood centers and were screened for the HTLV-1/2 antibody using a CLIA and enzyme-linked immunosorbent assay (ELISA). This was followed by confirmatory tests using INNO-LIA HTLV I/II. RESULTS: A total of 59,929 blood donations were collected and screened for HTLV-1/2. The reactive rate of CLIA and ELISA among donations in the Shenzhen blood center (0.0943%, 27/28,621) was higher than Hebei (0.0248%, 4/16,144), and Changsha (0.0198%, 3/15,164) (p < 0.05). After confirmation, 3 samples were confirmed as indeterminate for HTLV antibodies, and only one sample from the Shenzhen blood center was confirmed as HTLV-1. The overall prevalence of HTLV-1/2 was 1.67 per 100,000 (1/59,929). The HTLV-infected blood came from a 32-year-old first-time female donor with a high school degree, who belonged to the SHE ethnic minority and was born in the Fujian province. CONCLUSIONS: In summary, the overall prevalence of HTLV-1/2 among blood donors in the three blood centers in China remains relatively low. However, blood donations with positive or indeterminate results for HTLV antibodies reminded us of the importance of HTLV screening among blood donors in China.

Prevalencia de infección por los virus de la hepatitis B, D y por retrovirus en la etnia Matsés (Loreto, Perú) / Prevalence of retrovirus, hepatitis B and D infection in the Matsés ethnic group in Loreto, Peru

RESUMEN Para determinar la prevalencia de infección por los virus de la hepatitis B y D (VHB y VHD, respectivamente), VIH y HTLV-1/2 en la etnia matsés, después de la inmunización contra el VHB se realizó un estudio transversal y poblacional, utilizando pruebas de ELISA y qPCR en 963 pobladores. Las prevalencias de HBsAg, anti-HBc y anti-HBs fueron 3,3%, 36,0% y 58,7%, respectivamente. En el 3,1% de la población la carga viral fue mayor a 2000 UI/mL. En menores de 10 años, la prevalencia de HBsAg y anti-HBc fue 0,0% y 2,6%, respectivamente, mientras que en el 94,4% se encontraron anticuerpos protectores. La prevalencia de infección por el VIH y el HTLV-1/2 fue 1,5% y 0,6%, respectivamente. Se concluye que existen tasas bajas de infección por el VHB y el VHD en la población infantil de la etnia matsés. Asimismo, se confirma la presencia de infección por el VIH y el HTLV-1/2.

ABSTRACT Observational, cross-sectional, populational study to determine the prevalence of infection by hepatitis B virus (HBV), hepatitis D virus (HDV), human immunodeficiency virus (HIV) and human T-lymphotropic virus type 1 and 2 (HTLV-1/2) in the Matsés ethnic group, after immunization against HBV. ELISA and qPCR tests were used in 963 residents. The prevalence of HBsAg, Anti-HBc and Anti-HBs was 3.32%, 36.03% and 58.67% respectively. In 3.1% of the population the viral load was greater than 2000 IU/mL. In children under 10 years, the prevalence of HBsAg and anti-HBc was 0.0% and 2.6%, respectively, while protective antibodies were found in 94.4%. The prevalence of HIV and HTLV-1/2 infection was 1.5% and 0.6%, respectively. It is therefore concluded that there are low rates of HBV and HDV infection in the Matsés child population. Likewise, the presence of HIV and HTLV-1/2 infection is confirmed.

Predominance of human lymphotropic T cell virus type 2 subtype B in urban populations of Argentina.

Human T-lymphotropic virus subtype b (HTLV-2b) infection has been described among aborigines from Northern Argentina, while HTLV-2a has been described in an injecting drug user (IDU) from a Central region, similar to the situation in Spain, the United States, and Brazil. In this study, 22 of the 26 strains analyzed from blood donors and HIV-1(+) individuals were HTLV-2b (84.6%) clustering with Amerindian references, while 4 HIV-1(+) (15.4%) were HTLV-2a. HTLV-2a sequences were closely related to Brazilian references in contrast to the previous Argentinean IDU strain that clustered with Africans and Amerindians from North America. In summary, these findings show that HTLV-2b is the major strain circulating in an urban population of Argentina. HTLV-2a/b could have been introduced from endemic South American countries such as Brazil and because of contact with other populations such as IDUs from Europe despite its introduction due to the increasing internal migration of aborigines to large urban centers. Considering this results and recent data about the dissemination of HTLV-1 in residents of Buenos Aires city, new studies among non-at-risk groups for HTLV-1/2 infection should be performed.

Stable human T-cell lymphotropic virus type 1 (HTLV-1) subtype a/subgroup a endemicity in Amerindians from Northwest Argentina: a health problem to be resolved.

Jujuy province, in Northwest Argentina, is known to be endemic for HTLV-1 infection. Moreover, foci of HTLV-1 associated pathologies have also been described in this region. To gain an insight into the current situation of HTLV-1/2 in this endemic area, a seroprevalence and phylogenetic study was performed among a Kolla community from Abra Pampa city and surroundings. Out of 112 individuals, 11 (9.8%) were confirmed as HTLV-1 positive and no HTLV-2 infection was detected. The phylogenetic analysis of the LTR region showed that all the HTLV-1 sequences belonged to the Cosmopolitan subtype a/transcontinental subgroup A, and were closely related to reference sequences from Peru, Argentina, and the South of Brazil (P = 0.82). Considering the cultural and historical features of this community and in spite of the mandatory detection of anti-HTLV-1/2 antibodies in blood banks since 2005, it would be important to implement new public health measures focused on decreasing HTLV-1 transmission in this endemic area.

Identification of human T-cell lymphotropic virus infection in a semi-isolated Afro-Brazilian quilombo located in the Marajó Island (Pará, Brazil).

Antibodies to human T-cell lymphotropic virus-1 and 2 (HTLV-1 and 2) were tested in 259 inhabitants (98 males and 161 females) of four villages of the Marajó Island (Pará, Brazil) using enzyme immunoassays (ELISA and Western blot). Types and subtypes of HTLV were determined by nested polymerase chain reaction (PCR) targeting the pX, env and 5 LTR regions. HTLV-1 infection was detected in Santana do Arari (2.06%) and Ponta de Pedras (1%). HTLV-2 was detected only in Santana do Arari (1.06%). Sequencing of the 5 LTR region of HTLV-1 and the phylogenetic analysis identified the virus as a member of the Cosmopolitan Group, subgroup Transcontinental. Santana do Arari is an Afro-Brazilian community and the current results represent the first report of HTLV-1 infection in a mocambo located in the Brazilian Amazon region.

Identification of human T-cell lymphotropic virus infection in a semi-isolated Afro-Brazilian quilombo located in the Marajó Island (Pará, Brazil)

Antibodies to human T-cell lymphotropic virus-1 and 2 (HTLV-1 and 2) were tested in 259 inhabitants (98 males and 161 females) of four villages of the Marajó Island (Pará, Brazil) using enzyme immunoassays (ELISA and Western blot). Types and subtypes of HTLV were determined by nested polymerase chain reaction (PCR) targeting the pX, env and 5 LTR regions. HTLV-1 infection was detected in Santana do Arari (2.06 percent) and Ponta de Pedras (1 percent). HTLV-2 was detected only in Santana do Arari (1.06 percent). Sequencing of the 5 LTR region of HTLV-1 and the phylogenetic analysis identified the virus as a member of the Cosmopolitan Group, subgroup Transcontinental. Santana do Arari is an Afro-Brazilian community and the current results represent the first report of HTLV-1 infection in a mocambo located in the Brazilian Amazon region.

Human T-lymphotropic virus type I and II infections in First Nations alcohol and drug treatment centres in British Columbia, Canada, 1992-2000.

Since 1992, prevalence data on HTLV-I and II have been collected as part of an ongoing viral seroprevalence study in clients of six First Nations alcohol and drug treatment centres in British Columbia, Canada. Prior studies indicate that the lifetime risk of clinical disease (neurologic or hematologic) resulting from HTLV-I infection is low (less than 5%) and HTLV-II to date has not been clearly associated with clinical disease. In 1993, the first cases of HTLV-I-associated myelopathy or tropical spastic paraparesis (HAM/TSP) were reported in four Aboriginal residents of British Columbia; these were the first reports of HTLV-I linked disease among Aboriginal persons in Canada. All clients of the treatment centres involved in this study were offered confidential, voluntary testing following pre-test counseling, and the results are given to participants before the residential session is complete. 1953 men and women were tested; 11 were positive for HTLV-1 (0.56%) and 33 were positive for HTLV-2 (1.8%).

First seroepidemiological study and phylogenetic characterization of human T-cell lymphotropic virus type I and II infection among Amerindians in French Guiana.

We investigated the serological, epidemiological and molecular aspects of human T-cell lymphotropic virus type I and II (HTLV-I/II) infection in the Amerindian populations of French Guiana by testing 847 sera. No HTLV-II antibodies were detected, but five individuals (0.59%) were seropositive for HTLV-I. Analysis of the nucleotide sequences of 522 bp of the env gene and the compete LTR showed that all of the strains from French Guiana belonged to the cosmopolitan subtype A. The similarities were greater between Amerindian and Creole strains than between Amerindian and Noir-Marron strains or than between Creole and Noir-Marron strains. Phylogenetic analysis showed two clusters: one of strains from Amerindians and Creoles, which belong to the transcontinental subgroup, and the other of strains from Noirs-Marrons, belonging to the West African subgroup. Our results suggest that the Amerindian HTLV-I strains are of African origin.

Characteristic distribution of HTLV type I and HTLV type II carriers among native ethnic groups in South America.

To confirm the geographic and ethnic segregation of HTLV-I and HTLV-II carriers in native populations in South America, we have conducted a seroepidemiological study of native populations in South America, including HTLV-I carriers distributed among seven ethnic groups in the Andes highlands of Colombia, Peru, Bolivia, Argentina, and Chile, and two ethnic groups on Chiloe Island and Easter Island; and HTLV-II carriers distributed among seven ethnic groups of the lowlands along the Atlantic coast of Colombia, Orinoco, Amazon, and Patagonia, and one ethnic group on Chiloe Island. The incidence rate of HTLV-I and HTLV-II carriers varied among the ethnic groups, ranging from 0.8 to 6.8% for HTLV-I seropositivity and from 1.4 to 57.9% for HTLV-II seropositivity. A new HTLV-I focus was found among the Peruvian Aymara (1.6%), the Bolivian Aymara (5.3%) and Quechua (4.5%), the Argentine Puna (2.3%), and the Chilean Atacama (4.1%), while on HTLV-II focus was found among the Brazilian Kayapo (57.9%), the Paraguayan Chaco (16.4%), and the Chilean Alacalf (34.8%) and Yahgan (9.1%). The distribution of HTLV-I/II foci showed a geographic clustering of HTLV-I foci in the Andes highlands and of HTLV-II foci in the lowlands of South America. It was thus suggested that South American natives might be divided into two major ethnic groups by HTLV-I and HTLV-II carrier state.

HTLV-II risk factors in Native Americans in Florida.

Earlier virologic studies established that human T-cell lymphotropic virus type II (HTLV-II) is the predominant retrovirus type found among Seminole Indians in southern Florida. We studied 46 members of the Seminole tribe living on 3 reservations to determine the risk factors for HTLV-II and to investigate disease association with the virus. The donors' plasma samples were evaluated with the enzyme-linked immunosorbent and Western blot assays. DNA extracted from their peripheral blood mononuclear cells were analyzed by type-specific polymerase chain reaction amplification and detection of the HTLV pol gene using the primer pair SK110/SK111, and the probes SK112 or SK188. One of 46 (2%) subjects was identified as HTLV-I positive and 11 (24%) were identified as HTLV-II positive. Restriction fragment length polymorphism and sequence analyses indicated that all of the HTLV-II strains were subtype b. Mitochondrial DNA analyses indicated that all of the HTLV-II-positive subjects had an Amerindian haplotype. HTLV-II was more prevalent in Indians who were >45 years of age or female, had multiple sex partners or had received a blood transfusion. However, only the latter risk factor was statistically significant. Three of the HTLV-II-positive Indians demonstrated signs and symptoms of an ataxic neuropathy. The data support that HTLV-IIb is endemic among the Seminoles and that they will be a key population for further virologic studies.

Endemic infection with HTLV-IIB in Venezuelan Indians: molecular characterization.

The peripheral blood of 41 Yaruro and Guahibo Indians from Venezuela was examined for HTLV antibodies and DNA. Twenty-five samples (61%) were found to be infected with HTLV-IIB. The sensitivities of the serologic and DNA polymerase chain reaction (PCR) analyses were 80% and 96%, respectively. Epidemiologic studies supported both sexual and perinatal transmission of the virus. Sequence analyses of the HTLV-IIB strains from these Indians indicate that they are unique relative to HTLV-II detected in other groups of humans. HTLV-IIB-G2 isolated from a Guahibo Indian is the most divergent HTLV-IIB strain relative to the prototype HTLV-II NRA.

[Infection with T-lymphotropic virus in Dutch blood donors, 1993-1996]. / Infectie met humaan T-lymfotroop virus bij Nederlandse bloeddonoren, 1993-1996.

Infection with human T-lymphotrophic virus (HTLV) type 1 causes a neurological disorder or leukaemia in a minority of infected persons. Since January 1993 the Dutch blood banks screen each donation for presence of HTLV-1 infection. Approximately 4,000,000 donations from 700,000 donors have been tested. The numbers of confirmed HTLV-1 positive donors were: 1993: 15; 1994: 6; 1995: 8; 1996: 3. In 1995 one case of HTLV-2 infection was detected as well. In 26/32 (81%) of the HTLV-1 positive cases either the donor or his/her partner originated from HTLV-1 endemic areas. The introduction of HTLV screening prevents the silent spread of HTLV via blood transfusion.

Molecular phylogeny of human T-cell leukemia virus type I and II of Amerindians in Colombia and Chile.

Six human T-cell leukemia virus type I (HTLV-I) and eight human T-cell leukemia virus type II (HTLV-II) cases newly isolated from the South American countries of Colombia and Chile were analyzed together with the two Amerindian HTLV-I isolates previously reported. All of the HTLV-I isolates belonged to the transcontinental subgroup of the "cosmopolitan" group, and Colombian isolates, including those from native Amerindians and Negroes, formed a single tight cluster within this subgroup. The transcontinental subgroup consisted of isolates from various regions such as the Caribbean basin, India, Iran, South Africa, Sakhalin, and Japan, and included isolates from the "Ainu" and "Okinawa" people, regarded as relatively pure Japanese descended from the prehistoric "Jomon" period which began more than 10,000 years ago. This implied a dissemination of the subgroup associated with the movement of human beings in ancient times. On the other hand, all of the HTLV-II isolates from native Amerindians in Colombia and Chile belonged to the HTLV-IIb subtype which has previously been reported to be mainly endemic in certain populations of native Amerindians. The southernmost isolate from Chile, showing wide distribution of the IIb subtype in native South Amerindians and largest heterogeneity of the subtype in Colombian isolates, supported the idea that the HTLV-IIb subtype has been endemic for a long time in native Indians of South America.

Comparative performances of enzyme-linked immunosorbent, western blot, and polymerase chain reaction assays for human T-lymphotropic virus type II infection that is endemic among Indians of the Gran Chaco region of South America.

BACKGROUND: Human T-cell lymphoma/leukemia viruses types I and II (HTLV-I and HTLV-II) are related exogenous human retroviruses. The former is definitely pathogenic while disease association with the latter is unclear. There are two subtypes of HTLV-II, A and B. Currently, enzyme-linked immunosorbent assays (ELISAs) based on HTLV-I antigens are used to screen for the presence of HTLV-I and -II antibodies. Confirmation and subtyping are accomplished by Western blot (WB) or ELISAs based on HTLV-I whole viral antigens and/or HTLV-I and HTLV-IIA peptides. The sensitivity and specificity of these serologic assays were compared to those of HTLV-I and-II-specific polymerase chain reaction (PCR) assays in tests on samples from Indians from South America in whom the HTLV-IIB subtype is endemic. STUDY DESIGN AND METHODS: Sera from 246 Gran Chaco Indians were evaluated for HTLV antibodies with the use of four ELISAs (Retrotek HTLV-I; Cambridge Biotech rgp21 enhanced HTLV-I/II; Vironostika HTLV-I/II; and Select HTLV-I/II), and a WB assay. Peripheral blood leukocyte DNA from each Indian was analyzed for HTLV-I or HTLV-II pol DNA via PCR. Fifteen of the PCR-positive samples were further subtyped via cloning and sequencing and/or oligomer restriction. RESULTS: Ninety-seven samples (39%) were positive for HTLV-II by serologic and/or PCR assays. All 15 positive DNA samples that were further analyzed were of the HTLV-IIB subtype and were clustered as a highly conserved phylogenetic group. Comparative analyses indicate that the sensitivity and specificity of the various assays were: PCR, 97 and 100 percent; Retrotek, 70 and 91 percent; Cambridge Biotech, 74 and 96 percent; Vironostika, 73 and 99 percent; Select 72 and 98 percent; and WB, 70 and 100 percent. CONCLUSION: The sensitivities of the tested HTLV serologic assays were comparable. However, the specificity of the Retrotek ELISA was significantly lower than that of the others. When positive, the subtyping assays were very specific. However, PCR assays would seem preferable or to be a necessary adjunct for the sensitive detection of HTLV-IIB infection.

Immunogenetics of HTLV-I/II and associated diseases.

The ethnic background of human T-lymphotropic virus types I and II (HTLV-I/II) infections and associated diseases was investigated in association with human leukocyte antigens (HLA) (alleles) and haplotypes. Japanese HTLV-I carriers were characterized by two categories of HLA class I antigens (A24, A26, B7, B61, Cw1, and Cw7) and class II alleles (DRB1 *0101, 0803, 1403, 1501, and 1502 and DQB1 *0303, 0501, and 0601); one category was associated with adult T-cell leukemia (ATL) patients and the other with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients. The ATL-associated haplotypes had unique DRB1-DQB1 alleles (0901-0303, 1501-0602, 1401-0503), which were correlated with a low immune responsiveness to HTLV-I, while the HAM/TSP haplotypes had different DRB1-DQB1 alleles (0101-0501, 0803-0601, 1502-0601), which were correlated with a high immune responsiveness to HTLV-I. Both ATL- and HAM/TSP-associated haplotypes were found among HTLV-I carriers and the patients from other ethnic groups (Jamaican blacks, Andes natives, South American mestizos, and Mashhadi Jews). HLA haplotypes of HTLV-II carriers were different from those of HTLV-I carriers among South American natives. These results suggested that HTLV-I/II infections and the associated diseases might be determined by immunogenetic factors segregated with HLA alleles and haplotypes.

Quantification of HTLV-II proviral copies by competitive polymerase chain reaction in peripheral blood mononuclear cells of Italian injecting drug users, central Africans, and Amerindians.

To better correlate the burden of human T cell leukemia virus type I (HTLV-I) and type II (HTLV-II) infection with diagnostic and prognostic markers, we developed a new competitive polymerase chain reaction (PCR) assay for the quantitative determination of proviral copy numbers in infected cells. A competitive plasmid was constructed that carried a 112-bp fragment from a highly conserved region of the HTLV tax gene and that was further modified by inserting a sequence of 24 bp. This competitive PCR assay system can be used for the quantification of HTLV-I and HTLV-II proviral DNA as demonstrated by using HTLV-I- and HTLV-II-infected cell lines and/or patient material. We determined the HTLV-II proviral load in peripheral blood mononuclear cells (PBMCs) of 11 Italian injecting drug users (IDUs) infected by this virus and in PBMCs of 10 seropositive Amerindian and Central African individuals from endemically infected ethnic groups. A great variation was observed in the number of HTLV-II proviral sequences in the PBMCs of Italian drug abusers, ranging from 5-10 to 16,239 copies/10(5) cells. There was no clear-cut correlation between proviral load, CD8 count, stage of HIV-1 infection, and therapy. A considerable variation in HTLV-II proviral load was also observed in PBMCs of Amerindians and Central Africans with no correlation between the amount of HTLV-II provirus and the geographic origin of the infected individuals.

Prevalence of human T cell lymphotropic virus type II in American Indian populations of the southwestern United States.

We investigated the seroprevalence of human T cell lymphotropic virus type II (HTLV-II) using a screening enzyme-linked immunosorbent assay (ELISA) and immunoblot confirmation among the predominant tribes (Pueblo and Athapaskan) served by two large Indian Health Service facilities in New Mexico. Among persons being treated for sexually transmitted diseases, eight (3.2%) of 250 were seropositive for HTLV II, compared with eight (2.1%) of 385 women attending prenatal clinics. In a survey of unselected patients at one of the facilities, 15 (3.4%) of 446 were seropositive. Of 31 seropositive subjects, 25 were infected with HTLV-II and six infections could not be typed. Sera from nine (29%) of the 31 infected subjects had absorbance values less than the manufacturer's cutoff in the ELISA. Both Pueblo and Athapaskan groups had similar overall seroprevalences, but women tended to have a slightly higher seroprevalence than men, and seroprevalence tended to increase with age. These data show that HTLV-II infection is present among diverse groups of American Indians in the southwestern United States. Present ELISA screening tests, such as those used in this study, lack sensitivity to HTLV-II infection unless a reduced absorbance cutoff is used.

Human T-lymphotropic virus type II in Panamanian Guaymi Indians.

BACKGROUND: Currently, human T-lymphotropic virus type II (HTLV-II) is the most prevalent human retrovirus, detected in persons presenting to donate blood in the United States. Only scant information is available with which to counsel HTLV-II-seropositive deferred donors or other persons about the ways in which they may spread HTLV-II to others. STUDY DESIGN AND METHODS: To increase understanding of the modes of transmission of HTLV-II, a seroepidemiologic study was conducted among Panamanian Guaymi Indians, a recently identified focus of endemic HTLV-II infection. Subjects were tested for serologic evidence of infection by HTLV-II, HTLV type I, hepatitis B virus, and nine other infectious agents by enzyme immunoassays and specific confirmatory tests. RESULTS: Nine (8.3%) of 109 persons tested HTLV-II-seropositive. HTLV-II seropositivity was more likely in persons with serologic evidence of prior hepatitis B virus infection. Sexual contact with HTLV-II-seropositive partners, but neither parenteral exposure nor breast-feeding, was identified as a risk factor for HTLV-II. CONCLUSION: In Guaymi Indians, HTLV-II appears to be spread primarily through sexual transmission.