Incidence of retroviruses in some Brazilian groups

Long-term prevalence follow-up (1967-2022) of HTLV-2 among vulnerable indigenous populations in the Amazon region of Brazil

Introduction

Human T-lymphotropic virus 2 (HTLV-2) has been described for more than 30 years as an endemic infection in Brazilian indigenous populations, with its occurrence varying by age and sex, maintained mainly by sexual intercourse and mother-to-child transmission, favoring intrafamilial aggregation.

Methods

The epidemiological scenario of HTLV-2 infection has been described among communities of the Amazon region of Brazil (ARB), with the number of retrospective positive blood samples increasing for more than 50 years.

Results

Five publications were selected that showed the presence of HTLV-2 in 24 of 41 communities; the prevalence of infection was described among 5,429 individuals at five points in time. Among the Kayapó villages, the prevalence rates were described according to age and sex and reached up to 41.2%. Three communities (Asurini, Araweté, and Kaapor) were kept virus free for 27 to 38 years of surveillance. Low, medium and high prevalence levels of infection were defined, and two pockets of high endemicity were shown in the state of Pará, pointing to the Kikretum and Kubenkokrê Kayapó villages as the epicenter of HTLV-2 in the ARB.

Discussion

The prevalence rates over the years have shown a decline among the Kayapó (from 37.8 to 18.4%) and an apparent change to a higher prevalence among females, but not during the first decade of life, usually associated with transmission from mother to child. Sociocultural and behavioral aspects, as well as public health policies directed toward sexually transmitted infections, might have positively influenced the decline in HTLV-2 infections.

Moderate prevalence of transmitted drug resistance and interiorization of HIV type 1 subtype C in the inland North State of Tocantins, Brazil

The diverse Brazilian AIDS epidemic has reached small cities and scant molecular information is available about the epidemic in Northern Brazil, where the incidence is growing. This study describes transmitted drug resistance and subtypes in the protease (PR) and reverse transcriptase (RT) regions among naive patients recruited in Palmas, the capital of Tocantins State, a newly built city in Northern Brazil. PR/RT regions were retrotranscribed from plasma HIV-1 RNA and 52 were sequenced after direct nested PCR. HIV-1 subtypes were assigned by phylogenetic analysis. Transmitted drug resistance was analyzed by the Calibrated Population Resistance tool Stanford Surveillance Drug Resistance Mutation. Most patients included (59.6%) were males, the median age was 30 years and were mainly referred because of heterosexual or homosexual unprotected sex. One male patient was from the Karajás indigenous tribe. The prevalence of transmitted resistance was 11.5% (CI 95%, 4.4-23.4%): nonnucleoside RT inhibitor mutations (n=3), nucleoside RT inhibitor mutations (n=2), and protease inhibitor mutations (n=1). Dual or triple class resistance was not observed. HIV-1 subtype B(PR)/B(RT) represented 78.8%, 5.8% were subtype C(PR)/C(RT), and 1.9% were subtype F1(PR)/F1(RT). Recombinant viruses represented 13.5% (07/52): B(PR)/F1(RT) (n=1), B(PR)/BF1(RT) (n=4), and C(PR)/CF1(RT) (n=2). This study about the AIDS epidemic in the recently founded city of Palmas/Tocantins in inland Northern Brazil shows moderate levels of transmitted drug resistance and the circulation of diverse recombinant viruses. This pattern is similar to what has been described in major metropolitan cities, suggesting the influence of imported cases from the south/southeast. Moreover these results indicate that patients from this setting should be monitored regarding transmitted drug resistance mutations.

HUMAN RIGHTS, BIOMEDICAL SCIENCE, AND INFECTIOUS DISEASES AMONG SOUTH AMERICAN INDIGENOUS GROUPS

Despite the efforts of international health agencies to reduce global health inequalities, indigenous populations around the world remain largely unaffected by such initiatives. This chapter reviews the biomedical literature indexed by the PubMed database published between 1963 and 2003 on South American indigenous populations, a total of 1864 studies that include 63,563 study participants. Some language family groupings are better represented than are others, and lowland groups are better represented than are highland groups. Very few studies focus on major health threats (e.g., tuberculosis, influenza), public health interventions, or mestizo-indigenous epidemiological comparisons. The prevalence rates of three frequently studied infections—parasitism, human T-cell lymphotropic viral infection (HTLV), and hepatitis—are extraordinarily high, but these facts have been overlooked by national and international health agencies. This review underscores the urgent need for interventions based on known disease prevalence rates to reduce the burden of infectious diseases in indigenous communities.

Tropical dermatology: viral tropical diseases

Viruses are important pathogens in tropical areas; most of them, especially the tropical hemorrhagic fevers, produce mucocutaneous manifestations. More than any other kind of pathogen, viruses have the possibility for being widespread, since they have a greater probability of mutation than do bacteria, can cross species barriers easily, and infect both human beings and animals in habitats with a great biodiversity. Tropical habitats also have been subject to major ecologic changes in the last few decades, exposing humans to direct contact with these viruses and allowing hemorrhagic fevers due to new emergent viruses such as flaviviruses, filoviruses, arenaviruses, and hantaviruses to become major threats to public health. The collapse of eradication programs in many countries, as well as population increases and ecologic modifications, have led to the spread of dengue and yellow fever to large portions of the world owing to the dissemination of vectors, especially mosquitoes, with broad ecologic ranges. Viruses previously restricted to some geographic areas, such as Rift Valley fever, Crimean-Congo hemorrhagic fever, West Nile fever, and monkeypox are now affecting new countries and populations. Other viruses such as herpes B infection often affect travelers and animal handlers in most parts of the world. Dermatologic lesions occur in all these diseases and can facilitate a rapid diagnosis, leading to control of the virus and helping prevent possible outbreaks.

Human retroviruses (HIV and HTLV) in Brazilian Indians: seroepidemiological study and molecular epidemiology of HTLV type 2 isolates

To investigate serological, epidemiological, and molecular aspects of HTLV-1, HTLV-2, and HIV-1 infections in Amerindian populations in Brazil, we tested 683 and 321 sera from Tiriyo and Waiampi Indians, respectively. Both HIV-1 and HTLV-2 infections were detected at low prevalence among the Tiriyos whereas only HTLV-1 was present among the Waiampis, also at low prevalence. Analysis of the nucleotide sequence of the 631 bp of the env gene obtained from the three HTLV-2 isolates detected among the Tiriyos demonstrated by restriction fragment length polymorphism that these viruses belong to subtype IIa. Phylogenetic analysis of this same fragment showed that these sequences cluster closer to HTLV-2 isolates from intravenous drug users living in urban areas of southern Brazil than to the same gene sequence studied in another Brazilian tribe, the Kayapos. Our results confirm the distribution of Brazilian HTLV-2 sequences in a unique cluster I and cluster IIa and suggest that there is a considerable degree of diversity within this cluster. We also report for the first time HIV-1 infection among Brazilian Amerindians.

The HIV epidemic in the Amazon Basin is driven by prototypic and recombinant HIV-1 subtypes B and F

This paper describes genetic subtypes of HIV-1 found in blood samples from 31 HIV-1-infected people who visited the Counseling and Testing AIDS Center of Instituto de Medicina Tropical in Manaus, Brazil. Manaus, the main city in Brazil's Amazon Basin, is also the closest urban connection for more than 100,000 Indians living in the rain forests of this region. Although to date there is no evidence of increased incidence of HIV-1 infection among the indigenous population, our understanding of both the prevalence and nature of the epidemic in the region as a whole is limited. From the 31 samples analyzed by C2V3 sequencing, we found almost equal proportions of HIV-1 strains belonging to subtype B (n = 16; 51.6%) and subtype F (n = 15; 48.4%), a finding that differs from results from previous studies conducted in urban areas of southeastern Brazil. We also observed the presence of the GWGR amino-acid sequence in the critical tetra-peptide crown of the env V3 loop in the HIV-1 subtype B samples analyzed. Among these samples, we also found 14 mosaic genomes (45.16%) in which different combinations of subtypes B, C, and F were identified between the p24 gag, pro, and env regions. Our data support the hypothesis that the Amazonian HIV-1 infections linked to the urban epidemic in southeastern Brazil. The genetic diversity and the prevalence of mosaic genomes among the isolates in our study confirm an integral role of recombination in the complex Brazilian epidemic.

[HTLV-I/II infection in the state of Bahia]

The city of Salvador, capital of Bahia, presents a population with the highest prevalence of HTLV-I infection in Brazil. Until now, only one study has investigated this infection in other cities of this state, even though by using a small sample. With objective to evaluate the prevalence of HTLV-I/II antibodies in four cities of the state of Bahia. Serum samples from 1,539 individuals who lived in Catolândia, Ipupiara, Jacobina and Prado were screened by ELISA, and repeatedly reactive samples confirmed by Western Blot. Forty-seven (3.1%) samples were positive by ELISA, and 44 of them were tested by Western blot: 5 (0.3%) were positive, 8 (0.5%) were indeterminate (all of them from Jacobina) and 31 were negative. The overall prevalence of HTLV-I antibodies was 0.3%. This prevalence varied from 0.0% (Prado) to 0.7% (Jacobina), but differences were not statistically significant (p > 0.21). None of these individuals presented HTLV-II antibodies. Jacobina showed the highest prevalence of HTLV-I infection among the cities studied, although the overall prevalence was low. In conclusion, further epidemiological, clinical and virological studies will be of paramount importance to obtain a better understanding of the natural history of this infection in Jacobina.

HTLV-I infection and adult T-cell leukemia in Brazil: an overview

Human T-cell lymphotropic Virus Type I (HTLV-I) is the etiologic factor for adult T-cell leukemia/lymphoma (ATL). HTLV-I infection can also lead to other diseases, such as HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), uveitis, arthropathy and infectious dermatitis. Studies of the infectious mode of transmission of HTLV-I and risk factors for HTLV-I-related diseases have been conducted in several countries, and differences in the prevalence, age patterns, ethnic groups and clinical presentation of the related diseases have been described worldwide. Based on the geographical characteristics of Brazil and data from the literature, we have summarized the distribution of seroprevalence in blood donors in different states around the country, as well as the incidence of ATL in regards to the endemic foci. ATL in Brazil has the same characteristics as those described elsewhere, but is reported more frequently at a younger age. In order to better evaluate ATL in Brazil, a registry has been established at the several hematologic centers under the sponsorship of the instituto Nacional de Cancer and the Brazilian Society of Hematology and Hemotherapy, for the purpose of recording all cases originally diagnosed in Brazil.

Molecular characterization of human immunodeficiency virus type 1 isolates from Venezuela

Eight HIV-1 isolates from Venezuela have been characterized by nucleotide sequencing of the entire reverse transcriptase (RT)- and surface glycoprotein (gp 120)-coding regions. Average mutant frequencies were 2.5 x 10(-2) substitutions per nucleotide (s/nt) for the RT-coding region, and 10 x 10(-2) or 6.8 x 10(-2) s/nt for the gp120-coding region, depending on whether gaps introduced for optimal alignment were or were not, respectively, considered in the calculations. Phylogenetic trees were derived by maximum-likelihood, neighbor-joining, and maximum parsimony methods. In the trees derived from both RT- and gp120-coding regions, Venezuelan isolates cluster with subtype B viruses. However, the relative position of some of the isolates is considerably different in the two trees. Unique V3 loop amino acid sequences, not represented in the current database, have been identified among the Venezuelan isolates. In addition to representing the first molecular characterization of HIV-1 from Venezuela, the extensive genetic heterogeneity observed reinforces the interest in characterizing additional HIV-1 isolates worldwide for adequate vaccine design.

HTLV-negative and HTLV type I-positive tropical spastic paraparesis in northeastern Brazil

A type-specific serological survey among 1042 random nonneurological outpatients in two cities in the state of Ceara (northeastern Brazil) shows a low prevalence of HTLV-I (0.34% in Fortaleza; 0.44% in Crato) and of HTLV-II (0.34% in Fortaleza; 0% in Crato). Among 62 chronic myelopathic patients seen in Fortaleza 27 patients were found with clinical features of tropical spastic paraparesis (TSP); 10 of 27 were found HTLV-I seropositive (37%; 95% confidence limits, 19-58%). Proviral genome detection by polymerase chain reaction in 5 seropositive and 12 seronegative patients confirmed the serological findings. This excludes HTLV-I or -II infection as a cause in the seronegative TSP patients. The HTLV-positive and -negative patients did not differ clinically and by history, except that seropositives had a longer mean disease duration, a female predominance, and a higher proportion of white Caucasians. In this population with low HTLV-I and HTLV-II prevalences, HTLV-negative TSP is at least as frequent as the HTLV-I-associated TSP.

Clinical and demographic features of HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) in Rio de Janeiro, Brazil

In Rio de Janeiro (RJ) most cases of paraparesis of obscure origin are associated with the human T-cell lymphotropic virus type I (HTLV-I). Thirty-four consecutive patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) from RJ were evaluated. Most patients came from low socio-economic levels. There was no difference in terms of gender. The main affected racial group was white. A history of sexually transmitted diseases was a major risk factor for HAM/TSP and a positive serology for syphilis was found in 26.5% of the patients. The major clinical findings were of a spastic paraparesis with generalized brisk tendon jerks and bilateral Babinki's sign. Sensation was abnormal in 25 patients (73.5%) and five (14.7%) had a sensory level. Three patients (8.8%) had optic atrophy. The cerebrospinal fluid showed a lymphocytic pleocytosis with a mean total protein content of 0.4 g/litre, and an increased intrathecal IgG synthesis in 59.4% of patients. HAM/TSP and multiple sclerosis (MS) occur indigenously in RJ and some HAM/TSP cases can be sometimes confused with MS. Therefore we propose that, in places where MS coexist with HAM/TSP, HTLV-I antibodies should be sought routinely in those MS suspected cases with prominent spastic paraparesis.

[The epidemiological aspects of HIV/AIDS in Brazil]

A trend analysis of the AIDS epidemics in Brazil is presented, emphasizing temporal changes among the population groups most affected. Regional comparisons as well as projections of the extension of HIV infection and AIDS cases are also reported. Amongst the most relevant conclusions the alarming increase of cases in heterosexual populations and intravenous drug users is emphasised, specially in the southeast region.

Antibody to human T-lymphotropic virus in a patient with Guillain-Barré syndrome (case report)

Serum sample obtained from a male, 12 year old patient suffering from Guillain-Barré syndrome (GBS) was positive for human T-lymphotropic virus (HTLV-I) antibody by the enzyme-linked immunosorbent assay (ELISA) and the Western Blot analysis (WB). Attempts to isolate enteroviruses (including poliovirus) from faecal material in both tissue culture and suckling mice were unsuccessful; in addition, acute and convalescent paired serum samples did not show any evidence of recent poliovirus infection when tested against the three serotypes. Specific tests for detection of Epstein-Barr virus infection were not performed; however, the Paul-Bunnel test yielded negative results. ELISA for detection of anti-cytomegalovirus IgM was also negative. The concomitant occurrence of either adult T cell leukemia (ATL) or lymphoma was not recorded in this case.

Prevalence of antibodies to HTLV-1 in South American Indians (Mapuches) from Chile

The seroprevalence of HTLV-1 antibodies was investigated in 405 serum samples from healthy South American Indians (Mapuches) from Chile, using enzyme linked immunoassay (ELISA), Western immunoblot (WB) and radioimmuno precipitation assay (RIPA). Six samples were positive by ELISA; 3 of them were confirmed by WB/RIPA. Thus, we observed a seroprevalence of 0.7% for HTLV-1 antibodies in healthy Mapuches.

Seroepidemiologic survey for antibodies to human retroviruses in human and non-human primates in Brazil

The prevalence of antibodies to HTLV-I and HIV-I in Brazil was determined by testing sera from: (a) 119 members of an isolated Amazonian community of African origin; (b) 100 voluntary blood donors in Rio de Janeiro; (c) 215 patients treated at the Hematology Service, National Cancer Institute, Rio de Janeiro, and (d) 44 Cebus apella New World monkeys, wild-caught in Amazonia. Anti-HTLV-I was detected in 1 (0.84%) of 119 Amazonians, in 8 (3.72%) of the 215 patients and in none of the blood donors or monkeys. The high prevalence found in patients included 4 (5.79%) of 69 with non-Hodgkin lymphoma, 2 (5.88%) of 34 with Hodgkin lymphoma, 1 (16.66%) of 6 patients with diagnosis of anemia and 1 (20%) of 5 with HIV-I infection. Anti-HIV-I was found in 7 (14.89%) of 47 patients and in none of the other groups. The high incidence of HTLV-I infection in the patient group suggests that this retrovirus is endemic in parts of Brazil.

HIV-1, HIV-2, and HTLV-I infection in high-risk groups in Brazil

We conducted a serologic survey for antibodies to human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2) and human T-cell lymphotropic virus Type I (HTLV-I) in 704 Brazilians with the acquired immunodeficiency syndrome (AIDS) or at risk for it. The study population included 70 homosexual men (11 of whom were prostitutes), 58 bisexual men (19 of whom were prostitutes), 101 female prostitutes from three socioeconomic groups, 13 wives of men with hemophilia who were seropositive for HIV-1 antibodies, and 47 blood donors with positive Venereal Disease Research Laboratory tests for syphilis, all from Rio de Janeiro; 86 female prostitutes from two rural towns in Minas Gerais; 133 patients with AIDS from São Paulo; and 196 men with bleeding disorders who were seropositive for HIV-1 antibodies on enzyme-linked immunosorbent assay, from São Paulo and Rio de Janeiro. The prevalence of HIV-1 infection was highest in the homosexual male prostitutes (45 percent), the wives of patients with hemophilia (38 percent), the bisexual men (28 percent), the homosexual men who were not prostitutes (19 percent), and the female prostitutes from the lower class (9 percent). Combined HIV-1 and HIV-2 infection was found in 3 percent of the patients with AIDS and in 1 percent of the homosexual men. The prevalence of HTLV-I infection ranged from 1 percent in rural female prostitutes to 13 percent in HIV-1-positive men with bleeding disorders in Rio de Janeiro. Combined HIV-1 and HTLV-I infection occurred in 1 to 11 percent of some male subgroups. We conclude that in Brazil HIV-1 infection is already well established among homosexuals, bisexuals, and lower-class female prostitutes, with bisexual men probably acting as a bridge between the heterosexual and homosexual communities, that HTLV-I infection is prevalent in groups at risk for AIDS, and that HIV-2 infection has already been introduced into the country.