Antibody to HTLV-I in indigenous inhabitants of the Andes and Amazon regions in Colombia

Human T-Cell Lymphotropic Virus Type 1 and associated diseases in Latin America

This narrative review, which is based on a systematic literature search following the PRISMA guidelines, provides a general overview of Human T-cell Lymphotropic Virus type 1 (HTLV-1) and associated diseases: Adult T-cell Leukaemia-Lymphoma (ATLL) and HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) in Latin America, focusing on epidemiology and prevention. Using the published information on HTLV-1, ATLL and HAM/TSP prevalence, we present comprehensive and accurate maps and tables, and developed an algorithm to assist in the prevention of HTLV-1 transmission through breastfeeding while considering socio-economic status. Latin America is an interesting scenario to study HTLV-1 because of the diverse origin of its population. Apart from the expected high prevalence in inhabitants of African ancestry, the presence of endemic foci affecting indigenous populations is particularly striking. ATLL prevention is the biggest challenge in this field. Most ATLL cases are transmitted through breastfeeding; thus, prevention methods to avoid ATLL in endemic countries have to be focused on this. In view of the high inequality in most Latin American countries, reduction in breastfeeding duration, freezing/thawing and pasteurisation of breastmilk can be suitable interventions in poor settings, considering that avoiding the risk of malnutrition and infant mortality must be the priority.

Prevalence of human T-cell lymphotropic virus I and II in Colombian blood donors, 2001-2014: Implications for transfusion safety

INTRODUCTION

The human T-cell lymphotropic virus (HTLV) 1 and 2 cause various clinical disorders associated with degenerative diseases. Blood transfusion is a primary mechanism of transmission that is associated with the use of cellular components such as red blood cells. 

OBJECTIVE

To describe the epidemiology of HTLV 1 and 2 in blood donors in Colombia from 2001-2014. 

MATERIALS AND METHODS

A retrospective analysis was performed using screening, reactivity and positivity for HTLV 1 and 2 data collected from 2001 to 2014 by Colombian blood banks and consolidated by the Instituto Nacional de Salud. Using this information, transfusion-associated infectivity was also estimated. 

RESULTS

From 2001 to 2014, 60.2% of blood collected in Colombia was screened for HTLV 1 and 2 and had a cumulative reactivity of 0.30%. This was 20 times higher in Chocó (6.28%), where blood collection ended in 2004. Blood screening for HTLV reached 94.9% in 2014 with a positive concordance of 14.7%, and an estimated 406 unscreened, potentially infectious blood units were released. The majority of the unscreened blood units (215 units, 53%) came from Antioquia, a non-endemic department. 

CONCLUSION

These results suggest that HTLV 1 and 2 infections are distributed in different areas of the country that were not previously classified as endemic. These findings support the importance of the universal screening of blood units to minimize the risk of infection through transfusion for this event.

Origin and prevalence of human T-lymphotropic virus type 1 (HTLV-1) and type 2 (HTLV-2) among indigenous populations in the Americas

Human T-lymphotropic virus type 1 (HTLV-1) is found in indigenous peoples of the Pacific Islands and the Americas, whereas type 2 (HTLV-2) is widely distributed among the indigenous peoples of the Americas, where it appears to be more prevalent than HTLV-1, and in some tribes of Central Africa. HTLV-2 is considered ancestral in the Americas and is transmitted to the general population and injection drug users from the indigenous population. In the Americas, HTLV-1 has more than one origin, being brought by immigrants in the Paleolithic period through the Bering Strait, through slave trade during the colonial period, and through Japanese immigration from the early 20^th century, whereas HTLV-2 was only brought by immigrants through the Bering Strait. The endemicity of HTLV-2 among the indigenous people of Brazil makes the Brazilian Amazon the largest endemic area in the world for its occurrence. A review of HTLV-1 in all Brazilian tribes supports the African origin of HTLV-1 in Brazil. The risk of hyperendemicity in these epidemiologically closed populations and transmission to other populations reinforces the importance of public health interventions for HTLV control, including the recognition of the infection among reportable diseases and events.

Ethnoepidemiology of HTLV-1 related diseases: ethnic determinants of HTLV-1 susceptibility and its worldwide dispersal

Human T-cell lymphotropic virus type 1 is vertically transmitted in neonatal life and is causatively associated with adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in adults. Persistence of HTLV-1 in host T cells, clonal expansion of the HTLV-1 carrying T cells, and emergence of malignantly transformed T cells are in accord with the multistep model of human cancer and roles for continuous interaction between host genes and environmental factors. This article reviews two lines of HTLV-1 investigation, one regarding worldwide surveillance of HTLV-1 infection foci by serological testing and molecular analysis of HTLV-1 isolates, and the other focusing on genetics of the human leukocyte antigen (HLA) that determines the ethnic background of HTLV-1 permissiveness and susceptibility to ATL or HAM/TSP. The serological surveillance revealed transcontinental dispersal of HTLV-1 in the prehistoric era that started out of Africa, spread to Austro-Melanesia and the Asian continent, then moved to North America and through to the southern edge of South America. This was highlighted by an Andean mummy study that proved ancient migration of paleo-mongoloid HTLV-1 from Asia to South America. Phylogenetic analysis of HLA alleles provided a basis for ethnic susceptibility to HTLV-1 infection and associated diseases, both ATL and HAM/TSP. Ethnicity-based sampling of peripheral blood lymphocytes has great potential for genome-wide association studies to illuminate ethnically defined host factors for viral oncogenesis with reference to HTLV-1 and other pathogenic elements causatively associated with chronic disease and malignancies.

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.

HTLV-I infection associated with disease in aboriginal Indians from British Columbia: a serological and PCR analysis

BACKGROUND

Recent epidemiology studies have demonstrated the presence of HTLV-I and its close relative, HTLV-II in several aboriginal populations in North, Central and South America but not in Canadian Indian populations. HTLV-II appears to be more prevalent than HTLV-I in aboriginal populations of the Americas. Recently several clinical cases of HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP) and a case of adult T-cell leukemia (ATL) have been identified in British Columbian Indians. This data suggests that a new endemic area of HTLV-I infection may be present within British Columbian Indian population. However, it has recently been shown that HTLV-II may also be associated with a neurological disease similar to HAM/TSP.

OBJECTIVES

The purpose of the work reported here was to demonstrate whether HTLV-I, HTLV-II or both were responsible for the diseases seen in the British Columbian Indians.

STUDY DESIGN

In this study serological and gene amplification techniques were used to determine whether HTLV-I or HTLV-II was present in four families and three unrelated individuals all from different bands of aboriginal Native Indians in British Columbia. In each family, one member had an HTLV-associated disease, three cases of HAM/TSP and one case of ATL. Of the three individual aboriginal natives unrelated to the four families, two had HAM/TSP while the third was asymptomatic for HTLV-associated diseases.

RESULTS

This study demonstrated the presence of HTLV-I in the aboriginal Indians with disease and in some of their family members. HTLV-II was not detected in any of the British Columbian Indians tested in this study.

CONCLUSIONS

These British Columbian Indians represent the first Canadian aboriginal Indians with HTLV-I infection and associated diseases. Furthermore, the British Columbian Indian population may represent a previously unrecognized endemic population of HTLV-I infection.

Differences in viral and host genetic risk factors for development of human T-cell lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis between Iranian and Japanese HTLV-1-infected individuals

Human T-cell lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a neurological disease observed only in 1–2 % of infected individuals. HTLV-1 provirus load, certain HLA alleles and HTLV-1 tax subgroups are reported to be associated with different levels of risk for HAM/TSP in Kagoshima, Japan. Here, it was determined whether these risk factors were also valid for HTLV-1-infected individuals in Mashhad in northeastern Iran, another region of endemic HTLV-1 infection. In Iranian HTLV-1-infected individuals (n=132, 58 HAM/TSP patients and 74 seropositive asymptomatic carriers), although HLA-DRB1*0101 was associated with disease susceptibility in the absence of HLA-A*02 (P=0·038; odds ratio=2·71) as observed in Kagoshima, HLA-A*02 and HLA-Cw*08 had no effect on either the risk of developing HAM/TSP or HTLV-1 provirus load. All Iranian subjects possessed tax subgroup A sequences, and the protective effects of HLA-A*02 were observed only in Kagoshima subjects with tax subgroup B but not in those with tax subgroup A. Both the prevalence of HTLV-1 subgroups and the host genetic background may explain the different risks levels for HAM/TSP development in these two populations.

Seroprevalence and risk factors for human T-cell lymphotropic virus (HTLV-I) infection among ethnically and geographically diverse Peruvian women

OBJECTIVE

To assess the seroprevalence and risk factors for HTLV-I infection in Peruvian women.

METHODS

Five hundred and sixty-eight healthy women >20 years of age from three Peruvian regions were randomly selected and screened for HTLV-I. ELISA-reactive sera were confirmed via immunofluorescence assay, recombinant immunoblot assay, Western blot, and PCR. Women from Huanta (n=303), an Andean city inhabited by indigenous Quechuans, El Carmen (n=132), a primarily African-American coastal town, and Lima (n=133), with its Mestizo population, were selected.

RESULTS

HTLV-I antibodies were present in 2.5% (14/568) of women (1.3% in Huanta, 3.8% in El Carmen, and 3.8% in Lima); 2.5%, 2.7% and 2.6% of Quechuans, Mestizas and African-Americans, respectively, were infected. History of a blood transfusion (P <0.00002), chronic scabies (P <0.02), having a relative with leukemia (P <0.04), age +/- 38 years (P <0.03), young age at first intercourse (P <0.04), lifetime partners >4 (P <0.04), educational status (P <0.02) and >4 pregnancies (P <0.03) were significantly associated with infection.

CONCLUSIONS

HTLV-I is endemic among asymptomatic Peruvian women. Parenteral, vertical and heterosexual transmission are associated with infection.

Risk of transfusion-transmitted human T-cell lymphotropic virus-type I in Latin America

In a recent publication, G. Schmunis et al presented data from Latin America on blood quality and on important approaches to preventing human immmunodeficiency virus (HIV), acquired immunodeficiency syndrome (AIDS), and other infectious diseases that may be transmitted by blood transfusion. Mass screening between 1987 and 1988 in Peru of blood from more than 90,000 donors highlighted potential problems in the donor population, and it also uncovered inappropriate practices related to the use of blood transfusions. Since then, adequate screening of the blood supply for HIV was implemented and new transfusion-related AIDS cases have been prevented during the past 8 years.

Human T-cell lymphotropic virus-I in Latin America

HTLV-1 infection is endemic in several Latin American countries. HTLV-1-associated myelophathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukemia lymphoma (ATLL) are emerging diseases in the region. Documented risk factors for acquiring the virus include breast-feeding, contaminated blood transfusion, and sexual intercourse, all of which are amenable to prevention efforts. Strongyloides stercoralis hyperinfection syndrome and therapeutic failure in apparently healthy patients with nondisseminated strongyloidiasis may be markers of HTLV-1 infection. HTLV-1 co-infection may adversely effect the clinical course of scabies and HIV disease. The new enzyme-linked immunosorbent assays (ELISA) are sensitive and specific, and Western blot technology is reliable for differentiating HTLV-1 from less common HTLV-2. HTLV-1 screening of blood donors and individuals with any disorder that suggests infection has become a necessity in Latin America to prevent the spread of this important emerging pathogen.

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-I infection among relatives of patients with adult T-cell leukemia/lymphoma in Brazil: analysis of infection transmission

We examined the presence of HTLV-I infection among 66 family members of 13 patients with well documented ATL to investigate the routes of HLTV-I transmission in a Southeast region of Brazil. HTLV-I infection was screened by an enzyme immunossay (ELISA) test and all repeatedly positive or indeterminate ELISA samples were further tested by a Western-Blot (WB) technique. Indeterminate and inconclusive WB samples were confirmed by a polymerase chain reaction (PCR). ELISA results showed that 40 (60.6%) individuals were not infected; 16 (24.2%) were positive; and 10 (15.2%) were undetermined. Among 16 ELISA positive subjects, 14 (87.5%) were confirmed to be positive by WB while 2 (12.5%) showed inconclusive results. Based on the laboratory data, questionnaire analysis, and family/epidemiological studies, we concluded that HTLV-I vertical transmission occurred in 6 of the 13 families. In 3 of these 6 families, the horizontal transmission also could be demonstrated. An isolated horizontal transmission was detected in one family, and in 6 families we did not find any infected family member. All HTLV-I-infected persons were clinically asymptomatic. The occurrence of an effective HTLV-I vertical transmission detected by the present study suggest that HTLV-I infection is endemic in the Southeast region of Brazil. Consistent with the modes of transmission, the HTLV-I antibody seroprevalence was greater in relatives of ATL patients than in the general blood donor Brazilian population (0.4%). In addition, the present data suggest that HTLV-I carries a high infectivity rate but a low virulence.

The origin and evolution of human T-cell lymphotropic virus types I and II

Studies on human T-cell lymphotropic virus types I (HTLV-I) and II (HTLV-II) are briefly reviewed from the viewpoint of molecular evolution, with special reference to the evolutionary rate and evolutionary relationships among these viruses. In particular, it appears that, in contrast to the low level of variability of HTLV-I among different isolates, individual isolates form quasispecies structures. Elucidating the mechanisms connecting these two phenomena will be one of the future problems in the study of the molecular evolution of HTLV-I and HTLV-II.

Prevalence and phylogenetic analysis of HTLV-I isolates in Cameroon, including those of the Baka Pygmy

Our previous analysis of an HTLV-I isolate (CMR229) from a Cameroonian Pygmy demonstrated that the isolate is distinct from typical HTLV-Is of the "Central African group," which has a close similarity to HTLV-I-related simian viruses (STLV-I) in Africa. In this study, we analyzed six new HTLV-Is from Cameroon consisting of three isolates from the Pygmy and three from the Bantu to examine further the genetic features of HTLV-I in Cameroon, especially in the Pygmy. A phylogenetic tree based on the long terminal repeats (LTR) region showed that all the new HTLV-Is belong to the Central African group. On the other hand, an env-based analysis of CMR229 confirmed the previous finding derived from LTR-based analysis that CMR229 has a similarity to African STLV-Is, but is distinct from the typical Central African group of HTLV-I. This suggests that multiple interspecies transmissions from non-human primates to humans have occurred in Central Africa, resulting in the presence of two distinct HTLV-I strains in this area. In addition, it seems likely that the Pygmy harbors the heterogeneous HTLV-I strains from which the main HTLV-I population spread into the Bantu.

Ethnic segregation of HTLV-I and HTLV-II carriers among South American native Indians

To investigate the genetic background of human T-cell leukemia virus type I (HTLV-I) and II (HTLV-II) carriers among South American native Indians, we analyzed HLA DRB1*-DQB1* haplotypes of the virus carriers from Andes highlands and Orinoco lowlands by the PCR-RFLP genotyping method. It was revealed that the HTLV-I-carrying Andes natives had one of the 5 HLA haplotypes: DRB1*-DQB1* 0403-0302, 0802-0402, 0901-0303, 1406-0302 and 0407-0302, and that the Orinoco HTLV-II carriers had one of the 3 HLA haplotypes: DRB1*-DQB1* 1402-0301, 1602-0301 and 0404-0302. The HLA haplotypes of Andes HTLV-I carriers and Orinoco HTLV-II carriers were mutually exclusive. The haplotypes associated with HTLV-I carriers were commonly found among the Andes Indians and Japanese, which is the known HTLV-I endemic population, while the haplotypes associated with HTLV-II carriers were specifically found among the Orinoco Indians and North American Indians, among whom HTLV-II is endemic. These results suggested that HLA haplotypes might be ethnically segregated among South American natives and might be involved in the susceptibility to HTLV-I and HTLV-II infections.

Human T-lymphotropic virus type 1 in coastal natives of British Columbia: phylogenetic affinities and possible origins

Human T-lymphotropic virus type 1 (HTLV-1) infection has been discovered recently in people of Amerindian descent living in coastal areas of British Columbia, Canada. DNA sequencing combined with phylogenetic analysis and restriction fragment length polymorphism (RFLP) typing of HTLV-1 strains recovered from these British Columbia Indians (BCI) was conducted. Sequence-based phylogenetic trees distributed the BCI isolates among the Japanese subcluster (subcluster B) and the geographically widely distributed subcluster (subcluster A) of the large HTLV-1 cosmopolitan cluster. Long terminal repeat (LTR) RFLP typing revealed three distinct, equally frequent LTR cleavage patterns, two of which were of previously recognized Japanese and widely dispersed cosmopolitan types. A third, new cleavage pattern was detected which may have arisen by recombination between two other HTLV-1 genotypes. Our results suggest multiple origins for HTLV-1 in BCI, which are equally consistent with (i) a cluster of recent sporadic infections, (ii) ancient endemic vertical transmission through Amerindian lineages, or (iii) both.

HTLV-I from Iranian Mashhadi Jews in Israel is phylogenetically related to that of Japan, India, and South America rather than to that of Africa and Melanesia

A new endemic focus of human T-lymphotropic virus type I (HTLV-I) was recently reported among Mashhadi Jews, a group of immigrants from northeastern Iran to Israel. We extracted DNAs from fresh peripheral blood mononuclear cells (PBMCs) and/or gargle mouthwash from 10 HTLV-I carriers, who consisted of members of one family, and HTLV-I-associated myelopathy (HAM) and adult T-cell leukemia (ATL) patients. Long terminal repeat (LTR) regions of proviral DNAs were sequenced and analyzed phylogenetically. In a phylogenetic tree, all the Mashhadi HTLV-I isolates belonged to subtype A, one of the three subtypes of the cosmopolitan type of HTLV-I, and made a tight cluster distinct from the other isolates of subtype A from Japan, India, the Caribbean Basin, and South America. Although a few nucleotide substitutions were observed among the clones sequenced, no characteristic sequence variation was found in different disease manifestations, even in one family or different sources of DNA preparation.

Southernmost carriers of HTLV-I/II in the world

To clarify the real distribution of HTLV-I and -II carriers among indigenous people in central and South America, blood samples collected from indigenous people in isolated regions of Southern Chile were examined. Among 199 inhabitants from Chiloe Island and Pitrufquen town, three cases (1.5%) showed positive anti-HTLV-I antibodies. Two out of the three (82-year-old male and 58-year-old female) reacted to HTLV-II-specific Gag and/or Env proteins but not to HTLV-I-specific ones. The latter case was confirmed as an HTLV-II carrier by polymerase chain reaction test.

Nucleotide sequence analysis of an HTLV-I isolate from a Chilean patient with HAM/TSP

Isolates of HTLV-I have been characterized from a number of different regions of the world; however, there has not been a nucleotide sequence analysis of an HTLV-I isolate from a South American country. Reported here is an individual from Chile identified with the HTLV-I-associated neurological disease HAM/TSP. The sera and the nucleic acid sequence of the HTLV-I present in peripheral blood lymphocytes from this Chilean HAM/TSP patient over a two year period are characterized. During this time, the patient's condition grew progressively worse. While the serological profile of this patient was unremarkable in comparison with other HAM/TSP patients previously described, nucleic acid sequence analysis identified two nucleotide positions which contained nucleotides unique to this Chilean isolate. The nucleotide sequence analysis also indicates that the Chilean HTLV-I isolate is more closely related to Caribbean and Japanese isolates of HTLV-I than to the African and U.S. isolates described so far.