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

Ricardo Ishak; Marluísa de Oliveira Guimarães Ishak; Isabella Nogueira Abreu; Luiz Fernando Almeida Machado; Sandra Souza Lima; Maria Alice Freitas Queiroz; Izaura Maria Cayres-Vallinoto; João Farias Guerreiro; Antonio Carlos Rosário Vallinoto

doi:10.3389/fmicb.2023.1217134

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

Front Microbiol. 2023 Jun 22:14:1217134. doi: 10.3389/fmicb.2023.1217134. eCollection 2023.

Affiliations

¹ Laboratory of Virology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil.
² Postgraduate Program in Biology of Infectious and Parasitic Agents, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil.
³ Laboratory of Human and Medical Genetics, Institute of Biological Sciences, Federal University of Pará, Belem, Pará, Brazil.

Abstract

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.

Keywords: Amazon; HTLV-1/2; epidemiology; indigenous; vulnerable population.