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. 2019 May 14:10:1002.
doi: 10.3389/fmicb.2019.01002. eCollection 2019.

Evidence of New Endemic Clusters of Human T-Cell Leukemia Virus (HTLV) Infection in Bahia, Brazil

Felicidade Mota Pereira  1   2 , Maria da Conceição Chagas de Almeida  3 , Fred Luciano Neves Santos  1 , Roberto Perez Carreiro  4 , Carlos Gustavo Regis-Silva  1 , Bernardo Galvão-Castro  1   5 , Maria Fernanda Rios Grassi  1   5
Affiliations

Evidence of New Endemic Clusters of Human T-Cell Leukemia Virus (HTLV) Infection in Bahia, Brazil

Felicidade Mota Pereira et al. Front Microbiol. .

Abstract

Background: Salvador, Bahia (northeastern Brazil), has been identified as the epicenter of Human T-cell leukemia virus Human T-cell leukemia virus (HTLV) type 1 infection in the country. This study aims to estimate the rate of HTLV infection and the geographical distribution of this virus in this state.

Methods: All HTLV tests (chemiluminescence/ELISA assays/Western Blotting) performed in the Central Laboratory of Public Health of Bahia (LACEN) from 2004 to 2013 were included. Data was extracted from LACEN's database using high volume extract, transformation and load throughput. Infection rate was expressed as the number of infected individuals per 100,000 inhabitants considering municipalities grouped in microregions and/or mesoregions as the unit of analysis.

Results: A total of 233,876 individuals were evaluated. Individuals were from 394 out of 417 municipalities of Bahia (94.5%). HTLV chemiluminescence/ELISA assay was found to be reactive for 3,138 individuals from whom 2,323 had WB results (1,978 positives, 62 negative and 282 indeterminate). Out of 1978 reactive samples, 1,813 (91.7%) were positive for HTLV-1, 58 (2.9%) for HTLV-2 and 107 (5.4%) were for both HTLV-1 and HTLV-2. The cumulative mean rate of HTLV-positive cases in Bahia was 14.4 per 100,000 inhabitants. Three microregions presented rates >20 HTLV-positive cases/100,000 inhabitants: Barreiras (24.83 cases per 100,000 inhabitants), Salvador (22.90 cases per 100,000 inhabitants), and Ilhéus-Itabuna (22.60 cases per 100,000 inhabitants).

Conclusion: HTLV infection is disseminated in the state of Bahia, with an overall moderate rate of infection. Further studies should be conducted to characterize the epidemiological and clinical profile of HTLV-infected individuals better and to propose effective prevention measures.

Keywords: Bahia; HTLV; clusters; epidemiology; spatial distribution.

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Figures

FIGURE 1
FIGURE 1
Illustration of the state of Bahia’s seven mesoregions and 32 microregions, grouped by IBGE to more accurately reflect economic and social similarities among this state’s municipalities.
FIGURE 2
FIGURE 2
Standards for reporting of diagnostic accuracy studies (STARD) flowchart illustration of study design. Boxes with dotted lines indicate samples excluded from the study.
FIGURE 3
FIGURE 3
Spatiotemporal distribution of HTLV positivity in the State of Bahia from 2004 to 2013, calculated using 3-year moving averages considering the state’s microregions as units of analysis.
FIGURE 4
FIGURE 4
Spatial distribution of overall HTLV, HTLV-1, HTLV-2, and HTLV-1/2 positivity in the State of Bahia from 2004 to 2013, considering microregions as the unit of analysis. The 12 microregions with the highest rates of HTLV positivity per 100,000 inhabitants are highlighted, in addition to the top five according to each respective HTLV type.
FIGURE 5
FIGURE 5
Distribution of HTLV-positive cases throughout the mesoregions of the State of Bahia, stratified according to sex and age (2004–2013).
FIGURE 6
FIGURE 6
Self-reported ethnicity/color of regional populations in the state of Bahia according to the Brazilian Institute of Statistics and Geography 2010 census. With respect to the representative map of individual identifying as “black,” bars represent the number of quilombola communities located in each mesoregion of the state (total number = 656).
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