Tuberculosis incidence in a cohort of individuals infected with human T-lymphotropic virus type 1 (HTLV-1) in Salvador, Brazil.

Maria Fernanda Rios Grassi,Normeide Pedreira Dos Santos,Afrânio Lineu Kritski,Maria Da Conceição Chagas Almeida,Monique Lírio,Eduardo Martins Netto,Bernardo Galvão-Castro,Juarez Dias,Noilson Lázaro,Leonardo Pereira Santana

doi:10.1186/s12879-016-1428-z

Abstract

BackgroundFew reports have investigated the association between human T-lymphotropic virus type 1 (HTLV-1) and tuberculosis (TB) in countries where both infections are endemic. This study estimates the incidence of TB in a cohort infected with HTLV-1, compared with non-infected individuals, over a ten-year period.MethodsRetrospective cohort study involving the cross-matching of records of individuals for whom a HTLV serology was performed at a referral center for HTLV (CHTLV) with a database of TB cases from Sinan—the Information System on Diseases of Compulsory Declaration between 2002 and 2012.ResultsFrom a cohort of 6,495 individuals, 1,711 were infected with HTLV-1. A total of 73 TB cases occurred during the study period: 33 HTLV-1-infected patients and 40 uninfected individuals. The incidence density for TB in the HTLV-1 infected group was 3.3 person-years per 1,000 individuals and 1.1 person-years per 1,000 individuals in the group HTLV-1 uninfected group. The relative risk of developing TB in the group of patients infected with HTLV-1 was 2.6 (CI 95 % 1.6–4.2) in comparison with HTLV-1 uninfected group. Compared to individuals with isolated TB, those in the HTLV-1 infected group who had TB were older (p = 0.005) and had lower education levels (p = 0.02). No differences were observed with respect to the clinical/radiological presentation, nor in the outcome of TB and prevalence of HIV infection, when comparing among the HTLV-1-infected and uninfected groups.ConclusionsPatients infected with HTLV-1 are more susceptible to TB. The epidemiological characteristics of HTLV-1/TB subjects and those infected with TB overlap.

Highlights

Few reports have investigated the association between human T-lymphotropic virus type 1 (HTLV-1) and tuberculosis (TB) in countries where both infections are endemic
Previous studies that have investigated the association between tuberculosis (TB) and HTLV-1, which were conducted in areas endemic for both infections, found a higher prevalence of HTLV-1 infection in patients diagnosed with tuberculosis (TB) in comparison to these patients’ relatives or control groups [15,16,17,18,19]
From January 2002 to April 2012, 6,620 individuals were tested for HTLV-1/2 at the center for HTLV (CHTLV), 125 of whom were excluded (Fig. 1)

Summary

Introduction

Few reports have investigated the association between human T-lymphotropic virus type 1 (HTLV-1) and tuberculosis (TB) in countries where both infections are endemic. Scattered reports have shown contradictory results with respect to the clinical outcomes of patients infected with both HTLV-1 and TB. While some of these reports described higher mortality in coinfected patients compared to those with isolated TB [22, 23], another found no differences regarding mortality or clinical characteristics [24]

Methods

Results

Conclusion