Background: Few and inconclusive results have been presented regarding the influence of human T-lymphotropic virus 1 (HTLV-1) infection on the risk of acquiring tuberculosis (TB).
Methods: In 1994-1997, we performed a prospective study on hospitalized adult patients with pulmonary TB in Guinea-Bissau and compared the clinical outcome in HIV-2 and HIV-negative patients. We determined the prevalence of HTLV-1 in all patients screened and diagnosed with TB in that study and compared the infection rate with a serosurvey of HTLV-1 in a population sample from a community-based study conducted at the same time and in the same city.
Results: In the TB group, a total of 32 (11.4%) of 280 patients were positive for HTLV-1. This was significantly higher compared with the population-based group in which 74 (3.5%) of 2117 were HTLV-1 positive [crude odds ratio (OR) = 3.6; 95% confidence interval (CI) 2.2 to 5.6, P < 0.001]. However, in a logistic regression analysis controlling for age, gender, and HIV result, the difference was no longer significant (OR = 1.61; 95% CI 0.95 to 2.70, P = 0.074). In HIV-negative patients, no association was found between HTLV-1 and TB (OR = 1.18; 95% CI 0.48 to 2.89, P = 0.71), whereas a significant association was found in HIV-positive patients (OR = 2.41; 95% CI 1.26 to 4.61, P = 0.008).
Conclusions: The immunosuppressive effect of HTLV-1 alone was not enough to increase the risk of TB in a highly endemic country, but HTLV-1 increased the risk of TB among HIV-infected individuals.
From the *Division of Infection Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden; †National Public Health Laboratory, Bissau, Guinea-Bissau; ‡Raoul Follereau Hospital, Bissau, Guinea-Bissau; §Projecto de Saude de Bandim, Indepth Network, Bissau, Guinea-Bissau; and ‖National Institute for Infectious Disease Control, Stockholm, Sweden.
Received for publication March 5, 2008; accepted May 6, 2008.
Supported by the Swedish International Development Cooperation Agency (SIDA), Department of Research Cooperation (SAREC), the Danish Medical Research Council, the Danish Research Academy, and the Science and Technology for Development Programme of the European Community.
The data have not been presented at any meeting.
Correspondence to: Hans Norrgren, MD, PhD, Department of Infectious Diseases, University Hospital of Lund, S-221 85 Lund, Sweden (e-mail: firstname.lastname@example.org).