Impact of tuberculosis exposure at home on mortality in children under 5 years of age in Guinea-Bissau.

OBJECTIVE: To assess mortality related to exposure to tuberculosis (TB) at home among children in urban areas of Guinea-Bissau. METHODS: In four suburban areas included in the demographic surveillance system of the Bandim Health Project in Bissau, the mortality of children aged <5 years living with an adult with TB was compared with the mortality of children in the general population. RESULTS: Children <5 years of age exposed to an adult with intrathoracic TB had 66% higher mortality than unexposed children (HR 1.66, 95% CI 1.2 to 2.3). The risk was higher for children living in the same family as a TB case (HR 2.15, 95% CI 1.3 to 3.7) than for children living in the same house but not belonging to the same family as the TB case (HR 1.51, 95% CI 1.0 to 2.2). For children whose mother had TB, mortality was increased eightfold (HR 7.82, 95% CI 2.1 to 30). The risk of death was particularly increased from 6 months following exposure (HR 2.16, 95% CI 1.5 to 3.2) and the highest rate of excess mortality was found in children aged 3­4 years. Excess mortality was highest among children with close contact with an adult with sputum-positive pulmonary TB (HR 1.90, 95% CI 1.1 to 3.2), but contact with a sputum-negative case was also associated with increased mortality (HR 1.55, 95% CI 1.0 to 2.3). Adjusting for potential confounding factors did not change these results. The mortality among children living in the same houses 3 years earlier was not increased (HR 0.90, 95% CI 0.6 to 1.3). CONCLUSION: Intimate family contact with a TB case represents a significant risk factor for child mortality in a low-income country.

Risk factors for positive tuberculin skin test in Guinea-Bissau.

BACKGROUND: The tuberculin skin test is used for tracing of tuberculosis transmission and identifying individuals in need of prophylactic treatment. METHODS: Using a case-control study design, we recruited 220 smear-positive tuberculosis cases and 223 randomly selected healthy community controls in Bissau, Guinea-Bissau, during 1999-2000. Tuberculin skin tests were performed on family members of cases and controls (n = 1059 and n = 921, respectively). Induration of 10 mm or greater was considered positive. Risk factors were calculated for children (<15 years) and adults separately in multivariate logistic regression analysis. RESULTS: The prevalence of positive tuberculin skin test was 41% in case-contacts compared with 22% in control-contacts, resulting in a prevalence ratio of 1.48 (95% confidence interval = 1.37-1.60). Positive skin tests among case-contacts increased with age for children, as well as with proximity to a case during the night, for both children and adults. A Bacille Calmette Guerin scar increased the likelihood of having a positive tuberculin skin test for adults in case households, but not in other categories of contacts. Among control-contacts the prevalence of positive skin test was associated with older age in children, history of tuberculosis in the family, and a positive tuberculin skin test of the control person. CONCLUSIONS: Risk factors for a positive tuberculin skin test among case- and control-contacts are closely related to tuberculosis exposure. Having a BCG scar did not increase the risk of positive skin test in unexposed individuals. Tuberculin skin testing remains a useful tool for diagnosing tuberculosis infection.

Tuberculosis in Bissau: incidence and risk factors in an urban community in sub-Saharan Africa.

BACKGROUND: Despite the long history of tuberculosis (TB) research, population-based studies from developing countries are rare. METHODS: In a prospective community study in Bissau, the capital of Guinea-Bissau, we assessed the impact of demographic, socioeconomic and cultural risk factors on active TB. A surveillance system in four districts of the capital identified 247 adult (>or=15 years) cases of intrathoracic TB between May 1996 and June 1998. Risk factors were evaluated comparing cases with the 25,189 adults living in the area in May 1997. RESULTS: The incidence of intrathoracic TB in the adult population was 471 per 100 000 person-years. Significant risk factors in a multivariate analysis were increasing age (P < 0.0001), male sex (odds ratio [OR] = 2.58, 95% CI: 1.85, 3.60), ethnic group other than the largest group (Pepel) (OR = 1.64, 95% CI: 1.20, 2.22), adult crowding (OR = 1.68, 95% CI: 1.18, 2.39 for >2 adults in household), and poor quality of housing (OR = 1.66, 95% CI: 1.24, 2.22). Household type was important; adults living alone or with adults of their own sex only, had a higher risk of developing TB than households with husband and wife present, the adjusted OR being 1.76 (95% CI: 1.11, 2.78) for male households and 3.80 (95% CI: 1.69, 8.56) for female households. In a multivariate analysis excluding household type, child crowding was a protective factor, the OR being 0.68 (95% CI: 0.51, 0.90) for households with >2 children per household. CONCLUSIONS: Bissau has a very high incidence of intrathoracic TB. Human immunodeficiency virus (HIV), increasing age, male sex, ethnicity, adult crowding, family structure, and poor housing conditions were independent risk factors for TB. Apart from HIV prevention, TB control programmes need to emphasize risk factors such as socioeconomic inequality, ethnic differences, crowding, and gender.

Community study of the relative impact of HIV-1 and HIV-2 on intrathoracic tuberculosis.

BACKGROUND: HIV-1 infection is associated with an increased incidence of and mortality from tuberculosis. Few community studies have examined the effect of HIV-2 on tuberculosis. METHODS: We investigated the association between HIV-1, HIV-2 and active tuberculosis in four districts (population 42 709) in Bissau, capital of Guinea-Bissau, with the highest known seroprevalence of HIV-2 infection in the world. From May 1996 to June 1998, tuberculosis surveillance and active case finding among contacts was conducted. Patients were HIV-tested, given specific tuberculosis treatment for 8 months and followed regarding mortality. Simultaneously, an HIV sero-survey was performed in a random sample of 1748 permanent residents. RESULTS: During a 25-month period, 366 tuberculosis cases were identified. After excluding cases among visitors to the area, and adjusting for age, the incidence of tuberculosis was 18.3 times higher (95% CI 12.9-26.0) among HIV-1-positive individuals, 13.7 times higher (9.0-20.7) among dually infected (HIV-1 and HIV-2), and 3.0 times higher (2.1-4.3) among HIV-2-infected compared with HIV-negative individuals. HIV-1 and dually infected tuberculosis patients had a higher mortality rate than HIV-negative tuberculosis patients [mortality ratio (MR) 2.68; CI 1.11-6.48 and 2.89; CI 1.13-7.39, respectively]. The survival of HIV-2-positive tuberculosis patients was similar to that of HIV-negative tuberculosis patients (MR 1.19; CI 0.46-3.06). CONCLUSION: The presence of HIV-2 infection increases the incidence of tuberculosis compared with that in non-HIV-infected individuals, but does not affect tuberculosis-related mortality in the short term. In contrast, the presence of HIV-1 infection, alone or with HIV-2, has a several-fold greater impact on both the incidence of and mortality from tuberculosis.