Determinants of tuberculosis diagnosis and the role of counselling.

OBJECTIVE: To study patient determinants that may affect completion of the diagnostic process in tuberculosis control, highlighting the role of counselling. DESIGN: Cross-sectional study. SUBJECTS: TB patients. SETTING: Rhodes Chest Clinic, Nairobi, City Council. RESULTS: Ninety five percent of the suspects delivered three sputum samples but only 27% consented to a HIV test; several determinants for none consenting were mentioned. On average US$2.27 was spent for one clinic visit and U.S. $8.62 for following the entire diagnostic process. Cost factors included transport, loss of income and food. CONCLUSION: Individual pre-test counselling seems important for obtaining three sputum specimens. It takes time and for settings with a large number of suspects, alternative methods may be required. To obtain consensus for a HIV test in a TB clinic is complicated. Costs spent on transport and loss in income are important determinants and may contribute to poor patient adherence to the diagnostic process.

Urban-rural differences in questionnaire-derived markers of asthma in Kenyan school children.

Grade 4 Kenyan children attending 10 randomly selected public primary schools in Nairobi (urban) and the Muranga District (rural) were surveyed to establish the prevalence of symptom markers of asthma and to assess the impact of urbanization. A respiratory health and home environment questionnaire was administered at school to parents or guardians. The questionnaire response rates were 94.2% (568/ 603) for Nairobi and 89.6% (604/674) for Muranga. The prevalence rates for asthma, defined as "attacks of shortness of breath with wheeze", were 9.5% for urban and 3.0% for rural children (odds ratio (OR) urban versus rural: 3.42; 95% confidence interval (CI): -1.96-5.91). This urban-rural gradient persisted after adjusting for urban-rural differences in host factors (including duration of breastfeeding and family history of asthma and/or allergy), but was largely explained by urban-rural differences in environmental factors, including indoor animals, sharing a bedroom with a smoker, parental education, house ventilation and exposure to motor vehicle fumes en route to school (adjusted OR: 1.59; 95% CI: 0.70-3.55). Similar results were obtained for all other symptoms. These findings confirm the clinical impression that asthma is an important illness in Kenya and underline the need for the further study of environmental factors amenable to intervention, particularly in urban areas.

Home environment and asthma in Kenyan schoolchildren: a case-control study.

BACKGROUND: There is increasing evidence that environmental factors contribute to the development of asthma, so the relationship was studied between home environment factors and asthma among school children of varying socioeconomic backgrounds living in a developing country. METHODS: A case-control study was performed in participants of a prevalence survey which included 77 schoolchildren with asthma (defined by a history of wheeze, doctor diagnosis, or a decline in FEV1 of > or = 10% at five or 10 minutes after exercise) and 77 age and gender matched controls. Subjects were selected from 402 school children aged 9-11 years attending five primary schools in the city of Nairobi who participated in a prevalence survey of asthma. Visits were made to the homes of cases and controls and visual inspection of the home environment was made using a checklist. A questionnaire regarding supplemental salt intake, parental occupation, cooking fuels, and health of all children in the family was administered by an interviewer. RESULTS: In multivariate analysis the following factors were associated with asthma: damage caused by dampness in the child's sleeping area (adjusted odds ratio (OR) 4.9; 95% confidence interval (CI) 2.0 to 11.7), air pollution in the home (OR 2.5; 95% CI 2.0 to 6.4), presence of rugs or carpets in child's bedroom (OR 3.6; 95% CI 1.5 to 8.5). Children with asthma reported a supplemental mean daily salt intake of 817 mg compared with 483 mg in controls. CONCLUSIONS: Home environmental factors appear to be strongly associated with asthma in schoolchildren in a developing nation. These findings suggest a number of hypotheses for further studies.

The effect of human immunodeficiency virus type-1 on the infectiousness of tuberculosis.

SETTING: Developing country tertiary referral hospital plus catchment community. OBJECTIVE: To determine the infectiousness of culture-confirmed pulmonary tuberculosis in patients infected with Human Immunodeficiency Virus type-1 (HIV-1). DESIGN: Comparison of the incidence of tuberculosis and the prevalence of tuberculin skin test positivity among the household contacts of both HIV-1 positive and negative cases with pulmonary tuberculosis. RESULTS: Of 255 contacts of HIV-1 negative index cases, 2 were HIV-1 positive and of 102 contacts of HIV-1 positive index cases, 14 were HIV-1 positive (odds ratio (OR) = 20.0 95% Confidence Interval (CI) 4.4-193). 21 cases of tuberculosis were diagnosed among contacts, of whom 3 were HIV-1 positive. The overall unadjusted OR for tuberculosis among contacts of HIV-1 positive index cases was 1.6 (95% CI 0.6-4.3) compared to contacts of HIV-1 negative index cases. Amongst HIV-1 negative contacts alone the OR was 1.5 (95% CI 0.4-4.4). In this group the best predictors of tuberculosis among contacts were female sex of the index case (OR = 3.4 95% CI 1.1-12), sharing the same bed as the index case (OR = 2.6 95% CI 0.9-7.4), and contact's age less than 5 years (OR = 3.3 95% CI 1.1-9.5). HIV-1 positive contacts were more likely to develop tuberculosis than HIV-1 negative contacts (OR = 4.1 95% CI 0.7-17). Tuberculin skin test positivity rates were the same among the HIV-1 negative contacts of HIV-1 positive and negative index cases (OR = 1.1 CI 0.7-1.6). CONCLUSIONS: HIV-1 associated pulmonary tuberculosis is not more infectious than tuberculosis alone. The presence of HIV-1 in a community does not mandate a change in the management of contacts of patients with pulmonary tuberculosis.

PIP: Using data on tuberculosis (TB) index cases over age 15 years seen at the Infectious Diseases Hospital in Nairobi and the Ngaira Avenue Chest Clinic over September 1, 1989 and October 10, 1990, and their contacts, the authors determined the infectiousness of culture-confirmed pulmonary TB in patients infected with HIV-1. Comparing the incidence of TB and the prevalence of tuberculin skin test positivity among the household contacts of HIV-1 positive and negative cases with pulmonary TB found HIV-1-associated pulmonary TB to be no more infectious than TB alone. The presence of HIV-1 in a community therefore does not require a change in the management of contacts of patients with pulmonary TB.