Differences in tuberculosis incidence rates in township and in rural populations in Ntcheu District, Malawi

There has been a large upsurge of tuberculosis (TB) in many countries in su b-Saharan Africa, mainly as a result of the co-existing human immunodeficie ncy virus (HIV) epidemic. Malawi has had a well-run National TB Control Pro gramme (NTP) with good registration and recording of cases. For some years the NTP has had the impression that TB in the country is concentrated aroun d townships and is less prevalent in the rural areas. This impression was i nvestigated in a rural district (Ntcheu District) in Malawi. Data on new TB cases were collected from the district TB register for the years 1992-96 a nd average annual TB incidence rates per 100 000 for semi-urban and rural p opulations were calculated for this period. There was a significantly highe r incidence of TB, particularly amongst cases with smear-negative pulmonary TB and extrapulmonary TB, in the semi-urban population compared with the r ural population. Possible explanations could be higher HIV seroprevalence r ates in semi-urban areas compared with rural areas, under-diagnosis at heal th centres or poor access to medical facilities for rural people.