Impact of conjugate Haemophilus influenzae type b (Hib) vaccine introduction in South Africa.

OBJECTIVE: To analyse trends in reported invasive Haemophilus influenzae disease in South Africa within the first five years of introduction of conjugate Haemophilus influenzae type b (Hib) vaccine in the routine child immunization schedule. METHODS: We used national laboratory-based surveillance data to identify cases of invasive H. influenzae disease between July 1999 and June 2004, and submitted isolates for serotyping and antimicrobial susceptibility testing. FINDINGS: The absolute number of Hib cases (reported to the national surveillance system) among children below one year of age decreased by 65%, from 55 cases in 1999-2000 to 19 cases in 2003-04. Enhanced surveillance initiated in 2003, identified human immunodeficiency virus (HIV)-infection and incomplete vaccination as contributing factors for Hib transmission. The total number of laboratory-confirmed cases of H. influenzae remained unchanged because non-type b disease was being increasingly reported to the surveillance system concomitant with system enhancements. Children with non-typable disease were more likely to be HIV-positive (32 of 34, 94%) than children with Hib disease (10 of 14, 71%), P = 0.051. Recent Hib isolates were more likely to be multidrug resistant (2% in 1999-2000 versus 19% in 2003-04, P = 0.001). CONCLUSION: Data from a newly established national laboratory-based surveillance system showed a decrease in Hib disease burden among South African children following conjugate vaccine introduction and identified cases of non-typable disease associated with HIV infection.

Exposures to Legionella pneumophila and Chlamydia pneumoniae in South African Mine Workers.

Exposures of South African mine workers to Legionella pneumophila and Chlamydia pneumoniae were studied over a period of six months. Seroprevalence data were compared with data from a group of factory workers. Antibodies to L. pneumophila serogroups 1-4 were demonstrated in 36% of the mine workers and 10% of the factory workers (p < 0.0001). Seroconversion occurred in 18% of the mine workers during the study period. Antibodies to C. pneumoniae were present in 66% of the mine workers and 22% of the factory workers (p < 0.0001). Seroconversion was demonstrated in 17% of the mine workers during the six months of follow-up. A significant association between the presence of respiratory symptoms and seroconversion was demonstrated (p < 0.025). The data suggest that mine workers are at increased risk for infections with L. pneumophila and C. pneumoniae. Legionella pneumophila; Chlamydia pneumoniae; mine workers; factory workers; risk factors; seroprevalence; seroconversion