A household survey of dysentery in Burundi: implications for the current pandemic in sub-Saharan Africa

To characterize the epidemiology of dysentery (defined as bloody diarrhoea) in Burundi, we reviewed national surveillance data and conducted a household cluster survey including two case--control studies: one at the household, the other at the individual level. We estimated that community incidences for dysentery (per 1000 residents) in Kibuye Sector were 15.3 and 27.3, and that dysentery accounted for 6% and 12% of all deaths, in 1991 and 1992, respectively. Factors associated (P < or = 0.05) with contracting dysentery were being female, using a cloth rag after defecation, a history of recent weight loss, and not washing hands before preparing food. The attributable risk, at the household level, of not washing hands before preparing food was 30%. Secondary household transmission accounted for at most 11% of dysentery cases. This study suggests that Shigella dysenteriae type 1 may be one of the leading causes of preventable mortality in Burundi and other African countries where effective antimicrobial agents are no longer affordable. Since hands were the most important mode of transmission of S. dysenteriae in this study, community-based interventions aimed at increasing hand washing with soap and water, particularly after defecation and before food preparation, may be effective for controlling dysentery epidemics caused by S. dysenteriae type 1 in Africa.

A 'post-honeymoon period' measles outbreak in Muyinga sector, Burundi

In Muyinga sector, Burundi, an area with good vaccination levels against measles and recent low incidence of measles, a major outbreak of measles in 1988 raised questions about the efficacy of the immunization programme. To help answer these questions, we 1) reviewed programme data on doses of measles vaccine administered, vaccine coverage, and measles incidence, and 2) conducted a census of the affected area to examine vaccine efficacy and measles mortality. We found that between 1980 and 1988 in Burundi, 1) measles vaccine coverage by age 1 had increased from 0% to 55%, 2) the incidence of reported measles cases declined from 12.1/1000 to 6.2/1000, 3) reported measles mortality dropped from 0.18/1000 to 0.08/1000, and 4) the interepidemic period had increased from 25 to 35 months. In the census, the best estimate of measles vaccine efficacy administered at 9 months of age was 73%. Measles increased the risk of death by 2.5-fold with the effect limited to the first month after measles. This outbreak demonstrated the 'post-honeymoon period' epidemic predicted by mathematical models in which outbreaks occur among accumulated susceptibles in a partially immunized population. Understanding this phenomenon is important in providing a basis for improved strategies of measles control. Such outbreaks present new challenges to newly maturing immunization programmes in improving skills in surveillance, outbreak investigation, and public relations.