Trends of rubella incidence during a 5-year period of case based surveillance in Zimbabwe.

BACKGROUND: Rubella is a disease of public health significance owing to its adverse effects during pregnancy and on pregnancy outcomes. Women who contract rubella virus during pregnancy may experience complications such as foetal death or give birth to babies born with congenital rubella syndrome. Vaccination against rubella is the most effective and economical approach to control the disease, and to avoid the long term effects and high costs of care for children with congenital rubella syndrome as well as to prevent death from complications. Zimbabwe commenced rubella surveillance in 1999, despite lacking a rubella vaccine in the national Expanded Programme on Immunization, as per the World Health Organization recommendation to establish a surveillance system to estimate the disease burden before introduction of a rubella vaccine. The purpose of this analysis is to describe the disease trends and population demographics of rubella cases that were identified through the Zimbabwe national measles and rubella case-based surveillance system during a 5-year period between 2007 and 2011. METHODS: Data from the Zimbabwe National Measles Laboratory for the 5-year study period were analysed for age, sex, district of origin, seasonality, and rubella IgM serostatus. RESULTS: A total of 3428 serum samples from cases of suspected measles in all administrative districts of the country were received by the laboratory during this period. Cases included 51% males and 49% females. Of these, 2999 were tested for measles IgM of which 697 (23.2%) were positive. Of the 2302 measles IgM-negative samples, 865 (37.6%) were rubella IgM-positive. Ninety-eight percent of confirmed rubella cases were children younger than 15 years of age. Most infections occurred during the dry season. CONCLUSIONS: The national case-based surveillance revealed the disease burden and trends of rubella in Zimbabwe. These data add to the evidence for introducing rubella-containing vaccine into the national immunization programme.

Epidemiologic and genotypic characteristics of rotavirus strains detected in children less than 5 years of age with gastroenteritis treated at 3 pediatric hospitals in Zimbabwe during 2008-2011.

BACKGROUND: In anticipation of rotavirus vaccine introduction, the Zimbabwe Ministry of Health initiated rotavirus surveillance in 2008 to describe the rotavirus epidemiological trends and circulating genotypes among children <5 years of age. METHODS: Active hospital-based surveillance for diarrhea was conducted at 3 sentinel sites from January 2008 to December 2011. Children aged <5 years, who presented with acute gastroenteritis as a primary illness and who were admitted to a hospital ward or treated at the emergency unit, were enrolled in the surveillance program and had a stool specimen collected and tested for rotavirus by enzyme immunoassay. Genotyping of a sample of positive specimens was performed using reverse-transcription polymerase chain reaction. RESULTS: A total of 3728 faecal samples were collected and tested during the 4 year surveillance period and 1804 (48.5%) tested rotavirus positive. The highest prevalence of rotavirus diarrhea was found during the dry, cool season. Rotavirus positivity peaked in children 3-17 months of age with almost 80% of cases. Compared with rotavirus-negative cases, rotavirus-positive cases were more likely to be dehydrated (26% vs. 14%, P ≤ 0.001) and have vomiting (77% vs. 57%, P ≤ 0.001) and less likely to have fever (17% vs. 24%, P = 0.03). G9P[8] (43.3%), G1P[8] (11.8%), G2P[4] (8.7%), G2P[6] (8.7%) and G12P[6] (8.7%) were the most common genotypes detected. DISCUSSION: Rotavirus causes a significant disease burden among children <5 years of age in Zimbabwe. This active surveillance system can serve as a platform to monitor the impact of rotavirus vaccine on disease burden following vaccine introduction.