Measles: Factors influencing the morbidity and mortality in the under five year old children at the University Teaching Hospital, Lusaka

Abstract

Reported here are factors that influence the morbidity and mortality in hospitalised Zambian children with measles. A prospective study on 2174 children was undertaken to analyse the clinical presentations and complications in children hospitalised for measles between 1993 to 1996 and between 1998 and 1999 at the University Teaching Hospital (UTH), Lusaka, Zambia. The age distribution was from 1 month to 15 years. Hospitalisation for measles infection was most common in children below the age of one year (36.9%,803/2174). Diarrhoea, pneumonia and oral candidiasis were the most common complications of measles (67.6%, 53.3%* and 38.6% respectively). The overall measles case fatality rate (CFR) was 13.7%, and was higher in children less than 3 years of age (16.6%). The CFR was significantly associated with otitis media (45.0%), oral candidiasis (20.1%), pneumonia (18.6%), and diarrhoea (15.4%). When the above were stratified with HIV-1 sero-status, the CFR was significantly higher in the HIV-1 sero-positive than in the sero-negative (27.3% Vs 7.7%, p<0.001). The CFR decreased by age in the HIV-1 sero-negative children. On the contrary, CFR was also high in older children in sero-positive children. In HIV sero-positive group more children had been previously vaccinated, and the CFR was high even in vaccinated children, suggesting low vaccine efficacy in HIV-1 sero-positive children. Complications such as pneumonia, oral candidiasis and otitis media were more common in HIV sero-positive children, but diarrhoea was equally seen in both HIV sero-positive and sero-negative groups. Molecular analysis of the currently circulating measles virus showed that they belonged to group D2, and this was consistently demonstrated across a period of 7 years. Only silent minor mutations were detected, documenting the point that measles virus is a very stable virus antigenically. Therefore, A the current measles vaccine available in Zambia, the Schwarz vaccine is still immunogenic in inducing protective antibodies against the wild measles virus circulating in Zambia.The study demonstrates that children with severe measles admitted to UTH had a high CFR, and that measles infection was more severe in HIV-1 sero-positive children. Measles is increasingly becoming a major problem in young infants below the immunisation age of 9 months. Therefore, new strategies should be developed to protect young infants below 9 months. Finally, it is recommended that there is urgent need to develop new immunisation strategies to protect young infants from measles. These could take the form of immunisation of adolescent girls as they enter the reproductive age group and a two-dose measles schedule in infants. Prevention of mother to child transmission of HIV could subsequently prevent severe measles infection in HIV positive children. More importantly, there is urgent to increase routine measles immunisation coverage to over 95%. Life threatening complications like hypoglycaemia and dehydration should be identified and treated promptly and adequately in children especially those with oral candidiasis.