Thea Kølsen Fischer

Fischer 2002
Fischer, Thea Kølsen. 2002. Epidemiologic Studies of Rotavirus Infection in Guinea-Bissau, West Africa. Bandim Heatlh Project, Department of Epidemiology Research, Statens Serum Institut. Centre for International Health, University of Bergen.
The overall purpose of this thesis was to describe the epidemiology of natural rotavirus infections in Guinean children less than two years of age and to characterize the infecting rotavirus strains genotypically. The specific objectives were to:
  1. Estimate the incidence and seasonal variation of rotavirus infections
  2. Estimate the rotavirus mortality rates in sub­-Saharan Africa
  3. Estimate the protection that natural rotavirus infections confer against rotavirus re-infection and diarrhea
  4. Characterize the rotavirus strains with regard to VP7 (G) and VP4 (P) genotypes
The studies presented in this thesis show that rotavirus is an important contributor to the burden of diarrheal diseases among children less than two years of age in this West African community.

Although rotavirus infections were confined to four epidemic winter months, at least 74% of all children would experience such infections before their second birthday. Among all diarrheal pathogens detected, rotavirus was the single most important contributor to the diarrheal burden among 0 to 2 year old children in this community. As compared to other diarrheal pathogens, rotavirus infections were most frequently associated with diarrhea and represented the highest population attributable risk of all diarrheal pathogens identified (119).

Characterization of the infecting rotavirus strains revealed a wide range of different G and P genotype combinations. Moreover, there was a substantial shift in predominating genotypes. The globally most common types were underrepresented, whereas the worldwide less common P[6], G2 type constituted a considerable fraction (3l%) of all rotavirus strains identified among young children this setting. In-depth studies of incompletely typed rotavirus isolates revealed several uncommon G8 and G9 rotavirus strains as well as a high proportion of infections with more than one strain, suggesting the potential for reassortance of rotavirus gene segments in this population.

The estimated 52% and 70% protection conferred by natural rotavirus infection against re-infection and rotavirus diarrhea, respectively, supports current vaccine development strategies. Although statistically somewhat uncertain, the apparent reduction in protection from one season to the next underscores the need for follow-up for a minimum of two seasons subsequent to the evaluation of a vaccine candidate, in order to estimate any such loss of protection.

The present thesis corroborates the notion that rotavirus is an important cause of diarrheal disease in children less than two years of age, even in areas where the incidence of infections with other enteropathogens is high. Immunization with an effective vaccine, which mimics the protection conferred by natural infection, is probably the best approach to reduce rotavirus morbidity and mortality and is likely to have a substantial public health impact in developing countries.

See also: På sporet av nye vaksiner mot småbarnsdiaré (University of Bergen - in Norwegian)