Résumé
Relocation which is a well-known determinant of malaria in non-immune travelers to malarious areas; has also been found to be a risk factor for malaria among semi-immune persons who change locality within endemic regions. Further research evidence suggests that the higher transmission intensity at the travel location is an underlying factor which may indicate exposure to new variants of P falciparum for which specific immunity is lacking. This study was conducted to determine if recent change of locality increased the risk of malaria fever among semi-immune National Youth Service Corps members serving in a district in southern Nigeria.Method: Ninety six corps members who had just been posted to Ahoada-East LGA in southern Nigeria and 83 others that had been in service for six months; were followed up for malaria fever in a prospective cohort design over a 3 month period from September 2010 to December 2010. Active surveillance was used to obtain reports of fever among the cohort; followed by medical examination at designated local health facilities.Results: No significant differences in age and use of protection against malaria were found between the study groups. The incidence proportion of malaria for the recently relocated group (34) was significantly higher than that of the resident group (15.7). Recent change of locality was more associated with malaria fever (RR 2.19; 95 CI 1.243.88; AR 54.4).Conclusion: The recent change of locality within an endemic region; which serves as an indicator of exposure to new variants of P falciparum; for which specific immunity is lacking; is a significant risk factor for malaria fever. Protection against malaria is recommended for semi-immune individuals moving to new locations with significant risk of malaria transmission