Prevalence and transmission pattern of Plasmodium falciparum infection in Osogbo metropolis, southwest, Nigeria.

Plasmodium falciparum malaria is an endemic disease especially in tropical areas with heavy rainfall that spread round the year. We therefore sought to investigate the prevalence pattern and clinical presentation of falciparum malaria in Oso degrees c were assessed and screened for plasmodium falciparum infection by clinical assessment and microscopy using both thick and thin blood smears over a period of 12 months- August 2004 and July 2005. The prevalence of Plasmodium falciparum infection was found to be 52.8% with 341/646 of the patients been positive for Plasmodium falciparum parasite based on microscopy. Three hundred and five (47.2%) were aparasitaemic of which 162 (25.1%) had bronchopneumonia, 99 (15.3%) had upper respiratory tract infection, 32 (5.0%) had gastroenteritis and 12 (1.9%) had Otitis media. Between August and November 2004, 250 patients were screened and 160 (57.6%) of these patients were positive, while 180 patients were screened between December 2004 and March 2005 and 51 (28.3%) were positive. Between April 2005 and July 2005, 216 patients were screened and 130 (60.2%) of the patients were positive. When compared, the differences in the percentage of patients with positive microscopy in December to March with April to July and August to November were found to be significant (P < 0.0001), whereas the percentage difference in patients with positive microscopy in August to November and April to July was not significant (P = 0.442). The result of this study clearly shows that there are two distinct peaks of malaria transmission pattern in consonance with the rainfall pattern in the area.