A focus of plasmodium malariae in Trinidad, West Indies

ABSTRACT

This report describes a focus of Plasmodium malariae on the island of Trinidad, some 30 years after a successful eradication programme. A total of 22 cases of P. malariae was detected using blood smears in the Nariva-Mayaro area of Trinidad from August 1994 to September 1995, with 77.3 percent of the cases being males and 22.7 percent being females. Seven of the 22 cases were individuals < 25 years of age suggesting that malaria transmission was renewed by the anopheline vectors Anopheles bellator and Anopheles homunculus. None of the three thousand mosquitoes tested by ELISA for cirumsporozoite protein of P. malariae proved positive. Blood samples tested using polymerase chain reaction (PCR) proved negative for P. malariae, while indirect fluorescent antibody (IFA) serology proved more sensitive. For example, from 325 IFA samples tested, 42 (12.9 percent) had titres of 1256 for higher. These results suggest that malaria transmission levels were higher than those reported by blood smears and PCR. The surveillance measures adopted to understand the epidemiology of this outbreak of P. malariae from Trinidad are described. The need of maintain malaria surveillance in all countries where P. malariae parasites existed prior to eradication is emphasized.(AU)