Assessment of family and neighbors of an individual infected with Wuchereria bancrofti from a non-endemic area in the city of Maceió, Brazil

Abstract

This study received fi nancial support from PPSUS MS/CNPq/FAPEAL, PAHO/WHO. ABSTRACTThe family and neighbors of a patient infected with W. bancrofti microfi lariae were assessed aiming to evaluate the occurrence of cases of lymphatic fi lariasis in a non-endemic area in the city of Maceió, in the Brazilian state of Alagoas. The patient had previously lived in an endemic focus; however, he has been living in an area where the parasite has never been detected for the past ten years. Female ingurgitated Culex quinquefasciatus mosquitoes captured in the houses of the microfi laremic individual and of his neighbors in the non-endemic region were also examined by polymerase chain reaction (PCR) technique. The thick blood smear examination, blood membrane fi ltration, and rapid immunochromatography (antigen search) revealed no infected individuals in the family of the microfi laremic individual. All 334 neighbors undergoing the thick blood smear examination were negative for W. bancrofti microfi lariae. In 478 ingurgitated C. quinquefasciatus mosquitoes examined by PCR, no W. bancrofti DNA was detected. The microfi laremic individual had a microfi laremia considered very low according to WHO standards (4 microfi lariae/mL of blood). As the vectorial infection depends on microfi laremia, the patient's low parasite load did not determine the contamination of other individuals in the area. Our data have shown that the long-term residence of the microfi laremic individual in the non-endemic region was not suffi cient to start a new transmission focus of lymphatic fi lariasis in Maceió.

Secondary Mapping of Lymphatic Filariasis in Haiti-Definition of Transmission Foci in Low-Prevalence Settings

“…Different studies have reached independent conclusions regarding the possible risk. One study from Brazil found that one antigen-positive individual did not seem to pose a significant risk for transmission, as no one in the vicinity had become infected in the 10 years he lived in this non-endemic community [11] . However, this study was only observational and based on a single individual and therefore may not be generalizable to the overall population.…”