Situação epidemiológica da filariose linfática bancroftiana no município de Maceió, estado de Alagoas

Abstract

Bancroftian lymphatic filariasis is a neglected parasitic illness, known popularly as elephantiasis, because it is one of its chronic clinical manifestations. It is an anthroponotic disease caused by a nematode helminth of the species Wuchereria bancrofti (Cobbold, 1877) (Spirurida: Onchocercidae). Bancroftian filariasis occurs in 83 countries localized in tropical and subtropical regions and is considered by the World Health Organization as the second leading cause, worldwide, of work disability. With the objective to ascertain the current distribution of lymphatic filariasis in Maceio, based upon previous studies, hemoscopic and entomological surveys were conducted in the city. The hemoscopic surveys were performed using a thick blood smear (TBS) in a random sample of 20,025 students of night schools, enrolled in the 143 public schools that cover the 50 districts of the city, a sample of 1418 employees of the same public night schools and of 546 soldiers of the Brazilian Army s 59th Motorized Infantry Battalion. Also evaluated by TBS was the family of the sole microfilaremic person found, composed of four individuals and 239 families of current and former neighbors of this patient, with a total of 943 individuals. The entomological survey, for which the methodology of xenomonitoring was adopted, was conducted in an area of the city where they found the microfilaremic person diagnosed during the study. For this, in the residences of microfilaraemic person and his neighbors, 478 engorged female mosquitos of the species Culex quinquefasciatus (Say, 1823) (Diptera: Culicidae) were caught and examined by PCR. No microfilaremia was diagnosed in the hemoscopic surveys conducted among the night school students and soldiers of the Army. Among the employees of the schools just an individual microfilaremic person was diagnosed living in the Benedito Bentes district, locality considered free of lymphatic filariasis, however he was a past resident of the Jacintinho district which is endemic for the disease. The sole microfilaremic found in the study had microfilaremia considered very low (4 mf/mL of blood). The hemoscopic survey conducted among the current neighbors (Benedito Bentes 336 individuals) and the previous neighbors in the endemic area (Jacintinho 607 individuals) did not detect microfilaremia. The entomologic survey revealed that there were no examples of mosquitos with W. bancrofti DNA in the home of the person or the surrounding region. It was demonstrated that the sole microfilaremic person, that lived in a non-endemic area for 10 years, could not be epidemiologically important as a source of infection (reservoir) possibly due to his low level of microfilaremia. These results, associated with recently released data that report a significant reduction of the disease in endemic areas of the city, suggests that there is no transmission of Bancroftian lymphatic filariasis in the city of Maceio.