Aspectos epidemiológicos da raiva em áreas de fogo no Estado do Maranhão

Abstract

Rabies is an acute viral disease that affects mammals, caused by an RNA virus belonging to the family Rhabdoviridae and the genus Lyssavirus. The disease is transmitted through the bite or scratch of an infected animal. Rabies was one of the first infectious diseases to be scientifically studied, with a detailed description of symptoms and clinical course provided by Greek and Roman scholars in the early centuries AD. The global incidence of rabies varies in different regions of the world. It is estimated that the disease causes about 60,000 deaths worldwide each year, with higher prevalence in areas lacking effective control measures. Most

cases occur in developing countries where animal vaccination and proper post- exposure prophylaxis are less accessible. The rabies virus has several variants that

are specific to each reservoir, and in Brazil, five of these variants have been identified. This study aims to better understand the epidemiological aspects of rabies virus variants circulating in the state of Maranhão through immunological and molecular analyses, as well as their reservoirs and distribution in biomes. To achieve this, 62 biological samples sent to reference laboratories in the state between 2015 and 2022 were analyzed using fluorescent antibody test (FAT) and polymerase chain reaction (PCR) techniques. The primers 504 (sense) and 304 (reverse) were used for the N gene in PCR reactions, amplifying 240 bp, and positive samples were subjected to genetic sequencing to identify the antigenic variant. Of all the samples, 74% tested positive in DIF and 63% tested positive in PCR. Among the samples negative in DIF, 19% were detectable for the rabies virus in PCR. Of all the samples that tested positive in both tests, only 28% were successfully sequenced, revealing antigenic variants of Desmodus rotundus and Cerdocyon thous. It was observed that these variants circulate in both the Amazon and Cerrado biomes, with the bat variant being more prevalent in the Amazon biome, while the wild canid variant was more prevalent in the Cerrado. Therefore, the wild canid variant raises an alert for epidemiological surveillance, as it is already being transmitted to domestic dogs and humans in the state of Maranhão.