Relação entre os vetores da febre maculosa brasileira Amblyomma sculptum e Amblyomma dubitatum e riquetsias com o ambiente: avaliação do risco de picada humana em áreas antropizadas

Abstract

Brazilian spotted fever (BSF), a disease with high lethality caused by the bacterium Rickettsia rickettsii, has two recognized ecological scenarios in Brazil. Understanding these scenarios is very relevant, as they are the main and even the only indication that a febrile illness may be BSF. In addition, due to the hyperacute course of the disease, treatment must be started before laboratory confirmation of the disease. The scenario responsible for most cases is found in the Southeast and is characterized by the presence of large populations of capybaras and intense environmental infestation by ticks. However, the presence of capybaras and ticks does not automatically indicate transmission of R. rickettsii to humans and many doubts surround the epidemiology of the disease. An important but still ill-known aspect of epidemiology is the participation of two species of tick and the influence of other species of Rickettsia on the transmission of the BSF agent to humans. Invariably the tick Amblyomma sculptum is considered the vector, particularly in the nymphal stage. However, in most situations, the tick that transmits the pathogen is not recovered. On the other hand, in areas with capybaras, the environmental infestation occurs both by A. sculptum and Amblyomma dubitatum, and experimentally both are capable of transmitting R. rickettsii. Understanding the relationship between the two species of ticks with rickettsiae and the risks to which people are exposed is of great importance so that preventive measures can be taken. In this work, several aspects of BSF eco-epidemiology were investigated at ten locations with a predisposition for rickettsial disease and distributed throughout the city of Uberlândia, Minas Gerais, Brazil.