Amblyomma aureolatum Genetic Diversity and Population Dynamics Are Not Related to Spotted Fever Epidemiological Scenarios in Brazil

Abstract

Regional differences in tick-borne disease epidemiology may be related to biological variations between vector populations. <i>Amblyomma aureolatum</i> (Ixodida: Ixodidae), a neotropical tick, is known from several regions in Brazil. However, only in the metropolitan area of São Paulo (SP) state are there studies that establish its role as a vector of a pathogenic rickettsia (<i>Rickettsia rickettsii</i>). The aim of the study was to analyze the genetic diversity, population dynamics, and rickettsia infection in <i>A. aureolatum</i> populations from different spotted fever scenarios in Brazil. Samples were subjected to DNA extraction, amplification and sequencing of 12S rDNA, cytochrome oxidase subunit II and D-loop mitochondrial markers for tick population analyses, and <i>glt</i>A, <i>htr</i>A, <i>omp</i>A, and <i>omp</i>B genes for rickettsia researches. Of the 7-17 tick haplotypes identified, 5-13 were exclusive to each population and 2-12 for each epidemiological scenario, as well as three haplotypes shared by all populations. <i>Amblyomma aureolatum</i> populations are expanding, and do not appear to be genetically structured vis-a-vis the different epidemiological scenarios studied. <i>Rickettsia bellii</i> (in SP) and <i>Rickettsia felis</i> (in Santa Catarina) were identified as infecting <i>A. aureolatum</i>. No relationship between tick haplotypes and rickettsia types were observed.