SEARCH FOR RICKETTSIA BACTERIA IN MOSQUITO SAMPLES FROM ARGENTINA
Rickettsias are a obligate genus of intracellular Gram-negative bacteria that cause various diseases worldwide and are primarily transmitted by vectors such as ticks, fleas, lice, and other mites. Rickettsioses are a group of emerging and re-emerging zoonotic diseases globally, characterized by a range of clinical manifestations from mild to fatal.Bacteria of this genus can cause a wide variety of diseases in humans, including those in the spotted fever group and the typhus group. Some rickettsias, such as R. prowazekii and R. rickettsii, can cause severe and highly lethal diseases.Various studies worldwide have detected the presence of Rickettsia in different arthropods, particularly in ticks. However, few studies have been conducted on mosquito populations. In Argentina, there are currently no such studies, so it is unknown whether rickettsias circulate in mosquitoes. Therefore, this study aims to detect rickettsias in mosquito samples using molecular techniques. The study was conducted at the National Institute of Human Viral Diseases "Dr. Julio I. Maiztegui" (INEVH-ANLIS) in Pergamino city.Mosquito specimens were collected in the northeast of the province of Corrientes as part of entomovirological surveillance for yellow fever in 2019. After taxonomic identification, pools were formed according to species and collection site. These pools were macerated with a bovine albumin solution, genomic DNA was extracted using the TRIzol protocol, and a final-end PCR (Polymerase Chain Reaction) was performed to amplify the gltA gene to detect Rickettsia genus bacteria. If a positive result was obtained, a Nested PCR (Nested Polymerase Chain Reaction) was carried out to amplify the ompA gene and a PCR to amplify the ompB gene, which allows differentiation at the species level within the Rickettsia genus.To identify the etiological agent, fragment purification and nucleotide sequencing were performed using the Sanger method on the appropriately sized bands.A total of 787 mosquito specimens distributed across 85 pools were analyzed. Rickettsia tillamookensis was detected in one pool of Coquillettidia nigricans species, collected in the locality of Tabay, Corrientes, Argentina.This study identifies the presence of Rickettsia tillamookensis in mosquitoes from the province of Corrientes and highlights the importance of beginning to analyze rickettsias in this group. Furthermore, this finding underscores the need to start studying the role of mosquitoes in the transmission of rickettsias.