Epidemiological Description Of Infection With Agents Of The Rickettsia Genus In Rodents, Ectoparasites And Humans In The Northern Coast Of Antioquia, Colombia

Background: Rickettsia is a worldwide usually rodent-carried tick, flea or lice-borne bacteria. In Colombia, few reports have beed performed, first in the mids thirties causing an outbreak in the population of Tobia Cundinamarca, and from the years 2006 to 2008 in the Northern region of Colombia known as Urabá. Our main goal was to perform an epidemiological description of the infection in the endemic mentioned area in Colombia. Methods: Samples were obtained from the municipalities of Apartadó, Turbo y Necoclí, where 335 rondents were captured and parasites were collected from 33 of them. 220 double-blood human samples were also taken (acute and convalescent phase) from patients with febrile syndroms negative to malaria by direct blood-smear test. Indirect Immunofluorescence (IFI), was used to detect rickettsial infection in humans and rodents. Additionally, PCR was performed in liver-DNA from rodents searching for specific genetic sequences of Rickettsia genus (Citrate Synthase gene, gltA) and pathogenic Rickettsias (OmpB gene). Results: We obtained 23 rodent DNA samples positive to gltA but only 6 of them, positive for the OmpB gene, resulting on a 6.8% DNA frequency of infection to Rickettsias by PCR. Some PCR products for the gltA gene, were sequenced and showed 98% similarity with the Rickettsia Prowazekii species, but the phylogenetic analysis suggests that these sequences form a separated cluster indicating that these Rickettsias could represent a new specie or sub specie. 89 of the 220 human sera were tested by IFI and 11 came up positive in dilution 1:64 (10 of the samples were positive in the convalescence period M2, and one in the acute phase, M1). Most of the ectoparasites collected were identified as hard ticks (Amblyomma sp, Ixodidae family,) soft ticks (Ornithodoros Alectorobius puertoricensis, Argasidae family) and fleas (Xenospsilla sp genus). These samples still remain to be tested for rickettsial infection using both gltA and OmpB. Conclusion: This is the firs of a serie of studies that will allow us to characterize ecologically this endemic site and contribute to recomend the measures to prevent future human cases in this important risk area. Abstracts for SupplementInternational Journal of Infectious DiseasesVol. 14Preview Full-Text PDF Open Archive