Epidemiology of Rickettsia spp. in Atlantic rainforest areas of island and seashore mainland, southern Brazil

One health approach to Rickettsia spp.: Brazilian indigenous individuals, their dogs and ticks, and healthcare professionals

Although Indigenous populations have historically overlapped the occurrence of vector-borne pathogens, no One Health approach study has investigated Rickettsia spp. in indigenous communities worldwide. Accordingly, the aim of this study was to investigate anti-Rickettsia spp. antibodies in indigenous individuals, their dogs and healthcare professionals, and Rickettsia spp. infection in ticks from ten indigenous communities of southern and southeastern Brazil. In overall, 66/771 (8.6 %) indigenous individuals, 9/99 (9.1 %) healthcare professionals and 116/386 (30.1 %) dogs were seropositive for at least one out four Rickettsia species tested by immunofluorescence assay (IFA). Out of 603 ticks collected from dogs in indigenous communities, 9/190 (4.7 %) tested positive to fragment of Rickettsia gltA gene by real-time PCR. The homologous antigenic reactions in dogs were significantly more frequent for R. bellii when compared to R. parkeri and R. amblyommatis and may be associated with the high diversity of hard and soft ticks in Americas, and R. bellii capacity of inhibiting another pathogenic rickettsia. Tick bite history increased the seropositivity (odds ratio = 9.29; p = 0.019) in healthcare professionals. This difference may be consequence of higher capacity to recognize tick bites by healthcare professionals, which highlighted the necessity of health care education for indigenous individuals for prevention and early recognition of tick-borne diseases in indigenous communities. In addition, the One Health approach herein has provided a holistic understanding of Rickettsia spp. infection in such communities and correspondent healthcare personal.

One Health Approach to Brazilian Spotted Fever: Capybaras, Horses, and Rural Areas as Predictors for Human Disease

(1) Background: Brazilian spotted fever (BSF) is a tick-borne disease that has occurred in several Brazilian regions, caused by Rickettsia spp. bacteria and mainly transmitted by Amblyomma ticks. Despite the high BSF lethality in several Brazilian endemic areas, predictors and associated risk factors remain to be fully established. Accordingly, the retrospective study herein aimed to assess BSF cases and associated factors in an endemic area of western São Paulo state. (2) Methods: Notified cases identified by the System for Epidemiological Surveillance of São Paulo (CVE), from January 2007 to December 2021, were gathered and analyzed by Logistic Multivariate Regression (LMR) to assess potential risk factors for BSF. (3) Results: Overall, 74/1121 (6.6%; 95% CI: 5.29-8.21) individuals were considered positive for BSF. Univariate analysis showed previous contact with capybaras (OR: 1.89; 95% CI: 1.0-3.55; p < 0.001) and raising horses (OR = 1.4; 95% CI: 0.66-2.67; p = 0.45), while LMR revealed living in rural areas (OR = 2.0; 95% CI: 1.02-3.73; p = 0.037) as an associated risk factor for BSF. (4) Conclusions: The results herein show that the geographically studied area still shows high occurrence of BSF, mostly for individuals living or visiting areas overlapping free-ranging capybaras.

Rickettsial Infection in Ticks from a National Park in the Cerrado Biome, Midwestern Brazil

This study was carried out from February 2020 to September 2021 in Parque Nacional das Emas (PNE), a national park located in the Cerrado biome, midwestern Brazil, as well as in surrounding rural properties. Serum and tick samples were collected from dogs, terrestrial small mammals, and humans. Ticks were also collected from the environment. Dogs were infested with Rhipicephalus linnaei adults, whereas small mammals were infested by immature stages of Amblyomma spp., Amblyomma triste, Amblyomma dubitatum, and Amblyomma coelebs. Ticks collected from vegetation belonged to several species of the genus Amblyomma, including A. coelebs, A. dubitatum, Amblyomma naponense, Amblyomma sculptum, and A. triste. Two Rickettsia species were molecularly detected in ticks: Rickettsia parkeri in A. triste from the vegetation and a Rickettsia sp. (designated Rickettsia sp. strain PNE) in A. sculptum and A. triste collected from lowland tapirs (Tapirus terrestris). Based on short gltA gene fragments, this rickettsial organism showed 99.7-100% to Rickettsia tillamookensis. Seroreactivity to Rickettsia antigens was detected in 21.9% of dogs, 15.4% of small mammals, and 23.5% of humans. The present study reveals the richness of ticks and demonstrates the circulation of rickettsial agents in one of the largest conservation units in the Cerrado biome in Brazil. To our knowledge, this is the first report of a rickettsial phylogenetically related to R. tillamookensis in Brazil.