Spotted Fever: Epidemiology and Vector-Rickettsia-Host Relationship in Rio de Janeiro State

Abstract

The eco-epidemiological scenario of spotted fever (SF), a tick-borne disease that affects humans and other animals in several countries around the world, was analyzed in Rio de Janeiro (RJ) State, Brazil. During the last 34 years, 990 SF cases were reported in RJ (the Brazilian state with the highest population density), including 116 cases confirmed by serology (RIFI) or PCR, among 42.39% of the municipalities with reported cases of SF. The epidemiologic dynamics of SF in RJ State are very heterogeneous in time and space, with outbreaks, high mortality rates and periods of epidemiological silence (no SF cases reported). Furthermore, it exhibited a changing epidemiological profile from being rural to becoming an urban disease. This study identified arthropods infected with Rickettsia felis, R. bellii and R. rickettsii, and found that the abundance of ectoparasites was associated with specific hosts. The R. rickettsii-vector-host relationship was most evident in species-specific parasitism. This suggests that the association between dogs, cattle, horses, capybaras and their main ectoparasites, Rhipicephalus sanguineus and Ctenocephalides felis, Rhipicephalus microplus, Dermacentor nitens, and Amblyomma dubitatum, respectively, has a key role in the dynamics of R. rickettsii transmission in enzootic cycles and the maintenance of carrier ectoparasites, thus facilitating the existence of endemic areas with the ability to produce epidemic outbreaks of SF in RJ. This study found confirmed human infections for only the R. rickettsii carrier Amblyomma sculptum, which reinforces the importance of this species as a vector of the pathogen in Brazil. This study can be adapted to different eco-epidemiological scenarios of spotted fever throughout the Americas.

Biodiversity of Potential Vectors of Rickettsiae and Epidemiological Mosaic of Spotted Fever in the State of Paraná, Brazil

“…In this context, the analysis of the frequency of cases in PR shows the presence of three frequency patterns (2006-2009, 2010-2014, and 2015-2017) (Figure 3). These have also been detected in other studies (9,42), and show a direct relationship between public health actions and increases in SFR notifications, especially once Ordinance 1,271 of the Ministry of Health, of June 6, 2014 (11), redefined the classification of the disease as once requiring immediate compulsory notification (within 24 h). Likewise, our results indicate that the temporal distribution of notified cases is greater between August (penultimate month of winter) and December (late spring and early summer), with a peak in October (second month of spring) (Figure 4).…”

“…As is common in other states in Brazil (9), for most cases analyzed here, serology was used as the confirmatory criterion. However, this diagnostic method does not determine the species of bioagent, and the results must be interpreted within an epidemiological clinical context, since identification of the tick with which the patient was in contact with remains important when confirming SFR infection (42,67,69,70). However, contact with capybaras, present in 5.40% (2/37) of the reports in this study, does not seem to be a relevant factor in SFR infections in PR, though they have been reported as so in RJ (42).…”

Evaluating the Surveillance System for Spotted Fever in Brazil Using Machine-Learning Techniques

“…In fact, laboratory tests confirmed cases for dengue and leptospirosis, 53.3% (8/15) and 62.5% (5/8), respectively, in which subjects had also had contact with ticks. However, contact with ticks as a historical factor of suspected SF remains important ( 3 , 25 , 26 ), while contact with capybaras, present in 1.7% (2/104) of cases, is not a relevant factor in suspected SF in the state of RJ ( 27 ), as established in the surveillance protocols for Brazil ( 4 , 5 , 21 , 22 ).…”

Exposure of Baixadeiro horses to Rickettsia spp. and to ticks infected by Rickettsia amblyommatis in the Baixada Maranhense micro-region, Maranhão, Brazil

“…is of great medical importance in Brazil, since Rickettsia amblyommatis presents an association with A. cajennense s.s and R. rickettsii presents an association with A. sculptum. R. rickettsii is the most important etiological agent for spotted fever in the Americas (MARTINS et al, 2016;LABRUNA, 2009;MONTENEGRO et al, 2017). There have been a few reports of A. sculptum infected with R. amblyommatis in the Atlantic rainforest, Cerrado and Pantanal biomes (ALVES et al, 2014;NUNES et al, 2015;RAMOS et al, 2015;WITTER et al, 2016).…”

“…Horses are commonly considered to be the primary host of these two tick species. In Brazil, they have an important sentinel role for Brazilian spotted fever (BSF) (SANGIONI et al, 2005;UENO et al, 2016;MONTENEGRO et al, 2017).…”