Stefan Vilges de Oliveira

Potential Geographic Distribution of Hantavirus Reservoirs in Brazil

Hantavirus cardiopulmonary syndrome is an emerging zoonosis in Brazil. Human infections occur via inhalation of aerosolized viral particles from excreta of infected wild rodents. Necromys lasiurus and Oligoryzomys nigripes appear to be the main reservoirs of hantavirus in the Atlantic Forest and Cerrado biomes. We estimated and compared ecological niches of the two rodent species, and analyzed environmental factors influencing their occurrence, to understand the geography of hantavirus transmission. N. lasiurus showed a wide potential distribution in Brazil, in the Cerrado, Caatinga, and Atlantic Forest biomes. Highest climate suitability for O. nigripes was observed along the Brazilian Atlantic coast. Maximum temperature in the warmest months and annual precipitation were the variables that most influence the distributions of N. lasiurus and O. nigripes, respectively. Models based on occurrences of infected rodents estimated a broader area of risk for hantavirus transmission in southeastern and southern Brazil, coinciding with the distribution of human cases of hantavirus cardiopulmonary syndrome. We found no demonstrable environmental differences among occurrence sites for the rodents and for human cases of hantavirus. However, areas of northern and northeastern Brazil are also apparently suitable for the two species, without broad coincidence with human cases. Modeling of niches and distributions of rodent reservoirs indicates potential for transmission of hantavirus across virtually all of Brazil outside the Amazon Basin.

Rickettsia sp. Strain Atlantic Rainforest Infection in a Patient from a Spotted Fever-Endemic Area in Southern Brazil.

Santa Catarina State in southern Brazil is the state with the second highest number of laboratory-confirmed cases of spotted fever illness in Brazil. However, all these cases were confirmed solely by serological analysis (seroconversion to spotted fever group rickettsiae), which has not allowed identification of the rickettsial agent. Here, a clinical case of spotted fever illness from Santa Catarina is shown by seroconversion and molecular analysis to be caused by Rickettsia sp. strain Atlantic rainforest. This is the third confirmed clinical case due to this emerging rickettsial agent in Brazil. Like the previous two cases, the patient presented an inoculation eschar at the tick bite site. Our molecular diagnosis was performed on DNA extracted from the crust removed from the eschar. These results are supported by previous epidemiological studies in Santa Catarina, which showed that nearly 10% of the most common human-biting ticks were infected by Rickettsia sp. strain Atlantic rainforest.

Rickettsia (Rickettsiales: Rickettsiaceae) Vector Biodiversity in High Altitude Atlantic Forest Fragments Within a Semiarid Climate: A New Endemic Area of Spotted-Fever in Brazil

Abstract Rickettsioses are re-emerging vector-borne zoonoses with a global distribution. Recently, Rickettsia sp. strain Atlantic rainforest has been associated with new human spotted-fever (SF) cases in Brazil, featuring particular clinical signs: eschar formation and lymphadenopathy. These cases have been associated with the tick species, Amblyomma ovale. From 2010 until 2015, the Brazilian Health Department confirmed 11 human SF cases in the Maciço de Baturité region, Ceará, Brazil. The present study reports the circulation of Rickettsia spp. in vectors from this entirely new endemic area for SF. A total of 1,727 ectoparasites were collected in this area from the environment, humans, and wild and domestic animals. Samples (n = 887) were screened by polymerase chain reaction (PCR), targeting the gltA and ompA rickettsial genes. Sequencing and phylogenetic analyses of gltA gene amplicons were carried out for 13 samples positive for both screening PCRs. Fragments of gltA and ompA from three samples were cloned, sequenced, and analyzed further. A. ovale and Rhipicephalus sanguineus specimens, collected from dogs, were found to be infected with Rickettsia sp. str. Atlantic rainforest, suggesting the importance of dogs in the epidemic cycle. Candidatus Rickettsia andeanae, Rickettsia felis, and Rickettsia bellii were also found infecting ticks and fleas in five municipalities, demonstrating the broad diversity of rickettsiae in circulation in the studied area. This study reports, for the first time, evidence of infection with Rickettsia sp. strain Atlantic rainforest in A. ovale and R. sanguineus in Ceará, and Ca. R. andeanae in an Atlantic rainforest environment of Brazil.

Genetic identification of Rickettsia sp. strain Atlantic rainforest in an endemic area of a mild spotted fever in Rio Grande do Sul state, Southern Brazil

Rickettsia sp. strain Atlantic rainforest causes a less severe rickettsiosis, with two cases confirmed until now. The tick species Amblyomma ovale is appointed as the main vector of this bacterium. The southern region of Brazil has reported patients with spotted fever who have milder symptoms. In 2013, during an investigation of rickettsiosis cases, an A. ovale tick was found attached to a man in an area where there were two cases. The parasite was processed for molecular analysis and the rickettsial infection was confirmed based on phylogenetic analysis of genes ompA, ompB and geneD (sca4). In the present study the human pathogenic Rickettsia sp. strain Atlantic rainforest was identified in the state of Rio Grande do Sul, Southern Brazil. Since A. ovale, its main vector, is found frequently parasitizing dogs, animals that can cross international borders freely in southern Brazil, this bacteria can bring major concerns in terms of public health.

A fatal case of Brazilian spotted fever in a non-endemic area in Brazil: the importance of having health professionals who understand the disease and its areas of transmission

Brazilian spotted fever (BSF) is caused by the bacterium Rickettsia rickettsii. Because of its high case-fatality rate and apparent increase in areas of transmission, it is considered to be the rickettsial illness of primary public health interest. Cases of this disease have historically occurred in Southeastern Brazil. This article reports the first fatal case of BSF in Southern Brazil. This case high lights the importance of BSF to be considered as a differential diagnosis for acute hemorrhagic fever in areas where cases of BSF may not be expected.

Effect of piplartine and cinnamides on Leishmania amazonensis, Plasmodium falciparum and on peritoneal cells of Swiss mice

Abstract Context: Plants of the Piperaceae family produce piplartine that was used to synthesize the cinnamides. Objective: To assess the effects of piplartine (1) and cinnamides (2–5) against the protozoa responsible for malaria and leishmaniasis, and peritoneal cells of Swiss mice. Materials and methods: Cultures of Leishmania amazonensis, Plasmodium falciparum-infected erythrocytes, and peritoneal cells were incubated, in triplicate, with different concentrations of the compounds (0 to 256 μg/mL). The inhibitory concentration (IC50) in L. amazonensis and cytotoxic concentration (CC50) in peritoneal cell were assessed by the MTT method after 6 h of incubation, while the IC50 for P. falciparum-infected erythrocytes was determined by optical microscopy after 48 or 72 h of incubation; the Selectivity Index (SI) was calculated by CC50/IC50. Results: All compounds inhibited the growth of microorganisms, being more effective against P. falciparum after 72 h of incubation, especially for the compounds 1 (IC50 = 3.2 μg/mL) and 5 (IC50 = 6.6 μg/mL), than to L. amazonensis (compound 1 = 179.0 μg/mL; compound 5 = 106.0 μg/mL). Despite all compounds reducing the viability of peritoneal cells, the SI were <10 to L. amazonensis, whereas in the cultures of P. falciparum the SI >10 for the piplartine (>37.4) and cinnamides 4 (>10.7) and 5 (= 38.4). Discussion and conclusion: The potential of piplartine and cinnamides 4 and 5 in the treatment of malaria suggest further pre-clinical studies to evaluate their effects in murine malaria and to determine their mechanisms in cells of the immune system.

Vigilância de ambientes da febre maculosa brasileira e outras riquetsioses: a etapa inicial de uma proposta para a formação de rede

OBJECTIVE: Describing the process of structuring the environmental monitoring network of the Brazilian spotted fever and other rickettsial diseases. MATERIALS AND METHODS: Conducting theoretical and practical training talking about collection methods, fixing and transporting vectors; collection and control of hosts and amplifiers for blood collection and the taxonomy of vectors carried out in endemic areas of the disease in Brazil. RESULTS: Ten Brazilian States were qualified (Rio Grande do Sul, Santa Catarina, Paraná, Minas Gerais, Espírito Santo, Distrito Federal, Góias, Mato Grosso, Bahia and Tocantins), 216 professionals were trained and the activities had participants from 85 municipalities and Distrito Federal, which represents 11.48% of the municipalities that register cases of Brazilian spotted fever and other rickettsial diseases. CONCLUSION: The standardization of methods, structuring and strategic ordination of activities for the investigation of cases and environmental monitoring will contribute to the opportunity of epidemiological clinical suspicion and in prevention actions, main factors for reducing morbidity and mortality.

Amblyomma ticks and future climate: Range contraction due to climate warming

Ticks of the Amblyomma cajennense species complex are important vectors of spotted fever in Latin America. Environmental conditions determine the geographic distribution of ticks, such that climate change could influence the distribution of tick-borne diseases. This study aimed to analyze the potential geographic distribution of A. cajennense complex ticks in a Brazil region under present-day and future climate models, assuming dispersal limitations and non-evolutionary adaptation of these tick populations to climate warming. Records of A. cajennense sensu stricto (s.s.) and Amblyomma sculptum were analyzed. Niche models were calibrated using Maxent considering climate variables for 1950-2000 and projecting models to conditions anticipated for 2050 and 2070 under two models of future climate (CCSM4 and HadGEM2-AO). Broad suitable areas for A. cajennense s.s. and A. sculptum were found in present-day climate models, but suitability was reduced when models were projected to future conditions. Our exploration of future climates showed that broad areas had novel climates not existing currently in the study region, including novel extremely high temperatures. Indeed, predicted suitability in these novel conditions would lead to biologically unrealistic results and therefore incorrect forecasts of future tick-distribution. Previous studies anticipating expansions of vectors populations due to climate change should be considered with caution as they assume that model extrapolation anticipates that species would evolve rapidly for adaptation to novel climatic conditions.

Ten years of a hantavirus disease emergency in the Federal District, Brazil

INTRODUCTION Hantavirus diseases are emerging human diseases caused by Hantavirus spp. of the Bunnyaviridae family. Hantavirus pulmonary syndrome (HPS) has been detected in the Federal District (DF) of Brazil since 2004. Among the 27 Brazilian Federal Units, DF has the highest fatality rate. More than 10 years have already passed since then, with confirmation of cases caused by the Araraquara and Paranoa species. The reservoir is Necromys lasiurus. METHODS Local surveillance data of the confirmed cases were analyzed, including age, sex, month and year of occurrence, clinical symptoms, syndromes and outcomes, and probable transmission place (PTP). The cases were mainly confirmed by IgM detection with a capture enzyme immunoassay. The cases were classified as autochthonous if PTPs were in the DF area. RESULTS From 2004 to 2013, in the DF, 126 cases of hantavirus were confirmed, and the cumulative incidence was 5.0 per 100,000 inhabitants. The occurrence of cases was predominantly from April to August. At least 75% of the cases were autochthonous. Acute respiratory failure was reported in 47.5% of cases, and the fatality rate was 40%. CONCLUSIONS In the DF, the cumulative incidence of HPS was one of the highest worldwide. A seasonal pattern of hantavirus disease in the dry season is clear. There was a high frequency of severe clinical signals and symptoms as well as a high fatality rate. For the near future, visitors and inhabitants of DF rural areas, particularly male adults, should receive continuous education about hantavirus transmission and prevention.

Vulnerability of Brazilian municipalities to hantavirus infections based on multi-criteria decision analysis

BackgroundHantavirus infection is an emerging zoonosis transmitted by wild rodents. In Brazil, high case-fatality rates among humans infected with hantavirus are of serious concern to public health authorities. Appropriate preventive measures partly depend on reliable knowledge about the geographical distribution of this disease.MethodsIncidence of hantavirus infections in Brazil (1993–2013) was analyzed. Epidemiological, socioeconomic, and demographic indicators were also used to classify cities’ vulnerability to disease by means of multi-criteria decision analysis (MCDA).ResultsFrom 1993 to 2013, 1752 cases of hantavirus were registered in 16 Brazilian states. The highest incidence of hantavirus was observed in the states of Mato Grosso (0.57/100,000) and Santa Catarina (0.13/100,000). Based on MCDA analysis, municipalities in the southern, southeastern, and midwestern regions of Brazil can be classified as highly vulnerable. Most municipalities in northern and northeastern Brazil were classified as having low vulnerability to hantavirus cardiopulmonary syndrome.ConclusionsAlthough most human infections by hantavirus registered in Brazil occurred in the southern region of the country, a greater vulnerability to hantavirus was found in the Brazilian Midwest. This result reflects the need to strengthen surveillance where the disease has thus far gone unreported.