Spotted Fever in the Morphoclimatic Domains of Minas Gerais State, Brazil

In Brazil, the tick-borne rickettsiosis known as Spotted Fever (SF) has been recorded from 59% of the Federative Units, however, the knowledge of the epidemiology and dynamics of human infection remains incipient in certain areas, complicating appropriate public health actions to inform the general population and control the disease. Here, we improved the interpretation of epidemiological information of SF cases recorded for an important endemic area. A descriptive epidemiological study was carried out based on records in the SINAN (Notifiable Diseases Information System) SF case databases. Data analysis was performed using Python programming language, Pandas library and Qgis map making. To evaluate the sociodemographic, clinical, assistance, laboratory and epidemiological characteristics, simple and relative nominal values of occurrences, means and standard deviations, and molecular analyzes were performed to identify the bioagent present in biological samples collected during each case investigation. Of the 298 confirmed cases, 98 resulted in death, the number of cases increased from 2011, and the disease scenario had 32.8% lethality. Overall, 207 cases involved men, and lethality was higher in this group. The most affected age group was 30 to 59 years old. The majority of patients reported having had contact with animals such as ticks, capybara and domestic animals such as dogs and cats. The results corroborate existing studies in areas of severe SF cases in Brazil. Despite reports of SF cases from the Cerrado Biome, analyses show that serious cases occur in anthropized areas of the Atlantic Forest biome, and in a transition area between this and the Cerrado. Complex, longitudinal, multidisciplinary studies, with an eco-epidemiological focus, should be carried out to allow the construction of algorithms capable of predicting, in time and space, the risk factors associated with severe cases and deaths from SF, with the aim of avoiding their expansion.

Introduction

In Brazil, Spotted Fever (SF) has been recorded from 59% of the Federative Units (16/27), with the Southeast and South regions of the country reporting the most cases (1). Three epidemiological scenarios are recognized for SF in Brazil. The first, with severe cases and deaths, occurs in anthropized areas in the Southeast and part of the South (northern Paraná). The bacterium Rickettsia rickettsii is the etiological agent and the tick Amblyomma sculptum the vector. In this scenario, horses and capybaras are important for the maintenance of A. sculptum in nature. Furthermore, in these areas, capybara is the main amplifier of R. rickettsii. The second scenario, also with serious cases and deaths, is restricted to the metropolitan region of São Paulo, in areas of Atlantic forest fragments and their surroundings, where R. rickettsii is transmitted by Amblyomma aureolatum. Here, humans become infected when dogs, with free access to the environment, carry the infected vector to their homes and humans. The third scenario involves less severe cases that occur mainly in areas with Atlantic forest fragments, or in their surroundings, in areas of the South, Southeast and Northeast regions, where Rickettsia parkeri strain Atlantic forest is transmitted by Amblyomma ovale (2–9). A probable fourth scenario may occur in the Pampa biome, involving R. parkeri sensu stricto, Amblyomma tigrinum and dogs. The cases are considered mild and the probable site of infection (PSI) appears to be the rural environment or forest area/forest edge (7, 10).

However, knowledge of the epidemiology and dynamics of human infection remains insipient in the various PSIs across the country (2), complicating appropriate public health actions to inform the general population and control the disease. In addition, studies progressed, different species of Rickettsia spp./Spotted Fever group, related to different species of ticks, have been detected in Brazil, whether or not they are linked to SF outbreaks (6, 7, 11–15). This has demonstrated the great biodiversity of Rickettsiae and potential vectors, and highlighting the potential complexity of the mechanisms by which these microorganisms might circulate within the country, and the danger for the appearance of new outbreaks.

The State of Minas Gerais has the third largest number of confirmed SF cases, ranking second in Brazil for the number of SF deaths (1). The disease has been known in the State since the 1930s, occurring in several regions, and showing a variety of clinical symptoms. Different species of infected Rickettsiae and ectoparasites have already been reported for the State (1, 16–19). However, in most instances, the circulating bioagent is not identified, nor are studies undertaken that would allow a greater understanding of the eco-epidemiological aspects. Accordingly, this article aims to improve interpretation of the epidemiological information of SF cases recorded for the Minas Gerais State using case records from January 2007 to November 2019, and to understand the vectors and etiological agents involved in the disease cycle within the State. In this sense, the interpretation described here contributes to a better understanding of the behavior of the disease, and can contribute positively to Brazilian epidemiological surveillance programs.

Methods

A descriptive epidemiological study was carried out using SF case records in the databases using the Notification and Investigation forms (NIF) placed on SINAN (Notifiable Diseases Information System)between January 2007 and November 2019. Confirmed cases of the disease were analyzed over the study period, that is, cases in which the symptoms and epidemiological history matched the definition of a suspected case and when the Rickettsia infection of the spotted fever (SFG) group was established. The study was carried out by analyzing cases that occurred in the 82 municipalities of the Minas Gerais State that had confirmed cases between 2007 and 2019, noting whether the municipalities those where patients resided, and also whether the probable infection sites of the confirmed SF cases occurred in these municipalities (Figure 1).

FIGURE 1

Figure 1 Municipalities in the State of Minas Gerais with cases and death records due to spotted fever between 2007 and 2019 (November).

Descriptive Study

An epidemiological study of confirmed SF cases was carried out between January 2007 and November 2019, in the State of Minas Gerais. The SINAN database and Technical reports of the investigations carried out by epidemiological surveillance teams of the Municipal Health Secretariats and the State Health Secretariat were used as data sources.

Data analysis was performed using the Python 3.6.8 programming language, Pandas 0.24.2 library, and using Qgis^® 2.18.11 software to map cases of the disease and their locations in morphoclimatic domains of the State. For the evaluation of sociodemographic, clinical, care, laboratory, and epidemiological characteristics, we calculated simple and relative nominal values of occurrences, means, and standard deviations.

The variables associated with confirmed cases were analyzed using the following classification (1): General data on the origin of patients (Municipality of Notification); Individual data (age, sex and ethnicity); clinical data (main signs and symptoms); epidemiological data (specifically related to risk exposures); Conclusive data (evolution of 104 individual cases).

Molecular Studies

A total of 304 blood samples from human patients and 1,612 samples of A. sculptum ticks, collected in places with suspected or confirmed cases of FM, during case investigation and environmental surveillance from suspected SF cases in the State of Minas Gerais, from 2017 to 2018, were analyzed. The sampling units for collection of potential ectoparasite vectors consisted of specimens from the same host or environment. Adult vectors were packaged and processed individually, nymphs in pools of 10 individuals and larvae in pools of 100 individuals.

Genomic DNA was extracted from samples using the DNeasy Blood and Tissue Kit (Qiagen) and subjected to quantitative Polymerase Chain Reaction (qPCR), using KAPA SYBR FAST qPCR Kit (Sigma-Aldrich) and oligonucleotides to detect Rickettsiae: gltA (RpCS.877P/RpCS.1258N) (20), htrA (17k-5/17k-3 (21), and ompA (Rr 190.70p/Rr 190.602n) (22).

Samples positive for at least one of the genes in the qPCR were subjected to amplification reactions of fragments of rickettsial genes gltA (CS-78/CS-323 (23) and CS-239/CS-1069 (21)), sca4 (D1738F/D2482R) (24) and ompA(Rr 190.70p/Rr 190.602n) (22). In all amplification reactions, 300 ng of R. parkeri DNAg was used, as a positive control, and ultra-pure water free of DNase and RNase, as a negative control.

Amplicons of the expected sizes were purified using the Wizard SV Gel and PCR Clean-Up TM System Protocol Kit (Promega), following the manufacturer’s guidelines, and subjected to a sequencing reaction using Big Dye Terminator Cycle Sequencing Kit v3.1 (Applied Biosystems). Nucleotide sequences were read by an automatic ABI 3730xl DNA analyzer (Applied Biosystems) from the Sequencing Platform (PDTIS) of the Oswaldo Cruz Foundation. Obtained Sequences were edited using the SeqMan™ II program (DNASTAR package, Lasergene), and identity of the sequences was assessment via comparative analysis with existing rickettsial sequences held in GenBank (BLASTn). Phylogenetic inferences were made using Maximum Likelihood, with an evolutionary model GTR+G, selected through the Bayesian Information Criterion, and indicated by the MEGA 7.0 22 program. Internal branches support values were calculated using a 1,000 replica bootstrapping procedure.

Ethical Considerations

Data collection in this study obeyed Resolution 466/2012 (Ministry of Health of Brazil), guaranteeing the confidentiality of information and non-disclosure of individual patient data.

Results

Between 2007 to 2019 (November), 298 cases of SF were confirmed in the State of Minas Gerais, Brazil. Of these, 98 ended in deaths. An increase in the number of cases was observed from the year 2011 on (Figure 2A). The SF scenario in the State had a lethality of 32.8%, with the Municipality of Belo Horizonte having the highest number of cases: 63, and the Municipality of Juiz de Fora the highest lethality: 48.1%. Overall, 207 (69.4%) cases involved males, with lethality being higher in this group, 78.8% (n = 78). The age group most affected was 30 to 59 years old, the average age of individuals in cases that died was 39 years old, with a standard deviation of 18.7 (Table 1). The average age of individuals in cases of recovery was 31.6 years, with a standard deviation of 20.6. The greatest number of cases occurred between August and November, the most severe cases that died, during September and December (Figure 2B).

FIGURE 2

Figure 2 Epidemiological dynamics of Spotted Fever in the State of Minas Gerais, 2007–2019 (November): (A) Absolute number of reported cases, deaths, and SF lethality rate; (B) Monthly distribution of SF cases; (C) Contact with animals × disease evolution.

TABLE 1

Table 1 Absolute and relative frequency of confirmed cases and deaths from Spotted Fever, based on individual, demographic and epidemiological variables from 2007 to 2019 in the State of Minas Gerais, Brazil.

Most patients reported having had contact with wild animals such as ticks, capybara, and domestic animals such as dogs and cats. In cases that ended in death, contact with dogs and cats was most common (89 cases) followed by contact with ticks (74 cases) and horses (35 cases). Contact with capybaras ranks lowest in contact records. This was true both for patients who recovered and those who did not (Figure 2C).

In qPCR screens, 99 samples (human blood and ticks) were positive for the presence of Rickettsia spp. These subsequently underwent conventional PCR to search for rickettsial genes. Of these, 85 samples were positive for at least one of the searched-for genes; it being possible to obtain partial nucleotidesequences of the following—gltA in 85 samples (MT957958-MT958042), ompA in 66 samples (MT958043-MT958108) and from the sca4 gene 56 samples 175 (MT958109-MT958164) (Table 2).

TABLE 2

Table 2 Rickettsia rickettsii detected by analysis of partial nucleotide sequences of the gltA, ompA, and sca4 genes from blood (human) and tick (Amblyomma sculptum) samples from areas of suspected Spotted Fever cases in the state of Minas Gerais, from 2017 to 2018.

BLAST analyzes showed that all sequences obtained in this study were identical and showed 100% similarity to R. rickettsii cepa Brasil (CP003305) sequences, and other strains of this species available in Genbank. Accordingly, sequences from three samples were selected for the phylogenetic reconstruction generated from comparison of concatenated partial sequences of the gltA, ompA, and sca4 genes (of 1,106, 491, and 704 bp, respectively), demonstrating that the sequences from Minas Gerais obtained here are phylogenetically related to the R. rickettsii group (Figure 3).

FIGURE 3

Figure 3 Phylogenetic inferences from the comparison of the concatenated partial sequences of the gltA, ompA, and sca4 genes (of 1,106, 491, and 704 bp, respectively) of human patients’ blood, from suspected Spotted Fever cases in the State of Minas Gerais, between 2017 and 2018, using the maximum likelihood method of 1,000 replicated trees. As an evolutionary model, the GTR + G + I algorithm was used, and bootstrap values above 70% are shown in the branches. Sequences obtained in this study are highlighted in bold, preceded by the respective GenBank accession numbers, and followed by information about the case location.

None of the samples (human blood or ticks) tested positive for the presence of Rickettsia spp. came the from Cerrado biome.

Discussion

In 2007, SF began to be recorded on SINAN and in 2011, training on rickettsiosis environment surveillance began in the country as did the incorporation of molecular diagnostic techniques, which enabled the unambiguous identification of deaths from the disease. This timeline may explain the increase in recorded mortality rates after 2011, observed in the present study (1).

There was a considerable increase in the number of SF cases in the State from 2014. This was because, in June of that year that, Ordinance No. 1,271 made the immediate notification of SF compulsory, with other rickettsioses disease being notifiable within 24 h (1). The increase in the number of notifications is the result of efforts promoted by SUS (Health Unic System), which develops continuous training processes and improves epidemiological surveillance network structure (22). As pointed out in the present study, the increase in SF lethality in recent years in both Brazil, and in the State of Minas Gerais, shows the severity of the recent cases (Figure 2A). The present study demonstrated that the majority of SF victims, fatal or not, are male, which is in agreement with the results for the disease in Brazil (2). The most affected ethnic groups were brown, followed by whites. However, it is worth mentioning that, on very dark skins, the maculating rash is not easily identified, which can cause difficulties in the diagnosis in this portion of the population (23). In MG State, cases are concentrated in the portion of the population with the lowest level of education, up to incomplete elementary school. In the current study, it was notable how cases were concentrated in urban areas, corroborating findings similar studies in several regions of the country. This demonstrates a potential urbanization of the disease, which has been occurring in regions that had not previously been considered to be at risk of transmission, which suggests that the disease is now occurs not just rurally, but also in peri-urban and urban areas, including public parks (24–26) (Table 1).

The greatest number of cases was recorded between the months of August and November, a period in which the highest density of A. sculptum nymphs (27, 28) is generally recorded. This may be linked to disease transmission to humans since the nymphs’ bite is less painful than that of an adult, and may, indeed, be imperceptible.

In Brazil the SF epidemiological scenario is diverse, involving different species of vectors and Rickettsiae, with cases ranging from moderate to severe, and with deaths occurring. For example, in degraded areas and the Cerrado bioma, in the southeastern region and part of the southern region (northern Paraná state), the most severe form of the disease occurs, and R. rickettsii, A. sculptum, capybaras and horses may be involved in the epidemic cycle, especially in rural and peri-urban environments. Capybaras occur in several biomes in preserved and anthropized areas including urban areas of Minas Gerais as observed in Juiz de Fora and Belo Horizonte municipalities. In the present study, contact with capybaras did not appear as a relevant factor in the suspicion of FM, both in mild cases and in cases that progressed to death, as was also noted in RJ and Paraná (29, 30). However, direct contact with capybaras is not necessary for human tick bite to occur. Capybaras can be shy and cautious in hostile environments and spread ticks, infected or not, in the environment without being seen. Serious cases and deaths are also associated with the transmission of R. rickettsii by A. aureolatum in a less anthropized area of the Atlantic Forest, in the metropolitan region of São Paulo, with the infected tick vectors when these ticks are carried by dogs into the anthropic environment, especially households close to the forests, and, this close relationship between humans and hosts, especially dogs, is characterized as one of the main risk exposure factors (2–4, 30, 31).

Moderate cases are associated with the transmission of R. parkeri by A. ovale, in an area with less anthropic impact on the Atlantic forest biome in the South, Southeast and Northeast regions of the country, especially in the coastal areas. In addition, there is evidence that A. tigrinum can participate in the transmission of R. parkeri in the Pampa biome, in southern Brazil. In these scenarios, dogs can take the infected tick to the anthropic environment or humans become infected when entering natural foci (2, 3, 5, 6, 32, 33). However, in other areas of the national territory, such as in the Cerrado biomes (Midwest region), Amazon, and Caatinga, the epidemiological scenarios are not defined, and there may be clinical variation, absence of species known as Rickettsiae vectors or pathogenic Rickettsia (2, 4, 20, 34).

The State of Minas Gerais is characterized by having severe cases and deaths from SF spread over a large area of the State, and also both the Cerrado and the Atlantic Forest biomes. However, the analysis of the spatial distribution, according to the morphoclimatic domains, shows deaths to have occurred only in the area of the Atlantic Forest biome and in the transition area between the Atlantic Forest and the Cerrado, with no record of deaths in the area of pure Cerrado biome within the State (Figure 1). Likewise, in Brazil in general, by far the greatest majority of serious cases and deaths from SF are spatially distributed in the Atlantic Forest, or in transition zones between this and the Cerrado (2–4, 30, 31).

The factors associated with the absence of records for serious cases and deaths in the typical Cerrado region of Minas Gerais are not clear. However, while, it is unusual to record R. rickettsii in typical areas of this biome [16], A. sculptum, considered its main vector, is found throughout the Cerrado region and does not have its own genetic structure for its population in this region (8, 34, 35). Additionally, horses and capybaras, considered the main vertebrates in the Brazilian spotted fever epidemic cycle, are traditionally present in this biome. Therefore, all biotic predisposing factors for enzootic and epidemic cycle to occur are present in the Cerrado. However, there is no circulation of R. rickettsii, the determining factor in the disease cycles.

However, there are other clinical manifestations seen for Cerrado-based cases (2), signaling the possibility of the involvement of another species of Rickettsia in this biome.

Thus, it is possible that ecological factors are influencing the spatial distribution of R. rickettsii and, consequently, restricting serious cases and deaths to the most densely populated area of the State of Minas Gerais. In such locations there should be greater attention from health services to record SF cases, control and prevent them, and seek to reduce the lethality level. In addition, complex multidisciplinary, longitudinal studies, associated with eco-epidemiology, should be carried out in the search for the construction of algorithms capable of predicting, in time and space, the risk factors associated with severe cases and deaths from SF, and so avoid the expansion of this disease.

Conclusion

The results corroborate existing studies in areas of severe cases of DES in Brazil. Despite the case reports of SF from the Cerrado biome in MG, the analyzes show that severe cases occur in anthropized areas of the Atlantic Forest biome and in a transition area between this and the Cerrado. The finding of only A. sculptum in the areas of cases of the disease may suggest the strong relationship of this vector in severe cases of FS in MG. These results may suggest an eco-epidemiological scenario, apparently more similar to Brazilian cases of spotted fever related to A. aureolatum as a vector in other states, and, it is not possible to completely rule out other possible vectors of the disease in the state without a systematic long-term study. Complex, longitudinal, multidisciplinary studies, with an eco-epidemiological focus, should be carried out to allow the construction of algorithms capable of predicting, in time and space, the risk factors associated with severe cases and deaths from SF, in order to avoid their expansion.

Data Availability Statement

The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found below: https://www.ncbi.nlm.nih.gov/genbank/MT957958–MT958164/.

Ethics Statement

Ethical review and approval was not required for the study on human participants in accordance with the local legislation and institutional requirements. Written informed consent for participation was not required for this study in accordance with the national legislation and the institutional requirements.

Author Contributions

EN, NM-M, FM, and GG designed the study, interpreted the results and wrote the article. FI performed the real-time amplification screening. NM-M performed the molecular and phylogenetic analysis. AD and SO collected and analyzed the clinical and epidemiological data of the cases. All authors contributed to the article and approved the submitted version.

Funding

EN is a graduate fellow supported by the PROQUALI program of the Federal University of Juiz de Fora (UFJF) (Grants 23071.902525/2020-94 and 23071.903542/2021-83) and this work is part of her PhD thesis at UFJF.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Acknowledgments

The authors would like to thank to Dr. Adrian Paul Ashton Barnett for the English review and comments; to the Health Department of Minas Gerais for providing Spotted Fever cases data; to Ezequiel Dias Foundation for its support during the screening and analysis of the cases; and to Genomic Platform DNA Sequencing (PDTIS/Oswaldo Cruz Foundation, Rio de Janeiro, Brazil) for sequencing support.

References

1. Ministério da Saúde do Brasil. Guia De Vigilância Em Saúde: Febre Maculosa Brasileira E Outras Riquetsioses (2020). Available at: http://portalsaude.saude.gov.br/images/pdf/2015/fevereiro/06/guiavigilanciasaude-atualizado-05-02-15.pdf (Accessed January 02, 2021).

Google Scholar

2. Oliveira SV, Guimarães JN, Reckziegel GC, Da Costa Neves BM, De Araújo-Vilges KM, Fonseca LX. An Update on the Epidemiological Situation of Spotted Fever in Brazil. J Venom Anim Toxins Incl Trop Dis (2016) 22(1):22. doi: 10.1186/s40409-016-0077-4

PubMed Abstract | CrossRef Full Text | Google Scholar

3. Szabó MPJ, Pinter A, Labruna MB. Ecology, Biology and Distribution of Spotted-Fever Tick Vectors in Brazil. Front Cell Infect Microbiol (2013) 3:27. doi: 10.3389/fcimb.2013.00027

PubMed Abstract | CrossRef Full Text | Google Scholar

4. Oliveira SV, Caldas EP, Colombo S, Gazeta GS, Labruna MB, Santos FC, et al. 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. Rev Soc Bras Med Trop (2016) 49(5):653–328. doi: 10.1590/0037-8682-0088-2016

PubMed Abstract | CrossRef Full Text | Google Scholar

5. Luz HR, Faccini JLH, McIntosh D. Molecular Analyses Reveal an Abundant Diversity of Ticks and Rickettsial Agents Associated With Wild Birds in Two Regions of Primary Brazilian Atlantic Rainforest. Ticks Tick Borne Dis (2017) 8:657. doi: 10.1016/j.ttbdis.2017.04.012

PubMed Abstract | CrossRef Full Text | Google Scholar

6. Moerbeck L, Vizzoni VF, Machado-Ferreira E, Cavalcante RC, Oliveira SV, Soares CAG, et al. Rickettsia (Rickettsiales: Rickettsiaceae) Vector Biodiversity in High Altitude Atlantic Forest Fragments Within a Semiarid Climate: A New Endemic Area of Spotted-Fever in Brazil. J Med Entomol (2016) 53:1458–66. doi: 10.1093/jme/tjw121

PubMed Abstract | CrossRef Full Text | Google Scholar

7. da Paixão Sevá A, Martins TF, Muñoz-Leal S, Rodrigues AC, Pinter A, Luz HR, et al. A Human Case of Spotted Fever Caused by Rickettsia Parkeri Strain Atlantic Rainforest and Its Association to the Tick Amblyomma Ovale. Parasit Vectors (2019) 12(1):471. doi: 10.1186/s13071-019-3730-2

PubMed Abstract | CrossRef Full Text | Google Scholar

8. Polo G, Mera Acosta C, Labruna MB, Ferreira F. Transmission Dynamics and Control of Rickettsia Rickettsii in Populations of Hydrochoerus Hydrochaeris and Amblyomma Sculptum. PLoS Negl Trop Dis (2017) 11(6):e0005613. doi: 10.1371/journal.pntd.0005613

PubMed Abstract | CrossRef Full Text | Google Scholar

9. Luz HR, Costa FB, Benatti HR, Ramos VN, de A Serpa MC, Martins TF, et al. Epidemiology of Capybara-Associated Brazilian Spotted Fever. PLoS Negl Trop Dis (2019) 13(9):e0007734. doi: 10.1371/journal.pntd.0007734

PubMed Abstract | CrossRef Full Text | Google Scholar

10. Weck B, Krawczak FS, Costa FB, Dall'Agnol B, Marcili A, Reck J, et al. Rickettsia Parkeri in the Pampa Biome of Southern Brazil: Isolation, Molecular Characterization, and Serological Evidence of Canine Infection. Vet Parasitol Reg Stud Rep (2020) 22:100448. doi: 10.1016/j.vprsr.2020.100448

CrossRef Full Text | Google Scholar

11. Machado IB, Bitencourth K, Cardoso KM, Oliveira SV, Santalucia M, Marques SFF, et al. Diversity of Rickettsiae and Potential Vectors of Spotted Fever in an Area of Epidemiological Interest in the Cerrado Biome, Midwestern Brazil. Med Vet Entomol (2018) 32(4):481–9. doi: 10.1111/mve.12315

PubMed Abstract | CrossRef Full Text | Google Scholar

12. Moerbeck L, Vizzoni VF, Oliveira SV, Cavalcante R, Coelho GCB, Duarte NFH, et al. Rickettsia Sp. Strain NOD Infecting Ticks (Amblyomma Nodosum) in an Endemic Area of Spotted Fever in Brazil. J Wild Dis (2018) 54(2):406–9. doi: 10.7589/2017-06-137

CrossRef Full Text | Google Scholar

13. Bitencourth K, Amorim M, Oliveira SV, Voloch CM, Gazêta GS. Genetic Diversity, Population Structure and Rickettsias in Amblyomma Ovale in Areas of Epidemiological Interest for Spotted Fever in Brazil. Med Veterinary Entomol (2019) 33(2):256–68. doi: 10.1111/mve.12363

CrossRef Full Text | Google Scholar

14. Borsoi ABP, Bitencourth K, Oliveira SV, Amorim M, Gazêta GS. Human Parasitism by Amblyomma Parkeri Ticks Infected With Candidatus Rickettsia Paranaensis, Brazil. Emerg Infect Dis (2019) 25(12):2339–41. doi: 10.3201/eid2512.190988

PubMed Abstract | CrossRef Full Text | Google Scholar

15. Sato TP, Moura-Martiniano NO, Vizzoni VF, Silva AB, Oliveira SV, Amorim M, et al. Rhipicephalus (Boophilus) Microplus: Rickettsiae Infection in Brazil. Int J Acarol (2020) 46(2):88–381. doi: 10.1080/01647954.2020.1720289

CrossRef Full Text | Google Scholar

16. Galvão MAM, Silva LJD, Nascimento EMM, Calic B, Sousa RD, Bacellar F. Riquetsioses No Brasil E Portugal: Ocorrência, Distribuição E Diagnóstico. Rev Saúde Pública (2005) 39:850–6. doi: 10.1590/S0034-89102005000500023

PubMed Abstract | CrossRef Full Text | Google Scholar

17. Galvão MAM, Cardoso LD, Mafra CL, Calic SB, Walker DH. Revisiting Brazilian Spotted Fever Focus of Caratinga, Minas Gerais State, Brazil. Ann NY Acad Sci (2006) 1078:255–6. doi: 10.1196/annals.1374.045

PubMed Abstract | CrossRef Full Text | Google Scholar

18. Nunes EDC, Vizzoni VF, Navarro DL, De Melo Iani FC, Durães LS, Daemon E, et al. Rickettsia Amblyommii Infecting Amblyomma Sculptum in Endemic Spotted Fever Area From Southeastern Brazil. Mem Inst Oswaldo Cruz (2015) 110:1058–61. doi: 10.1590/0074-02760150266

PubMed Abstract | CrossRef Full Text | Google Scholar

19. Zeringóta V, Maturano R, Luz HR, Senra TO, Daemon, Faccini JL, et al. Molecular detection of Rickettsia Rhipicephali and Other Spotted Fever Group Rickettsia Species in Amblyomma Ticks Infesting Wild Birds in the State of Minas Gerais, Brazil. Ticks Tick Borne Dis (2017) 8(1):81–9. doi: 10.1016/j.ttbdis.2016.10.001

PubMed Abstract | CrossRef Full Text | Google Scholar

20. Roux V, Rydkina E, Eremeeva M, Raoult D. Citrate Synthase Gene Comparison, a New Tool for Phylogenetic Analysis, and Its Application for the Rickettsiae. Int J Syst Evol Microbiol (1997) 47:252–61. doi: 10.1099/00207713-47-2-252

CrossRef Full Text | Google Scholar

21. Kumar S, Stecher G, Tamura K. MEGA7: Molecular Evolutionary Genetics Analysis Version 7.0 for Bigger Datasets. Mol Biol Evol (2016) 33(7):1870–4. doi: 10.1093/molbev/msw054

PubMed Abstract | CrossRef Full Text | Google Scholar

22. Oliveira SV, Pereira SVC, Silva PMRB, Pereira JM, Gomes V, Amorim M, et al. Vigilância De Ambientes Da Febre Maculosa Brasileira E Outras 19 Riquetsioses: A Etapa Inicial De Uma Proposta Para a Formação De Rede. Rev Pan-Amaz Saúde (2015) 6(3):67–71. doi: 10.5123/S2176-62232015000300009

CrossRef Full Text | Google Scholar

23. Favacho ARM, Rozental T, Calic SB, Scofield MAM, Lemos ERS. Fatal Brazilian Spotless Fever Caused by Rickettsia Rickettsii in a Dark-Skinned Patient. Rev Soc Bras Med Trop (2011) 44(3):395–428.396. doi: 10.1590/s0037-86822011000300028

PubMed Abstract | CrossRef Full Text | Google Scholar

24. Souza CE, Calic SB, Camargo MCGO, Savani ESM, Souza SSL, Lima VLC, et al. O Papel Da Capivara Hydrochaeris Hydrochaeris Na Cadeia Epidemiológica Da Febre Maculosa Brasileira. Rev Bras Parasitol Vet (2004) 13(Suppl 1):203–5.

Google Scholar

25. Amâncio FF, Amorim VD, Chamone TL, Brito AG, Calic SB, Leite AC, et al. Aspectos Epidemiológicos Dos Casos De Febre Maculosa Brasileira Ocorridos Em Minas Gerais, Brasil, 2000 a 2008. Cad Saúde Pública (2011) 27(10):1969–76. doi: 10.1590/S0102-311X2011001000010

PubMed Abstract | CrossRef Full Text | Google Scholar

26. Labruna MB, Krawczak FS, Gerardi M, Binder LC, Barbieri ARM, Paz GF, et al. Isolation of Rickettsia Rickettsii From the Tick Amblyommasculptum From a Brazilian Spotted Fever-Endemic Area in the Pampulha Lake Region, Southeastern Brazil. Vet Parasitol Reg Stud Rep (2017) 8:82–5. doi: 10.1016/j.vprsr.2017.02.007

CrossRef Full Text | Google Scholar

27. Labruna MB, Kasai N, Ferreira F, Faccini JL, Gennari SM. Seasonal Dynamics of Ticks (Acari: Ixodidae) on Horses in the State of São Paulo, Brazil. Vet Parasitol (2002) 105(1):65–77. doi: 10.1016/s0304-4017(01)00649-5

PubMed Abstract | CrossRef Full Text | Google Scholar

28. de Paula LGF, Zeringóta V, Sampaio ALN, Bezerra GP, Barreto ALG, dos Santos AL, et al. Seasonal Dynamics of Amblyomma Sculptum in Two Areas of the Cerrado Biome Midwestern Brazil, Where Human Cases of Rickettsiosis Have Been Reported. Exp Appl Acarol (2021) 84(1):215–25. doi: 10.1007/s10493-021-00615-5

PubMed Abstract | CrossRef Full Text | Google Scholar

29. Durães LS, Bitencourth K, Ramalho FR, Nogueira MC, Nunes EC, Gazêta GS. Biodiversity of Potential Vectors of Rickettsiae and Epidemiological Mosaic of Spotted Fever in the State of Paraná, Brazil. Front Public Health (2021) 9:577789. doi: 10.3389/fpubh.2021.577789

PubMed Abstract | CrossRef Full Text | Google Scholar

30. Montenegro DC, Bitencourth K, Oliveira SV, Borsoi ABP, Cardoso KM, Sousa MSB, et al. Spotted Fever: Epidemiology and Vector-Rickettsia-Host Relationship in Rio De Janeiro State. Front Microbiol (2017) 8:505. doi: 10.3389/fmicb.2017.00505

PubMed Abstract | CrossRef Full Text | Google Scholar

31. Pinter A, Costa CS, Holcman MM, Camara M, Leite RM. A Febre Maculosa Brasileira Na Região Metropolitana De São Paulo. BEPA (2016) 13(151):3–47.

Google Scholar

32. Vizzoni VF, Silva AB, Cardoso KM, Santos FB, Stenzel B, Amorim M, et al. 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. Acta Trop (2016) 162:142–5. doi: 10.1016/j.actatropica.2016.06.018

PubMed Abstract | CrossRef Full Text | Google Scholar

33. Krawczak FS, Munoz-Leal S, Guztazaky AC, Oliveira SV, Santos FCP, Angerami RN, et al. Rickettsia Sp. Strain Atlantic Rainforest Infection in a Patient From a Spotted Fever-Endemic Area in Southern Brazil. Am J Trop Med Hyg (2016) 95:551–3. doi: 10.4269/ajtmh.16-0192

PubMed Abstract | CrossRef Full Text | Google Scholar

34. Bitencourth K, Amorim M, Oliveira SV, Caetano RC, Voloc CM, Gazêta GS. Amblyomma Sculptum: Genetic Diversity and Rickettsias in the Brazilian Cerrado Biome. Med Vet Entomol (2017) 31:427–37. doi: 10.1111/mve.12249

PubMed Abstract | CrossRef Full Text | Google Scholar

35. Nava S, Beati L, Labruna MB, Cáceres AG, Mangold AJ, Guglielmone AA. Reassessment of the Taxonomic Status of Amblyomma Cajennense (Fabricius, 1787) With the Description of Three New Species, Amblyomma Tonelliae N. Sp., Amblyomma Interandinum N. Sp. And Amblyomma Patinoi N. Sp., and Reinstatement of Amblyomma Mixtum Koch, 1844, and Amblyomma Sculptum Berlese, 1888 (Ixodida: Ixodidae). Tick Borne Dis (2014) 5:252–76. doi: 10.1016/j.ttbdis.2013

CrossRef Full Text | Google Scholar