Epidemiology of rocky mountain spotted fever in Brazil, 2010-2020 / Epidemiologia da febre das montanhas rochosas no Brasil, 2010-2020 / Epidemiología de la fiebre de las montañas rocosas en Brasil, 2010-2020

Rocky Mountain spotted fever is a tick-borne rickettsiosis. The main clinical signs and symptoms are fever, severe headache, rashes and myalgia. It is considered difficult to diagnose and underreported. The study aims to descriptively analyze the epidemiology of cases of Rocky Mountain spotted fever in Brazil from 2010 to 2021. This is a retrospective cohort study that statisticall analyzes the cases of spotted fever in Brazil between 2010 and 2020 through data obtained by the Information System of Notifiable Diseases. The proportions of spotted fever cases were calculated according to: sex, age, race/color, infection environment and evolution. There are 1967 cases were confirmed. The regions with the most cases were the Southeast (n%=72.24) and the South (n%=24). However, there are 4 deaths in the south while the lethality coefficient from the southeast is 47.78%. The most affected age group was 40-59 years old (n%=34.87), and 20-39 years old (n%=28.98). 71.17% of the cases are male. As for color/race, 60% of the cases are in whites. As for the infection environment, 35.23% are at home, 15.3% are at work, 26.13% are leisure places. The prevalence in males and the predominant age group 20-59 years can be linked to work activity, which leaves hem more exposed to ticks. The high numbers in adulthood can also be related to ecotourism. The lethality of the disease differs between the South and Southeast regions. One explanation for this phenomenon would be the different etiological agents, R. rickettsi, predominant in the Southeast, generating more severe clinical conditions.

A febre maculosa é uma riquetsiose transmitida por carrapatos. Os principais sinais e sintomas clínicos são febre, cefaleia intensa, erupções cutâneas e mialgia. É considerada de difícil diagnóstico e subnotificada. O estudo visa analisar descritivamente a epidemiologia dos casos de febre maculosa do Brasil no período de 2010 até 2021. Trata-se de um estudo de coorte retrospectivo que analisa estatisticamente os casos de febre maculosa no Brasil entre 2010 e 2020 por meio de dados obtidos pelo Sistema de Informação de Agravos de Notificação. As proporções de casos de febre maculosa foram calculadas segundo: sexo, idade, raça/cor, ambiente de infecção e evolução. Foram confirmados 1967 casos. As regiões com mais casos foram Sudeste (n%= 72,24) e Sul (n%= 24). No entanto, há 4 óbitos no Sul enquanto o coeficiente de letalidade do Sudeste é de 47,78%. A faixa etária mais acometida foi de 40 a 59 anos (n%= 34,87) e de 20 a 39 anos (n%= 28,98). 71,17% dos casos são do sexo masculino. Quanto à cor/raça, 60% dos casos são de brancos. Quanto ao ambiente de contágio, 35,23% são em casa, 15,3% são no trabalho, 26,13% são locais de lazer. A prevalência no sexo masculino e a faixa etária predominante de 20 a 59 anos pode estar ligada à atividade laboral, que os deixa mais expostos aos carrapatos. Os altos números na idade adulta também podem estar relacionados ao ecoturismo. A letalidade da doença difere entre as regiões Sul e Sudeste, sendo que uma explicação para esse fenômeno seriam os diferentes agentes etiológicos,

La fiebre maculosa es una rickettsiosis transmitida por garrapatas. Los principales signos y síntomas clínicos son fiebre, cefalea intensa, erupciones cutáneas y mialgias. Se considera difícil de diagnosticar y poco notificada. El estudio tiene como objetivo analizar descriptivamente la epidemiología de los casos de fiebre manchada en Brasil en el período de 2010 a 2021. Se trata de un estudio de cohortes retrospectivo que analiza estadísticamente los casos de fiebre manchada en Brasil entre 2010 y 2020 a través de datos obtenidos del Sistema de Información de Agraves de Notificación. Se calcularon las proporciones de casos de fiebre manchada según: sexo, edad, raza/color, ambiente de infección y evolución. Se confirmaron 1967 casos. Las regiones con más casos fueron el Sudeste (n%= 72,24) y el Sur (n%= 24). Sin embargo, hubo 4 muertes en el Sur, mientras que el coeficiente de letalidad en el Sureste fue del 47,78%. El grupo de edad más afectado fue el de 40 a 59 años (n%= 34,87) y el de 20 a 39 años (n%= 28,98). El 71,17% de los casos eran varones. En cuanto al color/raza, el 60% de los casos son de raza blanca. En cuanto al entorno de la infección, el 35,23% se produce en el domicilio, el 15,3% en el trabajo y el 26,13% en lugares de ocio. La prevalencia en los hombres y el grupo de edad predominante de 20 a 59 años pueden estar relacionados con la actividad laboral, que los deja más expuestos a las garrapatas. El elevado número en la edad adulta también puede estar relacionado con el ecoturismo. La letalidad de la enfermedad difiere entre las regiones Sur y Sudeste, y una explicación para este fenómeno serían los diferentes agentes etiológicos, R. rickettsi, predominante en la región Sudeste, generando cuadros clínicos más severos.

Behavioral characteristics and endosymbionts of two potential tularemia and Rocky Mountain spotted fever tick vectors.

Due to climate change-induced alterations of temperature and humidity, the distribution of pathogen-carrying organisms such as ticks may shift. Tick survival is often limited by environmental factors such as dryness, but a predicted hotter and wetter world may allow the expansion of tick ranges. Dermacentor andersoni and D. variabilis ticks are morphologically similar, co-occur throughout the Inland Northwest of Washington State, U.S.A., and both can be injected with pathogenic Rickettsia and Francisella bacteria. Differences in behavior and the potential role of endosymbiotic Rickettsia and Francisella in these ticks are poorly studied. We wanted to measure behavioral and ecological differences between the two species and determine which, if any, Rickettsia and Francisella bacteria - pathogenic or endosymbiotic - they carried. Additionally, we wanted to determine if either tick species may be selected for if the climate in eastern Washington becomes wetter or dryer. We found that D. andersoni is more resistant to desiccation, but both species share similar questing behaviors such as climbing and attraction to bright light. Both also avoid the odor of eucalyptus and DEET but not permethrin. Although both tick species are capable of transmitting pathogenic species of Francisella and Rickettsia, which cause tularemia and Rocky Mountain Spotted Fever, respectively, we found primarily non-pathogenic endosymbiotic strains of Francisella and Rickettsia, and only one tick infected with F. tularensis subspecies holarctica.

In vitro acaricidal activity of different ectoparasiticide classes against Amblyomma sculptum larvae.

Zoonoses are major causes of morbidity and mortality worldwide. Among them, Brazilian Spotted Fever (BSF) is an important one that occurs in some regions of South America and can be transmitted by the "star tick" Amblyomma sculptum. Application of acaricides against the larval stage is important as strategy of population control. However, there is still a deficiency of studies on chemical control of A. sculptum and the present work aims to evaluate the in vitro acaricidal activity of cypermethrin, flumethrin, deltamethrin, fipronil, coumaphos and chlorpyrifos against A. sculptum larvae. Bioassays were performed using the larval immersion test method. A discriminatory analysis between the antiparasitic classes most used for tick control was carried out, which made it possible to determine the classes with higher potential for controlling A. sculptum larvae. Our results showed that A. sculptum larvae present highest sensitivity to the synthetic pyrethroid group, followed by the phenylpyrazole, organophosphate and macrocyclic lactone groups. These findings may support studies on improvement of tick control as in animals as in the environment.

New Jersey-Wide Survey of Spotted Fever Group Rickettsia (Proteobacteria: Rickettsiaceae) in Dermacentor variabilis and Amblyomma americanum (Acari: Ixodida: Ixodidae).

For the last decade, the New Jersey (NJ) Department of Health has reported between 42 and 144 new cases each year of "spotted fever group rickettsiosis" (SFGR), a statistic that reflects uncertainty regarding which rickettsial agents (Proteobacteria: Rickettsiaceae: Rickettsia) are infecting NJ residents. To identify the Rickettsia circulating in NJ ticks, we used a combination of conventional and real time PCR approaches to screen 560 Dermacentor variabilis Say and 245 Amblyomma americanum L. obtained from a 1-day state-wide surveillance in May 2018 and an additional 394 D. variabilis collected across NJ in 2013-2018. We found zero D. variabilis infected with Rickettsia rickettsii, the agent of Rocky Mountain spotted fever and, on average, 1.3% infected with presumed nonpathogenic Rickettsia montanensis. We also found zero A. americanum infected with R. rickettsii, and 20% infected with Rickettsia amblyommatis, a prevalence somewhat lower than in more southern states. Overall, we conclude that it is unlikely that R. rickettsii vectored by D. variabilis is a primary cause of SFGR cases in NJ and discuss our findings in the context of known facts and current limitations. We conclude that understanding the causes of SFGR east of the Mississippi will require collaboration among medical doctors, public health authorities, and medical entomologists to follow up presumptive human cases of SFGR with detailed histories of exposure, species-specific molecular assays, and active surveillance of putative vectors and the pathogens they may carry.

An exploratory analysis of demography and movement patterns of dogs: New insights in the ecology of endemic Rocky Mountain-Spotted Fever in Mexicali, Mexico.

An outbreak of Rocky Mountain spotted fever (RMSF) transmitted by the brown dog tick (Rhipicephalus sanguineus sensu lato) has emerged as a major human and animal health concern in Mexicali, Mexico. Due to high rates of brown dog tick infestation, susceptibility, and association with humans, dogs serve as sentinels and have a key role in the ecology of RMSF. A cross-sectional household questionnaire study was conducted in six rural and urban locations to characterize dog ecology and demography in RMSF high-and low-risk areas of Mexicali. In addition, we tracked movement patterns of 16 dogs using a GPS data logger. Of 253 households, 73% owned dogs, and dog ownership tended to be higher in high-risk areas, with a mean dog:human ratio of 0.43, compared with 0.3 in low-risk areas. Dogs in high-risk areas had higher fecundity and roamed more, but the dog density and numbers of free-roaming dogs were comparable. There was a higher proportion of younger dogs and lower proportion of older dogs in high-risk areas. The high proportion of immunologically naïve puppies in high risk areas could result in a lack of herd immunity leading to a more vulnerable dog and human population. The marked increase of space use of free-roaming dogs in high-risk areas suggests that unrestrained dogs could play an important role in spreading ticks and pathogens. As means to limit RMSF risk, practical changes could include increased efforts for spay-neuter and policies encouraging dog restraint to limit canine roaming and spread of ticks across communities; due to dog density is less impactful such policies may be more useful than restrictions on the number of owned dogs.

Mapping Brazilian spotted fever: Linking etiological agent, vectors, and hosts.

Brazilian spotted fever (BSF) is a highly lethal disease in southeastern Brazil. BSF is caused by the bacterium Rickettsia rickettsii and is transmitted by the bites of the tick of the genus Amblyomma. The spatial distribution of BSF risk areas is not well known in the country given the complexity of the transmission cycle. This study used the ecological niche modeling (ENM) approach to anticipate the potential distribution of the etiological agent (Rickettsia rickettsii), vectors (Amblyomma sculptum and A. dubitatum), and hosts (Hydrochoerus hydrochaeris, Didelphis aurita, and D. marsupialis) of BSF in Brazil. We compiled occurrence records for all vectors, hosts, and BSF from our own field surveillance, online repositories, and literature. ENM identified BSF risk areas in southeastern and southern Brazil, and anticipated other dispersed suitable areas in the western, central, and northeastern coast regions of Brazil. Tick vectors and mammalian hosts were confined to these same areas; however, host species showed broader suitability in northern Brazil. All species ENMs performed significantly better than random expectations. We also tested the BSF prediction based on 253 additional independent cases identified in our surveillance; the model anticipated 251 out of 253 of these independent cases. Background similarity tests comparing the ENMs of R. rickettsii, tick vectors, and mammalian hosts were unable to reject null hypotheses of niche similarity. Finally, we observed close coincidence between independent BSF cases, and areas suitable for combinations of vectors and hosts, reflecting the ability of these model pairs to anticipate the distribution of BSF cases across Brazil.

The Ability of the Invasive Asian Longhorned Tick Haemaphysalis longicornis (Acari: Ixodidae) to Acquire and Transmit Rickettsia rickettsii (Rickettsiales: Rickettsiaceae), the Agent of Rocky Mountain Spotted Fever, Under Laboratory Conditions.

The invasive Asian longhorned tick, Haemaphysalis longicornis Neumann, was first detected in the United States in 2017. It has since been found in 12 states, and there is concern that the tick's parthenogenetic ability and wide variety of host species may allow for broader dissemination. Of the tick-borne diseases endemic to the United States, Rocky Mountain spotted fever (RMSF), a rapidly progressive and potentially fatal disease caused by Rickettsia rickettsii, is the most severe. There is considerable geographical overlap between spotted fever rickettsioses cases, which include RMSF, and the currently known distribution of H. longicornis, providing the potential for this tick to encounter this pathogen. We have evaluated the ability of H. longicornis to acquire and transmit R. rickettsii under laboratory conditions. Haemaphysalis longicornis as larvae and nymphs acquired the pathogen while feeding on infected guinea pigs. The infection persisted through every life stage, all of which were able to transmit R. rickettsii to naïve hosts. The pathogen was also transmitted at a low frequency between generations of H. longicornis through the ova. While H. longicornis was demonstrated to be a competent vector for R. rickettsii under laboratory conditions, the probability of its involvement in the maintenance and transmission of this pathogen in nature, as well as its potential impact on human health, requires further study.

Needlestick-Associated Rocky Mountain Spotted Fever, Brazil.

We report a fatal case of Rocky Mountain spotted fever (RMSF) in a man in Brazil without recent history of tick bites or environmental exposure. He received an accidental needlestick while working as a nurse. The nurse and his patient died. Both cases were confirmed as RMSF by molecular methods.

Comparative analysis of the midgut microbiota of two natural tick vectors of Rickettsia rickettsii.

Although the ticks Amblyomma sculptum and Amblyomma aureolatum are important vectors of Rickettsia rickettsii, causative agent of the life-threatening Rocky Mountain spotted fever, A. aureolatum is considerably more susceptible to infection than A. sculptum. As the microbiota can interfere with the colonization of arthropod midgut (MG) by pathogens, in the current study we analyzed the MG microbiota of both tick species. Our results revealed that the MG of A. aureolatum harbors a prominent microbiota, while A. sculptum does not. Remarkably, a significant reduction of the bacterial load was recorded in R. rickettsii-infected A. aureolatum. In addition, the taxonomy analysis of the MG bacterial community of A. aureolatum revealed a dominance of the genus Francisella, suggesting an endosymbiosis. This study is the first step in getting insights into the mechanisms underlying the interactions among Amblyomma species, their microbiota and R. rickettsii. Additional studies to better understand these mechanisms are required and may help the development of novel alternatives to block rickettsial transmission.

Minimal Duration of Tick Attachment Sufficient for Transmission of Infectious Rickettsia rickettsii (Rickettsiales: Rickettsiaceae) by Its Primary Vector Dermacentor variabilis (Acari: Ixodidae): Duration of Rickettsial Reactivation in the Vector Revisited.

It has been reported that starving ticks do not transmit spotted fever group Rickettsia immediately upon attachment because pathogenic bacteria exist in a dormant, uninfectious state and require time for 'reactivation' before transmission to a susceptible host. To clarify the length of reactivation period, we exposed guinea pigs to bites of Rickettsia rickettsii-infected Dermacentor variabilis (Say) and allowed ticks to remain attached for predetermined time periods from 0 to 48 h. Following removal of attached ticks, salivary glands were immediately tested by PCR, while guinea pigs were observed for 10-12 d post-exposure. Guinea pigs in a control group were subcutaneously inoculated with salivary glands from unfed D. variabilis from the same cohort. In a parallel experiment, skin at the location of tick bite was also excised at the time of tick removal to ascertain dissemination of pathogen from the inoculation site. Animals in every exposure group developed clinical and pathological signs of infection. The severity of rickettsial infection in animals increased with the length of tick attachment, but even attachments for less than 8 h resulted in clinically identifiable infection in some guinea pigs. Guinea pigs inoculated with salivary glands from unfed ticks also became severely ill. Results of our study indicate that R. rickettsii residing in salivary glands of unfed questing ticks does not necessarily require a period of reactivation to precede the salivary transmission and ticks can transmit infectious Rickettsia virtually as soon as they attach to the host.

In vitro acaricidal activity of different ectoparasiticide classes against Amblyomma sculptum larvae / Atividade acaricida in vitro de diferentes classes de ectoparasiticidas frente a larvas de Amblyomma sculptum

Abstract Zoonoses are major causes of morbidity and mortality worldwide. Among them, Brazilian Spotted Fever (BSF) is an important one that occurs in some regions of South America and can be transmitted by the "star tick" Amblyomma sculptum. Application of acaricides against the larval stage is important as strategy of population control. However, there is still a deficiency of studies on chemical control of A. sculptum and the present work aims to evaluate the in vitro acaricidal activity of cypermethrin, flumethrin, deltamethrin, fipronil, coumaphos and chlorpyrifos against A. sculptum larvae. Bioassays were performed using the larval immersion test method. A discriminatory analysis between the antiparasitic classes most used for tick control was carried out, which made it possible to determine the classes with higher potential for controlling A. sculptum larvae. Our results showed that A. sculptum larvae present highest sensitivity to the synthetic pyrethroid group, followed by the phenylpyrazole, organophosphate and macrocyclic lactone groups. These findings may support studies on improvement of tick control as in animals as in the environment.

Resumo As zoonoses são a maior causa de morbidade de mortalidade no mundo. A Febre Maculosa Brasileira (FMB) é uma importante zoonose que ocorre em algumas regiões da América do Sul e pode ser transmitida pelo "carrapato-estrela" Amblyomma sculptum. A aplicação de acaricidas, frente ao estágio larval, é importante como estratégia no controle da população. No entanto, ainda há uma deficiência de estudos para o controle químico de A. sculptum. Devido à necessidade de mais informações sobre o controle de A. sculptum, o presente trabalho tem como objetivo avaliar a atividade acaricida in vitro de cipermetrina, flumetrina, deltametrina, fipronil, coumafós e clorpirifós frente a larvas de A. sculptum. Os bioensaios foram realizados pelo método Teste de Imersão de Larva. Foi realizada uma análise discriminatória entre as classes antiparasitárias mais utilizadas para controle de carrapatos, possibilitando determinar classes com maior potencial para o controle de larvas de A. sculptum. Os resultados deste trabalho mostraram que as larvas de A. sculptum apresentam maior sensibilidade ao grupo dos piretroides sintéticos, seguido pelos grupos fenilpirazóis, organofosforados e lactonas macrocíclicas. Esses achados poderiam apoiar estudos visando ao controle do carrapato tanto em animais quanto no meio ambiente.

Integrated tick control on a farm with the presence of capybaras in a Brazilian spotted fever endemic region.

Ticks of the Amblyomma cajennense complex present high infestation rates. These ticks transmit the bacterium Rickettsia rickettsii, which causes Brazilian Spotted Fever. For this reason, an integrated tick control system was adopted on a farm in the municipality of Itu, state of São Paulo. On this farm, which borders the Tietê river, domestic animals are in contact with populations of capybaras. Six locations were monitored and evaluated between the years of 2015 and 2017. During this work 1271 nymphs and adult ticks were caught, all of them from the Amblyomma sculptum species, except for a single individual from the Amblyomma dubitatum species. The integrated tick management reduced the overall infestation levels to zero. Adult tick population dropped in the first year of the study, while larvae population dropped in the second year. Nymph population dropped in both years, decreasing in higher numbers in the first year. The estimated mean infestation levels for all of the tick's life cycle forms in the six monitored spots did not reach one individual in the end of the study. Estimated mean infestation levels for nymphs in these places equaled zero.

Integrated tick control on a farm with the presence of capybaras in a Brazilian spotted fever endemic region / Controle integrado do carrapato em uma fazenda com presença de capivaras em região endêmica para febre maculosa brasileira

Abstract Ticks of the Amblyomma cajennense complex present high infestation rates. These ticks transmit the bacterium Rickettsia rickettsii, which causes Brazilian Spotted Fever. For this reason, an integrated tick control system was adopted on a farm in the municipality of Itu, state of São Paulo. On this farm, which borders the Tietê river, domestic animals are in contact with populations of capybaras. Six locations were monitored and evaluated between the years of 2015 and 2017. During this work 1271 nymphs and adult ticks were caught, all of them from the Amblyomma sculptum species, except for a single individual from the Amblyomma dubitatum species. The integrated tick management reduced the overall infestation levels to zero. Adult tick population dropped in the first year of the study, while larvae population dropped in the second year. Nymph population dropped in both years, decreasing in higher numbers in the first year. The estimated mean infestation levels for all of the tick's life cycle forms in the six monitored spots did not reach one individual in the end of the study. Estimated mean infestation levels for nymphs in these places equaled zero.

Resumo Em virtude de alta infestação por carrapatos do complexo Amblyomma cajennense, parasitos que transmitem a bactéria Rickettsia rickettsii, causadora da Febre Maculosa Brasileira, adotou-se um sistema de controle integrado dos carrapatos numa propriedade rural localizada no munícipio de Itu - SP. Na propriedade, que margeia o rio Tietê, os animais domésticos mantinham contato com populações de capivaras. Seis locais foram avaliados e monitorados nos anos de 2015 a 2017. Dentre os 1271 espécimes capturados (adultos e ninfas) um foi identificado como Amblyomma dubitatum e os demais com Amblyomma sculptum. De um modo geral, houve controle da infestação de carrapatos visto que todos os estágios ao final de 2017 apresentaram níveis próximos ou igual a zero. A população de adultos teve queda no primeiro ano e a de larvas no segundo. As ninfas apresentaram queda nos dois anos, sendo mais acentuada no primeiro ano. A média da estimativa do nível de infestação para cada estágio do carrapato nos seis locais monitorados não chegou a 1 indivíduo ao final do experimento, sendo que a média da estimativa para as ninfas foi de zero em todos esses locais.

Serosurvey of Rickettsia spp. in cats from a Brazilian spotted fever-endemic area / Soroprevalência de Rickettsia spp. em gatos de uma área endêmica para a Febre Maculosa Brasileira

Abstract Rickettsia spp. bacteria are responsible for tick-borne diseases worldwide, mostly maintained by rickettsial amplifiers capybaras in Brazilian endemic areas. The campus of the University of São Paulo, in southeastern Brazil, is an area endemic for Brazilian spotted fever (BSF), with high density of capybaras and Amblyomma spp., along with confirmed human cases. Besides capybaras, the university has also an in-campus high population of sheltered and free-roaming cats. Accordingly, the aim of this study was to determine the prevalence and characteristics associated with Rickettsia rickettsii, Rickettsia parkeri and Rickettsia felis exposure among cats in a BSF-endemic area. Out of 51 cats sampled, 23/35 shelter (65.7%) and 5/16 free-roaming (31.2%) were positive (titers ≥ 64) for at least one Rickettsia species. Ticks species were present in 3/16 free-roaming cats (18.8%), consisting of Amblyomma spp., nymphs of Amblyomma sculptum and adult Rhipicephalus sanguineus sensu lato. Despite sharing the capybaras environment, the seropositivity among the free-roaming and shelter cats was lower than owned cats in other endemic areas. Whether equally or less exposed to rickettsial infection, compared with owned cats in endemic areas, free-roaming and shelter cats may be used as environmental sentinels for human exposure to rickettsiae in such areas.

Resumo Espécies de Rickettsia têm sido responsáveis por doenças transmitidas por carrapatos no mundo, a maioria mantida por hospedeiros amplificadores, como as capivaras em áreas endêmicas no Brasil. A Universidade de São Paulo, em Piracicaba, no sudeste do Brasil, é uma área endêmica para a Febre Maculosa Brasileira (FMB), com alta densidade de capivaras e Amblyomma spp., e com casos humanos confirmados. Além de capivaras, a universidade também possui gatos em um abrigo e de vida livre. Assim, o objetivo deste estudo foi determinar a prevalência e as características associadas com exposição à Rickettsia rickettsii, Rickettsia parkeri e Rickettsia felis em gatos de área endêmica para a FMB. Dos 51 gatos amostrados, 23/35 (65,7%) do abrigo e 5/16 (31,2%) de vida livre foram positivos (títulos ≥ 64) para pelo menos uma Rickettsia spp. Carrapatos estiveram presentes em 3/16 (18,8%) gatos de vida livre, representados por Amblyomma spp., ninfas de Amblyomma sculptum e adultos de Rhipicephalus sanguineus sensu lato. Apesar de compartilharem o ambiente com capivaras, os gatos amostrados foram igualmente ou menos expostos à infecção riquetsial do que os gatos com proprietário em outras áreas endêmicas, podendo ser usados como sentinelas para exposição humana à riquétsias nessas áreas.

Fatal Brazilian Spotted Fever Associated with Dogs and Amblyomma aureolatum Ticks, Brazil, 2013.

In São Paulo metropolitan area, Brazil, Amblyomma aureolatum ticks are the main vector of Rickettsia rickettsii, which causes Brazilian spotted fever. In 2013, a boy in São Paulo died of Brazilian spotted fever associated with household dogs and A. aureolatum ticks. Prompt recognition and treatment of this illness might prevent deaths.

Serosurvey of Rickettsia spp. in cats from a Brazilian spotted fever-endemic area.

Rickettsia spp. bacteria are responsible for tick-borne diseases worldwide, mostly maintained by rickettsial amplifiers capybaras in Brazilian endemic areas. The campus of the University of São Paulo, in southeastern Brazil, is an area endemic for Brazilian spotted fever (BSF), with high density of capybaras and Amblyomma spp., along with confirmed human cases. Besides capybaras, the university has also an in-campus high population of sheltered and free-roaming cats. Accordingly, the aim of this study was to determine the prevalence and characteristics associated with Rickettsia rickettsii, Rickettsia parkeri and Rickettsia felis exposure among cats in a BSF-endemic area. Out of 51 cats sampled, 23/35 shelter (65.7%) and 5/16 free-roaming (31.2%) were positive (titers ≥ 64) for at least one Rickettsia species. Ticks species were present in 3/16 free-roaming cats (18.8%), consisting of Amblyomma spp., nymphs of Amblyomma sculptum and adult Rhipicephalus sanguineus sensu lato. Despite sharing the capybaras environment, the seropositivity among the free-roaming and shelter cats was lower than owned cats in other endemic areas. Whether equally or less exposed to rickettsial infection, compared with owned cats in endemic areas, free-roaming and shelter cats may be used as environmental sentinels for human exposure to rickettsiae in such areas.

Brazilian Spotted Fever Prevention through a Nonlethal Capybara Population Control Strategy.

INTRODUCTION: Brazilian spotted fever (BSF), a lethal tick-borne Rickettsioses (2000 - 2018 >600 human deaths) involving synanthropic capybara as host. METHODS: We introduced an alternative to mitigate human-capybara conflicts and epidemiologic concerns of BSF. Complex aspects like transmission dynamics, risk areas, host mobility, and birth rate control, were considered to develop a prevention strategy using an anti-GnRH vaccine. RESULTS: The propositioned immunocontraceptive potentially remove and prevent the spread of BSF from endemic areas. CONCLUSIONS: We propose the anti-GnRH vaccine as a BSF prevention strategy based on these favorable results.

A Cluster of Cases of Rocky Mountain Spotted Fever in an Area Of Colombia Not Known to be Endemic for This Disease.

Rocky Mountain spotted fever (RMSF) has been reported in Colombia since 1937. Most recent outbreaks were in 2006-2008, followed by the absence of recognized cases. This report describes new clinical cases of RMSF and epidemiologic investigations. Medical records were reviewed, and fieldwork, serological and molecular diagnostic testing, and bacterial isolation were performed. Fever, hypotension, abdominal discomfort, and rash accompanied by thrombocytopenia and leukopenia were the most characteristic manifestations. Two convalescent sera from the index case and sera from two dogs revealed high anti-spotted fever group Rickettsia antibody titers. Rickettsia rickettsii was isolated from case 4. Cases 2 and 3 were identified by epidemiological connection with the index case. Thus, a new cluster of cases of RMSF was identified in Antioquia, Colombia, with the occurrence of fatal cases, which indicates the active circulation of the bacteria and a potential risk for the population.