Tick-borne Apicomplexa in wildlife and ticks of French Guiana.

Tick-borne Apicomplexa encompass a group of parasites responsible for significant medical and veterinary diseases, including babesiosis, theileriosis, and hepatozoonosis. In this study, we investigated the presence and diversity of tick-borne Apicomplexa in wildlife and ticks inhabiting the Amazon rainforests of French Guiana. To this end, we conducted molecular screening and typing using 18S rRNA sequences on a collection of 1161 specimens belonging to 71 species, including 44 species of wild mammals, five species of passerines, and 22 species of ticks. We characterized eight genovariants of Babesia, Theileria, Hemolivia, and Hepatozoon parasites, some matching known species, while others suggested potential novel species. These parasites were detected in wild mammals, including opossums, sloths, armadillos, porcupines, margays, greater grisons, and ticks, but not in passerines. Finally, similarities with surveys conducted in Brazil highlight the specific sylvatic transmission cycles of South American tick-borne Apicomplexa.

Title: Apicomplexes transmis par les tiques chez la faune sauvage et les tiques de Guyane française. Abstract: Les Apicomplexes transmis par les tiques englobent un groupe de parasites responsables de maladies médicales et vétérinaires importantes, notamment la babésiose, la theilériose et l'hépatozoonose. Dans cette étude, nous avons étudié la présence et la diversité des Apicomplexes transmis par les tiques dans la faune sauvage et les tiques habitant les forêts tropicales amazoniennes de Guyane française. À cette fin, nous avons effectué un criblage moléculaire et un typage à l'aide de séquences d'ARNr 18S sur une collection de 1 161 spécimens appartenant à 71 espèces, dont 44 espèces de mammifères sauvages, cinq espèces de passereaux et 22 espèces de tiques. Nous avons caractérisé huit génovariants des parasites Babesia, Theileria, Hemolivia et Hepatozoon, certains correspondant à des espèces connues tandis que d'autres suggéraient de nouvelles espèces potentielles. Ces parasites ont été détectés chez des mammifères sauvages, dont des opossums, des paresseux, des tatous, des porcs-épics, des margays, des grisons et des tiques, mais pas chez des passereaux. Enfin, des similitudes avec des enquêtes menées au Brésil mettent en évidence les cycles de transmission sylvatiques spécifiques des Apicomplexa transmis par les tiques d'Amérique du Sud.

Pathogens associated with ticks (Acari: Ixodidae) and mammals in the Orinoquia region of Colombia: An approach to understanding vector-pathogen-host interactions.

The hard tick clade (Ixodidae) currently comprises 762 species worldwide (266 Prostriata and 496 Metastriata). A quarter of hard ticks are found in the Neotropical region, and 42 species have been documented in Colombia. Ixodidae species are important vectors of pathogens such as bacteria, helminths, protozoa, and viruses. In tick-borne diseases, vertebrate hosts perform an important role in the transmission, maintenance, and spread of pathogens. Colombia ranks sixth among countries with the highest mammal biodiversity, with a total of 548 species, where some of these species may be involved in pathogen transmission cycles with ticks as vectors. This research evaluated the presence of two genera of bacteria (Borrelia and Rickettsia) and the protozoan (Babesia) in ticks and mammals in the Orinoquia region of Colombia, establishing interaction networks. The information comes from 734 mammals (655 wild and 79 domestic), belonging to 59 species. Tick infestation (n = 1,805) was found with 14.85 % (n = 109) of the examined mammals and corresponds to nine tick species confirmed morphologically and molecularly. To detect pathogens 272 ticks were collected while feeding on 96 mammals; samples from 93 mammals were analyzed. The presence of borreliae from the relapsing fever group (RFG) and the Lyme disease group (LDG) were detected. Rickettsia spp. was detected in ticks and mammals, while Babesia bigemina was only detected in ticks. This research is the first to address the prevalence of zoonotic pathogens in domestic and wild mammals infested with hard ticks in the Department of Arauca, Colombia. Considering that reporting cases of infections with Babesia, Borrelia, and Rickettsia in Colombia is not mandatory, their impact on public health cannot be estimated. This highlights the importance of continuously detecting, confirming, and identifying these and other important pathogens within the "One Health" framework, as they have a significant economic and medical-veterinary impact globally.

Experimental infection and vector competence of Amblyomma patinoi, a member of the Amblyomma cajennense species complex, for the human pathogen Rickettsia rickettsii.

Amblyomma patinoi ticks infected with Rickettsia rickettsii are present in Colombia, but its vector competence is unknown. Hence, we evaluated the vector competence of A. patinoi with R. rickettsii under laboratory conditions. Experimental guinea pigs and rabbits (males and females) were separated in the infected group (IG) and the control group (CG). In the IG, the filial 1 (F1) larvae (R. rickettsii-free) from Colombian A. patinoi engorged female specimens were exposed to R. rickettsii (ITU strain) by feeding on infected guinea pigs. Next, F1 nymphs and adults, and F2 larvae were allowed to feed on uninfected guinea pigs or rabbits and tested by qPCR targeting the gltA rickettsial gene. All animals used to feed the IG F1 ticks became febrile and had R. rickettsii infection (89% fatality rate) detected through serological or molecular techniques. After the F1 larvae ticks became R. rickettsii infected, subsequent IG tick stages were able to maintain the rickettsial infection by transstadial maintenance to all infested animals, indicating A. patinoi vector competence. Subsequently, almost 31% of the F1 female egg masses and only 42% of their F2 larvae were infected. Less than 50% of the infected females transmitted R. rickettsii transovarially, and only a part of the offspring were infected. This study demonstrated that A. patinoi might not be able to sustain R. rickettsii infection by transovarial transmission for successive tick generations without horizontal transmission via rickettsemic hosts. This condition might result in low R. rickettsii-infection rates of A. patinoi under natural conditions.

Tick Immune System: What Is Known, the Interconnections, the Gaps, and the Challenges.

Ticks are ectoparasitic arthropods that necessarily feed on the blood of their vertebrate hosts. The success of blood acquisition depends on the pharmacological properties of tick saliva, which is injected into the host during tick feeding. Saliva is also used as a vehicle by several types of pathogens to be transmitted to the host, making ticks versatile vectors of several diseases for humans and other animals. When a tick feeds on an infected host, the pathogen reaches the gut of the tick and must migrate to its salivary glands via hemolymph to be successfully transmitted to a subsequent host during the next stage of feeding. In addition, some pathogens can colonize the ovaries of the tick and be transovarially transmitted to progeny. The tick immune system, as well as the immune system of other invertebrates, is more rudimentary than the immune system of vertebrates, presenting only innate immune responses. Although simpler, the large number of tick species evidences the efficiency of their immune system. The factors of their immune system act in each tick organ that interacts with pathogens; therefore, these factors are potential targets for the development of new strategies for the control of ticks and tick-borne diseases. The objective of this review is to present the prevailing knowledge on the tick immune system and to discuss the challenges of studying tick immunity, especially regarding the gaps and interconnections. To this end, we use a comparative approach of the tick immune system with the immune system of other invertebrates, focusing on various components of humoral and cellular immunity, such as signaling pathways, antimicrobial peptides, redox metabolism, complement-like molecules and regulated cell death. In addition, the role of tick microbiota in vector competence is also discussed.

Benefits and Drawbacks of Citizen Science to Complement Traditional Data Gathering Approaches for Medically Important Hard Ticks (Acari: Ixodidae) in the United States.

Tick-borne diseases are increasing in North America. Knowledge of which tick species and associated human pathogens are present locally can inform the public and medical community about the acarological risk for tick bites and tick-borne infections. Citizen science (also called community-based monitoring, volunteer monitoring, or participatory science) is emerging as a potential approach to complement traditional tick record data gathering where all aspects of the work is done by researchers or public health professionals. One key question is how citizen science can best be used to generate high-quality data to fill knowledge gaps that are difficult to address using traditional data gathering approaches. Citizen science is particularly useful to generate information on human-tick encounters and may also contribute to geographical tick records to help define species distributions across large areas. Previous citizen science projects have utilized three distinct tick record data gathering methods including submission of: 1) physical tick specimens for identification by professional entomologists, 2) digital images of ticks for identification by professional entomologists, and 3) data where the tick species and life stage were identified by the citizen scientist. We explore the benefits and drawbacks of citizen science, relative to the traditional scientific approach, to generate data on tick records, with special emphasis on data quality for species identification and tick encounter locations. We recognize the value of citizen science to tick research but caution that the generated information must be interpreted cautiously with data quality limitations firmly in mind to avoid misleading conclusions.

[Lymphadenopathy transmitted by tick. A pediatric case of rickettsiosis in primary care]. / Linfadenopatía transmitida por garrapata. Un caso pediátrico de rickettsiosis en atención primaria.

The entity called tick-borne lymphadenopathy, also known as dermacentor-borne necrosis eritema lymphadenopathy, is included in the differential diagnosis of diseases transmitted by ticks, which have increased considerably in recent years due to greater clinical-epidemiological observation and diagnostic improvement. It is a zoonosis caused by Rickettsia slovaca and transmitted by the bite of the Dermacentor marginatus tick. Affected patients have a necrotic eschar surrounded by an erythematous halo in the scalp, as well as painful regional lymphadenopathy. We present a seven-year-old male who shows, after the extraction of a tick, a necrotic eschar on the scalp, accompanied by lymphadenopathy and low-grade fever. The study of polymerase chain reaction and culture of the lesion confirm the presence of Rickettsia slovaca. The patient received oral azithromycin with a good response. In Primary Care, it is important to monitor the tick bites, to detect possible diseases transmitted by them.

La entidad llamada tick-borne lymphadenopathy, también conocida como dermacentor-borne necrosis eritema lymphadenopathy, se incluye dentro del diagnóstico diferencial de enfermedades transmitidas por garrapatas, que han aumentado considerablemente en los últimos años debido a una mayor observación clínica-epidemiológica y mejoría diagnóstica. Es una zoonosis causada por Rickettsia slovaca y transmitida por la picadura de la garrapata Dermacentor marginatus. Los pacientes afectados tienen una escara necrótica rodeada de un halo eritematoso en el cuero cabelludo y adenopatías regionales dolorosas. Se presenta a un varón de siete años que mostró, tras la extracción de una garrapata, una escara necrótica en el cuero cabelludo, con adenopatías y febrícula. La reacción en cadena de la polimerasa y el cultivo de la lesión confirmaron la presencia de Rickettsia slovaca. El paciente recibió azitromicina oral con buena respuesta. En Atención Primaria, es importante el seguimiento de las picaduras de garrapatas para detectar posibles enfermedades transmitidas por estas.

Phylogenetic divergence between Rickettsia amblyommatis strains from Argentina.

The aim of this study was to investigate if there is a phylogenetic divergence of Rickettsia amblyommatis strains from different phytogeographic provinces of Argentina and South America. Therefore, ompA and ompB gene sequences of R. amblyommatis DNA detected in Amblyomma hadanii and Amblyomma neumanni ticks from the Yungas and Chaco phytogeographic provinces, respectively, were obtained. These sequences were compared with GenBank sequences from R. amblyommatis from different countries of the American continent. The analyses shown that ompA haplotypes of R. amblyommatis form two clusters which differ phylogenetically. Regarding to ompB sequences, three groups of R. amblyommatis strains were detected. It could be shown that strains of R. amblyommatis detected in A. hadanii from the phytogeographic province Yungas are phylogenetic different to them detected in A. neumanni from the phytogeographic province Chaco. Furthermore, it could be observed that strains detected in different tick species associated with different phytogeographic provinces of the American continent differ phylogenetically.

Occupational risk for personnel working in veterinary clinics through exposure to vectors of rickettsial pathogens.

Workers at veterinary clinics are exposed to zoonotic pathogens, which, though infrequently, can lead to serious consequences. The aim of the present study was to estimate the seroprevalence for rickettsial pathogens in veterinary clinic personnel in Ciudad Juárez, Chihuahua, Mexico. Voluntary participants included 106 veterinarians, 19 pet groomers, 36 veterinary assistants and 6 administrative workers who supplied blood samples taken by venipuncture. Detection of Rickettsia rickettsii, Ehrlichia spp. and Anaplasma phagocytophilum was conducted by indirect immunofluorescence assay (IFA) and polymerase chain reaction (PCR) techniques. To determine risk factors for the seroprevalence, the study considered social, demographic and occupational variables as well as the clinical signs and symptoms of the participants. Logistic regression procedures were performed, and the odds ratio (OR) was calculated with confidence intervals corresponding to a probability of 95%. The results indicate that 54% of the participants had a positive seroreaction to at least one of the pathogens evaluated and 2% were positive to all. The coexposure was as follows: 3% to R. rickettsii and A. phagocytophilum, 9% to Ehrlichia spp. and A. phagocytophilum, and 2% to Ehrlichia spp. and R. rickettsii. It was established that grooming posed the highest risk for R. rickettsii exposure. The implementation of appropriate management practices for zoonotic diseases is recommended to avoid health problems that may be life threatening to personnel in veterinary clinics.

Passage of Borrelia burgdorferi through diverse Ixodid hard ticks causes distinct diseases: Lyme borreliosis and Baggio-Yoshinari syndrome.

Baggio-Yoshinari syndrome is an emerging, tick-borne, infectious disease recently discovered in Brazil. This syndrome is similar to Lyme disease, which is common in the United States of America, Europe and Asia; however, Brazilian borreliosis diverges from the disease observed in the Northern Hemisphere in its epidemiological, microbiological, laboratory and clinical characteristics. Polymerase chain reaction procedures showed that Baggio-Yoshinari syndrome is caused by the Borrelia burgdorferi sensu stricto spirochete. This bacterium has not yet been isolated or cultured in adequate culture media. In Brazil, this zoonosis is transmitted to humans through the bite of Amblyomma and Rhipicephalus genera ticks; these vectors do not belong to the usual Lyme disease transmitters, which are members of the Ixodes ricinus complex. The adaptation of Borrelia burgdorferi to Brazilian vectors and reservoirs probably originated from spirochetes with atypical morphologies (cysts or cell-wall-deficient bacteria) exhibiting genetic adjustments, such as gene suppression. These particularities could explain the protracted survival of these bacteria in hosts, beyond the induction of a weak immune response and the emergence of serious reactive symptoms. The aim of the present report is to note differences between Baggio-Yoshinari syndrome and Lyme disease, to help health professionals recognize this exotic and neglected zoonosis.

Molecular detection of the human pathogen Rickettsia parkeri strain Atlantic rainforest in Amblyomma ovale ticks in Argentina.

Human rickettsioses caused by Rickettsia parkeri strain Atlantic rainforest in Brazil motivated the analysis of Amblyomma ovale ticks in Misiones province, a similar ecological region in northeastern Argentina. During 2010-2017, 393 A. ovale ticks were collected from domestic and wild animals and from vegetation, and 177 were pooled for rickettsial detection by PCR targeting the gltA, ompA and ompB genes. A sample consisting of a pool of two A. ovale adults collected on Nasua nasua was positive for Rickettsia parkeri strain Atlantic rainforest. Since the Atlantic rainforest areas in Brazil share environmental characteristics with Misiones province, the transmission cycle of R. parkeri strain Atlantic rainforest observed in Brazil should be extrapolated to Argentina, where awareness on the possibility of occurrence of rickettsiosis cases caused by this strain should be raised.

Surveillance for Tick-Borne Viruses Near the Location of a Fatal Human Case of Bourbon Virus (Family Orthomyxoviridae: Genus Thogotovirus) in Eastern Kansas, 2015.

Bourbon virus (Family Orthomyxoviridae: Genus Thogotovirus) was first isolated from a human case-patient residing in Bourbon County, Kansas, who subsequently died. Before becoming ill in late spring of 2014, the patient reported several tick bites. In response, we initiated tick surveillance in Bourbon County and adjacent southern Linn County during spring and summer of 2015. We collected 20,639 host-seeking ticks representing four species from 12 sites. Amblyomma americanum (L.) (Acari: Ixodidae) and Dermacentor variabilis (Say) (Acari: Ixodidae) accounted for nearly all ticks collected (99.99%). Three tick pools, all composed of adult A. americanum ticks collected in Bourbon County, were virus positive. Two pools were Heartland virus (Family Bunyaviridae: Genus Phlebovirus) positive, and one was Bourbon virus positive. The Bourbon virus positive tick pool was composed of five adult females collected on a private recreational property on June 5. Detection of Bourbon virus in the abundant and aggressive human-biting tick A. americanum in Bourbon County supports the contention that A. americanum is a vector of Bourbon virus to humans. The current data combined with virus detections in Missouri suggest that Bourbon virus is transmitted to humans by A. americanum ticks, including both the nymphal and adult stages, that ticks of this species become infected as either larvae, nymphs or both, perhaps by feeding on viremic vertebrate hosts, by cofeeding with infected ticks, or both, and that Bourbon virus is transstadially transmitted. Multiple detections of Heartland virus and Bourbon virus in A. americanum ticks suggest that these viruses share important components of their transmission cycles.

Rickettsia parkeri in free-ranging wild canids from Brazilian Pampa.

Spotted fevers are tick-borne diseases associated with various Rickettsia species. Rickettsia parkeri sensu stricto (s.s.) is the agent of an emerging eschar-associated rickettsiosis in humans from the USA and South American Pampa. Considering that R. parkeri s.s. is restricted to Americas and the potential role of dogs in the epidemiology of the disease, it is thus reasonable to hypothesize that wild canids could be involved in the enzootic cycle of this rickettsiosis. The aim of this work was to investigate the potential role of the wild canids from Pampa, Cerdocyon thous (crab-eating fox) and Lycalopex gymnocercus (Pampas fox), in the ecology of R. parkeri s.s. For that, 32 live-trapped free-ranging wild canids were sampled. Ticks were observed in 30 of the 32 foxes. Of the 292 ticks collected, 22 (7.5%) were positive by PCR for the presence of R. parkeri s.s. DNA. Also, 20 (62%) wild canids showed antibodies against R. parkeri. The results suggest that wild canids are involved in the enzootic cycle of R. parkeri s.s. in the Pampa biome and could be responsible for pathogen (and its vectors) dispersal.

Passage of Borrelia burgdorferi through diverse Ixodid hard ticks causes distinct diseases: Lyme borreliosis and Baggio-Yoshinari syndrome

Baggio-Yoshinari syndrome is an emerging, tick-borne, infectious disease recently discovered in Brazil. This syndrome is similar to Lyme disease, which is common in the United States of America, Europe and Asia; however, Brazilian borreliosis diverges from the disease observed in the Northern Hemisphere in its epidemiological, microbiological, laboratory and clinical characteristics. Polymerase chain reaction procedures showed that Baggio-Yoshinari syndrome is caused by the Borrelia burgdorferi sensu stricto spirochete. This bacterium has not yet been isolated or cultured in adequate culture media. In Brazil, this zoonosis is transmitted to humans through the bite of Amblyomma and Rhipicephalus genera ticks; these vectors do not belong to the usual Lyme disease transmitters, which are members of the Ixodes ricinus complex. The adaptation of Borrelia burgdorferi to Brazilian vectors and reservoirs probably originated from spirochetes with atypical morphologies (cysts or cell-wall-deficient bacteria) exhibiting genetic adjustments, such as gene suppression. These particularities could explain the protracted survival of these bacteria in hosts, beyond the induction of a weak immune response and the emergence of serious reactive symptoms. The aim of the present report is to note differences between Baggio-Yoshinari syndrome and Lyme disease, to help health professionals recognize this exotic and neglected zoonosis.

Comparative evaluation of Amblyomma ovale ticks infected and noninfected by Rickettsia sp. strain Atlantic rainforest, the agent of an emerging rickettsiosis in Brazil.

In 2010, a novel spotted fever group rickettsiosis was reported in the Atlantic rainforest coast of Brazil. The etiological agent was identified as Rickettsia sp. strain Atlantic rainforest, and the tick Amblyomma ovale was incriminated as the presumed vector. The present study evaluated under laboratory conditions four colonies of A. ovale: two started from engorged females that were naturally infected by Rickettsia sp. strain Atlantic rainforest (designated as infected groups); the two others started from noninfected females (designated as control groups). All colonies were reared in parallel from F0 engorged female to F2 unfed nymphs. Tick-naïve vesper mice (Calomys callosus) or domestic rabbits were used for feeding of each tick stage. Rickettsia sp. strain Atlantic rainforest was preserved by transstadial maintenance and transovarial transmission in A. ovale ticks for at least 2 generations (from F0 females to F2 nymphs), because nearly 100% of the tested larvae, nymphs, and adults from the infected groups were shown by PCR to contain rickettsial DNA. All vesper mice and rabbits infested by larvae and nymphs, and 50% of the rabbits infested by adults from the infected groups seroconverted, indicating that these tick stages were vector competent for Rickettsia sp. strain Atlantic rainforest. Expressive differences in mortality rates and reproductive performance were observed between engorged females from the infected and control groups, as indicated by 75.0% and 97.1% oviposition success, respectively, and significantly lower egg mass weight, conversion efficiency index, and percentage of egg hatching for the infected groups. Our results indicate that A. ovale can act as a natural reservoir for Rickettsia sp. strain Atlantic rainforest. However, due to deleterious effect caused by this rickettsial agent on engorged females, amplifier vertebrate hosts might be necessary for persistent perpetuation of Rickettsia sp. strain Atlantic rainforest in A. ovale under natural conditions.

Transplacental transmission of bovine tick-borne pathogens: Frequency, co-infections and fatal neonatal anaplasmosis in a region of enzootic stability in the northeast of Brazil.

Bovine tick-borne disease (TBD) constitutes a worldwide group of diseases that result in great losses for dairy and beef cattle. With regard to the epidemiological profile of the diseases, the importance of transplacental transmission is still not very well understood. The aim of this study was to determine the transplacental transmission of TBD agents (Anaplasma marginale, Babesia bovis and B. bigemina) in a herd of dairy cattle that had been naturally infected in an area of enzootic stability in northeastern Brazil. Blood for serology of the three agents was collected from cows within 120 days of gestation and serology, haemogram and nPCR assays were performed after birth. Blood was collected from the calves within 3h of birth, and haemogram and nPCR assays were performed in all animals. Pre-colostrum serology was achieved in 34 animals. The Student's t-test was used to compare the haemogram results between animals that were positive and negative for the haemoparasites. The cows were seropositive for all agents in at least one of the examinations. We detected 15 cases of vertical transmission of A. marginale, 4 of B. bovis and 2 of B. bigemina in the 60 cows. In infected animals, co-infection was detected for A. marginale and B. bovis in 1 of 60 calves, and a triple infection was detected in one other calf. Fatal neonatal anaplasmosis was observed in 1 of 15 calves, in which death occurred within 24h of birth. From the results, we concluded that transplacental transmission of TBD agents occurs, including in cases of co- and triple-infection. Such transplacental transmission can cause neonatal death, increasing the importance of this form of epidemiological transmission and suggesting its role as a cause of undiagnosed neonatal death.

Spotted fever group Rickettsia in Amblyomma dubitatum tick from the urban area of Campo Grande, Mato Grosso do Sul, Brazil.

Rickettsia infection of each tick was evaluated by the hemolymph test and polymerase chain reaction (PCR) targeting gltA and ompA genes. All hemolymph tests were negative and PCR of one A. dubitatum detected both Rickettsia genes. Sequence of ompA exhibited a 99% identity with Rickettsia parkeri and R. africae and a 98% identity with R. sibirica. Rickettsia of the spotted fever group in A. dubitatum is described for the first time in an urban area within the municipality of Campo Grande in the state of Mato Grosso do Sul (MS), Brazil. This finding reinforces the importance of more detailed studies to determine the role of A. dubitatum in the transmission of spotted fever agents.

In vitro isolation from Amblyomma ovale (Acari: Ixodidae) and ecological aspects of the Atlantic rainforest Rickettsia, the causative agent of a novel spotted fever rickettsiosis in Brazil.

Recently, a novel human rickettsiosis, namely Atlantic rainforest spotted fever, was described in Brazil. We herein report results of a survey led around the index case in an Atlantic rainforest reserve in Peruibe municipality, southeastern Brazil. A Rickettsia parkeri-like agent (Rickettsia sp. Atlantic rainforest genotype) and Ricketsia bellii were isolated from adult Amblyomma ovale ticks collected from dogs. Molecular evidence of infection with strain Atlantic rainforest was obtained for 30 (12.9%) of 232 A. ovale adult ticks collected from dogs. As many as 88.6% of the 35 examined dogs had anti-Rickettsia antibodies, with endpoint titres at their highest to R. parkeri. High correlation among antibody titres in dogs, A. ovale infestations, and access to rainforest was observed. Amblyomma ovale subadults were found predominantly on a rodent species (Euryoryzomys russatus). From 17 E. russatus tested, 6 (35.3%) displayed anti-Rickettsia antibodies, with endpoint titres highest to R. parkeri. It is concluded that Atlantic rainforest genotype circulates in this Atlantic rainforest area at relatively high levels. Dogs get infected when bitten by A. ovale ticks in the forest, and carry infected ticks to households. The role of E. russatus as an amplifier host of Rickettsia to A. ovale ticks deserves investigation.