Hard ticks (Acari: Ixodidae) and tick-borne diseases of sheep and goats in Africa: A review.

Ticks are leading vectors of economically important pathogens that affect small ruminants due to favourable climatic conditions across different regions of the African continent. They are responsible for both direct and indirect economic losses in the livestock industry. This review focuses on the species diversity of hard ticks, their biology, tick-borne diseases of sheep and goats including non-infectious disease, and risk factors to tick infestation in Africa. Furthermore, our review provides recent updates on distribution of ticks and tick-borne pathogens of small ruminants in Africa. It was observed that several species and subspecies of hard ticks belonging to the genera Hyalomma (Hy), Rhipicephalus (Rh), Ixodes (I) and Amblyomma (Am) were found infesting small ruminants across the different regions of the continent. Of these genera, Rhipicephalus ticks accounts for the majority of the registered species, with exactly 27 different species infesting small ruminant stocks comprising of different developmental instars and adults of the tick. Rhipicephalus decolaratus, Rh. e. evertsi and Rh. appendiculatus were the three most common Rhipicephalus species reported. Both protozoal (Babesia and Theileria) and bacterial (Anaplasma, Rickettsia, Ehrlichia, Coxiella and Mycoplasma) pathogens have being reported to be amplified in several hard tick species and/or small ruminant hosts. Furthermore, tick paralysis and lameness were non-infectious conditions attributed to tick infestations. Amblyomma hebraeum and Rh. glabroscutatum may cause lameness in goats, while Hy. rufipes is responsible for the same condition in Merino sheep. Host paralysis due to a neurotoxin released by female Rh. e. evertsi and I. rubicundus has been documented within the continent. We therefore advocate for the need of integrated control measures against tick-borne pathogens (TBPs) including their arthropod vectors, to be performed simultaneously to ease the burden of vector-borne diseases in small ruminant production.

Candidatus Rickettsia Vini DNA in Ticks Collected from Nest Burrows of the European Sand Martin (Riparia riparia) in Sweden.

Background: Birds can cross geographical and environmental barriers and thereby facilitate dispersal of tick-borne pathogens both as carriers of infected ticks and as reservoirs of pathogenic microorganisms. Ixodes lividus (Ixodida: Ixodidae) is an endophilic tick in the Palearctic region that is highly specialized on its host, the European sand martin Riparia riparia. The purpose of this study was to determine whether I. lividus ticks sampled from sand martin nests in Sweden carry vector-borne pathogens. Materials and Methods: Fed ticks were collected in the autumns of 2017 and 2019 from the nests of a European sand martin colony in southern Sweden. Ticks were identified morphologically to developmental stage and species and were tested for tick-borne pathogens using PCR-based methods. Results: None of the 41 ticks tested positive for five tick-borne pathogens including Borrelia spp., tick-borne encephalitis virus (TBEV), Neoehrlichia mikurensis, Anaplasma phagocytophilum, and Babesia spp. Thirty-seven (13 females, 23 nymphs and 1 larva) of the 41 ticks tested positive for the gltA gene of Rickettsia spp. The sequences of the 17 kDa and gltA genes were most closely related to Candidatus Rickettsia vini. Conclusion: Our study confirms other reports that I. lividus ticks associated with the European sand martin have high infection prevalence of Ca. R. vini.

Immature hard ticks infected with Rickettsia amblyommatis on breeding birds from Pantanal.

Immature hard ticks from the genus Amblyomma feed on blood from a wide range of Neotropical avian hosts. They serve as vectors for pathogens of medical and veterinary importance, such as Rickettsia agents of the spotted fever group (SFG). Hence, determining ecological factors that increase encounter rates between immature ticks and their avian hosts may contribute to the understanding of tick-borne diseases transmission. Here, we used 720 individual birds from 96 species surveyed in the Brazilian Pantanal to test whether host breeding season influenced tick infestation probabilities. Additionally, collected ticks were screened for Rickettsia agents to describe new avian-tick-bacteria associations. Our models revealed that the probability of an individual bird being infested with immature ticks was similar during the breeding and pre-breeding season, but higher loads of immature tick stages were found during the breeding season. Host sex did not predict infestation probability, but Rickettsia agents recovered from ticks were more prevalent during the pre-breeding season. The new records of host usage by larvae and nymphs of Amblyomma in Pantanal and the growing body of tick surveys in Neotropical avian communities, suggest that immature ticks may benefit from avian blood sources during their annual cycle. The low number of infected ticks with Rickettsia agents on Pantanal birds suggest that this vertebrate group are likely not acting as reservoirs for these microorganisms. However, long-term surveys at the same site are imperative to determine which tick species are acting as reservoirs for Rickettsia agents in Pantanal and determine whether birds are playing a role in dispersing ticks and tick-borne pathogens.

Molecular detection and risk factors for Anaplasma platys infection in dogs from Egypt.

BACKGROUND: Anaplasma platys is a tick-borne bacterium which infects blood platelets of dogs, causing canine cyclic thrombocytopenia. The disease is distributed worldwide, particularly in the tropics and subtropics, but information on the epidemiology of A. platys infection in dogs is fragmentary in many countries, including Egypt. In this study, we investigated the prevalence and risk factors associated with A. platys infection in dogs from Egypt. METHODS: A conventional PCR targeting a fragment of the 16S rRNA gene of A. platys was used to screen 500 dogs from five North Egyptian governorates. DNA sequencing and phylogenetic analysis were performed for one of the positive samples. RESULTS: The overall prevalence of A. platys in the studied dogs was 6.4%. Females of the German shepherd breed without veterinary care had higher odds for A. platys positivity. High tick infestation and lack of anti-tick treatment were also identified as risk factors for A. platys infection. Phylogenetic analysis revealed that the sequence obtained herein was closely related to sequences from Egypt, South Africa and Uruguay. CONCLUSIONS: This is the first large-scale epidemiological study of A. platys in Egypt, where female German shepherd dogs without veterinary care, as well as dogs with high tick infestation and without anti-tick treatment are at a higher risk of infection.

Isolation and genetic characterization of a relapsing fever spirochete isolated from Ornithodoros puertoricensis collected in central Panama.

Tick-borne relapsing fever (TBRF) spirochetes are likely an overlooked cause of disease in Latin America. In Panama, the pathogens were first reported to cause human disease in the early 1900s. Recent collections of Ornithodoros puertoricensis from human dwellings in Panama prompted our interest to determine whether spirochetes still circulate in the country. Ornithodoros puertoricensis ticks were collected at field sites around the City of Panama. In the laboratory, the ticks were determined to be infected with TBRF spirochetes by transmission to mice, and we report the laboratory isolation and genetic characterization of a species of TBRF spirochete from Panama. Since this was the first isolation of a species of TBRF spirochete from Central America, we propose to designate the bacteria as Borrelia puertoricensis sp. nov. This is consistent with TBRF spirochete species nomenclature from North America that are designated after their tick vector. These findings warrant further investigations to assess the threat B. puertoricensis sp. nov. may impose on human health.

Prevalence and distribution of Anaplasma phagocytophilum in ticks collected from dogs in the United Kingdom.

BACKGROUND: Anaplasma phagocytophilum is the etiological agent of canine granulocytic anaplasmosis in dogs and causes human granulocytic anaplasmosis (HGA). Tick-borne anaplasmosis has been recognised as an emerging zoonotic health concern worldwide. The aim of the present study was to determine the prevalence of A. phagocytophilum in ticks collected from dogs in the UK and map its distribution. Routine surveillance of tick-borne disease is essential as part of a "One Health" approach to infectious disease management. METHODS: Tick DNA samples collected in 2015 as part of a large-scale tick surveillance programme were analysed using a previously validated diagnostic quantitative PCR for A. phagocytophilum. RESULTS: PCR analysis indicated that 138 out of 2994 tick DNA samples analysed were positive for A. phagocytophilum, a prevalence of 4.6% (95% CI: 3.89-5.42). Among these 138 tick DNA samples, 131 were from Ixodes ricinus, six were from Ixodes hexagonus and one was from Ixodes canisuga. Three of the I. ricinus tick DNA samples positive for A. phagocytophilum DNA were also positive for Borrelia spp. DNA and one was positive for Babesia spp. DNA, indicating co-infection. The ticks positive for the pathogen DNA were found widely distributed throughout the UK. CONCLUSIONS: These data provide important information on the prevalence and wide distribution of A. phagocytophilum in ticks infesting dogs within the UK.

Why Lyme disease is common in the northern US, but rare in the south: The roles of host choice, host-seeking behavior, and tick density.

Lyme disease is common in the northeastern United States, but rare in the southeast, even though the tick vector is found in both regions. Infection prevalence of Lyme spirochetes in host-seeking ticks, an important component to the risk of Lyme disease, is also high in the northeast and northern midwest, but declines sharply in the south. As ticks must acquire Lyme spirochetes from infected vertebrate hosts, the role of wildlife species composition on Lyme disease risk has been a topic of lively academic discussion. We compared tick-vertebrate host interactions using standardized sampling methods among 8 sites scattered throughout the eastern US. Geographical trends in diversity of tick hosts are gradual and do not match the sharp decline in prevalence at southern sites, but tick-host associations show a clear shift from mammals in the north to reptiles in the south. Tick infection prevalence declines north to south largely because of high tick infestation of efficient spirochete reservoir hosts (rodents and shrews) in the north but not in the south. Minimal infestation of small mammals in the south results from strong selective attachment to lizards such as skinks (which are inefficient reservoirs for Lyme spirochetes) in the southern states. Selective host choice, along with latitudinal differences in tick host-seeking behavior and variations in tick densities, explains the geographic pattern of Lyme disease in the eastern US.

Evidence of the presence of Borrelia burgdorferi in dogs and associated ticks in Egypt.

BACKGROUND: Borrelia burgdorferi is the spirochete that causes Lyme Borreliosis (LB), which is a zoonotic tick-borne disease of humans and domestic animals. Hard ticks are obligate haematophagous ectoparasites that serve as vectors of Borrelia burgdorferi. Studies on the presence of Lyme borreliosis in Egyptian animals and associated ticks are scarce. METHODS: This study was conducted to detect B. burgdorferi in different tick vectors and animal hosts. Three hundred animals (dogs=100, cattle=100, and camels=100) were inspected for tick infestation. Blood samples from 160 tick-infested animals and their associated ticks (n=1025) were collected and examined for the infection with B. burgdorferi by polymerase chain reaction (PCR) and sequencing of the 16S rRNA gene. The identified tick species were characterized molecularly by PCR and sequencing of the ITS2 region. RESULTS: The overall tick infestation rate among examined animals was 78.33% (235/300). The rate of infestation was significantly higher in camels (90%), followed by cattle (76%) and dogs (69%); (P = 0.001). Rhipicephalus sanguineus, Rhipicephalus (Boophilus) annulatus, and both Hyalomma dromedarii and Amblyomma variegatum, were morphologically identified from infested dogs, cattle, and camels; respectively. Molecular characterization of ticks using the ITS2 region confirmed the morphological identification, as well as displayed high similarities of R. sanguineus, H. dromedarii, and A. Variegatu with ticks identified in Egypt and various continents worldwide. Just one dog (1.67%) and its associated tick pool of R. sanguineus were positive for B. burgdorferi infection. The 16S rRNA gene sequence for B. burgdorferi in dog and R. sanguineus tick pool showed a 100% homology. CONCLUSION: Analyzed data revealed a relatively low rate of B. burgdorferi infection, but a significantly high prevalence of tick infestation among domesticated animals in Egypt, which possesses a potential animal and public health risk. Additionally, molecular characterization of ticks using the ITS2 region was a reliable tool to discriminate species of ticks and confirmed the morphological identification.

Spatial distribution and molecular epidemiology of hemotropic Mycoplasma spp. and Mycoplasma haemocanis infection in dogs from Rio de Janeiro, Brazil.

This cross-sectional study aims to investigate the epidemiology and spatial distribution of hemotropic Mycoplasma spp. and Mycoplasma haemocanis in dogs from Rio de Janeiro, Brazil. Blood samples were collected at random from 437 household dogs. An epidemiological questionnaire was completed concerning the host characteristics as well as the environments in which they lived. A positivity frequency of 17.84% (78/437) was found for Mycoplasma spp. and 2% (9/437) for M. haemocanis in Rio de Janeiro, Brazil, through molecular detection based on the 16S rRNA sequence. According to the present study, dogs that live in households with the presence of rodents (odds ratio [OR] = 9.93; p-value = 0.02; confidence interval [CI]: 1.34-73.66) and wild animals (OR = 1.91; p-value = 0.03; CI: 1.06-3.42) are more likely to be infected with Mycoplasma spp.. Also, dogs with tick infestation (OR = 6.47; p-value = 0.007; CI: 1.63-25.60) have more chances to become infected with M. haemocanis. The spatial analysis disclosed a positive correlation between the Mycoplasma presence and tick infestation (global Moran index = 0.82; pseudo-p-value =0.001). The epidemiological findings support the hypothesis of Rhipicephalus sanguineus s.l. as the vector of M. haemocanis in the studied region and provide insightful information to prevent the Mycoplasma spp. infection in dogs from Rio de Janeiro.

Ixodes spp. from Dogs and Cats in the United States: Diversity, Seasonality, and Prevalence of Borrelia burgdorferi and Anaplasma phagocytophilum.

Ixodes spp. are commonly found on dogs and cats throughout the world. In the eastern United States, 16S rDNA sequence of Ixodes scapularis, the predominant species, reveals two clades-American and Southern. To confirm the species and clades of Ixodes spp. ticks submitted from pets, we examined ticks morphologically and evaluated 16S rDNA sequence from 500 ticks submitted from 253 dogs, 99 cats, 1 rabbit, and 1 ferret from 41 states. To estimate pathogen prevalence, flaB of Borrelia burgdorferi (Bb) sensu stricto and 16S rDNA of Anaplasma phagocytophilum (Ap) were amplified and sequenced. Most Ixodes spp. from the Northeast (n = 115/115; 100%) and the Midwest (n = 77/80; 96.3%) were I. scapularis, American clade. Borrelia spp. were identified in 34 of 192 (17.8%) and Ap in 5 of 192 (2.6%) I. scapularis. Two Ixodes cookei and one Ixodes texanus were identified from Ohio, Illinois, and Michigan. In contrast, 156 of 261 (59.8%) Ixodes spp. from the Southeast were I. scapularis, American clade; 86 of 261 (33.0%) were I. scapularis, Southern clade; 9 of 261 (3.4%) were Ixodes affinis; and 10 of 261 (3.8%) were I. cookei. Southern clade was significantly more common in Florida and less common in the upper South (p < 0.0001). One I. scapularis (1/242; 0.4%) from the Southeast (Kentucky) tested positive for Bb and 6 of 242 (2.5%) were positive for Ap. In the West, most (34/44; 77.3%) Ixodes spp. were Ixodes pacificus, with Ixodes angustus (n = 6) submitted from dogs in Alaska, Washington, and Oregon and Ixodes haerlei (n = 4) preliminarily identified from a dog in Montana. Pathogens were not detected in any ticks from the West. Although I. scapularis, American clade, predominated in the Northeast and Midwest, additional Ixodes spp. were found on dogs and cats in other regions and pathogens were less commonly detected. The role of less common Ixodes spp. as disease vectors, if any, warrants continued investigation.

A combined transcriptomic approach to identify candidates for an anti-tick vaccine blocking B. afzelii transmission.

Ixodes ricinus is the vector for Borrelia afzelii, the predominant cause of Lyme borreliosis in Europe, whereas Ixodes scapularis is the vector for Borrelia burgdorferi in the USA. Transcription of several I. scapularis genes changes in the presence of B. burgdorferi and contributes to successful infection. To what extend B. afzelii influences gene expression in I. ricinus salivary glands is largely unknown. Therefore, we measured expression of uninfected vs. infected tick salivary gland genes during tick feeding using Massive Analysis of cDNA Ends (MACE) and RNAseq, quantifying 26.179 unique transcripts. While tick feeding was the main differentiator, B. afzelii infection significantly affected expression of hundreds of transcripts, including 465 transcripts after 24 h of tick feeding. Validation of the top-20 B. afzelii-upregulated transcripts at 24 h of tick feeding in ten biological genetic distinct replicates showed that expression varied extensively. Three transcripts could be validated, a basic tail protein, a lipocalin and an ixodegrin, and might be involved in B. afzelii transmission. However, vaccination with recombinant forms of these proteins only marginally altered B. afzelii infection in I. ricinus-challenged mice for one of the proteins. Collectively, our data show that identification of tick salivary genes upregulated in the presence of pathogens could serve to identify potential pathogen-blocking vaccine candidates.

Myocarditis secondary to Borrelia infection in a dog: a case report.

The aim of this study was to recognise the etiological factor of a disease with symptoms of lameness and cardiac failure, which occurred in one dog 4 weeks after invasion by ticks. A serological examination as well as molecular examination (PCR) was done. In the sample of the serum, the presence of antibodies specific to Borrelia burgdorferi were detected. Antibiotic therapy with doxycycline did not cause significant improvement, so the owners of the dog decided about its euthanasia. During the necroscopy, a dilated heart was recognised. In the heart samples, the genetic material of Borrelia was detected. The results of serological and molecular examinations showed that in the discussed case, an etiological factor of the disease was spirochetes. In light of the research, veterinary practitioners should keep in mind the presence of Lyme disease in dogs in Poland and include it in differential diagnoses for lameness and cardiological problems.

Tick-borne pathogens in Ixodes ricinus ticks collected from migratory birds in southern Norway.

Birds are important hosts for the first life stages of the Ixodes ricinus tick and they can transport their parasites over long distances. The aim of this study was to investigate the prevalence of Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, Neoehrlichia mikurensis and Rickettsia helvetica in ticks collected from migratory birds in Norway. A total of 815 Ixodes ricinus ticks from 216 birds trapped at Lista Bird Observatory in southern Norway during spring and autumn migration in 2008 were analysed by real-time PCR. B. burgdorferi s. l. was the most prevalent pathogen, detected in 6.1% of the ticks. The prevalence of N. mikurensis, A. phagocytophilum and R. helvetica was 1.2%, 0.9% and 0.4% respectively. In addition, one sample (0.1%) was positive for B. miyamotoi. In total, 8.2% of the ticks were infected with at least one pathogen. Co-infection with B. burgdorferi s. l. and N. mikurensis or A. phagocytophilum was found in 6.0% of the infected ticks. Our results show that all the known major tick-borne bacterial pathogens in Norway are subject to transport by migratory birds, potentially allowing spread to new areas. Our study showed a surprisingly high number of samples with PCR inhibition (57%). These samples had been extracted using standard methodology (phenol-chloroform extraction). This illustrates the need for inhibition controls to determine true prevalence rates.

Quantitative analysis of Anaplasma marginale acquisition and transmission by Dermacentor andersoni fed in vitro.

In this study, we describe a new in vitro tick feeding system that facilitates the study of ticks and tick-borne pathogens. To optimize the system, we used Dermacentor andersoni and Anaplasma marginale as a tick-pathogen interaction model. Ticks were fed on bovine blood containing 10-fold dilutions of the pathogen to determine the effect of dose on tick infection rate. After feeding on infected blood, ticks were transferred to uninfected blood to stimulate bacterial replication within the tick vector. During stimulation feeding, blood samples were collected daily to determine if infected ticks secreted viable A. marginale. The results demonstrated similar attachment rates between the first and second tick feeding. Tick midgut and salivary glands were infected with A. marginale. However, salivary gland infection rates decreased as the percentage of parasitized erythrocytes decreased during tick acquisition feeding. Bacteria recovered from the in vitro system were able to infect a naïve bovine host. Using the highly transmissible A. marginale St. Maries strain, we demonstrated that the artificial tick feeding system is a suitable tool to study tick-pathogen interactions and that A. marginale tick salivary gland infection is dose dependent. This work demonstrates the utility of an artificial tick feeding system to directly study the association between the number of acquired pathogens and transmissibility by ticks.

Molecular detection of avian spirochete Borrelia anserina in Argas persicus ticks in Algeria.

Argasid ticks are one of the most important poultry ectoparasites. They affect poultry directly through blood meal and indirectly through the transmission of pathogens essentially Borrelia anserina, agent of avian borreliosis, one of the most widespread poultry diseases in the world, and is of great economic importance. This study was conducted between April 2014 and March 2015 in the region of Ksar El Boukhari, Algeria, in order to investigate the presence of soft ticks in laying hen farms and to detect B. anserina bacteria using molecular tools. DNA was extracted and screened for the presence of Borrelia spp. DNA by real-time polymerase chain reaction (qPCR). Borrelia spp. screening was performed using primers and probe targeting the 16S rRNA gene. A total of 83 traditional laying hen farms were visited, of which 39 (46.98 %) were found infested with A. persicus tick. Molecular analysis revealed that 2/34 (5.88 %) of ticks were infected by B. anserina. None of the ticks tested were positive for Rickettsia spp., and Coxiella burnetii. These results constitute the first report in Algeria of A. persicus harboring B. anserina.

Prevention of transmission of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum by Ixodes spp. ticks to dogs treated with the Seresto® collar (imidacloprid 10% + flumethrin 4.5%).

The capability of imidacloprid 10% + flumethrin 4.5% (Seresto®) collars to prevent transmission of Borrelia burgdorferi sensu lato (Bbsl) and Anaplasma phagocytophilum (Ap) by naturally infected ticks was evaluated in two studies with 44 dogs. In each study, one group served as non-treated control, whereas the other groups were treated with the Seresto® collar. All dogs were exposed to naturally Bbsl- and Ap-infected hard ticks (Ixodes ricinus, Ixodes scapularis). In study 1, tick infestation was performed on study day (SD) 63 (2 months post-treatment [p.t.]); in study 2, it was performed on SD 32 (one month p.t.) respectively SD 219 (seven months p.t.). In situ tick counts were performed 2 days after infestation. Tick counts and removals followed 6 (study 1) or 5 days (study 2) later. Blood sampling was performed for the detection of specific Bbsl and Ap antibodies and, in study 1, for the documentation of Ap DNA by PCR. Skin biopsies were examined for Bbsl by PCR and culture (only study 1). The efficacy against Ixodes spp. was 100% at all time points. In study 1, two of six non-treated dogs became infected with Bbsl, and four of six tested positive for Ap; none of the treated dogs tested positive for Bbsl or Ap. In study 2, ten of ten non-treated dogs became infected with Bbsl and Ap; none of the treated dogs tested positive for Bbsl or Ap; 100% acaricidal efficacy was shown in both studies. Transmission of Bbsl and Ap was successfully blocked for up to 7 months.

Molecular identification of protozoal and bacterial organisms in domestic animals and their infesting ticks from north-eastern Algeria.

A molecular survey was undertaken to determine the presence of protozoal and bacterial organisms in 120 ticks and 87 blood samples collected from mammals in north-eastern Algeria. Eight tick species were morphologically identified including 70 Rhipicephalus (Boophilus) annulatus, 23 Rhipicephalus bursa, five Rhipicephalus sanguineus sensu lato, 11 Hyalomma impeltatum, five Hyalomma scupense, two Hyalommma marginatum, one Hyalomma anatolicum and three Ixodes ricinus. Quantitative PCR screening of the ticks showed that Theileria annulata, "Candidatus Ehrlichia urmitei", Theileria buffeli and Anaplasma platys were detected in Rh. annulatus. Rickettsia massiliae and Anaplasma ovis were detected in Rh. sanguineus s.l. and Rh. bursa. Rickettsia aeschlimannii was detected in Hy. marginatum, Hy. scupense and Hy. impeltatum. Finally, "Candidatus Rickettsia barbariae" was detected in Rh. bursa. In the screening blood samples, Theileria equi, T.annulata, T. buffeli, Babesia bovis, Anaplasma marginale, A. ovis and Borrelia spp. were detected in cattle. Theileria ovis, T. annulata, and A. ovis were detected in sheep. In addition, A. ovis and T. equi were detected in goats and equidea respectively. In this study, T. equi and "Candidatus Rickettsia barbariae" were identified for the first time in Algeria as well as potential new species of Ehrlichia and Anaplasma. Although molecular detection does not indicate vector/reservoir competence when investigating ticks removed from animals, this study expands the knowledge of the microorganisms detected in ticks in north-east of Algeria.

Experimental infection of Monodelphis domestica with Rickettsia parkeri.

This study aimed to evaluate the infection of the marsupial Monodelphis domestica (the gray short-tailed opossum) by Rickettsia parkeri and its role as an amplifier of the bacterium for Amblyomma ticks. Ten M. domestica males were inoculated with phosphate-buffered saline (PBS) and 106 Vero cells infected with R. parkeri. In seven animals, inoculation was intramuscular, and in three intraperitoneal. One male (control) received 1 ml of the same vehicle used for inoculation intraperitoneally. The three animals inoculated intraperitoneally were infested with uninfected A. sculptum larvae and nymphs between the 2nd and 9th day post-infection (DPI). Parasitemia was monitored from the 3rd to 9th DPI by polymerase chain reaction, using primers for 17 kDa and ompA. The animals were also clinically evaluated. Of the animals infected intramuscularly, only one was blood-positive by the 5th DPI. The three animals infected intraperitoneally were blood-positive on the 2nd, 5th, 7th, and 9th DPI. Of the ten pools of recovered engorged ticks, six had positive bands. The kidney, liver, heart, and spleen of an intramuscularly infected animal were also positive. The rectal temperature of the animals tested increased only in the first three DPI. The animals inoculated intraperitoneally showed prostration, bristled hair, and weight loss. The study found that R. parkeri was capable of infecting M. domestica, which developed rickettsemia and caused infection in xenodiagnostic ticks.