First Evidence of Ehrlichia minasensis Infection in Horses from Brazil

Tick-borne pathogens in small mammals from the Pantanal biome, Brazil

The order Piroplasmida (e.g., Babesia, Theileria, Cytauxzoon, and Rangelia) and order Eucoccidiorida, Suborder Adelorina (e.g., Hepatozoon) comprise protozoa of the phylum Apicomplexa. At the same time, the Anaplasmataceae family (Order Rickettsiales) encompasses important bacterial pathogens, notably the genera Anaplasma and Ehrlichia. All these genera of agents have pathogenic species transmitted to vertebrate hosts via ticks and pose significant economic, veterinary, and medical concerns. Biological samples of small mammals (Rodentia and Didelphiomorphia) collected between 2015 and 2018, as part of a study on the eco-epidemiological aspects of Brazilian spotted fever, were made available to investigate the molecular prevalence of Piroplasmida, Hepatozoon species, and Anaplasmataceae agents. The study included 28 marsupials of the species Gracilinanus agilis and 62 rodents, which comprised Cerradomys subflavus, Dasyprocta azarae, Hylaeamys megacephalus, Necromys lasiurus, and Oecomys mamorae. All individuals were captured in the municipality of Poconé in the Brazilian Pantanal, located in midwestern Brazil. Among 333 biological samples, including blood (n=85), spleen (n=85), liver (n=90), and lung (n=73), Hepatozoon were molecularly detected in cricetid rodents H. megacephalus (n=2) and Oecomys sp. (n=1), representing 3.3 % of the small mammals surveyed. Positive results for Anaplasma sp. were observed in 21 (23.3 %) animals, including H. megacephalus (n=15), Oecomys sp. (n=1), four rodents not identified at the species level, and the marsupial G. agilis (n=1). All biological samples were negative for Piroplasmida. Phylogenetic analysis of a partial 18S rRNA gene sequence from Hepatozoon sp. detected in H. megacephalus clustered into a clade with Hepatozoon sp. identified in Cuniculus paca from the Brazilian Amazon. In addition, a Bayesian phylogenetic inference based on the 16S ribosomal RNA gene (16S rRNA) from members of the Anaplasmataceae family obtained from H. megacephalus, Oecomys sp., and an unidentified rodent clustered together. This cluster was part of a sub-clade with two Anaplasma sp. sequences from Amblyomma coelebs nymphs collected from coatis (Nasau nasua) in southern Brazil and 'Candidatus Anaplasma sparouinense' detected in a human from French Guiana. In conclusion, we provide strong evidence of a high occurrence of Anaplasma genotypes infecting Cricetidae rodents in the Pantanal biome, which suggests that humans may be at risk of infection by an Anaplasma genotype closely related to 'Ca. A. sparouinense', responsible for an unusual case of human anaplasmosis in the Amazon rainforest. Given the potential involvement of rodents and marsupials in the natural cycle and transmission of these neotropical Anaplasma species, further investigations are needed to evaluate their role as sources of novel human infections.

Ehrlichia Species in Dromedary Camels (Camelus dromedarius) and Ruminants from Somalia

Ehrlichioses, caused by Ehrlichia species, are tick-borne diseases (TBDs) that affect animals and humans worldwide. This study aimed to investigate the molecular occurrence of Ehrlichia spp. in 530 animals (155 Dromedary camels, 199 goats, 131 cattle, and 45 sheep) in the Benadir and Lower Shabelle regions of Somalia. Blood DNA samples were tested for PCR targeting dsb and sodB genes of Ehrlichia spp. and PCS20 and map1 genes of E. ruminantium. The obtained sequences were submitted for phylogenetic analyses. Ehrlichia spp. were detected in 26.4% (140/530) of animals by dsb-PCR, with the highest prevalence in dromedary camels (54.8%), followed by cattle (29.8%), goats (7.0%), and sheep (4.4%). Dromedary camels, cattle, and goats had significantly higher infection odds compared to sheep (p < 0.05). Among dsb-PCR-positive samples, 76.9% (30/39) of cattle tested sodB-positive, while other species were negative. E. ruminantium was detected in 13.7% (18/131) of cattle by pCS20-PCR, but none were positive for the map1 gene. Phylogenetic analysis confirmed E. minasensis in camels, sheep, and goats and E. ruminantium in cattle, marking the first molecular evidence of E. minasensis in dromedary camels, sheep, and goats globally, and E. ruminantium in cattle from Somalia. These findings emphasize the need for further research on its economic and public health impact.

Ehrlichia sp. in dairy cattle from Bahia, Brazil: high seropositivity rates and molecular confirmation of Ehrlichia minasensis

BACKGROUND

Ehrlichia spp. are obligate intracytoplasmic Gram-negative tickborne bacteria from the Anaplasmataceae family. Ehrlichiosis is considered an emerging disease in humans and animals. Studies on bovine ehrlichiosis are scarce in Northeastern Brazil. Therefore, the objectives of this work were to determine the frequency of antibodies anti-Ehrlichia sp. in dairy cattle herds in the Feira de Santana microregion, Bahia, and to confirm infection through PCR and nucleotide sequencing in selected seropositive animals.

RESULTS

Blood samples were collected from 256 clinically healthy adult cattle from four dairy farms. Plasma from each animal was tested for Ehrlichia sp. using an indirect immunofluorescence antibody test (IFAT) and a 1:40 cutoff. Of the 256 tested samples, 249 (97.26%) were seropositive for Ehrlichia sp. Forty blood samples (10 from each farm) from IFAT-positive cattle were examined by a PCR for Ehrlichia sp. and resulted in 13 infected animals; DNA samples from six PCR-positive cows were sequenced and matched 100% with Ehrlichia minasensis.

CONCLUSIONS

The results represent the first serological and molecular evidence of E. minasensis in cattle from Bahia state and northeastern Brazil. Despite the limited number of tested cattle, the high frequency of seropositive animals in four farms suggests that Ehrlichia sp. is widely disseminated in the studied microregion. Considering that the infected cattle were asymptomatic, it is possible that they developed protective immunity against Ehrlichia sp.

Molecular detection and characterization of Anaplasmataceae agents, Bartonella spp. and hemoplasmas in armadillos and anteaters from Brazil

Armadillos and anteaters exhibit a wide range of interactions with various pathogens and ectoparasites, which, along with their physiological and ecological characteristics, contribute to their potential as hosts for a broad variety of pathogens with zoonotic potential. However, there has been limited research into the occurrence and diversity of vector-borne agents in this group of mammals. The present study aimed to investigate the occurrence and molecular identity of Ehrlichia spp., Anaplasma spp., Bartonella spp. and hemotropic mycoplasmas (hemoplasmas) in free-ranging armadillos and anteaters sampled in the southeast and central-west regions of Brazil. To this purpose, 167 biological samples (139 blood and 28 spleen) from Xenarthra mammals sampled in the states of São Paulo and Mato Grosso do Sul were analyzed: 48 from six-banded armadillos (Euphractus sexcinctus), 29 from giant armadillos (Priodontes maximus), 4 from nine-banded armadillos (Dasypus novemcinctus), 1 from naked-tailed armadillo (Cabassous unicinctus), 79 from giant anteaters (Myrmecophaga tridactyla) and 6 from southern tamanduas (Tamandua tetradactyla). Screening PCR assays were performed for Ehrlichia spp. based on the dsb gene, nested PCR for Anaplasma spp. and PCR for hemotropic mycoplasmas based on the 16S rRNA gene, and qPCR for Bartonella spp. based on the 16-23S rRNA intergenic region (ITS). The positive samples were additionally subjected to PCR assays targeting different molecular markers for molecular characterization. As a result, 1/48 (0.59%) blood sample from E. sexcintus was positive for Anaplasma spp., and 1/79 (0.59%) blood sample from M. tridactyla was positive for Ehrlichia spp. The 16S rRNA sequence of Anaplasma sp. detected in E. sexcintus clustered within the same clade as 'Candidatus Anaplasma brasiliensis', previously detected in T. tetradactyla. The dsb sequence of Ehrlichia sp. detected in M. tridactyla clustered within the same clade as Ehrlichia minasensis. In the PCR tests for hemoplasmas, 31/46 (64.5%) E. sexcinctus, 9/29 (65.5%) P. maximus, 2/4 (50%) D. novemcinctus, 33/79 (41.7%) M. tridactyla, and 2/6 (33.3%) T. tetradactyla tested positive. The 16S rRNA and 23S rRNA sequences of hemoplasmas found in E. sexcinctus clustered within the same clade as 'Candidatus Mycoplasma haematomaximus', which was previously detected in P. maximus in Brazil. High positivity rates were also observed for Bartonella spp., with 23/48 (47.9%) E. sexcinctus, 1/4 (25%) D. novemcinctus, 9/29 (31%) P. maximus, 21/79 (26.5%) M. tridactyla, and 3/6 (50%) T. tetradactyla showing positive results. The ftsZ sequences of Bartonella sp. detected in E. sexcinctus clustered with 'Candidatus Bartonella washoensis subsp. brasiliensis', previously identified in six-banded armadillos in Brazil. These findings reinforce the presence of 'Candidatus Anaplasma brasiliensis' and 'Candidatus Bartonella washoensis subsp. brasiliensis' in armadillos, and Ehrlichia minasensis in anteaters. This is the first report of 'Candidatus Mycoplasma haematomaximus', a hemoplasma previously described in giant armadillos, in six-banded armadillos. The zoonotic potential and real significance of infection by these agents in xenarthrans' health and conservation efforts are yet to be investigated.

Aetiologies of bacterial tick-borne febrile illnesses in humans in Africa: diagnostic limitations and the need for improvement

Tick-borne febrile illnesses caused by pathogens like Anaplasma spp., Bartonella spp., Borrelia spp., Ehrlichia spp., Coxiella burnetii, Francisella tularensis, and Rickettsia spp., are significant health concerns in Africa. The epidemiological occurrence of these pathogens is closely linked to the habitats of their vectors, prevalent in rural and semi-urban areas where humans and livestock coexist. The overlapping clinical presentations, non-specific symptoms, and limited access to commercially available in vitro diagnostics in resource-limited settings exacerbate the complexity of accurate diagnoses. This review aimed to systematically extract and analyze existing literature on tick-borne febrile illnesses in Africa, highlighting the diagnostic challenges and presenting an up-to-date overview of the most relevant pathogens affecting human populations. A comprehensive literature search from January 1990 to June 2024 using databases like PubMed, Cochrane Library, Science Direct, EMBASE, and Google Scholar yielded 13,420 articles, of which 70 met the inclusion criteria. Anaplasma spp. were reported in Morocco, Egypt, and South Africa; Francisella spp. in Kenya and Ethiopia; Ehrlichia spp. in Cameroon; Bartonella spp. in Senegal, Namibia, South Africa, and Ethiopia; Borrelia spp. in Senegal, Gabon, Tanzania, and Ethiopia; Coxiella burnetii in 10 countries including Senegal, Mali, and South Africa; and Rickettsia spp. in 14 countries including Senegal, Algeria, and Uganda. Data were analyzed using a fixed-effect model in R version 4.0.1 and visualized on an African map using Tableau version 2022.2. This review highlights the urgent need for improved diagnostics to better manage and control tick-borne febrile illnesses in Africa.

Diversity of Anaplasmataceae Transmitted by Ticks (Ixodidae) and the First Molecular Evidence of Anaplasma phagocytophilum and Candidatus Anaplasma boleense in Paraguay

Anaplasmataceae bacteria are emerging infectious agents transmitted by ticks. The aim of this study was to identify the molecular diversity of this bacterial family in ticks and hosts, both domestic and wild, as well as blood meal sources of free-living ticks in northeastern Paraguay. The bacteria were identified using PCR-HRM, a method optimized for this purpose, while the identification of ticks and their blood meal was performed using conventional PCR. All amplified products were subsequently sequenced. The bacteria detected in the blood hosts included Ehrlichia canis, Anaplasma platys, and Anaplasma phagocytophilum, Candidatus Anaplasma boleense, and Wolbachia spp., which had not been previously reported in the country. Free-living and parasitic ticks on dogs (Canis lupus familiaris) and wild armadillos (Dasypus novemcinctus) were collected and identified as Rhipicephalus sanguineus and Amblyomma spp. The species E. canis, A. platys, A. phagocytophilum, and Ca. A. boleense were detected in domestic dog ticks, and E. canis and A. platys were found for the first time in armadillos and free-living ticks. Blood feeding sources detected in free-living ticks were rodents, humans, armadillos and dogs. Results show a high diversity of tick-borne pathogens circulating among domestic and wild animals in the northeastern region of Paraguay.

Phylogenetic analysis of Ehrlichia species isolated from horses and dogs in Iran

This study aimed to determine the prevalence and phylogenetic analysis of Ehrlichia spp. in horses and dogs in Iran. Blood samples were collected from 400 animals, including 200 horses and 200 dogs, from five different provinces in Iran. Polymerase chain reaction (PCR) was used to detect Ehrlichia spp. based on amplification of the 16S rRNA gene. The semi-nested PCR method was used to amplify the dsb, TRP36, and gltA genes. The results showed that 4.5 % of the samples (3 % horses and 6 % dogs) were positive for Ehrlichia sp. The highest prevalence was observed in Kerman and Khuzestan, while the lowest was found in West Azerbaijan, Golestan, and Mazandaran. The study suggests that the populations of dogs and horses in the country should be considered important factors in the epidemiology of ehrlichiosis. Phylogenetic analysis based on the dsb and TRP36 genes revealed that the prevalent species were E. canis and E. ruminantium.

First report on tick-borne pathogens detected in ticks infesting stray dogs near butcher shops

Public health is a major concern for several developing countries due to infectious agents transmitted by hematophagous arthropods such as ticks. Health risks due to infectious agents transmitted by ticks infesting butcher-associated stray dogs (BASDs) in urban and peri-urban regions have been neglected in several developing countries. To the best of the authors' knowledge, this is the first study assessing public health risks due to ticks infesting BASDs in Pakistan's urban and peri-urban areas. A total of 575 ticks (390 from symptomatic and 183 from asymptomatic BASDs) were collected from 117 BASDs (63 symptomatic and 54 asymptomatic); the ticks belonged to 4 hard tick species. A subset of each tick species' extracted DNA was subjected to polymerase chain reaction (PCR) to amplify the 16S rDNA and cox1 sequences of the reported tick species, as well as bacterial and protozoal agents. The ticks' 16S rDNA and cox1 sequences showed 99-100% identities, and they were clustered with the sequence of corresponding species from Pakistan and other countries in phylogenetic trees. Among the screened 271 ticks' DNA samples, Anaplasma spp. was detected in 54/271 (19.92%) samples, followed by Ehrlichia spp. (n = 40/271, 14.76%), Rickettsia spp. (n = 33/271, 12.17%), Coxiella spp. (n = 23/271, 4.48%), and Hepatozoon canis (n = 9/271, 3.32%). The obtained sequences and phylogenetic analyzes revealed that the pathogens detected in ticks were Ehrlichia minasensis, Ehrlichia sp., Hepatozoon canis, Coxiella burnetii, Coxiella sp., Anaplasma capra, Anaplasma platys, Anaplasma sp., Rickettsia massiliae, "Candidatus Rickettsia shennongii" and Rickettsia aeschlimannii. Tick-borne pathogens such as E. minasensis, H. canis, A. capra, A. platys, and R. aeschlimannii, were detected based on the DNA for the first time in Pakistan. This is the first report on public health risks due to ticks infesting BASDs. These results not only provided insights into the occurrence of novel tick-borne pathogens in the region but also revealed initial evidence of zoonotic threats to both public health and domestic life.

Molecular detection and genetic characterization of Ehrlichia canis and Ehrlichia sp. in neotropical primates from Brazil

The Anaplasmataceae family includes obligate, arthropod-transmitted intracellular bacteria that can be zoonotic and potentially fatal. Studies focusing on the interaction between neotropical primates and the agents of this family are scarce. The present study aimed to identify agents of the Anaplasmataceae family in the whole blood of free-living and captive neotropical primates in the State of Mato Grosso, Central-West Brazil. Thirty-eight samples of six nonhuman primate (NHP) species were collected in seven municipalities and analysed through polymerase chain reaction (PCR), nucleotide sequencing, and phylogenetic analysis of the dsb, groEL, 16S rRNA, and gltA genes. DNA fragments similar to those of Ehrlichia canis were detected in Sapajus apella and Ehrlichia chaffeensis from Mico melanurus. The sequences generated in this study and homologous sequences retrieved from GenBank® were used for phylogenetic analyses to characterize the Ehrlichial agents detected in NHPs. The agents were then grouped into clades corresponding to different isolates from the NHP species. In addition, an Anaplasma sp. closely related to Anaplasma marginale was identified in two S. apella individuals. These findings shed light on the susceptibility of neotropical NHPs to Anaplasmataceae agents. These bacteria are known to be transmitted by ticks, which can also serve as possible sources of infection for other animals, including humans.

An ecological and epidemiological single-season survey of Anaplasma and Ehrlichia positive ticks in Victoria Falls National Park, Zimbabwe

There is an urgent need for continued research on the ecology of tick-borne diseases in Africa. Our objective was to provide a preliminary description of the ecology and epidemiology of tick species, tick-borne pathogens, and animal hosts in Zimbabwe, focusing efforts at Victoria Falls National Park, for a single season. We tested the hypothesis that tick surveillance and pathogen screening data can be used to model associations among ticks, hosts, and pathogens. We collected ticks from domesticated animals and wildlife in Zimbabwe and screened the ticks for the presence of Anaplasma and Ehrlichia bacteria. Nearly 30% of the screened ticks were PCR-positive; 89% of tick species were PCR-positive, and 88% of animal species carried at least one PCR-positive tick. We sequenced a subset of amplicons that were similar to three Anaplasma species and three Ehrlichia species. The odds of a tick being PCR-positive increased when many ticks were collected from the host or the tick was collected from a cow (domesticated animal). Tick species shared host species more often than expected. We demonstrate that ticks in northwestern Zimbabwe present a One Health problem for nearby wildlife and humans.

Lice and lice-borne diseases in humans in Africa: a narrative review

Lice are host-specific insects. Human lice include Pediculus humanus humanus (body lice) which are known to be vectors of serious human bacterial infectious diseases including epidemic typhus, relapsing fever, trench fever and plague; Pediculus humanus capitis (head lice) that frequently affect children; and Pthirus pubis, commonly known as crab lice. In Africa, human infections transmitted by lice remained poorly known and therefore, underestimated, perhaps due to the lack of diagnostic tools and professional knowledge. In this paper we review current knowledge of the microorganisms identified in human lice in the continent of Africa, in order to alert health professionals to the importance of recognising the risk of lice-related diseases.

Challenges of Diagnosing Severe Ehrlichiosis in Orthotopic Liver Transplant Recipients

In recent solid organ transplant recipients, acute febrile illness is usually a source of grave concern and a diagnostic dilemma, especially if no response is noted after initiation of broad antimicrobial therapy. Human Monocytic Ehrlichiosis (HME) is a tick-borne illness caused by Ehrlichia chaffeensis and is not considered an opportunistic infection in immunocompromised patients such as solid organ transplant patients. Ehrlichiosis in immunocompromised patients can be life-threatening, and a strong index of suspicion is needed, especially in patients who live in endemic areas, for proper treatment initiation with doxycycline. We report a case of a 40-year-old male who received an orthotopic liver transplant six months earlier secondary to primary sclerosing cholangitis, on chronic immunosuppressive medication, who presented with complaints of sudden onset fever associated with nausea, vomiting, and diarrhea. Initial extensive infectious workup was negative and no response to empiric antimicrobials. There was suspicion for ehrlichiosis prompting empiric doxycycline use. Subsequently, E. chaffeensis polymerase chain reaction (PCR) was positive, and the antibiotic regimen was de-escalated to only doxycycline with complete resolution of his symptoms and progressive improvement in previously abnormal biochemical indices.

Serological evidence of Ehrlichia minasensis infection in Brazilian dogs

Ehrlichia spp. are important tick-borne pathogens of animals in Brazil, and Ehrlichia canis is the most prevalent species infecting dogs. Moreover, Ehrlichia minasensis has also recently been identified as a novel ehrlichial agent that infects cattle in Brazil. The objective of this study was to determine whether dogs could be infected by E. minasensis. To investigate this possibility, sera (n = 429) collected from dogs in the Pantanal region were retrospectively analyzed for the presence of antibodies against E. canis and E. minasensis. Canine sera were screened by two isolates of E. canis in indirect immunofluorescence assay (IFA) and the majority (n = 298; 69.4%) had antibodies with endpoint titers ranging from 80 to 327,680. In order to further confirm E. canis-specific antibodies, IFA positive sera were analyzed by ELISA using E. canis-specific peptides (i.e. TRP19 and TRP36 US/BR/CR), which detected E. canis antibodies in 80.2% (239/298) of the dog sera. Fifty-nine (13.7%) samples had detectable antibodies to E. canis by IFA but were negative by E. canis peptide ELISA. These sera were then tested by E. minasensis IFA (Cuiaba strain) as antigen and 67.8% (40/59) were positive (titers ranging from 80 to 20,480). Eleven sera had antibody titers against E. minasensis at least two-fold higher than observed for E. canis and suggests that these dogs were previously infected with E. minasensis. The results of the present study suggest that multiple ehrlichial agents infect dogs in Brazil, which highlights the need to consider different Ehrlichia spp. in Brazilian dogs, particularly in areas where dogs are frequently exposed to multiple tick species. This investigation is the first to provide serologic evidence of E. minasensis infection in dogs from Brazil.