Tick Rhipicephalus Research Articles

Ehrlichia canis rapid spread and possible enzooty in northern South Australia and distribution of its vector Rhipicephalus linnaei.

Recent concerns have arisen in Australia regarding detections of the exotic bacterium Ehrlichia canis which has resulted in ehrlichiosis outbreaks. In Australia, it is spread by the tropical brown dog tick Rhipicephalus linnaei, formerly Rhipicephalus sanguineus sensu lato tropical lineage. Previously, the tick has been recorded in South Australia in the Coober Pedy and the Oodnadatta areas. This study, which includes historical specimens data held in historical Australian arthropod collections, along with 10 sampled remote communities, confirms the wide distribution range of this species within the State. E. canis was detected by PCR in the ticks. The percentage of dogs hosting PCR-positive ticks increased from 2.8% (95% confidence interval [CI]: 0.3 to 9.7) in November-December 2020 to 62.9% (95% CI: 44.9 to 78.5) end of February 2021, initially in two then in seven Anangu Pitjantjatjara Yankunytjatjara lands communities in the far northern regions of South Australia. Our results suggest a rapid spread of the pathogen. No evidence of E. canis was found in nine regional communities. The extended tropical brown dog tick distribution indicates a greater area where E. canis may occur and may require management to minimise the impacts of ehrlichiosis outbreaks. Without the implementation of effective detection and control programs, this extended distribution of R. linnaei is likely to result in the spread of the bacterium to other regions.

Virome of Rhipicephalus ticks by metagenomic analysis in Guangdong, southern China

Tick-borne viruses (TBVs) have increasingly caused a global public health concern. This study collected Rhipicephalus ticks in Guangdong, southern China to identify RNA viruses. Meta-transcriptome analysis revealed the virome in Rhipicephalus ticks, resulting in the discovery of 10 viruses, including Lihan tick virus, Brown dog tick phlebovirus 1 and 2 in the family Phenuiviridae, Mivirus and Wuhan tick virus 2 in the family Chuviridae, Wuhan tick virus 1 in the family Rhabdoviridae, bovine hepacivirus in the family Flaviviridae, Guangdong tick quaranjavirus (GTQV) in the family Orthomyxoviridae, Guangdong tick orbivirus (GTOV) in the family Reoviridae, and Guangdong tick Manly virus (GTMV) of an unclassified family. Phylogenetic analysis showed that most of these TBVs were genetically related to the strains in countries outside China, and GTQV, GTOV, and GTMV may represent novel viral species. These findings provided evidence of the long-distance spread of these TBVs in Guangdong, southern China, suggesting the necessity and importance of TBV surveillance.

Rhipicephalus linnaei (Audouin, 1826) recognised as the “tropical lineage” of the brown dog tick Rhipicephalus sanguineus sensu lato: Neotype designation, redescription, and establishment of morphological and molecular reference

We re-describe the adult stages of Rhipicephalus linnaei (Audouin, 1826), and characterise its diagnostic molecular traits. A male R. linnaei collected in Esna City, Luxor Governorate, Egypt is designated as the neotype. Rhipicephalus linnaei is re-established as a valid tick name and removed from the synonymy list of Rhipicephalus sanguineus (Latreille, 1806). Rhipicephalus linnaei is most similar to R. sanguineus and Rhipicephalus camicasi Morel, Mouchet & Rodhain, 1976 because they share similar elongated comma-like spiracula that are narrowly visible dorsally, and the dorsal prolongation is narrower than the width of the adjacent festoon. The male of R. camicasi is distinguished from R. linnaei by the non-tapering caudal widening of the spiracula. The male of R. sanguineus is distinguished from R. linnaei by shorter extension that does not taper into a long narrow extension of the spiracula. The genital pore atrium of female R. linnaei is broadly U-shaped, while it is a narrower U-shape in R. sanguineus. The remaining species within the R. sanguineus species complex – Rhipicephalus sulcatus Neumann, 1908, Rhipicephalus turanicus Pomerantsev, 1940, Rhipicephalus guilhoni Morel & Vassilades, 1963, Rhipicephalus secundus Feldman-Muhsam, 1952 and Rhipicephalus afranicus Bakkes, 2020, all exhibit spiracula with the dorsal prolongation as wide as the adjacent festoon. The DNA sequence of R. linnaei is most closely related to R. guilhoni. The phylogenetic analysis of mitogenome (mtDNA) sequences including assembled mtDNA from whole genome sequencing of the neotype supports R. linnaei as a well-defined taxon when compared with DNA sequences of other species of the R. sanguineus species complex, in particular: R. sanguineus, R. turanicus, R. secundus and R. camicasi. Molecularly, R. linnaei belongs to the so-called R. sanguineus s.l. "tropical lineage" distributed globally including the Americas, Africa, Europe, Asia and is the only species from R. sanguineus species complex in Australia.

Identification of ectoparasites from domestic pigs of rangamati district

Ectoparasite infestations have direct and indirect negative impacts on its host. Ectoparasite fauna of pigs of Bangladesh is not well documented. Our objective was to detect the ectoparasite fauna among the pigs in Rangamati district of Bangladesh. We examined, 480 pigs from 104 households by close inspection and detected one species of louse (e.g., Haematopinus suis), three species of ticks (Amblyoma testudinarium, Haemaphysalis bispinosa, and Rhipicephalus sanguineus), and one species of flea (Ctenocephalides canis). Pathology and economic losses due to the detected ectoparasites in Rangamati district need further investigation for the betterment of the local pig industry. Bangladesh J. Agri. 2022, 47(1): 88-94

The association of extracts of Achyrocline satureioides and the fungus Beauveria bassiana against the tick Rhipicephalus microplus

The tick Rhipicephalus microplus (Canestrini) is a major economic hurdle to the global livestock industry. The incorrect and indiscriminate control carried out by synthetic chemical compounds has contributed to the emergence of parasite resistance present today to many products available in the veterinary market. Effective, economically viable and potentially safe alternatives need to be investigated, including herbal medicine and biological control by entomopathogenic fungi. In this study, extracts from Achyrocline satureioides (Lam.) DC. obtained by extraction with solvents of different polarities associated and not associated with the entomopathogenic fungus Beauveria bassiana (Balsamo-Crivelli) Vuillemin were evaluated on different stages of the life cycle of R. microplus. The activity of plant extracts, fungus and their associations in ticks was analyzed in vitro through the adult immersion test, larval packet test and larval immersion test. The highest efficacy on engorged females (43.3%) was reached by the hexanic partition (ASh) at 5mg/mL + fungus, reducing larval hatchability. ASh associated with B. bassiana also caused high mortality of larvae, reaching LC50 of 6.23 and 2.65mg/mL in the packet and immersion tests, respectively. The results obtained showed that extracts, when used in combination with the fungus, have their action enhanced, reaching 100% mortality of larvae. Among the evaluated methodologies, it was observed that the larval immersion test allows better assessment, due to the time of contact with the larvae. The results obtained with A. satureioides associated with the fungus are considered promising and open new perspectives for future product development.

Pyrokinin receptor silencing in females of the southern cattle tick Rhipicephalus (Boophilus) microplus is associated with a reproductive fitness cost

BackgroundRhipicephalusmicroplus is the vector of deadly cattle pathogens, especially Babesia spp., for which a recombinant vaccine is not available. Therefore, disease control depends on tick vector control. However, R.microplus populations worldwide have developed resistance to available acaricides, prompting the search for novel acaricide targets. G protein-coupled receptors (GPCRs) are involved in the regulation of many physiological processes and have been suggested as druggable targets for the control of arthropod vectors. Arthropod-specific signaling systems of small neuropeptides are being investigated for this purpose. The pyrokinin receptor (PKR) is a GPCR previously characterized in ticks. Myotropic activity of pyrokinins in feeding-related tissues of Rhipicephalussanguineus and Ixodesscapularis was recently reported.MethodsThe R.microplus pyrokinin receptor (Rhimi-PKR) was silenced through RNA interference (RNAi) in female ticks. To optimize RNAi, a dual-luciferase assay was applied to determine the silencing efficiency of two Rhimi-PKR double-stranded RNAs (dsRNA) prior to injecting dsRNA in ticks to be placed on cattle. Phenotypic variables of female ticks obtained at the endpoint of the RNAi experiment were compared to those of control female ticks (non-injected and beta-lactamase dsRNA-injected). Rhimi-PKR silencing was verified by quantitative reverse-transcriptase PCR in whole females and dissected tissues.ResultsThe Rhimi-PKR transcript was expressed in all developmental stages. Rhimi-PKR silencing was confirmed in whole ticks 4 days after injection, and in the tick carcass, ovary and synganglion 6 days after injection. Rhimi-PKR silencing was associated with an increased mortality and decreased weight of both surviving females and egg masses (P < 0.05). Delays in repletion, pre-oviposition and incubation periods were observed (P < 0.05).ConclusionsRhimi-PKR silencing negatively affected female reproductive fitness. The PKR appears to be directly or indirectly associated with the regulation of female feeding and/or reproductive output in R.microplus. Antagonists of the pyrokinin signaling system could be explored for tick control.Graphical abstract

Preparation of geranium oil formulations effective for control of phenotypic resistant cattle tick Rhipicephalus annulatus

The aim of the present study was to evaluate in vitro and in vivo the acaricidal activity of two forms of geranium (Pelargonium graveolens) (PG). These two forms were the P. graveolens essential oil nanoemulsion (PGN), and the PG in combination with the sesame oil (SO), PGSO). These forms were first evaluated in vitro for their adulticidal, ovicidal, and larvicidal activities against the different stages of acaricide-resistant Rhipicephalus annulatus (Say). Geranium nanoemulsion was prepared and then characterized by UV–Vis spectrophotometer, and zeta droplet size measurement. The results revealed that LC50 of the PG against the adult ticks was attained at concentration of 7.53% while it was decreased to 1.91% and 5.60% for PGSO and PGN, respectively. Also, the LC50 of PGN and PGSO were reached at concentrations of 1.688 and 0.944%, respectively against the larvae while the LC50 of the PG was reached at concentration of 3.435% for. The combination of PGN with PG exhibited non-significant ovicidal effect meanwhile PGSO showed significant ovicidal effect even at the low concentration (2.5%). The PGSO and PGN formulations were applied in a field trial to control the ticks of the naturally infested cattle. PGSO and PGN significantly reduced the tick burden to 74.83% and 87.97%, respectively at 3 weeks post-application with performance better than the deltamethrin (29.88%). In conclusion, the two PG forms can be used as suitable alternatives to control R. annulatus tick and they need further modifications for effective field application.

Assessment of habitat suitability for the cattle tick Rhipicephalus (Boophilus) microplus in temperate areas

The aim of this research was to analyze and model the aptitude of temperate areas to support permanent populations of the cattle tick Rhipicephalus microplus, which is principally distributed in tropical and subtropical areas. This work integrated field-derived data of tick development with temperature and land-based models of tick spread in Argentina. The integrated analysis of the results suggest that approximately 31°S is the southern limit where R. microplus finds appropriate climatic conditions to be established permanently. The establishment of permanent populations of R. microplus south of this latitudinal threshold is currently restricted because the low temperatures in autumn and winter inhibit the development of its eggs, but the introduction of cattle infested with R. microplus from early spring to late summer in temperate areas could produce engorged females laying eggs that would originate viable larvae from late spring to winter. The comparison of the temperature-based maps of habitat suitability with those obtained considering the lands suitable for livestock grazing, clearly shows that the models based only on climatic variables overestimate the potential dispersal of the cattle tick. The outcomes of this study suggest that an increase of temperature in the months of autumn and winter around 2°-2.75 °C should be necessary for the establishment of permanent populations of R. micoplus in the region belonging to temperate areas. This would allow that a tick generation emerged in early spring due to the overwintering of eggs and larvae originated from females detached from cattle during autumn or early winter.

Their young bite better: On- and off-host selection pressure as drivers for evolutionary-developmental modification in Rhipicephalus ticks

Distinct life stages may experience different selection pressures influencing phenotypic evolution. Morphological evolution is also constrained by early phenotypes, since early development forms the phenotypic basis of later development. This work investigates evolutionary-developmental modification in three life stages and both sexes of 24 Rhipicephalus species using phylogenetic comparative methods for geometric morphometrics of basis capituli (basal mouthpart structure used for host attachment), and scutum or conscutum areas (proxy for overall body size). Findings indicate species using large hosts at early life stages have distinct basis capituli shapes, correlated with host size, enabling attachment to the tough skins of large hosts. Host-truncate species (one- and two-host) generally retain these adaptive features into later life stages, suggesting neoteny is linked to the evolution of host truncation. In contrast, species using small hosts at early life stages have lost these features. Developmental trajectories differ significantly between host-use strategies (niches), and correlate with distinct clades. In two-host and three-host species using large hosts at early life stages, developmental change is heterotopically accelerated (greater cell mass development) before the first off-host period where selection probably favours large individuals able to better resist dehydration when questing (waiting) for less abundant, less active hosts. In other species, development is heterotopically reduced (neotenic), possibly because dehydration risk is bypassed by prolonged host attachment (one-host species – heterotopic neoteny), or is allometrically repatterned possibly by using highly abundant and active hosts (three-host species using small hosts at early life stages – allometric repatterning). These findings highlight complex trade-offs between on- and off-host factors of free-living ectoparasite ecology, which mediate responses to diverse selection pressures varied by life stage and host-use strategy. It is proposed that these trade-offs shape evolutionary-developmental morphology and diversity of Rhipicephalus ticks.

Evaluation of Repellency of Stop the Bites® Botanical Pesticide to White-Tailed Deer at Corn Feeders

Stop the Bites® botanical pesticide was evaluated for repellent properties against white-tailed deer, Odocoileus virginianus (Zimmerman), at feeders with supplemental corn, Zea mays L., in Cameron County, Texas. The pesticide was tested as a ground treatment around feeders and as spray applied directly to deer as they consumed corn at supplemental feeders. With either treatment, there was no significant difference in numbers of white-tailed deer at the feeders compared to the paired nontreated check. The botanical pesticide may be useful for treatment of cattle fever ticks (Rhipicephalus microplus (Canestrini) and Rhipicephalus annulatus (Say)) on deer at supplemental corn feeders during the hunting season when ivermectin-treated corn is withdrawn, or for treatment using a remotely operated sprayer at fence crossings for tick-infested nilgai, Boselaphus tragocamelus (Pallas).

Enzymatic synthesis of geranyl acetate in batch and fed-batch reactors and evaluation of its larvicidal activity against Rhipicephalus (Boophilus) microplus

Geraniol esters, such as geranyl acetate, are known to have antimicrobial and insect-repellent action, but their acaricidal activity has been little explored. This study aimed to investigate the solvent-free synthesis of geranyl acetate in batch (BSTR) and fed-batch (FBSTR) stirred tank reactors using the immobilized lipases NS 88011 and Novozym 435 and evaluate its larvicidal activity against the cattle tick Rhipicephalus (Boophilus) microplus. A central composite design (CCD) was used to maximize the synthesis of geranyl acetate in a BSTR. The independent variables were temperature reaction (40–60 °C), acetic acid/geraniol molar ratio (1:1–1:3), and enzyme loading (1–5% w/w in relation to the substrates). Novozym 435 yielded the best results, achieving 99% of geranyl acetate conversion using 1:3 acetic acid/geraniol molar ratio, 60 °C and 5% (w/w) of enzyme loading after 1 h of reaction in a BSTR. In the FBSTR system, a high content of geranyl acetate was obtained (about 80%) in 4 h of reaction using a 1:1 acetic acid/geraniol molar ratio, 60 °C and 5% (w/w) Novozym 435. Geranyl acetate showed potential as an acaricide, with an LC90 of 6.25 mg/mL and 100% mortality at a concentration of 12.5 mg/mL.

Diversity and distribution of ectoparasite taxa associated with Micaelamys namaquensis (Rodentia: Muridae), an opportunistic commensal rodent species in South Africa.

South Africa boasts a rich diversity of small mammals of which several are commensal and harbour parasites of zoonotic importance. However, limited information is available on the parasite diversity and distribution associated with rodents in South Africa. This is particularly relevant for Micaelamys namaquensis (Namaqua rock mouse), a regionally widespread and locally abundant species that is often commensal. To address the paucity of data, the aims of the study were to record the ectoparasite diversity associated with M. namaquensis and develop distribution maps of lice and mites associated with M. namaquensis and other rodents in South Africa. Micaelamys namaquensis individuals (n = 216) were obtained from 12 localities representing multiple biomes during 2017–2018. A total of 5591 ectoparasites representing 5 taxonomic groups – fleas, lice, mesostigmatid mites, chiggers and ticks was recorded. These consisted of at least 57 taxa of which ticks were the most speciose (20 taxa). Novel contributions include new host and locality data for several ectoparasite taxa and undescribed chigger species. Known vector species were recorded which included fleas (Ctenocephalides felis, Dinopsyllus ellobius and Xenopsylla brasiliensis) and ticks (Haemaphysalis elliptica, Rhipicephalus appendiculatus and Rhipicephalus simus). Locality records indicate within-taxon geographic differences between the 2 louse species and the 2 most abundant mite species. It is clear that M. namaquensis hosts a rich diversity of ectoparasite taxa and, as such, is an important rodent species to monitor in habitats where it occurs in close proximity to humans and domestic animals.

New field technique to evaluate the action of the fungus Metarhizium anisopliae on Rhipicephalus (Boophilus) microplus tick

The tick Rhipicephalus microplus parasitizes cattle and transmits infectious agents, thus generating losses estimated at US$ 3.24 billion per year. Although chemical treatment is the main means of control, there are records of populations resistant to these products in several regions of Brazil. The losses associated with production animals and resistance to acaricides have given rise to searching for alternative control strategies. The entomopathogenic fungus Metarhizium anisopliae is a promising biological control agent. The objective of this work was to evaluate the action of the fungus M. anisopliae for controlling R. microplus, using a novel semi-field test protocol. The experiment began with application of a solution of M. anisopliae (isolate IBCB 425) at a concentration of 2 × 1013 conidia/hectare, to the soil. The broth containing the fungus was made up of water and mineral oil in the proportions of 19:1. The same broth was applied without addition of fungus in the control group. Females of R. microplus were placed on the soil, wrapped in voile fabric, in both plots. The groups were left in the pasture for 15 days, after which they were collected and kept in a BOD chamber for the end of incubation and hatching. Identical deposition was repeated three times every 14 days for both groups in the same areas. Engorged females of both groups were evaluated in relation to fungal infection, in histological sections that were then stained with hematoxylin and eosin (HE) and by means of in situ hybridization with oligonucleotides labeled with biotin. The results showed that the effectiveness of the fungus continued even beyond 30 days after application. This suggested that the colonization of the pasture by the fungus was stable. HE staining and in situ hybridization showed, respectively, changes to the reproductive system of the females and confirmation of infection by the species M. anisopliae. Based on these results, it is possible to demonstrate the action of this entomopathogen on the tick and suggested that the field markers technique can be used and replicated to evaluate the action of the fungus M. anisoplie in females of R. microplus.

Possible Association between Selected Tick-Borne Pathogen Prevalence and Rhipicephalus sanguineus sensu lato Infestation in Dogs from Juarez City (Chihuahua), Northwest Mexico-US Border.

Tick-borne bacterial pathogens (TBBPs) show a worldwide distribution and represent a great impact on public health. The brown dog tick (Rhipicephalus sanguineus) is a vector of several pathogens that affect dogs and sometimes humans as well. In addition, TBBPs represent a diagnostic challenge and imply financial resources and medical treatment for long periods of time. In the present study, R. sanguineus s. l. was identified as the main tick species naturally parasitizing dogs that inhabit. Juárez City, Chihuahua, in the Paso del Norte region, Mexico–US Border, representing 99.8% of the cases. Additionally, an end-point PCR was performed to search for whether pathogens in R. sanguineus s. l. can transmit in DNA extracted from ticks and dog blood samples. This is the first molecular detection of Rickettsia rickettsi infecting domestic dogs in Mexico; however, other pathogens were also identified, such as Ehrlichia canis and Anaplasma platys in both ticks and dog blood samples, while Anaplasma phagocytophilum was identified only in dog blood samples. Moreover, co-detection in tick pools and co-infection in the analyzed dog blood samples could be found. Similarly, this research showed that dogs were found mostly parasitized by adult female ticks, increasing the possibility of transmission of E. canis.

Testing a multi‐factorial model of the role of Rhipicephalus sanguineus in the spread of Rocky Mountain Spotted Fever in the Arizona region

Rocky Mountain Spotted Fever (RMSF) is the deadliest tick‐borne disease in the United States. RMSF is spread from a canine host to humans through incidental contact with a tick vector. Historically, transmission of R. rickettsii, the causative agent, has been associated with the American dog tick (Dermacentor variabilis) and the Rocky Mountain wood tick (Dermacentor andersoni). However, in 2003, an outbreak of RMSF in Arizona was associated with a novel vector, the brown dog tick (Rhipicephalus sanguineus). Since then, the vectoring capacity of the brown dog tick has spread across the American Southwest and into parts of Mexico. Currently, the brown dog tick is not known to vector the bacteria outside of this area despite brown dog ticks being present in every state in the U.S. If this vectoring capacity continues to expand, many parts of the country will be at risk due to the brown dog tick’s ubiquitous nature. This is especially alarming as failure to treat RMSF in humans within the first five days of infection can lead to mortality rates as high as 80%. Therefore, this research was aimed at determining the factors that are currently limiting the vectoring capacity of the brown dog tick to Arizona and the surrounding region in order to prevent further spread of RMSF.The results of our research show that the current spread of RMSF in the Arizona region is due to a combination of four factors: (1) the presence of a distinct population of brown dog ticks, (2) variation in the genetic strain of the causative agent R. rickettsii, (3) distribution of canine seroprevalence across the region, and (4) geographic and climatic factors. In support of this, we have identified three genetically distinct clades of brown dog tick across the region that vary in the R. rickettsii infection rate. In sequencing intergenic regions of the R. rickettsii isolated from these tick populations, we have identified variation in the rickettsial strain across the region. Using immunofluorescence assays, we determined that canine seroprevalence rates are rising and seropositive dogs were found in regions that have previously not reported any human cases including regions as far north as Petaluma, CA. Even more concerning, 14 of 16 counties surveyed were at medium to high risk for human outbreak. These data were then analyzed at a county level and the relative role of each of the factors varied by geographic location. Together, this multi‐factorial model is a first step towards understanding the epidemiology of RMSF in the Arizona region and provides insights into ways to improve human and canine health by stopping future spread of RMSF.

Rhipicephalus annulatus, R. australis or R. microplus? Discordance between morphological and genetic data among three cattle tick species.

The taxonomy of ticks of the subgenus Boophilus has been extensively debated and is often complicated by the high intraspecific variation of morphological features between species. Notably, the cattle tick Rhipicephalus microplus is a species complex consisting of Rhipicephalus annulatus, Rhipicephalus australis and the three mitochondrial clades (A-C) of R. microplus. To gain insight into the taxonomic status of this species complex, we performed morphological and molecular analyses on these cattle ticks across four states in peninsular Malaysia. We morphologically identified 60 males and 104 females of R. microplus, 298 males and 374 females of R. australis, and one R. annulatus male in our field collection, of which the latter two species have never been recorded in Malaysia. However, all three morphologically identified species were molecularly assigned as R. microplus clade A based on the barcoding cytochrome oxidase subunit I (COI) analysis. The discrepancy between morphological and genetic data highlights an urgent need for further exploration and in-depth research into the taxonomic status of these sympatric tick species.

Hematological alterations in dogs infected with Erlichia canis

The hemoparasite Erlichia canis, a Gram-negative bacterium of the order Rickettsiales and genus Erlichia spp., is an obligate intracellular parasite with tropism for mononuclear leukocytes. Transmitted through inoculation by the tick Rhipicephalus sanguineus. Upon entering the leukocytes to which it has tropism, the bacteria form clusters called morulae. The disease has three phases, acute, subclinical and chronic. The study used samples of blood or blood serum from 127 dogs, collected by venipuncture of the radial and jugular veins. After the analysis, it was possible to observe that the most commonly found alterations were eosinopenia (48.41%), thrombocytopenia (75%) and non-regenerative anemia (50%) being morphologically classified mostly as hypochromic normocytic. Concluding that the predominant hematological findings, even if unspecific and individual for each animal, were those mentioned above.

Molecular targets for the development of new acaricides against Rhipicephalus microplus: a review.

The cattle tick Rhipicephalus microplus is an ectoparasite with high economic importance to bovine culture, mainly in tropical and subtropical regions. The resistance of the tick from the commercial acaricides has hindered its control, thus motivating the search for new strategies. The purpose of this study was to perform a critical review about the main molecular targets of R. microplus that are useful for the discovery of new acaricides. Bibliographic search was conducted in the databases PubMed, ScienceDirect and CAB Direct, using the following descriptors: ‘Rhipicephalus microplus’, ‘Boophilus microplus’, ‘molecular targets’ and ‘action’, published between 2010 and 2021. Out of the 212 publications identified, 17 articles were selected for study inclusion. This review described 14 molecular targets and among these 4 are targets from commercial acaricides. Most of them are enzymes to catalyse important reactions to tick survival, related to energetic metabolism, mechanisms of biotransformation and neurotransmission. The data will be helpful in the development of new more effective and selective acaricides.

Babesiosis in cattle and ixodid tick distribution in Dasenech and Salamago Districts, southern Ethiopia

Babesiosis, caused by protozoan parasites of the genus Babesia, and ixodid ticks are considered to be one of the most important causes that result in significant economic losses in cattle production worldwide, including in Ethiopia. A cross-sectional study was undertaken in the Dasenech and Salamago Districts of South Omo zone Ethiopia to determine the prevalence and associated risk factors of babesia infection and ixodid ticks of cattle using Giemsa-stained thin and thick film techniques and morphological identification keys for babesia species and tick identification, respectively. Out of 470 examined cattle, 102 (21.7%) were infected by Babesiosis (15.53% Babesia bigemina and 6.17% Babesia bovis). A statistically significant association (p < 0.05) was observed between babesia infection and season and tick infestation. However, cattle that were infected with the Babesia parasite revealed a lower mean PCV value (21.49%) than noninfected cattle (28.29%) and showed a statistically significant (p < 0.05) difference with the occurrence of Babesia infection. The overall prevalence of ixodid ticks was 53.8% (253/470) and revealed a statistically significant association (p < 0.05) between the season and origin of the animal. However, no statistically significant association (p > 0.05) was observed between sex, age, and body condition score of the animal with the occurrence of ixodid tick. A total of 8040 adult ticks belonging to four tick genera, Amblyomma, Rhipicephalus (Boophilus), Hyalomma, and Rhipicephalus, were collected from various body parts and identified. The high prevalence of Babesia infection and ixodid ticks in cattle at the study sites requires seroprevalence and molecular studies to identify the predominant Babesia species and to detect Babesia in tick hemolymph for the identification of tick genera responsible for the occurrence of Babesia infection. Additionally, tailoring suitable and coordinated tick management methods using chemotherapy as well as strategic treatment to overt clinical cases of bovine babesiosis is critical.

Molecular Characterization of Rickettsial Agents in Ticks (Acari: Ixodidae) from Sri Lanka.

ABSTRACT.Because the majority of spotted fever group rickettsiae are transmitted to humans by tick bites, it is important to understand which ticks might play a role in transmission of rickettsial pathogens in Sri Lanka. The purpose of our study was to conduct molecular surveillance of 847 ticks collected in different locations in central Sri Lanka to determine which were infected with Rickettsia and Anaplasmataceae. Molecular methods were used to identify the ticks and the agents detected. Most ticks (Amblyomma, Haemaphysalis, and Rhipicephalus) were collected by flagging, and lower number was collected from dogs, cattle, pigs, a pangolin, and tortoises. Five spotted fever genotypes were identified: a Rickettsia africae-like agent in Amblyomma larvae, Rhipicephalus massiliae and a related genotype identified in association with the tropical type of Rhipicephalus sanguineus from dogs and Rhipicephalus haemaphysaloides from dogs and cattle, and Candidatus R. kellyi and another novel genotype (SL94) in R. haemaphysaloides. Twenty-three ticks were positive for Anaplasmataceae, including one Anaplasma and two Ehrlichia genotypes. Because the sequence database for both ticks and rickettsial agents from Sri Lanka and southern India is not extensive, additional molecular characterization of the tick species of Sri Lanka and their rickettsial agents is required to understand their pathogenic potential more completely. However, several of the agents we identified in this survey may well be pathogenic for humans and domestic animals, and should be considered as a part of epidemiological surveillance and patient management.