Amblyomma Variegatum Research Articles

In vitro acaricidal activity of Bobgunnia madagascariensis Desv. against Amblyomma variegatum (Fabricius) (Acari: Ixodidae).

The objective of the study was to determine the acaricidal properties of Bobgunnia madagascariensis (Desv.) J.H. Kirkbr. and Wiersema (Leguminosae) against adult Amblyomma variegatum (Fabricius) ticks, using Tephrosia vogelii Hook.f. (Leguminosae) as a positive control. Plant extracts of both were prepared using methanol, acetone and chloroform as extraction solvents. Methanol leaf extracts of T. vogelii (0.014 g) and methanol fruit extracts of B. madagascariensis (0.0062 g) gave the highest mean extraction weights among the plant parts and solvents used. In free contact bioassays, only methanol extracts of the bark and leaf material of T. vogelii and methanol fruit extracts of B. madagascariensis produced 100 % mortality of A. variegatum ticks in 24 h. The acaricidal activity of methanol leaf extracts of T. vogelii persisted for up to 8 days while that of fruit extracts of B. madagascariensis persisted for only 6 days. In topical application bioassays, the toxicity of T. vogelii and B. madagascariensis extracts was found to be significantly different at 95 % confidence level, with B. madagascariensis extracts (LD50 0.030 w/v) being more toxic than T. vogelii extracts (LD50 0.555 w/v). This study has shown that plant extracts of B. madagascariensis and T. vogelii extracts have significant in vitro acaricidal activity against A. variegatum ticks and can thus be considered as alternatives for tick control. Further research is however required on persistence, safety and the required application rates.

Multiple Pathogens Including Potential New Species in Tick Vectors in Côte d'Ivoire.

BackgroundOur study aimed to assess the presence of different pathogens in ticks collected in two regions in Côte d’Ivoire.Methodology/Principal FindingsReal-time PCR and standard PCR assays coupled to sequencing were used. Three hundred and seventy eight (378) ticks (170 Amblyomma variegatum, 161 Rhipicepalus microplus, 3 Rhipicephalus senegalensis, 27 Hyalomma truncatum, 16 Hyalomma marginatum rufipes, and 1 Hyalomma impressum) were identified and analyzed. We identified as pathogenic bacteria, Rickettsia africae in Am. variegatum (90%), Rh. microplus (10%) and Hyalomma spp. (9%), Rickettsia aeschlimannii in Hyalomma spp. (23%), Rickettsia massiliae in Rh. senegalensis (33%) as well as Coxiella burnetii in 0.2%, Borrelia sp. in 0.2%, Anaplasma centrale in 0.2%, Anaplasma marginale in 0.5%, and Ehrlichia ruminantium in 0.5% of all ticks. Potential new species of Borrelia, Anaplasma, and Wolbachia were detected. Candidatus Borrelia africana and Candidatus Borrelia ivorensis (detected in three ticks) are phylogenetically distant from both the relapsing fever group and Lyme disease group borreliae; both were detected in Am. variegatum. Four new genotypes of bacteria from the Anaplasmataceae family were identified, namely Candidatus Anaplasma ivorensis (detected in three ticks), Candidatus Ehrlichia urmitei (in nine ticks), Candidatus Ehrlichia rustica (in four ticks), and Candidatus Wolbachia ivorensis (in one tick).Conclusions/SignificanceFor the first time, we demonstrate the presence of different pathogens such as R. aeschlimannii, C. burnetii, Borrelia sp., A. centrale, A. marginale, and E. ruminantium in ticks in Côte d’Ivoire as well as potential new species of unknown pathogenicity.

Evaluation of Amitraz and Diazinon against Rhipicephalus decoloratus and Amblyomma variegatum in Bako Agricultural Research Center

Ticks are blood feeding ectoparasites that induce huge production losses in livestock industry and creating serious public health problems in the world. Although the use of chemicals is still the most effective method of tick control, uncontrolled applications may have accelerated the emergence of tick resistance to several active ingredients available. This study was conducted to assess the efficacy of commonly used acaricides (amitraz and diazinon) against Rhipicephalus decoloratus and Amblyomma variegatum collected from cattle by using Adult immersion test method. The in-vitro test employed an adult immersion technique. For laboratory experiment, adult ticks collected were exposed to Amitraz or Diazinon. The in-vitro assay showed no statistically significant tickicidal difference (p>0.05) between these compounds, although amitraz proved a relatively better efficacy. For both acaricides, doubled concentration was more effective in tick killing. In conclusion, comparing the efficacy of the two acaricides, amitraz is the preferable one. Furthermore, right application and choice of acaricides, avoidance of uncontrolled utilization of commercial insecticides and Strategies involving the early detection of resistance needs to be pursued in order to avoid any resistance against ticks in cattle.

Management of Cattle Parasitism and Use of Anthelmintics in Mixed Farming Systems in the Vina Division, Cameroon

In order to assess cattle parasitism management and use of anthelmintics, a questionnaire was administered to randomly selected farmers and veterinarians. Analysis of faecal samples and haemoparasites, and entomological survey were performed. Worm infestations, ectoparasites, infectious diseases and trypanosomosis were major diseases. Helminths control included mainly de-worming using levamisole, ivermectin and albendazole. Faecal egg counts (FEC) showed strongyle-type eggs (75%), Strongyloides papillosus (5%), Trichuris ovis (2%), Toxocara vitullorum (3%). Oocytes, especially Eimeria spp (10%) were present. 2.8% of 107 cattle investigated were positive for Trypanosoma congolense, with lowest Packed Cells Volume, suggesting that farmers may treat animals against trypanosomes without the help of a veterinarian. Ticks included Amblyomma variegatum (29.6%), Hyalomma spp (37.0%), Boophilus spp (29.6 %) and Rhippicephalus spp (3.7%). They were males (40.7%), females (38.9%) and nymphs (20.4%). Since many factors were important predictors of FEC and others such as education of farmers, nutrition, grazing system and control through anthelmintics accounted, these factors should be included in the drawing up of a control program against parasitic diseases.

Haematological response of Sokoto Gudali heifers to Babesia infection and tick control measures in a humid tropical environment

Sixteen Sokoto Gudali heifers weighing 184±16 kg were used to assess the haematological response of zebu cattle to babesia infection under different tick control measures. Animals were grazed inside tick-infested pastures and subjected to different cypermethrin treatments as follows: no treatment/control (NT); treatment of animal (TA); treatment of pasture (TP) and treatment of animal and pasture (TAP). Tick count and babesia infection in blood were assessed at 21-day intervals. Erythrocyte sedimentation rate (ESR), packed cell volume (PCV), haemoglobin (Hb), red blood cell (RBC) and white blood cell (WBC) count were also determined in the animals at pre-treatment and post-treatment periods. Tick species found on the animals include Amblyomma variegatum (8.6 %), Boophilus decoloratus (25.2 %) and Boophilus geigyi (66.2%). Tick count reduced from an average of 34 to less than 8 by the 12th week of study. Babesia parasite (Babesia bigemina) was not detected in the blood of treated animals by the 6th week. The ESR of heifers at the 12th week was 8.36, 2.10, 2.65, 1.65 mm/h; RBC, 6.05, 8.20, 8.26, 9.30 x 1012/L; and WBC, 12.37, 6.06, 7.08, 4.89 x 109/L for NT, TA, TP. and TAP respectively. The ESR and WBC values obtained shows that infection rates increased in untreated animals and decreased in animals under tick control measures. The RBC count also indicates improvement in health status of heifers when cypermethrin treatments were applied regularly. Babesia bigemina

Identification and characterization of a cathepsin L-like cysteine protease from Rhipicephalus (Boophilus) annulatus.

The tick Rhipicephalus (Boophilus) annulatus is one of the most important ectoparasites of bovines and is responsible for the transmission of different pathogens such as Babesia and Anaplasma. Cysteine proteases are involved in several host-tick interactions including invasion of host tissues, immune evasion, pathogen transmission, embryogenesis and blood digestion. In this study, the gene encoding R. annulatus cathepsin L-like enzyme (RaCL1) was cloned into pTZ57R/T vector, sequenced and analyzed using bioinformatics approaches. The nucleotide length of RaCL1 was 999 bp. Bioinformatics analysis showed 332 amino acids with an approximate molecular weight of 36.3 kDa which contained a signal peptide sequence (18 amino acids), pro-region (97 amino acids) and mature enzyme (217 amino acids). Multiple sequence alignment of the RaCL1 revealed high similarity to cathepsin L-like cysteine proteases from other tick species such as Rhipicephalus (Boophilus) microplus and Amblyomma variegatum. Based on bioinformatics analyses, results of this work suggest that RaCL1 can be a suitable candidate for the development of vaccine against R. annulatus.

Parapatric distribution and sexual competition between two tick species, Amblyomma variegatum and A. hebraeum (Acari, Ixodidae), in Mozambique.

BackgroundAmblyomma variegatum and A. hebraeum are two ticks of veterinary and human health importance in south-east Africa. In Zimbabwe they occupy parapatric (marginally overlapping and juxtaposed) distributions. Understanding the mechanisms behind this parapatry is essential for predicting the spatio-temporal dynamics of Amblyomma spp. and the impacts of associated diseases. It has been hypothesized that exclusive competition between these species results from competition at the levels of male signal reception (attraction-aggregation-attachment pheromones) or sexual competition for mates. This hypothesis predicts that the parapatry described in Zimbabwe could also be present in other countries in the region.MethodsTo explore this competitive exclusion hypothesis we conducted field surveys at the two species’ range limits in Mozambique to identify areas of sympatry (overlapping areas) and to study potential interactions (communicative and reproductive interference effects) in those areas. At sympatric sites, hetero-specific mating pairs were collected and inter-specific attractiveness/repellent effects acting at long and short distances were assessed by analyzing species co-occurrences on co-infested herds and co-infested hosts.ResultsCo-occurrences of both species at sampling sites were infrequent and localized in areas where both tick and host densities were low. At sympatric sites, high percentages of individuals of both species shared attachment sites on hosts and inter-specific mating rates were high. Although cross-mating rates were not significantly different for A. variegatum and A. hebraeum females, attraction towards hetero-specific males was greater for A. hebraeum females than for A. variegatum females and we observed small asymmetrical repellent effects between males at attachment sites.ConclusionsOur observations suggest near-symmetrical reproductive interference between A. variegatum and A. hebraeum, despite between-species differences in the strength of reproductive isolation barriers acting at the aggregation, fixation and partner contact levels. Theoretical models predict that sexual competition coupled with hybrid inviability, greatly reduces the probability of one species becoming established in an otherwise suitable location when the other species is already established. This mechanism can explain why the parapatric boundary in Mozambique has formed within an area of low tick densities and relatively infrequent host-mediated dispersal events.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-1116-7) contains supplementary material, which is available to authorized users.

Resistance status of ticks (Acari; Ixodidae) to amitraz and cypermethrin acaricides in Isoka District, Zambia.

This study was designed to obtain data on the farmer's approach to tick control and to determine whether Rhipicephalus appendiculatus Neuman, Amblyomma variegatum (Fabricius), and Rhipicephalus (Boophilus) microplus (Canestrini) were resistant to amitraz and cypermethrin acaricides, in Isoka District, Zambia. Prevailing tick control practices were documented by administering a semi-structured questionnaire to 80 randomly selected smallholder livestock farmers from four agricultural camps (Longwe, Kantenshya, Kapililonga, and Ndeke) in Isoka District. Modified larval packet test (LPT) bioassay experiments were used to determine the resistance status of the common tick species against amitraz and cypermethrin acaricides. Fifty percent of respondents practiced chemical tick control with amitraz (27%) and cypermethrin (23%) being the acaricides in use, and were applied with knapsack sprayers. Less than 3l of spray wash per animal was used which was considerably lower than the recommended delivery rate of 10l of spray wash per animal. No significant susceptibility change to amitraz at 95% confidence level was observed in R. appendiculatus and A. variegatum against amitraz. However, a significant change in the susceptibility of R. (Bo.) microplus tested with amitraz was detected at 95% confidence. The test population had a lower susceptibility (LD50 0.014%; LD90 0.023%) than the reference population (LD50 0.013%; LD90 0.020%). The results indicated that resistance to amitraz was developing in R. (Bo.) microplus. For cypermethrin, no significant susceptibility change at 95% confidence was observed in any of the three species and thus resistance to this chemical was not observed.

High detection rate of Rickettsia africae in Amblyomma variegatum but low prevalence of anti-rickettsial antibodies in healthy pregnant women in Madagascar

Tick-borne spotted fever group (SFG) rickettsioses are emerging infectious diseases in Sub-Saharan Africa. In Madagascar, the endemicity of tick-borne rickettsiae and their vectors has been incompletely studied. The first part of the present study was conducted in 2011 and 2012 to identify potential anthropophilic tick vectors for SFG rickettsiae on cattle from seven Malagasy regions, and to detect and characterize rickettsiae in these ticks. Amblyomma variegatum was the only anthropophilic tick species found on 262 cattle. Using a novel ompB-specific qPCR, screening for rickettsial DNA was performed on 111 A. variegatum ticks. Rickettsial DNA was detected in 96 of 111 ticks studied (86.5%). Rickettsia africae was identified as the only infecting rickettsia using phylogenetic analysis of ompA and ompB gene sequences and three variable intergenic spacers from 11 ticks. The second part of the study was a cross-sectional survey for antibodies against SFG rickettsiae in plasma samples taken from healthy, pregnant women at six locations in Madagascar, two at sea level and four between 450 and 1300m altitude. An indirect fluorescent antibody test with Rickettsia conorii as surrogate SFG rickettsial antigen was used. We found R. conorii-seropositives at all altitudes with prevalences between 0.5% and 3.1%. Our results suggest that A. variegatum ticks highly infected with R. africae are the most prevalent cattle-associated tick vectors for SFG rickettsiosis in Madagascar. Transmission of SFG rickettsiosis to humans occurs at different altitudes in Madagascar and should be considered as a relevant cause of febrile diseases.

Identification of tick species and disseminate pathogen using hemolymph by MALDI-TOF MS

BackgroundMatrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) is increasingly emerging tool for identification of arthropods including tick vectors using whole or body part of specimens. The challenges of the present study were to assess MALDI-TOF MS profiling for the both identification of tick species and Rickettsia spp. in infected ticks using hemolymph as protein mixture. MethodsFirstly, hemolymph protein mixture from legs of 5 tick species, Rhipicephalus sanguineus, Rhipicephalus bursa, Dermacentor marginatus, Hyalomma marginatum rufipes and Amblyomma variegatum infected by Rickettsia africae were submitted to MALDI-TOF MS to assess tick species identification ability. Secondly, hemolymph MS spectra from Rh. sanguineus infected or not by Rickettsia c. conorii were compared to detect protein profiles changes. Finally, leg hemolymph MS spectra from new specimens of the 5 tick species were tested blindly including ticks infected by R. c. conorii. Discriminating mass peaks distinguishing the R. c. conorii infected and non-infected Rh sanguineus were determined. ResultsConsistent and reproducible MS profiles were obtained into each tick species. Comparison of MS spectra revealed distinct hemolymph protein profiles according to tick species. MS spectra changes were observed between hemolymphs from R. c. conorii-infected and non-infected Rh. sanguineus specimens, revealing 17 discriminating mass peaks. Clustering analysis based on MS protein profiles highlighted that hemolymph samples were grouped according to tick species. All tick hemolymph samples blindly tested against our home-made arthropod MS reference database were correctly identified at the species distinguishing also R. c. conorii-infected from Rickettsia-free Rh. sanguineus specimens. ConclusionThe present study demonstrated the use of hemolymph MS profiles for dual identification of tick species and associated pathogens. This concomitant identification could be helpful for tick entomological diagnosis, notably for specimens removed directly on patients.

In Vitro effect of the ethanolic extract of Tephrosia Vogelii on Rhipicephalus Sanguineus in Abomey-Calavi.

Ticks are vectors of several diseases, of which many are zoonosis transmissible to humans. The use of Tephrosia leafs' extract as a low cost acaricide is spreading among farmers in central Kenya. The present study's aim is to inventory endogenous control methods against dogs' ticks among which Rhipicephalus sanguineus, in the Municipality of Abomey-Calavi. From September to October 2013, a survey was made on forty randomly selected breeders and ticks samples were collected on forty dogs. The web platform, www.epicollect.net, was used for the survey. In total, 77.5% (n=40) of examined dogs were infested with ticks. Three species of ticks were identified: Rhipicephalus sanguineus, Haemaphysalis leachi, and Amblyomma variegatum. They were found on 77.5%, 17.5%, and 15% of examined dogs, respectively. The numerical abundance of the three species was 87.06%, 11.9%, and 1.03%, respectively. The average number of ticks per animal was 16.83±5.04, 2.3±1.64, and 0.2±0.08 for Rhipicephalus sanguineus, Haemaphysalis leachi, and Amblyomma variegatum, respectively. Farmers used manual diptank (67.5%), plant ash (37.5%), petroleum (12.5%), motor oil (2.50 %), and sea water (7.5%) to fight against ticks. The phytochemical screening of the leafy stem's powder of Tephrosia vogelii revealed the presence of catechol tannins, saponins, sugars, leuco-anthocyanins, polyterpenes, and sterols. A 100% larval mortality was observed at the concentration of 20% the ethanolic extract of the leafy stem of Tephrosia vogelii. The LC50 of this ethanolic extract against Rhipicephalus sanguineus larvae was equal to 2.6%.

Canine vector-borne infections in Mauritius.

BackgroundCanine vector-borne diseases have a worldwide distribution, but to the best of our knowledge, no research has been carried out to evaluate their presence on the Indian Ocean island of Mauritius. An investigation into canine vector-borne infections was conducted in dogs (n = 78) resident at an animal shelter in Port Louis, Mauritius using a combination of traditional microscopy and serological methods.MethodsTicks were manually collected from the stray dog population for identification as well as for quantifying tick burdens. Blood was also collected from each dog via either the jugular vein or the cephalic vein, and was stored in EDTA tubes. The stored blood was then used to measure PCV values, make blood smears for the identification of parasites, and used for serological testing of vector-borne disease.ResultsA total of 178 ticks were collected from 52 dogs and identified as Rhipicephalus sanguineus (175/178) or Amblyomma variegatum (3/178). Twenty-six (33%; 95% CI 23, 45) dogs were seropositive for Ehrlichia spp., and 12 (15%; 95% CI 8, 25) for Anaplasma spp., Dirofilaria antigen was detected in 14 (18%; 95% CI 10, 28), and nine (12%; 95% CI 5, 21) dogs had Hepatozoon canis gamonts observed in blood films during microscopic examination. Eleven (14%; 95% CI 7, 24) dogs were co-infected with two pathogens. Borrelia burgdorferi antibodies were not detected in any dogs.ConclusionsInfection with these pathogens had no significant effect on the packed cell volume (PCV), but high tick burdens were significantly associated with the presence of a tick-borne pathogen. This is the first study of its kind on the dog population in Mauritius and demonstrates the presence of previously undocumented canine vector-borne infections on the island. The relatively high proportion of infected dogs within the study should alert clinicians to the presence of canine vector-borne diseases on the island of Mauritius.

English

A cross sectional study was carried out from October 2013 to March 2014 in and around Bishoftu town with the objectives of determining the prevalence of major external parasite species of calves, preferred predilection sites and determine the associated risk factors. The calves were selected randomly from small holder farms in and around the town. According to this study; out of 384 calves observationally examined, and identified using stereomicroscope/hand lenses, 126(32.8%) were found infested with one or more ectoparasites species. The major ectoparasites identified were lice 26.8% followed by ticks 13.5% and mites 0.5%. Overall, three genera and one subgenus of tick comprising five species and one species of lice and one species of mite were identified in the study. Among the ticks, Rhipicephalus (Boophilus) decoloratus (7.6%), Amblyomma variegatum (5.2%) and Rhipicephalus evertsi evertsi (2.9%) were the most prevalent and the least identified tick species was Rhipicephalus pulchelus (0.5%). In this study, Linognathus vituli was the solitary species of lice identified and the prevalent (26.8%) among all ectoparasite identified. With regard to mites, Psoroptus ovis was the only mite species identified with a prevalence of 0.5%. The difference in the prevalence of ectoparasite species in male and female calves was not statistically significant (p>0.05). There was significant (p 0.05). This study demonstrates that ectoparasites are among the most important health constraints of calves in and around Bishoftu leading to important economic losses and attention should be given to control interventions, developing the knowledge of the farmers and further study on the burden of ectoparasites and their effects on calves was recommended. Key words: Bishoftu, calf, ectoparasite, prevalence, small holder farms.

An update on the ecological distribution of the Ixodidae ticks in Zimbabwe.

In total 7657 ticks were collected from 121 dip tanks in 12 districts representative of Zimbabwe's five ecological regions between September 2013 and May 2014. Based on morphological traits four genera and 13 species of ticks were identified. Amblyomma hebraeum (60.3%), Rhipicephalus microplus (58.7%), Rhipicephalus decoloratus (47.1%), Rhipicephalus appendiculatus (56.2%), Rhipicephalus evertsi evertsi (67.8%), Rhipicephalus (near) punctatus (13.2%), Hyalomma truncatum (38%) and Hyalomma rufipes (46.3%) were found in all the ecological regions of the country. Amblyomma variegatum and Rhipicephalus compositus (0.8%) were only found in the north central part of the country while Rhipicephalus simus (5%) had a sparse distribution. The Haemaphysalis leachi group (1.7%) and Rhipicephalus sanguineus (1.7%) were found whenever dogs were sampled suggesting these could be widespread throughout the country. The study confirmed the continued limited distribution of A. variegatum (3.3%) in the north central parts of the country, whereas A. hebraeum was found to have a wide distribution also encroaching areas of high rainfall and lower temperatures where it was not previously recorded. A parapatric relationship existed between these two Amblyomma species. Rhipicephalus appendiculatus was also widely distributed although its presence was dominant in the cooler and wetter parts of the country. The traditionally held view that Hyalomma species and R. evertsi evertsi can survive well under diverse conditions is upheld in this study. Rhipicephalus microplus was also present in dry regions but its adaptability to these regions requires further investigation.

Cattle ticks in Cameroon: Is Rhipicephalus (Boophilus) microplus absent in Cameroon and the Central African region?

In most parts of the world, ticks are rapidly developing resistance to commonly used acaricides thus rendering control difficult. This constraint is further compounded by the introduction of new species in areas where they did not exist before. Such is the case with the introduction into and rapid spread of Rhipicephalus (Boophilus) microplus in some countries of West Africa. With the looming threat of its further spread in the region, the objective of the present study was to update knowledge on cattle ticks in Cameroon. Among 19,189 ticks collected monthly from 60 animals in 5 herds from March 2012 to February 2013, Rh. (B.) decoloratus was the most abundant species with a relative prevalence of 62.2%, followed by Amblyomma variegatum (28.4%), Rh. (B.) annulatus (0.2%), Rh. (B.) geigyi (0.03%), other Rhipicephalus spp. (8.4%) and Hyalomma spp. (0.3%). Rh. (B.) decoloratus and A. variegatum were also the most widely distributed in space. Infestation rate was generally high, with average tick count/animal of about 80 during peak periods. Tick distribution and abundance in the different sites was as varied as the underlying factors, among which the most important were management systems and climatic factors. The effects of rainfall and temperature were confounded by other factors and difficult to evaluate. However, it appears tick development depends among other factors, on a humidity threshold, above which there is not much more effect. Rh. microplus was not found during this study, but more extensive tick collections have to be done to confirm this. In conclusion, cattle tick infestation in Cameroon remains an important cause for concern. Farmers need assistance in the use and management of acaricides in order to increase their efficiency and reduce the development of resistance. Although Rh. microplus was not found, its introduction from other West African countries is imminent if adequate measures, especially in the control and limitation of animal movements, are not taken.

Survey of Tick Infestation in Domestic Ruminants of Haramaya District, Eastern Hararghe, Ethiopia

A survey was conducted to determine the prevalence of tick infestation and to identify tick species in domestic ruminants (cattle, sheep and goat) in Adelle, Batte, Tuji-gabisa and Ifa-Oromia kebeles of Haramaya district of Eastern Hararghe, Oromia region. Collection and identification of the ticks were undertaken from November 2013 to March 2014. All visible individual adult ticks were collected from half body part of 265 cattle, and whole body part of 198 sheep and 150 goats. The prevalence of tick infestation in cattle, sheep and goats was found to be 25.23%, 10.1% and 10%, respectively. The most abundant species found in this study were Boophilus decoloratus (47.8%), Amblyomma variegatum (28.4%) and Amblyomma gemma (12.48%), whereas, Rhipicephalus pulchellus (9.3%), Rhipicephalus evertsi evertsi (2.02%). Rhipicephalus evertsi evertsi is the minor species of tick observed on cattle and sheep and none of these ticks were recorded in goats in the study area. Rhipicephalus pulchellus was observed only on cattle and none of these ticks were recorded in sheep and goats. The difference in the prevalence of tick infestation between species and age was statistically significant (X2=25.143, P=0.000 and X2=21.806, P=0.000) respectively. But sex, breed, locality and body condition were not statistically significant (P>0.05). The adult male ticks were more prevalent than the number of adult female ticks except for Boophilus decoloratus the reverse was true. Since they cause severe damage to the hides and skins of domestic ruminants and thereby reduce the foreign exchange of the country; they also transmit tick borne diseases, effective tick control programs should be formulated and implemented in the national or regional level.

Prevalence of Tick Infestation in Different Breeds of Cattle in Maiduguri, Northeastern Nigeria

A survey study was conducted from June to December 2009 using standard parasitological procedures to determine the prevalence of tick infestation among cattle of different breeds in Maiduguri, Northeastern Nigeria. The tick species identified were Boophilus microplus, Amblyomma variegatum, Hyalomma spp., Rhipicephalus sanguineous and Ornithodorus spp. Of the 205 cattle examined, 63.4% (95% CI: 56.8 – 70.0) were tick infested. Males had a non – significantly (P > 0.05) higher infestation rate of 63.4% (56.7 – 71.7) compared with the females 60.9% (46.8 – 75.0). Younger animals aged ? 3 years had a significantly (P < 0.05) higher prevalence of 85.4% (74.6 – 96.2) as compared with the adults aged > 3 – 7 years 55.8% (46.3 – 65.3) and older animals > 7 years 35.0% (22.9 – 47.1). Among breeds, Wadara and Kuri had significantly (P < 0.05) higher infestation rates of 66.1% (57.9 – 74.3) and 66.7% (13.4 – 120.0) respectively. Gudali had 60.9% (41.0 – 80.8), Rahaji 58.0% (44.3 – 71.7) and Bunaji 50.0% (19.3 – 119.3). Based on the predilection sites, the udder and external genitalia, inner thigh and under the tail/perineum were the most tick-infested sites with 84.3% (78.3 – 88.5), 79.0% (73.4 – 84.6) and 69.8% (63.5 – 76.1) respectively (P < 0.05). While the less preferred sites eyes, neck/dewlap, ears and all over the body each had prevalence of 26.3% (20.3 – 32.3), 14.6% (9.8 – 1.4), 12.2% (7.7 – 16.7) and 11.2% (6.9 – 15.5) respectively. This study reveals high prevalence of tick infestation among indigenous cattle in Maiduguri. This might hamper cattle production and productivity in Nigeria. Thus, it is recommended that appropriate control strategies be instituted to control ticks in the study area.DOI: http://dx.doi.org/10.3329/bjvm.v12i2.21279 Bangl. J. Vet. Med. (2014). 12 (2): 161-166

Risk factors associated with clinical dermatophilosis in smallholder sector cattle herds of Zimbabwe at the Amblyomma variegatum and Amblyomma hebraeum interface.

A cross-sectional study was conducted to investigate factors for clinical dermatophilosis herd-level positivity in smallholder dip tanks from Gokwe (Chemawororo, Gwanyika), Kwekwe (Koronika) and Chegutu (Chivero), Zimbabwe, between September 2013 and April 2014. A total of 185 herds were clinically examined for disease and tick infestation. Data on herd and potential herd level risk factors were collected using a structured questionnaire. A herd was classified as clinically positive if an animal satisfied any of the following criteria: small lesions characterised by hairs clumping like a small paint brush, clear exudative circumscribed lesions with scabs of at least 1cm in diameter and confluent progressive exudative scab lesions affecting significant parts of the animal's body. Amblyomma variegatum and Amblyomma hebraeum ticks were identified in situ with further laboratory confirmation. The potential herd-level risk factors for clinical dermatophilosis were tested using multiple logistic regression with herd infection status (positive, negative) being the binomial outcome and risk factors being predictors. Of the herds examined, clinical bovine dermatophilosis was detected in 45% (84/185, 95% confidence interval (CI) 38.2, 52.6%) of the herds. The herd prevalence ranged from 6.9% (95% CI 0.00, 16.7) to 56.7% (95% CI 43.8, 69.6) with Chivero and Chemawororo dip tanks recording the lowest and highest prevalence, respectively. Herds infested with A. variegatum were associated with higher odds (OR = 6.8, 95% CI 1.71, 27.10) of clinical dermatophilosis while the association was not significant (p > 0.05) in A. hebraeum-infested herds. A history of having bought cattle (OR = 3.5, 95% CI 1.09, 11.12) compared to not buying was associated with increased herd clinical positivity status. It was concluded that management practices aimed at movement and tick control would help reduce the prevalence of clinical dermatophilosis in cattle herds.

English

This cross-sectional study was carried out in Raya Azebo district with the objective of determining the prevalence and species diversity of hard ticks encountered in camels. During the study period, a total of 384 camels were examined and 96.6% of them were found infested with ticks. A total of 15,723 ticks were collected from half body regions of infected camels during the study period. The average tick burden from half body region of camels was 42.4 ± 19.63. In this study four genera and ten species of hard ticks were identified. The genera identified were Amblyomma (11.11%), Boophilus (1.8%), Hyalomma (23.32%) and Rhipicephalus (61.77%). The tick species identified during the study period were Amblyomma variegatum, Boophilus decolaratus, Amblyomma cohaerence, Rhipicephalus evertsi evertsi, Rhipicephalus pulchelis, Amblyomma gemma, Amblyomma lepidum, Hyalomma rufipes, Hyalomma dromedarii and Hyalomma truncatum at a prevalence of 22.9, 16.7, 23.2, 41.5, 92.7, 7.8, 3.4, 47.4, 42.7 and 8.9%, respectively. Further study and appropriate control measures are recommended to improve the health and productivity of camel. Key words: Amblyomma, Boophilus, camel, ectoparasite, Hyalomma, Raya Azebo, Rhipicephalus, tick.

Improved molecular detection of Ehrlichia and Anaplasma species applied to Amblyomma ticks collected from cattle and sheep in Ethiopia

Detection of Ehrlichia and Anaplasma species in animals and tick vectors is crucial for an understanding of the epidemiology of diseases caused by these pathogens. In this study, a pair of primers designated EBR2 and EBR3 was designed from the Anaplasma 16S rDNA sequence and was used along with a previously described primer EHR 16SD for the simultaneous detection of Ehrlichia and Anaplasma species by nested PCR. The primers were used to amplify 925bp of DNA from known species of Ehrlichia and Anaplasma. Restriction with MboII and MspI enzymes allowed Ehrlichia and Anaplasma speciation. Restriction with MboII differentiated between An. marginale, Anaplasma (formerly Ehrlichia) sp. Omatjenne, and An. centrale with An. marginale and Anaplasma (formerly Ehrlichia) sp. Omatjenne yielding 2 distinct fragments each while An. centrale produced 3 distinct bands. Ehrlichia ruminantium and An. phagocytophylum remained undigested. Subsequent restriction with MspI differentiated E. ruminantium from An. phagocytophylum with 2 and 4 fragments, respectively. When used on tick samples from the field, 63 ticks (16.4%) out of 384 collected from cattle and sheep were positive for one or more species of Ehrlichia and Anaplasma. The positivity ranged from 6.3% at Andasa to 36.7% at Habernosa. Higher overall infection rates were found in Amblyomma lepidum than in Amblyomma variegatum ticks (p=0.009). Amblyomma lepidum from Habernosa were more often infected with all detected species of Anaplasma and Ehrlichia than Am. variegatum. At Bako, however, Anaplasma (formerly Ehrlichia) sp. Omatjenne was detected only in Am. variegatum. A significantly higher proportion of ticks collected from cattle (20.6%) was found positive than in those collected from sheep (3.3%) (p=0.003). Simultaneous detection of Ehrlichia and Anaplasma species and correct identification of mixed infections was possible. Since the ticks were collected from animals, the occurrence of the major species of Ehrlichia and Anaplasma in ruminants in the area is confirmed.