RESUMEN

Bites of haematophagous ectoparasites cause mechanical injuries and histopathological changes in their hosts' hides and skins whose resultant leathers become unsuitable for certain leather products. The effects of tick bites on the wellbeing of their hosts are known, however, knowledge of their effects on the quality of leathers is scarce. This work investigated the effects of tick bites on the histopathology of skin and the percentage elongation at break (PEB) of shoe upper leathers produced from the skins of Amblyomma variegatum infested Yankasa sheep. A total of nine apparently healthy Yankasa sheep were selectively purchased from the open market and acclimatized for four weeks in the laboratory. Three animals in each of group 1 and 2 were infested with 40 nymphs and 20 adults of Am. variegatum respectively. Group three animals served as uninfested control. All animals were euthanized after the ticks were fully engorged and detached. Skin biopsies at tick attachment points and the uninfested control were taken from flayed skins and processed for histopathological examination. All skins were processed into finished leathers and their PEB determined. Histopathological studies revealed keratinization in all Am. variegatum infested sheep skins, while the un-infested control skins were normal. Mean PEB (%) of leathers were 21.41±3.33SE (nymphs), 36.73±4.44SE (adults) and 47.83±2.78SE (control). Bites of Am. variegatum cause histopathological changes in Yankasa sheep skins that significantly (p = 0.006) reduce the PEB of resultant leathers to less than the acceptable minimum standard of 40 % whose leathers are classified as rejects. In this study, skin of Yankasa sheep infested by nymphs and adults of Am. variegatum ticks resulted in low quality leathers that are unsuitable for standard leather products production and are also of low market value due to keratinization. Sustained efforts need to be undertaken to increase the awareness on the negative impact of tick bites on leather products by encouraging livestock farmers to engage in early treatment of animals infested with ticks.

Asunto(s)

Amblyomma , Enfermedades de las Ovejas , Piel , Infestaciones por Garrapatas , Animales , Ovinos , Enfermedades de las Ovejas/parasitología , Enfermedades de las Ovejas/patología , Infestaciones por Garrapatas/veterinaria , Infestaciones por Garrapatas/parasitología , Piel/parasitología , Piel/patología , Amblyomma/fisiología , Ninfa , Femenino , Mordeduras de Garrapatas/veterinaria , Mordeduras de Garrapatas/parasitología , Masculino

RESUMEN

The growing challenge of acaricide resistance and geographical range expansion of invasive tick species demands other interventions, like plant-based alternatives, for sustainable tick control. Leaves, flowers, seedpods, and twig branch extracts of Senna didymobotrya were analyzed using coupled gas chromatography mass spectrometry (GC-MS). Response of adult Amblyomma variegatum and Rhipicephalus appendiculatus to extracts was evaluated. The most attractive plant extract was fractionated and ticks' responses to its fractions assessed. Potential tick attractants in the attractive plant part extract and its fractions were identified by GC-MS analysis. Non- significant qualitative and quantitative differences were observed in the plant parts' extract composition (R = 0.6178). Flower extracts attracted both species, with a 0.1-fold higher attraction in A. variegatum compared to the standard attraction aggregation attachment pheromone (AAAP). Leaf and seedpod extracts repelled ticks at various concentrations. Bioassays after fractionating flower extracts identified hexane and ethyl acetate fractions as most attractive to A. variegatum (P < 0.001) and R. appendiculatus (P < 0.001), respectively. Chemical analysis of the most attractive extracts and fractions identified compounds, including documented acarine attractants, squalene and linoleic acid. A squalene and linoleic acid blend (1:1) at 1 mg/mL significantly attracted adult A. variegatum (P < 0.01) and R. appendiculatus (P < 0.001). The results of this study broaden comprehension of how ticks respond to plants in nature, and showcase the promising potential for integrating these insights into effective tick management programs.

Asunto(s)

Acaricidas , Amblyomma , Extractos Vegetales , Rhipicephalus , Senna , Animales , Extractos Vegetales/farmacología , Extractos Vegetales/química , Rhipicephalus/efectos de los fármacos , Amblyomma/efectos de los fármacos , Senna/química , Acaricidas/farmacología , Acaricidas/química , Femenino , Flores/química , Cromatografía de Gases y Espectrometría de Masas , Hojas de la Planta/química , Control de Ácaros y Garrapatas/métodos

RESUMEN

Through a collaborative effort across six Sub-Saharan African countries, using recognized international assessment techniques, 23 stocks of three tick species (Rhipicephalus microplus, Rhipicephalus appendiculatus and Amblyomma variegatum) of economic importance for rural small holder farming communities from East and West Africa were collected from cattle, and evaluated in in vitro larval packet tests (LPT). The results demonstrated medium to high resistance to chlorfenvinphos and amitraz across species. Rhipicephalus microplus demonstrated high level alpha-cypermethrin and cypermethrin resistance. Stocks of A. variegatum (West Africa) and R. appendiculatus (Uganda) demonstrated medium level ivermectin resistance. The four least susceptible stocks (East and West African R. microplus, A. variegatum and R. appendiculatus) were taken into in vivo controlled cattle studies where fipronil was found effective against West and East African R. microplus isolates although persistent efficacy failed to reach 90%. Cymiazole and cypermethrin, and ivermectin based acaricides were partially effective against R. microplus without persistent efficacy. Flumethrin spray-on killed A. variegatum within 72 h for up to 10 days posttreatment, however product application was directly to tick attachment sites, which may be impractical under field conditions. A flumethrin pour-on formulation on goats provided persistent efficacy against A. variegatum for up to one-month. Therapeutic control was achieved against R. appendiculatus through weekly spraying cattle with flumethrin, amitraz or combined cymiazole and cypermethrin. A fipronil pour-on product offered four-week residual control against R. appendiculatus (with slow onset of action). Few studies have assessed and directly compared acaricidal activity in vitro and in vivo. There was some discordance between efficacy indicated by LPT and in vivo results. This observation calls for more research into accurate and affordable assessment methods for acaricide resistance. No single active or product was effective against all three tick species, emphasising the need for the development of alternative integrated tick management solutions.

Asunto(s)

Acaricidas , Enfermedades de los Bovinos , Resistencia a Medicamentos , Rhipicephalus , Infestaciones por Garrapatas , Animales , Acaricidas/farmacología , Bovinos , Rhipicephalus/efectos de los fármacos , Infestaciones por Garrapatas/veterinaria , Infestaciones por Garrapatas/tratamiento farmacológico , Infestaciones por Garrapatas/parasitología , Enfermedades de los Bovinos/parasitología , Enfermedades de los Bovinos/tratamiento farmacológico , África Occidental , Ganado/parasitología , Amblyomma/efectos de los fármacos , Larva/efectos de los fármacos , Piretrinas/farmacología , Control de Ácaros y Garrapatas/métodos

RESUMEN

Ticks pose a substantial economic burden associated with production loss and treatment costs globally. Ethiopia has tremendous livestock resources, but its productivity is hindered by various animal health challenges in which ticks are the top priority, with a limited response to acaricidal treatments. Hence, we designed an acaricidal efficacy trial for the top commercially available Chemicals (amitraz and diazinon) to examine their efficacy against the widely distributed tick species (Amblyoma variegatum). Ticks were collected from animals admitted to veterinary clinics with no history of treatment with acaricides. Adult Immersion Technique (AIT) was employed to detect acaricidal resistance, and the mean percent control and antiparasitic efficacy were used to estimate tick susceptibility with a completely randomized laboratory-based trial (CRT). The mean weights of eggs laid by ticks subjected to amitraz and diazinon indicated that amitraz had a better egg-laying-inhibition effect than diazinon. The mean control percentages of amitraz and diazinon were 92.8 ± 5.6% and 69.7 ± 3.1%, respectively, with a highly significant difference (P-value = 0.00). The antiparasitic efficacy of the two drugs was 57.5 ± 0.96 and 37.5% ± 0.96 for amitraz and diazinon, respectively, which revealed that amitraz was statistically better than diazinon in killing adult ticks (P-value =0.026). In general, ticks treated with diazinon showed evidence of resistance development, and amitraz is relatively the most effective acaricide; we recommend its use in the study area and other locations with similar settings.

Asunto(s)

Acaricidas , Rhipicephalus , Animales , Acaricidas/farmacología , Acaricidas/uso terapéutico , Diazinón/farmacología , Diazinón/uso terapéutico , Amblyomma , Etiopía , Antiparasitarios

RESUMEN

BACKGROUND: The majority of the African population lives in rural areas and depends on agriculture for their livelihoods. To increase the productivity and sustainability of their farms, they need access to affordable yield-enhancing inputs of which parasite control is of paramount importance. We therefore determined the status of current tick species with the highest economic impact on cattle by sampling representative numbers of animals in each of seven sub-Saharan countries. METHODS: Data included tick species' half-body counts from approximately 120 cattle at each of two districts per country, collected four times in approximately 1 year (to include seasonality). Study sites were chosen in each country to include high cattle density and tick burden. RESULTS: East Africa (Ethiopia, Uganda and Tanzania) showed overall a higher diversity and prevalence in tick infestations compared to West African countries (Benin, Burkina Faso, Ghana and Nigeria). In East Africa, Amblyomma variegatum (vector of Ehrlichia ruminantium), Rhipicephalus microplus (Babesia bovis, B. bigemina, Anaplasma marginale), R. evertsi evertsi (A. marginale) and R. appendiculatus (Theileria parva) were the most prevalent tick species of economic importance. While the latter species was absent in West Africa, here both A. variegatum and R. microplus occurred in high numbers. Rhipicephalus microplus had spread to Uganda, infesting half of the cattle sampled. Rhipicephalus appendiculatus is known for its invasive behaviour and displacement of other blue tick species, as observed in other East and West African countries. Individual cattle with higher body weights, as well as males, were more likely to be infested. For six tick species, we found reduced infestation levels when hosts were treated with anti-parasiticides. CONCLUSIONS: These baseline data allow the determination of possible changes in presence and prevalence of ticks in each of the countries targeted, which is of importance in the light of human-caused climate and habitat alterations or anthropogenic activities. As many of the ticks in this study are vectors of important pathogens, but also, as cattle may act as end hosts for ticks of importance to human health, our study will help a wide range of stakeholders to provide recommendations for tick infestation surveillance and prevention.

Asunto(s)

Enfermedades de los Bovinos , Rhipicephalus , Infestaciones por Garrapatas , Enfermedades por Picaduras de Garrapatas , Humanos , Masculino , Animales , Bovinos , Ganado , Enfermedades por Picaduras de Garrapatas/epidemiología , Enfermedades por Picaduras de Garrapatas/veterinaria , Enfermedades por Picaduras de Garrapatas/parasitología , Enfermedades de los Bovinos/parasitología , Infestaciones por Garrapatas/epidemiología , Infestaciones por Garrapatas/veterinaria , Infestaciones por Garrapatas/parasitología , Uganda/epidemiología , Burkina Faso

RESUMEN

Since 2011, period of the livestock invasion by the cattle tick Rhipicephalus microplus in Burkina Faso (BF), tick-control problems were exacerbated. Based on farmer's reports, most commonly used commercial acaricides were found to be ineffective in Western South part of the country. To investigate the occurrence and extent of such acaricidal ineffectiveness, we performed the standardized larval packet test (LPT) with commercial deltamethrin (vectocid) and cypermethrin (cypertop), on two cattle tick species, the native Amblyomma variegatum and the invasive R. microplus. The resistance ratios (RR) were computed with susceptible Hounde strain of Rhipicephalus geigyi as reference. The R. microplus population showed resistance to the two acaricides tested with the highest lethal concentration (LC) values, and different resistance ratios higher than 4 (deltamethrin: RR50 = 28.18 and RR90 = 32.41; cypermethrin: RR50 = 8.79 and RR90 = 23.15). In the contrary, A. variegatum population was found to be highly susceptible to acaricides tested with low lethal concentrations and resistance ratio values (deltamethrin: RR50 = 0.5 and RR90 = 0.48; cypermethrin: RR50 = 0.68 and RR90 = 0.79). These data demonstrate high synthetic pyrethroid resistance in R. microplus strain, leading to conclude that the acaricide ineffectiveness in tick populations control remains a concern in BF.

Asunto(s)

Acaricidas , Piretrinas , Rhipicephalus , Amblyomma , Animales , Burkina Faso , Larva , Nitrilos

RESUMEN

Here we present the first detection of a male Amblyomma variegatum tick infesting a sheep on the island of Sardinia, as well as the detection of a pathogen, Rickettsia africae, in DNA extracted from this tick. The tick, the second individual of this species reported in Italy (the first one was reported in Sicily by Albanese in 1971) was collected in August 2018 from the inguinal region of an adult female sheep in a farm located near Sassari (North-West Sardinia). The tick was identified as an adult A. variegatum male under a stereomicroscope using morphological keys. A phylogenetic analysis showed that the 12S sequence clustered with that of African A. variegatum individuals and was embedded within the previously identified West African group. We tested the tick for the presence of microorganisms of the genera Ehrlichia, Rickettsia, Anaplasma, Theileria and Babesia, using published PCR protocols. The tick was found positive to Rickettsia and the obtained sequence matched at 100 % identity with R. africae. The area where the tick was detected was inspected on multiple occasions, looking for other specimens of A. variegatum, without any results. In the same period another male specimen of A. variegatum was found in Haute Corse in 2019. The authors' hypothesis is that the presence of the A. variegatum specimen is an occasional finding, probably linked to the migrating birds that cross Sardinia and Corsica from Africa during summer. Although this may have been an incidental finding, it must be considered that global warming could increase the risk of establishment of colonies of these ticks, that show a strong spreading capability. It is also important to emphasize that this tick species is a proven vector and reservoir of R. africae, an uncommon zoonotic pathogen in Italy, thus additional monitoring must be performed as the establishment of a stable population in Sardinia could represent a serious veterinary and public health issue.

Asunto(s)

Amblyomma/microbiología , Amblyomma/fisiología , Distribución Animal , Rickettsia/aislamiento & purificación , Oveja Doméstica/parasitología , Amblyomma/clasificación , Amblyomma/genética , Animales , Femenino , Italia , Masculino , Filogenia , ARN Ribosómico/análisis

RESUMEN

Ticks are one of the most common vectors of a broad variety of pathogenic agents that significantly affects cattle production causing reduced productivity and important economic losses, while simultaneously having an impact on human health due to the zoonotic risk. In much of the territory of Angola urban population has grown rapidly in recent decades, sharing today close contact with large farms that are generally owned by city residents, providing the ideal conditions for vector-borne pathogens (VBP) transmission between animals and humans. Here we studied the occurrence of Rickettsia, Anaplasma, Ehrlichia, Babesia and Theileria in domestic cattle (n = 98) from Huambo, Angola, and their ticks (n = 116) to obtain a more detailed knowledge into the spectrum of tick-borne agents circulating in this population. We morphologically identified Amblyomma variegatum, Rhipicephalus decoloratus and R. evertsi mimeticus ticks, further confirmed by molecular analysis of the 12S rDNA and 16S rDNA genes. Although none of the bovine blood showed to be positive for R. africae by the ompB, ompA and gltA assays, five ticks showed to be positive for R. africae by the ompB, ompA and the gltA PCRs. Two 18S rRNA sequences were retrieved from bovine blood and one sequence from A. variegatum tick, showing 100% identity with Theileria mutans. By using a PCR targeting the 16S rRNA gene of Anaplama spp. we have also obtained six bovine blood samples showing 99-100 % nucleotide sequence identity with A. capra, two showing 98 % nucleotide sequence identity with A. phagocytophilum and three showing 98-100 % nucleotide sequence identity with A. platys. None of the ticks were positive. The present study shows the presence of a wide range of vector-borne diseases in domestic cattle and their ticks in Huambo province, Angola. Given the lack of both animal and human health infrastructures in this rural region, swift diagnosis and treatment is hampered which could produce a more severe impact on health.

Asunto(s)

Enfermedades de los Bovinos/epidemiología , Ixodidae/fisiología , Infestaciones por Garrapatas/veterinaria , Enfermedades por Picaduras de Garrapatas/epidemiología , Anaplasma/aislamiento & purificación , Anaplasmosis/epidemiología , Anaplasmosis/microbiología , Angola/epidemiología , Animales , Babesia/aislamiento & purificación , Babesiosis/epidemiología , Babesiosis/parasitología , Bovinos , Enfermedades de los Bovinos/microbiología , Enfermedades de los Bovinos/parasitología , Ehrlichia/aislamiento & purificación , Ehrlichiosis/epidemiología , Ehrlichiosis/microbiología , Ehrlichiosis/parasitología , Ehrlichiosis/veterinaria , Ixodidae/microbiología , Ixodidae/parasitología , Prevalencia , Rhipicephalus/fisiología , Rickettsia/aislamiento & purificación , Infecciones por Rickettsia/epidemiología , Infecciones por Rickettsia/microbiología , Infecciones por Rickettsia/veterinaria , Theileria/aislamiento & purificación , Theileriosis/epidemiología , Theileriosis/parasitología , Infestaciones por Garrapatas/epidemiología , Enfermedades por Picaduras de Garrapatas/microbiología , Enfermedades por Picaduras de Garrapatas/parasitología

RESUMEN

Early diagnosis of Ehrlichia ruminantium in cattle is a recipe for effective control of heartwater in ruminants. Hence, we assessed the presence of E. ruminantium in the blood of cattle and the engorged Amblyomma variegatum by nested PCR. The electrophoresed PCR products obtained after primary and secondary amplifications revealed amplicon sizes of about350 bp and 280 bp respectively, which corresponded with the partial region of pSC20 gene amplified. Sequences obtained had 95-99% homology with those sequences available in GenBank. The prevalence of the E. ruminantium in ticks (50%; 126/252) was significantly (p < 0.05) higher than that in cattle blood 23.55% (61/259). The prevalence was significantly (p < 0.05) higher in ticks from adult cattle 51.47% (133/259) than those from the young cattle 44.86% (116/259) and in tick from females 54.55% (141/259) than in ticks from the males 41.38% (107/259). Alignment of autochthonous sequences revealed that the three sequences were polymorphic with two sequences showing similar nucleotides deletion at points 87-91 and 107-108. The phylogenetic trees inferred by ML showed topologies with two autochthonous sequences, one each from cattle blood and tick, clustering together in one clade and the other clustering within those sequences from South Africa and Zimbabwe in another clade. In conclusion, this study revealed a higher prevalence of E. ruminantium in engorged A. variegatum than in the blood of infected cattle. Hence, it is suggested that the amplification that targets the pCS20 gene in engorged ticks may be more suitable to determine the E. ruminantium carrier status of cattle.

RESUMEN

This study was investigated the cause of death of two captive adult Arabian tahrs (Arabitragus jayakari) died within 2-3 days after onset of fever and neurologic signs in a private farm in northern Batinah Region of Oman. Blood counting revealed leukocytosis attributed to neutrophilia and serum chemistry showed hypoproteinemia, increased creatine kinase and BUN. Upon autopsy, the animals exhibited mild ascites and hydrothorax, prominent hydropericardium, with large pale-yellow clear fluid coagulum, prominent epicardial petechiation, as well as severe pulmonary edema associated with frothy fluid in airways. Brain edema with congestion of meningeal and parenchymal vessels was prominent. Histopathology revealed severe congestion and edema of both lung and brain as well as cardiac myopathy. Ehrlichia ruminantium colonies (the causative organism of cowdriosis; OIE-listed disease) were demonstrated in the capillary endothelium of fresh brain squash and lung macrophages. This is the first report of natural E. ruminantium infection in Arabian tahr, the highly endangered species, based on typical clinical signs of acute cowdriosis and demonstration of E. ruminantium colonies in the brain capillary endothelial cells.

Asunto(s)

Ehrlichia ruminantium , Hidropericardio/diagnóstico , Rumiantes , Animales , Animales de Zoológico , Especies en Peligro de Extinción , Hidropericardio/epidemiología , Hidropericardio/patología , Omán/epidemiología

RESUMEN

Here we report the first detection of Amblyomma variegatum, a tick species of medical and veterinary importance, and the first molecular evidence of a pathogen, Rickettsia africae, both new to Corsica (France). In August 2018, an ixodid tick with an unusual morphology was removed from the ventral part of a cow's whole skin in a slaughterhouse located in the village of Ponte-Leccia (Haute-Corse). The tick was morphologically identified as an adult male of A. variegatum. This result was confirmed by 16S rDNA sequence analysis with a close relative being a sequence from Senegal showing 99% nucleotide identity. We tested the tick for Ehrlichia and Rickettsia. The tick was positive to Rickettsia and the corresponding sequence matched with R. africae. There is little or no risk of the introduction and establishment of a viable population of A. variegatum in Corsica by migrating birds. However, if it did, it could produce major economic losses for livestock production. Further studies and sustained surveillance are indicated, not only focusing on this species of tick and this rickettsia, but also on other microorganisms of veterinary and medical importance that might be transmitted in Corsica and other Mediterranean islands.

Asunto(s)

Ixodidae/microbiología , Infecciones por Rickettsia/transmisión , Rickettsia/aislamiento & purificación , Animales , Bovinos , Enfermedades de los Bovinos/parasitología , ADN Bacteriano/análisis , Francia , Masculino , ARN Ribosómico 16S/análisis , Infestaciones por Garrapatas/parasitología , Infestaciones por Garrapatas/veterinaria

RESUMEN

Effective population sizes have rarely been estimated in ticks despite the importance of this parameter for evaluating the evolutionary and adaptive potential of tick populations. The present study was aimed at evaluating the effective population sizes of Amblyomma variegatum, the tropical bont tick, in three villages in Burkina Faso. For this purpose, microsatellites markers were developed. Eight out of 19 assessed markers provided good amplification results with 4 to 24 alleles recorded per marker on 216 genotyped ticks. The within-samples polymorphism was congruent with Hardy-Weinberg expectations at four markers while sex linkage and/or null alleles were observed at the others. As sampling involved two tick generations, effective population sizes were independently estimated by two methods insensitive to heterozygosity: the first one is based on linkage disequilibrium analysis within a single cohort while the second uses the changes in allele frequencies across generations. Both methods estimated the number of reproducing ticks ranging from two to a few tens reproductive adults per village and cohort. Such small estimates are congruent with the rarity of records of acaricide resistance in A. variegatum.

Asunto(s)

Ixodidae/fisiología , Polimorfismo Genético , Animales , Burkina Faso , Femenino , Ixodidae/genética , Masculino , Repeticiones de Microsatélite , Densidad de Población

RESUMEN

The leaf latex of Aloe yavellana Reynolds is traditionally used for the treatment of various illnesses of humans and domestic animals in Ethiopia. In the present study, the latex and two major compounds isolated from it, namely, aloin A/B and microdontin A/B were assessed for their larvicidal activity against Amblyomma variegatum tick larvae using a larval packet test (LPT). The LC50 and LC99 of the latex were found to be 35.82 ± 2.27 and 83.48 ± 3.95 mg/ml, respectively. Although microdontin A/B showed better larvicidal activity (LC50 = 89.40 ± 4.45 mg/ml) than aloin A/B (LC50 = 257.69 ± 6.31 mg/ml), neither of the isolated compounds was as active as the latex suggesting that the compounds acted synergistically or minor compounds with potent larvicidal activity may exist in the latex. The results confirmed that the leaf latex of A. yavellana and its isolated compounds could have the potential to be used as larvicidal against A. variegatum ticks.

Asunto(s)

Acaricidas/administración & dosificación , Aloe/química , Ixodidae/efectos de los fármacos , Larva/efectos de los fármacos , Látex/administración & dosificación , Hojas de la Planta/química , Acaricidas/química , Acaricidas/aislamiento & purificación , Animales , Bovinos/parasitología , Enfermedades de los Bovinos/parasitología , Emodina/análogos & derivados , Emodina/farmacología , Humanos , Ixodidae/fisiología , Látex/química , Látex/aislamiento & purificación

RESUMEN

Tick acaricide failure is one of the leading challenges to cattle production in Uganda. To gain an understanding into the possible drivers of acaricide failure, this study characterized the current chemical tick control practices in the southwestern (Mbarara, Mitooma and Rukungiri districts) and northwestern (Adjumani district) regions of Uganda. A total of 85 farms participated in a survey that utilized a semi-structured questionnaire. Moreover, ticks were collected to determine the most common species on the farms. Tick acaricide failure was mainly encountered in the districts where 95% (60/63) of the farms reared exotic cattle (dairy cross-breeds) under a paddocking (fenced) system. In the northwestern region, local cattle were reared in communal grazing areas. All farms used chemical acaricides for tick control, predominantly amidine (amitraz) (48%, 41/85) and co-formulated organophosphates and pyrethroids (38%, 32/85). The spraying method was the most common (91%, 77/85) acaricide application technique, with cattle crush (81%, 69/85) as a common means of physical restraint. Less than optimal tick control practices encountered included use of substandard equipment for spraying, inappropriate dilutions, frequent interaction between animals in neighboring farms despite lack of synchronized chemical tick control and malpractices in acaricide rotation. Only Rhipicephalus appendiculatus and R. (Boophilus) decoloratus ticks were found in the southwestern region, where 51% (32/63) of the farmers used high acaricide concentrations above the manufacturers' recommendation. Farmers in the northwestern region used 2.2 times less acaricide volume per cattle than those in the southwestern region, and more diverse tick species were encountered. Toxic effects of acaricide to cattle and workers were reported by 13% (11/85) and 32% (27/85) of the respondents, respectively. All 27 cases of human acaricide toxicity reported were from the southwestern region. Overall, our findings may inform strategies for more prudent chemical tick control and safe acaricide handling to benefit animal welfare, food safety and public health.

Asunto(s)

Acaricidas/efectos adversos , Enfermedades de los Bovinos/tratamiento farmacológico , Control de Ácaros y Garrapatas/métodos , Infestaciones por Garrapatas/veterinaria , Garrapatas/efectos de los fármacos , Acaricidas/administración & dosificación , Acaricidas/toxicidad , Animales , Bovinos , Enfermedades de los Bovinos/epidemiología , Enfermedades de los Bovinos/parasitología , Estudios Transversales , Resistencia a Medicamentos , Granjas , Humanos , Salud Pública , Piretrinas/administración & dosificación , Piretrinas/efectos adversos , Rhipicephalus/efectos de los fármacos , Encuestas y Cuestionarios , Control de Ácaros y Garrapatas/estadística & datos numéricos , Infestaciones por Garrapatas/tratamiento farmacológico , Infestaciones por Garrapatas/epidemiología , Enfermedades por Picaduras de Garrapatas/prevención & control , Enfermedades por Picaduras de Garrapatas/veterinaria , Toluidinas/administración & dosificación , Toluidinas/efectos adversos , Uganda/epidemiología

RESUMEN

In many African countries including Benin, the reluctance of some livestock owners to blood collection from their cattle makes epidemiological surveys cumbersome and prevents regular monitoring of tick-borne diseases. In the present study, Amblyomma variegatum ticks were used to find out more about bovine tick-borne pathogens. DNA extracts from 910 adult ticks collected off cattle in North East Benin were examined for Babesia bigemina, B. bovis, Theileria taurotragi, T. annulata, T. orientalis, T. parva, T. mutans, Anaplasma marginale and Ehrlichia ruminantium using pathogen-specific PCR assays and sequence analyses. Altogether, 21.6% of the ticks carried at least one pathogen. A. marginale (142/910) was the most frequent pathogen, followed by E. ruminantium (57/910), B. bovis (10/910), T. mutans (3/910) and B. bigemina (1/910). Theileria taurotragi, T. annulata, T. orientalis, T. parva were not detected in the samples. Babesia bigemina, B. bovis and T. mutans were present in only one location whereas A. marginale and E. ruminantium were found in ticks from 7/8 locations surveyed. Coinfections occurred in 7.1% of all positive ticks. The analyses of partial sequences of B. bovis spherical body protein 4, B. bigemina rhoptry-associated protein-1a, T. mutans 18S rRNA and A. marginale major surface protein 5 showed high sequence conservation and homologies between Benin isolates and those from other African countries. However, E. ruminantium pCS20 partial sequences were different from published West African isolates and presented similar genetic variation with South and East African isolates. These results provide information on the pathogens circulating in North East Benin and suggest that Am. variegatum, one of the most abundant ticks in Africa, may play a role in the transmission of A. marginale.

Asunto(s)

Anaplasmataceae/genética , Piroplasmida/genética , Enfermedades por Picaduras de Garrapatas/veterinaria , Garrapatas/microbiología , Garrapatas/parasitología , Anaplasmataceae/aislamiento & purificación , Infecciones por Anaplasmataceae , Animales , Babesiosis/epidemiología , Benin/epidemiología , Bovinos , Enfermedades de los Bovinos/prevención & control , ADN Protozoario/genética , Ehrlichia ruminantium/aislamiento & purificación , Femenino , Hidropericardio/epidemiología , Masculino , Piroplasmida/aislamiento & purificación , Reacción en Cadena de la Polimerasa , Theileriosis/epidemiología , Enfermedades por Picaduras de Garrapatas/epidemiología , Enfermedades por Picaduras de Garrapatas/parasitología

RESUMEN

The tropical bont tick, Amblyomma variegatum, is a tick species of veterinary importance and is considered as one of major pest of ruminants in Africa and in the Caribbean. It causes direct skin lesions, transmits heartwater, and reactivates bovine dermatophilosis. Tick saliva is reported to affect overall host responses through immunomodulatory and anti-inflammatory molecules, among other bioactive molecules. The general objective of this study was to better understand the role of saliva in interaction between the Amblyomma tick and the host using cellular biology approaches and proteomics, and to discuss its impact on disease transmission and/or activation. We first focused on the immuno-modulating effects of semi-fed A. variegatum female saliva on bovine peripheral blood mononuclear cells (PBMC) and monocyte-derived macrophages in vitro. We analyzed its immuno-suppressive properties by measuring the effect of saliva on PBMC proliferation, and observed a significant decrease in ConA-stimulated PBMC lymphoproliferation. We then studied the effect of saliva on bovine macrophages using flow cytometry to analyze the expression of MHC-II and co-stimulation molecules (CD40, CD80, and CD86) and by measuring the production of nitric oxide (NO) and pro- or anti-inflammatory cytokines. We observed a significant decrease in the expression of MHC-II, CD40, and CD80 molecules, associated with decreased levels of IL-12-p40 and TNF-α and increased level of IL-10, which could explain the saliva-induced modulation of NO. To elucidate these immunomodulatory effects, crude saliva proteins were analyzed using proteomics with an Orbitrap Elite mass spectrometer. Among the 336 proteins identified in A. variegatum saliva, we evidenced bioactive molecules exhibiting anti-inflammatory, immuno-modulatory, and anti-oxidant properties (e.g., serpins, phospholipases A2, heme lipoprotein). We also characterized an intriguing ubiquitination complex that could be involved in saliva-induced immune modulation of the host. We propose a model for the interaction between A. variegatum saliva and host immune cells that could have an effect during tick feeding by favoring pathogen dissemination or activation by reducing the efficiency of host immune response to the corresponding tick-borne diseases.

Asunto(s)

Factores Inmunológicos/metabolismo , Ixodidae , Leucocitos Mononucleares/efectos de los fármacos , Macrófagos/efectos de los fármacos , Saliva/metabolismo , Proteínas y Péptidos Salivales/metabolismo , Animales , Antígenos CD/análisis , Bovinos , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Citocinas/análisis , Antígenos de Histocompatibilidad Clase II/análisis , Leucocitos Mononucleares/inmunología , Macrófagos/inmunología , Óxido Nítrico/análisis

RESUMEN

Ixodid ticks are well known for spreading transmitted tick-borne pathogens while being attached to their hosts for almost 1-2 weeks to obtain blood meals. Thus, they must secrete many immunosuppressant factors to combat the hosts' immune system. In the present work, we investigated an immunosuppressant peptide of the hard tick Amblyomma variegatum. This peptide, named amregulin, is composed of 40 residues with an amino acid sequence of HLHMHGNGATQVFKPRLVLKCPNAAQLIQPGKLQRQLLLQ. A cDNA of the precursor peptide was obtained from the National Center for Biotechnology Information (NCBI, Bethesda, MD, USA). In rat splenocytes, amregulin exerts significant anti-inflammatory effects by inhibiting the secretion of inflammatory factors in vitro, such as tumor necrosis factor-alpha (TNF-α), interleukin-1 (IL-1), interleukin-8 (IL-8) and interferon-gamma (IFN-γ). In rat splenocytes, treated with amregulin, compared to lipopolysaccharide (LPS) alone, the inhibition of the above inflammatory factors was significant at all tested concentrations (2, 4 and 8 µg/mL). Amregulin shows strong free radical scavenging and antioxidant activities (5, 10 and 20 µg/mL) in vitro. Amregulin also significantly inhibits adjuvant-induced paw inflammation in mouse models in vivo. This peptide may facilitate the ticks' successful blood feeding and may lead to host immunotolerance of the tick. These findings have important implications for the understanding of tick-host interactions and the co-evolution between ticks and the viruses that they bear.

Asunto(s)

Antiinflamatorios/farmacología , Antioxidantes/farmacología , Inmunosupresores/farmacología , Péptidos/farmacología , Animales , Citocinas/metabolismo , Edema/tratamiento farmacológico , Ixodidae , Lipopolisacáridos/farmacología , Masculino , Ratones , Ratas Wistar , Glándulas Salivales/química , Bazo/citología , Bazo/metabolismo

RESUMEN

Spotted fever group (SFG) rickettsiae are obligate intracellular, Gram-negative bacteria transmitted by ticks and causing febrile illness in humans. Despite the presence of suitable tick vectors, the occurrence of SFG rickettsiae has never been investigated in the Republic of Benin (West Africa). In the present study, 910 Amblyomma variegatum ticks collected from 8 different locations in North Eastern Benin were tested for SFG rickettsiae. The samples were first screened for the presence of rickettsial bacteria using 16S rDNA PCR and positive samples were subsequently characterized by ompA PCR. Randomly selected samples among those positive for both assays were subjected to sequencing of 16S rDNA and ompA genes for species identification. The 16S rDNA gene was amplified in 63.4% of the samples (585/910) and the SFG rickettsia-specific ompA gene was detected in 29.4% of the samples (267/910). The prevalence of SFG rickettsiae varied according to the location, and tick gender. Sequence analyses demonstrated the presence of Rickettsia africae and/or closely related species in Benin. These findings extend the geographic distribution of R. africae and spotted fever rickettsioses in Africa. Clinicians in Benin and those treating travellers should be aware of the possibility of SFG rickettsiae infection when they are treating patients with febrile illness.

Asunto(s)

Vectores Arácnidos/microbiología , Ixodidae/microbiología , Infecciones por Rickettsia/epidemiología , Rickettsia/aislamiento & purificación , Animales , Proteínas de la Membrana Bacteriana Externa/genética , Benin/epidemiología , ADN Bacteriano/genética , Femenino , Humanos , Masculino , Filogenia , Reacción en Cadena de la Polimerasa , Rickettsia/clasificación , Rickettsia/genética , Infecciones por Rickettsia/microbiología , Infecciones por Rickettsia/transmisión , Análisis de Secuencia de ADN , Viaje

RESUMEN

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.

Asunto(s)

Anticuerpos Antibacterianos/sangre , Ixodidae/microbiología , Complicaciones Infecciosas del Embarazo/microbiología , Infecciones por Rickettsia/microbiología , Rickettsia/aislamiento & purificación , Adulto , Animales , Femenino , Humanos , Madagascar/epidemiología , Filogenia , Embarazo , Complicaciones Infecciosas del Embarazo/sangre , Complicaciones Infecciosas del Embarazo/epidemiología , Rickettsia/genética , Infecciones por Rickettsia/epidemiología

RESUMEN

The in vitro toxicity of Millettia ferruginea darasana (family: Fabaceae) was tested against the larvae adult male and female of a three-host tick, Amblyomma variegatum Fabricius (family: Ixodidae or hard tick), known as 'tropical bont tick' parasitic mainly to cattle found in Ethiopia and other equatorial Africa. The 20, 40, 60, 80 and 100 % concentrations of the seed oil extracted with petroleum ether were found to kill all (100 % mortality) larvae after 12, 9, 6, 3 and 1.5 h respectively. The results summarized in the Table 1 was found to be statistically significant at the probability level of p = 0.05. The 100 % concentration of the oil caused 100 % mortality of adult male, adult female and fully engorged female tick after 5, 7 and 12 h respectively. The root and root bark showed less toxicity. The leaves did not show any toxicity. [Table: see text].