Acaricidal efficacy evaluation of amitraz and diazinon against Amblyomma variegatum tick species in Waghimra zone, northern Ethiopia.

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.

Prevalence of cattle ixodid ticks and acaricides efficacy evaluation in Amibara district of Afar Region, Ethiopia.

A cross sectional and randomized controlled trial study was conducted starting from July 2021 to July 2022 to determine the prevalence of ixodid ticks, and evaluate the efficacy of commonly used acaricides (amitraz 12.5% and diazinon 60%) in vitro and in vivo on cattle ticks in Amibara district. A total of 372 cattle were visited randomly from six kebeles of the district which were selected based on their livestock population. A total of 4330 adult ticks were collected and identified to the species level with stereomicroscope. For the invitro acaricide efficacy test, 90 engorged female ticks were collected from infested herds and grouped into three, each group having ten engorged ticks; two groups for the two test acaricides and the third groups were control to evaluate these acaricides in the laboratory. All the groups were replicated three times and incubated for seven days with similar temperature and humidity. Thirty-six infested cattle were selected and again grouped into three randomly, 12 each for the invivo test. The first groups of animals were sprayed with amitraz, the second with diazinon and the third groups were left untreated. Ticks were counted and recorded before, day 3, day 7, day 14 and day 21 of spraying. A total of 360 (96.7%) of the visited cattle were infested with ticks. Amblyomma. Rhipicephallus, Hyalomma and Bophillus were the genera of ticks identified with a prevalence of 44.9%, 41.4%, 7.5% and 6.2% respectively. A total of 15 species of ixodid ticks were identified from which Rhipicephallus pulchellus (39.86%) was dominant followed by Amblyomma lepidum (26.65%) and Amblyomma gemma (14.36%). Diazinon 60% EC and amitraz 12.5% were significantly inhibited the egg laying ability of engorged ticks' in vitro with percent inhibition of 100% and 99.1% respectively. On live animal, both acaricides showed statistically significant difference from the control group (p- value <0.05) with maximum 97.37% (amitraz) and 93.33% (diazinon) at day 7 and minimum 73.3% (amitraz) and 73.7% (diazinon) efficacy. However, there was no statistically significant difference on egg laying inhibition and tick count reduction between the two acaricides (p-value >0.05). Therefore, awareness should be created about the high prevalence as well as the application, dosage and dilution of the acaricides to pastoralists, community animal health workers and para veterinarians in the study area. Cattle owners, veterinarians and concerned government officials should address infested herds with manufacturer recommended dosage of these acaricides to control the tick infestation.

Evaluation of Alterations in DNA Methylation of CYP3A4 Gene Upstream Regulatory Elements in Gastric Cancer and in Response to Diazinon Treatment.

BACKGROUND: Little is known about cytochrome P450 3A4 (CYP3A4) DNA methylation and transcription alterations in gastric cancer. OBJECTIVE: In this paper, we initially aimed to address the effect of diazinon pesticide on DNA methylation and transcription changes of the CYP3A4 gene in a human gastric cell line. In the next step, we studied the methylation differences of CpG sites within the upstream regulatory regions of the CYP3A4 gene among human gastric cancerous and healthy tissues. METHODS: For the in vitro assay, the methylation changes of the C/EBP response element and transcript level of the CYP3A4 gene were studied following treatment of the AGS cell line with various concentrations of diazinon pesticide. In the next phase, the methylation percentages of 24 CpG sites within or around the upstream regulatory elements, including near promoter, C/EBP binding site, XREM, and CLEM4, in 11 specimens of human gastric cancer tissue were compared to their adjacent healthy tissues. RESULTS: Treatment with 10 µM Diazinon significantly increased the CYP3A4 gene transcription by approximately 27-fold, which was correlated with the hypermethylation of 3 CpGs in C/EBP binding sites, including -5998, -5731 and -5725 (p<0.001 for all comparisons). Results of bisulfite sequencing revealed that the CpG sites which are located in -1521 (p=0.003), -1569 (p=0.027), -10813 (p=0.003), -10851 (p=0.001) and -10895 (p=0.0) bp from transcription start site, were significantly hypermethylated in cancerous tissues comparing to their healthy cohort. CONCLUSION: Hypermethylation of CLEM4 and a region near the core promoter may have a significant association with gastric cancer incidence.

In Vitro Activity of Beauvericin against All Developmental Stages of Sarcoptes scabiei.

Scabies is a frequent cutaneous infection caused by the mite Sarcoptes scabiei in a large number of mammals, including humans. As the resistance of S. scabiei against several chemical acaricides has been previously documented, the establishment of alternative and effective control molecules is required. In this study, the potential acaricidal activity of beauvericin was assessed against different life stages of S. scabiei var. suis and in comparison with dimpylate and ivermectin, two commercially available molecules used for the treatment of S. scabiei infection in animals and/or humans. The toxicity of beauvericin against cultured human fibroblast skin cells was evaluated using an MTT proliferation assay. In our in vitro model, developmental stages of S. scabiei were placed in petri dishes filled with Columbia agar supplemented with pig serum and different concentrations of the drugs. Cell sensitivity assays demonstrated low toxicity of beauvericin against primary human fibroblast skin cells. At 0.5 and 5 mM, beauvericin showed higher activity against adults and eggs of S. scabiei compared to dimpylate and ivermectin. These results revealed that the use of beauvericin is promising and might be considered for the treatment of S. scabiei infection.

Influence of selective treatment of bulls on the infestation of Haematobia irritans on untreated cows.

The distribution of Hematobia irritans is not homogeneous in cattle populations. Generally, between 15% and 30% of bovines carry more than 50% of the flies, and higher infestations occur in bulls. In this study, the effect of treating the bulls with ear tags containing 40% diazinon on the infestation of flies on the herd during the breeding season was evaluated. Four groups of cattle were made, each containing one bull and 35 Braford cows. Groups 1 and 2 were on pastures in highlands. Groups 3 and 4 were on pastures in lowlands. At the beginning of the trial, each bull from Groups 1 and 3 was treated with an ear tag. Bulls from Groups 2 and 4 remained untreated. Weekly, for 10 weeks, horn flies were counted from each bull and 15 cows from each group. A repeated measures linear mixed model was used with cows as random effects. The number of horn flies in the treated groups was lower than that in the untreated group, suggesting that selective treatment of bulls could be an effective strategy to control horn flies on the herd. The number of flies was higher in the lowland than that in the highland groups, suggesting an effect of the environment on horn fly infestations. In addition, we estimated the cow level predictions from the model to estimate the cow effect on fly counts, and we compared those values with the observed weekly quartiles for each group. Fly-susceptible cows were defined as those for which the infestation of flies appeared in the upper quartile more than 50% of the weeks and in the lower quartile less than 20% of the weeks. In contrast, a fly-resistant cow was defined as one for which the fly counts appeared in the lower quartile more than 50% of the weeks and in the upper quartile less than 20% of the weeks. In all, 8.3% of the cows were susceptible and 15% were resistant. These results may be used to selectively treat bulls or to treat the bulls and the most susceptible cows during the breeding season.

Treatment strategies for sheep scab: An economic model of farmer behaviour.

Ovine psoroptic mange (sheep scab) is a debilitating and damaging condition caused by a hypersensitivity reaction to the faecal material of the parasitic mite Psoroptes ovis. Farmers incur costs from the use of prophylactic acaricides and, if their sheep become infected, they incur the costs of therapeutic treatment plus the economic loss from reduced stock growth, lower reproductive rate, wool loss and hide damage. The unwillingness of farmers to use routine prophylactic treatment has been cited as a primary cause of the growing incidence of sheep scab in the United Kingdom (UK) since the disease was deregulated in 1992. However, if farmers behave rationally from an economic perspective, the optimum strategy that they should adopt will depend on the risk of infection and the relative costs of prophylactic versus therapeutic treatment, plus potential losses. This calculation is also complicated by the fact that the risk of infection is increased if neighbours have scab and reduced if neighbours treat prophylactically. Hence, for any farmer, the risk of infection and optimum approach to treatment is also contingent on the behaviour of neighbours, particularly when common grazing is used. Here, the relative economic costs of different prophylactic treatment strategies are calculated for upland and lowland farmers and a game theory model is used to evaluate the relative costs for a farmer and his/her neighbour under different risk scenarios. The analysis shows that prophylaxis with organophosphate (OP) dipping is a cost effective strategy, but only for upland farmers where the risk of infection is high. In all other circumstances prophylaxis is not cost effective relative to reliance on reactive (therapeutic) treatment. Hence, farmers adopting a reactive treatment policy only, are behaving in an economically rational manner. Prophylaxis and cooperation only become economically rational if the risk of scab infection is considerably higher than the current national average, or the cost of treatment is lower. Should policy makers wish to reduce the national prevalence of scab, economic incentives such as subsidising the cost of acaricides or rigorously applied financial penalties, would be required to make prophylactic treatment economically appealing to individual farmers. However, such options incur their own infrastructure and implementation costs for central government.

Low-level repeated exposure to diazinon and chlorpyrifos decrease anxiety-like behaviour in adult male rats as assessed by marble burying behaviour.

Occupational exposure to organophosphate (OPs) pesticides is reported to increase in the risk of developing anxiety and depression. Preclinical studies using OP levels, which inhibit acetylcholinesterase activity, support the clinical observations, but little is known of the effects of exposure below this threshold. We examined the effects of low level OP exposure on behaviours and neurochemistry associated with affective disorders. Adult rats were administered either diazinon (1 mg/kg i.p.) which is present in sheep dip and flea collars, chlorpyrifos (1 mg/kg i.p.) which is present in crop sprays, or vehicle for 5 days. OP exposure did not affect acetylcholinesterase activity (blood, cerebellum, caudate putamen, hippocampus, prefrontal cortex), anhedonia-like behaviour (sucrose preference), working memory (novel object recognition), locomotor activity or anxiety-like behaviour in the open field arena. In contrast OP exposure attenuated marble burying behaviour, an ethological measure of anxiety. The diazinon-induced reduction in marble burying persisted after exposure cessation. In comparison to vehicle, dopamine levels were lowered by chlorpyrifos, but not diazinon. 5-HT levels and turnover were unaffected by OP exposure. However, 5-HT transporter expression was reduced by diazinon suggesting subtle changes in 5-HT transmission. These data indicate exposure to occupational and domestic OPs, below the threshold to inhibit acetylcholinesterase, can subtly alter behaviour and neurochemistry.

Eficácia do diazinon em uma formulação de uso otológico no tratamento da sarna otodécica em cães / Efficacy of diazinon in an otic solution for the treatment of otodectic mange of dogsGS

O objetivo deste estudo foi avaliar a eficácia de uma solução otológica contendo o inseticida diazinon a 1 por cento no tratamento de infestações por Otodectes cynotis em cães. Foram utilizados 10 cães da raça beagle infestados naturalmente, sendo o ácaro diagnosticado através de otoscopia bilateral. Os animais foram divididos em dois grupos iguais, um controle e o outro tratado. No tratado foi aplicado 1 ml da solução otológica em cada conduto auditivo, durante sete dias consecutivos, correspondendo a 10 mg de diazinon por orelha por dia. Todos os animais foram examinados através de otoscopia nos dias +1, +4, +10, +17 +24 e +31 após o tratamento. Os cães controle apresentavam ácaros em todos os dias de observação. No grupo tratado, o percentual de eficácia do produto foi de 100 por cento em todos os dias de observação, até o dia +31.

Field efficacy of the insect growth regulator dicyclanil for flystrike prevention on lambs.

A multi-centered field trial was carried out in the Netherlands to evaluate the efficacy of a ready-to-use 5% dicyclanil formulation as a preventative of natural flystrike on lambs. In four different sites a total of 1215 lambs treated with dicyclanil were compared with 431 untreated lambs during periods of 15 to 16 weeks. Efficacy was assessed by calculating the weekly cumulative strike rate for each site and treatment group and the percentage reduction achieved by dicyclanil. In two of the four sites untreated controls did not receive enough fly challenge and were not considered for efficacy assessment. At the other two sites untreated controls reached cumulative strike rates of 10.5 and 19.5% 15 and 16 weeks after treatment, respectively. None of the 549 lambs treated with dicyclanil at these two sites were struck, resulting in a 100% reduction of flystrike during the whole length of the trial.

The in vitro response of sheep scab mites to pyrethroid insecticides.

The response of sheep scab mites to pyrethroid insecticides and organophosphate compounds was studied in vitro with the objective of finding a simple test for detecting insecticide resistance in scab mites. Psoroptes cuniculi from rabbits or P. ovis from sheep were enclosed in small 'tea bags' made from heat sealable paper prior to dipping in insecticide. Mites failed to die 24 h after a 1 min dip in working concentrations of insecticidal sheep dips. With flumethrin a variety of different conditions were tested but most failed to improve the efficacy of flumethrin. It is suggested with freshly collected mites pyrethroids may be taken up by ingestion.

Effectiveness of a mixture of cyromazine and diazinon for controlling flystrike on sheep.

OBJECTIVE: To determine whether there is any need for woolgrowers to add diazinon to cyromazine jetting fluid to control active flystrike on sheep. METHOD: Larval implants were placed on 143 sheep and allowed to develop for 2 days. Groups of 47 or 48 of these struck sheep were jetted with cyromazine at 1000 mg/L, diazinon at 400 mg/L, or a mixture of the two. After treatment, the implants were assessed daily for 3 days for the presence of feeding larvae. RESULTS: When checked 1 day after treatment, there was a 62% reduction in flystrike in the diazinon treated sheep compared to only 12% reduction on the cyromazine treated sheep. Flystrike reduction on the sheep jetted with the mixture of cyromazine and diazinon was 69%. Three days after treatment flystrike control was 97 to 99% in the latter two groups. CONCLUSION: Diazinon provided a faster resolution of strikes but by 3 days after treatment there was no significant difference in the number of implants remaining active on the sheep treated with cyromazine or with the mixture of cyromazine and diazinon.

Further evidence that zinc sulphate compromises the efficacy of dipping treatments using diazinon to control sheep lice (Bovicola ovis).

OBJECTIVE: To compare the wettability and efficacy of diazinon dip wash made with and without the addition of zinc sulphate. DESIGN: Field experiments using a shower and a plunge dip complemented by in-vitro wettability experiments. PROCEDURE: A flock of infested sheep was divided into groups and treated in a shower dip with clear or cloudy dam water plus up to 1.5% zinc sulphate. Another infested line of sheep was treated using a plunge dip with nil or 1% zinc sulphate. In both experiments, wetting was assessed after dipping and louse counts were conducted for 9 months after treatment. Five in-vitro experiments compared the wettability of dip wash containing diazinon with up to 1.5% zinc sulphate added. RESULTS: In the shower dipping experiment, live lice were found at 1 month after dipping in the cloudy water groups with 0.75%, 1.0% and 1.5% zinc sulphate and at 2 months in the 0.75% zinc sulphate group. No lice were found at subsequent inspections or at any time in the groups that were plunge dipped. Zinc sulphate decreased the amount of dip wash retained by wool staples in all in-vitro experiments (P < 0.05). CONCLUSION: Zinc sulphate should be considered as a risk factor that could cause failure to eradicate a lice infestation. The risk can be overcome by ensuring that all sheep are saturated at dipping and that the dip wash, and any holding tanks, are agitated throughout the dipping event.

Wound myiasis of sheep in Hungary.

In Hungary, 4388 sheep in six flocks were surveyed in June-August of 1992-1995 to gather basic data on wound myiasis, its incidence, the predominant fly species involved and the clinical manifestations of infestation. The pathogenesis and economic significance of wound myiasis, as well as the interrelation of breed and sex with infestation levels, were evaluated. Active wound myiasis was recorded in all flocks, in 17.6% (774/4388) of the inspected sheep. The incidence varied among flocks and inspections from 4.7% to 38.9%, but it was significantly greater in imported breeds (28.8%, 651/2257) than in indigenous breeds (5.8%, 123/2131). Lesions of wound myiasis were located more frequently on the external genital organs (in 87%, 673/774 of all cases) than on other body regions. Overall, significantly more males (74.3%, 61/82) than females (16.5%, 713/4306) were infested. With the exception of five cases (0.06% of the total), when larvae of Lucilia sericata (Diptera: Calliphoridae) were also found, Wohlfahrtia magnifica (Diptera: Sarcophagidae) was the only species identified in wounds in this study. Despite the fact that larvae of L. sericata were so rarely encountered in wounds, adults of L. sericata were much the more common of the two species observed around wounds, even those infested by W. magnifica. The vast majority of animals inspected had only one myiasis wound. Clinical signs depended on the body part affected. The most severe infestations, in terms of extent of wounds and numbers of visible larvae, were usually those of the vulva and prepuce. Wound consisted of from one up to six foci, each completely filled by larvae of W. magnifica. These foci were either isolated from each other or they merged into a large lesion. Larvae in any focus tended to be at the same stage of development, but, were wounds were very severe, a range of developmental stages was observed together, indicating that frequent restrikes of wounds occurred. The most common signs were restlessness, anxiety and reluctance to graze. The animals were obviously depressed when they suffered from severe infestations causing lameness or blindness. Some of the most severely affected animals displayed obvious loss of condition. However, overall, there was no significant difference between the mean bodyweights of a sample of infested (59.2 kg) and uninfested (60.9 kg) animals.

Studies on the comprehensive control of babesiasis in cattle and buffaloes.

To obtain a highly effective method for controlling babesiosis in cattle and buffalo, an epidemiological survey was carried out at Zuiyun village in Hubai Province. On the grounds of the epidemiological data, control measures which included preventive drugs and killing the vectors were devised. After two years of control no clinical cases of bovine babesiosis were found. The average number of ticks on cattle or buffalo decreased from 9-282 to 0-11.3. Good results were obtained in another epidemic area using this control method. These results indicated that this technique of controlling babesiosis is highly effective.