Epidemiological aspects of bovine parasitic otitis caused by Rhabditis spp. and/or Raillietia spp. in the state of Minas Gerais, Brazil

Synthesis and anthelmintic activity of novel thiosemicarbazide and 1,2,4-triazole derivatives: In vitro, in vivo, and in silico study

INTRODUCTION

Intestinal parasitic infections are neglected diseases and, due to the increasing resistance of parasites to available drugs, they pose an increasing therapeutic challenge. Therefore, there is a great need for finding new compounds with antiparasitic activity.

OBJECTIVES

In this work, new thiosemicarbazide and 1,2,4-triazole derivatives were synthesized and tested for their anthelmintic activity.

METHODS

The synthesis was carried out by classical methods of organic chemistry. Anthelmintic activity tests were carried out in vitro (Rhabditis sp., Haemonchus contortus, Strongylidae sp.) in vivo (Heligmosomoides polygyrus/bakeri), and in silico analysis was performed.

RESULTS

Quinoline-6-carboxylic acid derivative compounds were designed and synthesized. The highest activity in the screening tests in the Rhabditis model was demonstrated by compound II-1 with a methoxyphenyl substituent LC50 = 0.3 mg/mL. In the next stage of the research, compound II-1 was analyzed in the H. contortus model. The results showed that compound II-1 was active and had ovicidal (percentage of dead eggs > 45 %) and larvicidal (percentage of dead larvae > 75 %) properties. Studies in the Strongylidae sp. model confirmed the ovicidal activity of compound II-1 (percentage of dead eggs ≥ 55 %). In vivo studies conducted in the H. polygyrus/bakeri nematode model showed that the number of nematodes decreased by an average of 30 % under the influence of compound II-1. In silico studies have shown two possible modes of action of compound II-1, i.e. inhibition of tubulin polymerization and SDH. The test compound did not show any systemic toxic effects. Its influence on drug metabolism related to the activity of cytochrome CYP450 enzymes was also investigated.

CONCLUSION

The results obtained in the in vitro, in vivo, and in silico studies indicate that the test compound can be described as a HIT, which in the future may be used in the treatment of parasitic diseases in humans and animals.

Anthelminthic and antimicrobial effects of hedge woundwort (Stachys sylvatica L.) growing in Southern Kazakhstan

The Stachys L. genus has been widely used in traditional medicine in many countries throughout the world. The study aimed to investigate the chemical composition and bioactivity of the hydroethanolic extract (50% v/v) obtained by ultrasonication from the aerial flowering parts of Stachys sylvatica L. (SSE) collected in Almaty region (Southern Kazakhstan). According to RP-HPLC/PDA analysis the leading metabolites of the SSE belonged to polyphenols: chlorogenic acid and its isomers (2.34 mg/g dry extract) and luteolin derivatives (1.49 mg/g dry extract), while HPLC-ESI-QTOF-MS/MS-based qualitative fingerprinting revealed the presence of 17 metabolites, mainly chlorogenic acid and its isomers, flavonoid glycosides, and verbascoside with its derivatives. GC-MS analysis of the volatile metabolites showed mainly the presence of diterpenoids and fatty acid esters. A reduction in the viability of nematodes Rhabditis sp. was obtained for the SSE concentration of 3.3 mg/mL, while 11.1 mg/mL showed activity comparable to albendazole. The SSE exhibited higher activity against Gram-positive (MIC = 0.5-2 mg/mL) than Gram-negative bacteria and yeast (MIC = 8 mg/mL), exerting bactericidal and fungicidal effects but with no sporicidal activity. The SSE showed some antiviral activity against HCoV-229E replicating in MRC-5 and good protection against the cytopathic effect induced by HHV-1 in VERO. The SSE was moderately cytotoxic towards human cervical adenocarcinoma (H1HeLa) cells (CC50 of 0.127 mg/mL after 72 h). This study provides novel information on the SSE extract composition and its biological activity, especially in the context of the SSE as a promising candidate for further antiparasitic studies.

The first human case of rhabditiasis in Bangladesh

Rhabditiasis, caused by Rhabditis nematode, has long been recognized as a veterinary concern, however, human infection is exceedingly rare. For the first time in Bangladesh, this study confirmed human rhabditiasis infecting a 12-year-old child. The identification was made based on morphometric features and confirmed by amplifying the mitochondrial cox1 gene. During microscopical examination of stool samples, heavy infection with several developmental stages (larvae, adult males, and females) of nematodes was observed. Following morphometric analysis, the nematode was identified as Rhabditis sp. The features used in confirming the species were elongated tail, bulbous enlargement of mid-esophagus, and presence of adult males passed in the stool. The results of the phylogenetic analysis showed that isolates of Rhabditis sp. belonged to distinct clades alongside S. stercoralis.

Raillietia auris (Mesostigmata: Raillietiidae) in cattle in the state of Mato Grosso do Sul, Brazil

Parasitic otitis in cattle, caused by mites, has been reported from several continents. The present study aimed to determine the distribution, prevalence, intensity, mean intensity, and range of the agent in cattle in the state of Mato Grosso do Sul, Brazil. The samples were designed at random, with an acceptable margin of error of 3% and a confidence interval of 99%. A total of 449 animals were sampled immediately after slaughter from 34 different municipalities in the state using the technique of flushing both ear canals. Only Raillietia auris (Leidy, 1872) were found, with a prevalence of 98.6%, mean intensity of 53.78 mites/animal, and a range of 1-323. Impressively, the prevalence found was identical to another survey carried out 39 years ago in the same region. Details about the parasite intensity in different age categories of the animals are presented. The study demonstrates that the prevalence and intensity of infestation by Raillietia auris are high, and in older cattle are higher than young ones.

Rhabditis spp., in the Espírito Santo, State of Brazil and evaluation of biological control

The objectives of this study were to describe occurrences of Rhabditis spp. causing parasitic otitis in dairy cattle of Gir breed in the state of Espírito Santo, southeastern Brazil, and to evaluate the biological control of this nematode using the nematophagous fungi Duddingtonia flagrans (AC001) and Monacrosporium thaumasium (NF34). After nematode detection and collection, three groups were formed: two groups that were treated, respectively, with the fungal isolates; and a control group, without fungus. The treatments were as follows: (a) Petri dishes containing the culture medium 2% water agar (WA) + 250 nematodes + AC001; (b) Petri dishes containing 2% WA + 250 nematodes + NF34; and (c) Petri dishes containing only 2% WA + 250 nematodes. After seven days at 27 °C the treatments with fungi were able to capture and destroy the nematodes, with percentages of 82.0% (AC001) and 39.0% (NF34) in relation to the control group. The results demonstrate the occurrence of Rhabditis spp. after animals physical examination and that there was efficacy of the in vitro predatory activity of both fungal isolates. Thus, these results are important because they can assist in future in vivo control of this nematode in cattle.

Brainstem and Cranial Nerve Disorders of Ruminants

Asymmetrical signs of brainstem disease occur relatively infrequently in ruminants. The most common differential diagnoses include listeriosis, otitis media/interna, and pituitary abscess syndrome. Although these conditions produce signs of brainstem dysfunction, the diseases can usually be differentiated based on historical findings and subtle clinical differences. Basic laboratory diagnostic tests are often not specific in the definitive diagnosis but may be supportive. Advanced imaging techniques have proven to be useful in the diagnosis of otitis media/interna. Presumptive clinical diagnosis is confirmed at necropsy. Treatment involves a prolonged course of antibiotic therapy but is unrewarding in cases of pituitary abscess syndrome.

Detecção e tratamento de otite por Rhabditis blumi em bovinos da região Norte do Brasil

Resumo: O presente estudo teve como objetivo descrever a ocorrência de otite parasitária causada por Rhabditis blumi em bovinos leiteiros de raça Gir de uma fazenda da região Norte do Brasil. Foram coletadas amostras de 42 bovinos por swab e lavado dos condutos auditivos externos (CAE). Ao exame clínico, 9,5% (4/42) dos bovinos apresentavam sintomatologia nervosa, como leve a moderada rotação da cabeça, apatia, flacidez dos lábios e ptose palpebral unilateral, alopecia das regiões da cabeça e cupim, causados pelo desconforto e prurido da região auricular, alteração na mastigação e acúmulo de alimento na cavidade oral. Adicionalmente, 71,4% (30/42) dos abovinos mostraram a presença do parasita no cerúmen dos condutos auditivos. À análise microscópica do material do saco conjuntival foi observado presença do parasita em 90% (9/10) dos bovinos avaliados. Os 30 bovinos positivos para Rhabditis spp. foram distribuídos aleatoriamente em três grupos de 10 animais: (G1) Bovinos controle, (G2) Bovinos tratados com ivermectina 1% pour on e (G3) Bovinos submetidos a lavado dos condutos auditivos externos (CAE). Cada tratamento foi repetido três vezes com intervalo de sete dias. No G1 os 10 bovinos mantiveram-se infectados durante todo o estudo. No G2 20% dos bovinos foram negativos após os dois primeiros tratamentos, porém, mostraram-se positivos na terceira avaliação. No G3 todos os bovinos mantiveram-se positivos, sendo observada apenas diminuição da carga parasitária. A identificação por análise molecular por meio de fragmentos amplificados da expansão D2/D3 do 28S rDNA confirmou a presença apenas da espécie Rhabditis blumi nos animais. Baseado nas observações clínicas, morfológicas e moleculares pode-se relatar o primeiro caso de R. blumi em bovinos da raça Gir no Estado do Pará, através da compra de animais oriundos de áreas onde a otite parasitária tem sido diagnosticada, principalmente de Minas Gerais, para formar animais mestiços (Gir x Holandês). Desta forma ressalta-se a importância do exame clínico prévio dos animais a serem transferidos para outras propriedades ou regiões. Este relato também parece ser o primeiro sobre a presença de R. blumi no saco conjuntival de bovinos. O tratamento com ivermectina no G2 não surtiu melhora clínica dos bovinos.

Outer ear canal infection with Rhabditis sp. nematodes in a human

Here we report the first human case of an outer ear canal infection with a free-living nematode of the genus Rhabditis. Otomicroscopy revealed viable worms in the outer ear canal of a patient suffering from chronic otorrhea and hearing loss. The nematode was identified by microscopy and internal transcribed spacer (ITS)-PCR.

Clinical aspects and dynamics of auricular parasitosis in Gir cattle

We evaluated the dynamics of ear infestations caused by Rhabditis spp. and Raillietia spp., which were correlated with animal age, intensity of clinical signs and climate factors. Sixty-four Gir cattle were distributed into three groups: GA - 23 calves with 4 to 6 months of age; GB - 18 calves with 7 to 12 months of age; and GC - 23 heifers with 13 to 33 months of age. Five samplings, defined as S1, S2, S3, S4 and S5 were performed every three months from August 2008 to August 2009. The ear secretion was collected using the auricular washing method for the right ear and a swab for the left ear. A clinical assessment of the animals was performed, and they were classified according to the presence and severity of otitis. The highest relative frequency of rhabditosis was 52.2% in GC at the last sampling. In the first sampling, 42.2% of the animals were infested by Raillietia spp. The older cattle were more susceptible to infestations by both parasites. No correlation of Rhabditis spp. and Raillietia spp. parasitism with climate factors was found. The results showed that both parasites could infest Gir cattle, and in most cases, there was no co-infestation. Only older animals parasitized by the nematode showed clinical signs of the disease.

The role of ear mites of the genus Raillietia (Acari: Raillietiidae) in otitis of domestic ruminants

This paper presents a hypothesis on the involvement of species of the genus Raillietia Trouessart in the pathology of parasitic otitis in domestic ruminants. The chelicerae and claws of the tarsi are structures that contribute significantly towards producing primary lesions. The movable digits of the chelicerae accidentally injure the epithelium that lines the ear canal, while the claws of the tarsi perforate the epithelium, allowing the mites to affix themselves while feeding. The lesions in the epithelium caused by the chelicerae and the claws favor multiplication of the bacteria that inhabit the ear canal, resulting in typical cases of otitis.

Inefficacy of albendazole sulphoxide and ivermectin for the treatment of bovine parasitic otitis caused by rhabditiform nematodes

The purpose of this study was to evaluate the efficacy of orally administered albendazole sulphoxide and pour-on ivermectin for the treatment of bovine parasitic otitis caused by rhabditiform nematodes. Eighteen Gyr cows presenting clinical otitis were divided in three groups with six animals each. The first one did not receive any treatment (control group). The second one was treated with 0.5% pour-on ivermectin, 500µg/kg of body weight, and the third group was treated with oral 6% albendazole sulphoxide, at 6.0mg/kg. Both ear canals of each animal were reexamined on days 7 and 21 post treatment. The animals in the control group remained infected throughout the days of observation. Ivermectin treatment did not show effectiveness on days 7 or 21 post treatment. The albendazole sulphoxide treatment had an efficacy of 16.7 and 25% on days 7 and 21, respectively. Further studies are required to assess an effective treatment for this parasitic disease, especially via alternative administration routes, because of its significant impact on Bos taurus indicus cattle breeding in Tropical and Subtropical Regions.

Molecular characterization of Malassezia sympodialis and Malassezia furfur from cattle with and without otitis

A molecular study of Malassezia strains isolated from cattle with or without otitis was carried out by random amplified polymorphic DNA analysis (RAPD). DNA was extracted and purified from nine strains of Malassezia sympodialis and fourteen of Malassezia furfur. These microorganisms were collected from eight different bovine herds in Minas Gerais state, Brazil. The RAPD analysis and phenograms did not show the formation of genetically distinct groups among the strain isolated from cattle with or without otitis raised in the same herds. Genetic heterogeneity was observed among Malassezia strains from different geographic origins. These data suggest that genetically similar M. sympodialis and M. furfur strains found as members of the normal ear microbiota could become opportunistically active in the inflammatory process in cattle.

Susceptibility of yeast isolates from cattle with otitis to aqueous solution of povidone iodine and to alcohol-ether solution

Lipid-dependent Malassezia species, Candida spp. and Rhodotorula mucilaginosa have been associated with bovine parasitic otitis. This paper evaluated the susceptibility of 63 yeast isolates from cattle with otitis to a povidone iodine aqueous solution (1% and 0.5% v/v) and to an alcohol-ether solution (1:1 v/v). The effectiveness of these antiseptics was assessed using the European suspension test. Products achieving equal to or greater than 5-log reduction in numbers of the challenge organism after 5 min contact are considered to have as acceptable microbicidal effect (ME). The two antiseptic solutions achieved ME greater than 5, when tested at 1 and 5 min contact time, against the majority of yeast strains. The exceptions were alcohol and ether solution against two Candida tropicalis strains. Urea broth macrodilution method was used to determine the minimum inhibitory concentration (MIC), defined as the lowest concentration that resulted in a visually negative urease test or, in the case of Candida spp., turbidity inhibition when compared with that produced by the growth control. Analysis of the results for all 63 isolates showed Malassezia sympodialis and Rhodotorula mucilaginosa to be more susceptible to povidone iodine and Malassezia furfur strains to be less susceptible. Malassezia sympodialis was significantly more susceptible to alcohol-ether solution than other species. This study showed the in vitro efficacy of alcohol-ether solution and povidone iodine and proposes the need for clinical evaluation of the topical treatment and control of bovine otitis with these antiseptics and their effects on the ear microbiota and the ear canal.

Occurrence of the ear-mite Raillietia auris in cattle in Austria

We describe here the first documented case in Austria of the cattle ear mite Raillietia auris in a four-year-old dairy cow. The cow was mildly depressed, and keratoconjunctivitis was diagnosed in both eyes with Horner's syndrome in the left eye. The animal showed a mild head tilt to the left and a generalized ataxia with a tendency to move to the right side, which became exacerbated if the animal was blind-folded. Head pressing to the right side, dysphagia and a dropped jaw were also observed. Numerous rather mobile ear mites were observed at necropsy in the basal part of the left ear canal. The clinical significance of the cattle ear mite is uncertain and the clinical signs could have been caused by listerial encephalitis, which was also confirmed histologically in this case.

Otitis in cattle, an aetiological review

Otitis externa in cattle has a significant impact in tropical and subtropical regions, and the aetiological agents are predominantly rhabditiform nematodes and mites of the genus Raillietia. Its prevalence is higher in mature and Zebu cattle. In advanced clinical cases there can be irreversible and fatal neural lesions. Ear infection in calves has been associated with concurrent respiratory diseases and mixed infection. The principal reported agents of otitis in calves are bacteria such as Actinomyces spp., Corynebacterium pseudotuberculosis, Escherichia coli, Haemophilus somnus, Pasteurella multocida, Mannheimia haemolytica, Pseudomonas spp., Streptococcus spp. and Mycoplasma bovis. The control and treatment of bovine otitis is not standardized and there is little evidence-based support for the diverse treatments available in the literature.

Factors associated with the prevalence of Malassezia species in the external ears of cattle from the state of Minas Gerais, Brazil

Swabs collected from the external ears of 942 cattle, including both European and zebu breeds, were used to evaluate the epidemiology of Malassezia species. High numbers of Malassezia isolates were significantly associated with maturity of the animals and with diagnosed otitis. In healthy animals, a particularly low prevalence of the genus was found in Holstein cows, especially in the summer months, a finding perhaps correlating with the open, air-exposed ears of this breed. Pendutlous-eared zebu breeds and hybrids had higher levels of colonization, although this effect was more pronounced in humid regions, and was least in the dry north and west of the state. The most common species seen was M. sympodialis, which accounted for 47.1% of isolates from healthy cattle and 39.1% from cattle with otitis. In cattle with otitis sampled in summer, we found that the relatively thermotolerant M. sympodialis made up 80.8% of isolates. By contrast, during the winter the less thermotolerant M. globosa was the most common species from otitis, making up 56% of the isolates. Humidity and temperature may be the main factors explaining the epidemiology of Malassezia diseases and colonizations in both animals and humans.