EXAME MICOLÓGICO E ACOMPANHAMENTO CLÍNICO DE BOVINOS INFECTADOS PELA FORMA LATENTE DO Trichophyton verrucosum (BODIN, 1902)

Abstract

RESUMO -Com o objetivo de se determinar o período de latência da tricofitose bovina sob condições naturais de infecção, bem como testar a utilidade da escova de unha de uso humano, foram examinados 80 bovinos sadios, com menos de 3 meses de idade, que estavam em contato com animais doentes. O dermatófito Trichophyton verrucosum (Bodin 1902) foi isolado em cultivos micológicos de 32 animais (40 %), dentre os quais 25 foram acompanhados clinicamente durante 16 semanas; destes 22 adoeceram com sintomatologia característica entre duas e oito semanas após o primeiro exame. Três animais não adoeceram apesar de serem positivos. Os resultados denotam a importância da patogenia da infecção e dos animais infectados de maneira latente para os surtos de tricofitose bovina. Concluiu-se que 88 % dos bezerros adoeceram em até 8 semanas após a instalação da infecção. O uso da escova de unha constituiu-se em método válido de colheita de material para a detecção precoce da tricofitose bovina.Palavras chave: tricofitose, bovino, diagnóstico, latência.ABSTRACT -In order to establish the period of latency of bovine ringworm in natural infection and the applicability of a human nailbrush for its detection, 80 apparently healthy calves under 3 months of age and in contact with infected animals were examined. Trichophyton verrucosum (Bodin 1902) was isolated in mycological cultures from 32 animals (40%), of which 25 continued to be clinically examined during the following 16 weeks. It was observed that 22 of these animals developed ringworm lesions from 2 to 8 weeks after the first examination. Despite being positives in mycological culture, three animals did not develop any clinical sign of infection. The results have shown the importance of the infection pathogeny and latent infection for the epidemiology of bovine ringworm. In conclusion, 88 % of the calves developed clinical signs until up to 8 weeks after infection, and the hairbrush method was found useful for the early detection of bovine ringworm.

High Infection Rate of Trichophyton verrucosum in Calves from Central Italy

“…Based on the lack of any statistically significant support for the risk factors we examined, our results show that calves of any sex, breed, age, and of any of the farm condition considered are highly exposed to risk of T. verrucosum infection. With respect to results of comparable studies, the present infection rate is considerably higher than the 47.8% found in Jordan (Al‐Alani et al., 2002), 17.1–58.6% in Japan (Takatori et al, 1993), 25% in Spain (Cabañes et al, 1997), 32.3% in Iran (Khostravi and Mahmoudi, 2003), and 40–44% in Brazil (Ollhoff, 2003; Silveira et al, 2003). In Italy, total prevalence values previously reported from different cattle populations were 18.7% with T. verrucosum isolated in 26 out of 28 ringworm infected farms (Mantovani and Moranti, 1977), 4.5–19% (Moretti et al, 1998), and 48.7% (Galuppi et al, 2002).…”

“…In the present study, T. verrucosum was isolated from 80.4% of asymptomatic calves and results of a follow-up study revealed that T. verrucosum can remain on the skin of 88% of all apparently healthy calves for 2-8 weeks before clinical signs develop. In addition, in the same study, 12% of all apparently healthy calves did not develop skin lesions within 140 days after the first examination (Ollhoff, 2003). Therefore, some infected calves harbour the organism on their coat before there are visible signs of infection and it is possible that some of them have a degree of natural immunity that prevents develop-ment of lesions.…”

“…Sometimes, hair samples were inoculated on Sabouraud dextrose agar (Moretti et al., 1998;Takatori et al, 1993; Khostravi and Mahmoudi, 2003) or other standard solid media without nutritional supplements (Cabañes et al, 1997; Al‐Alani et al., 2002), and incubated at 26–30°C (Moretti et al., 1998; Takatori et al, 1993; Al‐Alani et al., 2002). However, it has been reported that as many as 17.1–40% of apparently healthy cattle in contact with infected animals may harbour T. verrucosum on their coats (Takatori et al, 1993; Ollhoff, 2003), and that the hairbrush technique represents the most useful method for the early diagnosis of bovine ringworm (Ollhoff, 2003). Moreover, T. verrucosum grows well at 37°C, is difficult to cultivate in normal dermatophyte media, and special media are needed for this purpose as all strains require thiamine, while approximately 80% require thiamine and inositol as nutritional supplements (Kane and Smitka, 1978).…”

“…Ringworm has been reported as one of the most important morbidity factors in calves (Svensson et al., 2003) and Trichophyton verrucosum is the dermatophyte nearly exclusively isolated from cattle, although Microsporum gypseum , Trichophyton mentagrophytes , Trichophyton rubrum , and Trichophyton simii have also been reported (Mitra et al, 1998). Cattle represent the natural reservoir of this zoophilic dermatophyte which occurs throughout the temperate regions of the world and has been isolated from cattle in Japan (Takatori et al, 1993), Spain (Cabañes et al, 1997), Jordan (Al‐Ani et al., 2002), Iran (Khosravi and Mahmoudi, 2003), Brazil (Ollhoff, 2003; Silveira et al, 2003), China (Ming et al, 2006) and others. There have also been some reports of isolation from sheep, goats, horses and camels (Khostravi and Mahmoudi, 2003).…”

Caracterização da microbiota por fungos filamentosos no tegumento hígido de bovinos de corte

“…T. verrucosum, a espécie mais comumente isolada de casos clínicos e adaptada ao bovino, foi isolado em baixas frequências (LONDERO et al, 1970;SILVEIRA et al, 2003). Todavia, essas frequências aumentam quando há contato com animais doentes ou presença de animais já recuperados da doença, os quais veiculam os conídios do fungo, atuando como disseminadores e perpetuadores da enfermidade (LONDERO et al, 1970;TAKATORI et al, 1993;OLLHOFF, 2003). Surtos de dermatofitose em bovinos, causados por T. verrucosum, têm sido observados no Rio Grande do Sul, afetando tanto animais adultos como jovens, durante os meses de outono e inverno, com prevalências que variam de 7,5% a 42,8% (PEREIRA & MEIRELES, 2007).…”