Ringworm

Ringworm occurs worldwide and all types of animals can be infected. Animals whose hides and skins are used for leather manufacture are normally only affected by the Microsporum and Trichophyton species; the Epidermophyton species normally only infects humans. However, humans can also be infected by the other species, so farmers are often keen to treat infected animals to avoid infection themselves. Ringworm lifecycle Usually, ringworm only grows in the outer dead parts of the skin where the epidermis has keratinised. It will also grow in other areas where there is keratin, eg hair and nails/claws. The infection rarely spreads into the deeper living skin tissue. However, the fungus produces enzymes etc which diffuse into the living skin below, causing inflammatory and hypersensitivity reactions that are responsible for the development of characteristic circular lesions. Ringworm infection begins on the hair or skin surface where the threadlike tubes called hyphae develop from the spores. These hyphae penetrate into the hair shaft causing it to weaken and break leading to patches of hair loss and some degree of inflammation of the hair follicle and the surface of the skin forms a scab which separates away. As the infection progresses, spores are produced that are carried by fragments of hair as it breaks off, thus spreading the infection. The ringworm spores are transmitted from animal to animal primarily through direct contact. Consequently it is most prevalent when animals are kept in close proximity, eg when housed during the winter months. Ringworm spores can persist in the environment for up to two years, so re-infection can easily occur. Ringworm damage to leather On leather, ringworm appears as characteristic circular shaped lesions that are usually between 1 and 5cm in diameter and sometimes the grain surface may be slightly raised. In calves, ringworm is most commonly found on the face and back. In adult animals it is also found on the chest and legs. Scar tissue is not formed during ringworm infection, but the distorted hair follicle mouths do disfigure the grain surface of leather, thus rendering it useless for aniline production. However, because only the surface of the leather is affected, it is easily removed by correcting the grain and is concealed by finishing. Control of ringworm In healthy animals immunity towards ringworm develops and further spread of the infection is inhibited, although this process may take some time. Without treatment, it can take many months for the infection to subside and the lesions to heal. In young animals, or where the immune system is challenged by other diseases, infections can be persistent and widespread. Disinfection of sheds and yards that have housed infected animals is important, as is the isolation of infected animals to prevent spreading the disease. In the event of an outbreak, there are many highly effective proprietary topical fungicidal treatments available, usually in the form of sprays. However, for treatment to be effective, it must be continued for some time after the lesions have healed. Medication can be administered in the animals' feed. However, this form of treatment is prohibited in animals intended for human consumption. As ever, prevention is better than cure and there is now a vaccination for ringworm available that has proved highly effective in the control of the disease in domestic animals. Summary Ringworm, or dermatophytosis to give its technical name, is a highly infectious fungal disease of the skin that can cause disfigurement of the grain surface of leather. It can affect any animal, but in terms of importance to the leather industry, it is most prevalent on cattle hides.