Testicular immunology
Mumps is a viral disease which causes swelling of the salivary glands and testes. The mumps virus lives in the upper respiratory tract and spreads through direct contact with saliva. Prior to widespread vaccination programs, it was a common childhood disease. Mumps is generally not serious in children, but in adults, where sperm have matured in the testis, it can cause more severe complications, such as infertility.
Mites of livestock
The clinical manifestation of infestation with psoroptic mites is usually called mange and sometimes scabies, but the skin disease of sheep caused by "Psoroptes ovis" is often known locally as sheep scab. This species may affect its hosts severely enough to reduce their gain in weight. Costs to farmers of controlling sheep-scab in Britain were at £8 million (US$12 million) annually in 2005. Transmission between hosts is readily accomplished by contagion during flocking contact and also on fomites such as scraps of sheep's wool because these relatively large and robust mites can survive for one to two weeks off their host. "Psoroptes ovis" infests the superficial layers of the skin. Irritation of the outer skin by the mite's mouthparts and saliva results in a complex form of cutaneous hypersensitivity and inflammatory exudation of serum and fresh cells. The mites feed on this moist exudate. The skin loses its hair (depilation) at the sites of infestation and this may be extensive. As a result of the movement of the mites into areas of fresh skin, large scabs accumulate on the raw skin left behind. The mites cause intense pruritus (itching). In cases of heavy infestations, the host grooms compulsively, aggravating the depilation, and it may become mentally distressed. "Psoroptes ovis" infests sheep worldwide and can be a serious welfare and animal-production problem for sheep farmers.
Infestations of cattle with mites of the similar genus "Chorioptes", in combination with "Sarcoptes" mite infestation, has been shown to cause a failure to gain body weight by 15.5 kg to 37.2 kg over a two-month period compared to cattle without the mites.