Causes and prevention of dermatophilosis in cattle

The causative agent of dermatophilosis (also known as rain scald or streptothricosis) is the bacterium Dermatophilus congolensis, a Gram-positive facultatively anaerobic organism belonging to the actinomycetes. The infection affects cattle, horses, sheep, and humans. The disease manifests as crust-covered lesions and matted hair, especially on the back and flanks of the livestock animals.

Predisposing factors are required for the bacterium to penetrate the skin's protective barrier. These include prolonged skin hydration, insect bites, and damage to the integument. Flies act as mechanical vectors for zoospores and cause skin injuries that facilitate bacterial penetration. In addition, a deficiency in certain nutrients, such as zinc and vitamin A, weakens the protective functions of the skin.

The bacterium is capable of surviving for a long time in dry crusts and scabs in the external environment. The disease is zoonotic in nature and can be transmitted to humans through direct contact with sick animals or contaminated materials.

The diagnosis is established based on clinical signs, confirmed by microscopic examination of smears from the lesions or by bacterial culturing. To prevent the spread of the disease, it is recommended to isolate sick animals, remove and dispose of infected material, as well as clean and disinfect equipment using soap, water, chlorine-based solutions, or quaternary ammonium compounds.

Currently, there is no commercial vaccine against bovine dermatophilosis, so prevention is based on minimizing predisposing factors and maintaining hygiene. With appropriate treatment and care, most animals recover within two to four weeks.