Disinfection and hygiene in the veterinary field and disinfection of animal houses and transport vehicles

Disinfection in animal houses means always a combination between cleaning and disinfection because the high amount of organic material present in such an environment will neutralize rapidly each disinfectant brought to the surface if no cleaning step had been done before. Depending on the kind of material, cleaning gives a 3 log reduction of total bacterial count on the surface and disinfection another 3 log reduction. This means that under practical conditions generally 103 cfu of bacteria remain per cm2 of surface, mostly sporeformers. The choice of disinfectant depends on the purpose of disinfection. In the case of notifiable diseases, it must be active against a defined pathogen. In the case of prophylactic disinfection, it must be active against a broad spectrum of microorganisms. Only disinfectants which are tested for their activity on surfaces which are representative for animal houses e.g. wood should be used, otherwise the failure under practical conditions can be predicted and work, as well as money, will be wasted. The optimal temperature for the liquids used in cleaning and disinfection is 40°C and the optimal temperature of surfaces is 20°C. Colder surfaces require higher concentrations of active substances in the solution, below 10°C the effect of practical disinfection is incomplete. Low air humidity and high air velocity have a negative influence on the action of most disinfectants on surfaces. The amount of disinfectant necessary to disinfect a surface in an animal house is at least 0.4 l/m2. Transport vehicles are very difficult to disinfect, especially in winter-time. They should be cleaned with hot water, the remaining liquid should be removed by a suitable vacuum cleaner and the concentration of the disinfectant should be elevated at least for the factor 3. Mechanic action will improve the disinfecting effect in vehicles as well as preliminary disinfection prior cleaning.