HERD HEALTH
PIH-79
pork industry handbook
COOPERATIVE EXTENSION SERVICE • PURDUE UNIVERSITY • WEST LAFAYETTE, INDIANA
Environmental Sanitation and Management in Disease Prevention
Authors
George W. Meyerholz, USDA, Extension Service, Washington, D.C.
Jack M. Gaskin, University of Florida
Reviewers
David M. Bedell, University of Georgia
Glenn Elliott, Galivants Ferry, South Carolina
Dennard R. Hill, Seaford, Delaware
Wayne Rawson, Milledgeville, Illinois
Mounting evidence suggests that outbreaks of infectious diseases in swine are usually multicausal—a combination of bacterial, viral and parasitic agents influenced by stresses, nutrition, environmental factors and management practices. The interaction of these factors often determines if swine will have a disease and how severe it will be.

Practices that increase resistance and immunity, reduce stresses and decrease exposure to infectious agents will help reduce swine disease losses. Routine cleanliness, disinfection, and other sanitation practices reduce the spread of diseases. Isolation practices, the “all-in, all-out” system and other management practices can be used advantageously. Stresses such as chilling and dampness should be minimized to keep pigs comfortable, warm and dry. Proper diagnosis and total assessment of disease problems are necessary to design prevention and control programs to reduce losses. Medication and vaccination programs may be indicated. A total swine herd health program that fits individual needs should be adopted.

Sanitation is the foundation for an effective swine herd health program. The broad definition of sanitation is the employment of hygienic measures to promote health and prevent diseases. Sanitation is more than cleaning and disinfecting; it denotes practices that result in a reduction of microorganisms. The pork producer with knowledge of disease agents and methods of transmission can apply management strategy to maximize benefits of sanitation programs and disinfection.

Transmission of Infectious Diseases
Infectious diseases are transmitted by both direct and indirect contact. Some diseases such as atrophic rhinitis and mycoplasmal pneumonia are spread primarily by direct contact of one animal with another. Others are transmitted indirectly on clothing, hands, boots and shoes or through contamination of feed, water, vehicles, soil, bedding, air, utensils and premises. Leptospira and other disease agents may be carried from one premise to another in streams. Rodents also may be a factor. Birds have been shown to transmit TGE and salmonellosis. External parasites and insects may also transmit disease.
Swine that recover from infectious diseases may harbor organisms, shed them for varying lengths of time and serve as a source of infection for other swine. Swine dysentery, pseudorabies and brucellosis are examples of carrier state diseases. Diagnostic testing and other methods of identifying carrier animals may be desirable to eliminate diseases from the herd.

Stresses of various types may affect a pig’s resistance and ability to produce immunity. Stresses increase corticosteroid secretions which interfere with defense mechanisms by reducing the number of certain white blood cells and interfering with antibody formation.

Survival of Organisms
Some organisms can survive for long periods of time in the environment, sometimes for years. However, survival times are extremely variable. When a specific disease problem occurs in the herd, the survival time, carrier state in the animal, and method of transmission should be assessed to identify special sanitation requirements needed to aid control and prevention. The choice and strength of a disinfectant can be influenced by specific disease problems. For example, the spore-forming organism that causes anthrax is extremely resistant to common disinfectants. Also, the tuberculosis organism and certain viruses may require special consideration. Parasite eggs are extremely resistant but thorough cleaning will remove most of them from the environment and reduce numbers significantly.

Pathogenic (disease-causing) organisms usually favor a temperature close to that of the host animal. However, TGE virus is fragile in a warm environment and seems to survive better in a cold or frozen climate. This accounts for the increased prevalence in winter. Parasite eggs have been shown to hatch at temperatures as low as 40-50°F. These and other examples indicate that cold is not usually a deterrent to survival or transmission of disease agents. In fact, low temperatures prolong the lives of most organisms and freezing actually preserves bacteria, mycoplasmas and most viruses.

The ultraviolet rays of the sun are very effective in destroying infectious agents. However, they do not penetrate deeply and do not pass through glass. Direct sunlight
Cooperative Extension Work in Agriculture and Home Economics. State of Indiana. Purdue University and U. S. Department of Agriculture Cooperating. H. G. Diesslin, Director, West Lafayette, IN. Issued in furtherance of the Acts of May 8 and June 30, 1914. It is the policy of the Cooperative Extension Service of Purdue University that all persons shall have equal opportunity and access to its programs and facilities without regard to race, color, sex, religion, national origin, age or handicap