Prevention

Methods of preventing the transmission of infectious material from animals and poultry to agricultural workers mirror in many ways the safety techniques for protection from chemicals, trauma and other hazards (see Chapter 6). The methods are summarized in Table 27.2.

Key to the prevention of the transmission of animal disease to humans is the proper processing of food products. This includes proper cook times and temperatures, adequate refrigeration, and appropriate transportation, processing, and stocking in stores.

Personal protective equipment includes hats or head coverings and protective coats or uniforms that can be laundered and left at the plant or farm. Boots should also be cleaned and left at the farm or plant. Especially in poultry operations, protective particulate masks may be necessary. In some

Table 27.2. Methods for preventing the infection of agriculture workers from poultry or animals.

Proper food processing

Personal protective equipment (Chapter 6)

Masks, hats, coveralls, gloves Protective physical barriers Policies and procedures Veterinary herd monitoring Rapid culling

Public health monitoring for disease trends and epidemics

Medical monitoring

Immunizations (Chapter 25)

Education and training (Chapter 5)

Development of technologies to prevent transmission

Hygiene

Hand washing Government regulations and monitoring (Chapter 4) Supervision

Source: Data from Davies and Wray (7), Fone and Barker (8), Meslin (9), Gardner (10), and Richardson et al. (11).

situations, especially when handling urine or feces, protective gloves are important (see Chapter 6).

Protective physical barriers in farm, ranch, or plant design allow for the raising or processing of food products without actual contact of humans with the animals or products. Built-in barriers, changing rooms, boot baths, and hand-free handling techniques allow for the safe and efficient handling of food.

In British chicken hatcheries, an aggressive combination of egg sanitiza-tion and handling methods was successful in decreasing zoonotic infections and diseases spread through flocks. Procedures included:

1. Design changes in incubators

2. Whole building ventilation systems

3. Control of dust, fluff, and aerosol production

4. Disinfection of surfaces and equipment

5. Improved handling of wastes (7).

Policies and procedures to limit or prevent physical contact with animals, feces, or urine prevent transmission. Rules prohibiting the consumption of food products on farms and ranches or on production lines are especially important. Not only can the production food product be infectious to workers, but food brought in by workers can become contaminated, which mandates eating areas for workers away from the livestock (7).

Aggressive veterinary monitoring of livestock can detect early evidence of disease outbreaks in herds. Similarly, public health monitoring of disease in humans can detect and appropriately treat epidemics of food-borne disease in humans and trace the source to the food-processing breakdown that caused the disease. Hazard analysis of critical control points (HACCP) is crucial to the prevention of infections in herds. Low cost, ease of performance, and rapidity of results are the key criteria for the tests, and are sometimes more important than the performance characteristics of sensitivity, specificity, and reproducibility. Field test kits are available for bacterial, protozoa, antibiotic residue, and other parameters of animal health (8,9,10).

Medical monitoring can detect early disease and prevent its spread to other employees, the food product, and family members. Pre-placement medical monitoring can identify people who are susceptible to infection, for example people with diabetes or immune diseases. In parts of the world where bovine tuberculosis is common, TB skin test monitoring can detect early infections and allow early treatment (8,9).

Immunizations are expensive, unavailable in many parts of the world, and only recommended for areas of high infectivity or occupations of high risk such as veterinarians. Three critical immunizations are tetanus, rabies, and influenza (see Chapter 25). Vaccines against salmonella, shigella, and other pathogens are in development or testing.

Training and education in proper handling techniques are important. Proper ways of herding, handling, and caring for animals and poultry can prevent infection and the transmission of infectious material. See Chapter 5 for details of education and training.

Research and the development of new techniques to prevent transmission are critical. For example, airborne dust has been discovered to be a carrier of pathogens in broiler breeder pullets (chicken pens). The use of an electrostatic space charge system has decreased the particle concentration and, in the process, decreased the potential of disease transmission to other chickens and to poultry workers (11).

Hygiene, both in the person and in the workplace, is essential in preventing the transmission of disease. For example, in many German piggeries workers must shower and change clothing when they enter and leave the buildings. This technique prevents the infection of the pigs with outside pathogens, the transfer of pathogens from one piggery to another, and the transfer of pathogens to the home environment. Especially important are the cleaning of machinery and the timely cleaning of animal and poultry urine and feces. Not only can urine and feces be infectious but they can attract insects that can spread pathogens. As in medicine, the most important hygiene procedure is aggressive hand washing for all persons handling food products.

In Louisiana, for example, alligator farmers must wear rubber boots and waders to protect themselves from pathogens (but not from bites, which can go right through the protective ensembles). Each day, the pens must be flushed and hosed off to remove the wastes that could harbor pathogens dangerous to the alligator colonies and workers.

Governmental regulations and oversight are important in providing standardization and systemization of methods and procedures to reduce the risk of infection to agricultural workers. Good regulations and oversight are evidence-based and consistent with sound agricultural methods (see Chapter 4).

It is not enough to have rules, regulations, equipment and techniques to prevent the spread of pathogens from animals and poultry to workers. Fair and consistent supervision by knowledgeable managers is critical to see that the proper equipment and supplies are used and that handling and hygiene rules and regulations are carried out.

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