Why do people who work with animals at Rutgers need to knowhow to do so safely? Are animals at Rutgers more dangerous than your pets at home or animals on private farms? The answer is "YES" and "NO".
House pets and farm animals are certainly subject to the same diseases as research animals. However, a number of factors may increase the hazard of working with animals in a research setting. The great majority of animals used in research at Rutgers are rats, mice and other rodents bred especially for research, and these animals are unlikely to harbor harmful diseases on arrival. Rutgers investigators do work with other types of animals, whose health status is not so well defined. These include wild animals, rodents from other research facilities and livestock. Free-ranging animals such as birds, rodents and raccoons may introduce diseases into research facilities or expose animals on pasture. High population densities, frequent introduction of new animals, and the exchange of animals between research institutions increase the potential for disease in research animals. The way we use research animals is also an important difference between research animals and pets. Animal research may involve the use of hazardous substances such as carcinogens, toxic chemicals and radioactive isotopes. In addition to diseases, animals may inflict injury by biting, scratching, kicking or other activities. While you may be used to handling your dog at home, you probably aren't used to giving her injections or restraining her to collect blood. You are also likely to work with types of animals that you have never been close to before. You can get hurt by a horse or a rat if you don't know how to work with them. On the other hand, you can work safely even with wild animals if you know how to do it properly.
This brochure discusses some dangers you could encounter in working with research animals, and describes safe practices to follow to prevent these dangers from affecting you.
A zoonotic disease, or zoonosis, is an infectious disease which can be transmitted between humans and animals. Of the hundreds of zoonotic diseases known, a handful are of concern in the research animal facility. Modern animal production techniques and animal facility operating procedures are designed to minimize the threat of zoonotic diseases, both to personnel and valuable animal colonies. When human infection does occur, it often results from the failure to follow long established, well accepted procedures. Serious cases of human disease in recent years have resulted from infection with well-recognized zoonoses, "new" or previously unrecognized diseases, and "old" diseases which had not caused problems for years.
Prevention and control of disease in a research facility involves everything from vendor selection, animal receiving, quarantine, facility design, animal housing, personnel traffic patterns, sanitation practices, vermin control, veterinary care and necropsy. When working with seemingly healthy animals for long periods, it is easy to become complacent, take shortcuts, and ignore safety recommendations. Events of the past years remind us though that complacency can be costly, even fatal.
A detailed discussion of individual zoonotic diseases is beyond the scope of this pamphlet. The basic principles outlined below are designed to protect you from diseases that may be present in the animals you work with. The case histories that follow will give you a sense of what happens when these principles are not followed.
Women who are pregnant can work in animal facilities, but certain tasks may present a hazard to the unborn fetus. Women who become pregnant should notify their instructor/supervisor. The instructor/supervisor should consult with a University Health Services physician to review the duties of the pregnant woman.
Toxoplasmosisis a disease acquired from cats that if acquired by a pregnant woman during pregnancy can cause birth defects and other disorders in an unborn fetus. It is recommended that pregnant women not work with cats in a laboratory or farm setting. This includes not working in barns where cats are kept for pest control.
As discussed above, there are a number of ways in which you can be injured by animals. Bites, scratches, kicks and other injuries are avoided by knowing the species you work with, using proper equipment, and using tranquilizers and anesthetics where appropriate.
Working with animals often involves heavy lifting. Back injuries are amongst the most common causes of lost work-time by animal workers, both in laboratory animal facilities and in farm buildings. Proper lifting technique will help avoid back injuries.
Students will not generally work with the most hazardous chemicals, biological agents and radiation sources. However, any person who does should follow all instructions about safe work practices and observe all warning signs. Pregnant women should consult a physician about the advisability of working with hazardous agents.
Allergies may be an annoyance or may keep you from working with some species of animals. Consult a physician if you think animal allergies are a problem. If you wear work clothing to class or home, you may expose others to animal allergens.
Promoting safe behavior is a frustrating proposition. People unfamiliar with hazards associated with an activity are not easily convinced that a practice is hazardous, especially when they see it done repeatedly with no consequences. Safety experts on the other hand, have knowledge or experience of infrequent problems with sometimes serious consequences. The following case histories are presented as examples of what could happen in working with animals when recommended practices are not followed. All of these cases actually happened. Most did not occur at Rutgers and they did not all happen in a research setting, but they are illustrative of potential problems in working with animals. The case histories are not meant to alarm you, but to help you understand why the recommendations in this pamphlet are important.
A veterinary college acquired seven Holstein calves from two local dairies for a student laboratory. Thirty-five students worked with these calves in a lab session before the instructor was informed that all of the animals were infected with Cryptosporidium. Subsequently, 8 students developed gastrointestinal illness. Cryptosporidiumoocysts were found in fecal samples of 50% of those students tested. Affected students experienced fever, headache, nausea, diarrhea and vomiting. Most of the students recovered quickly with no treatment. One had severe diarrhea for two weeks. Another required hospitalization for severe dehydration.
Comment:Cryptosporidiumis a zoonotic, protozoan parasite (similar to coccidia). It was once thought to be rare in animals and not of much significance in people. It is recognized to be almost ubiquitous in young ruminants (e.g. calves, lambs, kids). In people with a normal immune system it generally causes short-term diarrhea. In people who are immunocompromised (e.g. from AIDS or cancer chemotherapy), it causes a prolonged, life- threatening disease. In 1993, it caused widespread disease when it contaminated the Milwaukee, Wisconsin water supply. There is no known effective treatment.
Precautions:Healthy (immunocompetent) people should practice good personal hygiene when working with young animals, especially calves. Cryptosporidiumis persistent in the environment and could be spread by contaminated clothing. Infants and immunologically compromised adults should not handle animals with diarrhea. If you are immunocompromised, it is strongly recommended that you do not work with calves, lambs, kids or deer fawns.
In 1991, an 80 year old Ohio woman died of tetanus despite intensive hospital care. She died two weeks after receiving a wood splinter from a forsythia bush. She had no history of tetanus vaccinations, despite frequent doctor visits for other problems.
Comment:This is obviously not a research related case, and it does not even involve animal exposure. However, it is instructive on several points. Tetanus can be a fatal disease. The vaccine is highly effective in preventing the disease and generally gives protection for 10 years. Wounds such as the one received in this woman are frequently minor and may not be sufficiently severe for the patient to seek medical attention. Everyone should keep their tetanus vaccination status current. Rutgers Student Health Service charges for tetanus vaccination unless it is given in conjunction with an injury, in which case there is no charge.
In 1989, a 23 year old employee at a private research institution in New Jersey was hospitalized for viral meningitis. Her symptoms included fever, myalgia, malaise, fatigue, severe headaches, chest pain, difficult breathing, coughing, vomiting, abdominal pain and hair loss. Her illness lasted 8 weeks. The cause of her illness was determined to be viral meningitis (inflammation of the lining of the brain and spinal cord) caused by lymphocytic choriomeningitis virus (LCM).
The patient worked at a research laboratory that develops drugs and diagnostic tests in animal models. Part of this effort involved maintenance of a tumor cell line that could not be maintained in tissue culture. For 20 years the tumor cells had been maintained by injection into the cheek pouches of hamsters. (hamster cheek pouches are immunologically protected, and tumors will grow there without rejection.) For the past few years the tumor was injected into "nude" mice. (Nude mice, like AIDS patients, are deficient in T lymphocytes and do not reject transplanted tissues, even from other species.) Investigations revealed that the tumor line had been infected with LCM virus since at least 1975. Almost 20% of the cell lines maintained by the company were infected. Apparently, the switch to using nude mice had increased the exposure of employees. Of employees who worked with nude mice, 26% had evidence of infection with LCM. Several other workers had had illnesses that were likely due to LCM. Actvities most associated with infection were changing bedding, changing water bottles, and cleaning cages.
Comment:LCM is one of the few zoonotic diseases (diseases people get from animals) of concern in modern rodent research facilities. Common in wild house mice, it has been eliminated from commercial rodent breeding colonies. It can be introduced into research facilities by wild mice, or by the introduction of infected tissues. Steps used to prevent introduction of LCM into a research facility are standard accepted procedures in well run programs. They include exclusion of wild rodents, careful evaluation of animals and animal tissues from other than commercial breeders, and testing programs within the facility.
In April 1980, an unusual illness was recognized among faculty, laboratory workers and staff of a medical school. The illness was remarkably uniform in its clinical manifestations - notably high fever (up to 105 degrees F), shaking chills and absence of respiratory signs. The disease was determined to be Q fever, caused by the organism Coxiella burnetii. The source of the infection was pregnant sheep used for research. In a six month period, clinical infections were confirmed in 65 people. Blood tests showed that a total of 137 people were exposed. Of these, only 41 were directly involved in working with the sheep. The remainder of exposed people worked along routes followed by sheep carts or were exposed in other ways. As a result of this outbreak, all sheep research was moved to a research farm distant from the medical center.
Comments:Q-Fever is a rickettsial disease of ruminants such as cattle, sheep and goats (a rickettsial disease you are more familiar with is Rocky Mountain Spotted Fever). It is very common in these animals to the point that it is difficult to find herds free of it. Milk pasteurization kills the organism in cow's milk. At the time of parturition (giving birth), infected animals shed high numbers of organisms in the placenta and fetal fluids.
In a production-type sheep operation, with movement of animals in and out of the flock, it is not practical to eliminate Q-fever from the flock. The Rutgers flock is infected.
The acute (immediate, short term) illness in people is treatable with antibiotics, but often goes unrecognized. Chronic, long-term complications include infection of heart valves. People with pre-existing heart conditions are at increased risk of chronic infection.
Sheep have been associated with outbreaks of human disease in medical school settings because sheep are a popular animal model for obstetrical research. The combination of pregnant sheep, non-animal workers and especially hospital patients is a setup for a problem. This demonstrates the importance of separating animal use areas from "people" areas. At Rutgers, sheep are used only at the farm and in animal facilities.
People who work with sheep receive instructions on procedures to follow when working with them. Since our housing and research arrangements provide good separation from non-animal workers, our emphasis on prevention focuses on alerting people who might be at risk of chronic Q-fever complications. Persons who are immunocompromised or who have a history of heart disease (e.g. rheumatic fever, heart surgery) should consult a physician about the advisability of working with sheep and other ruminants.
A 28 year old woman, working as a dog groomer at a veterinary hospital, was bitten by a dog. The wound was washed with surgical iodine solution and bandaged. Three days later, the woman left work because she felt ill and had pain at the site of the bite. Within 12 hours she had two grand mal seizures, collapsed and was hospitalized. During her hospitalization, she was treated for septicemia (blood infection) and kidney failure. She eventually recovered without further complications. Two years prior to this illness, the woman had her spleen removed for medical reasons.
Comments:This patient became infected with a bacterium formerly called "DF2", and now classified as Capnocytophaga canimorsus. This bacterium is commonly found in the mouths of normal dogs and is probably a common contaminant of dog bite wounds. "Normal people" rarely experience problems. The organism can cause a serious, potentially fatal systemic infection in people with impaired defense mechanisms. Absence of a spleen and alcoholism have been associated with many cases. In such patients, even intensive antibiotic therapy may not be able to control the infection. The rapid onset of signs seen in this case is typical. One author suggests that all splenectomy patients should be hospitalized for observation following dog bites.
Persons who have had their spleen removed are urged to consult with their physician about the advisability of working with dogs or cats, in any setting.
An undergraduate student took a course in which live animals were used to demonstrate common biological principles. Prior to the course, the use of animals was reviewed by the Animal Care and Facilities Committee to assure that the proposed procedures were appropriate. The instructor followed accepted procedures of animal use and the student followed basic principles of working safely with animals. The student learned how to handle several types of animals safely, and gained an appreciation of the variability of biological systems. The instructor's innovative teaching methods were cited as a major factor when she received tenure that year. The student got the flu from her lab partner and missed a week of class.
Comments:When students follow accepted safe practices, working with animals can be a rewarding part of a college education with minimal risk of injury or illness. In fact, a student is probably more likely to acquire an infectious disease from another person than from an animal.