Occupational Health Zoonotic Diseases

Division of Research and Graduate Studies

Zoonotic Diseases

Tetanus
The Public Health Service Advisory Committee on Immunization Practices recommends immunization against tetanus every 10 years. An immunization is also recommended if a particularly tetanus-prone injury occurs in an employee whose last immunization was more than five years ago.

Every employee should have up to date tetanus immunizations. If you need a tetanus immunization or have questions regarding this issue, please contact the University Health Center, telephone 2322.

Leptospirosis
This is a contagious disease of animals and humans due to infection with Leptospira species. The usual mode of transmission is contact with infected urine or the ingestion of urine-contaminated food or water or through a skin break.

Clinical symptoms may be severe, mild or absent and may cause a wide variety of symptoms including fever, icterus and general discomfort.
The disease can usually be treated successfully with antibiotics.
Dogs and domestic animals are the commonly infected laboratory animals. Wild rats are also commonly infected.

Human Allergies to Animals
Allergy to animals is common and is therefore one of the most important occupational problems for workers exposed to animals.

Allergies can show up in a number of ways including:

Allergic rhinitis (a condition characterized by runny nose and sneezing similar to hay fever)
Allergic conjunctivitis (irritation and tearing of the eyes);
Asthma
Atopic dermatitis (a skin condition caused by contact with a substance to which an individual is allergic).

Allergy to animals is particularly common in workers exposed to animals such as cats, rabbits, mice, rats, gerbils and guinea pigs.

There is still some controversy about exactly what substance causes the allergy in certain individuals. Previously it had been thought that most allergies were caused by dander and debris from the skin and fur of an animal. More recent studies seem to suggest that exposure to animal urine may occur either through direct urine contact with skin, or more commonly by inhaling dust from the bottom of a cage that has been contaminated with urine or fecal material.

Various studies show that between 15 and 20 percent of workers exposed to animals will develop some symptoms of allergy. This percentage may be even higher since some people are forced to leave their jobs because of the severity of the allergies they develop. Most of these reactions are of the allergic rhinitis and allergic conjunctivitis type; less than half will actually be asthma.

People who have a prior personal or family history of asthma, hay fever, or eczema will be more likely to develop asthma after contact with animals, but they do not seem any more likely to develop rhinitis and conjunctivitis than do people without previous personal or family history.

Allergy symptoms can develop anywhere from months to years after a person begins working with animals.

A majority of the individuals who are going to develop symptoms will do so within the first year.
It is extremely unusual to develop symptoms after more than two years of animal contact.

It is necessary that everyone exercise certain routine precautions to prevent animal allergy. These safeguards should not be focused only on people with atopic history.

Individuals should work with animals in extremely well-ventilated areas to prevent build up of various particles in the air.
Workers should always wear gloves and laboratory coats to prevent direct exposure to the animals. (This applies to animal urine as well as to animal dander.)
Cages should be changed frequently to prevent inhaling contaminated material.
Masks should be worn during the changing of cages.

Despite the best preventive techniques, some individuals will develop allergies after contact with laboratory animals. Rarely, this will be so severe that a person is forced to change his line of work. More commonly, allergy can be controlled with the increased use of masks while working with animals and the possible use of antihistamines.

Desensitization therapy has been done for some individuals, but this is not as effective for animal allergies as it is for some other types of allergies. Certainly anyone with significant symptoms related to animal exposure should obtain medical advice.

Ringworm (Dermatomycoses)
Many species of animals are susceptible to fungi that cause the condition known as ringworm. The skin lesion usually spreads in a circular manner from the original point of infection, giving rise to the term "ringworm." The complicating factor is that cats and rabbits may be asymptomatic carriers of the pathogens that can cause the condition in humans.

In humans the disease usually consists of small, scaly, semi-bald, itchy, grayish areas with broken, lusterless hairs.
Transmission of the disease is by direct contact with an infected animal. Careful personal hygiene is the best method of prevention.
One should obtain medical assistance if lesions are noted.

Toxoplasmosis
Toxoplasmosis is a disease caused by an organism called Toxoplasma gondii. Approximately one-third of the U.S. population has had this disease at some time.

Usually this disease is quite mild and may be mistaken for a simple cold or viral infection.
Swollen lymph nodes are common, as are mild fever, general washed out feeling and mild headaches. More serious illness can occur involving tissues of the lungs, heart, brain or liver.

People acquire toxoplasmosis by eating meat that is raw or undercooked, or by contact with feces of an infected cat. In addition, this organism can be passed on to the fetus of a pregnant woman if she becomes infected during her pregnancy. At any one time about one percent of all cats will be shedding toxoplasma oocysts in their feces.

There are two situations in which toxoplasmosis can be extremely serious:

Individuals whose immune systems are not working properly can contract a severe form of the disease. This category would include people with AIDS or a positive blood test for the AIDS virus, and people on medications or with other serious illnesses that suppress their immune systems.
An infection with toxoplasma can severely damage an unborn child if the mother gets an acute infection during her pregnancy. The result can be miscarriage, stillbirth or various congenital defects.

The disease is more serious if passed on to the fetus early in pregnancy, but it is more common for the illness to be passed on later in pregnancy.

Certain simple precautions will prevent a person from acquiring toxoplasmosis:

Meat should be thoroughly cooked before it is eaten.

It is extremely important that cats be fed only commercial cat food or well cooked meat.

Cats acquire the toxoplasma organism by eating raw meat or wild animals that have been infected with the organism. The cat then excretes an egg form in the feces that does not become infective for approximately two days, but can persist for quite some time in the soil after that time.
The litter box of a cat who is outside should be changed daily.
When a woman is pregnant, she should avoid any contact with cat litter and cats who have been allowed to roam outdoors.
It is University policy that pregnant women should not be allowed to work with cats in the laboratory setting. Animal care workers who have been assigned to cleaning cat cages should be reassigned to other jobs during pregnancy. Workers who are exposed to cats in other ways would do best to avoid this exposure.

Q Fever
Q fever is a disease caused by a micro organism called Coxiella burnetii. It can be acquired by inhaling contaminated particles from infected sheep, goats, or cattle.

Especially high concentrations of these infected materials exist in animals at the time they give birth, so particular care needs to be used in handling newborn animals, placental tissue, amniotic fluid, blood or soiled bedding.

Individuals who handle young sheep, goats, or cattle up to six months of age and those who participate in the routine care of sheep or goats are at higher risk for contracting the disease.

Q fever is extremely contagious and has been reportedly spread by aerosol. In most cases the disease acts like an acute illness that could be mistaken for influenza.

A person might have high fevers up to 104^o or 105^o, accompanied by general malaise, significant muscle aches and pains, and frequently a cough.
Up to half of the individuals who develop this acute disease will have a pneumonia that can be seen on chest x-ray. A large number of people will also develop hepatitis, an inflammation of the liver.
In most patients the disease is self-limiting and will resolve on its own after 10-14 days.
In older or ill individuals, this acute illness may take one to two months to resolve. Even though it will resolve on its own, it is generally better to treat the disease with an antibiotic called Tetracycline to reduce the duration of fever.
It is extremely important that an employee who works with sheep or goats who develops an influenza-type infection mention to his physician the possibility of Q fever. (This is not something that would be routinely thought of and the diagnosis could be missed.)
Less than one percent of infected individuals develop a chronic infection with Q fever organism. This manifests itself as endocarditis, which is an infection in the valves of the heart that is nearly always fatal.
Ninety percent of people who develop chronic infection have some previous heart valve problem. Therefore, people who have congenital heart disease, prior heart valve disease or who have a chronic immuno-compromised state should not work with infected animals at the time of parturition.
It is best that these individuals not work with sheep, goats or cattle at all. Immuno-compromised individuals would include persons with AIDS or a positive blood test for the AIDS virus, and people who take medications or have certain chronic diseases.

A number of procedures should be followed to limit the spread of Q fever.

Laboratories using sheep, cattle and goats and animal care areas housing these animals should be strictly off limits to anyone who does not have a specific need to be there.
Gloves should always be used in handling these animals.
It is important that animals be transported carefully to avoid infecting others besides laboratory personnel.
Potentially contaminated surfaces should be decontaminated with dilute solution of chlorine bleach or dilute solutions of lisle. These organisms are quite resistant to destruction and many ordinary methods of disinfecting will not be adequate.
It is extremely important that laboratory doors be kept closed when experiments are in progress.
Employees working with potentially infected tissue need to wear protective clothing that is not worn outside the area.

Rabies
Rabies is a relatively rare but devastating viral disease that can result in severe neurologic problems and death. Most cases of rabies occur in wild animals, although any mammal can contract the disease. It is virtually unheard of in common laboratory animals, with the exception of dogs and cats. All bites of any type should be reported immediately to one's supervisor.

Non-Human Primates

A large number of illnesses can be passed from non-human primates to man and from man to non-human primates, so it is extremely important that animal workers exercise caution in handling of monkeys.

Protective clothing should always be worn. This clothing should NOT be worn outside animal areas.
Surgical masks covering the nose and mouth should always be worn when in contact with primates.
Animals should be handled only while wearing bite-proof gloves.
Ideally, animals should be anesthetized before procedures are done.
Employees should not work when they are ill since they may be more susceptible to illnesses transmitted from the monkey and may transmit disease to the monkeys.
Careful personal hygiene must be scrupulously maintained by all those exposed to non-human primates.
Any scratch or bite must be immediately reported to the laboratory supervisor.

There are two specific illnesses that deserve separate mention, but these are not the only illnesses that can be contracted from monkeys.

Non-human primates are very susceptible to tuberculosis. All individuals who work with non-human primates must be tested for tuberculosis semiannually. This involves a skin test for most individuals and an x-ray for those who have had previous positive skin tests.
Herpes B. or Herpes simiae causes a minor illness in old world monkeys but can cause fatal illness in humans. In monkeys it resembles cold sores like the lesions caused by herpes simplex in humans. In man it causes severe neurological disease, frequently followed by death.
Fortunately, transmission of this disease to humans is rare. It is mandatory that bite-proof clothing be worn and that a supervisor be notified about any bites or scratches.
Medical care must be obtained
Any wound should be carefully cleaned
An additional cleansing with chlorine bleach solution (diluted 1 to 10) needs to be used to kill any viruses present in the wound.
Once a wound has been properly treated, any unusual changes that develop later need to be promptly reported. Symptoms of herpes B infection include blisters at the wound site and pain radiating away from the wound.
Careful adherence to safe handling procedures is the most important step in preventing illnesses.

All persons working with primates at Kent State University must have regularly scheduled Tuberculosis tests and a pre-exposure serum sample. The serum sample will be stored and kept for possible future reference in the event of illness. Principal investigators are responsible for seeing that this requirement is adhered to.

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