we share a world with animals, it shouldn't surprise us that
we also share some diseases. This may be especially true in
rural areas and on farms where contact with animals increases
the risk. Infectious diseases transmissible between humans
and other animals are called zoonoses, or zoonotic diseases.
About 40 zoonotic diseases are found in Iowa. The risk to
humans depends on the kind of disease and type of exposure.
diseases have played a role in the development of society. For
example, five of the 10 plagues described in the Bible probably
were zoonoses. The first plague was related to water pollution,
the third and fourth were spread by gnats and flies, and the
fifth and sixth were anthrax infections that caused boils and
Death, or Plague, ravaged Europe and Asia between the 14th
and 17th centuries. It killed one quarter to a third of the
population, most of which lived on farms or in small communities.
Plague is caused by the bacterium, Yersinia pestis, which
is transmitted from rats to humans by fleas.
many lives were lost during World War I combat, the Spanish
Flu epidemic of 1918-1919 also killed many soldiers. In fact,
more American soldiers died from this influenza than from
combat injuries. The Spanish Flu killed an estimated 40 million
people throughout the world, mostly children and young men
and women, and led to the end of the war. The Spanish Flu
was later renamed Swine Flu when the virus was discovered
to have come from hogs. Fear of a similar recurrence prompted
the massive Swine Flu vaccine program in the United States
when the virus was isolated from a dead soldier at Fort Dix,
New Jersey, in 1976.
diseases continue to be a threat, but more knowledge has brought
about improved sanitation and development of antibiotics,
vaccines, and other drugs to battle them. Prevention, however,
requires constant attention to protect ourselves, our families,
and our communities.
This disease is familiar to Iowans and it causes great fear
because rabies is always fatal once symptoms begin. The
last human death from rabies in Iowa was in 1951, caused
by rabid dogs. Increased public awareness, mandatory rabies
vaccination of dogs, and control of stray dogs by enforcement
of leash laws, significantly have reduced the risk of rabies.
The greatest risks of rabies today follow cat and skunk
bites, and oral examination of salivating cattle by farmers
and veterinarians. Anywhere from 15 to 50 or more people
need post-exposure rabies treatment each year in Iowa.
and brucellosis. Thanks to the cooperation of Iowa farmers,
the organisms in animals that contribute to these diseases
in humans have been almost eliminated from Iowa livestock.
The organisms are killed by cooking and pasteurization of
Once a common human disease in the United States, trichinosis
is transmitted by infected pork and the meat of some undercooked
wild game. It has virtually disappeared because farmers
have participated in a program to cook all garbage and pork
trimmings fed to their pigs. Without cooking, these wastes
would cause trichina infection in pigs and produce disease
in humans who eat under-cooked pork.
This disease is a fungal infection of the skin on both humans
and animals. It is transmitted easily by direct contact.
Giardia is a water-borne protozoan, a microscopic, single-celled
animal that infects the gut of both animals and humans.
It is passed in the feces and can be carried in contaminated
water. Giardiasis can cause severe gastroenteritis with
fever, nausea, and abdominal pain, which may persist for
several days or more.
disease. This zoonotic disease is mentioned because
it is a much talked and written about disease, even though
few human cases have been reported in Iowa. Lyme disease
in people and animals usually is seen as an arthritis, but
may cause heart irregularities and neuralgic problems such
as headaches, dizziness, and facial paralysis. The signs
may begin soon after infection, become chronic, or be delayed
for months or even years.
Lyme disease is caused by a spiral-shaped bacterium similar
to that of leptospirosis and syphilis, and is transmitted
by deer ticks. Dogs, horses, cattle, deer, and other animals
are susceptible to Lyme disease.
other zoonotic diseases also are a threat to animals and humans,
it's important to recognize that these diseases can be prevented
by sanitation, personal hygiene, and proper animal health care.
The following safe practices can help prevent and control health
risks associated with zoonotic diseases.
a safe water supply. Make every effort to provide safe
drinking water to family and animals alike. Wells must be
properly constructed to protect against contamination from
livestock, human, and wildlife wastes. Consider chlorination
or connecting to a rural water system as a way to insure
safe water supplies.
sanitary waste disposal. Dispose of waste in approved
ways. Many diseases can be carried in animal wastes that
leak into the water supply, or from the bodies of dead animals
not disposed of properly.
meat safety. People who home-slaughter hogs or make
pork sausage with meat from deer and other game animals
are advised to cook, smoke, freeze, or otherwise cure meat
thoroughly. This will kill trichina larvae that may be present
in the meat.
contact with diseased animals. Ringworm can be prevented
by treating cases in pets and livestock, as well as people,
so as not to be a source of further infection. Wear clothing
that prevents skin contact with ringworm lesions. Keep stalls,
stanchions, cages, and housing clean because ringworm fungi
survive and grow in dirt, debris, and contaminated bedding.
All cats and dogs should be vaccinated against rabies.
Cattle that salivate excessively should be suspected of
having rabies and handled accordingly. Do not keep wild
animals as pets and avoid animals that exhibit strange
ticks. When you are in a tick-infested area, remove
ticks from yourself and your animals frequently to prevent
infection with Lyme disease and other tick-borne diseases
such as Colorado Tick Fever and Rocky Mountain Spotted Fever.
Wear a long-sleeved shirt, tuck pantlegs into socks, and
use tick repellent.
milk. Pasteurization kills bacteria that can cause tuberculosis,
brucellosis, Escherichia coli 0157, listeriosis, salmonellosis,
and other diseases. Never drink raw milk.
animal health and environmental health on the farm translates
into better health and safety for the farm operator, employees,
and members of the family.
much do you know?
many zoonotic diseases are found in Iowa?
zoonotic disease was Black Death better known as?
is a parasitic disease of pigs and people that is prevented
and eating garlic
can Lyme disease in humans be prevented?
answers at the end of the next section.
can you do?
offers only a beginning look at zoonotic diseases. For specific
information about any of the diseases or maintaining a safe
water supply, read the following publications available at any
sure drinking water is safe, Pm-1563g
your livestock and be safe, Pm-1265b
disease: A newly described illness in humans and animals,
2-c; 3-a; 4-c
Publication #: Pm-1563h
Fact Sheet is apart of
a series from the Safe Farm Program, Iowa State University Extension,
Ames, Iowa. Safe Farm promotes health and safety in agriculture.
It is funded by the National Institute for Occupational Safety
and Health (NIOSH #U05/CCU706051-03), Iowa State University,
and a network of groups that serve Iowa farm workers and their
families. Publication date: November 1994.
by Loren A. Will, extension veterinarian, and edited by Laura
Miller, extension communications, Iowa State University Extension,
Disclaimer and Reproduction Information: Information in
NASD does not represent NIOSH policy. Information included in
NASD appears by permission of the author and/or copyright holder.