Zoonoses - Colorado State University



Zoonoses: Disease from Animals to Humans

BACKGROUND

If you live in the front range area, you’re probably exposed to animals on a daily bases, whether working on a farm full of cattle herds and horses, pets at home, or even just walking through a park and seeing squirrels. Here are some warnings you should be aware of.

Zoonosis or Zoonoses (pl.) are any diseases caused by infectious agents that are transmitted from animals to humans. The infectious agents that cause Zoonotic diseases include bacteria, viruses, parasites, and fungi. Zoonotic diseases represent significant public health threats, but many of them can be avoided. In Larimer County, these include, but are not limited to: Plague, Rabies, Tularemia, West Nile Virus, Colorado Tick Fever, Hanta Virus, and Western Equine Encephalitis.

Zoonotic diseases have various ways of spreading, making them very hard to cure. Most Zoonotic diseases are transferred by direct contact with infected animals. For example, Tapeworms can often spread to humans when people eat the infected meat of cattle and swine. Other diseases are transferred by insect vectors which are often blood-feeding insects that carry the cause of the disease from one animal to another.

LIST OF AGENTS

Bacterial

• Plague (apply link)

• Tularemia (apply link)

• Lyme Disease (apply link)

Viral

• Rabies (apply link)

• Dengue Fever (apply link)

• Hanta Virus (apply link)

• West Nile Virus (apply link)

• Yellow Fever (apply link)

Parasitic (apply link)

Fungal (apply link)

CARRIERS

The following is a partial list of animals and the diseases that they may carry. Not all animal carriers are listed, nor are all the diseases that the various species can carry.

• Bats

o Commonly known to carry the virus that causes Rabies and also carry several other viral diseases that can affect humans.

• Cats

o Can carry the causative organisms for Plague, Anthrax, cowpox, Tapeworm, and many bacterial infections.

• Dogs

o May carry Plague, Tapeworms, Rabies, Rocky Mountain Spotted Fever, and Lyme disease.

• Horses

o Can carry Anthrax, Rabies, and Salmonella infections.

• Cattle

o May carry the organisms that cause Anthrax, European tick-borne encephalitis, Rabies, Tapeworm, Salmonella infections and many bacterial and viral diseases.

• Pigs

o Best known for carrying Tapeworm, but also carry a large number of other infections including Anthrax, Influenza, and Rabies.

• Sheep and goats

o May carry Rabies, European tick-borne encephalitis, Salmonella infections, and many bacterial and viral diseases.

• Rabbits

o May carry Plague and Q-Fever.

• Birds

o May carry Campylobacteriosis, Chlamydia psittaci, Pasteurella multocida, Histoplasma capsulatum, Salmonellosis, and others.

PLAGUE

What is the Plague?

You’ve probably heard of the “Black Plague” from your high school history class, but it’s actually part of a larger Zoonotic disease simply called the Plague. It is a bacterial disease of rodents that can spread to humans and other animals by infected fleas. There are three major forms of the disease:

• Bubonic Plague is an infection of the lymph nodes (Black Plague)

• Pneumonic Plague is an infection of the lungs

• Septicemic Plague is an infection of the blood

The organism Yersinia pestis causes Plague. Rodents, such as rats, spread the disease to humans.

How do people get the Plague?

People can get the Plague when a flea that carries the Plague bacteria from an infected rodent bites them. In rare cases, you may get the disease when handling an infected animal. Here are some ways to get Plague:

• By the bites of infected fleas

• By direct contact with the tissues or body fluids of a Plague-infected animal

• By inhaling infectious airborne droplets from persons or animals, especially cats, with Plague pneumonia

• By laboratory exposure to Plague bacteria

What are the signs and symptoms of the Plague?

Bubonic Plague symptoms appear suddenly, usually after 2-5 days of exposure to the bacteria. Symptoms include:

• High fever

• Smooth, painful lymph gland swelling called a buboe

o Commonly found in the groin, but may occur in the armpits or neck.

o Pain may occur in the area before the swelling.

• Chills

• General ill feeling (malaise)

• Muscle pain

• Severe headache

• Seizures

Pneumonic Plague symptoms appear suddenly, typically 2-3 days after exposure. They include:

• Severe cough

• Frothy, bloody sputum

• Difficulty breathing

Septicemic Plague may cause death even before the symptoms occur. Symptoms can include:

• Abdominal pain

• Blood clotting problems

• Diarrhea

• Fever

• Low blood pressure

• Nausea

• Organ failure

• Vomiting

What is the treatment for the Plague?

If diagnosed in time, Plague is treatable with antibiotics. Treatment of suspected Plague cases should start as soon as possible after the laboratory examinations of the specimen. Streptomycin is usually the antibiotic administered, but several other antibiotics are also effective.

How can the Plague be prevented?

• Do not feed any rodent or rabbit species in the wild.

• When camping or hiking, do not hang around in rodent-infested areas. Do not catch,

play with or attempt to hand feed wild rodents.

• Avoid contact with all sick and dead rodents and rabbits. Look for the

presence of blowflies or dead animal smell as evidence of animal die-offs.

• While hiking, treat pants, socks, shoe tops, arms and legs with insect

repellants.

• Insecticide powders or shampoos should be used on cats and dogs every few

days while in Plague areas.

• Cats sometimes exhibit swelling and sores around the mouth head and neck when infected. Seek professional veterinarian care for such animals and do not handle suspiciously sick pets without gloves and face protection.

• Remember the incubation period of 2-6 days and consult a physician if

sudden unexplained illness occurs within that period after activities in the

outdoors.

Where can I find more information about the Plague?

• CDC (Center for Disease and Control)

o

• WHO (World Health Organization)

o

• Larimer County – Home

o

TULAREMIA

What is Tularemia?

Tularemia is a bacterial disease associated with both animals and humans. Many wild and domestic animals can be infected. The rabbit is most often involved in disease outbreaks, which hints at its alternate name, rabbit fever.

Tularemia is caused by the bacterium Francisella tularensis. The primary vectors are ticks and deer flies although it can also spread through arthropods. The most known reservoir hosts include rabbits, prairie dogs, hares, and muskrats.

How do people get Tularemia?

People can get this disease mostly by being involved in outdoor activities. Some of the most common ways are:

• Bites from infected ticks

• Direct contact through the skin or mucous membranes with blood or tissue while handling infected animals (rabbit hunting)

• Contact with fluids from infected deer flies or ticks

• Handling or eating insufficiently cooked rabbit meat

• Drinking contaminated water

• Inhaling dust from contaminated soil or handling contaminated pets or wild animals

The good news about Tularemia is that it’s not spread from human to human.

What are the signs and symptoms of Tularemia?

Symptoms vary, depending on the route of introduction.

Cases of infection after handling an animal carcass:

• Slow-growing ulcer at the site where the bacteria entered the skin (usually on the hand)

• Swollen lymph nodes

Cases when the bacterium is inhaled:

• Pneumonia-like symptoms

o Severe cough

o Frothy, bloody sputum

o Difficulty breathing

Cases when the bacterium is ingested:

• Sore throat

• Abdominal Pain

• Diarrhea and Vomiting

What is the treatment for Tularemia?

Usual cases are treated with Steptomyocin, Gentamicin, Tetracyclin, Chloramphinicol, or Fluroquinolones.

How can Tularemia be prevented?

• Avoid drinking, bathing, swimming or working in untreated water where infection may be common among wild animals.

• Use impermeable gloves when skinning or handling animals, especially rabbits.

• Cook the meat of wild rabbits and rodents thoroughly.

• Avoid being bitten by deer flies and ticks. Here are a few helpful hints:

o Check your clothing often for ticks. Wear light-colored long-sleeved shirts and long pants so the tiny ticks are easier to see. Tuck long pants into your socks and boots. Wear a head covering or hat for added protection.

o For those who may not tolerate wearing all of these clothes in hot, humid weather, apply insect repellent containing DEET. Be sure to wash treated skin after coming indoors. If you do cover up, use repellents while in locations where ticks are common.

o Walk in the center of trails so weeds do not brush against you. Weeds serve good nesting locations for flies and ticks.

o Check yourself, children and other family members every two to three hours for ticks. Most ticks seldom attach quickly and rarely transmit tick-borne disease until they have been attached for four or more hours.

o If you let your pets outdoors, check them often for ticks. Infected ticks also can transmit some tick-borne diseases to them. (Check with your veterinarian about preventive measures against tick-borne diseases.) You are at risk from ticks that "hitch a ride" on your pets but fall off in your home before they feed.

o Make sure the property around your home is unattractive to ticks. Keep your grass mowed and keep weeds cut.

Where can I find more information about Tularemia?

• CDC (Center for Disease and Control)

o

• WHO (World Health Organization)

o

• Larimer County – Home

o

LYME DISEASE

What is Lyme Disease?

Lyme disease is a bacterial disease transmitted by infected ticks. In the U.S. it’s caused by the bacterium Borrelia afzelii.

How do people get Lyme Disease?

• By the bites of infected deer ticks (black-legged tick)

What are the signs and symptoms of Lyme Disease?

Symptoms vary greatly from one person to another. Symptoms also vary with the length of time a person has been infected.

• Ring-like red rash (grows larger over time)

o Rash usually accompanied by:

• Fatigue, chills and fever

• Headache

• Swollen lymph nodes

• Joint and muscle pain

What is the treatment for Lyme Disease?

Antibiotics are the primary treatment for Lyme disease. Usual cases are treated with Doxycycline, Amoxicillin and Ceftriaxone.

How can Lyme Disease be prevented?

The best way to protect yourself against Lyme disease and other tickborne illnesses is to avoid tick bites. This includes avoiding tick-infested areas. However, if you live in or visit wooded areas or areas with tall grass and weeds, follow these precautions against Lyme disease and other tickborne diseases like Rocky Mountain Spotted Fever and Tularemia.

• Avoid being bitten by deer flies and ticks. Here are a few helpful hints:

o Check your clothing often for ticks. Wear light-colored long-sleeved shirts and long pants so the tiny ticks are easier to see. Tuck long pants into your socks and boots. Wear a head covering or hat for added protection.

o For those who may not tolerate wearing all of these clothes in hot, humid weather, apply insect repellent containing DEET. Be sure to wash treated skin after coming indoors. If you do cover up, use repellents while in locations where ticks are common.

o Walk in the center of trails so weeds do not brush against you.

o Check yourself, children and other family members every two to three hours for ticks. Most ticks seldom attach quickly and rarely transmit tick-borne disease until they have been attached for four or more hours.

o If you let your pets outdoors, check them often for ticks. Infected ticks also can transmit some tick-borne diseases to them. (Check with your veterinarian about preventive measures against tick-borne diseases.) You are at risk from ticks that "hitch a ride" on your pets but fall off in your home before they feed.

o Make sure the property around your home is unattractive to ticks. Keep your grass mowed and keep weeds cut.

Where can I find more information about Lyme Disease?

• CDC (Center for Disease and Control)

o

• WHO (World Health Organization)

o

• Larimer County – Home

o

RABIES

What is Rabies?

Do you ever wonder why you can’t have squirrels or other really cute looking wild rodents as pets? One of the answers is Rabies. Rabies is a viral infection that affects the nervous system. This Zoonotic disease is known for causing acute encephalitis (inflammation of the brain) in mammals. It is caused by the RNA virus, Lyssavirus , most commonly referred to as the Rabies Virus.

How do people get Rabies?

People get Rabies from infected mammals, most commonly bats. Rabies is transmitted most often through animal bites, although other contact with the saliva or brain tissue of an infected animal can cause the disease. It can also be spread by an unnoticeable bite from a bat with Rabies, even without an obvious wound. There have currently been a few isolated cases of Rabies infection through skunk interactions in Colorado.

What are the signs and symptoms of Rabies?

The Rabies virus travels through the nervous system, eventually inflaming the brain. Early symptoms include:

• Irritability

• Headache

• Fever

• Itching or pain at the site of the bite

The disease progresses if untreated and is accompanied by the following signs:

• Paralysis

• Spasms of the throat muscles

• Convulsions

• Delirium

What is the treatment for Rabies?

As soon as a bite has been identified, it’s important to clean the wounded area to avoid infection. A series of vaccinations after exposure can prevent the disease from worsening and spreading. Once symptoms appear, treatment is highly unlikely to be found and often leads to fatality.

How can Rabies be prevented?

• Do not feed, touch or adopt wild animals or stray dogs or cats.

• Vaccinated pets serve as a buffer between rabid wildlife and humans, so be sure dogs and cats are up-to-date on their Rabies vaccinations. Consult with your veterinarian about when your pet needs to be vaccinated.

• Do not allow pets to roam free.

• Do not attract wild animals to your home or yard. Store bird seed or other animal feed in containers with tight-fitting lids. Feed pets indoors. Make sure garbage cans are tightly capped. Board up any openings to your attic, basement, porch or garage. Cap chimneys with screens.

• Encourage children to immediately tell an adult if they are bitten or scratched by an animal. Teach children not to approach or to touch any animal they do not know.

• Report all animal bites to the local animal control.

• AGAIN, MAKE SURE ALL PETS ARE VACCINATED.

Where can I find more information about Rabies?

• CDC (Center for Disease and Control)

o

• WHO (World Health Organization)

o

• Larimer County – Home

o

DENGUE FEVER

What is Dengue Fever?

Dengue Fever is a viral disease spread by the bite of infected mosquitoes. Its more sever and often fatal form is called Dengue Hemorrhagic Fever. Dengue and Dengue Hemorrhagic Fever are caused by any of the Dengue family of viruses, Flaviviridae. Infection with one virus does not protect a person against infection with another.

How do people get Dengue Fever?

Dengue is spread by the bite of an Aedes mosquito containing the Dengue virus. The mosquito transmits the disease by biting an infected person and then biting someone else.

According to Medical News Today, Dengue fever is the most common insect-borne virus infection, causing more than 50 million infections, 500,000 cases of dengue hemorrhagic fever and at least 12000 deaths per year.

What are the signs and symptoms of Dengue Fever?

Early symptoms include:

• High fever

• Rash

• Severe headache

• Pain behind the eyes

• Muscle and joint pain

More sever signs include:

• Nausea

• Vomiting

• Loss of an appetite

• Dengue Hemorrhagic Fever symptoms:

o Bleeding from the nose, mouth, and gums

What is the treatment for Dengue Fever?

There is no specific treatment for Dengue. Persons with Dengue fever should rest and drink plenty of fluids. They should be kept away from mosquitoes for the protection of others. Dengue Hemorrhagic Fever is treated by replacing lost fluids. Blood transfusions to control bleeding may be required for severe hemorrhagic symptoms.

How can Dengue Fever be prevented?

There is no commercially available vaccine for the Dengue virus. Avoid mosquito bites by the following:

• Use mosquito repellents on skin and clothing.

• When outdoors during times that mosquitoes are biting, wear long-sleeved shirts and long pants tucked into socks.

• Avoid heavily populated residential areas, as this increases the chance of transmission from person to person.

• When indoors, stay in air-conditioned or screened areas. Use bed nets if sleeping areas are not screened or air-conditioned.

Eliminate mosquito breeding sites in areas where Dengue might occur:

• Eliminate mosquito breeding sites around homes. Discard items that can collect rain or run-off water, especially old tires.

• Regularly change the water in outdoor bird baths and pet and animal water containers.

Where can I find more information about Dengue Fever?

• CDC (Center for Disease and Control)

o

• WHO (World Health Organization)

o

• Larimer County – Home

o

WEST NILE VIRUS

What is West Nile?

If you live in or around Colorado, you’ve probably heard of West Nile, but did you know that the Rocky Mountain region is the most common area for this Zoonotic disease? In fact, West Nile was seen in Colorado in 2003 and there have been many reported and unreported cases. West Nile without question is here to stay.

West Nile is a virus of the family Flaviviridae that spreads by the bite of infected mosquitoes.

How do people get West Nile?

People get West Nile disease from the bite of the Culex mosquito that is infected with West Nile virus. A mosquito becomes infected by biting a bird that carries the virus. West Nile virus is not spread by person-to-person contact or directly from birds to people.

What are the signs and symptoms of West Nile?

Most people who are infected experience mild signs such as fever and headache. More sever signs include (usually elderly individuals) West Nile encephalitis (inflammation of the brain).

What is the treatment for West Nile?

There is no specific therapy for West Nile disease. In more severe cases, intensive supportive therapy (hospitalization, intravenous (IV) fluids, airway management, respiratory support such as ventilators are used). Prevention of secondary infections (pneumonia, urinary tract, etc.) is also optional.

How can West Nile be prevented?

The best way to prevent West Nile disease or any other mosquito-borne illness is to reduce the number of mosquitoes around your home and neighborhood and to take personal precautions to avoid mosquito bites. Here are some suggestions:

• Avoid being outdoors when mosquitoes are most active, especially between dusk and dawn.

• When outdoors, wear shoes and socks, long pants and a long-sleeved shirt, and apply insect repellent that Includes DEET, picaridin or oil of lemon eucalyptus according to label instructions. Consult a physician before using repellents on infants.

• Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or other openings. Try to keep doors and windows shut, especially at night.

• Eliminate all sources of standing water that can support mosquito breeding, including water in bird baths, ponds, flowerpots, wading pools, old tires and any other receptacles. In communities where there are organized mosquito control programs, contact your municipal government to report areas of stagnant water in roadside ditches, flooded yards and similar locations that may produce mosquitoes.

Where can I find more information about West Nile?

• CDC (Center for Disease and Control)

o

• WHO (World Health Organization)

o

• Larimer County – Home

o

The following are Zoonotic diseases not commonly found in the U.S. Humans are usually infected through traveling to different continents where this disease is prevalent.

YELLOW FEVER

What is Yellow Fever?

You’ve probably never thought of fever to have a color, so what’s Yellow Fever you ask? Yellow Fever is a tropical disease that is usually found in South America and Africa.

How do people get Yellow Fever?

People get Yellow Fever from the bite a mosquito that is infected with the Flaviviridae family of viruses, more specifically the Yellow Fever virus.

What are the signs and symptoms of Yellow Fever?

Many Yellow Fever infections are mild, but the disease can cause severe, life-threatening illness. Symptoms of severe infection are:

• High fever and chills

• Headache

• Muscle aches

• Vomiting

• Backache

After a brief recovery period, the infection can lead to:

• Shock

• Bleeding

• Kidney and liver failure

Liver failure causes jaundice (yellowing of the skin and the whites of the eyes), which gives Yellow Fever its name.

What is the treatment for Yellow Fever?

There is no specific treatment for Yellow Fever. Persons with Yellow Fever should rest and drink plenty of fluids. They should be kept away from mosquitoes for the protection of others. Individuals with a healthy lifestyle and a good immune system usually get better after a long recovery period.

How can Yellow Fever be prevented?

Yellow Fever can be prevented by vaccination. Travelers should also take precautions against mosquito bites when in areas with Yellow Fever transmission.

If necessary, get vaccinated for Yellow Fever before travel.

Travelers should get vaccinated for Yellow Fever before visiting areas where Yellow Fever is found. In the United States, the vaccine is given only at designated Yellow Fever vaccination centers. International regulations require proof of Yellow Fever vaccination for travel to and from certain countries. People who get vaccinated should be given an International Certificate of Vaccination.

Avoid mosquito bites when traveling in tropical areas.

Mosquitoes that spread Yellow Fever usually bite during the day. Travelers should take steps to reduce contact with mosquitoes when outdoors and inside.

When outside:

• Wear long-sleeved clothing and long pants. For extra protection, treat clothing with the insecticide permethrin.

• Use insect repellent on exposed skin. The most effective repellents contain 20% to 35% DEET (N,N-diethylmethyltoluamide). Follow application instructions carefully when using these products.

When inside:

• Stay in well-screened areas as much as possible.

• Spray living and sleeping areas with insecticide.

• Use a bed net when sleeping in a room that is not screened or air conditioned. For extra protection, treat the bed net with the insecticide Permethrin.

Where can I find more information about Yellow Fever?

• CDC (Center for Disease and Control)

o

• WHO (World Health Organization)

o

• Larimer County – Home

o

• International Travel Immunization Clinic

o

PARASITIC

Parasites range in size from tiny, one-celled organisms called protozoa to worms that can be seen with the naked eye. Some parasitic diseases happen in the United States. Contaminated water supplies can lead to Giardia infections caused by a parasite called Giardia intestinalis which lives in soil, food and water. Cats can transmit Toxoplasmosis, which are dangerous in pregnant women. Others, like Malaria, are common in different parts of the world like Africa, India and Asia.

If you are traveling, it's important to drink only water you know is safe. Prevention is especially important. There are no vaccines for parasitic diseases. Some medicines are available to treat parasitic infections and to treat the symptoms themselves.

FUNGAL

If you have ever had athlete's foot or a yeast infection, you can blame a fungus. A fungus is actually a primitive vegetable. Mushrooms, mold and mildew are examples. Fungi live in air, in soil, on plants and in water. Some live in the human body. Only about half of all types of fungi are harmful.

Some fungi reproduce through tiny spores in the air. You can inhale the spores or they can land on you. As a result, fungal infections often start in the lungs or on the skin. You are more likely to get a fungal infection if you have a weakened immune system or take antibiotics.

Fungi are very hard to kill. For skin and nail infections, you can apply medicine directly to the infected area. Oral antifungal medicines are also available for serious infections.

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