ZOONOSIS: (zo"o-no'sis) pl. zoono'ses - a disease of animals that may be transmitted to man under natural conditions (e.g., brucellosis, rabies).
What Are Some Examples Of Zoonotic Diseases?
Zoonotic disease has a long history. Ancient Greece and the Bible mention the Plague. The number of potential zoonotic diseases 'out there' today is impressive. We hear about Rabies, Ringworm, and Lyme disease, but many other diseases pose a threat to humans.
* Plague Rodents, cats, rabbits, squirrels, related animals. A bacteria transmitted by fleas, aerosols, handling infected animals.
Plague :
* Plague is a bacterial disease of rodents that can be spread to humans and other animals by infected fleas.
* Plague has three forms: bubonic plague (infection of the lymph glands), septicemia plague (infection of the blood), and pneumonic plague (infection of the lungs). Pneumonic plague can spread from person to person.
* People can 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 with plague pneumonia; or by laboratory exposure to plague bacteria.
* Plague is treatable with antibiotics if detected early.
* Prevention consists of controlling rodent fleas, educating the public and the medical community in places where plague occurs, and using preventive medicines and vaccines as appropriate.
What is plague?
Plague is a disease of rodents that can be spread to humans another animals by infected fleas. In people, plague has three forms: Bubonic plague, infection of the lymph glands; septicemia plague, infection of the blood; and pneumonic plague, infection of the lungs. Pneumonic plague is the most contagious form because it can spread from person to person in airborne droplets.
What is the infectious agent that causes plague?
Perinea pests cause plague, a bacterium that is spread from rodent to rodent by infected fleas. Periodic outbreaks of plague kill large numbers of rodents (called a "die-off"). The risk of infection to humans and other animals in the area increases when the rodent hosts die and infected fleas look for other sources oxblood.
Where is plague found?
Plague is found in some semi-arid areas in Asia, Eastern Europe, Africa, South America, and North America. In the United States, most cases in humans occur in two regions: 1) northern New Mexico, northern Arizona, and southern Colorado, and 2) southern Oregon, and far western Nevada.
In the southwestern United States, rock squirrel fleas are the most common source of infection in people. In the Pacific states, Many other types of rodents -- including other ground squirrels, prairie dogs, chipmunks, wood rats, wild mice, and voles -- suffer plague outbreaks and are occasional sources of human infection. Domesticates can be infected by fleas or by eating infected wild rodents and can be a direct source of infection to people. Dogs rarely suffer severe illness and have yet to be shown to be sources of infection for humans.
How do people 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 plague?
When a person is bitten by an infected flea or is infected by handling an infected animal, the plague bacteria move through the bloodstream to the lymph nodes. The lymph nodes swell, causing the painful lumps ("buboes") that are characteristic of bubonic plague. Other symptoms are fever, headache, chills, and extreme tiredness. Some people have gastrointestinal symptoms.
If bubonic plague goes untreated, the bacteria can multiply in the bloodstream and produce plague septicemia (septicemia plague), severe blood infection. Signs and symptoms are fever, chills, tiredness, abdominal pain, shock, and bleeding into the skin another organs. Untreated septicemia plague is usually fatal.
Pneumonic plague, or plague pneumonia, develops when the bacteria infect the lungs. People with plague pneumonia have high fever, chills, difficulty breathing, a cough, and bloody sputum. Plague pneumonia is considered a public health emergency because a cough can quickly spread the disease to others. Untreated pneumonic plague is usually fatal.
How soon after exposure do symptoms appear?
Symptoms usually begin within 2 to 6 days after exposure to the plague bacteria.
How is plague diagnosed?
U.S. health-care providers should suspect plague in anyone with large, painful, very tender lymph gland accompanied by fever, extreme tiredness, and a history of exposure to possibly infected rodents and their fleas in the western United States. Plague should also be suspected in a person with plague symptoms plus a history of handling sick or dead cats, or wild animals such as rabbits.
Patients with suspected plague should be hospitalized, placed in isolation, have specimens obtained for plague diagnosis, and immediately treated. All suspected plague cases must also be reported to local and state health departments.
What is the treatment for plague?
If diagnosed in time, plague is treatable with antibiotics. Treatment of suspected plague cases should start as soon as possible after the laboratory specimens are taken. The drug of choice is streptomycin, but several other antibiotics are also effective.
How common is plague?
In the United States, human plague cases average about 10 to 15per year. Worldwide, there are 1,000 to 2,000 cases each year.
Who is at risk for plague?
* People who live in rural areas where plague occurs in wild rodents
* People, such as biologists, trappers, and hunters, who handle potentially infected animals
* Campers, hikers, travelers, and others in areas where plague is known to exist
* People in close contact with pneumonic plague patients
Is plague a new or emerging infectious disease?
Plague is an ancient disease that occurs in irregular cycles and remains a public health hazard in parts of Asia, the Middle East, Eastern Europe, Africa, and South America, as well as the United States. Epidemics of plague in humans usually involve house rats and their fleas. Rat-borne epidemics continue to occur in some developing countries, particularly in rural areas. Highly publicized outbreaks of bubonic and pneumonic plague occurred in 1994 in India, leading toad heightened international reaction. The last rat-borne epidemic in the United States occurred in Los Angeles in 1924-1925. Since then, all human plague cases in the United States have been associated with plague outbreaks in wild rodents and their fleas.
How can plague be prevented?
1. People who live, work, or play in areas with active plague infection in wild rodents should take these precautions:
* Eliminate food and shelter for rodents around homes, work places, and certain recreation areas, such as picnic sites or campgrounds where people congregate. Remove brush, rock piles, junk, and food sources, including pet food.
* Allow health authorities to use appropriate and licensed insecticides to kill fleas during plague outbreaks in wild animals.
* Treat pets (cats and dogs) for flea control regularly.
* Avoid sick or dead animals, and report such animals to the health department. Hunters and trappers should wear rubber gloves when skinning animals.
* Use insect repellents when outdoors in areas where there is a risk of flea exposure.
2. Preventive treatment with antibiotics is recommended for:
1) people who are bitten by fleas during a local outbreak or who are exposed to tissues or fluids from a plague-infected animal;
2) people living in a household with a bubonic plague patient, since they may also be exposed to infected fleas; and
3) people in close contact with a person or pet with suspected plague pneumonia. Close contacts defined as face-to-face contact or being in the same closed space, such as a room or vehicle.
3. People who travel to countries where plague occurs should take these additional precautions:
* Avoid exposure to fleas from diseased rats. The risk of being bitten by infected fleas is especially high after large numbers of plague-infected rats have died. Therefore, avoid places that are infested with rats or where large numbers of rats have reportedly died.
* If travel to such areas is essential, apply insect repellent containing DEET to legs and ankles. Also apply repellents and insecticides to clothes and outer bedding according to manufacturers' instructions.
* Take preventive antibiotics if the risk of exposure is high.
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* Tuberculosis Caused by a bacterium called Mycobacterium tuberculosis.
Where did TB come from?
Mycobacteria are Gram-resistant (waxy cell walls), non-motile, pleomorphic rods, related to the Actinomyces. Most Mycobacteria are found in habitats such as water or soil. However, a few are intracellular pathogens of animals and humans. Mycobacterium tuberculosis, along with M. bovis, M. africanum, and M. microti all cause the disease known as tuberculosis (TB) and are members of the tuberculosis species complex. Each member of the TB complex is pathogenic, but M. tuberculosis is pathogenic for humans while M. bovis is usually pathogenic for animals.
M. bovis was causing TB in the animal kingdom long before invading humans. However, after the domestication of cattle between 8000-4000 BC, there is archaeological evidence of human infection by M. bovis probably through milk consumption. M. tuberculosis is probably a human-specialized form of M. bovis developed among milk-drinking Indo-Europeans who then spread the disease during their migration into western Europe and Eurasia. By 1000 BC, M. tuberculosis and pulmonary TB had spread throughout the known world.
Tuberculosis complex organisms are:
* Obligate aerobes growing most successfully in tissues with a high oxygen content, such as the lungs.
* Facultative intracellular pathogens usually infecting mononuclear phagocytes (e.g. macrophages).
* Slow-growing with a generation time of 12 to 18 hours (c.f. 20-30 minutes for Escherichia coli).
* Hydrophobic with a high lipid content in the cell wall. Because the cells are hydrophobic and tend to clump together, they are impermeable to the usual stains, e.g. Gram's stain.
* Known as "acid-fast bacilli" because of their lipid-rich cell walls, which are relatively impermeable to various basic dyes unless the dyes are combined with phenol. Once stained, the cells resist decolorization with acidified organic solvents and are therefore called "acid-fast". (Other bacteria which also contain mycolic acids, such as Nocardia, can also exhibit this feature.)
The video shows M. tuberculosis cells subjected to the Ziehl-Neelsen acid-fast staining procedure, a commonly used diagnostic method for Mycobacteria:
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* Cat Scratch Fever Caused by a bacterium called Bartonella henselae.
Cat scratch disease (CSD) is a bacterial disease caused by Bartonella henselae. Most people with CSD have been bitten or scratched by a cat and developed a mild infection at the point of injury. Lymph nodes, especially those around the head, neck, and upper limbs, become swollen. Additionally, a person with CSD may experience fever, headache, fatigue, and a poor appetite. Rare complications of B. henselae infection are bacillary angiomatosis and Parinaud's oculolandular syndrome.
Can my cat transmit Bartonella henselae to me?
Sometimes, yes, cats can spread B. henselae to people. Most people get CSD from cat bites and scratches. Kittens are more likely to be infected and to pass the bacterium to people. About 40% of cats carry B. henselae at some time in their lives. Cats that carry B. henselae do not show any signs of illness; therefore, you cannot tell which cats can spread the disease to you. People with immunocompromised conditions, such as those undergoing immunosuppressive treatments for cancer, organ transplant patients, and people with HIV/AIDS, are more likely than others to have complications of CSD. Although B. henselae has been found in fleas, so far there is no evidence that a bite from an infected flea can give you CSD.
How can I reduce my risk of getting cat scratch disease from my cat?
* Avoid "rough play" with cats, especially kittens. This includes any activity that may lead to cat scratches and bites.
* Wash cat bites and scratches immediately and thoroughly with running water and soap.
* Do not allow cats to lick open wounds that you may have.
* Control fleas.
* If you develop an infection (with pus and pronounced swelling) where you were scratched or bitten by a cat or develop symptoms, including fever, headache, swollen lymph nodes, and fatigue, contact your physician.
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* Hantavirus :
Hantavirus pulmonary syndrome (HPS) is a deadly disease from rodents. Humans can contract the disease when they come into contact with infected rodents or their urine and droppings. HPS was first recognized in 1993 and has since been identified throughout the United States. Although rare, HPS is potentially deadly. Rodent control in and around the home remains the primary strategy for preventing hantavirus infection.
What is hantavirus pulmonary syndrome (HPS)?
Hantavirus pulmonary syndrome (HPS) is a deadly disease caused by hantaviruses. Rodents can transmit hantaviruses through urine, droppings, or saliva. Humans can contract the disease when they breathe in aerosolized virus.
Who is at risk of contracting HPS?
Anyone who comes into contact with rodents that carry hantavirus is at risk of HPS. Rodent infestation in and around the home remains the primary risk for hantavirus exposure. Even healthy individuals are at risk for HPS infection if exposed to the virus.
Which rodents are known to be carriers of hantavirus that cause HPS in humans?
In the United States, deer mice, cotton and rice rats (in the Southeast), and the white-footed mouse (in the Northeast), are the only known rodent carriers of hantaviruses causing HPS.
How is HPS transmitted?
Hantavirus is transmitted by infected rodents through urine, droppings, or saliva. Individuals become infected with HPS after breathing fresh aerosolized urine, droppings, saliva, or nesting materials. Transmission can also occur when these materials are directly introduced into broken skin, the nose or the mouth. If a rodent with the virus bites someone, the virus may be spread to that person, but this type of transmission is rare.
Can you contract HPS from another person?
HPS in the United States cannot be transmitted from one person to another. You cannot get the virus from touching or kissing a person who has HPS or from a health care worker who has treated someone with the disease. In addition, you cannot contract the virus from a blood transfusion in which you receive blood from a person who survived HPS.
Can you contract HPS from other animals?
Hantaviruses that cause HPS in the United States are only known to be transmitted by certain species of rodents. HPS in the United States is not known to be transmitted by farm animals, dogs, or cats or from rodents purchased from a pet store.
How long can hantavirus remain infectious in the environment?
The length of time hantaviruses can remain infectious in the environment is variable and depends on environmental conditions, such as temperature and humidity, whether the virus is indoors or outdoors or exposed to the sun, and even on the rodent’s diet (which would affect the chemistry of its urine). Viability for 2 or 3 days has been shown at normal room temperature. Exposure to sunlight will decrease the time of viability, and freezing temperatures will actually increase the time that the virus remains viable. Since the survival of infectious virus is measured in terms of hours or days, only active infestations of infected rodents result in conditions that are likely to lead to human hantavirus infection.
How do I prevent HPS?
SEAL UP, TRAP UP, CLEAN UP
Seal up rodent entry holes or gaps with steel wool, lath metal, or caulk. Trap rats and mice by using an appropriate snap trap. Clean up rodent food sources and nesting sites and take precautions when cleaning rodent-infested areas. See the HPS Prevention Checklist for a complete listing.
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* Tick Paralysis Various animals affected. Requires the tick to be attached to the human - venom is released by the tick. This disease is classified under a broader definition of zoonotic dieases. For more info, please see the AVMA Tick Paralysis Q & A by A. Alan Kocan, PhD.
What is Tick Paralysis?
Tick Paralysis is caused by over 40 species of ticks worldwide (five in North America, including the deer tick) and can occur in almost any region where ticks are found. It has killed thousands of animals, mainly cows and sheep, in other parts of the world. Although tick paralysis is of concern in domestic animals and livestock in the United States as well, human cases are rare and usually occur in children under the age of 10.
Tick paralysis occurs when an engorged and gravid (egg-laden) female tick produces a neurotoxin in its salivary glands and transmits it to its host during feeding. Experiments have indicated that the greatest amount of toxin is produced between the fifth and seventh day of attachment (often initiating or increasing the severity of symptoms), although the timing may vary depending on the species of tick.
Unlike Lyme disease, ehrlichiosis, and babesiosis, which are caused by the systemic proliferation and expansion of parasites in their hosts long after the offending tick is gone, tick paralysis is chemically induced by the tick and can therefore continue only in its presence. Once the tick is removed, symptoms usually diminish rapidly. However, in some cases, profound paralysis can develop and even become fatal before anyone becomes aware of a tick's presence.
Where is Tick Paralysis Prevalent?
Ticks that cause tick paralysis are found in almost every region of the world. In the United States, most reported cases have occurred in the Rocky Mountain states, the Pacific Northwest and parts of the South. The five North American species of ticks thought to cause tick paralysis are widely distributed throughout the United States; therefore, the potential for contact with such ticks exists in every state.
Symptoms
Symptoms of tick paralysis generally begin from five to seven days after a tick becomes attached (usually on the scalp), beginning with fatigue, numbness of the legs and muscle pains. Paralysis rapidly develops from the lower to the upper extremities and, if the tick is not removed, is followed by tongue and facial paralysis. The most severe complications may include convulsions, respiratory failure and, in up to 12% of untreated cases, death.
Diagnosis
Because of the inability of laboratory tests to indicate tick paralysis, diagnosis is based on symptoms and the rapid improvement of the patient once the engorged tick is removed.
Treatment
Treatment involves simply removing the feeding tick(s). It is important to remove all the mouthparts, since they contain the salivary glands which may continue to infect the patient even after the body of the tick has been removed.
To remove an imbedded tick
Prevention & Control
As with all other tick-borne diseases, the most effective precautions against tick paralysis are to avoid walking through or brushing against vegetation and to perform daily self-examinations for ticks - even in the fall and winter months.
If you live in regions with higher incidences of tick paralysis (see Where is Tick Paralysis Prevalent? above) and spend a lot of time outdoors, wearing long pants, long-sleeved shirts, socks and enclosed shoes may reduce a tick's chances of contacting your skin. Insect repellents containing the active ingredient DEET can be applied to the skin (be sure to strictly follow the manufacturer's directions) or to the clothes, while Permethrin can only be used on clothing. Hikers should stay on cleared, well-worn trails to avoid contact with vegetation.
Most importantly, no matter where you live, inspect yourself thoroughly after returning from any outing, even if you go no further than the front lawn. Prompt removal of ticks, preferably before they've had a chance to become engorged, will go a long way in preventing tick paralysis and other tick-borne diseases.
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Who Is At Risk For Zoonotic Disease?
Any human in contact with an infected animal or disease vector. A vector is a disease carrier that spreads the disease from an infected animal to an uninfected human or animal (i.e. insect, rodent, etc.) Some humans are more at risk than others:
* infants and small children - immature immune systems, poor hygiene - hands in mouth, etc.
* pregnant women - immune systems are more susceptible and there are additional fetal hazards
* elderly - immune systems may be impaired
* immunocompromised people - undergoing cancer therapy, HIV/AIDS patients, etc.
* veterinarians, zoo/wildlife/primate and other animal health care workers.
Where Can I Find More Information On Zoonotic Diseases?
Veterinarian
Your pet's Veterinarian is a good first source for information. Find out about the disease and most importantly, how to care for your animal and prevent spread to humans. Most Veterinarians have professional brochures and handout information on the common zoonotic diseases for your area