tularemia

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Tularemia

 

Definition

Tularemia is an illness caused by a bacterium. It results in fever, rash, and greatly enlarged lymph nodes.

Description

Tularemia infects a variety of wild animals, including rabbits, deer, squirrels, muskrat, and beaver. Humans can acquire the bacterium directly from contact with the blood or body fluids of these animals, from the bite of a tick or fly which has previously fed on the blood of an infected animal, or from contaminated food or water.
Tularemia occurs most often in the summer months. It is most likely to infect people who come into contact with infected animals, including hunters, furriers, butchers, laboratory workers, game wardens, and veterinarians. In the United States, the vast majority of cases of tularemia occur in the southeastern and Rocky Mountain states.

Causes and symptoms

Five types of illness may occur, depending on where/how the bacteria enter the body:
  • Ulceroglandular/glandular tularemia. Seventy-five to 85% of all cases are of this type. This type is contracted through the bite of an infected tick that has defecated bacteria-laden feces in the area of the bite wound. A tender red bump appears in the area of the original wound. Over a few weeks, the bump develops a punched-out center (ulcer). Nearby lymph nodes grow hugely swollen and very tender. The lymph nodes may drain a thick, pus-like material. Other symptoms include fever, chills, and weakness. In adults, the lymph nodes in the groin are most commonly affected; in children, the lymph nodes in the neck.
  • Oculoglandular tularemia. This type accounts for only about 1% of all cases of tularemia. It occurs when a person's contaminated hand rubs his or her eye. The lining of the eyelids and the surface of the white of the eye (conjunctiva) becomes red and severely painful, with multiple small yellow bumps and pitted sores (ulcers). Lymph nodes around the ears, under the jaw, or in the neck may swell and become painful.
  • Oropharyngeal and gastrointestinal tularemia. This type occurs when contaminated meat is undercooked and then eaten, or when water from a contaminated source is drunk. Poor hygiene after skinning and cleaning an animal obtained through hunting can also lead to the bacteria entering through the mouth. Sores in the mouth and throat, as well as abdominal pain, nausea and vomiting, ulcers in the intestine, intestinal bleeding, and diarrhea may all occur.
  • Pulmonary tularemia. This rare type of tularemia occurs when a person inhales a spray of infected fluid, or when the bacteria reach the lungs through the blood circulation. A severe pneumonia follows.
  • Typhoidal tularemia. This type of tularemia is particularly hard to diagnose, because it occurs without the usual skin manifestations or swelling of lymph glands. Symptoms include continuously high fever, terrible headache, and confusion. The illness may result in a severely low blood pressure, with signs of poor blood flow to the major organs (shock).

Diagnosis

Samples from the skin lesions can be prepared with special stains, to allow identification of the causative bacteria under the microscope. Other tests are available to demonstrate the presence of antibodies (special immune cells that the body produces in response to the presence of specific foreign invaders) which would be increasing over time in an infection with tularemia.

Treatment

Streptomycin (given as a shot in a muscle) and gentamicin (given as either a shot in a muscle or through a needle in the vein) are both used to treat tularemia. Other types of antibiotics have been tested, but have often resulted in relatively high rates of relapse (20%).

Prognosis

With treatment, death rates from tularemia are under 1%. Without treatment, however, the death rate may reach 30%. The pneumonia and typhoidal types have the worst prognosis without treatment.

Prevention

Prevention involves avoiding areas known to harbor ticks and flies, or the appropriate use of insect repellents. Hunters should wear gloves when skinning animals or preparing meat. Others (butchers, game wardens, veterinarians) who work with animals or carcasses should always wear gloves. A vaccine exists, but is usually only given to people at very high risk due to their profession or hobby (veterinarians, laboratory workers, butchers, hunters, game wardens).

Resources

Organizations

Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. (800) 311-3435, (404) 639-3311. http://www.cdc.gov.

Key terms

Conjunctiva — The lining of the eyelids and the surface of the white part of the eye.
Shock — A state in which drastically low blood pressure prevents adequate blood flow to the tissues and organs throughout the body.

tularemia

 [too″lah-re´me-ah]
a plaguelike disease of rodents, caused by Francisella tularensis, which is transmissible to humans. It can be contracted by handling diseased animals or their hides, eating infected wild game, or being bitten by insects such as horseflies or deer flies that have fed on such animals.

Symptoms and Treatment. Tularemia begins with a sudden onset of chills and fever, accompanied by headache, nausea, vomiting, and severe weakness. A day or so later, a small sore usually develops at the site of the infection, and it becomes ulcerated. There may also be enlargement and ulceration of the lymph nodes and a generalized red rash. In untreated cases, the fever may last for weeks or months. Treatment is with antibiotics, such as tetracycline, streptomycin, and chloramphenicol.
Prevention. Tularemia is usually thought of as an occupational disease. Those who may be exposed to it, such as game wardens and hunters, should take precautions such as wearing gloves when handling wild animals, particularly rabbits and squirrels, and wearing adequate clothing in the woods to prevent bites by insect vectors of the disease. Wild game must be especially well cooked in order to kill the tularemia organism.

tu·la·re·mi·a

(tū'lă-rē'mē-ă),
A disease caused by Francisella tularensis and transmitted to humans from rodents through the bite of a deer fly, Chrysops discalis, and other bloodsucking insects; can also be acquired directly through the bite of an infected animal or through handling of an infected animal carcass; symptoms, similar to those of undulant fever and plague, are a prolonged intermittent or remittent fever and often swelling and suppuration of the lymph nodes draining the site of infection; rabbits are an important reservoir host.
[Tulare, Lake and County, CA, + G. haima, blood]

tularemia

/tu·la·re·mia/ (too″lah-re´me-ah) a plaguelike disease of rodents, caused by Francisella tularensis and transmissible to humans.
oculoglandular tularemia  that in which the primary site of infection is the conjunctival sac, with conjunctivitis, corneal lesions, and enlargement of preauricular lymph nodes.
pulmonary tularemia , pulmonic tularemia that with involvement of the lungs by spread of primary infection or inhalation of the pathogen, with cough, fever, chest pain, and bloody sputum.
typhoidal tularemia  the most serious type, caused by swallowing the pathogen; symptoms are similar to those of typhoid.
ulceroglandular tularemia  the most common type in humans, beginning with a painful red papule at the point of inoculation, later forming a shallow ulcer; lymphadenopathy, hepatosplenomegaly, and pneumonia may also occur.

tularemia

(to͞o′lə-rē′mē-ə, tyo͞o′-)
n.
An infectious disease caused by the bacterium Francisella tularensis that chiefly affects rodents but can also be transmitted to humans through the bite of various insects or contact with infected animals. In humans, the disease is characterized by intermittent fever and swelling of the lymph nodes. Also called rabbit fever.

tu′la·re′mic adj.

tularemia

[to̅o̅′lərē′mē·ə]
Etymology: Tulare, California; Gk, haima, blood
an infectious disease of animals caused by the bacillus Francisella (Pasteurella) tularensis, which may be transmitted by insect vectors or direct contact. It is characterized in humans by fever, headache, and an ulcerated skin lesion with localized lymph node enlargement or by eye infection, GI ulcerations, or pneumonia, depending on the site of entry and the response of the host. This disease can be fatal if not treated with the appropriate antibiotics. Treatment includes streptomycin, chloramphenicol, and tetracycline. Recovery produces lifelong immunity. A vaccine was used in the past to protect laboratory workers but is not currently available; however, a new vaccine is in development. Also called deerfly fever, rabbit fever. Also spelled tularaemia.
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Tularemia

tularemia

Deerfly fever, rabbit fever Infectious disease An infection of wild small animals–eg, rabbits and rats caused by Francisella tularensis, a small, gram-negative aerobic bacillus, transmitted to man by bites or via arthropod vectors–eg, ticks, tabanids Clinical forms Oculoglandular, pneumonic–atypical pneumonia, typhoidal, ulceroglandular

tu·la·re·mi·a

(tū'lă-rē'mē-ă)
A disease caused by Francisella tularensis transmitted to humans from rodents through the bite of a deer fly, Chrysops discalis, and other bloodsucking insects; can also be acquired directly through the bite of an infected animal or through handling of an infected animal's carcass; symptoms consist of fever and swelling and suppuration of the lymph nodes draining the site of infection; rabbits are an important reservoir host.
Synonym(s): deerfly fever, rabbit fever, tularaemia.
[Tulare, Lake and County, CA, + G. haima, blood]

Ohara,

Shoichiro, 20th century Japanese physician.
Ohara disease - Synonym(s): tularemia

Tulare,

county in California where the disease was first discovered.
tularemia - a disease that is transmitted to humans from rodents through the bite of a deer fly or other bloodsucking insects, or through the handling of an infected animal carcass. Synonym(s): deer-fly disease; deer-fly fever; Pahvant Valley fever; Pahvant Valley plague; rabbit fever

tularemia

a highly contagious disease of rodents caused by Francisella (Pasteurella) tularensis which may infect farm animals and humans. Biotype A, F. tularensis biovar tularensis, is prevalent in North America associated with tick-borne tularemia in rabbits and is more virulent than biotype B, F. tularensis biovar holarctica (palaearctica), which is found in Asia, Europe, and North America associated with mosquitoes and with water-borne disease in aquatic rodents and rarely causes disease in higher mammals. The clinical disease is very variable, depending on where the infection localizes.