Tularemia, a once-rare disease, is on the rise in the United States as the weather warms and dogs are out and about with their humans. Both dogs and people can be infected with tularemia.

Originally discovered in 1937 by the Japanese, Tularemia is named after a particularly widespread 1911 outbreak in Tulare County, California. Not limited to Western states, Tularemia is especially prevalent in the Midwest, although it is found in every state except Hawai’i.

Tularemia, a.k.a. deerfly or rabbit fever, affects more than 250 species worldwide, including dogs and their humans, cats, deer, rabbits, and other warm-blooded wild animals. It is caused by two strains of the bacterium Francisella tularensis. The common North American strain, Type A, has a mortality rate in humans of 5% to 35% if left untreated. The less virulent Type B, more common to Eurasia as well as North America and associated with water-borne infections and aquatic animals, has a more complex life cycle than does Type A.

As I wrote in my column in the October 2012 issue of the AKC Gazette, “F.  tularensis is transmitted by fleas, deer flies (Chrysops discalis), mosquitos, and four kinds of ticks: Pacific Coast tick (Dermacentor occidentalis), American dog tick (D. variabilis), Rocky Mountain wood tick (D. andersoni), and Lone Star tick (Ambylomma americanum). Incubation period after a bite by an infected carrier is one to fourteen days. Other means of spreading the infection include eating or handling infected animals, drinking or swimming in contaminated water, or inhaling  aerosolized bacteria. Hunters should wear gloves while dressing game. Human to human transmission of Tularemia is rare.”

Dogs and cats can contract Tularemia from carrier insect bites; those who are allowed to hunt, either alone or accompanied by a person, can be infected by eating or carrying infected birds, rabbits, and other rodents. Cats are more susceptible to Tularemia than dogs, as are puppies and kittens; the resultant fever is greater in these animals than in adult dogs.

Human Tularemia infection can occur from flea, tick, or fly bites; from eating undercooked deer, rabbit, or other game meat; and through broken skin by direct contact with an infected animal or its carcass. Hunters, beware!   F. tularensis is a particularly tenacious bacterium that can exist in frozen rabbit or deer meat for over three years (time to clean out your freezer!). It can live for weeks at very low temperatures in water, moist soil, hay, straw, or decaying animal carcasses. It is also a virulent bacterium, with as few as five to fifteen bacteria producing the disease.

Dogs are more resistant to Tularemia than humans. In dogs, Tularemia symptoms include loss of appetite, listlessness, low  fever, and sometimes jaundice. Lymph nodes enlarge and abscesses form in liver and spleen in severe cases, and death can occur rapidly. Cats are more susceptible to Tularemia than dogs, having higher fevers; puppies and kittens are affected more severely than adults. Diagnosis is by blood tests, although antibodies may not develop immediately. Unfortunately, diagnosis is more often by necropsy because of the animal expiring before Tularemia is suspected. There is no proven effective treatment for the disease in dogs, although streptomycin, gentamicin, tetracycline, and chloramphenicol have been used successfully in some cases.

Humans may die from severe forms of Tularemia. Humans usually develop enlarged lymph nodes, with lesions at carrier insect bite sites. If F. tularensis bacteria are ingested either by eating undercooked game or from unwashed hands after handling an infected animal or carcass, further symptoms can include vomiting, diarrhea, and intestinal pain.

Treatment for humans with tetracycline and chloramphenicol have been associated with relapses in people. A vaccine previously available to high-risk people such as laboratory personnel is under review for animals and humans.

There is no home pet care for Tularemia; diagnosed pets require immediate veterinary care. Also, diagnosed animals should be handled carefully with gloves because the infectious disease is transmitted easily to humans. Recovery in dogs and humans confers long-lasting immunity to Tularemia.

© Suzanne T. Smith, 2015