Diseases
This section will focus on deseases that primarily affect wild populations. Disease has been the primary means of population control for European rabbits since the beginning of 19th century, when human hunting began to decrease, and feral populations began to spin out of control. Diseases like tularemia, myxomatosis, and calicivirus have had a huge impact on both rabbit and man, and no natural history would be complete without a look at these important factors.Tularemia
Discovered in 1837 in Japan, tularemia is named after Tulare County, California, where it was described in 1911 by Dr. Edward Francis. Tularemia is caused by gram-negative coccobacillus. The bacterium, Francisella tularensis, was named in honor of Dr. Edward Francis. Tularemia is found worldwide in over a hundred species, that include mammals, foul, and even insects. Some animals that can be carriers are groundhogs, meadow mice, ground squirrels, tree squirrels, coyotes, possums, beavers, sheep, various game birds, and people. [116] [117] In the United States a total of 1,368 human cases of tularemia were reported to the CDC from 44 states between 1990-2000. [118] The two common ways for humans to contract tularemia are from insect bites and direct contact. A bite from an infected tick, deerfly (Chrysops discalis), or mosquito will be followed by the sudden onset of pain and fever. Direct contact with an infected rabbit carcass, if the skin is broken by a cut, or other abrasion, can also lead to infection. Less common ways of contracting the disease are contaminated water, inhaling dust, or handling pelts. Human to human transmission is rare. [119] The treatment of tularemia starts with prevention. Those that are at a high risk of contracting the disease should get vaccinated. Untreated "Type B" tularemia has a mortality rate of about 5-15%. This increases to about 35% with the typhoidal form "Type A." With antibiotics, mortality rates lower to about 1%. Most people will have long-term immunity after recovering from tularemia, although reinfection has occasionally been reported. [120] For those that hunt wild rabbits, or other game that could be infected with tularemia, latex gloves should be worn when handling the carcass and the meat should be cooked thoroughly before eating. [121]
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Myxomatosis
Discovered in laboratory rabbits in Montevideo, Uruguay, in 1896, myxomatosis is caused by the myxoma virus which is a pox virus. [122] [123] The virus was present in the native South American rabbit population, which tolerated it well. However, by 1919 experiments in Britain and Australia showed that European rabbits had a 99% mortality rate when exposed to the disease. In 1950-51 the disease swept through Australia killing off 90% of European rabbits which were fast taking over the country. In 1952, myxomatosis was deliberately introduced to France by a retired physician. Myxomatosis arrived in Britain one year later, in 1953, where it killed 99% of Britain's wild rabbits. [124] [125] The primary vector by which the disease is spread, among rabbits, is by direct or indirect contact with infected fleas and mosquitoes. Symptoms are oedema of the head, ears, eyelids, genitalia, a milky oculonasal discharge, and later diffuse oedematous cutaneous swellings (pseudotumours). [126] [127] Death occurs within 10 days, and is very painful. Today, myxomatosis is still present in rabbit populations in most of the world, but less than 60% of infected animals will die from it due to the immunity the population has aquired through the natural selection of multiple generations. [128] It should also be noted that myxomatosis is not dangerous to humans, as it only affects rabbits. [129]Calicivirus Disease
Also known as rabbit hemorrhagic disease (RCD) and viral hemorrhagic disease (VHD), it is a highly contagious virus that has a 90% mortality rate in infected animals. [130] [131] RCD was discovered in China in 1984. Since then, it has become a worldwide epidemic. An outbreak occurred in Mexico in 1988, but was eradicated by 1992. [132] From China it spread to Europe, arriving in the UK in 1992. [133] Also, parts of Asia and Africa have been affected. In 1993 the disease struck Cuba, and has been at epidemic proportions ever since. Because of a laboratory accident in southern Australia, the virus escaped in 1995, and in a period of 8 weeks killed 10 million rabbits. [134] The next year, in 1996, RCD was officially released at Cranbrook West Australia on October 18. [135] Death occurs within approximately 1-3 days. [136] RCD is a hearty virus that can be transmitted by contact with infected rabbits, their excreta, rabbit products, insects, rodents, and contaminated objects. In addition, if a rabbit survives the disease it can become a carrier, spreading the disease to other rabbits. Killed virus vaccines are available to protect domestic rabbits, and are used in Europe, New Zealand, and Australia. [137]
Written by Samuel Fall
Copyright © 2008 Rabbit Pictures & Facts
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Image Source for Eastern cottontail at top of page: William R. James, U.S. Fish and Wildlife Service.
Image Source for cottontail at bottom of page: Clinton & Charles Robertson / License under Creative Commons 2.0.
Copyright © 2008 Rabbit Pictures & Facts
Member of Fohn.net
Image Source for Eastern cottontail at top of page: William R. James, U.S. Fish and Wildlife Service.
Image Source for cottontail at bottom of page: Clinton & Charles Robertson / License under Creative Commons 2.0.