Rabies in animals

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Rabies is a viral zoonotic neuroinvasive disease which causes inflammation in the brain and is usually fatal. Rabies primarily infects mammals and is caused by the rabies virus. Animals with rabies suffer deterioration of the brain and tend to behave bizarrely and often aggressively, increasing the chances that they will bite another animal or a person and transmit the disease.

Stages of disease[edit]

Three stages of rabies are recognized in dogs and other animals.

  1. The first stage is a one- to three-day period characterized by behavioral changes and is known as the prodromal stage.
  2. The second stage is the excitative stage, which lasts three to four days. It is this stage that is often known as furious rabies due to the tendency of the affected animal to be hyperreactive to external stimuli and bite at anything near.
  3. The third stage is the paralytic stage and is caused by damage to motor neurons. Incoordination is seen due to rear limb paralysis and drooling and difficulty swallowing is caused by paralysis of facial and throat muscles.This disables the victim's ability to swallow, which causes saliva to pour from the mouth also the reason bites are the most clear way for the infection to spread is because the virus is most concentrated in the throat and cheeks causing major contamination to saliva. Death is usually caused by respiratory arrest.[1]

Mammals[edit]

For rabies in humans, see rabies.

Bats[edit]

The problem of bat-transmitted rabies is found over most of North and South America but it was first closely studied in Trinidad in the West Indies. This island had a known reputation for bat rabies, which took a significant toll of livestock and humans alike. In the 10 years from 1925 and 1935, 89 people and thousands of livestock had died from it—“the highest human mortality from rabies-infected bats thus far recorded anywhere.” [2]

In early 1931, Dr. H. Metivier, a Veterinary surgeon, established the connection between the bites of bats and paralytic rabies. In September 1931, Dr. Joseph Lennox Pawan of Trinidad in the West Indies, a Government Bacteriologist, found Negri bodies in the brain of a bat with unusual habits. In 1932, Dr. Pawan first discovered that infected vampire bats could transmit rabies to humans and other animals.[3][4] In 1934 the Trinidad and Tobago Government began a program of vampire bat control, shooting, netting, trapping, dynamiting nesting colonies and poisoning, while encouraging the screening off of livestock buildings and free vaccination programs for exposed livestock.

After the opening of the Trinidad Regional Virus Laboratory in 1953, basic research on bats and rabies progressed rapidly under the able direction of Arthur Greenhall, who demonstrated that at least 8 species of bats in Trinidad had been infected with rabies - particularly the Common Vampire Bat, Desmodus rotundus (which “will attack any warm blooded creature”), the rare White-winged Vampire Bat, Diaemus youngi, (which “appears to have a special preference for birds and goats”), as well as two abundant species of Fruit Bats: the Seba's Short-tailed Bat or Short-tailed Fruit Bat, Carollia perspicillata, which commonly roosts with Vampires, and the Jamaican Fruit Bat, Artibeus jamaicensis.[5]

Non-bite transmission of rabies in people has been reported by the CDC,[6] and experimentally demonstrated with a high efficiency in susceptible animals placed in bat-proof and insect-proof cages in a cave with bat colonies by Constantine in Frio Cave, Texas, as early as 1960.[7] In 1967, rabies virus was isolated from the air in the same cave,[8] presumably passed by the bats urinating, potentially forming a source for infection of other susceptible animals, and presenting a hazard to researchers and spelunkers. While the risks may be low, they are deserving of further study and monitoring.[9]

The United Kingdom, which has stringent regulations on the importation of animals, had also been believed to be entirely free from rabies until 1996 when a single Daubenton's bat was found to be infected with a rabies-like virus usually found only in bats: European Bat Lyssavirus 2 (EBL2). There were no more known cases until September 2002 when another Daubenton's bat tested positive for EBL2 in Lancashire. A bat conservationist who was bitten by the infected bat received post-exposure treatment and did not develop rabies.

Then in November 2002 David McRae (1947–2002), a Scottish bat conservationist from Guthrie, Angus was bitten on the ring finger of his left hand by a bat, thereby becoming the first human to contract rabies in the United Kingdom since 1902. He subsequently died in hospital [10] from EBL2 rabies on November 24, 2002.[11]

In November 2004, Jeanna Giese, a fifteen-year old girl from Fond du Lac, Wisconsin, became one of only six humans known to have survived rabies after the onset of symptoms, and the first known instance of a human surviving rabies without vaccine treatment. Giese's disease was already too far progressed for the vaccine to help, and she was considered too weak to tolerate it. Doctors at the Children's Hospital of Wisconsin in Wauwatosa, a suburb of Milwaukee, achieved her survival with an experimental treatment that involved putting the girl into a drug-induced coma, and administering a cocktail of antiviral drugs. Giese had symptoms of full-blown rabies when she sought medical help, thirty-seven days after being bitten by a bat. Her family did not seek treatment at the time because the bat seemed healthy. Jeanna regained her weight, strength, and coordination while in the hospital. She was released from the Children's Hospital of Wisconsin on January 1, 2005.

On May 12, 2006, Harris County, Texas Health Department officials reported that a teenage boy, Zachary Jones of Humble, Texas, had died of rabies at Texas Children's Hospital in Houston, Texas. Zachary had contracted the disease after a bat flew in his bedroom and bit him in his sleep. He was unaware he had been bitten and was not hospitalized until he developed symptoms several weeks later. He died at Texas Children's Hospital after an attempt to cure the disease through a drug-induced coma, similar to that of Jeanna Giese.

On November 2, 2006 a 10-year-old girl in Bourbon, Indiana, America died of rabies. The Indianapolis Star reports that she was bitten by a bat in June 2006.

In August 2006, a 73 year old rural resident located east of Edmonton, Alberta, Canada was bitten by a bat while he slept. He ignored the bite and became symptomatic in January 2007. Diagnosed with rabies in March 2007, he was treated with the Milwaukee protocol, but died April 26, 2007.

On August 6, 2006, 950 Girl Scouts were urged to receive rabies shots by the Girl Scouts of the USA. The nine hundred and fifty girls had attended a camp in Virginia, U.S.A. in July, and had reported seeing bats in their cabins. Even though infections were relatively unlikely, the GSA offered to pay for the shots, at a cost of nearly two million dollars. The Centers for Disease Control reports 27 cases of human rabies caused by the bat variant rabies virus in the United States from 1990 to 2002.[12]

On December 8, 2007, a 34-year-old Dutch medical doctor died from rabies. According to Dutch media, the woman, who worked at the Amsterdam Academic Medical Center (AMC), had been attacked by a small bat while on holiday in Kenya the previous October. The attack, which occurred at a camping site somewhere between Nairobi and Mombasa, resulted in some bleeding scratches on her nose. She was infected with Duvenhage virus and succumbed to severe brain infection.

On August 8, 2008, it was reported that over the course of a year, 38 villagers of Delta Amacuro, Venezuela had died during a suspected outbreak of rabies spread by vampire bats.

In August 2010, a migrant worker died in a Louisiana hospital from a rabid vampire bat bite that occurred while the man was in Mexico.[13]

Dogs[edit]

Close-up of a dog during late-stage ("dumb") paralytic rabies. Animals with "dumb" rabies appear depressed, lethargic, and uncoordinated. Gradually they become completely paralyzed. When their throat and jaw muscles are paralyzed, the animals will drool and have difficulty swallowing.

Rabies has a long history of association with dogs. The first written record of rabies is in the Codex of Eshnunna (ca. 1930 BC), which dictates that the owner of a dog showing symptoms of rabies should take preventive measure against bites. If a person was bitten by a rabid dog and later died, the owner was fined heavily.[14]

Three stages of rabies are recognized in dogs. The first stage is a one- to three-day period characterized by behavioral changes and is known as the prodromal stage. The second stage is the excitative stage, which lasts three to four days. It is this stage that is often known as furious rabies due to the tendency of the affected dog to be hyperreactive to external stimuli and bite at anything near. The third stage is the paralytic stage and is caused by damage to motor neurons. Incoordination is seen due to rear limb paralysis and drooling and difficulty swallowing is caused by paralysis of facial and throat muscles. Death is usually caused by respiratory arrest.[1]

Opossums[edit]

Experimental studies of rabies infection in the Virginia opossum have shown the importance of the mode of transmission. Opossums became infected when exposed to air-borne virus but were found to be fairly resistant to intramuscular inoculations.[15][16][17] The aerosol transmission of rabies in opossum was investigated following the death from rabies of two men who had visited the Frio Caves, Texas, and did not remember any direct contact with bats.

Rabies cases in the Virginia opossum are spillover cases from other wildlife species such as bats, skunks and the raccoon epizootic in the eastern United States. Cases have been reported across the United States from California to New York.[18][19] In New York state, laboratory confirmed rabies cases in opossums occurred five of the ten years between from 1989 to 1998.

Skunks[edit]

In the U.S., there is currently no USDA-approved vaccine for the strain of rabies that afflicts skunks. When cases are reported of pet skunks biting a human, the animals are frequently killed in order to be tested for rabies.

Humans exposed to the rabies virus must begin post-exposure prophylaxis before the disease can progress to the central nervous system. For this reason, it is necessary to determine whether the animal, in fact, has rabies as quickly as possible. Without a definitive quarantine period in place for skunks, quarantining the animals is not advised as there is no way of knowing how long it may take the animal to show symptoms. Destruction of the skunk is recommended and the brain is then tested for presence of rabies virus.

Skunk owners have recently organized to campaign for USDA approval of both a vaccine and an officially recommended quarantine period for skunks in the United States.[citation needed]

Wolves[edit]

Under normal circumstances, wild wolves are generally timid around humans, though there are several reported circumstances in which wolves have been recorded to act aggressively toward humans.[20] The majority of fatal wolf attacks have historically involved rabies, which was first recorded in wolves in the 13th century. The earliest recorded case of an actual rabid wolf attack comes from Germany in 1557.[20] Though wolves are not reservoirs for the disease, they can catch it from other species. Wolves develop an exceptionally severe aggressive state when infected and can bite numerous people in a single attack. Before a vaccine was developed, bites were almost always fatal. Today, wolf bites can be treated, but the severity of rabid wolf attacks can sometimes result in outright death, or a bite near the head will make the disease act too fast for the treatment to take effect. Rabid attacks tend to cluster in winter and spring. With the reduction of rabies in Europe and North America, few rabid wolf attacks have been recorded, though some still occur annually in the Middle East. Rabid attacks can be distinguished from predatory attacks by the fact that rabid wolves limit themselves to biting their victims rather than consuming them. Plus, the timespan of predatory attacks can sometimes last for months or years, as opposed to rabid attacks which end usually after a fortnight. Victims of rabid wolves are usually attacked around the head and neck in a sustained manner.[20]

Foxes[edit]

Recently (probably from the late 90s, by mentions in press) new symptoms of rabies of wild animals have been observed, namely in foxes. Probably at the beginning of the prodromal stage foxes, who are extremely cautious by nature, absolutely lose wild instincts. Animals come into settlements, reach for people, and behave as if tame.[citation needed] How long such "euphoria" lasts is not known. But even in such status the animal is extremely dangerous, as its saliva and excretions still contain the virus. In an August 2008 blog article,[21] one author observed and photographed such a subject.

Monkeys[edit]

Monkeys, like humans can get rabies. However, they tend to die more quickly than humans. In one study, 9 of 10 monkeys developed severe symptoms or died within 20 days of infection.[22]

Other small mammals[edit]

The most commonly infected terrestrial animals in the U.S.A. are raccoons, skunks, foxes, and coyotes. Any bites by such wild animals must be considered a possible exposure to the rabies virus.

Most cases of rabies in rodents reported to the Centers for Disease Control and Prevention in the U.S.A. have been found among groundhogs (woodchucks). Small rodents such as squirrels, hamsters, guinea pigs, gerbils, chipmunks, rats, and mice and lagomorphs like rabbits and hares are almost never found to be infected with rabies and are not known to transmit rabies to humans.[23]

In the United States, the most commonly reported rabid animal is the domestic cat.[24] In every year since 1990, reported cases of rabies in cats have outnumbered cases of rabies in dogs.[24]

Transport of pet animals between countries[edit]

Main article: Pet passport
Sign at a UK port showing rabies prevention measures aimed at merchant sailors.

Rabies is endemic to many parts of the world, and one of the reasons given for quarantine periods in international animal transport has been to try to keep the disease out of uninfected regions. However, most developed countries, pioneered by Sweden[citation needed], now allow unencumbered travel between their territories for pet animals that have demonstrated an adequate immune response to rabies vaccination.

Such countries may limit movement to animals from countries where rabies is considered to be under control in pet animals. There are various lists of such countries. The United Kingdom has developed a list, and France has a rather different list, said to be based on a list of the Office International des Epizooties (OIE).[citation needed] The European Union has a harmonised list. No list of rabies-free countries is readily available from OIE.[original research?]

In recent years, canine rabies has been practically eliminated in North America and Europe due to extensive and often mandatory vaccination requirements.[citation needed] However it is still a significant problem in Africa, the Middle East, Latin America, and Asia.[25] Dogs are considered to be the main reservoir for rabies in developing countries.[26]

However, the recent spread of rabies in the northeastern United States and further may cause a restrengthening of precautions against movement of possibly rabid animals between developed countries.

See also[edit]

Footnotes[edit]

  1. ^ a b Ettinger, Stephen J.;Feldman, Edward C. (1995). Textbook of Veterinary Internal Medicine (4th ed.). W.B. Saunders Company. ISBN 0-7216-6795-3. 
  2. ^ Goodwin and Greenhall (1961), p. 196
  3. ^ Pawan (1936), pp. 137-156.
  4. ^ Pawan, J.L. (1936b). "Rabies in the Vampire Bat of Trinidad with Special Reference to the Clinical Course and the Latency of Infection." Annals of Tropical Medicine and Parasitology. Vol. 30, No. 4. December, 1936.
  5. ^ Greenhall, Arthur M. 1961. Bats in Agriculture. Ministry of Agriculture, Trinidad and Tobago.
  6. ^ Centers for Disease Control and Prevention (CDC) (December 2004). "Recovery of a patient from clinical rabies--Wisconsin, 2004". MMWR. Morbidity and mortality weekly report 53 (50): 1171–3. PMID 15614231. 
  7. ^ Constantine DG (1962). "Rabies transmission by nonbite route". Public Health Rep 77: 287–9. doi:10.2307/4591470. PMC 1914752. PMID 13880956. 
  8. ^ Winkler, W. G. 1968. "Airborne Rabies Virus Isolation." Bull. Wildlife Disease Assoc. Vol. 4, April 1968, pp. 37-40. Available online at: http://www.jwildlifedis.org/cgi/reprint/4/2/37
  9. ^ Messenger SL, Smith JS, Rupprecht CE (2002). "Emerging epidemiology of bat-associated cryptic cases of rabies in humans in the United States". Clin. Infect. Dis. 35 (6): 738–47. doi:10.1086/342387. PMID 12203172. 
  10. ^ "UK | Scotland | Man dies from rabies after bat bite". BBC News. 2002-11-24. Retrieved 2013-07-30. 
  11. ^ "Rabies victim bit nurses in despair - UK - The Scotsman". News.scotsman.com. 2003-12-19. Retrieved 2013-07-30. 
  12. ^ "Rabies Surveillance". Centers for Disease Control. 2003. Retrieved 2006-11-10. 
  13. ^ "2010 death first U.S. known case of vampire bat rabies virus". CNN. August 12, 2011. Retrieved 2013-08-20. 
  14. ^ Dunlop, Robert H.; Williams, David J. (1996). Veterinary Medicine:An Illustrated History. Mosby. ISBN 0-8016-3209-9. 
  15. ^ Constantine DG, Woodall DF (1966). "Transmission experiments with bat rabies isolates: reactions of certain Carnivora, opossum, rodents, and bats to rabies virus of red bat origin when exposed by bat bite or by intrasmuscular inoculation". Am. J. Vet. Res. 27 (116): 24–32. PMID 5913032. 
  16. ^ Constantine DG 1967 Rabies transmission by air in bat caves. US Pub Health Serv, Publ. 1617
  17. ^ Beamer PD, Mohr CO, Barr TR (1960). "Resistance of the opossum to rabies virus". Am. J. Vet. Res. 21: 507–10. PMID 13797881. 
  18. ^ Krebs JW, Smith JS, Rupprecht CE, Childs JE (1997). "Rabies surveillance in the United States during 1996". J. Am. Vet. Med. Assoc. 211 (12): 1525–39. PMID 9412679. "Erratum". J. Am. Vet. Med. Assoc. 212 (8): 1280. 1998. 
  19. ^ Krebs JW, Noll HR, Rupprecht CE, Childs JE (2002). "Rabies surveillance in the United States during 2001". J. Am. Vet. Med. Assoc. 221 (12): 1690–701. doi:10.2460/javma.2002.221.1690. PMID 12494966. 
  20. ^ a b c "The Fear of Wolves: A Review of Wolf Attacks on Humans". Norsk Institutt for Naturforskning. Retrieved 2008-06-26. 
  21. ^ "Our pages | Dimas-Blog". Dimas.sk6.ru. Retrieved 2013-07-30. 
  22. ^ Weinmann, E.; Majer, M.; Hilfenhaus, J. (1979). "Intramuscular and/or Intralumbar Postexposure Treatment of Rabies Virus-Infected Cynomolgus Monkeys with Human Interferon". Infection and Immunity (American Society for Microbiology) 24 (1): 24–31. 
  23. ^ "Rabies. Other Wild Animals: Terrestrial carnivores: raccoons, skunks and foxes.". 1600 Clifton Rd, Atlanta, GA 30333, USA: Centers for Disease Control and Prevention. Retrieved 2010-12-23. 
  24. ^ a b Cynthia M. Kahn, BA, MA, ed. (2010). The Merck Veterinary Manual (10th ed.). Kendallville, Indiana: Courier Kendallville, Inc. p. 1193. ISBN 0-911910-93-X. 
  25. ^ "Rabies:Introduction". The Merck Veterinary Manual. 2006. Retrieved 2007-08-14. 
  26. ^ Rupprecht, Charles E. (2007). "Prevention of Specific Infectious Diseases: Rabies". Traveler's Health:Yellow Book. Centers for Disease Control and Prevention. Retrieved 2007-08-14. 

References[edit]

  • Baynard, Ashley C. et al. (2011). "Bats and Lyssaviruses." In: Advances in VIRUS RESEARCH VOLUME 79. Research Advances in Rabies. Edited by Alan C. Jackson. Elsevier. ISBN 978-0-12-387040-7.
  • Goodwin G. G., and A. M. Greenhall. 1961. "A review of the bats of Trinidad and Tobago." Bulletin of the American Museum of Natural History, 122.
  • Joseph Lennox Pawan (1936). "Transmission of the Paralytic Rabies in Trinidad of the Vampire Bat: Desmodus rotundus murinus Wagner, 1840." Annual Tropical Medicine and Parasitol, 30, April 8, 1936, pp. 137–156.