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Rabies

Livestock Infectious Diseases

Rabies in North America


Preface...

"Rabies", a part of the vernacular  that brings mental images of great suffering and significant monetary loss to most of Rural North America.  Most of us have had at least one experience of rabies in our respective lifetimes.  Whether it be a neighbors horse or a child's kitten, we have been there and done that.  This article attempts to bring forth a greater understanding of the virus in it's various manifestations.  It is not the intent of this essay to either sensationalize nor to minimize the impacts of this most horrible of afflictions.
Preparedness, awareness and observation are the key to preventing losses, both monetary and emotional, when dealing with the Rabies Virus.
In the case of Preparedness, vaccinations of at risk animals (and people) should be throughly considered.
Awareness of the clinical symptoms is paramount, but awareness of the Rabies Virus reservoir in local geographic area is also quite very important.
Observation of local wildlife will give one a sense of the depth of the virus reservoir in one's particular area.  For example, the author has personally encountered about five cases of rabies in local wildlife over a twenty-three year period; and, one human case as well as three cases of rabies in domestic animals over the same period.

From Wikipedia:

Rabies (/ˈrbz/; from Latin: rabies, "madness") is a viral disease that causes acute encephalitis in warm-blooded animals.  The disease is zoonotic, meaning it can be transmitted to humans from another species (such as dogs), commonly by a bite from an infected animal. Rabies is nearly always fatal in humans if post-exposure prophylaxis is not administered before the onset of severe symptoms. The rabies virus infects the central nervous system, ultimately causing disease in the brain and death.

The rabies virus travels to the brain by following the peripheral nerves. The incubation period of the disease is usually a few months in humans, depending on the distance the virus must travel to reach the central nervous system  Once the rabies virus reaches the central nervous system and symptoms begin to show the infection is rarely treatable and usually fatal within days.

Early-stage symptoms of rabies are malaise, headache, and fever, progressing to acute pain, violent movements, uncontrolled excitement, depression, and hydrophobia The patient may experience periods of mania and lethargy eventually leading to coma. The primary cause of death is usually respiratory insufficiency.

Rabies causes about 55,000 human deaths annually worldwide 95% of human deaths due to rabies occur in Asia and Africa Roughly 97% of human rabies cases result from dog bites.  Animal control and vaccination programs have effectively eliminated domestic dogs as reservoirs of rabies in the United States In several countries, including Australia, Japan, and Singapore, rabies carried by terrestrial animals has been eliminated entirely  While classical rabies has been eradicated in the United Kingdom, bats infected with a related virus have been found in the country on rare occasions.

History of the Rabies Virus in North America in Brief  2

Since the 1950s raccoons have continued to be an important reservoir for the circulation of rabies in the south-eastern States of North America. In addition, three strains of RV seem to cause disease in skunks in the north and south central States and in California. The disease spread in the 1950s, affecting foxes across Canada and in New England. Although rabid foxes have declined in Canada as a result of successful baiting strategies, Alaska still harbors the virus in the red and arctic fox populations.

In the United States over the past 40 years, most of the reports of rabies have been in wild rather than domestic animals. During 1998, wild animals accounted for 92.4% of all cases reported to the Centers for Disease Control and Prevention. Raccoons are the species reported most frequently to harbor the disease (40.6%), followed by skunks and bats (29.4% and 14% respectively). Foxes accounted for 5.4%. Outbreaks of rabies infections in terrestrial mammals inclusive of skunks, foxes, raccoons and coyotes are found in broad geographic regions across the US. Hawaii is a unique State in that it has never reported an indigenously acquired human or animal case of rabies.

Interestingly, from 1998 to 1999, cases of rabies in feline, canine and equine species decreased by 1.4%, 1.8% and 20.7%, respectively, whereas those in bovine, ovine and porcine species increased by 16.4%, 12.5% and 200.0%. The two States reporting the highest number of rabid domestic animals were Iowa (57) and Texas (54)  For the first time, a bat-associated RV was isolated from a catin Maryland

In North America, bat rabies is caused by genotype 1 viruses. The main species involved are Eptesicus fuscus, the big brown bat; Tadarida brasiliensis, the Brazilian (Mexican) free-tailed bat; Myotis lucifugus, the little brown bat; Lasiurus cinereus, the hoary bat; Lasionycteris noctivagans, the silver-haired bat, L. borealis, the red bat; and Pipistrellus hesperus, the western pipistrelle.


Geographic Distribution of Rabies in the United States 3

Wild animals accounted for 92% of reported cases of rabies in 2010. Raccoons continued to be the most frequently reported rabid wildlife species (36.5% of all animal cases during 2010), followed by skunks (23.5%), bats (23.2%), foxes (7.0%), and other wild animals, including rodents and lagomorphs (1.8%). Reported cases decreased among all wild animals during 2010.

Outbreaks of rabies infections in terrestrial mammals like raccoons, skunks, foxes, and coyotes are found in broad geographic regions across the United States. Geographic boundaries of currently recognized reservoirs for rabies in terrestrial mammals are shown on the map above and left:

Reliable information for the geographic distribution of the Rabies Virus in Mexico and Canada will be added when available.


Behavior of Infected Animals 4


Clinical signs of rabies are rarely definitive. Rabid animals of all species usually exhibit typical signs of CNS disturbance, with minor variations among species. The most reliable signs, regardless of species, are acute behavioral changes and unexplained progressive paralysis. Behavioral changes may include sudden anorexia, signs of apprehension or nervousness, irritability, and hyperexcitability (including priapism). The animal may seek solitude. Ataxia, altered phonation, and changes in temperament are apparent. Uncharacteristic aggressiveness may developa normally docile animal may suddenly become vicious. Commonly, rabid wild animals may lose their fear of humans, and species that are normally nocturnal may be seen wandering about during the daytime. 

The clinical course may be divided into 3 general phasesprodromal, acute excitative, and paralytic/endstage. However, this division is of limited practical value because of the variability of signs and the irregular lengths of the phases. During the prodromal period, which lasts ∼13 days, animals show only vague nonspecific signs, which intensify rapidly. The disease progresses rapidly after the onset of paralysis, and death is virtually certain a few days thereafter. Some animals die rapidly without marked clinical signs.
The term furious rabies refers to animals in which aggression (the acute neural excitative phase) is pronounced. Dumb or paralytic rabies refers to animals in which the behavioral changes are minimal, and the disease is manifest principally by paralysis.

Furious Form
This is the classic mad-dog syndrome, although it may be seen in all species. There is rarely evidence of paralysis during this stage. The animal becomes irritable and, with the slightest provocation, may viciously and aggressively use its teeth, claws, horns, or hooves. The posture and expression is one of alertness and anxiety, with pupils dilated. Noise may invite attack. Such animals lose caution and fear of humans and other animals. Carnivores with this form of rabies frequently roam extensively, attacking other animals, including people, and any moving object. They commonly swallow foreign objects, eg, feces, straw, sticks, and stones. Rabid dogs may chew the wire and frame of their cages, breaking their teeth, and will follow a hand moved in front of the cage, attempting to bite. Young pups can seek human companionship and are overly playful, but bite even when petted, usually becoming vicious in a few hours. Rabid skunks may seek out and attack litters of puppies or kittens. Rabid domestic cats and bobcats can attack suddenly, biting and scratching viciously. As the disease progresses, muscular incoordination and seizures are common. Death results from progressive paralysis.

Paralytic Form
This is manifest by ataxia and paralysis of the throat and masseter muscles, often with profuse salivation and the inability to swallow. Dropping of the lower jaw is common in dogs. Owners frequently examine the mouth of dogs and livestock searching for a foreign body or administer medication with their bare hands, thereby exposing themselves to rabies. These animals may not be vicious and rarely attempt to bite. The paralysis progresses rapidly to all parts of the body, and coma and death follow in a few hours.

Species Variations
Cattle with furious rabies can be dangerous, attacking and pursuing humans and other animals. Lactation ceases abruptly in dairy cattle. The usual placid expression is replaced by one of alertness. The eyes and ears follow sounds and movement. A common clinical sign is a characteristic abnormal bellowing, which may continue intermittently until shortly before death. 

Horses and mules frequently show evidence of distress and extreme agitation. These signs, especially when accompanied by rolling, may be interpreted as evidence of colic. As in other species, horses may bite or strike viciously and, because of their size and strength, become unmanageable in a few hours. People have been killed outright by such animals. These animals frequently have self-inflicted wounds.
Rabid foxes and coyotes often invade yards or even houses, attacking dogs and people. One abnormal behavior that can occur is demonstrated by the fox that attacks a porcupine; finding a fox with porcupine quills can, in many cases, support a diagnosis of rabies.
Rabid raccoons and skunks typically show no fear of humans and are ataxic, frequently aggressive, and active during the day, despite their often crepuscular nature. In urban areas, they may attack domestic pets.
In general, rabies should be suspected in terrestrial wildlife acting abnormally. The same is true of bats that can be seen flying in the daytime, resting on the ground, paralyzed and unable to fly, attacking people or other animals, or fighting.
Rodents and lagomorphs rarely constitute a risk for rabies virus exposure. However, each incident should be evaluated individually. Reports of laboratory-confirmed rabies in woodchucks are not uncommon in association with the raccoon rabies epizootic in the eastern USA.


Prevention and Mitigation 4

Comprehensive guidelines for control in dogs have been prepared internationally by the World Health Organization and in the USA by the National Association of State Public Health Veterinarians (NASPHV). They include the following: 1) notification of suspected cases, and euthanasia of dogs with clinical signs and dogs bitten by a suspected rabid animal; 2) reduction of contact rates between susceptible dogs by leash laws, dog movement control, and quarantine; 3) mass immunization of dogs by campaigns and by continuing vaccination of young dogs; 4) stray dog control and euthanasia of unvaccinated dogs with low levels of dependency on, or restriction by, humans; and 5) dog registration.

The Compendium of Animal Rabies Control, compiled and updated annually by the NASPHV, summarizes the most current recommendations for the USA and lists all USDA-licensed animal rabies vaccines that are marketed in the USA. Many effective vaccines, such as modified live virus, recombinant, and inactivated types, are available for use throughout the world; in the USA, no modified live rabies virus vaccines are currently marketed (for any species). Recommended vaccination frequency is every 3 yr, after an initial series of 2 vaccines 1 yr apart. Several vaccines are also available for use in cats, and a few for use in ferrets, horses, cattle, and sheep. Because of the increasing importance of rabies in cats, vaccination of cats is extremely important. No parenteral vaccine is approved for use in wildlife. Protective immunity from the commercially available vaccines for domestic species has not been definitively demonstrated in these species.
Until recently, the control of rabies in wildlife populations relied on population reduction of wildlife in an attempt to reduce the contact rate between susceptible animals; however, this proved difficult and often not publicly acceptable, ecologically sound, economically warranted, or programmatically effective. In Europe and Canada, use of oral vaccines distributed in baits to control fox rabies has been widespread and effective. The disease in foxes has been eliminated from most of western Europe and curtailed significantly in Ontario. Use of a vaccinia-rabies glycoprotein recombinant virus vaccine in the USA has successfully eliminated coyote rabies in southern Texas and has limited the western expansion of raccoon rabies from the eastern USA. The license limits use of the vaccine to state or federal rabies programs; it is not available to private veterinarians or for individual animal use. Together with other vaccines, it is also being used to assist in the control of dog rabies in developing countries.

Where terrestrial wildlife or bat rabies is known to occur, any animal bitten or otherwise exposed by a wild, carnivorous mammal (or a bat) not available for testing should be regarded as having been exposed to rabies. The NASPHV recommends that any unvaccinated dog, cat, or ferret exposed to rabies be euthanized immediately. If the owner is unwilling to do this, the animal should be placed in strict isolation (ie, no human or animal contact) for 6 mo and vaccinated against rabies 1 mo before release. If an exposed animal is currently vaccinated, it should be revaccinated immediately and closely observed for 45 days.

Talking to your Veterinarian about Rabies Vaccination  for Dairy Stock

Consideration should be given to vaccinating livestock that are particularly valuable. Animals for which there is a licensed rabies vaccine (horses, cattle and sheep), thathave frequent contact with humans (e.g. petting zoos, fairs, riding stables, shows,exhibitions, etc.) should be currently vaccinated against rabies

If your veterinarian is reluctant to vaccinate dairy cattle or dairy goats, simply refer he or she to this article:  http://www.cdc.gov/mmwr/preview/mmwrhtml/00056759.htm which lists several facts relating to the subject:
:
  • During 1990-1996, CDC received reports of 22 incidents of mass human exposures to rabid or presumed-rabid animals in the United States, resulting in 1908 persons receiving PEP (median: 33 persons per incident) (4). In Massachusetts during 1991-1995, the median cost for PEP was $2376 per person, including physician and facility charges (5). Prolific administration of PEP in response to these incidents strains the availability of rabies biologics, especially human rabies immune globulin, which has a short shelf-life and tightly controlled distribution by the manufacturers.

  • An average of 150 rabid cattle have been reported to CDC in the United States each year since 1990 (6). In addition to concerns about rabies transmission from animals to humans through bites, rabid livestock raise the potential for foodborne transmission. The National Association of State Public Health Veterinarians recommends against consuming tissues and milk from rabid animals (2). However, because rabies virus is inactivated by temperatures below those used for cooking and pasteurization, eating cooked meat or drinking pasteurized milk from a rabid animal is not an indication for PEP.

  • Rabies virus can be transmitted by direct contact with infected material, such as saliva from an animal infected with rabies, and mucous membranes, including the oral and gastric mucosae (7). In addition to saliva and neural tissue, rabies virus also has been detected in the kidney, prostate, pancreas, and other tissues and body fluids (8). However, saliva and neural tissue are the primary proven vehicles for rabies virus in naturally occurring cases. Anecdotal reports exist of rabies transmission by ingestion of milk from rabid animals (e.g., from a rabid sheep to a nursing lamb) (7). In these reports, the more conventional routes (e.g., bite or mucous membrane exposure) could not be completely excluded.

Additionally there is this from Colorado State University:

CSU Veterinarians Recommend Annual Rabies Vaccine for Livestock, Horses

Colorado State University veterinarians are recommending that livestock and horses be vaccinated for rabies due to an increased number of infected skunks in the state.
 
While livestock or horses contracting rabies is still uncommon in Colorado, it is extremely important now more than ever to work to prevent animals from contracting the disease, said Dr. Bruce Connally, a veterinarian with the Colorado State University Veterinary Teaching Hospitals equine section. Its important because, if an animal is exposed to rabies, the symptoms can be difficult to distinguish from other illnesses, and, while it is being diagnosed, the animal and people exposed to it are at risk of contracting the disease.
 
While bats have spread rabies in Colorado for many years, rabies spread through other wildlife has typically been more common in Eastern states. Over the last several years, more skunks in Colorado have become infected, which has resulted in an increased infection rate and risk of infection to livestock and horses. This is due in part to habitat changes and human movement of wild animals that spread the disease into areas previously uninfected.
 
Clinicians at the Veterinary Teaching Hospital, in the College of Veterinary Medicine and Biomedical Sciences, now recommend horses and livestock, particularly pet livestock such as llamas and alpacas, be vaccinated once a year. They also recommend vaccination of commercial production livestock in locations where there is high skunk activity. Companion pet owners are urged to vaccinate their cats and dogs as all warm-blooded animals, including humans, can be infected with rabies.
 
Wounds from a rabid skunk bite may not be visible or easy to detect on livestock or horses, and symptoms of rabies mimic other more common illnesses and can be confused with regular colic or a foot or leg injury. Rabies also can enter the body through cuts or scratches. Rabies can be spread to people through contact with saliva or bodily fluids.
 
A rabies bite to an animal that has not been vaccinated is invariably fatal, Dr. Connally said. The animals horses and livestock will die. If you value them, invest in a vaccine.
 
Signs of rabies in animals include:
 
  • Changed or altered behavior, including depression
  • Acting nervous or agitated
  • Vicious, unprovoked attacks
  • Excessive salivation and difficulty swallowing
  • Roaming or separation from the herd
  • Unusual sexual activity
  • Abnormal vocalizations
  • Ascending paralysis, normally beginning in the hind limbs
  • Signs of colic
  • Self mutilation
  • Sensitivity to light
Vaccines range in price for different animals. Cattle vaccines, which are also used for camelids (llamas and alpacas), are available for less than $5 each, and horse vaccines range from $10 to $15, depending upon the number of animals vaccinated. Rabies vaccinations last for a year.
 
If you believe your animal has been exposed to rabies, or possibly bitten by a rabid animal, immediately contact your veterinarian. For information on human rabies illness, see www.cdc.gov or www.cdphe.state.co.us. For information on what to do if you have been bit by an unvaccinated animal or suspect you have otherwise been exposed to rabies, call your local health department.

Talking to your Doctor about Prophylactic Vaccination for yourself or family members 1

Background 2
Until recently it was difficult to identify which strains of RV were causing human disease. This has changed with the advent of molecular diagnostic tools such as nucleotide analysis, which also provide clues to the source of the virus. It now seems that a large proportion of human rabies infections in the United States are transmitted by bat bites. Some people when bitten ignore the danger and take no action; many are simply unaware of the biteperhaps because they are asleep when it happened. Also, parents may not know that their children have been in contact with bats.

Since the 1900s, the number of deaths from rabies in North America has fallen from 100 or more each year to just one or two cases. Much of the decline dates from the 1940s, when vaccination and animal control programs were set up. In the early 1940s, there were about 40 cases each year. This figure decreased to a total of 99 for the entire decade in the 1950s, and then dropped further to 15 in the 1960s, 23 in the 1970s, 10 in the 1980s and 22 from 1990 to 1996. Widespread vaccination of canine pets in the 1950s was partly responsible for the decrease in human cases in subsequent years. The vaccination campaigns implemented in the 1940s all but eliminated the circulation of canine strains of genotype 1 RV by the 1960s. However, the late 1970s and early 1980s witnessed the re-emergence of a variant well adapted to dogs in south Texas, thereby increasing the risk to human beings.

4 human cases were reported in 1997 (Montana, Washington, Texas and New Jersey) and just 1 case in 1998 (Virginia). No human deaths were recorded in the USA for 1999 but in 2000 there were 5, reported from California, New York, Georgia, Minnesota and Wisconsin plus 1 from Quebec (Canada). The case reported from New York was in a patient who had come from Ghana after being bitten by a dog; all the others were thought to be associated with bats.

There is a very distinct difference between the prophylactic vaccination series and the post-exposure vaccination series.  This paragraph only discuses the the prophylactic vaccination series as there is no rational argument on the subject of the need of and the requirement for post exposure vaccination, nor is there any doubt to the fatal outcome for one refusing said vaccination.

Pre-exposure & post-exposure Vaccination Defined 2


Pre-exposure

Safe and potent rabies vaccines are available for use in man. Both pre-exposure and post-exposure treatments for rabies have been harmonized across Europe and North America following the guidelines set by the WHO. The vaccine currently employed in the UK is a rabies human diploid cell vaccine (HDCV). Easily accessible, it is a freeze-dried suspension of Wistar RV strain PM/WI 38 1503-3M. Pre-exposure prophylaxis is routinely offered to those whose occupation may lead to exposure to rabies viruses. These include workers at animal quarantine centers, at zoos, at research and acclimatization centres where non-human primates and other imported animals are housed, and certain customs and excise officers, veterinary and technical staff in the State Veterinary Services, inspectors appointed by local authorities under the Animal Health Act 1981, bat handlers and laboratory workers. The recommended schedule for primary pre-exposure immunization with HDCV is three doses given by deep subcutaneous or intramuscular injection in the deltoid region on days 0, 7 and 28. The antibody response may be lower with gluteal injection. Travelers to rabies endemic areas are offered two doses by deep subcutaneous or intramuscular injection four weeks apart, and this can be expected to give immunity in 98% of recipients. This level of protection may be acceptable if post-exposure treatment is likely to be readily available. However, for those travelers with continued exposure to rabies viruses a further dose should be given 6-12 months later.

Post-exposure

The treatment regimen after exposure depends on several factors. Daily doses of vaccine in the abdomen are no longer necessary. The strategy recommended by WHO is essentially as follows. Patients who have had a pre-exposure course of HDCV should be given two subcutaneous or intramuscular doses of HDCV in the deltoid region, one on day 0 and one between days 3 and 7. For children, vaccine can be delivered in the anterolateral aspect of the thigh.

Previously unimmunized individuals should be given, in addition to vaccine, rabies immunoglobulin in a dose of 20 IU/kg body weight. Up to half the dose should be infiltrated in and around the wound after cleansing and the rest by intramuscular injection. HDCV should be delivered by subcutaneous or intramuscular injection (not the buttocks), on days 0, 3, 7, 14, and 30.

In argument against receiving the prophylactic vaccination series
  • First, unless you are an animal control officer, a veterinarian or veterinarian assistant, a laboratory technician or work in some other vocation that routinely exposes one to the virus, your doctor is unlikely to go for human prophylactic vaccination.
  • Secondly, the cost of the prophylactic vaccination series is quite steep for most, averaging about $500 for the three dose series that only gives protection for about two years.
  • Finally, I truly believe that one should question the intra-muscular introduction of anything into one's body that glows purple (without black light illumination).
In argument for receiving the prophylactic vaccination series
  • Noting the final bullet of the preceding paragraph, I did in fact take the vaccine in 1992 after coming in contact with two separate rabid raccoons in one shift as the Animal Control Officer for the City of Salem, Missouri.  This was a personal choice on my part and was not mandated by either policy or superior's dictates.  The city of Salem paid out $1,100  as their part of the cost-share for the three shot series that I received via the local county health department.
  • If one is routinely in a happenstance wherein possible or probable exposure to the rabies virus can be expected, the receiving of the prophylactic vaccination series does substantially contribute to one's peace of mind.
  • The monetary savings in being vaccinated pre-exposure vice post-exposure is self evident; i.e., lab tests versus likely hospitalization and lost work time.

Videos of Rabies infected people and animals

The below videos may be are emotionally disturbing to the author at least; however, they do show various symptoms of rabies infections:  Therefore, I must recommend the watching of same to simply educate one's self and to increase one's awareness.  Accordingly and on a personal note, since the author lives in a Rabies prone area, even the authors grand-children that live on the farm and that are also old enough to understand the videos will be watching same.
Use of the full screen option ( { } icon) is recommended.
















Further Research Sources:


Sources for this Essay:

  1. http://publichealth.lacounty.gov/vet/rabiesmanualpdfs/pplerabvac.pdf
  2. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1279140/
  3. http://www.cdc.gov/rabies/location/usa/surveillance/wild_animals.html
  4. http://www.merckmanuals.com/vet/nervous_system/rabies/overview_of_rabies.html
  5. http://en.wikipedia.org/wiki/Rabies




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