Calling it “one of the most concentrated outbreaks of rabies in decades”, New Mexico State Health Department officials have sanctioned door-to-door site visits to farms and ranches in rural areas of Eddy County in deep Southern New Mexico and are recommending selective livestock vaccinations after 32 animals have tested positive for rabies since January, and at least a dozen people are undergoing treatment for possible exposure to the deadly virus.
So far this year the outbreak is concentrated in and around the Carlsbad area and has been limited to rabid skunks and foxes. But last year at least one horse contracted the disease and concerns were being raised over livestock and domestic animals as the drought forced infected wildlife into more populated areas in search of food and water.
“Starting in December last year, we began fielding calls about skunks that were behaving badly. These animals are generally nocturnal and rarely interact with humans, but reports indicated these skunks were acting aggressively and there were reports of skunks that had bitten pets,” said Dr. Megin Nichols, assistant state public health veterinarian in Santa Fe.
“Since that time we have tested both skunks and fox with positive results and have launched a comprehensive campaign to control what potentially could become a larger problem.”
Nichols confirms that officials believe the drought has contributed to the current outbreak and warns that warmer weather in the coming spring and summer could serve to boost the spread of the virus.
“The potential is there for increased rabies activity in the summer, and also of concern is the upcoming breeding season when we could potentially see greater expansion of the outbreak,” Nichols adds.
While livestock is at risk, so far animals testing positive for rabies has been mostly limited to domestic dogs. State and county health officials have launched an aggressive campaign to encourage rabies vaccinations of pets in Carlsbad and will continue efforts to educate the public on the risks. Of particular concern are children who interact more regularly with pets.
“Concerning livestock, including horse and cattle, we are recommending vaccinations of animals that will be exposed to human contact, such as show animals and 4-H, FFA animals traveling to and from exhibitions,” Nichols says.
Rabies is of greater concern for domestic pet owners, but infection among farm animals is not uncommon. In Western North Carolina, an area troubled by rabies outbreaks, officials say cattle are one of the most common domestic animals to contract the deadly virus, putting cattle producers at an increased risk.
Rabies is not limited to any one particular area. The Southwest, because of dry, hot conditions, is generally a hotspot for outbreaks though. In Texas alone last year, some 1,018 cases of confirmed rabies were recorded. This year 73 cases have been confirmed in Texas so far.
In a report in Transylvania County, N.C., in the year 2000, only cats exceeded cattle in the incidence of rabies cases in domestic animals. The report, prepared by Dr. William Dee Whittier, Extension veterinarian, cattle, Virginia-Maryland Regional College of Veterinary Medicine, says a large amount of effort goes into keeping pet owners safe from rabies through vaccination programs and educational efforts, but warns that those who routinely handle cattle are less often reminded of the threat of the disease which is almost always fatal.
“Cattle most often become infected with rabies when they come in contact with infected raccoons, skunks or foxes. Cattle’s curious nature puts them especially at risk when they investigate an animal which is acting strangely in their area [and] rabid animals are prone to bitelivestock on the nose or extremities,” the report indicates.
Because these wildlife species are well adapted to areas where cattle are kept the threat of becoming infected is always present. Cattle in barns or other enclosures are not spared the risk of rabies since infected wildlife commonly frequent cattle housing.
Rabies symptoms, behavior
“Symptoms of rabies in cattle vary considerably. The slobbering, aggressive cow is only one way that the disease presents itself. Initial signs of the disease may be quite mild with cattle appearing depressed, not eating and isolating themselves. As the disease progresses function of some body parts decreases. This might result in the inability to swallow so that saliva is drooled, but it might also be weakness in a leg or legs or a drooping ear or head,” the report indicates.
Animal behavior may also be varied. A few rabid animals are aggressive but many are sleepy and constant bellowing or straining is also seen. Most animals affected by the disease die within a week from the time that signs are first seen.
Because the signs of rabies are not always certain, animals that don’t fit a pattern of typical disease should be examined by a veterinarian. This is especially true if any signs of the disease suggest that the brain is involved in the disease. Animals that die with suspicious signs should be taken to the diagnostic lab and the lab should be made aware of a rabies suspicion.
Officials say anyone who suspects that they have been exposed to rabies through association with rabid cattle or any other animal should seek medical attention immediately. Preventive vaccination is effective if initiated soon after exposure. Once the disease has incubated, the outcome is nearly always fatal.
Health officials say prevention of rabies in cattle is not an easy task. Vaccines are available but are so expensive that their routine use in cattle herds is not recommended unless a farm has a very high threat of the disease.
Wildlife control should be a concern for all cattle operations for rabies prevention and for other health and safety reasons. In some cases, hunting and trapping should be employed, and in all cases attempts should be made to secure feeds that would attract wildlife likely to be rabid.
While rabies is not a high incidence disease in cattle operations, the threat to the health of farm personnel is so great that a constant vigilance is required and should be practiced by all cattle workers.
The Centers for Disease Control and Prevention (CDC) offers this guidance to veterinarians dealing with rabies-infected livestock:
For client animals with up-to-date rabies vaccinations:
Livestock exposed to a rabid animal and currently vaccinated with a USDA-approved vaccine for that species should be revaccinated immediately and observed for 45 days.
If an exposed animal is to be slaughtered for consumption, it should be done immediately after exposure. Barrier precautions should be used by persons handling the animal, and all tissues should be cooked thoroughly.
Historically, federal guidelines for meat inspectors have required that any animal known to have been exposed to rabies within eight months be rejected for slaughter. USDA Food and Inspection Service meat inspectors should be notified if such exposures occur in food animals before slaughter.
Multiple rabid animals in a herd or herbivore-to-herbivore transmission is uncommon. Therefore, restricting the rest of the herd if a single animal has been exposed to rabies usually isn’t necessary.
For client animals without up-to-date rabies vaccinations:
Unvaccinated livestock should be euthanized immediately. If the animal is not euthanized, the animal should be closely observed for six months. Any illness while under observation should be reported immediately to the local health department.
If signs suggestive of rabies develop, euthanize the animal and ship the head for testing. Multiple cases in a herd or herbivore-to-herbivore transmission is uncommon. Therefore, restricting the rest of the herd if a single animal has been exposed to or infected by rabies usually isn’t necessary.
For more information: http://www.cdc.gov/rabies/specific_groups/veterinarians/potential_exposure.html