Logan highlights zoonotic diseases at WESTI Ag Days
Worland – In a presentation on diseases that can be transferred between animals and humans at the 2013 WESTI Ag Days, Wyoming State Veterinarian Jim Logan warned producers to be careful in treating and interacting with animals.
“A zoonotic disease is an infectious disease that can be spread from animals to humans and vice versa,” explained Logan at the Feb. 5 event. “The diseases I talk about today are those that we have had in Wyoming.”
The Wyoming Department of Health lists 96 reportable diseases, and of those, 60 could also be transmitted from animals to humans. The Wyoming Livestock Board also lists over 100 reportable diseases.
“Many of the diseases that can be transmitted are ones that producers will recognize,” Logan added.
“Plague is one of the diseases that many people thought was a thing of the dark ages,” said Logan, “but plague is still alive and well.”
He noted that there are cases in the state fairly frequently, and animals, such as cats and prairie dogs, are big carriers. In the case of cats, Logan cautioned people that if cats have an abscess, it may be caused by plague picked up from a flea or prairie dog.
“If people get plague, it can be potentially fatal,” he said. “People may not hear about cases of plague because of confidentiality.”
Plague can affect a variety of species, including cattle, and is transmitted by fleabites, direct contact or by aerosol or respiratory secretions.
“It occurs as bubonic plague, septicemic plague – which affects all organ systems – and pneumonic plague, which is the most serious when it gets into the lungs,” he explained.
Logan cautioned producers that the disease can be very serious.
Another disease that is widespread across the state is rabies.
“Rabies is a chronic problem,” said Logan. “Every year, we find rabies in Wyoming. So far in recent years nothing has been transmitted to people, but there have been a lot of species affected.”
The primary reservoir species are bats and skunks, and Logan said that skunks are the biggest wildlife reservoirs in Wyoming.
“If you see a skunk or any animal acting strange or aggressive or out at a strange time of day or year, there is a possibility that it has rabies, and you should take precautions,” Logan said. “Any change in behavior from normal means there is a possibility it could have rabies.”
He added that if the animal is a wild animal, people should call the Wyoming Game and Fish Department. Domestic animals, such as cats, dogs and livestock, should be confined until a veterinarian can be reached.
“Confine animals with precaution because they can bite and transmit the disease to you,” he explained, adding that producers want to be careful in getting rid of potentially rabid animals to preserve diagnostic capabilities. “The only method of testing for rabies is to look for Negri bodies in the brain. If the brain of the animal is destroyed, you have no diagnosis.”
“Rabies comes and goes,” Logan added. “In 2011, we saw more of it, and that might be because people are more aware of it.”
The rabies virus is primarily spread through the saliva of an infected animal, but can also be spread through blood of infected animals.
He also noted that rabies is a very serious situation and, in livestock, it may be mistaken for animals with something stuck in their mouths or throat.
“Human exposure can occur when a livestock species, such as a horse or cow, starts showing signs of rabies. The signs include excessive salivation, inability to swallow and going off feed,” he said. “The first thing that a farmer or rancher is going to think is that the animal has something stuck in its mouth and often reach in to remove it.”
Human exposure is not uncommon. Logan notes that veterinarians and vet students are at high risk for exposure to rabies and other zoonotic diseases.
Though humans and animals can be vaccinated, Logan noted that no vaccination is 100 percent effective.
“Even though an animal has been vaccinated, it can still get rabies,” he cautioned.
Another serious zoonotic disease that is potentially fatal to humans is Q Fever.
“We don’t have any current human cases in Wyoming, but we do have one known case in a flock of sheep in Albany county,” Logan explained. “Chances are that Q Fever is more widespread across the county, but there isn’t a required test for Q Fever.”
Logan also noted that it is very similar to several other diseases, meaning it is sometimes mistaken for those and not diagnosed.
“This disease is very, very serious,” he continued. “People have nearly died in Wyoming from Q Fever.”
With a big outbreak in 2001, Logan noted that it hadn’t been reported in Wyoming before that.
“The symptoms in humans include headaches, respiratory problems and a lot of fever,” he explained. “It can last for quite a while.”
“We do not have tuberculosis (Tb) in Wyoming as far as we know, but Tb is a huge problem in Mexico,” Logan said. “Most of Mexico’s states still have tuberculosis, and we import a lot of Mexican cattle for feeding or recreation. The disease is still present in the U.S. in dairy and recreational cattle.”
While imported cattle require testing for tuberculosis before entering the U.S., the incubation period for the disease is very slow, so it may take months or even years to show up on a Tb test.
“A negative test doesn’t always mean that the animal is clean,” Logan explained.
“In spite of an eradication program in the U.S. cattle industry, the disease continues to be a problem,” Logan continued. “In my early years of practice, the USDA thought they had about conquered it, but it has made a resurgence in the U.S. and is still a big concern to the cattle industry and public health.”
Tuberculosis is spread primarily by aerosol and affects the respiratory system, as well as other systems of the body.
“It is chronic and progresses over a number of years,” he said. “The testing programs don’t give me a great deal of comfort because the infections don’t show up until years after cattle have been exposed.”
Other diseases that can be transmitted between animals and humans include tularemia, toxoplasmosis, West Nile Virus, brucellosis, salmonella, Johne’s disease, anthrax, campylobacter, also know as vibrio, and leptospirosis.