The blood disease anaplasmosis could surface in cattle herds this fall, and producers should keep a watchful eye on animals, says Purdue veterinarian and clinical assistant professor of veterinary medicine Bethany Funnell.
The disease, which causes severe and potentially fatal anemia in cattle but poses no threat to humans, is caused by the parasites Anaplasma marginale and Anaplasma centrale.
"If you have, or suspect anaplasmosis, work closely with your herd veterinarian to develop effective treatment and control programs," Funnell said. "Death of an adult is often the first sign noticed in a herd infection."
Symptoms in cattle include weight loss, loss of appetite, high fever, dehydration, constipation, pale mucous membranes inside eyelid and vulva, jaundice, abortion in pregnant cows and aggressive behavior. The disease is more common among middle-aged animals, with most fatal cases occurring between 6 and 8 years old.
Anaplasmosis in cattle is spread by parasites such as biting flies and wood ticks. Wet weather in the spring may have created ideal breeding conditions for the insects that carry the disease.
Herds may also become infected by de-horning, ear-tagging, castration, injection and other equipment that has not been disinfected between uses on different cows.
"Data shows that a syringe used on an infected cow could infect six out of the next 10 animals injected using the same syringe," said Ron Lemenager, a Purdue Extension beef specialist.
The disease is found in both beef and dairy herds but is less common in dairy herds.
Early treatment needed
Early treatment of the disease is key to keeping cattle alive. Funnell recommends that producers in high and moderate infection areas consider vaccinating young cattle against anaplasmosis because symptoms are often not seen in cattle younger than a year old.
Funnell said clearing infection requires long-term antibiotic therapy, and producers should consult their herd veterinarians to decide on an appropriate course.
Time from exposure to clinical signs of anaplasmosis in cattle is 3-6 weeks, and some cattle may become asymptomatic carriers, meaning they could carry the disease without showing any signs of it.
"Carrier" animals are less vulnerable to a full-blown infection, so producers might want to consider exposing all of their cattle if the infection rate in the area is high, in effect vaccinating the animals against a serious infection.
If the infection rate in a region is moderate to low, it could be possible to clear the infection from a herd without exposing the animals.
In areas where infection is high, Funnell said producers should consult with their veterinarians as soon as possible to plan an appropriate course of action.
She noted that transporting cattle carrying anaplasmosis might be difficult because some state animal regulations may require a negative test for the infection before transport. To find out if an area is highly infected, Funnell suggests producers consult local food animal veterinarians and regional Extension educators.
Lemenager said that handling animals infected with anaplasmosis could present challenges because of their weakened systems.
"If you're herding these cattle, you're going to need to bring them up easy, because they don't have enough oxygen, being anemic," he said. "If they get too excited, these cows could die."