Bovine Tuberculosis Detected in Michigan Dairy

Tue, 24 Feb 2026 19:18:19 GMT

The Michigan Department of Agriculture and Rural Development (MDARD) has confirmed a case of bovine tuberculosis (TB) in a dairy herd in Charlevoix County, located west of Michigan’s Modified Accredited Zone (MAZ), where the disease is known to be present in the state’s white-tailed deer population.

(Michigan Department of Agriculture and Rural Development)

According to state officials, the detection followed identification of bovine TB in an adult cow at a USDA Food Safety Inspection Service-inspected processing plant. Through animal traceability efforts, officials traced the animal back to its herd of origin. Subsequent testing of the herd identified additional bovine TB cases.

“This latest detection of bovine TB highlights two important realities: how challenging the disease is to address; and why it is so crucial to use all of our tools for detection to swiftly identify cases and take actions to limit disease spread,” say Nora Wineland, state veterinarian for Michigan. “While finding a newly affected herd is never ideal, this case demonstrates our systems for detection and traceability are working, allowing us to quickly implement measures to protect animal health and public health in Michigan.”

MDARD reports an epidemiological investigation is already underway to determine whether additional cases may be linked to the affected herd. There are currently two TB zones within the state: a four-county area in northern lower Michigan called the Modified Accredited Zone, and the remainder of the state’s 83 counties is referred to as the Accredited Free Zone.

This is Michigan’s second confirmed bovine TB case in the past 13 months. The previous case was identified in a beef herd in Alcona County, located within the state’s Modified Accredited Zone, in January 2025. With this latest detection, a total of 84 cattle herds have been confirmed with bovine TB in Michigan since 1998.

What is Bovine Tuberculosis?

According to USDA’s Animal and Plant Health Inspection Service (APHIS), bovine tuberculosis is a chronic bacterial disease that can infect all mammals, including humans. It is caused by the bacterium Mycobacterium bovis and spreads through both direct contact between infected and uninfected animals and indirect exposure, such as contaminated feed, water or the environment.

The disease progresses slowly, often developing over several years. Infection typically begins in the lymph nodes before advancing to the lungs and chest cavity, where it can cause serious lesions.

While cattle are the primary host, the disease can also be present in white-tailed deer and elk, as well as bison, goats and certain carnivores, including coyotes.

The Symptoms

Unfortunately, infected cattle are typically asymptomatic. Detection usually occurs during live animal skin testing or, more commonly, at slaughter through our national slaughter surveillance program, according to USDA. If cattle or bison show clinical signs of tuberculosis, the disease has advanced to affect multiple organ systems, which is rare.

Can it be Prevented?

Bovine TB most often spreads through close contact, especially nose-to-nose interaction between animals, or when cattle consume feed or water that’s been contaminated. In most cases, herds become infected one of two ways: by bringing in an infected animal or through exposure to infected wildlife.

While the prevalence of tuberculosis in cattle is extremely low in the U.S., with an estimated prevalence of 7 per 1 million cattle screened, it can occur. Producers should work alongside their veterinarian to help create a biosecurity plan.

How is it Identified?

According to APHIS, the primary source of tuberculosis surveillance is carcass inspection at all federal and state inspected slaughter establishments. The other main sources of tuberculosis detection are testing animals before interstate movement and during disease investigations. Live animal testing is performed with a screening test. If positive, the regulatory veterinarian will conduct a confirmatory test.

Can it be Treated?

Unfortunately, tuberculosis in livestock is not a treatable disease. When health officials find tuberculosis in a herd, it is managed by either depopulating the herd or by testing and removing reactor animals.

Beef Producers Be Aware: Dangerous Asian Longhorned Tick Continues Migrating West

Wed, 18 Jun 2025 13:24:33 GMT

The Asian Longhorned Tick (ALHT) poses a serious threat to cattle health. ALHTs carry Theileria, which is a protozoan parasite that infects red and white blood cells. It can lead to anemia and, in some cases, death.

ALHTs are native to eastern Asia, eastern China, Japan, the Russian Far East and Korea but were introduced to Australia, New Zealand and western Pacific Islands. In other countries, it can also be called a bush tick, cattle tick or scrub tick.

In the U.S., ALHT was first detected in New Jersey in 2017. Since then, it has spread to more than 20 states with recent confirmations in Illinois , Michigan and Iowa .

According to USDA’s Animal and Plant Health Inspection Service (APHIS) ALHTs are known to carry pathogens, which can cause disease and may also cause distress to the host from their feeding in large numbers. For example, a dairy cow may have a 25% decrease in milk production after becoming a host.

A female can reproduce without a mate and lay up to 2,000 eggs at a time. This can cause great stress on a heavily infested animal and result in reduced growth and production. A severe infestation can kill the animal from excessive blood loss.

Asian longhorned tick life stages and relative actual size.

(Photos of unfed ticks by Centers for Disease Control. Photos of engorged ticks by Jim Occi, Rutgers, Center for Vector Biology.)

What does it look like?

Unfed ALHTs range from a light reddish-tan to a dark red with brown, dark markings. While the adult female grows to the size of a pea when full of blood, other stages of the tick are very small — about the size of a sesame seed.

Adult females are a grey-green with yellowish markings. Male ticks are rare.

APHIS reports it only takes a single tick to create a population in a new location.

The above photos are of a AHLT engorged (on the left) and an adult AHLT not engorged.

(New Jersey Department of Agriculture)

ALHTs need warm-blooded hosts to feed and survive. They have been found on various species of domestic animals — such as sheep, goats, dogs, cats, horses, cattle and chickens — and wildlife. The tick has also been found on people.

What are the health risks?

APHIS says ALHTs are not known to carry Lyme disease, but they can cause tickborne diseases affecting humans and animals such as:

Rocky Mountain spotted fever
Heartland virus
Powassan virus

APHIS says those diseases have not been confirmed outside of a laboratory setting in the U.S. In addition, U.S. ALHT populations can transmit U.S. Theileria orientalis Ikeda strain (Cattle theileriosis) in the laboratory.

In an Iowa State University release , Grant Dewell, Extension beef veterinarian and associate professor, says cattle affected by Theileriosis will show signs of lethargy, anemia and difficulty breathing. They may develop ventral edema, exercise intolerance, jaundice and abortions.

“Although signs of Theileriosis are similar to anaplasmosis, younger animals and calves often display more severe signs compared to mature cows and bulls,” he says. “Due to anemia from both tick infestation and Theileria, the risk of death can be elevated. If cattle producers suspect either Theileria or ALHT, have a veterinarian collect appropriate samples and submit them to a veterinary diagnostic lab.”

According to an Oklahoma State University press release , under laboratory conditions ALHT is a competent vector of numerous pathogens that can cause disease in humans, including Rickettsia rickettsii (Rocky Mountain Spotted Fever), Heartland Virus and Powassan Virus.

In “ Clinical Infectious Diseases, ” Bobbi Pritt, MD, MSC, with the division of clinical microbiology at the Mayo Clinic in Rochester, Minn., reported a human bite that occurred in New York in 2019. She says though the report of a human bite isn’t surprising, it proves the invasive longhorned tick continues to bite hosts in its newest location.

“This is extremely worrisome for several reasons,” she writes. “One reason is Asian longhorned ticks can carry several important human pathogens, including the potentially fatal severe fever with thrombocytopenia syndrome (SFTS) virus and Rickettsia japonica, which cases Japanese spotted fever. While these pathogens have yet to be found in the United States, there is a risk of their future introduction.”

Also, Pritt says several other human pathogens have been detected in the ticks, but it’s not clear if the ALHT species are able to transmit them to humans. They include Anaplasma, Ehrlichia, Rickettsia, and Borrelia species. Lyme disease is caused by Borrelia burgdorferi bacteria.

She warns the organisms are present in states where ALHTs have been found and that it’s possible the tick — known to be an aggressive biter— might be able to transmit Heartland virus given its close relationship to SFTS virus.

How to Tackle Ticks

According to APHIS, various strategies effectively mitigate tick populations on hosts and in the environment.

Regular tick treatments should be effective against ALHTs. Consult your veterinarian or agriculture extension agent about which products to use.
Check your livestock for ticks regularly.
Safely remove ticks from people and pets as quickly as possible. If you think you’ve found an ALHT, seal it in a zip-top bag and give it to your veterinarian for identification.
Habitat modifications can help prevent ticks on feedlots and pastures. This may include mowing grass, removing trees, reducing shade by thinning trees, understory removal and placing mulch barriers.
Apply acaricide using label instructions to tick habitats, such as woodland edges and grassy patches, during times when ticks are most actively seeking hosts. Although it varies by year, ALHTs are generally active from March to November. Consult your state and local regulations for approved acaricides.

“Cattle producers should aggressively control external parasites this summer,” Dewell summarizes. “Insecticide ear tags alone are not enough to control ticks. Consider incorporating a back rubber or regularly applying a pour-on during the summer. Pyrethroid-based products are also available that include a tick control label. If an increase in tick infestations is observed, an avermectin pour-on may be the best intervention.”

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