Mycoplasma ovipneumoniae (M. ovi) in Alaska Wildlife: Answers to Frequently Asked Questions
What is M. ovi?
M. ovi is a shorthand name for Mycoplasma ovipneumoniae (pronounced "My-koh-plaz-ma oh-vee nu-moh-nee-ay"). M. ovi is a bacterium that can lead to respiratory disease such as pneumonia in wild and domestic sheep and goats. M. ovi does not affect humans.
Until recently, little was known about the status or presence of M. ovi and other bacteria of the Mycoplasma genus in Alaska. Mycoplasmas are simple organisms lacking cell walls; more than 100 known species exist but there are likely many more that are unknown. Mycoplasma species are divided further into various genetic types.
Has M. ovi been found in Alaska's wildlife?
Surveillance for bacterial respiratory pathogens from hunter harvest and research samples identified bacterial DNA of M. ovi along with other mycoplasma species with close genetic relationships to M. ovi in healthy wildlife populations in Alaska. Of the areas surveyed, on multiple tests at multiple labs we have had positive detections of M. ovi presence in populations of Dall's sheep in the eastern Alaska Range, Talkeetna Mountains, and Wrangell Mountains, as well as Fortymile and Nelchina caribou, and we have had M. ovi detections in other areas and species on at least one test. Importantly, there may not be cross immunity for different genetic types so the presence of M. ovi in wildlife doesn't mean they are 'safe' or immune to 'new' types. At this time, ADF&G does not believe that wildlife populations are in danger due to M. ovi genetic types currently in Alaska's wildlife.
Are Alaska's wildlife populations in danger from (or due to) M. ovi?
The presence of M. ovi does not mean animals are diseased or will become sick. In Alaska, M. ovi has been detected on nasal swab samples from multiple healthy Dall's sheep, as well as healthy mountain goats, caribou, and moose. In 2019 there have been a few wildlife mortalities due to respiratory and other diseases, which is well within the normal levels of disease related mortalities that ADF&G sees from year to year. In only one of the 2019 disease related mortalities was the presence of M. ovi detected. Importantly, there may not be cross immunity for different genetic types of M. ovi, so the presence of M. ovi in wildlife does not mean they are 'safe' or immune to 'new' M. ovi genetic types.
How does M. ovi affect sheep?
- In wild sheep in several western states and British Columbia, M. ovi has been identified as a pathogen in bighorn sheep pneumonia outbreaks. These M. ovi-related outbreaks have resulted in sporadic and, in some places, large-scale morbidity and mortality events in bighorn sheep. Some of these have resulted in subpopulation-level events with mortalities of 70 to 90 percent. M. ovi has also been detected in healthy populations of bighorn sheep in several western states.
- M. ovi paralyzes cilia (cilia are hair-like structures that help keep the lungs clear of mucus, dust, and pathogens) in the airways and prevents them from moving out pneumonia-causing bacteria that are inhaled into the lungs. This combination of multiple bacteria can cause respiratory disease, particularly when the animal is affected by other factors such as nutritional or environmental stress.
- In cases where M. ovi results in pneumonia in domestic sheep, lambs usually are more severely affected. Some populations of infected bighorn sheep that have survived M. ovi-related disease events have shown poor lamb recruitment and low or stagnant population growth rates in years following a pneumonia outbreak.
- Domestic sheep and bighorn sheep can be clinically healthy carriers of M. ovi. This means some sheep carry M. ovi bacteria in their nasal passages and exhibit no ill effects. These sheep may transmit M. ovi to other animals and over time increase the number exposed and at risk of infection.
Has M. ovi been verified in domestic animals in Alaska?
The Office of the State Veterinarian reports that the estimated population of domestic sheep and goats in Alaska is about 1,500 animals. So far, over 656 animals have been tested and M. ovi has been detected on nasal swabs in about four percent of those animals, spread across about a quarter of the flocks tested.
Did domestic livestock bring M. ovi to Alaska?
This is unknown. Records indicate that thousands of domestic sheep were brought to Alaska in the late 1800s and early 1900s. All animals, humans included, have their own suite of microorganisms including parasites that are 'normal' and rarely causes disease in the natural host (host in which the microorganism has evolved with time). Because there are several Old World (i.e., outside of Americas) domestic animal adapted parasites and microorganisms that have been found to occur and be pathogenic in Alaska's wildlife, it seems plausible that some of these originated from livestock introductions in the gold rush and homesteading eras. Over time, wildlife populations appear to have adjusted to many of these potential pathogens and parasites, so we only see disease when there are other stressors impacting their resistance.
While it is possible that M. ovi was introduced to Alaska by domestic livestock, that is uncertain and may have happened long ago (e.g., when domestic sheep were first brought to Alaska). M. ovi has been detected in archived samples as far back as available, including from a Dall's sheep that died in 2004 and a caribou that was sampled in 2012. Also, of note are positive M. ovi detections in wildlife populations in remote areas of the state with no history of domestic livestock presence (e.g., northern Brooks Range).
The current populations of domestic sheep and goats in Alaska are relatively small and generally confined on farms. Still, there is concern, and we must be vigilant to prevent the transmission of additional, non-endemic species or strains of potential pathogens, including M. ovi, to wild and domestic animals in Alaska. Our collaborative studies and cooperative work with the Department of Environmental Conservation (DEC), especially the Office of the State Veterinarian, are intended to address the risks of wildlife/livestock interactions.
How long have we known M. ovi to be present in domestic animals in Alaska?
In 2017, a respiratory pathogen surveillance project of domestic sheep and goats was started. This voluntary project was the first concerted effort that included testing specifically for M. ovi from sheep and goat farms across the state. Since it only occasionally causes clinical disease in domestic sheep and goats, the pathogen was not regularly included in diagnostic testing in cases of respiratory illness in livestock. M. ovi is not a reportable pathogen (which requires notification to DEC), so no surveillance was being done previously in domestic animals.
Is testing currently being done for M. ovi in domestic animals in Alaska?
Voluntary surveillance testing is available from DEC on request of livestock owners, although the original study is in the data analysis and writing phase. In addition, samples are being collected by Cooperative Extension Service and the Future Farmers of America (FFA), Additionally, the USDA National Animal Health Monitoring System (NAHMS) Goat Study will be sampling between 10 and 20 goat farms for a number of pathogens, including M. ovi.
Where can I learn more about M. ovi in Alaska's domestic sheep and goats?
More information can be found on the Department of Environmental Conservation's webpage at http://dec.alaska.gov/eh/vet/movi.aspx
What testing is done and how is M. ovi detected?
Blood and nasal samples are collected from live captured animals, and nasal samples are collected from hunter harvested animals. Serum, extracted from the blood samples collected from sheep and goats, is tested for antibodies to M. ovi. If antibodies are present, then it indicates the animal has been exposed to this bacteria at some point in its life. However, antibodies alone do not necessarily indicate that M. ovi is currently present. The nasal samples are collected by inserting a swab into the nasal cavity and are analyzed using polymerase chain reaction (PCR) tests that detect the actual genetic material of the Mycoplasma bacteria. There are many species of Mycoplasma that can be found in animals, only some of which pose a potential threat of causing disease.
How long has M. ovi been present in Alaska's wildlife?
The oldest archived sample with a positive M. ovi detection was a Dall's sheep lamb that died of pneumonia in 2004 and was tested in 2019. The earliest detection in caribou was from nasal swabs of live captured caribou sampled in 2012 and archived until tested in 2018. However, there are very few archived samples prior to 2012 available to be analyzed by the new PCR methods. Routine surveillance prior to 2009 was only on Dall's sheep and utilized the only available tests at the time for detecting M. ovi which were different tests and not as sensitive or specific as newer methods. Furthermore, M. ovi was not known to be the primary pathogen of concern in wild sheep pneumonias and was not a primary target of surveillance efforts.
How is M. ovi transmitted in animals?
M. ovi is a bacterium inhabiting the upper respiratory tract and is spread when animals exhale, cough, and sneeze the bacteria out in tiny particles that can remain suspended in the air. It is most commonly spread by direct contact, and possibly by exposure to contaminated feed or equipment. However, current knowledge indicates that M. ovi is not environmentally stable (it dies in the environment) and therefore requires a direct source for transmission. It may cause disease in the lower respiratory tract (lungs) when other bacteria are present and the immune defenses are overwhelmed. Transmission between animals and presence of M. ovi in the nasal passages does not mean 'infection' occurred, or that detectable antibodies will be produced, or pneumonia will occur. Only when both the bacteria and lung lesions consistent with bacterial pneumonia are present can a diagnosis of disease due to M. ovi be confirmed.
What can be done on a statewide level to prevent the spread of M. ovi in Alaska wildlife?
The best way to prevent the spread of pathogens (viruses, bacteria, parasites) from livestock to wildlife is to follow the general principal of complete separation of livestock from wildlife. This means avoiding livestock/wildlife interactions such as comingling or any means of contact including indirect contact via environmental contamination or vectors. To reduce the risk of the spread of pathogens that can cause disease, Alaska law prohibits the use of domestic goats and sheep as pack animals when hunting Dall's sheep, mountain goat, or muskoxen. Additionally, we encourage the public to voluntarily refrain from using pack goats for recreational activities in the backcountry.
What is ADF&G doing about this?
We are continuing to monitor the health and productivity of wildlife populations, working with investigators to refine detection methods, and investigating the potential significance of the identified mycoplasma species and other potential pathogens on wildlife health in Alaska.
This includes: (1) taking samples from select hunter harvested animals, (2) investigating dead and/or sick animals, (3) sampling animals handled during management or research projects, (4) establishing multi-year intensive monitoring studies of specific wild sheep and goat populations to assess the impact of respiratory pathogens including M. ovi, (5) conducting research to improve future surveillance efforts, and (6) coordinating with DEC on their efforts to screen and monitor domestic sheep and goats.
How can hunters help?
Report any observation of abnormal behavior, sick or unexpectedly dead wildlife to an ADF&G office or via the website link.
Participate in hunter harvest sampling —
During the 2020 hunting season, ADF&G are requesting hunters assist us in obtaining samples primarily from mountain goats, Dall's sheep that were coughing or had lung lesions. We would also like to sample sheep from the few areas we have not yet had adequate sampling, Western Brooks, Western Alaska, Kenai and Ogilvie Mountain ranges. Whenever possible, please bring heads with intact nasal mucosa/lung samples from animals harvested in those areas to a listed ADF&G office within SEVEN days of harvest for sampling during sealing for sheep and when bringing in goat horns to be measured.
- Dall's Sheep: Fairbanks, Anchorage, Palmer, Tok, Delta Junction, and Glennallen.
- Mountain goats: Douglas, Homer, Ketchikan and Sitka (or Anchorage).
- October 17, 2019 M. ovi update (PDF 879 kB)
- Results of Nasal Swab Samples from Hunter-harvested Sheep (PDF 698 kB)
- Preliminary Mycoplasma ovipneumoniae (M. ovi) testing results in wildlife, Sept. 23, 2020 (PDF 147 kB)
- Interpreting MLST data for strain-typing of Mycoplasma ovipneumoniae sequence segments (PDF 182 kB)