What is the Difference Between Tuberculosis, Paratuberculosis and Mycoplasmosis in Deer?

By Nelda A. Rivera, Nohra Mateus-Pinilla

Learning to differentiate diseases affecting white-tailed deer (WTD) in Illinois can be challenging, as many pathogens — including bacteria, viruses, protozoa and prions — could cause disease. Here, we focus on three bacterial diseases affecting deer that can be confused. The disease names can be similar, and the signs of disease observed by people and symptoms presented by animals can be identical. That is the case of Mycobacterium avium (subspecies paratuberculosis), Mycobacterium bovis and Mycoplasma bovis (causing Paratuberculosis, Tuberculosis and Mycoplasmosis, respectively). We will summarize the differences and similarities between these diseases.

Where do we find these bacteria? Who can be affected?

Mycobacterium bovis and Mycoplasma bovis are abbreviated as M. bovis, but although both bacteria are given the surname “bovis,” they differ in structure, diagnosis and treatment. Both Mycobacterium bovis (bTB bacteria) and Mycoplasma bovis occur globally in members of the Bovidae family, such as cattle, bison, elk and deer. However, the primary domestic and wild reservoir hosts capable of transmitting bTB to other species are cattle and white-tailed deer (respectively)^1,2. Ultimately, Mycobacterium bovis is zoonotic (spreads from animals to humans) and may cause Tuberculosis (bTB) in humans, while Mycoplasma bovis does not affect humans.

Mycobacterium avium (M. paratuberculosis) is a foodborne pathogen found in soil and watercourses worldwide. It affects predominantly cattle and sheep and may cause disease in humans (especially in susceptible populations such as children and the immune-compromised)³ and other mammals including deer⁴. However, infected ruminants act as reservoir hosts as they can shed the bacteria in feces and milk, contaminating water, soil and dust.

The exposure to these bacteria varies depending on the host (Figure 1). For instance, bovine tuberculosis (bTB) transmission can result from direct nose-to-nose contact between domestic animals. However, transmission between domestic animals and wildlife (e.g., deer, coyotes, wild boars, raccoons and opossums) may occur after ingesting food and water contaminated with bTB. For humans, the exposure route at the human-cattle interface is aerosol, ingestion (e.g., unpasteurized milk), or through broken skin (Figure 1). Human exposure at the human-wildlife interface is mostly by ingesting contaminated meat and through contact with the bacteria with broken skin (Figure 1).

A graphic describing how bovine tuberculosis is spread between cattle, humans, and wildlife. On the left side are silhouettes of cows, sheep goats, and pigs. On the right side are silhouettes of elk, deer, raccoons, mice, foxes, and a wild boar. In between the silhouettes are two people at the top and plants at the bottom. — Figure 1. Risk of bovine tuberculosis (bTB) transmission/spread at the cattle-human-wildlife interface^5,6. Domestic and wild reservoir hosts (***black***), potential reservoir hosts (***dark gray***), and final hosts (***light gray***) can interact with each other and through the environment. ***Dash line*** show the potential indirect routes of infection between wildlife and humans.

How do Mycobacterium bovis and Mycoplasma bovis spread to white-tailed deer?

Mycobacterium bovis and Mycoplasma bovis have similar transmission routes and clinical signs, such as respiratory disease, mastitis (swelling in the breast) and weight loss. Both are primarily transmitted via inhalation of aerosols from infected animals. Direct cattle-to-cattle contact is the primary transmission mechanism for Mycobacterium bovis in farm animals. Still, indirect transmission occurs through water, contaminated feed and equipment, and people/items moving the bacteria⁷. Wildlife such as WTD can acquire the bacteria indirectly following exposure to cattle-contaminated soil, water, or feed, as direct transmission between cattle and wild WTD is rare. However, direct contact among wild WTD may be more frequent and, therefore, a more significant route of infection^1,2.

The symptoms depend on the animal species involved and the mucous membranes affected (e.g., membranes surrounding the respiratory and intestinal tract, genital tract and mammary glands). For example, when Mycoplasma bovis infects the respiratory tract, it causes bronchopneumonia, which can be severe and even fatal in some cases, it can induce coughing, nasal discharge, fever, and difficulty breathing. Infected domestic and wild animals, including WTD, cattle, and bison may show weakness, lethargy and weight loss. Other symptoms, such as mastitis and arthritis, have been documented in cattle and bison. Unfortunately, these symptoms are like other respiratory infections, making it challenging to diagnose without laboratory testing.

Bovine tuberculosis (bTB) is commonly found in North America in cattle/bison and domestic/wild cervid species such WTD, elk and moose (Table 1)^1,2. So far, reports of wild WTD infected with bTB in North America are limited to Indiana, Michigan, Minnesota, New York and Ontario¹.

Table 1. Reported wildlife reservoirs of bovine tuberculosis or bTB (caused by Mycobacterium bovis) in the United States and ^*Canada⁷.

A table indicating reported wildlife reservoirs of bovine tuberculosis in the United States and Canada. Different animals that hold on to the disease are elk, white-tailed deer, mule deer, axis deer, moose, bison, and wood bison. — References: O’Brien et al. 2006; Rhyan et al. 1995; Schmitt et al. 1997; Sawa et al. 1974; Wobeser 2009; Kaneene et al. 2010.

Is Paratuberculosis the same as tuberculosis in deer?

The answer is NO. While a Mycobacterium causes both diseases, bovine tuberculosis (bTB) is caused by Mycobacterium bovis (a member of the Mycobacterium tuberculosis complex or MTBC), and Paratuberculosis is caused by a member of the Mycobacterium avium complex (MAC) which is unrelated to MTBC and does NOT cause tuberculosis.

There is no bovine tuberculosis (bTB) in Illinois’ WTD. However, M. paratuberculosis has been detected in Illinois wild WTD. As shown in Figure 2, the chest cavity’s lymph nodes, lungs, and inner ribcage surface areas can have small white lesions similar to bTB. Therefore, diagnostic testing is required to rule out bTB. While humans are generally resistant to M. paratuberculosis, they can get infected.

Two images of the liver of a two year old deer. The image to the left is an overall view and the image to the right is a close-up of the tissue. — Figure 2. Liver of a 2-year-old deer with countless white to tan, solid, disseminated, mycobacterial granulomas (*Mycobacterium avium* subspecies *paratubereculosis*). Pictures courtesy of Bryan Eubanks.

For managers and hunters

Infectious diseases such as bovine tuberculosis (bTB) and paratuberculosis in WTD can impact hunters and wildlife management programs, as infected animals are not fit for human consumption and may spread the disease to other wildlife or domestic livestock. Therefore, only harvest animals that appear healthy and look for potential signs of disease (e.g., multiple small gritty lumps in the lungs, lymph nodes and the inner surface of the rib cage). In deer, tuberculous lesions have been described as liquefied abscess-like or caseous (i.e., cheesy)⁷. Additional best practices for dealing with wild game include using different knives for each step of field dressing, skinning, and processing deer; use warm soapy water and/or a 10 percent bleach solution to wash cloth, knife, and other utensils; wear gloves and thoroughly wash hands after processing deer; cook meat to an internal temperature of 165 degrees Fahrenheit^2,8.

There is no specific bovine tuberculosis, Paratuberculosis or Mycoplasmosis treatment in wild WTD. Therefore, prevention measures, such as routine testing and surveillance of wild deer populations, supplemental feeding bans, and culling infected animals in high-risk areas (deer density reduction), may be necessary to control the spread of diseases.

Surveillance is vital for recognizing new or re-emerging bacterial diseases, which helps to improve management and prevention strategies that can protect wildlife, livestock and human health (Figure 3).

A graphic explaining the importance of knowing what bacteria cause what disease in white-tailed deer. — Figure 3. The value of knowing what bacteria cause what disease in white-tailed deer.

Of the three bacteria, only Mycobacterium bovis and Mycobacterium avium (subsp paratuberculosis) can affect both animals and humans. Mycoplasma is a disease of ruminants that may affect other animals but not humans. Due to similarities in names, disease presentation in animals, and transmission pathways, it is best to get a diagnosis and avoid eating meat from an animal that looks sick.

Dr. Nelda Rivera‘s research focuses on the ecology and evolution of new and re-emerging infectious diseases and the epidemiology of infectious diseases, disease surveillance, and reservoir hosts’ determination. She is a member of the Wildlife Veterinary Epidemiology Laboratory and the Novakofski & Mateus Chronic Wasting Disease Collaborative Labs. She earned her M.S. at the University of Illinois at Urbana-Champaign and D.V.M at the University of Panamá, Republic of Panamá.

Dr. Nohra Mateus-Pinilla is a veterinary Epidemiologist working in wildlife diseases, conservation, and zoonoses. She studies Chronic Wasting Disease (CWD) transmission and control strategies to protect the free-ranging deer herd’s health. Dr. Mateus works at the Illinois Natural History Survey- University of Illinois. She earned her M.S. and Ph.D. from the University of Illinois Urbana-Champaign.

References

Bovine Tuberculosis in wild white-tailed deer.
Bovine Tuberculosis in Wild White-tailed Deer: Background and Frequently Asked Questions. Purdue University, Extension – Forestry and Natural Resources.
Garvey M. Mycobacterium avium subspecies paratuberculosis: A possible causative agent in human morbidity and risk to public health safety. Open Vet J. 2018;8(2):172-181. doi: 10.4314/ovj.v8i2.10. Epub 2018 May 19.
Dhama, K., Mahendran, M., Tiwari, R., Dayal Singh, S., Kumar, D., Singh, S. and Sawant, P.M., 2011. Tuberculosis in birds: insights into the Mycobacterium avium infections. Veterinary Medicine International, 2011.
Palmer MV, Kanipe C, Lombard JE, Boggiatto PM. Bovine Tuberculosis at the Interface of Cattle, Wildlife, and Humans. In Tuberculosis: Integrated Studies for a Complex Disease 2023 Apr 1 (pp. 829-846). Cham: Springer International Publishing.
Bernat Pérez de Val and Ana Balseiro. Pequeños rumiantes y tuberculosis en España. Albéitar, núm. 228, septiembre 2019, p. 26-29.
Waters, W.R. and Palmer, M.V., 2015. Mycobacterium bovis infection of cattle and white-tailed deer: translational research of relevance to human tuberculosis. ILAR journal, 56(1), pp.26-43.
Hedman, H.D., Varga, C., Duquette, J., Novakofski, J. and Mateus-Pinilla, N.E., 2020. Food Safety Considerations Related to the Consumption and Handling of Game Meat in North America. Veterinary Sciences, 7(4), p.188.