WHAT IS GLANDERS? CAUSES, SYMPTOMS, DIAGNOSIS, AND PREVENTION (Part II)

After learning about the causes, routes of transmission, clinical signs, and lesions of glanders in Part 1, livestock farmers should also gain a clear understanding of the diagnostic methods, preventive measures, and appropriate actions to take when animals are suspected of being infected with the disease.
Glanders is a serious infectious disease with zoonotic potential, meaning it can be transmitted to humans. Therefore, early detection, timely isolation, and proper handling in accordance with veterinary regulations play a crucial role in controlling the source of infection. In Part 2, Fivevet will guide you through the diagnostic methods for glanders, disease prevention measures, and important considerations when a suspected case is detected. 1. Diagnosis of Glanders
The diagnosis of glanders requires a combination of different diagnostic methods. It should not be based solely on clinical signs, especially during the early stages of the disease or in chronic cases where clinical manifestations may be mild or non-specific.
a. Clinical Diagnosis
Clinical diagnosis is primarily based on characteristic signs such as inflammation of the nasal mucosa and the formation and development of nodules, tumors, and ulcerative lesions on the affected animal's body.
However, clinical diagnosis alone is not sufficient to confirm glanders, particularly in the early stages of the disease. Therefore, additional laboratory tests should be performed to obtain a more accurate diagnosis.
b. Bacteriological Diagnosis
Samples may be collected from the animal’s secretions or internal organs for bacterial isolation. In bacteriological diagnosis, a suspension prepared from the collected samples can be injected into the peritoneal cavity of guinea pigs to observe the development of suppurative inflammation of the testes and the tunica vaginalis, which may aid in the identification of the causative bacterium. c. Diagnosis by the Mallein Allergy Test
The Mallein test is a diagnostic method used for the detection of glanders. Several types of Mallein tests are available, among which the ophthalmic (eye) allergy test is the most commonly used.
Procedure: Instill 0.2 mL of concentrated Mallein into the conjunctival sac of the animal. The results are then evaluated twice:
- First evaluation: 8–12 hours after administration.
- Second evaluation: 16–24 hours after administration.
Interpretation of results:
- Positive reaction: The conjunctiva becomes inflamed and swollen, accompanied by ocular discharge.
- Suspect reaction: The conjunctiva is inflamed and swollen but without ocular discharge; only lacrimation and a clear inflammatory exudate are observed within 24 hours, after which the condition resolves.
In cases of a suspect reaction, the test should be repeated after 3 weeks. To improve diagnostic accuracy, it is recommended that the Mallein test be performed in conjunction with serological testing. In some countries, intradermal allergic testing with Mallein is also used.
d. Serological Diagnosis
Serological diagnosis is often used when allergic reactions yield inconclusive results. Two commonly used serological tests include:
- Agglutination test:
An agglutination test is considered positive only when the agglutination titer is 1/800 or higher.
- Complement fixation test:
This test provides accurate results; however, blood samples must be taken at the correct time. For ocular allergy testing, blood samples should be taken 3 weeks after the second evaluation. For cutaneous allergy testing, blood samples should be taken 3 months before the test is performed.
2. Can Glanders Be Transmitted to Humans?
Yes. Glanders is a zoonotic disease, meaning it can be transmitted from animals to humans. People may become infected through direct contact with nasal secretions, pus, ulcerative lesions, excreta, or contaminated equipment from infected animals.
Therefore, when an animal is suspected of having glanders, it should be isolated immediately. Direct contact should be minimized, appropriate personal protective equipment (PPE) should be used when handling or caring for the animal, and the veterinary authorities should be notified for inspection and guidance on proper disease control measures in accordance with regulations.
3. Prevention of Glanders
Prevention is the most important measure in controlling glanders, as the disease can spread within animal populations and poses a risk of transmission to humans.
- In areas where glanders is endemic, susceptible animals should be tested using the Mallein test twice a year. Animals identified as carriers, subclinically infected, or clinically affected should be handled in accordance with veterinary regulations.
- During the import, export, or introduction of new equids, strict screening using the Mallein test should be carried out to detect and eliminate infected animals and carriers, thereby preventing the introduction of the pathogen into the herd.
- In addition, good veterinary hygiene measures must be implemented in livestock facilities. Farmers need to maintain hygiene in barns, holding areas, grazing areas, feed troughs, water troughs, and care equipment. Regular disinfection should be carried out using appropriate products, at the correct concentration and according to the instructions for use. Specialized disinfectants for livestock farming such as Five-BGF, Five-B.K.G, Five-Perkon 3S, or Five-Iodine can be chosen depending on the farm's specific conditions.
- Combine this with the use of products that support the control of external parasites such as Five-Tox 250, Five-Permethrin, and Five-Cymethrin.
- Do not share feeding or watering equipment between herds that have not been confirmed free of disease.
- Ensure proper control of feed and water sources to minimize the risk of pathogen contamination.
- Regularly monitor the health status of the herd.
- Provide appropriate nutrition and management to enhance the animals' immune resistance.
- Administer routine vaccinations against equine diseases, such as tetanus, equine influenza, West Nile virus, Eastern and Western equine encephalitis, and rabies, to reduce the risk of other infectious diseases. However, vaccination should not currently be considered a specific preventive measure against glanders. Prevention and control of glanders should focus on quarantine measures, early detection, isolation of infected animals, proper cleaning and disinfection of facilities, and management of cases in accordance with veterinary regulations. 4. Can Glanders Be Treated?
At present, treatment of animals infected with glanders is generally not recommended. Infected animals should be handled in accordance with veterinary regulations, which typically require euthanasia and deep burial with appropriate disinfectants.
Treatment poses a significant risk because the causative agent may continue to spread to healthy animals and can also be transmitted to humans. Therefore, when an animal is suspected of having glanders, it should be isolated immediately, direct contact should be minimized, and the veterinary authorities should be notified promptly for guidance on proper disease control measures in accordance with applicable regulations.
5. Important Considerations When an Animal Is Suspected of Having Glanders
Because glanders is a zoonotic disease that can be transmitted to humans, livestock owners should not attempt to treat the animal themselves, perform necropsies, or come into direct contact with nasal discharges, pus, or ulcerative lesions from suspected cases.
If an animal exhibits signs such as chronic rhinitis, greenish-yellow or blood-tinged nasal discharge, skin nodules or ulcers, enlarged lymph nodes, coughing, difficulty breathing, intermittent fever, weight loss, or general weakness, it should be isolated immediately and a veterinarian should be contacted for examination and diagnosis.
To effectively prevent glanders, strict veterinary hygiene measures should be implemented, including regular cleaning and disinfection of animal housing, periodic screening using the Mallein test, careful control of newly introduced animals, and prompt management of suspected cases in accordance with veterinary regulations.
This article was prepared by the Field Technical Department, Central Veterinary Medicine Joint Stock Company No. 5 (Fivevet).
https://khoathuy.vnua.edu.vn/phong-ngua-benh-ty-thu-o-ngua.html
Nguyen Ba Hien et al. Veterinary Infectious Diseases Textbook. Agricultural Academy Publishing House.
Frequently Asked Questions (FAQs)
1. What methods are used to diagnose glanders?
Glanders should be diagnosed using a combination of methods, including clinical examination, bacteriological diagnosis, the Mallein allergy test, and serological testing. Diagnosis should not be based solely on clinical signs or external symptoms.
2. What is the role of the Mallein test in the diagnosis of glanders?
The Mallein test is a commonly used diagnostic tool for glanders. In the ophthalmic Mallein test, Mallein is instilled into the animal’s conjunctival sac, and the eye is subsequently monitored for inflammation, swelling, and ocular discharge at specified intervals.
3. Can glanders be transmitted to humans?
Yes. Glanders is a zoonotic disease that can be transmitted from animals to humans. Infection may occur through direct contact with nasal secretions, pus, ulcerative lesions, excreta, or contaminated equipment from infected animals.
4. Should animals with glanders be treated?
No. Treatment of animals affected by glanders is generally not recommended. Infected animals should be managed in accordance with veterinary regulations to prevent the spread of the pathogen to healthy animals and humans.
5. What should be done when an animal is suspected of having glanders?
If an animal shows signs suggestive of glanders, it should be isolated immediately, and direct contact should be minimized. Livestock owners should not attempt to treat the animal or perform a necropsy. Appropriate personal protective equipment (PPE) should be used when handling the animal, and the veterinary authorities should be contacted for inspection and guidance on proper disease management in accordance with regulations.