Glanders

Glanders is a contagious, zoonotic infectious disease. A zoonotic disease is one that spreads from animals to humans. This sickness is caused by a specific bacterium named Burkholderia mallei. It primarily affects equines, such as horses, mules, and donkeys. However, other animals like dogs, cats, pigs, and goats can also contract it. Because it can jump to people, it is a major concern for public health.

The transmission of glanders happens through several specific pathways. Animals often become infected by ingesting contaminated drinking water or animal feed. Once the bacterium is in a host, it can spread through direct contact. This contact involves touching the infected animal's tissues or body fluids. In humans, the B. mallei pathogen enters the body in three main ways. It can enter through the inhalation of germs, through the oral or nasal mucosal surfaces, or through abrasions in the skin.

When the disease takes hold, it presents in two distinct clinical forms. The acute form is characterized by a rapid and severe progression. Patients or animals experience fever, coughing, and an infectious nasal discharge. This version can lead to septicaemia, which is a serious blood infection, and death within just a few days. The chronic form develops much more slowly over a longer period. In this version, subcutaneous nodules and nasal nodules form. These nodules eventually undergo ulceration, which means they turn into open sores. While death may take months, survivors often act as carriers of the bacteria.

To identify the presence of the disease, scientists use the mallein test. This is a sensitive and specific clinical diagnostic tool. The test uses mallein, which is a protein fraction of the B. mallei organism. This protein is administered either as an eye drop or via intradermopalpebral injection. If the subject is infected, the eyelid will show marked swelling within one to two days. This method allows veterinarians to detect the infection even when symptoms are not obvious.

History shows that glanders has been a significant threat for centuries. The physician Hippocrates provided a description of the disease around 425 BCE. During the Middle Ages and through the 1900s, it posed a major risk to military forces. In 1704, glanders may have diminished the cavalry horses of Marshal Tallard. This reduction in horse strength helped the Duke of Marlborough win the Battle of Blenheim. In the 18th century, the École Nationale Vétérinaire d'Alfort saw glanders as their most common equine disease. It was also the disease most likely to cause death among their patients.

The dangerous nature of B. mallei has led to its classification as a potential biological warfare agent. This is due to the high mortality rate in humans and the small number of organisms needed for infection. During World War I, it was believed that German agents deliberately spread the disease to Russian horses. In World War II, the Japanese used B. mallei at the Unit 731 Pingfang Institute and Unit 100 facilities. They infected prisoners of war, civilians, and horses. The United States studied the agent, known as agent LA, between 1943 and 1944. Although the U.S. did not weaponize it, the Soviet Union allegedly used weaponized B. mallei during the Soviet-Afghan War between 1982 and 1984.

Today, the global status of glanders varies by region. The disease is currently endemic in Africa, Asia, the Middle East, and Central and South America. However, it has been eradicated in North America, Australia, and most of Europe. This eradication was achieved through zoological observation, quarantine restrictions, and the destruction of infected animals. In the United States, no cases were reported from 1945 until a laboratory researcher was accidentally exposed in 2000. In the United Kingdom, glanders is a notifiable disease, but no cases have been reported since 1928.

Modern science continues to focus on the risks posed by this pathogen. The US NIH and the US CDC have classified B. mallei as a category B priority pathogen. This classification is due to its high infectivity via aerosols and its resistance to many common antibiotics. Currently, there is no licensed vaccine for glanders in the United States. This lack of a vaccine, combined with the difficulty of rapid diagnosis, makes research into new vaccines a high priority. Scientists hope to protect both military personnel and civilians living in endemic areas.