Case of much-feared glanders confirmed in German horse

A horse with cutaneous nodules of glanders on the legs.
A horse with cutaneous nodules of glanders on the legs. © University of Zagreb

A horse in Germany has been euthanised after testing positive for the much-feared disease, glanders.

German authorities said it was the first confirmed case of the infection in the country since 1955. The source remains unknown at this stage.

Glanders is a life-threatening, notifiable zoonotic disease which is normally fatal to both animals and humans. It is caused by the bacterium Burkholderia mallei.

Due to its high mortality rate and the small number of organisms needed to establish infection, it is regarded as a potential biological warfare or bioterrorism agent.

Signs of glanders include lung lesions and ulceration of mucous membranes in the respiratory tract. The acute form results in coughing and fever, followed by septicaemia and death within days.

In chronic cases, nodules form on the skin and in the nasal passages, eventually ulcerating. Death can result within months, with those surviving acting as carriers.

Dr Karin Schwabenbauer, chief veterinary officer with Germany’s Directorate of Animal Health, advised the World Organisation for Animal Health (OIE) of the case in a formal notification on January 30.

The case was reported in Bippen, Osnabrück, in Niedersachsen, in a horse who was being readied for export.

Her report said 31 horses were considered susceptible and were being monitored. None has returned a positive test to date.

Schwabenbauer said the affected horse was born in May 2008 and had been kept at the property concerned since November 2014.

On November 26 last year a blood sample was taken in preparation for the horse’s export.

The horse had shown no clinical signs of glanders and had been kept separately from other horses during its pre-export quarantine.

However, it returned a positive test for glanders. A second laboratory confirmed a positive result using a different method. A second blood sample was taken and the results were again positive.

The horse was euthanised on December 13 for diagnostic purposes.

The bacteriological investigations of the animal’s organs showed negative results for Burkholderia mallei, Schwabenbauer reported.

The investigation of skin samples showed what she called doubtful results, but further investigation of scabs of skin samples, which had been fixed in formalin, showed positive results using a different test.

The infection with Burkholderia mallei was confirmed on January 27, she said.

Schwabenbauer said the affected property had been under quarantine since December 1.

All equines housed there have been investigated three times every two weeks, with negative results. The property has been cleaned and disinfected, with the work complated on January 27. The infection has been considered resolved since January 27.

Efforts to trace the source of the infection are being helped by staff at the Friedrich-Loeffler Institute.

“It is known that the affected animal had never been moved outside of Germany,” Schwabenbauer said.

“There might have been indirect contacts to South America. The source of infection is still unknown.”

Last year, researchers sounded a warning over glanders, saying the global horse trade from at-risk regions had the potential to re-establish it in countries that have previously eradicated it.

They suggested that a recent rise in cases of glanders in horses, in combination with worldwide horse trading, might pose a new risk for human infections.

The only known reservoirs of  Burkholderia mallei are single-hooved animals, particularly horses. Chronically infected horses can be asymptomatic but may remain highly infectious.

It is highly infectious and can be transmitted by aerosol, causing invasive fatal disease in combination with resistance to multiple antibiotics.

Although glanders has been eradicated from many Western countries, it recently emerged in Asia, the Middle-East, Africa, and South America.

Due to its rareness, little is known about outbreak dynamics of the disease.

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