EQUINE VETERINARY EDUCATION / AE / march 2009 151

Clinical Commentary Glanders and farcy: A re-emerging disease M. Paar Clinic for Horses, Alte Dorfstr. 43-45, 27367 Sottrum, Germany.

The Case Report by Elschner et al. (2009) of a Burkholderia known as farcy). Clinical cases are usually a combination mallei infection in a horse imported from Brazil to Germany of these forms, as in the reported case by Elschner et al. shows the potential risk of an importation of glanders in (2009). They can occur as acute, chronic or subclinical areas free from the disease in spite of all official regulations (latent) disease. Donkeys and mules are believed to for import. The International Animal Health Certificate of develop the more acute form of the disease whereas in the infected animal confirmed that the prescribed horses the chronic or latent form is more common. The complement fixation test (CFT) was negative and during incubation period varies from a few days to many months; veterinary inspection at Frankfurt airport no clinical signs of 2–6 weeks is typical (Anon 2007a). In the case reported by illness were registered. Clinical signs of illness were not Elschner et al. (2009) clinical signs arose 2 weeks after registered until 2 weeks after arrival of the horse in its arrival of the horse at its destination. destination stable. In the cutaneous form, subcutaneous tissues and Knowledge of the disease is the best guarantee for lymph nodes are affected. Cutaneous changes are more early recognition of this zoonosis and for epidemic control. common following bacteraemia than after local Glanders and farcy (the cutaneous form) are caused by contamination of a skin wound. Lymphatic vessels Burkholderia mallei (formerly Pseudomonas mallei), a short, become swollen and corded with development of farcy rod-shaped, Gram-negative, aerobic, facultative buds, swellings that enlarge, ulcerate and drain an oily, intracellular, nonmotile and nonspore-forming bacterium purulent yellow exudate. In addition there may be swelling (Nicoletti 2007). The ability of the bacterium to survive of the joints and painful oedema of the legs. Glanderous outside the host is relatively low. The infectious agent is orchitis is a common symptom in males. normally inactivated by sunlight, warm temperatures and In the nasal form, small nodules inside the nasal drying up in a few days. In dark and humid conditions the passages develop into ulcers, resulting in a thick, purulent bacterium may survive for months (Wittig et al. 2007). yellowish to bloody unilateral or bilateral discharge. Disease caused by B. mallei must be reported to the World Healed ulcers become stellate (starlike) scars. Submaxillary Organization for Animal Health (OIE, Office International lymph nodes become enlarged and indurated, and may des Epizooties, Paris, France). suppurate or drain. There may be severe congestion of the The principal hosts are horses, donkeys and mules. liver and spleen. Orchitis may be present. Chronically infected equids are the natural reservoir. In the pulmonary form, nodules and abscesses Occasional cases of glanders occur in cats, dogs, goats, develop in the lungs. Some infections are inapparent, sheep and camels. Mice and guinea pigs can be others vary from mild dyspnoea to severe respiratory experimentally infected (Nicoletti 2007). Human infections disease with coughing, dyspnoea, high fever (41°C) and arise by contact with secretions or products (meat) of septicaemia. Horses with glanders either die rapidly or live diseased animals. The portals of entry are usually the for several years with chronic abscessation (most often mucous membranes or small lacerations. The disease is regional lymph nodes, lungs, liver, spleen). They may have frequently fatal in man if untreated (Wittig et al. 2007). varying degrees of respiratory difficulty with no fever. Other Glanders is thought to be endemic in parts of the Middle possible clinical signs in affected horses include mild East, Asia, Africa and South America. Between 1998 and depression, decreased food intake and infrequent 2007, cases were reported from Brazil, Turkey, the former defaecation (Anon 2007a; Nicoletti 2007; Wittig et al. USSR, Eritrea, Ethiopia, Iran, Iraq, United Arab Emirates and 2007). Mongolia. The disease may also exist in Pakistan (Anon Differential diagnosis of Burkholderia mallei infection 2007a). The infected horse reported by Elschner et al. includes other bacterial infections, including meliodosis (2009) was imported from Brazil to Germany. (Burkholderia pseudomallei) or diseases caused by In equids, glanders is traditionally categorised into members of the genera Streptococcus, Rhodococcus, nasal form, pulmonary form and cutaneous form (also Pasteurella or Mannheimia (Nicoletti 2007). As shown by 152 EQUINE VETERINARY EDUCATION / AE / march 2009

Elschner et al. (2009) confirmation of the diagnosis requires Animals that test positive for glanders are subjected to one or more test procedures. In the reported case the final euthanasia in nonendemic areas. Treatment even in diagnosis was carried out by means of CFT and skin tests. endemic regions is risky, as infections can spread to man Serodiagnosis is hampered by the considerable number of and other animals and they can become asymptomatic false-positives and -negatives of the internationally carriers (Anon 2007a). prescribed tests (Anon 2007b; Elschner et al. 2009). The In summary, the clinician must be aware that the clinical major problem leading to low sensitivity and specificity of symptoms of glanders are nonspecific, the incubation the CFT and enzyme-linked immunosorbent assay (ELISA) period may be long and the serological tests for importation has been linked to the test antigens currently used, i.e. may give false negative results. The best prevention for crude preparations of whole cells. The development and spread of the disease is keeping it on the list of differential evaluation of serological test kits using well-characterised diagnoses and proceeding with tests in suspicious animals single antigens may overcome this problem (Neubauer imported or reimported from endemic countries. et al. 2005). The Mallein tests (subcutaneous nonocular injection, intrapalpebral injection or administration of References eyedrops of a heat-killed extract of B. mallei) show hypersensitivity reactions in infected equids. Mallein tests Anon (2007a) Glanders, Iowa State University, College of Veterinary can give inconclusive results in acute glanders, or in the Medicine www.cfsph.iastate.edu/Factsheets/pdfs/Glanders.pdf. late stages of chronic disease (Anon 2007a). Culture, Anon (2007b) Manual of Diagnostic Tests and Vaccines for Terrestrial immunohistochemical staining for bacterial antigen and Animals. OIE, World Organisation for Animal Health, Paris. polymerase chain reaction (PCR) assays may be used. If www.oie.int/eng/normes/mmanual/A_00086.htm (16.08.07). necessary, B. mallei isolation can be attempted by Elschner, M.C., Klaus, C.U., Liebler-Tenorio, E., Schmoock, G., Wohlsein, P., Tinschmann, O., Lange, E., Kaden, V., Klopfleisch, R., Melzer, F., inoculation of material into guinea pigs which should be Rassbach, A. and Neubauer, H. (2009) Burkholderia mallei infection highly susceptible (Strauss test). In the reported case the in a horse imported from Brazil. Equine vet. Educ. 21, 147-150. diagnosis was supported by a positive PCR result for lung Neubauer, H., Sprague, L.D., Zacharia, R., Tomaso, H., Al Dahouk, S., tissue of the horse, the positive immunohistological results Wernery, R., Wernery, U. and Scholz, H.C. (2005) Serodiagnosis of for sections of subcutis of 2 guinea pigs and characteristic Burkholderia mallei infections in horses: State-of-the-art and histomorphological findings in sections of liver tissue. perspectives. J. vet. Med. B, 52, 201-205. Re-isolation of the agent failed. As stated by the authors, Nicoletti, P.L. (2007) Glanders, In: Equine Infectious Diseases, Eds: D.C. Sellon and M.T. Long, W.B. Saunders, Philadelphia. pp 345-348. the lack of glanders-positive reaction in the other PCR- tested tissues and the negative immunohistological results Wittig, M.B., Wohlsein, P., Hagen, R.M., Al Dahouk, S., Tomaso, H., Scholz, H.C., Nikolaou, K., Wernery, R., Wernery, U., Kinne, J., Elschner, M. in the tissues of the horse underline the difficulties to and Neubauer, H. (2006) Glanders - a comprehensive review. Deut. diagnose glanders. Tieraerztl. Woch. 113, 321-360.