Infection with Burkholderia mallei (Glanders)

Article 12.10.1.

General provisions

Equids are the major hosts and reservoirs of glanders although scientific data are not available on the occurrence of infection in zebras. Camelids, goats and various carnivores including bears, canids and felids can also be infected but play no significant role in the epidemiology of the disease. Glanders in humans is a rare but potentially fatal disease.

For the purposes of the Terrestrial Code, glanders is defined as an infection of equids with Burkholderia mallei with or without the presence of clinical signs.

The following defines the occurrence of infection with B. mallei:

1. B. mallei has been isolated from a sample from an equid; or

2. antigen or genetic material specific to B. mallei has been identified in a sample from an equid showing clinical or pathological signs consistent with glanders, or epidemiologically linked to a confirmed or suspected case of infection with B. mallei, or giving cause for suspicion of previous contact with B. mallei; or

3. antibodies specific to B. mallei have been identified by a testing regime appropriate to the species in a sample from an equid showing clinical or pathological signs consistent with glanders, or epidemiologically linked to a confirmed or suspected case of infection with B. mallei, or giving cause for suspicion of previous contact with B. mallei.

For the purposes of the Terrestrial Code, the infective period of B. mallei in equids is lifelong and the incubation period shall be six months.

Standards for diagnostic tests are described in the Terrestrial Manual.

Article 12.10.2.

Country or zone free from infection with B. mallei

A country or a zone that does not comply with point 1 a) of Article 1.4.6. may be considered free from infection with B. mallei when:

1. infection with B. mallei has been a notifiable disease in the entire country for at least the past three years;

2. there has been no case of infection with B. mallei during the past three years;

3. a surveillance programme in accordance with Article 12.10.8. has demonstrated no evidence of infection with B. mallei in the past 12 months;

4. imports of equids and their germplasm into the country or zone are carried out in accordance with this chapter.

Article 12.10.3.

Recovery of free status

When a case is detected in a previously free country or zone, freedom from infection with B. mallei can be regained after the following:

1. a standstill of equids and their germplasm from establishments affected or suspected of being affected has been imposed until the destruction of the last case;

2. an epidemiological investigation, including trace-back and trace-forward to determine the likely source of the outbreak, has been carried out;

3. a stamping-out policy, which includes at least the destruction of all infected equids and the disinfection of the affected establishments, has been applied;

4. surveillance in accordance with Article 12.10.8. has been carried out and has demonstrated no evidence of infection in the 12 months after disinfection of the last affected establishment and during that period measures have been in place to control the movement of equids.

When the measures above are not carried out, Article 12.10.2. applies.

Article 12.10.4.

Recommendations for importation of equids from countries or zones free from infection with B. mallei

Veterinary Authorities should require the presentation of an international veterinary certificate attesting that the equid:

1. showed no clinical signs of infection with B. mallei on the day of shipment;

2. either:

   1. was kept for six months prior to shipment, or since birth, in a country or zone or countries or zones free from infection with B. mallei; or

   2. if kept at any time in the past six months in a country or zone not free from infection with B. mallei, was imported in accordance with Article 12.10.5. into a country or zone free from infection with B. mallei.

Article 12.10.5.

Recommendations for importation of equids from countries or zones not free from infection with B. mallei

Veterinary Authorities should require the presentation of an international veterinary certificate attesting that the equid:

1. showed no clinical signs of infection with B. mallei on the day of shipment;

2. was kept for six months prior to shipment, or since birth, in an establishment where no case of infection with B. mallei was reported during the 12 months prior to shipment;

3. was isolated for at least 30 days prior to shipment, and during that time was subjected to a test for infection with B. mallei with negative result carried out on two samples taken 21 to 30 days apart.

Article 12.10.6.

Recommendations for the importation of equine semen

Veterinary Authorities of importing countries should require the presentation of an international veterinary certificate attesting that:

1. on the day of collection, the donor males:

   1. showed no clinical signs of infection with B. mallei;

   2. were examined clinically for signs of orchitis and cutaneous lesions on the penis or other parts of the body, with negative results;

2. the semen was collected, processed and stored in accordance with the relevant recommendations in Chapter 4.5. and in Articles 4.6.5. to 4.6.7.

Article 12.10.7.

Recommendations for the importation of in vivo  derived equine embryos

Veterinary Authorities of importing countries should require the presentation of an international veterinary certificate attesting that:

1. the donor females showed no clinical signs of infection with B. mallei on the day of collection;

2. the embryos were collected, processed and stored in accordance with the relevant recommendations in Chapters 4.7. and 4.9.;

3. the semen used for embryo production complies with Article 12.10.6.

Article 12.10.8.

General principles of surveillance

This article and Article 12.10.9. provide recommendations for surveillance for infection with B. mallei and are complementary to Chapter 1.4. The impact and epidemiology of infection with B. mallei vary in different regions of the world. The surveillance strategies employed should be adapted to the respective epidemiological situation.

Surveillance should address not only the occurrence of clinical signs caused by B. mallei, but also evidence of infection with B. mallei in the absence of clinical signs.

The surveillance systems should be designed:

• to demonstrate that equine populations in a country or zone show no evidence of infection with B. mallei; or

• to detect its introduction into a free population; or

• if B. mallei is known to be present, to allow the estimation of the prevalence and the determination of the distribution of the infection.

The surveillance system in accordance with Chapter 1.4. should be under the responsibility of the Veterinary Authority and should have in place:

1. a system for detecting and investigating outbreaks;

2. a procedure for the collection and transport of samples from suspected cases to a laboratory with appropriate testing capability for diagnosis of infection with B. mallei;

3. a system for recording, managing and analysing diagnostic, epidemiological and surveillance data;

4. a procedure for confirmation of inconclusive test results in an OIE Reference Laboratory.

Diagnosticians and those with regular contact with equids, including private veterinarians, veterinary paraprofessionals and animal handlers should report promptly any suspicion of infection with B. mallei. The reporting system efficacy should be enhanced by awareness programmes and animal identification of equids.

The Veterinary Services should implement, when relevant and taking into account the results of previous surveillance, regular and frequent clinical inspections of equids and targeted serological surveys of high-risk subpopulations or those neighbouring a country or zone infected with B. mallei.

An effective surveillance system is likely to identify suspected cases that require follow-up investigation to confirm or exclude that the cause of the condition is infection with B. mallei. All suspected cases should be investigated as soon as possible and samples should be taken and submitted to a laboratory. This requires that sampling kits and other equipment be available to those responsible for the surveillance. Details of the occurrence of suspected cases and how they were investigated and dealt with should be documented. This should include the results of diagnostic testing and the control measures to which the equids concerned or affected establishments were subjected during the investigation (quarantine, movement control, euthanasia).

Captive wild, feral and wild equine populations should be included in the surveillance.

Article 12.10.9.

Surveillance strategies

The strategy employed should be based on the current knowledge of the epidemiological situation, and the expected results of the surveillance, such as the demonstration of a supposed free status. The populations of equids subject to the surveillance can be covered by passive clinical surveillance, active investigation of suspected cases, or randomised or targeted sampling.

Because infection with B. mallei usually occurs at a very low prevalence, randomised samples should be collected in high numbers. If an increased likelihood of infection in particular geographical locations or subpopulations can be identified, targeted sampling may be more appropriate.

To substantiate freedom from infection in a country or zone, surveillance should be conducted in accordance with the relevant provisions of Article 1.4.6. The relatively high rate of occurrence of false positive reactions to tests for B. mallei should be considered and the rate at which these false positives are likely to occur should be calculated in advance. Every positive result should be investigated to determine whether it is indicative of infection or not. This involves supplementary tests, trace-back and trace-forward, and inspection of individual animals and herds for clinical signs.

Clinical or pathological surveillance and laboratory testing are complementary diagnostic approaches that should always be applied in series to clarify the status of suspected cases. Agent identification should be carried out on any equid serologically positive or showing clinical signs consistent with glanders. Any suspected cases should be considered infected until contrary evidence is produced.

1. Clinical surveillance

   Clinical surveillance aims at detecting clinical signs by close physical examination of equids. However, systematic clinical surveillance is of limited use only, as asymptomatic carrier animals are the main reservoir of the disease.

2. Pathological surveillance

   Systematic pathological surveillance is an effective approach for the detection of infection with B. mallei and should be conducted on dead equids on farms, at slaughterhouses/abattoirs and facilities for the disposal of carcasses of equids. Pathological findings indicating possible infection with B. mallei should be confirmed by agent identification and any isolate should be characterised.

3. Serological surveillance

   Serological surveillance for infection with B. mallei is the preferred strategy. Animal identification and repeated testing of the population are necessary to establish its infection status.

4. Malleinisation

   Frequently used as a surveillance method, malleinisation demonstrates hypersensitivity to antigens of B. mallei. However, this method has shortcomings, such as low sensitivity, interference with other tests and animal welfare concerns.

nb: first adopted in 1968; most recent update adopted in 2018.