Infection with Taylorella equigenitalis (Contagious equine metritis)

Article 12.2.1.

General provisions

This chapter addresses the occurrence of clinical or asymptomatic infection of a mare caused by Taylorella equigenitalis as well as the presence of T. equigenitalis on the genital mucous membrane surface in the male horse.

For the purposes of the Terrestrial Code, the following defines infection with T. equigenitalis:

1. T. equigenitalis has been isolated and identified as such from a genital swab sample from a horse; or

2. nucleic acid specific to T. equigenitalis has been detected in a sample from a horse; or

3. antigen specific to T. equigenitalis has been detected in a sample from a horse showing clinical or pathological signs consistent with infection with T. equigenitalis, or epidemiologically linked to a confirmed or suspected case of infection with T. equigenitalis.

For the purposes of the Terrestrial Code:

• due to long-term persistence of T. equigenitalis in horses, in the absence of effective treatment, the infective period shall be lifelong;

• the incubation period in mares shall be 14 days.

Standards for diagnostic tests are described in the Terrestrial Manual.

For the purposes of this chapter, a temporary importation refers to the introduction of horses into a country or zone, for a defined period of time, not exceeding 90 days, during which the risk of transmission of the infection is mitigated through specific measures under the supervision of the Veterinary Authority. Temporary imported horses are re-exported at the end of this period. The duration of the temporary importation period and the destination after this period, as well as the conditions required to leave the country or zone, should be defined in advance.

When authorising the importation or transit of the commodities listed in this chapter, with the exception of those listed in Article 12.2.2., Veterinary Authorities should require the conditions prescribed in this chapter relevant to the T. equigenitalis status of the exporting country, zone or herd.

Article 12.2.2.

Safe commodities

When authorising importation or transit of the following commodities, Veterinary Authorities should not require any T. equigenitalis-related conditions, regardless of the animal health status of the exporting country, zone or herd:

1. geldings;

2. milk and milk products;

3. meat and meat products;

4. hides and skins;

5. hooves;

6. gelatine and collagen.

Article 12.2.3.

Herd free from infection with T. equigenitalis

1. Prerequisite

   Infection with T. equigenitalis has been a notifiable disease in the entire country for at least the past two years.

2. Qualification

   To qualify as free from infection with T. equigenitalis, a herd should satisfy the following conditions:

   1. it is under the control of the Veterinary Authority;

   2. no case has occurred for at least two years;

   3. all horses from the herd have been subjected to T. equigenitalis tests, with negative results, on samples collected on three occasions within a 12-day period, with an interval of no less than three days between sample collections. Horses must have not been treated with antibiotics for at least 7 days prior to the first sampling, nor subjected to antiseptic washing of genital mucous membrane for at least 21 days prior to the first sampling;

   4. any stored semen was subjected to a test for detection of nucleic acid of T. equigenitalis with negative results, carried out on an aliquot of the stored semen.

3. Maintenance of freedom

   1. the requirements in points 1, 2 a) and 2 b) of Article 12.2.3. are met;

   2. appropriate surveillance capable of detecting infection with T. equigenitalis even in the absence of clinical signs is in place; this may be achieved through a surveillance programme in accordance with Chapter 1.4. and this chapter;

   3. the introduction of horses and their germinal products into the herd is carried out in accordance with the importation conditions for these commodities listed in this chapter.

4. Recovery of freedom

   When a case is detected in a previously free herd the free status should be suspended until the following conditions are met:

   1. the disinfection of the establishment has been applied;

   2. not before 21 days after the last removal or the last treatment of an infected horse, all horses have been subjected to a test for the detection of the agent, with negative results, on samples collected on three occasions, within a 12-day period with an interval of no less than three days between sample collections;

   3. any fresh semen from all infected horses in the herd has been destroyed; aliquots of each collection of stored semen from all infected horses in the herd were subjected to a test for detection of nucleic acid of T. equigenitalis with negative results; and all positive stored semen has been destroyed;

   4. the introduction of horses and their germinal products into the herd is carried out in accordance with the importation conditions for these commodities listed in this chapter.

Article 12.2.4.

Recommendations for importation of stallions or mares

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

1. mares showed no clinical sign of infection with T. equigenitalis on the day of shipment;

AND

2. horses have been:

   1. kept since birth or for at least two years prior to shipment in a herd that has been free from infection with T. equigenitalis;

   OR

2. 1. kept for at least the last 60 days in a herd in which no case has been reported during that period;

      AND

   2. subjected to tests for the detection of the agent, with negative results, carried out on samples collected on three occasions within a 12-day period, with an interval of no less than three days between sample collections, the last one being carried out within 30 days prior to shipment. Horses have not been treated with antibiotics for at least 7 days nor subjected to antiseptic washing of genital mucous membranes for at least 21 days prior to the first sample collection, and have not been mated or inseminated after the first sampling.

Article 12.2.5.

Recommendations for temporary importation of stallions and mares

When importing on a temporary basis stallions or mares that do not comply with recommendations in Article 12.2.4. for purposes other than breeding and rearing, Veterinary Authorities should:

1. require:

   1. the horses be accompanied by a passport in accordance with the model contained in Chapter 5.12. or be individually identified as belonging to a high health status subpopulation as defined in Chapter 4.17.;

   2. the presentation of an international veterinary certificate attesting that the mares showed no clinical sign of infection with T. equigenitalis on the day of shipment;

   3. the duration of the temporary importation period, the destination after this period, and the conditions required to leave the country or zone be defined;

2. ensure that during their stay in the country or zone, the horses:

   1. are not used for breeding (including artificial insemination, semen collection, use as teasers) and do not have any sexual contact with other horses;

   2. are not subjected to any practice that may represent a risk of transmission of infection with T. equigenitalis;

   3. are kept and transported individually in stalls and vehicles/vessels which are subsequently cleaned and disinfected before re-use.

Article 12.2.6.

Recommendations for importation of semen from stallions

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

1. semen was collected in an approved centre and collection, processing and storing were done in accordance with Chapter 4.6.; and

EITHER

2. the donor stallion was kept in a herd free from infection with T. equigenitalis;

OR

3. 4. the donor stallion was kept for at least 60 days prior to semen collection in a herd in which no case has been reported during that period; and

   5. the donor stallion was subjected to tests for the detection of the agent, with negative results, carried out on samples collected on three occasions, within a 12-day period with an interval of no less than three days between sample collections, the last one being carried out within 30 days prior to shipment. Horses have not been treated with antibiotics for at least 7 days nor subjected to antiseptic washing of genital mucous membranes for at least 21 days prior to the first sample collection, and have not been mated or inseminated after the first sampling;

OR

4. aliquots of fresh semen were subjected to culture and a test for detection of nucleic acid of T. equigenitalis with negative results, carried out immediately prior to processing and on an aliquot of semen collected within 15-30 days after the first collection of the semen to be exported;

OR

5. aliquots of stored semen corresponding to the oldest and the most recent collection were subjected to culture and a test for detection of nucleic acid for T. equigenitalis with negative results.

Article 12.2.7.

Recommendations for importation of oocytes or embryos of horses

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

1. the oocytes and embryos were collected, processed and stored in approved centres following the general provisions in accordance with Chapters 4.8., 4.9. and 4.10.;

2. the donor mare showed no clinical signs of infection with T. equigenitalis on the day of collection;

AND

for the importation of embryos:

3. the semen used for embryo production complied with Article 12.2.6. and Chapters 4.6. and 4.7.

Article 12.2.8.

Surveillance

1. General principles of surveillance

   Surveillance for infection with T. equigenitalis is relevant for establishments seeking to achieve and demonstrate freedom from infection, as well as being part of an official control programme in countries where the disease is endemic.

   The surveillance strategy chosen should be adequate to detect infection with T. equigenitalis even in the absence of clinical signs.

   The Veterinary Services should implement programmes to raise awareness among owners, breeders and workers who have day-to-day contact with horses, as well as veterinarians, veterinary paraprofessionals and diagnosticians, who should report promptly to them any suspicion of infection with T. equigenitalis.

   Under the responsibility of the Veterinary Authority, Member Countries should have in place an early warning system in accordance with Article 1.4.5. and a system for recording, managing and analysing diagnostic and surveillance data.

2. Clinical surveillance

   Clinical surveillance aims at detecting clinical signs by close physical examination of horses and based on reproductive performance. However, clinical surveillance should be complemented by culture for T. equigenitalis and molecular testing, as asymptomatic carriers play an important role in the maintenance and transmission of the infection.

3. Agent surveillance

   An active programme of surveillance of horses to detect cases should be implemented to establish the status of a country, zone or herd. Culture for T. equigenitalis and molecular testing are the most effective methods of detection of a case.

   Stored semen should be included in surveillance programmes. It represents a valuable source of material and may be very helpful in contributing to retrospective studies, including providing support for claims of freedom from infection and may allow certain studies to be conducted more quickly and at lower cost than other approaches. Samples can be gathered through representative sampling or following a risk-based approach.

4. Serological surveillance

   Serological surveillance is not the preferred strategy for detecting T. equigenitalis. If used, serology should be done in conjunction with agent identification in assessing the status of a mare that may have been infected with T. equigenitalis. The usefulness of serological tests is further described in the Terrestrial Manual.

nb: first adopted in 1982; most recent update adopted in 2024.