Terrestrial Animal Health Code
Terrestrial Animal Health Code |
Infection with Theileriaequi and Babesiacaballi (Equine piroplasmosis)
General provisions
The infection with Theileria equi (T. equi) or Babesia caballi (B. caballi) established after transmission of these pathogenic agents through competent ticks or iatrogenic practices may be asymptomatic or may cause a clinical disease known as equine piroplasmosis. Vertical transmission from mares to foals has also been reported. This chapter deals not only with clinical disease, but also with asymptomatic infections.
Animals susceptible to infection with T. equi or B. caballi are primarily domestic and wild equids. Although old-world camelids are susceptible to infection and are potential reservoirs, they are not found to play a significant role in the epidemiology of the disease.
Equids infected with T. equi or B. caballi may remain carriers of these blood parasites for long periods, sometimes lifelong and act as sources of infection for competent tick vectors, including species of the genera Dermacentor, Rhipicephalus, Hyalomma and Amblyomma.
For the purposes of the Terrestrial Code, the following defines infection with T. equi or B. caballi:
T. equi or B. caballi has been observed and identified as such in a sample from an equid; or
nucleic acid specific to T. equi or B. caballi has been detected in a sample from an equid showing clinical or pathological signs consistent with infection with T. equi or B. caballi, or epidemiologically linked to a confirmed or suspected case of infection with T. equi or B. caballi; or
antibodies specific to T. equi or B. caballi have been detected in a sample from an equid showing clinical or pathological signs consistent with infection with T. equi or B. caballi, or epidemiologically linked to a confirmed or suspected case of infection with T. equi or B. caballi.
For the purposes of the Terrestrial Code, the incubation period of infection with T. equi or B. caballi in equids shall be 30 days and the infective period shall be lifelong.
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. Temporarily 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 12.7.2., Veterinary Authorities should require the conditions prescribed in this chapter relevant to the status of infection with T. equi and B. caballi of the exporting country or zone.
Standards for diagnostic tests are described in the Terrestrial Manual.
Safe commodities
When authorising importation or transit of the following commodities, Veterinary Authorities should not require any conditions related to infection with T. equi or B. caballi, regardless of the animal health status of the exporting country or zone:
milk and milk products;
meat and meat products;
hides and skins;
hooves;
gelatine and collagen;
semen collected in accordance with the relevant chapters of the Terrestrial Code;
sterile filtered horse serum;
embryos collected, processed and stored in accordance with Chapters 4.8., 4.9. and 4.10.
Country or zone free from infection with T. equi and B. caballi
Historical freedom as described in Chapter 1.4. does not apply to infection with T. equi and B. caballi.
A country or a zone may be considered free from infection with T. equi and B. caballi when:
infection with T. equi and infection with B. caballi have been notifiable diseases in the entire country for at least the past 10 years and, in the country or zone:
there has been no case of infection with T. equi and no case of infection with B. caballi during the past six years; and
a surveillance programme performed in accordance with Article 12.7.8. has demonstrated no evidence of infection with T. equi and no evidence of infection with B. caballi for the past six years and has considered the presence or absence of competent vectors in the epidemiological situation;
importation of equids into the country or zone is carried out in accordance with this chapter. A country or zone free from infection with T. equi and B. caballi in which seropositive or infective horses were imported temporarily in accordance with Article 12.7.6. will not lose its free status provided an epidemiological investigation demonstrates that there has been no transmission of infection;
a country or zone free from infection with T. equi and B. caballi adjacent to an infected country or zone should include a high-risk area in which surveillance is conducted in accordance with Article 12.7.8.
Recovery of a free status
When infection with T. equi or B. caballi is detected in a previously free country or zone, Article 12.7.3. applies.
Recommendations for the importation of equids
Veterinary Authorities should require the presentation of an international veterinary certificate attesting that:
the animals showed no clinical signs of infection with T. equi or B. caballi on the day of shipment, and
EITHER:
the animals were kept in a country or zone free from infection with T. equi and B. caballi since birth;
OR
were subjected to serological and agent identification tests with molecular techniques for the detection of T. equi and B. caballi with negative results carried out on a blood sample taken within the 14 days prior to shipment; and
were maintained free from competent ticks in accordance with Article 12.7.7. and not subjected to any practice that may present a risk of iatrogenic transmission of infection with T. equi or B. caballi during the 30 days prior to sampling and after sampling until shipment; and
have not been treated with antiparasitic drugs capable of masking an infection with T. equi and B. caballi, for at least six months prior to sampling.
Recommendations for the temporary importation of horses
If the importation of horses on a temporary basis does not comply with the recommendations in Article 12.7.5., Veterinary Authorities of importing countries should:
require:
that 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.;
the presentation of an international veterinary certificate attesting that the horses:
that 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, be defined;
ensure that during their stay in the country or zone:
the horses are protected from ticks in accordance with Article 12.7.7.;
horses are examined daily for the presence of ticks with particular attention to the ears, false nostrils, inter-mandibular space, mane, lower body areas, including the axillae, and inguinal region, and the perineum and tail, with negative results;
the horses are not subjected to any practice that may represent a risk of iatrogenic transmission of infection with T. equi or B. caballi.
Protecting equids from ticks
Under the direct supervision of the Veterinary Authority:
equids are kept in tick-protected facilities and transported in protected vehicles/vessels according to point 3;
equids have received preventive treatment in accordance with the manufacturer's recommendations with an acaricide effective against the competent ticks.
The establishment or facility should be approved by the Veterinary Authority and the means of protection should at least comprise the following:
measures to limit or eliminate habitats for competent tick vectors should be implemented for an appropriate time and over an appropriate distance in the vicinity of the area where equids are kept;
the facility and immediate surroundings of the stables and exercise or competition areas should be treated with an effective acaricide before the arrival of equids.
When transporting equids through infected countries or zones:
the vehicle/vessel should be treated with an effective acaricide before transporting the animals;
preventive treatment of the equids with an acaricide with an extended residual effect that lasts at least for the duration of any stopover during the trip should be conducted.
Surveillance strategies
General principles of surveillance
A Member Country should justify the surveillance strategy chosen as being adequate to detect the presence of infection with T. equi and the presence of infection with B. caballi, given the prevailing epidemiological situation in accordance with Chapter 1.4. and Chapter 1.5. and under the responsibility of the Veterinary Authority.
An active programme of surveillance of equids to detect evidence of infection with T. equi and evidence of infection with B. caballi by serological or agent identification molecular testing is required to establish the status of a country or zone, considering that asymptomatic carriers play an important role in the maintenance and transmission of the infection.
The Veterinary Services should implement programmes to raise awareness among veterinarians, horse breeders, owners, keepers, and riders who have day-to-day contact with equids, as well as veterinary paraprofessionals and diagnosticians, who should report promptly to them any suspicion of infection with T. equi and any suspicion of infection with B. caballi.
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.
Clinical surveillance
Clinical surveillance aims at detecting clinical signs by close physical examination of equids.
Serological and agent surveillance
An active programme of surveillance of equids to detect evidence of infection with T. equi and evidence of infection with B. caballi by serological or agent identification testing with molecular techniques is required to establish the status of a country or zone considering that asymptomatic carriers play an important role in the maintenance and transmission of the infection.
The study population used for a serological survey should be representative of the population at risk in the country or zone.
Surveillance in high-risk areas
Disease-specific enhanced surveillance in a free country or zone should be carried out over an appropriate distance from the border with an infected country or zone, based upon geography, climate, history of infection and other relevant factors. The surveillance should be carried out particularly over the border with that country or zone unless there are relevant ecological or geographical features likely to limit the spatial distribution and thereby prevent the infestation of equids from competent ticks and interrupt the transmission of infection with T. equi or B. caballi.
Vector surveillance
Infection with T. equi or B. caballi is transmitted between equine hosts by species of competent ticks including species of the genera Dermacentor, Rhipicephalus, Hyalomma, and Amblyomma.
Vectorsurveillance is aimed at demonstrating the absence of tick vectors or defining high, medium and low-risk areas and local details of seasonality by determining the various species present in an area, their respective seasonal occurrence, and abundance. Vectorsurveillance has particular relevance to potential areas of spread. Long term surveillance can also be used to assess vector abatement measures or to confirm the continued absence of vectors.
Vectorsurveillance sampling should be scientifically based. The choice of collection methods to be used in vectorsurveillance and the frequency of their use should consider the size and ecological characteristics of the area to be surveyed as well as the biology and behavioural characteristics of the local vector species of competent ticks.
The use of a vectorsurveillance system to detect the presence of circulating T. equi or B. caballi is not recommended as a routine procedure. Rather, animal-based surveillance strategies are preferred to detect T. equi or B. caballi transmission.
nb: first adopted in 1982; most recent update adopted in 2024.
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