Infection with Rift Valley fever virus

Article 8.16.1.

General provisions

1. The aim of this chapter is to mitigate the animal and public health risks posed by Rift Valley fever (RVF) and to prevent its international spread.

2. For the purposes of this chapter:

   1. 'epidemic area' means a part of a country or zone in which an epidemic of RVF is occurring, and which does not correspond to the definition of zone;

   2. 'epidemic of RVF' means a sudden and unexpected change in the distribution or increase in incidence of, or morbidity or mortality of RVF;

   3. 'inter-epidemic period' means a period between two epidemics;

   4. 'susceptible animals' means ruminants and dromedary camels.

3. Humans and many animal species can be affected by RVF.  For the purposes of the Terrestrial Code, RVF is defined as an infection of susceptible animals with Rift Valley fever virus (RVFV).

4. The following defines the occurrence of infection with RVFV:

   1. RVFV, excluding vaccine strains, has been isolated and identified as such from a sample from a susceptible animal; or

   2. antigen or nucleic acid specific to RVFV, excluding vaccine strains, has been detected in a sample from a susceptible animal showing clinical signs or pathological lesions consistent with RVF, or with epidemiological links either to a confirmed or suspected case of RVF or to a human infected with RVFV, or giving cause for suspicion of association or contact with RVFV; or

   3. antibodies specific to RVFV that are not the consequence of vaccination, have been detected in a sample from a susceptible animal showing clinical signs or pathological lesions consistent with RVF, or with epidemiological links either to a confirmed or suspected case of RVF or to a human infected with RVFV, or giving cause for suspicion of association or contact with RVFV.

5. For the purposes of the Terrestrial Code, the infective period for RVF shall be 14 days and the incubation period shall be seven days.

6. In areas where RVFV is present, epidemics of RVF may occur following favourable climatic and other environmental conditions and availability of susceptible animal and competent vector populations. Epidemics are separated by inter-epidemic periods. The transition from an inter-epidemic period to an epidemic complies with point 1 e) of Article 1.1.3. in terms of notification.

7. When authorising importation or transit of the commodities covered in the chapter, with the exception of those listed in Article 8.16.2., Veterinary Authorities should require the conditions prescribed in this chapter relevant to the RVF status of the susceptible animal population of the exporting country.

8. Standards for diagnostic tests and vaccines are described in the Terrestrial Manual.

Article 8.16.2.

Safe commodities

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

1. hides and skins;

2. wool and fibre;

3. extruded dry pet food;

4. heat-treated meat products in a hermetically sealed container with an F0 value of 3 or above.

Article 8.16.3.

Country or zone free from RVF

A country or a zone may be considered free from RVF when infection with RVFV is notifiable in the entire country and either:

1. it meets the requirements for historical freedom in Article 1.4.6.; or

2. it meets the following conditions:

   1. an on-going specific surveillance programme in accordance with Chapter 1.4. has demonstrated no evidence of infection with RVFV in susceptible animals in the country or zone for a minimum of ten years; and

   2. during that period no indigenous infections in humans have been reported by the public health authorities in the country or zone.

A country or zone free from RVF will not lose its free status through the importation of susceptible animals that are seropositive, so long as they are either permanently identified as such or destined for immediate slaughter.

Article 8.16.4.

Country or zone infected with RVFV

A country or zone infected with RVFV is one that does not meet the requirements of Article 8.16.3.

Article 8.16.5.

Strategies to protect from vector attacks during transport

Strategies to protect susceptible animals from vector attacks during transport should take into account the local ecology and potential insecticide resistance of the vectors. Protection measures include:

1. treating animals and vehicles/vessels with insect repellents and insecticides prior to and during transportation;

2. loading, transporting and unloading animals at times of low vector activity;

3. ensuring vehicles/vessels do not stop en route unless the animals are protected from vector attacks;

4. using historical and current information to identify lower risk ports and transport routes.

Article 8.16.6.

Recommendations for importation of susceptible animals from countries or zones free from RVF

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

1. were kept in a country or zone free from RVF since birth or for at least 14 days prior to shipment;

AND

2. either:

   1. were vaccinated at least 14 days prior to leaving the free country or zone; or

   2. did not transit through an epidemic area.

Article 8.16.7.

Recommendations for importation of susceptible animals from countries or zones infected with RVFV

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

1. showed no clinical signs of RVF on the day of shipment;

2. met one of the following conditions:

   1. were vaccinated against RVF at least 14 days prior to shipment; or

   2. were held for at least 14 days prior to shipment in a vector-protected quarantine station, which is located in an area of demonstrated low vector activity. During this period the animals showed no clinical sign of RVF;

AND

3. did not originate in or transit through an epidemic area.

Article 8.16.8.

Recommendations for importation of semen and in vivo derived embryos of susceptible animals from countries or zones infected with RVFV

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

1. showed no clinical signs of RVF within the period from 14 days prior to and 14 days following collection of the semen or embryos;

AND

2. either:

   1. were vaccinated against RVF at least 14 days prior to collection; or

   2. were subjected to a serological test on the day of collection, with positive result; or

   3. were subjected to a serological test on two occasions with negative results on the day of collection and at least 14 days after collection; or

   4. were subjected to a test for the detection of the agent with negative result on the day of collection.

Article 8.16.9.

Recommendations for importation of fresh meat and meat products from susceptible animals from countries or zones infected with RVFV

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

1. the entire consignment of meat or meat products comes from:

   1. susceptible animals that showed no clinical signs of RVF within 24 hours before slaughter;

   2. susceptible animals that were slaughtered in an approved slaughterhouse/abattoir and were subjected to ante- and post-mortem inspections in accordance with Chapter 6.3. with favourable results;

   3. carcasses that were submitted to maturation at a temperature above 2°C for a minimum period of 24 hours following slaughter;

2. the necessary precautions were taken to avoid contact of the meat or meat products with any potential source of RVFV.

Article 8.16.10.

Recommendations for importation of milk and milk products from susceptible animals from countries or zones infected with RVFV

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

1. was subjected to pasteurisation; or

2. was subjected to a combination of treatments with equivalent performance as described in the Codex Alimentarius Code of Hygienic Practice for Milk and Milk Products.

Article 8.16.11.

Surveillance

Surveillance for RVF should be carried out in accordance with Chapter 1.4.

Surveillance for arthropod vectors should be carried out in accordance with Chapter 1.5., especially to determine areas of low vector activity.

Detection of RVFV in vectors has low sensitivity and therefore is not a recommended surveillance method.

An epidemic should be suspected in countries or zones infected with RVFV, or countries or zones adjacent to a country or zone in which epidemics have been notified, when ecological conditions favour the breeding of large numbers of mosquitoes and other vectors with concurrent or consequent occurrence of an increased number of abortions, and mortality particularly in new-born susceptible animals showing clinical signs or pathological lesions consistent with RVF, or reports of indigenous infection in humans.

Ecological conditions can be assessed through the sharing and analysis of meteorological data, and data on precipitation and water levels, as well as the monitoring of vector activity. Clinical surveillance targeted at abortions and the use of sentinel herds can support detection of epidemics. Serological surveillance can also be used to assess the increase in the number of seroconversions.

During an epidemic, surveillance should be conducted to define the extent of the epidemic area for the purpose of disease prevention and control as well as the extent of movements and trade of susceptible animals.

During inter-epidemic periods:

1. the level of virus transmission should be assessed and determined by surveillance in sentinel herds of susceptible animals;

2. monitoring of ecological and meteorological factors should be carried out.

Countries or zones adjacent to a country or zone in which epidemics have been notified should determine their RVF status through an on-going specific surveillance programme.

The Veterinary Authority should coordinate in a timely manner with public health and other relevant authorities and share information to support the surveillance outcomes, the use of public health messages to prevent human exposure and the decision-making process for the prevention and control of RVF.

nb: first adopted in 1986; most recent update adopted in 2024.