With the arrival of autumn rains combined with temperatures exceeding 20°C, the proliferation of insects, particularly the Culex mosquito, increases, with an increase in its breeding sites.

This mosquito is the vector for transmission of the West Nile virus between birds (migratory and sedentary), which act as reservoirs for the virus.

Also, the mosquito harboring the virus transmits it by bite to humans, causing flu-like symptoms, and to other domestic mammals, including horses, causing fever and nervous disorders.

These accidental hosts are epidemiological dead ends for the disease and therefore do not contribute to the spread of the virus, and there is no transmission of the virus between humans or horses.

In Tunisia, West Nile fever has been diagnosed in humans and horses since 2003. In recent years, the disease has been confirmed by laboratories in humans and horses (the latest in 2024), with cases of mortality or sequelae of nervous system damage.

West Nile fever is a notifiable disease that does not place the horse in isolation or quarantine the stable.

How to recognize the disease

"My horse is behaving strangely" including:

- Ataxia (impaired coordination of movements) and locomotor difficulties that can lead to paralysis,

- Depression or, conversely, hyperexcitability, as in rabies, but without hypersalivation. This is why West Nile fever is often diagnosed in the laboratory after rabies is suspected,

- Muscle tremors,

- Hyperthermia (temperature > 38.5°C) and a decline in general condition.

Cases recover within 20 to 30 days, with sequelae that can persist for up to 6 months after infection.

How to combat this disease

The vaccine against this disease has proven effective in countries where it is marketed, which is not the case in Tunisia.

Other preventive measures are employed and consist of minimizing horses' contact with mosquitoes during high-risk periods (i.e., summer and autumn):

- Bring horses inside closed buildings before the end of the day and take them outside after dawn (i.e., outside periods of peak mosquito activity).

- Place mosquito nets at the entrances to stables.

- Natural or dynamic ventilation of stables,

- Avoid lighting the boxes and the stable,

- Install insect traps in stables and/or the surrounding environment and use larvicidal insecticides,

- Eliminate migratory bird nests, place chicken coops and ornamental birds away from stables,

- Use repellents on horses, while changing the molecules to prevent insect resistance.

- Limit stagnant water as much as possible (tarpaulins, ruts, trampling areas, flowerpots, tires, etc.).

- Clean water troughs regularly.

- Install a full, fine-mesh mosquito net cover impregnated with a repellent product.

The Fédération Equestre Internationale (FEI) is launching the Equine Out-of-Competition Anti-Doping Testing in 2026 as part of its commitment to promoting fairness, equine welfare, and excellence, both in and out of competition.

The Equine Out-of-Competition Anti-Doping Testing apply to all FEI disciplines, with Endurance being the first to be implemented.

In 2026, a number of endurance horses will be selected to be part of a Testing Pool. These horses will take part in targeted anti-doping testing, and their registered Trainers will need to keep the FEI updated on the horses’ locations at all times—this is known as Whereabouts Information. This information allows the FEI to locate the horses whenever needed and carry out testing without advance notice.

A newly developed feature "Whereabouts App" of the existing FEI HorseApp will support the process of Whereabouts Information submission.

A “How To” page on the use of the Whereabouts App will be provided to the registered Trainers upon notification that their horse(s) has been placed into a Testing Pool.

A user guide for the application will be made available to registered trainers as soon as they are notified that their horse(s) have been included in a test group.

For more information, the FEI has prepared a FAQ document explaining on the Equine Out-of-Competition Anti-Doping Testing, related Whereabouts requirements, and the consequences of non-compliance with these requirements, relevant legal provisions can be found in the Equine Anti-Doping and Controlled Medication Regulations.

The FEI has published the new System of Education for Officials in the disciplines of Show Jumping, Endurance and for Veterinarians, which will come into effect on 1st December 2025.
For more details, click HERE.

New mandatory fitness-to-compete checks by the Ground Jury, in consultation with the Veterinary Delegate, in all cases of blood. For more details, click HERE.