Louping-ill (tick-borne encephalitis)
Wolfing-ill is a viral disease transmitted by a tick, which affects the brain and spinal cord of sheep. Its name comes from the jumping and disorderly gait of affected animals. It must be said clearly: this disease is mainly described in th...
What is it?
Wolfing-ill is a viral disease transmitted by a tick, which affects the brain and spinal cord of sheep. Its name comes from the jumping and disorderly gait of affected animals.
It must be said clearly: this disease is mainly described in the British Isles and in some regions of northern Europe, with occasional outbreaks elsewhere. It is not a common cause of nervous disorders in Maghreb sheep, and to claim otherwise would be misleading.
If this sheet exists, it is for two reasons. Firstly because the question comes up among breeders who read about tick diseases. Then and above all because when faced with a sheep that staggers or convulses, the real local leads are quite different: dizziness, enterotoxemia, listeriosis, deficiencies, poisoning, regulated infectious diseases. Confusion costs time.
Key point
This disease is not a usual cause of nervous disorders in Maghreb sheep. When faced with an animal that staggers or convulses, you must have the animal examined quickly rather than concluding alone: several of the local causes can be treated.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
A first phase of fever, often discreet, which almost always goes unnoticed and during which the animal only appears depressed.
In only some animals, the virus then spreads to the nervous system and the signs become spectacular.
Tremors of the head and muscles, at first fine then marked.
Uncertain and stiff gait, animal that staggers, crosses its limbs, falls then gets up.
Movement in disordered leaps, very characteristic and the origin of the name of the disease.
Head tilted to the side, abnormal eye movements.
Change in behavior: animal which isolates itself, which appears elsewhere, sometimes excited or on the contrary indifferent to what surrounds it.
Convulsions, paralysis, animal lying on its side which pedals and no longer gets up.
Affected animals often die within a few days; those who survive frequently have nervous after-effects.
Many infected animals never get past the fever phase and recover without anyone noticing.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
A virus is inoculated by the bite of a tick. It first multiplies in the blood, giving rise to the fever phase.
In certain animals, it crosses the barrier which protects the brain and causes inflammation of the brain and spinal cord: it is these animals which present the nervous signs.
Animals whose defenses are weakened at the same time pass this stage more easily. This is particularly the case for those who suffer from tick fever at the same time, transmitted by the same tick: the two infections combine and the picture becomes much more serious.
The tick in question needs humidity and fresh vegetation, which strongly limits the geographical distribution of the disease.
There is no treatment for the virus itself once it has reached the brain.
Living in a region where the disease and its tick are established: this is the main factor, and it does not concern most North African farms.
Grazing in wetlands, moors or undergrowth during the tick activity season.
Young or newly introduced animals, not previously exposed.
Simultaneous infection with tick fever, which weakens defenses and promotes nerve damage.
Consumption of raw milk from an infected female by young animals.
Importation of animals from an affected region without quarantine or health control.
Transmission
By tick bite, in the vast majority of cases. There is no contagion through simple contact between grazing animals.
Raw milk from an infected female goat, especially from goats, can contain the virus and contaminate lambs, kids and people who drink it. It is a well-identified route of transmission.
The virus also circulates in wildlife in the regions concerned, which maintains outbreaks independently of the herds.
The distribution of the disease follows that of the tick: humid and cool regions, mainly in the British Isles and some areas of northern Europe, with occasional outbreaks elsewhere. It is not one of the common diseases of Maghreb livestock.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
When faced with a sheep that presents with nervous disorders, the veterinarian always begins with a complete nervous examination, without presuming the disease.
It prioritizes the frequent and local causes: dizziness due to a larva in the brain, enterotoxemia, listeriosis, certain deficiencies, poisoning, damage to the inner ear, and notifiable infectious diseases which give nervous signs. Many of these diseases can be treated or controlled, hence the urgency of the examination.
He inquires about the origin of animals and their movements: a disease in a cold and humid region is only serious if the context lends itself to it.
The definitive diagnosis requires laboratory analyzes carried out on the blood or, after death, on the brain.
Examining a dead animal is particularly useful when several animals show nervous signs: it guides management for the entire herd.
In all cases, a group of animals suffering from nervous disorders warrants a declaration to the health veterinarian, because certain diseases concerned are regulated.
Treatment
There is no treatment for the virus itself: no medication makes it disappear once the brain is affected.
The care is only supportive, decided by the veterinarian: calm, relative darkness, thick bedding, water and food within reach, animal turned regularly if it no longer gets up, protection against flies and the sun.
Anti-inflammatories or anti-seizure medications may be prescribed to provide relief, without acting on the cause.
An antibiotic has no effect on a virus. It may be prescribed by the veterinarian to treat an associated infection, never as a treatment for the disease itself.
An animal that has been lying down for several days, which does not get up and no longer eats, must be the subject of an honest discussion about euthanasia in order to avoid prolonged agony.
The most important point remains the diagnosis: before concluding that it is a viral disease without treatment, the causes of nervous disorders must be ruled out, which are easily treated when intervened early.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
In regions where the disease is established, prevention is based on the fight against ticks: anti-tick products, vegetation maintenance, management of the most infested routes. This is the same lever as for all other tick-borne diseases.
Do not give raw milk from a female likely to be infected to lambs and kids in these same regions.
Apply quarantine and respect health controls when importing animals from an affected region.
For Maghreb farms, the best prevention of nervous disorders in sheep does not involve this disease: it involves vaccination against enterotoxemia, deworming of dogs and management of slaughter waste against whirling disease, a balanced diet, the quality of ensiled fodder against listeriosis, and the fight against ticks in general.
In all cases, several animals showing nervous signs at the same time justify a call to the veterinarian without delay, some of the possible causes being regulated or dangerous for humans.
Vaccination
No vaccine is available for this disease in Maghreb farms, and the question does not arise in practice since the disease is not a common cause of nervous disorders there.
A vaccine has been used in the past in affected British regions; its availability there has been irregular and it does not concern North African herds.
On the other hand, a very useful vaccine does exist against another common cause of sudden death and nervous signs in sheep, enterotoxemia. This is the one you need to talk to the vet about.
Possible complications
Permanent nervous after-effects in animals that survive: abnormal gait, tremors, animal which no longer follows the herd.
Death within a few days in established nervous forms.
Injuries, falls and drowning in animals that no longer move.
Animal lying down for a long time, with bedsores, bloating and attack by flies.
Major worsening when another disease transmitted by the same tick is added.
Delay in diagnosis of other nervous diseases of sheep, which are much more common locally and some of which can be treated: this is the most concrete risk for a North African breeder.
When to see a veterinarian
A sheep staggers, trembles, turns, tilts its head or moves in disorderly leaps: consult without delay, several possible causes can be treated if we intervene early.
An animal convulses or remains lying on its side without being able to get up: it is an emergency.
Several animals present with nervous disorders in a short time: call the health veterinarian, certain diseases concerned are subject to mandatory notification.
An animal has a fever then changes behavior in the days that follow.
Animals have been recently imported from an area where the disease is known and are showing nervous signs.
An animal dies suddenly after showing nervous signs: have it examined, this will protect the rest of the herd.
Transmission to humans
The virus can infect humans, but cases are rare and mainly concern regions where the disease is established.
Contamination occurs through the bite of an infected tick, through the consumption of raw milk from an infected animal, particularly a goat, or during the handling of contaminated animals and samples, which mainly exposes veterinarians, slaughterhouse and laboratory staff.
In humans, the infection most often manifests as a flu-like syndrome; Nerve damage is possible but rare. Any febrile condition following a tick bite warrants medical advice, reporting the bite.
Useful precautions are those that apply to all diseases transmitted by ticks: covering clothing and gloves when working among the herd, inspection of the body after a day in the vegetation, rapid removal of ticks without crushing or piercing them.
Drinking boiled or pasteurized milk remains a good general practice: it protects against this disease as well as against brucellosis and Q fever, which are very present in the Maghreb.
Prognosis
The majority of infected animals do not go beyond the fever phase and recover without anything being noticed.
In those who develop nervous signs, the prognosis is poor: many die, and survivors often have after-effects that compromise their future in the herd.
The prognosis significantly worsens when tick fever is present at the same time.
For a North African breeder, the real message is elsewhere: when faced with a staggering sheep, the common local causes often have a much better prognosis if the veterinarian is called early.
Frequently asked questions
Does this disease exist among us?
It is mainly described in the British Isles and some regions of northern Europe, where the tick that transmits it lives. It is not a common cause of nervous disorders in Maghreb sheep. When faced with an animal that is staggering, you must first think about common illnesses locally, many of which can be treated.
My sheep is staggering and shaking: what should I do?
Call the veterinarian the same day, without trying to guess the disease. Many causes of nervous disorders in sheep are well treated when intervened early, and some are reportable. Do not give anything of your own initiative while waiting.
Is there a vaccine?
No vaccine available or useful here for this disease. On the other hand, there is a very useful vaccine against enterotoxemia, which is a very real cause of sudden death and nervous signs in our livestock: this is the one you should talk to your veterinarian about.
Can I catch it from drinking the milk of my sheep or goats?
In regions where the disease is circulating, yes, raw milk is a known route of contamination, especially in goats. In our country, the risk of this disease is very low, but raw milk presents other, very real risks, such as brucellosis and Q fever. Boiling milk remains a good habit in all cases.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 10 September 2026
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