The plague of small ruminants (peste de petits ruminants, PPR) is a highly contagious, acute, highly febrile viral infection of sheep and goats. Occasionally, other cloven-hoofed animals also contract the disease. Humans cannot become infected.

Small ruminant plague is endemic in Africa, the Middle East, Central, Central and East Asia. There are regular outbreaks in North Africa and Turkey. In Europe, the first outbreak was reported in Bulgaria in June 2018.

Sheep and goats, but also domestic cattle, buffalo, wild ruminants (e.g. deer, stone deer, gazelles, antelopes), dromedary, pigs. Domestic cattle and buffalo are susceptible, but they do not excrete the virus and show no symptoms of the disease. However, seroconversion does take place.

Mainly through close direct contact with infected animals or their excreta, also via the air (aerogenic)

4 to 5 days

High fever (40 to 41.5 °C), anorexia, constipation, nasal and eye discharge, severe diarrhoea, pneumonia, weight loss, loss of fertility, reduced milk production, death

There is no therapy

There is currently no vaccine licensed in Europe to control the disease.

The plague of small ruminants has never occurred in Austria.

Small ruminant plague is an animal disease of small ruminants, sheep and goats. Goats are usually more seriously affected than sheep, with a large proportion of the herd often affected. Young animals are more severely affected by this disease than older animals. However, other cloven-hoofed animals such as domestic cattle, buffalo, wild ruminants (e.g. deer, stone deer, gazelles, antelopes) and dromedaries are also affected. Some of these even-toed ungulates often show no symptoms of the disease (e.g. domestic cattle). Domestic cattle and buffalo do not excrete the virus, but seroconversion does take place. Wild ruminants and dromedaries can excrete virus. In Mongolia, there was a disease outbreak with high mortality in saiga antelopes in 2017. Experimental infection trials have shown that European pigs are susceptible to this virus, show clinical signs of the disease and are capable of transmitting the disease to small ruminants with which they come into contact.

Small ruminant plague is characterised by high morbidity and mortality rates (90 to 100 % are possible), especially in countries where it first occurs. It causes high economic losses, as the herd has to be culled if infected. Infected carcasses must be destroyed and, like raw milk products from infected animals, may not be traded.

The causative agent of small ruminant plague is the Peste de Petits Ruminants virus (PPRV) or Small Ruminant Morbillivirus (SRMV), a paramyxovirus (genus Morbillivirus), which is genetically closely related to the causative agent of rinderpest, the Rinderpest virus (RPV). Although there is an antigenic relationship to RPV, PPRV can be clearly distinguished from it. The PPRV serotype is divided into 4 different genotypes (I-IV).

Occurrence

The plague of small ruminants is endemic in Africa, the Middle East, Central, Central and East Asia. PPRV lineage IV has recently spread widely in Asia (e.g. China, Nepal, India, Pakistan) and Africa (from the north to Tanzania). There are outbreaks in Turkey every year (2005-2024). In Europe, the first outbreak was reported in Bulgaria in June 2018.

Transmission

Transmission mainly occurs through close direct contact with infected animals or their faeces, but can also occur aerogenically via the respiratory tract. Virus excretion is possible before the development of clinical symptoms. It occurs via the lacrimal fluid, nasal and pharyngeal secretions and faeces. The urine and saliva of goats also contain viruses. The virus can be detected in the faeces of goats up to 2 months after recovery. Animals that survive PPR infections are immune to reinfection as well as to other genotypes.

Transmission of PPRV via raw milk from goats has been proven on the basis of scientific studies (outbreak in Bangladesh 2012-2015).

There is no vertical transmission of PPRV via the placenta.

Symptomatology

Goats and sheep, cattle, pigs, wild ruminants are susceptible. The plague of small ruminants is usually more dramatic in goats than in sheep and leads to death in 100% of goat kids (older than 4 months, which are no longer protected by maternal antibodies). In cattle and some wild ruminants, the virus causes a subclinical disease. High morbidity and variable mortality are typical for PPR. The general mortality rate varies between 10 and 90 %.

The incubation period is 4-5 days, after which, from the 6th day onwards, high fever is observed. A distinction can be made between a prodromal and an erosive phase.

The prodromal phase, which predominantly shows symptoms of a general illness, can last 3 days and can be accompanied by ulcerative-necrotising inflammation in the oral cavity and gums. The affected animals usually show a high fever of between 40 and 41.5 °C. Other important clinical manifestations are anorexia, constipation, serous nasal and ocular discharge, severe diarrhoea and pneumonia. The watery nasal and ocular discharge causes crusts to form on the eyes and nostrils.

At the beginning of the erosive phase, erosions, ulcers and necrosis of the oral mucosa develop. Erosions can sometimes be detected in the entire gastrointestinal tract (often with a stripe-like pattern "zebra stripes"). Occasionally, pneumonia also occurs. It is characterised by bronchointerstitial pneumonia with evidence of viral cytoplasmic inclusion bodies and syncytia.

In highly susceptible animals, both acute and peracute forms occur, leading to immediate death shortly after the prodromal phase. Conversely, there is also a chronic form, which is usually triggered by weakly virulent viruses. It causes barely visible lesions to very pronounced nodular proliferations in the mouth area.

Due to the outbreak in Bulgaria, a laboratory diagnostic examination via the exclusion diagnostics or, in the case of suspicion, a suspicion dispatch via the official veterinarian is also indicated in the case of similarly occurring individual symptoms. As the disease has never occurred in Austria and the symptoms are hardly known, a diagnosis of exclusion is also indicated if individual symptom-like changes occur in the herd.

Differential diagnosis: All erosive or vesicular skin and mucous membrane diseases of ruminants with severe disturbance of the general condition, e.g. sheep and goat pox, cold sores, foot and mouth disease, bluetongue, contagious caprine pleuropneumonia, pasteurellosis, salmonellosis, coccidiosis.

Preventive measures

With the exception of the vet, unauthorised persons should not be allowed to enter the barn. Pets (dogs, cats) should also be prevented from entering.
Strict hygiene and biosecurity measures apply to all persons entering the barn - these must be strictly adhered to.
As a precautionary measure, no foreign animals whose health status is not known should be introduced into the herd immediately. A quarantine period of 3-4 weeks, as well as enquiring about possible disease in the flock of origin, can significantly reduce the risk of disease being introduced into the flock. The spread and transmission of PPR through animal traffic in regions with non-vaccinated animal populations played a major role in Turkey.

The FAO and WOAH are endeavouring to eliminate the disease by 2030. There is currently no vaccine authorised in Europe to combat the disease. Live attenuated vaccines (e.g. based on the Nigeria-75/1 strain) are used outside Europe (e.g. in Turkey) in areas where the disease is endemic. Currently, all newborn and unvaccinated adult small ruminants are vaccinated annually in Turkey. Seroconversion rates were 93% in 2018 and 84% in 2020.

Virus detection can be carried out early after infection, from highly febrile animals and animals with incipient mucosal lesions. Samples for serological testing can be taken as early as 6 days after infection.

Sample for live animals:

• Swab samples of nasal, eye and throat secretions (no bacteriological swab transport media)
• Blood (EDTA/heparin) and serum

Samples from dead animals:

• Whole animal carcasses or organs such as.
• Lymph nodes (especially mesenteric lymph nodes)
• spleen
• lungs
• intestine

Sample transport and short-term storage at +4 °C

Detection methods:

• Direct virus detection: molecular biological methods, virus isolation
• Indirect virus detection (antibody detection): ELISA