Peste des petits ruminants (PPR)
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Small ruminant plague is an animal disease of small ruminants, sheep and goats. Goats are usually more severely affected than sheep, with a large proportion of the flock often affected. Young animals are more affected by this disease than old animals. However, other cloven-hoofed animals such as domestic cattle, buffalo, and wild ruminants (e.g. deer, ibex, gazelles, antelopes) as well as the dromedary are also affected. Some of these even-toed ungulates often do not show symptoms of disease (e.g., domestic cattle); however, they may shed the virus. In Mongolia, a disease outbreak with high mortality occurred in saiga antelopes in 2017. In pigs, the disease, which is asymptomatic, has only been detected in experimental infection trials. Small ruminant plague is characterized by high morbidity and mortality especially in countries with first occurrence. It causes high economic losses as the herd has to be culled when infected. Infected carcasses must be destroyed and, like raw milk products from infected animals, must not be traded. The FAO and the OIE are striving to eliminate the disease by 2030. The causative agent of small ruminant plague is the Peste de Petits Ruminants virus (PPRV), a paramyxovirus (genus Morbillivirus), which is genetically closely related to the causative agent of rinderpest, the rinderpest virus (RPV). Although there is antigenic similarity to RPV, PPRV can be clearly distinguished from it. The serotype PPRV splits into 4 different genotypes (I-IV).
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 regular outbreaks in Turkey; last outbreak: 2011-2016. In Europe, an occurrence has been reported for the first time in Bulgaria in June 2018.
Transmission is mainly through close direct contact with infected animals or their excreta, but can also be aerogenic via the respiratory tract. Viral excretion is possible before the expression of clinical signs. It occurs via lacrimal fluid, nasal and pharyngeal secretions and faeces. The urine and saliva of goats also contain virus. Clinically inapparently infected animals (e.g. domestic cattle, but also wild ruminants) serve as virus reservoirs. 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 documented based on scientific studies (outbreak in Bangladesh 2012-2015).
Goat and sheep, cattle, pig, wild ruminants are susceptible. Small ruminant plague is usually more dramatic in goats than in sheep, leading to death in about 90% of goat kids. In cattle and in some wild ruminants, the virus causes subclinical disease. High morbidity and variable mortality are typical of PPR. The general mortality rate varies between 10 and 90%. The incubation period is 4-5 days, after which, from day 6, high fever is observed. A prodromal phase and an erosive phase can be distinguished. The prodromal phase, which mainly shows symptoms of a general disease, may last 3 days and may be accompanied by ulcerative-necrotizing inflammation in the oral cavity and gums. Affected animals usually show high fever 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 mucous membrane of the mouth develop. Erosions can sometimes be detected throughout the gastrointestinal tract (often with a striated pattern "zebra stripes"). Occasionally, pneumonia also occurs. It is characterized by bronchointerstitial pneumonia with evidence of viral cytoplasmic inclusion bodies and syncytia. In highly susceptible animals, both acute and peracute forms of the disease occur, leading to death shortly after the prodromal phase. Conversely, there is also a chronic form of progression, which is usually triggered by weakly virulent viruses. It causes barely visible lesions to highly pronounced nodular proliferations in the mouth area. Due to the outbreak in Bulgaria, even in the case of similarly occurring individual symptoms, a laboratory diagnostic examination by means of exclusion diagnostics or, in the case of suspicion, a suspicion referral via the official veterinarian is indicated. Since the disease has never occurred in Austria and the symptoms are hardly known, a diagnosis by exclusion is also indicated in case of occurrence of single symptom-like changes 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, labial rhinitis, foot-and-mouth disease, bluetongue, contagious caprine pleuropneumonia, pasteurellosis, salmonellosis, coccidiosis.
Entry into the stable should be prohibited to strangers with the exception of the veterinarian. Pets (dogs, cats) should also be prevented from entering. Strict hygiene and biosecurity measures apply to all persons entering the stable - these must be observed at all costs. As a preventive measure, no foreign animals whose health status is not known should be immediately introduced into the herd. A quarantine of 3-4 weeks, as well as inquiring about a possible disease occurrence in the herd of origin, can significantly reduce the risk of disease introduction into the herd. The spread and transmission of PPR through animal traffic in regions with non-vaccinated animal populations played a major role in Turkey. There is currently no vaccine licensed in Europe to control the disease. Live attenuated vaccines (e.g. based on strain Nigeria-75) are used outside Europe (e.g. in Turkey) in areas with endemic distribution. In Turkey, vaccination coverage (2010-2012) in young animals ranged from 65% to 76%. Intensive research into suitable vaccines is currently underway.
Virus detection can be performed 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.
Specimen for live animals:
- Swab samples of nasal, ocular, and pharyngeal secretions (no bacteriological swab specimens).
- Blood (EDTA/heparin) and serum
Samples from dead animals:
- Whole animal carcasses or organs such as.
- Lymph nodes (especially mesenteric lymph nodes)
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
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Last updated: 02.02.2022