79. Diseases caused by Orthobunyaviruses (Zoon.).

Question 1

Bunyaviridae family?

Answer 1

Bunyaviridae family

• Genera: Orthobunya, Phlebo, Nairo, Hantavirus genus - more than 300 sp. mainly in tropics
• Peribunyaviridae - Orthobunyavirus: Aino and Akabane disease, Schmallenberg disease
• Virus Morphology
• Segmented (3), ssRNA genoma, helical capsid, enveloped
• Resistance: sensitive to high temperatures, disinfectants and detergents
• Biological properties: arboviruses (except Hantavirus) ➝ mainly mosquito or tick vectors

- Zoonosis

• Antigenicity

• Envelope glycoproteins ➝ good antigens
• Genetic similarities within genera: serogroups, cross-reactions

• Diagnosis

• Direct: virus isolation, IF, HA
• Indirect: VN, ELISA, HAI

Question 2

Akabane and Schmallenberg disease Epidemiology?

Answer 2

Akabane and Schmallenberg Disease

Epidemiology

• Vertebrate hosts

• Amplifier hosts or reservoirs: small rodents, birds, domesticated animals
• Dead-end hosts (humans)
• Arthropod vectors: biological sectors and transovarial transmission
• Simbu serogroup: Asia, Australia, Africa, Europe, North and South America
• Vector: biting midges
• Reservoirs: birds
• Suffer from disease: cattle, sheep, swine
• Akabane virus: Asia, Africa, Australia, Israel, Turkey ➝ cattle, sheep, goat ➝ abortion, foetal development problems
• Aino virus: Japan, Australia ➝ cattle, sheep ➝ abortion, foetal defects
• Schmallenberg virus: Europe ➝ cattle, sheep ➝ abortion, foetal defects

Question 3

Akabane disease?

Answer 3

Akabane disease

• Occurrence: Asia, Africa, Australia, Middle East, Turkey, Cyprus
• Vector: Culicoides spp.
• Suffers from disease: cattle, sheep, goat (buffalo, wild ruminants, camel, horse, African swine species)
• Pathogenesis, clinical signs, pathology
• Mosquito bite ➝ few days incubation ➝ viraemia for 4-5 days
• Adults: subclinical seropositivity, if more virulent strain ➝ fever, encephalomyelitis (CNS signs), increased deaths
• Pregnant individuals: infects foetus ➝ abortion, miscarriage, premature birth, foetal arthrogryposis, hydroencephaly, muscle dystrophy
• Diagnosis: clinical signs, pathology, laboratory methods (PCR, isolation, VN, HAI)
• DD: Aino (Japan, Australia), ephemeral fever, Ibaraki disease, bluetongue, Japanese encephalitis, BVD (lab investigations)
• Prevention
• Mosquito control
• Asia, Australia: inactivated vaccines

Question 4

Schmallenberg disease (SBV) info and epidemiology?

Answer 4

Schmallenberg disease (SBV)

• Dairy cows: increased BT, impaired general condition, anorexia, reduced milk yield ➝ signs disappeared after few days
• Epidemiology
• Occurrence: Europe
• Vector: Culicoides spp. ➝ seasonal in summer, autumn
• Transmission by infected foetus (transport of pregnant animals) so can spread to long distances
• Suffers from disease: cattle, sheep, goat

Question 5

Pathogenesis of Schmallenberg disease?

Answer 5

Pathogenesis

• Mosquito bite ➝ 2-4 days incubation ➝ viraemia 3-6 days
• Non-pregnant: no clinical signs
• Pregnant + seropositive: no abortion but maternal immunity in newborns
• Pregnant + not seropositive: congenital disorders, abortion

‣ Sheep: between PD30-50 ➝ congenital disorders, abortion

‣ Cattle: first 3 months ➝ brain and spinal cord defects, after PD100 ➝ joint and muscle defects, after 6th month ➝

immunocompetence ➝ only mild defects

Question 6

Clinical signs of Schmallenberg?

Answer 6

Clinical signs

• Cattle: fever (40.5 ℃), anorexia, diarrhoea, poor condition, reduced milk yield (50%), congenital disorders rarely seen
• Sheep: fever (40.5℃), congenital disorders

‣ Lambs are mainly born at 135-151 days (normal is 147)

‣ Lambs are sometimes born alive, mostly not viable

‣ Several breeds: Suffolk, Texel, Blue Texel, Dairy, Flevolander, Swifter, Blessumer, cross-breeds

‣ Arthrogryposis, hydranencephaly, ankylosis, torticollis, scoliosis, brachygnatia, cerebellar hypoplasia and aplasia,

enlarged thymus

Question 7

Diagnosis, public health considerations and measures legal action for schmallenberg disease?

Answer 7

• Diagnosis

• RT-PCR: isolation on KC (mosquito) and BHK-21 cells (+IF)
• Virus neutralisation and indirect immunofluorescence test (iIF)

• Public health considerations

• Potentially zoonotic
• Unlikely, no human cases reported ➝ low risk

• Measures, legal actions

• EC ➝ further studies necessary
• OIE recommendations
• Some EU member states: spontaneously implemented suspicion-reporting procedures for abortions, stillbirths and congenital

malformations in ruminants

• Import restrictions

‣ Ban on Dutch breeding heifers: Russia, Ukraine, Morocco, Egypt, Algeria, Jordan

‣ Ban on bovine semen and bovine embryos from Netherlands: USA, Japan, Argentina, Kazakhastan, Morocco, Ukraine,

Russia

Question 8

Crimean Congo haemorrhagic fever?

Answer 8

• Crimean-Congo haemorrhagic fever

• Etiology: CCHV, Nairoviridae, Orthanairovirus
• Occurrence: Africa, Asia, Middle East, South Europe, sporadic seropositivity in Hungary
• Vector: tick (Hyalomma) ➝ seasonal, biological vector, transovarial spread
• Susceptible species: Domestic and wild ruminants, rodents ➝ asymptomatic, zoonosis
• Human: damages blood vessel endothel cells and hepatocytes ➝ fever, headache, muscle pain, haemorrhages in skin and

mucosa, bloody urine and faeces

• Mortality: 30-50%
• Diagnosis: clinical signs, presence of ticks, seasonality, lab investigation (RT-PCR, isolation, serology: VN, HAI)
• Treatment: Supportive + Ribavirin
• Prevention: avoid tick bite, protective clothes, no vaccine

Question 9

Hantavirus-associated diseases?

Answer 9

Hantavirus-associated diseases

• Hantaviridae: Hantaan, Korea
• Reservoirs: Apodemus agrarius, A. flavicollis, mouse, rat, hamster, other small mammals
• Zoonosis ➝ haemorrhagic fever and renal syndrome in human
• Shedding: urine, faeces, saliva
• Airborne infection and viraemia
• Clinical signs

‣ Rodent reservoir ➝ no disease, pathology and histopathology negative

‣ Human ➝ fever, headache, muscle pains, haemorrhages (skin, hemoptysis, hematuria, hematemesis, melon), proteinuria,

20% shock, serious haemorrhage, nephrosis, pulmonary form in USA

• Pathology, Histopathology: peritoneal oedema, myocardial haemorrhage, hyperaemic kidneys, haemorrhage, necrosis ➝

haemorrhage and necrosis in frontal hypophysis

• Diagnosis: RT-PCR, virus isolation, serology: ELISA, IF
• Treatment, Control: symptomatic treatment

‣ Infected pet rodents: stamping out, regular control of breeders

‣ Avoid contact with wild rodents

Question 10

Severe fever and thrombocytopenia syndrome(SFTS)?

Answer 10

Severe fever and thrombocytopenia syndrome (SFTS)

• Phlebovirus
• Asia (China, Korea, Japan), Europe mediterranean countries, USA
• Zoonosis
• Tick vector: Haemaphysalis longicornis, Rhipicephalus microplus
• Sheep, goat, cattle, horse, dog, cat, human (without tick too)
• Animals ➝ symptomatic infection
• Human ➝ fever, thrombocytopenia, leukocytopenia, enteric symptoms, liver enzyme elevation, blood lab value changes