Akabane Virus

Natural Intrauterine Infection with Schmallenberg Virus in Malformed Newborn Calves

“…Mechanistic hypotheses that could explain these alterations are discussed in online Technical Appendix 6 (http://wwwnc.cdc.gov/EID/article/20/8/12-1890-Techapp6.pdf). Similar to the situation with Akabane virus infection (8), the clinical picture shown by in utero SBV-infected newborn calves is likely to depend largely on the age of the fetus at the time of infection. The infection must be quickly contained if the fetus is infected when immunocompetent (>120-150 days after conception), and we deduce that damages inflicted by the virus consequently have no or little effect on its further development.…”

Encephalomyelitis Associated with Akabane Virus Infection in Adult Cows

“…19 AV has a tropism for motor neurons in the spinal cord, as detected through immunohistochemistry, and causes neurogenic skeletal muscle atrophy or dysplasia that is believed to be the cause of the lameness and locomotor problem exhibited by these cows. 4 Severe muscular atrophies were observed in two cows examined.…”

“…However, during the early and mid to late gestation periods infection results in abortion and congenital arthrogryposis-hydranencephaly syndrome (AHS), respectively. 4,10 Although nonsuppurative encephalomyelitis may be observed in the late gestation infection in calves without AHS, encephalomyelitis induced by AV is unusual in cattle after birth. A few case of this condition caused by a highly virulent AV strain known as Iriki strain were reported in Japan and Taiwan, suggesting that AV may cause nonsuppurative inflammation in the brain and spinal cord of cows through horizontal rather than vertical transmission.…”

Epidemiology and Emergence of Schmallenberg Virus Part 1: Origin, Transmission and Differential Diagnosis

“…The most severe defects are seen after susceptible cows have been infected in earlier gestation. Infection during organogenesis may substantially disrupt structural development in target organs [87] causing arthrogryposis [88], and sometimes also torticollis, kyphosis and scoliosis [29,84] with associated neurogenic muscle atrophy due to depletion of spinal ventral horn motor neurons, a loss of axons, and depletion of myelin in the lateral and ventral tracts [89]. Calves infected late in pregnancy may be born alive but unable to stand and may have a flaccid paralysis of the limbs, or may be incoordinated and on necropsy show a disseminated encephalomyelitis [90].…”