Virus-induced congenital malformations in cattle

Abstract

Diagnosing the cause of bovine congenital malformations (BCMs) is challenging for bovine veterinary practitioners and laboratory diagnosticians as many known as well as a large number of not-yet reported syndromes exist. Foetal infection with certain viruses, including bovine virus diarrhea virus (BVDV), Schmallenberg virus (SBV), blue tongue virus (BTV), Akabane virus (AKAV), or Aino virus (AV), is associated with a range of congenital malformations. It is tempting for veterinary practitioners to diagnose such infections based only on the morphology of the defective offspring. However, diagnosing a virus as a cause of BCMs usually requires laboratory examination and even in such cases, interpretation of findings may be challenging due to lack of experience regarding genetic defects causing similar lesions, even in cases where virus or congenital antibodies are present. Intrauterine infection of the foetus during the susceptible periods of development, i.e. around gestation days 60–180, by BVDV, SBV, BTV, AKAV and AV may cause malformations in the central nervous system, especially in the brain. Brain lesions typically consist of hydranencephaly, porencephaly, hydrocephalus and cerebellar hypoplasia, which in case of SBV, AKAV and AV infections may be associated by malformation of the axial and appendicular skeleton, e.g. arthrogryposis multiplex congenita. Doming of the calvarium is present in some, but not all, cases. None of these lesions are pathognomonic so diagnosing a viral cause based on gross lesions is uncertain. Several genetic defects share morphology with virus induced congenital malformations, so expert advice should be sought when BCMs are encountered.Electronic supplementary materialThe online version of this article (doi:10.1186/s13028-015-0145-8) contains supplementary material, which is available to authorized users.

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

“…Akabane is an insect-transmitted virus that causes congenital abnormalities of the neurological system in ruminants and one of the most potent teratogen viruses affecting cattle, sheep and goats [29,83]. The incidence of Akabane virus-induced disease is influenced by the species and time of gestation at which infection occurs [29] and by the strain of the virus.…”

“…Akabane is an insect-transmitted virus that causes congenital abnormalities of the neurological system in ruminants and one of the most potent teratogen viruses affecting cattle, sheep and goats [29,83]. The incidence of Akabane virus-induced disease is influenced by the species and time of gestation at which infection occurs [29] and by the strain of the virus. Infection in adult cattle has usually no specific signs while infection of pregnant cattle often causes foetal damage, resulting in abortion, stillbirth or various congenital abnormalities [84][85][86].…”

“…In cattle, most infections are unapparent [20,21]; however, a few animals may develop clinical signs that include fever, salivation, facial oedema, lesions on lips and nostrils, ulcerations in the oral and nasal mucosa, including tongue and gingiva, and coronitis [29,30]. In utero transmission occurs in cattle and can result in birth of viraemic calves, abortion, congenital defects such as cerebellar hypoplasia, hydranencephaly or porencephaly accompanied with behavioural abnormalities (head pressing, ataxia, inability to stand and suck well, dullness, disorientation and impaired vision)and congenital musculoskeletal deformities (agnathia, brachygnathia and arthrogryposis) [29][30][31].…”

“…Although clinical presentations depend on several factors, such as on strain of virus, species of host, immune status of host, reproductive status of host, age of host, concomitant infections and time of gestation [49], BVD virus is known to produce from subclinical infections (persistently infected animals) to a large number of diverse diseases, including reproductive disorders (decrease in conception rate and pregnancy rate, increased embryonic mortality), early embryonic death, foetal reabsorption abortion, stillbirths, central nervous system defects (microencephaly, cerebellar hypoplasia, hydranencephaly, hydrocephalus, hypomyelinogenesis, hypomyelination, cerebellar-ocular agenesis, ocular abnormalities), ocular abnormalities (microphthalmia, cataracts, retinal degeneration, optic neuritis), musculoskeletal deformities (brachygnatism), thymic aplasia, hypotrichosis, alopecia, pulmonary and renal hypoplasia [29,50], growth retardation [29], enteritis and mucosal disease [51][52][53]. The most dramatic clinical symptoms are associated with the peracute form of the disease that is characterized by a sudden decrease in milk production, fever, watery and bloody diarrhoea, dehydration, tenesmus, tachypnea, tachycardia, drooping ears, anorexia, excessive lacrimation, nasal discharge, hypersalivation, petechial and ecchymotic haemorrhages of the visible mucosa, and development of ulcers of the nares, muzzle, lips and oral cavity [54] mucous membranes as well as skin lesions around the inguinal and perineal regions, the inner thighs and inside the ears [55].…”

The chasm between public health and reproductive research: what history tells us about Zika virus

“…Vertical transmission of hepatitis C virus, a virus of the Hepacivirus genus, from mother to child is known to occur in up to 10 % of pregnancies. BVDV, a member of the Pestivirus genus, does not infect humans but is known for its vertical transmission in cattle [1][2][3][4][5]. BVDV infection at different stages of gestation may lead to a spectrum of adverse pregnancy outcomes, including pregnancy loss and neurologic manifestations (including deformations such as hydrocephalus and microcephaly) in the offspring.…”