Coronavirus Infection in Calves are Different Than Covid-19

Coronavirus Family

Coronavirus is a very big family of viruses that have evolved over many years. It is true that coronaviruses are present in many species of animals and human, but they may some similarities but huge differences too. Coronaviruses can cause a variety of diseases in human and animals and in many instances, these are caused by different types of the same viruses. Broadly, there are two groups, group the one evolving from mixing of genotypes of viruses across different species such as COVID-19 and the other, like bovine coronaviruses, which are fairly stable hence belong to only one ‘serotype’. Cattle coronavirus also known as (Bovine coronavirus) is closely related to OC43 coronavirus which is the cause of ‘mild cold’ in humans. There is a strong belief that common cold in human is preceded by mild transient respiratory infections in cattle.

So, the clear answer is ‘NO’ COVID type of disease-causing virus is different, has not been known to cause disease in cattle and there is no COVID-like lethal or severe disease due to coronaviruses has been reported in cattle.

Cattle coronavirus can cause enteric disease in other species of animals

Many coronaviruses have restricted host range but the bovine can infect other animal species including wildlife. Bovine coronavirus has also been shown to infect dogs, turkeys, camel and wildlife inertly as these don’t fall sick, except mild diarrhoea but shed virus in faeces. Cattle coronavirus infects other species is also proved from the evidence of the presence of antibodies against the virus after infection.  The bovine coronavirus has also been isolated from dogs showing respiratory disease which has been shown to be similar to bovine coronavirus. Similar viruses have been isolated from human faeces suffering from mild enteric diseases but the exact association is not yet certain.  An interesting feature of the bovine coronavirus is its genetic stability.  Whereas, in avian and human corona family, genetic diversity is very common due to drift in strains and types, in bovine corona only a single serotype is recognized.

The cattle coronaviruses isolated from different species have been found to have a common nucleotide sequence and receptor-binding domain. So the answer is yes, the cattle coronavirus can cause similar disease in other animal species, but not human.

Corona-associated Enteric and Respiratory Diseases in Cattle: Corona virus-associated respiratory disease in cattle was for the first time reported in the USA in 1973.  After that several outbreaks have been reported across the world.  In cattle corona infections are expressed in three different forms:

  1. Gastro-intestinal, wherein diarrhoea and related complications such as dehydration, hypovolemia, and weakness are the major presenting signs.
  2. Haemorrhagic, wherein the major signs are related to disseminated intravascular coagulation, bleeding, etc.
  3. Respiratory, wherein the sings are coughing, upper and lower respiratory disease signs, pneumonia and associated complications. In severely immunocompromised calves the disease may involve all the three forms. Corona infections are common in young calves and adults are immune due to exposure and herd immunity.  In general, it is thought that coronavirus solely may not be the culprit but it is a complex requiring several viruses and bacteria (especially Mannheimia haemolytica).  The disease is of high economic importance as large scale morbidity results in delayed or non-availability of replacement heifers.

Enteric form of the disease is also common. For this also there is a consensus that corona alone may not sufficient but it is due to a combination of factors such as other viruses such as rota and other pathogens such as cryptosporidium and E. coli. The clinical signs are diarrhoea, dehydration, anorexia, loss in weight.  Morbidity may be high but mortality is low.  Affected calves lag behind in growth

Diagnosis: The viral presence can be detected by a PCR test. The seroconversion status can be diagnosed by ELISA test based on monoclonal antibodies.

Treatment and Control:  There is no treatment available for corona infections. Most of the calves receiving colostrum will have passive immunity but this lasts only for up to 3 weeks. The calves, therefore, remain susceptible to 3week to 3 months of age, although the more common disease is recorded in the first month after birth. Calves not fed with quality colostrum or where the farmers feed water or some other supplement as the first feed to calves are the one more prone to severe disease. Recently-infected calves from birth to 20 weeks of age shed coronavirus in faeces and nasal secretions (cough particles) but at the later stage, shedding is restricted through nasal route.  In many herds corona associated respiratory disease may assume an annual cycle affecting all ages of cattle. An important factor leading to an outbreak / new infection is the introduction of an animal in the herd.

Bovine coronavirus is not secreted in milk hence there is no chance of contracting bovine corona from milk. However, the farmers should ensure that milk is not contaminated with dung (common due to swinging of tails during milking) and dung may be voiding coronavirus in adequate concentration.

No vaccine is currently available

Control by enhancing passive immunization of calves: In farms where calf morbidity due to enteric or respiratory infections is high, the incidence can be reduced by immunizing pregnant cows which results in a high titre of antibodies against coronaviruses.  In many cases, it is recommended that a combination of the corona, rota, E. coli, and cryptosporidium hyper immunization be carried out from mid-pregnancy onwards. High antibody levels in colostrum protect the calves from enteric infections caused by these pathogens. The disease is more common in young calves that are still simple-stomach.  In these calves, the administration of colostrum 50-75 ml daily can also reduce the symptoms. There are also published reports suggesting that long-term administration of colostrum leads to protective local immunity in lungs, but the precise mechanism of action is not known.

As a general strategy, it is recommended that long-term of feeding of colostrum to calves in endemic farm could be a very practical way to prevent economic losses due to corona infections.


Read: Epidemic Curves: A Simple Investigation Tool

Dr. Abdul Samad
M.V.Sc., Ph.D. (Canada)
Dairy Consultant