Avian influenza in cattle, questions and answers
Updated 29.8.2024.
In spring-winter 2024, influenza cases were reported in goats and cattle in the USA. ETT has compiled a list of frequently asked questions and answers. The page will be updated as necessary.
Why is avian influenza being closely monitored and studied in different animal species?
Apart from the fact that avian influenza can cause severe disease and high mortality in many different animal species, the disease has for years been transmitted sporadically from animals to individual humans. The threat of mammalian infections is that the virus is more easily transformed in mammals to infect other mammals. The virus’ mutation is being closely monitored around the world to avoid it becoming the cause of a potential human pandemic.
Which pathogen causes avian influenza in cattle?
In the spring of 2024, avian influenza infections were detected in cattle (dairy cows) in the USA. This is the influenza A virus H5N1, known as highly pathogenic avian influenza (HPAI), which is a subtype of the virus that causes the disease in cattle in the USA, but which has not yet been detected in Europe.
To which other animal species can the avian influenza virus found in cattle be transmitted?
In the USA, the avian influenza virus that causes the disease in cattle has so far infected at least poultry, newborn goats, cats and alpacas.
In addition to these domestic species, infection has also been found in many wild mammal species.
Is the virus found in cattle in the USA the same as the virus that caused the epidemic in fur animals in Finland?
The highly pathogenic avian influenza virus H5N1 has caused an outbreak of avian influenza in farmed fur animals in Finland in 2023, but this virus is of a different subtype to the virus found in cattle in the USA.
The subtype of the virus that caused the disease in cattle in the USA has not yet been found in Europe, in wild birds or in other animal species.
Where did the disease originally spread to cattle?
In the USA, the disease is suspected to have been transmitted to cattle originally from wild birds. It is considered more likely that the disease was transmitted from birds to cattle on a single occasion and started to spread between cows than that it was transmitted to multiple herds by wild birds.
How is avian influenza transmitted in cattle?
The avian influenza virus is transmitted from one bovine to another. The route of transmission has not yet been established with certainty. However, the virus is excreted in high concentrations in milk and milk is considered effective vector of the virus, e.g. via milking machines. Equipment and people can also spread the disease. So far, no significant amounts of virus has been detected in the respiratory tract of cattle in the USA and respiratory infection is unlikely to be the primary source of infection.
Can avian influenza be transmitted from cattle to poultry?
In the USA, an outbreak of avian influenza has been found to have spread from a cattle farm to a poultry farm.
Has avian influenza been detected in calves or beef cattle?
So far, no cases of avian influenza have been reported in calves or beef cattle in the USA. In addition, studies suggest that older cows are more susceptible to the disease than younger cows.
What symptoms have been observed in cows with avian influenza?
Reduced appetite has been observed in cows. Cows may be apathetic, feverish and dehydrated. Cows may have loose stools. In heavily infected animals in particular, the virus infection is likely to cause changes in milk composition (milk thick and yellowish in colour, colostrum-like) and sometimes a complete cessation of milk production in the individual.
At farm level, a decrease in milk production has been observed. In cattle, no increased mortality has been reported in relation to avian influenza infection. However, cattle sometimes have to be culled from herds because their milk production may not return to normal. Higher than normal numbers of abortions have also been recorded on infected farms.
Can cattle recover from avian influenza?
Sick animals usually recover within 7-10 days. If necessary, they are given supportive treatment, there is no actual medication. No increased mortality has been observed in affected cattle.
Can the avian influenza virus in cattle be transmitted to humans?
In the USA, four human cases have been reported so far, all of which have been in contact with infected cattle. Three infected people have been diagnosed with eye infections, symptoms have been mild. Respiratory symptoms have been reported in one person. All patients have recovered from the disease. In 2024, nine people involved in poultry culling in the USA were also found to be infected. Their symptoms have also been mild. The infection has not yet spread from human to human.
The use of personal protective equipment is recommended for those working with affected cattle.
Can humans get avian influenza infection from milk?
In the affected cattle, the virus is excreted heavily in the milk. For this reason, the use of raw milk or cheese made from it is not recommended. Pasteurisation has been shown to destroy the virus, so that it can no longer cause the disease. Pasteurised milk is fit for human consumption and cannot be used to transmit the virus.
Can humans get avian influenza from beef?
So far, the virus has not been found in beef sold in the USA. However, meat from affected animals has not been used for human consumption.
Can calves be given milk from infected cows?
Affected animals excrete the virus heavily in milk. For this reason, on USA farms where infection has been confirmed, it is recommended to heat the milk used for calves. Heating (above 70 degrees Celsius) destroys the virus.
Can cattle be allowed to graze in Finland?
In Finland, cattle can be allowed to graze. The risk of disease is currently considered low in Finland. Routine disease control and removal of dead wild birds from pastures are currently considered sufficient precautions. If at any stage the risk of disease is found to be elevated, the authority may, if necessary, make recommendations, for example on grazing.
How is avian influenza in cattle being monitored in Finland?
At present, avian influenza in cattle is not monitored by sampling in Finland. Sick animals can be sampled for avian influenza.
What should I do if my cattle get sick and I don’t know why?
If animals become ill, the cause of their illness must be determined by a veterinarian and any necessary samples. If the symptoms may be suggestive of avian influenza, the veterinarian may also take samples from the animals for avian influenza testing. According to the Finnish Food Authority guidance, sampling may be carried out if the symptoms of the animals give reason to suspect avian influenza and the holding is located in an area where cases of avian influenza HPAI have been detected and, in addition, the epidemiological situation justifies the examination of the bovine animals.
What should I do if I suspect my cattle are infected with avian influenza?
If a producer suspects that his cattle are infected with avian influenza, he must inform the municipal veterinarian. Avian influenza is a notifiable animal disease in cattle and the producer must notify the municipal veterinarian of the suspicion no later than the next working day. The municipal veterinarian shall inform the provincial veterinarian. In the event of suspicion, samples are taken from the animals on the holding for testing for avian influenza.
What happens if my farm is found to be infected with avian influenza in cattle?
If avian influenza is detected on a farm, the authorities can make recommendations on how to operate the farm.
The authorities are constantly assessing the situation regarding the risk of avian influenza in cattle and are taking decisions on possible recommendations and actions based on the presumed risk of infection on cattle farms. Therefore, the situation regarding recommendations and possible regulations may change as the risk of disease increases.
What guidelines have been issued by the authorities in the USA to prevent the spread of the disease?
Veterinarians and producers have been urged to pay attention to good disease protection. Sick animals should be isolated and tested for the avian influenza virus. Animal movements should be minimised. A 30-day quarantine is recommended for new animals entering the farm.
As of April 2024, an administrative order has required dairy cows to be tested for avian influenza prior to interstate movement. The test result must be negative. If the test is positive for avian influenza, the cattle may not be moved. Cattle may be kept in isolation for 30 days if desired and then retested. If the re-test result is negative, the cattle may be moved.
Positive test results are always reported to the authorities. If bovine animals intended for movement test positive, an epidemiological inquiry is carried out at the holding. Several states have also imposed their own restrictions on cattle movements.
The USA regulation is currently only in force for dairy cows, but it is possible that new research suggests that it could be extended to other cattle. There are no plans for mandatory testing other than for movements. The order has been issued because of the high excretion of the virus in milk and the results of research indicating that the virus has been spread by the movement of dairy cows. After interstate movement, a 30-day quarantine period is recommended for cows in the new holding area.
Is the government financially supporting producers in the USA because of the production losses caused by avian flu?
In the USA, a producer has been able to apply for government support for milk production losses due to avian influenza since the beginning of July 2024.
How does Canada, a neighbouring country of the USA, deal with avian influenza in cattle?
In Canada, a survey on milk sold to consumers has been carried out in May 2024. The milk was tested for the presence of the virus or parts of the virus using PCR. No positive results were found.
Canada requires dairy cows imported into Canada from the USA to test negative before importation.
Why is the approach to avian influenza infection in cattle different from that of poultry?
The legal approach to avian influenza infections in cattle is already different from the approach to infections in poultry. In cattle, avian influenza causes mild disease and does not increase mortality, unlike in productive poultry, which have a high mortality rate from the disease. The impact of infection in poultry is significantly higher than in cattle. Therefore, in poultry, avian influenza affects the export of live animals and animal products. For cattle or their products, the disease does not have a similar impact on exports. Until avian influenza was detected in cattle in the USA, transmission of the disease to cattle was considered unlikely. It is possible that bovine infections may also change the legislation on avian influenza in cattle in the future.
Does avian influenza in cattle affect international trade in cattle and their products?
According to the recommendations of the World Organisation for Animal Health (WOAH), there is currently no need to restrict international trade in healthy cattle or their products. For example, countries may choose to require imported animals to have a negative avian influenza test result before importation.