A dangerous virus from a sick dog: in China three members of a family fell ill after caring for a golden retriever, and none of them had been bitten by a tick

What happened

Chinese scientists have described an unusual family cluster of severe fever with thrombocytopenia syndrome (SFTS) in the journal PLOS Neglected Tropical Diseases. Three people in one family in south-east China fell ill: a 57-year-old man, then his son two days later, and his wife a day after that. None of them had been bitten by a tick, even though that is how people usually become infected.

The one thing all three had in common was that they had been caring for a sick golden retriever. Two other family members who had no contact with the dog stayed healthy.

What SFTS is

Severe fever with thrombocytopenia syndrome is a viral disease first described in China around 2010. It is caused by a virus belonging to the bandaviruses. The disease brings high fever, weakness, vomiting, diarrhoea and a sharp fall in the number of platelets in the blood. In severe cases there is bleeding and damage to the kidneys and nervous system.

How dangerous it is

SFTS is a serious disease. Depending on the data, it is fatal in 10% to 30% of human cases, especially in older people. There is no specific treatment or vaccine; doctors support the organs. That is why it is important to suspect the disease early and seek help.

Why platelets fall

Platelets are blood cells responsible for clotting. The SFTS virus attacks cells of the immune system and the bone marrow, and the body starts destroying platelets on a large scale. When there are too few, the blood clots poorly, and bruising and bleeding from the gums and nose appear. It is this feature that gives the disease its name.

Where the disease occurs

SFTS occurs in China, Japan and South Korea and in some other countries of East and South-East Asia. Its main vector is the Asian longhorned tick, Haemaphysalis longicornis. Infections usually happen in spring and summer, when ticks are active. Neither this tick nor the virus has been found in Europe or the UK so far.

How the family became infected

The researchers pieced together what happened. First the dog fell ill and the family looked after it: feeding it, cleaning up after it, stroking it and wiping away discharge. Then three people fell ill one after another. As nobody had been bitten by a tick, the researchers concluded that the virus had passed from the dog through contact with its discharge, blood or saliva.

How this was confirmed

To test this, the researchers took samples from the dog and from a tick found on it and compared the genetic material of the virus. The virus genomes from the dog, the people and the tick matched by 99.94% to 100%. That is strong evidence that all the infections belong to one chain: the tick infected the dog, and the dog infected the people.

How long the dog was infectious

The most worrying finding concerns how long the virus was shed. It was found in nasal and urethral swabs from the dog for 23 days, in blood serum for 27 days and in rectal swabs for at least 30 days. So a sick dog could be a source of infection for more than a month.

Why it matters

Until now SFTS was thought to spread mainly through tick bites, and from person to person through close contact with a patient's blood. Infections from cats had already been described in Japan. The new study shows that dogs can infect people too, and over a long period. That matters for owners, vets and rescue centre staff.

What is known about cats

In Japan, cats become particularly ill with SFTS, and there are documented cases of people, including vets, catching it from sick cats. In cats the disease is often severe, with high mortality. Japanese vets therefore wear protective clothing and isolate sick animals whenever SFTS is suspected.

How dogs are affected

In dogs, SFTS can cause fever, lethargy, loss of appetite, vomiting and diarrhoea, as well as low platelets on blood tests. Some dogs cope with the infection better than cats, but as this case shows, they still shed the virus. Diagnosis is made by detecting the virus's genetic material.

How it is diagnosed

In people, SFTS is suspected when there is a high fever with low platelets and white blood cells, especially if the person has been outdoors or has cared for a sick animal. The diagnosis is confirmed by a blood test for the virus's genetic material. Doctors need to know about contact with animals: in this case, it was the mention of the sick dog that helped find the source.

What rescue centres should do

In rescue centres and vet practices in countries where SFTS occurs, animals with fever and low platelets should be isolated at once. Staff should wear gloves, gowns and masks, and goggles if there is a risk of splashes. Discharge from sick animals should be cleaned up with disinfectant. This lowers the risk of infection for people and other animals.

Limitations of the study

The authors stress that this is an observational study of a single family cluster. It does not show how often dogs pass the virus to people, only that it is possible. Larger studies are needed to estimate the risk. Even so, the researchers believe SFTS should also be seen as a disease that can be caught from pets.

How people protect themselves in Asia

In countries where SFTS occurs, owners are advised to treat dogs and cats against ticks regularly, check them after walks and not handle sick animals without gloves. If a pet falls ill with fever and low platelets, the owner should tell the vet straight away and see a doctor if they feel unwell themselves.

What owners of sick dogs should know

A sick dog should be looked after carefully. Wear gloves when clearing up vomit, faeces and urine, wash your hands with soap and do not let the dog lick your face, especially your eyes and mouth. This advice applies not only to SFTS but to many infections that pass from animals to people.

Is the virus a risk for Europe

SFTS does not currently occur in Europe because its main vector is absent. But scientists are watching the spread of Asian ticks closely: Haemaphysalis longicornis has already spread to North America and Australia. Animals are also sometimes brought in from Asia, and vets should keep such a disease in mind.

Similar diseases in Europe

Europe has its own dangerous tick-borne diseases. Crimean-Congo haemorrhagic fever occurs in Spain, the Balkans and Turkey and is spread by Hyalomma ticks. Tick-borne encephalitis is widespread in central and northern Europe and has now been detected in ticks in parts of England. In dogs, ticks transmit babesiosis, ehrlichiosis and anaplasmosis. So tick protection matters here too.

If you are bringing a dog from Asia

If you are bringing a dog or cat from China, Japan or Korea, check it for ticks and treat it before travelling. After arrival, take it to a vet and say where it came from. If the animal has a fever, is lethargic or is bleeding, the vet needs to know about the journey in order to consider rare diseases.

How to protect your dog from ticks

1. Use tick treatments all year round or throughout the tick season.
2. Check your dog after every walk in woods and meadows.
3. Remove ticks with tweezers or a tick hook, not with bare fingers.
4. Wear gloves when caring for a sick animal.
5. Wash your hands after contact with your dog's discharge.

What it means for vets

For vets, the case from China is a reminder that some infections pass from animals to people not only via vectors but also through direct contact. Gloves, masks and hand-washing when handling sick animals with a fever are simple measures that protect both vets and owners.

Why the One Health approach matters

Scientists see this case as an example of how closely the health of people, animals and the environment are linked. Ticks live in the wild, dogs bring them home, and people catch infections from dogs. Preventing such outbreaks requires doctors, vets and tick specialists to work together.

What this means for Europe

There is no direct SFTS risk for people in Europe at present, but the case from China shows that a dog can pass a dangerous virus to family members over a long period. Tick protection, gloves when caring for a sick pet and hand-washing also protect against European infections such as babesiosis, anaplasmosis and tick-borne encephalitis.

When to see a vet

Take your dog or cat to the vet if it has a fever, is lethargic, stops eating, is vomiting, has diarrhoea or is bleeding from the nose or gums, especially after a tick bite or a trip to Asia. If you feel unwell after caring for a sick animal, see a doctor and mention your pet.