Wednesday February 5 2014
There is no evidence the new strain can pass between humans
“Experts are concerned about the spread of a new strain of bird flu that has already killed one woman in China,” BBC News reports.
The new strain, which has evolved from an existing bird flu virus called H10N8, has infected two people in China.
A case report in The Lancet medical journal warns that potential for a new pandemic “should not be underestimated”.
Their genetic tests of the strain suggests it has adapted to infect humans more easily.
That said, experts suggest there is currently no cause for alarm. There is no evidence that the new strain can pass between humans. Also, the woman who died of the new strain had pre-existing health conditions, including heart disease and high blood pressure, which may have made her more vulnerable to the effects of infection.
And for people living in the UK, the risk of contracting bird flu is extremely low. The UK became officially free of bird flu in 2008.
It is likely that the Chinese authorities will closely monitor the situation to assess whether there is a potential for a new pandemic to emerge.
What is bird flu?
Bird flu, or avian flu, is an infectious viral illness that spreads among birds. In rare cases it can affect humans. It is usually spread to humans by close and prolonged contact with infected birds.
Symptoms are the same as seasonal flu but there is a risk that an infected individual can develop complications, such as pneumonia, which can be fatal.
There are many types of bird flu, most of which are harmless to humans. However, two types have caused serious concern in recent years. These are the H5N1 (since 1997) and H7N9 (since 2013) viruses.
Although these viruses don't infect people easily and are usually not transmitted from human to human, hundreds of people have been infected around the world, leading to a number of deaths.
The H10N8 virus discussed in the current news has never been reported in a human before.
Why is bird flu in the news again?
Bird flu is in the news again because scientists have identified a new strain of the H10N8 virus. Their article, published in the peer reviewed medical journal The Lancet, reports on a 73 year old woman from Nanchang City in China, who was admitted to hospital in November last year with fever and severe pneumonia.
The woman had been exposed to chickens in a live poultry market a few days previously. Despite antibiotic and antiviral treatment she deteriorated rapidly, developed multiple organ failure and died nine days after the onset of symptoms.
The researchers took swab samples from the patient’s windpipe seven and nine days after onset of her illness. Laboratory tests showed they were positive for a new strain of the H10N8 virus, which they have called JX346.
What else did they find out?
The researchers carried out further detailed genetic analysis of the samples. They found that all the genes of the JX346 virus were of avian origin and that six genes share a common history with the avian H9N2 viruses, also found in poultry in China.
They suggest that JX346 might originate from “multiple reassortments” between different avian flu viruses. In other words, various strains are interacting with each other with the net result of a new strain being produced.
They also found the new strain had a gene mutation that is thought to be associated with increased virulence, meaning the virus might more easily infect people and the disease could be more severe.
The source of the patient’s infection is unknown. She had visited a live poultry market a few days before the onset of illness, however no H19N8 virus was found in samples collected from the poultry site since the patient’s visit.
What are the implications?
Any reports of bird flu viruses being found in humans is a cause for concern since at present, there are no vaccines against them and the human population has no pre-existing immunity to them. For example, by July 2013, the H5N1 virus had infected 633 people, 377 of whom had died, with Indonesia, Egypt and Vietnam experiencing most cases and fatalities. Since March 2013, there have been reports of people being infected with the H7N9 virus in eastern China. By July 2013, there were 134 confirmed cases and 43 deaths.
However, people who have had bird flu generally developed the virus after coming into close and prolonged contact with infected birds. Millions of birds have been killed during outbreaks to prevent the disease spreading and being passed on to people.
For both the above viruses, there have been some reports of limited human to human transmission, usually as a result of very close contact between family members.
It should be noted that the patient who died in China had several chronic illnesses and a weakened immune system which may have made her particularly susceptible to the virus. There is no evidence that the new strain had transmitted to close contacts of the patient.
For people in the UK the risk of catching bird flu is very low. There are a number of things you can do to reduce your risk when you visit areas where outbreaks have been reported, such as:
- avoid visiting live animal markets and poultry farms
- avoid contact with surfaces that are contaminated with bird droppings
- don't pick up or touch birds (dead or alive)
- don't eat or handle undercooked or raw poultry, egg or duck dishes
- don't bring any live poultry products back to the UK, including feathers
- always practice good personal hygiene, such as washing your hands regularly
There are no restrictions on travel to countries that have been or are currently affected by bird flu.
Analysis by Bazian. Edited by NHS Choices.
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