Swine flu A(H1N2)v: UK detected its first human case

Symptoms of influenza A(H1N2)v, clade 1b.1.1, were mild in the individual, who has fully recovered, health authorities said in a news release. And hundreds of documented cases of swine flu occur globally every year, each transmitted from a pig to a human, and typically no further.

But authorities are unsure of how the UK patient became infected, leaving open the possibility that the virus is already spreading in the community. And mild symptoms in one patient isn’t a guarantee of mild symptoms in others, experts tell Fortune.

The HSA is working to assess the risk to humans, searching for other possible cases, and increasing surveillance in health facilities in parts of North Yorkshire, as part of an ongoing investigation.

“We are working rapidly to trace close contacts and reduce any potential spread,” Meer Chand, incident director at the HSA, said in a statement.

In the meantime, it recommends that those with respiratory symptoms like the following should avoid contact with others, particularly those who are elderly or have medical conditions:

• continuous cough
• high temperature, fever, or chills
• changes in senses of taste and/or smell
• shortness of breath
• unexplained fatigue
• muscle aches and pains not due to exercise
• lack of appetite
• headache longer lasting/more severe than usual
• sore throat
• stuffy or runny nose
• diarrhea

First human swine flu case of its exact kind

The infection marks the first time the exact type of H1N2 virus has been detected in humans, though an incredibly similar strain has been detected in pigs. There have been a total of 50 human cases of H1N2 reported globally since 2005. But none are genetically related to the clade just detected in the U.K.: 1b.1.1.

A single case of the new type of flu isn’t concerning to Rajiv Chowdhury, professor of global health at the Robert Stempel College of Public Health and Social Work at Florida International University in Miami.

What concerns him, however, is the possibility of cases going undetected outside of the the UK, which has far better best genomic surveillance capabilities than most other countries in the world.

While it’s reassuring that the individual experienced only a mild course of illness, it doesn’t rule out the possibility of a more severe course in other humans, if they’re infected, based on factors like age, other diseases they have, immunity status, and the amount of virus they were exposed to, he told Fortune.

Dr. Michael Osterholm—director of the University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP)—agreed with Chowdhury, telling Fortune that sporadic cases of swine flu are not unexpected. He pointed to the lack of report of human-to-human transmission so far as an encouraging sign.

Hundreds of cases of swine flu occur in the U.S. each year, usually linked to agricultural fairs, Dr. Amesh Adalja, an infectious disease specialist and senior scholar at the Johns Hopkins Center for Health Security, told Fortune.

“Most of these viruses do not have the capacity to spread between humans,” he said. “So it will be important to understand the transmission chain that led” to the human’s infection, including if that human had any exposure to pigs.

If not, the case could signal that wider community spread is occuring.

Humans are occasionally infected with the swine flu by pigs, usually after exposure to pigs or contaminated environments. Even more rarely, the virus transmits from an infected human to other infected humans, as was the case with the H1N1 pandemic of 2009.

This is a developing story and will be updated.