The number of searches for vinterkräksjukan (norovirus) has increased rapidly on the agency's 1177 website, suggesting that the illness has begun to hit Swedes in large numbers.
“We set a threshold and last week there were so many people searching for the word that we can now assume the season has begun,” Public Health Agency epidemiologist Elsie Ydring said.
Another way of recording the start of the norovirus season is through analysis of voluntary reports to microbiological laboratories across the country.
Ydring said that the presence of the bug in these samples followed “the same pattern” as the online searches, suggesting a sharp increase in the vinterkräksjuka. However, she added that this does not give a totally accurate picture since it is not mandatory to report the illness.
“Most people do not go to the doctor [with vinterkräksjuka]; they stay at home until they get well,” she said. “What we're seeing is the tip of the iceberg.”
The virus is infamous in Sweden, with symptoms typically coming on very quickly following infection and including nausea, vomiting, diarrhoea and fever.
The health agency recommends good hand hygiene as the best defence against the illness, particularly using soap and water. Hand disinfectant alone is not sufficient but can be used as an extra precaution.
Most cases of vinterkräksjuka usually occur between November and April, reaching a peak in February (sometimes called vabruari in Sweden, because of the high numbers of parents who take time off to look after sick children, called vabba in Sweden).
Now that the Public Health Agency has declared the season has begun, it will provide weekly reports relating to its spread.
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