Sweden is experiencing a sharp seasonal increase in campylobacter infections, with reported cases rising from around 30 per week in early June to over 200 last week, according to the Public Health Agency of Sweden (Folkhälsomyndigheten).
The bacterium campylobacter is a common cause of bacterial gastroenteritis and typically spreads through the consumption of contaminated poultry. It causes symptoms such as diarrhoea, fever, nausea and, occasionally, chills. While most cases resolve without medical treatment, more severe symptoms can occur in rare cases.
“The number of notifications begins to increase significantly from July,” said Rikard Dryselius, investigator at the Public Health Agency. “It usually peaks in August and then decreases again towards autumn.”
Seasonal patterns and environmental factors
The summer spike in campylobacter cases is described as highly seasonal. According to health authorities, warmer weather contributes to a higher bacterial load in nature and food systems.
“There is more activity in nature during summer than winter, and that’s why campylobacter is significantly more common during warm periods,” Dryselius explained.
The current rise fits historical patterns, but the steep increase in reported infections has led health authorities to renew recommendations on food hygiene, particularly in relation to the handling and cooking of chicken, which remains the most common source of infection.
Public health guidance and food safety
The Public Health Agency continues to stress preventive measures such as thorough cooking of poultry, avoiding cross-contamination in kitchens, and maintaining strict hand hygiene after handling raw meat or being in contact with animals.
While the majority of cases are mild, the agency encourages anyone experiencing severe or persistent symptoms to seek medical attention. Monitoring will continue through August, with updated data expected weekly.
