ITALY – Researchers in the journal Emerging Infectious Diseases have linked the death of five people in Italy to the consumption of unpasteurized cheese produced from contaminated cow’s milk.
According to the researchers, the incident is considered to be the largest and most severe outbreak associated with raw milk cheese in Italy.
In central Italy, there were 37 cases of Streptococcus zooepidemicus between November 2021 and May 2022, 23 of which required hospitalization.
Infections were found in 18 hospitalized Pescara-province residents from November 2021 to February 2022.
Septicemia, pharyngitis, arthritis, uveitis, and endocarditis were among the symptoms seen. The five people died from severe meningitis.
The affected population ranged in age from 6 to 98, with a median age of 79. There were 21 females and 16 males that were ill.
19 hospitalized patients were sent to Teramo, Italy’s Istituto Zooprofilattico Sperimentale, where the researchers collected 21 isolates.
All 21 clinical strains shared a family tree, suggesting that the patients’ infections originated from the same place.
The local government established a task team including medical professionals, ecologist, scientists, microbiologists, and communication specialists to assess the outbreak.
Studies and whole genome sequencing (WGS) revealed that the outbreak’s source was unpasteurized fresh dairy products.
31 patients were found to have consumed soft or semi-soft cheeses from regional producers or vendors, according to an epidemiological analysis.
Streptococcus zooepidemicus was detected in an unpasteurized bulk cow milk sample taken from one dairy producer within the outbreak area, reports Food Safety News.
Afterwards, 18 Streptococcus zooepidemicus strains were discovered during an official inspection of two bulk milk tanks and two samples of cured raw milk cheese.
These strains clustered with the clinical ones, according to further analysis, demonstrating a close relationship between patient samples and them.
A review of data from the Istituto Zooprofilattico Sperimentale found a strain that was isolated from the milk of a cow with mastitis in November 2021. The animal belonged to the same operator whose products tested positive.
It also formed a cluster with the other strains isolated from patients and raw milk products after being sequenced.
Construction work in the barn from October to November 2021, according to the farmer with the positive cow, may have stressed the animal and made it more susceptible to mastitis.
In February 2022, local authorities put in place measures to control and stop the spread of Streptococcus zooepidemicus.
The government ordered the pasteurization of the milk used to make cheese, and all dairy products were pulled from shelves and dealers in the area. Ripening cheeses were also destroyed.