Botulism due to traditional home-canned food still public health challenge

They found improper canning procedures are the primary reason for cases and outbreaks in the southern region.

Researchers said this suggests stronger efforts should be made to raise public awareness of the risk of foodborne botulism, especially with respect to home-preserved foods, as well as improving training of front-line medical personnel, to ensure a quick and accurate diagnosis.

Botulism is a disease caused by a toxin made by Clostridium botulinum and is a communicable disease in Europe.

Foodborne botulism in Italy​

In Italy, which has one of the highest incidence rates in Europe (0.03 cases per 100,000 population) it is monitored through a case-based passive surveillance system.

From 1986 to 2015, 466 confirmed cases of botulism were recorded (of 1,257 suspected).

Of these, 421 were foodborne (most frequently due to eating improperly home-canned foods).

The largest peak in notification of suspected cases was in 1996 as a consequence of four outbreaks due to food (mascarpone cheese and olives) and in 2013 due to a suspected outbreak linked to pesto sauce.

Type B toxin was implicated in 79.1% (261/330) of confirmed incidents followed by type A (32/330).

A problem tradition​

Most confirmed incidents, involving 241 people, originated in rural areas of central and southern regions in Campania (50/285), Puglia (40/285), Lazio (31/285), Sicilia (22/285) and Calabria (21/285).

“In these areas, many people still maintain the tradition of preparing home-canned foods, due to the low cost and wide availability of raw food materials,” ​said the researchers. ​

“In the 10 years to 2015, an increasing number of cases were reported in Emilia Romagna, Lombardia and Piemonte (northern Italy). More than 90% of these cases involved university students (mostly male) of southern Italian origin, who had consumed homemade canned food prepared by their mothers.”​

Although all patients were admitted to hospital, length of hospitalisation was unknown because the reporting system did not record this information.

A total of 16 deaths were recorded with four in elderly patients aged over 80 who lived alone.

Serum was tested for 275 out of 421 patients of confirmed foodborne cases and resulted positive only for 20.4%. Remaining cases were confirmed by direct detection of toxins in faecal samples (52 patients) or foods (159 patients).

Food was identified as the transmission vehicle by lab testing or epidemiological investigations in 41.4% (118/285) and 30.7% of confirmed incidents, respectively.

A total of 80.5% (95/118 incidents, involving 143 people) of food items linked to confirmed incidents consisted of homemade canned food, while the remaining 23 was commercial food.

Botulism rates in US​

Meanwhile, 199 confirmed and 14 probable cases of botulism were reported to the US Centers for Disease Control and Prevention (CDC) in 2015​.

This compared to 161 laboratory-confirmed and 16 probable cases in 2014.

Among confirmed cases in 2015 foodborne botulism accounted for 39 (20%) cases and six for probable cases.

The year before laboratory-confirmed foodborne botulism made up 15 cases and five probable cases.

The 39 cases were from seven states and there were five outbreaks accounting for 37 confirmed cases.

One was associated with home-canned potatoes in a potato salad served at a church potluck (27 cases), ​one with fermented seal flipper (four cases) and one with beets roasted in aluminum foil and kept at room temperature for several days then made into a soup (two cases).

Toxin type A accounted for 34 (87%) and toxin type E for five (13%). One death was reported.

Source: Eurosurveillance, Volume 22, Issue 24, 15 June 2017​

“Botulism in Italy, 1986 to 2015​”

Authors: F Anniballi, B Auricchio, A Fiore, D Lonati, CA Locatelli, F Lista, S Fillo, G Mandarino, D De Medici