New Zealand has reported foodborne infection and outbreak figures for 2021 with statistics still affected by a coronavirus.

In 2021, the COVID-19 pandemic and public health measures taken to control the spread of the disease continued to impact notification rates of foodborne disease. The number of Campylobacter, Salmonella, E. coli, and Yersinia infections went up from 2020 while Cryptosporidium, Hepatitis A, and Listeria cases fell.

EpiSurv and the Ministry of Health’s database on hospitalizations are separate and hospital admission can occur without cases being listed in EpiSurv, the notifiable disease surveillance system.

Campylobacteriosis rates returned to a level higher than in 2020 but were lower than the 2017 to 2019 average. For the first time in more than 15 years, there were no outbreaks due to raw milk.

Campylobacter and Salmonella data
A total of 5,729 Campylobacter cases were reported with 4,292 estimated to be foodborne and 846 hospitalizations.

The highest age-specific notification rate for campylobacteriosis was in children aged 0 to 4. The largest hospitalization rate was for the 70 and over age group.

There were 12 outbreak notifications in EpiSurv with 32 sick and five having food as a possible mode of transmission. New Zealand Food Safety investigated three further outbreaks. Two reported chicken pâté as a suspected source and one was linked to lambs’ fry.

Overall, 714 Salmonella infections were recorded with 443 estimated to be foodborne and 217 hospitalizations. Reporting and hospital admission rates were highest for children in the 0 to 4-year-old group.

Isolates from 660 cases revealed Salmonella Typhimurium and Enteritidis were the top serotypes. Others commonly reported were Salmonella Bovismorbificans, Brandenburg, and Saintpaul.

Five outbreaks included 90 cases and 18 people had to be hospitalized. One Salmonella Enteritidis outbreak with 46 cases was linked to poultry while another with 28 patients was traced to alfalfa and radish sprouts. There were two small Salmonella Typhimurium outbreaks and one Salmonella Weltevreden epidemic by undercooked chicken.

E. coli and Listeria

A total of 913 Shiga toxin-producing E. coli (STEC) infections were reported with 364 estimated to be foodborne and 43 hospitalizations.

Of 626 typed isolates, 182 were E. coli O157:H7 and 443 were non-O157. As in the previous three years, the most frequently typed non-O157 serotypes were E. coli O26:H11 and E. coli O128:H2.

STEC infection notification and hospital admission rates were highest for the 0 to 4-year-old age group followed by those older than 70. There was one outbreak with two cases.

In EpiSurv, 16 cases were reported to have developed Hemolytic Uremic Syndrome (HUS). The associated serotypes were O157:H7 and O26:H11. There were also 40 hospital admissions recorded in 2021. The highest rates of hospitalized cases due to HUS were for children 0 to 4 years old.

In 2021, 32 cases of listeriosis were reported in EpiSurv, with four deaths and 31 hospitalizations. Of 38 hospital admissions, 19 had listeriosis as the principal diagnosis. Notification and hospitalization rates were highest for people above the age of 70.

One outbreak included four patients and one death. An investigation identified cooked ready-to-eat meats bought from a supermarket as a possible source. Whole genome sequencing of unopened product samples and the processing environment from a producer showed a close association with case isolates. Contamination originated at Pestell’s Rai Bacon Company.

Other agents and outbreaks
One case of ciguatera poisoning was reported in EpiSurv. This person had consumed tropical fish. There were also two hospital admissions in the Ministry of Health’s database. Three cases of toxic shellfish poisoning were reported in EpiSurv and there were four hospital admissions.

Six cases of histamine (scombroid) fish poisoning were recorded in EpiSurv and there were 10 hospital admissions. One outbreak linked to soup with fermented tuna and mackerel sickened two people.

Two Vibrio parahaemolyticus outbreaks involved 28 cases and eight hospitalizations. One was linked to raw mussels and the other to raw oysters. Another three suspected outbreaks were investigated by New Zealand Food Safety.

A total of 27 outbreak-related Clostridium perfringens cases were recorded. A dozen cases who provided information had eaten a corned beef meal. A review of kitchen processes found the meat stock solution saved from cooking the corned beef and used to make gravy two days later was unlikely to have been cooled sufficiently quickly.

There were eight cryptosporidiosis outbreaks with 44 cases and two hospitalizations. Two had raw milk as the possible mode of transmission. In both outbreaks, multiple households consumed milk from the same supplier over the same period. The subtype identified in both outbreaks was a type of Cryptosporidium parvum commonly associated with cattle.

Six norovirus outbreaks with 171 cases and two hospitalizations reported food or a food handler as a possible mode of transmission. These involved raw oysters, chicken breast, and BBQ food.

Four Yersinia outbreaks affected 29 people. One was linked to raw milk or untreated drinking water and another to bacon eaten after the use-by date.

New Zealand Food Safety investigated five possible cases of Bacillus cereus intoxication associated with a food service operator. Temperature control issues were identified as a contributing factor.