Most food related infections declined but a few stayed the same or went up, according to the recently released annual report on foodborne diseases in New Zealand covering 2020.

New Zealand Food Safety, part of the Ministry for Primary Industries (MPI), said public health and social actions introduced to prevent the spread of COVID-19 affected exposure behaviors and pathways, as well as changes in access to medical care and laboratory testing priorities.

In 2020, reporting rates for most foodborne diseases were lower, except for Listeria and Yersinia, compared to the previous three years. The coronavirus pandemic and related measures had a strong impact on rates of infections, according to the report.

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.

Campylobacter and Salmonella figures
In 2020, there were 5,289 cases of campylobacteriosis, 718 hospital admissions and no deaths reported with almost 4,000 cases estimated to be foodborne. There were 6,202 cases in 2019.

Monthly notifications ranged from 94 in April 2020 to 859 in December 2020. The highest notification rates were reported for children aged less than 1 to 4 years old.

In 2020, New Zealand Food Safety set a goal to reduce domestically acquired foodborne campylobacteriosis by 20 percent to 70.2 cases per 100,000 population by the end of 2024.

There were 20 outbreaks affecting 157 people with six outbreaks recorded as food as a possible mode of transmission. Raw milk was the suspected source for two of those.

In 2020, 708 cases of salmonellosis were recorded with more than 400 estimated to be foodborne compared to almost 1,200 cases in 2019. Data from the Ministry of Health shows 165 hospital admissions in 2020 for Salmonella infections.

Monthly notifications ranged from 22 in April to 92 in January and February. Notification rates were highest for children aged less than 1 to 4 years old.

Isolates from 635 cases were typed by the Institute of Environmental Science and Research’s (ESR) Enteric Reference Laboratory. Salmonella Typhimurium and Salmonella Enteritidis were the top types. Other common serotypes were Bovismorbificans, Brandenburg and Saintpaul.

There were eight outbreaks and two could have been caused by food with 12 people affected. Both were Salmonella typhimurium with one linked to retail raw fish and raw mussels and the other to roast pork and chicken.

E. coli, Listeria and Yersinia data
A total of 844 Shiga toxin-producing E. coli (STEC) infections were recorded with 330 judged to be food related. Data from the Ministry of Health showed 39 hospital E. coli admissions. There were 1,101 documented STEC infections in 2019.

Much lower rates in April and May 2020 were related to the impact of the COVID-19 public health response, according to the report. Monthly notifications ranged from 30 in April to 106 in March. The infection notification rate was highest for the less than 1 to 4 years old age group.

Of 556 typed patient isolates, 165 were identified as E. coli O157:H7. More than 100 were O26:H11 and 61 were O128:H2.

In 2020, there were 21 STEC patients logged in EpiSurv who developed hemolytic uremic syndrome (HUS), which is often fatal. Associated serotypes were mostly O157:H7 but also O26:H11, O38:H25 and O88:H8 or not reported. Another 35 HUS hospital admissions were recorded in 2020. Children younger than the age of 5 were mainly affected.

Of eight outbreaks, four with 14 patients were linked to food. One was linked to a chicken bun while the source of the other three food-related outbreaks was unknown. Patients in an outbreak at a long-term care facility were also infected with Campylobacter.

A total of 34 cases of Listeria infections with one death were reported compared to 31 cases in 2019. All patients in 2020 were hospitalized. Rates were highest in the 70 years and older age group. The Ministry of Health database showed 38 hospital admissions.

Yersinia cases went up from 1,186 in 2019 to 1,261 listed in EpiSurv in 2020 and 937 were estimated to be foodborne. The Ministry of Health database recorded 164 hospital admissions. Monthly notifications ranged from 23 in April to 163 in October. The highest notification rates were in the less than 1 to 4 years old age group. One outbreak affected two people but the source was not found.

Botulism, Shigella and viruses
One botulism outbreak from improperly home-preserved seafood hospitalized four people. In July 2021, MPI analyzed 100 samples of shellfish and sediments from the area where the shellfish eaten by the patients were harvested. This confirmed the presence of Clostridium botulinum type A in the environment.

There were five shigellosis outbreaks and one listed food as a possible source with two people sick. The outbreak was associated with overseas travel and no source was recorded.

There were 170 norovirus outbreaks with 10 reporting food or a food handler as a possible mode of transmission. In eight outbreaks, an infected food handler was the suspected source. One outbreak at a catered conference that sickened 77 people was linked to potato salad, which was tested and contained E. coli, however, patient stool samples were positive for norovirus and negative for E. coli.

Three sapovirus outbreaks were recorded. One had food as a possible mode of transmission with three associated cases. The suspected source was takeaway food eaten at home.

Seafood and toxins
One outbreak of ciguatera poisoning was reported with one probable and three confirmed cases. Consumption of fish imported from Fiji was the suspected cause.

One histamine (scombroid) fish poisoning outbreak involved 91 people. All patients had consumed Trevally fillets acquired from home delivery food supplier, HelloFresh, in the same week.

Eight Vibrio parahaemolyticus patients were reported in EpiSurv. Five hospital admissions were noted. An outbreak linked to raw mussels involved 16 people in June, seven of whom were hospitalized.

One case of Bacillus cereus intoxication was recorded in EpiSurv in October. Testing by ESR of curry with rice eaten by the person detected Bacillus cereus. One outbreak involved two people in July. The suspected vehicle was a takeaway rice meal.

There was one Clostridium perfringens outbreak with 14 cases but the source was not identified.

An outbreak of Staphylococcus aureus was associated with foodborne transmission. There were four lab confirmed and 16 probable cases linked to a hotel but the food vehicle was not found. Patients were also suspected to be infected with norovirus.

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