Campylobacter is continuing to decline but E. coli is still going up, based on figures from the 2019 report on foodborne disease in New Zealand.

New Zealand Food Safety is part of the Ministry for Primary Industries (MPI) and EpiSurv is the country’s notifiable disease surveillance system.

In 2019, a continued increase was seen for Shiga toxin-producing E. coli (STEC) infection with the number of cases passing 1,000 for the first time. At least part of this rise is thought to be because of testing changes.

Yersiniosis, salmonellosis and shigellosis notification rates were similar to the previous year but Campylobacteriosis and cryptosporidiosis have decreased compared to the past two years.

Campylobacter decline
During 2019, 6,202 cases of campylobacteriosis and no deaths were reported in Episurv with 3,394 estimated to be foodborne. More than 700 hospital admissions were recorded.

Campylobacteriosis cases and rates per 100,000 population in 2019 were the lowest since 1992. In 2020, New Zealand Food Safety introduced a goal of reducing foodborne campylobacteriosis in the country by 20 percent by the end of 2025.

The monthly number of notifications ranged from 306 in April to 951 in January. The highest age-specific notification rates were reported for children aged 1 to 4 years at 597 cases and infants aged less than 1 year at 128 cases. The highest hospitalization rates were for the 70 years and over age group and infants aged less than 1 year. For cases wher information was provided, 14 percent had travelled overseas during the incubation period.

There were 20 outbreak notifications in EpiSurv and eight had food as a possible mode of transmission affecting 81 people. Three were linked to raw milk, one to chicken liver pâté and another to reheated rice. An outbreak in a prison left three people needing hospital treatment.

Salmonella steady
During 2019, 1,188 cases of salmonellosis and no deaths were reported in EpiSurv with 484 believed to be foodborne. In total, 230 hospital admissions were recorded in the National Minimum Dataset (NMDS) system. EpiSurv and the Ministry of Health’s NMDS database are separate and hospital admission can occur without cases being notified in the former system.

The monthly number of notifications ranged from 62 in June to 196 in January. Notification and hospitalization rates were highest for infants aged less than 1 year and the 1 to 4 age group. For patients wher information was provided, 34 percent had travelled overseas during the incubation period.

There were 27 salmonellosis outbreak notifications in EpiSurv and 15 had food as a possible mode of transmission. They affected 186 people and 26 were hospitalized. Salmonella Infantis in flavored water caused four confirmed and 30 probable infections. Salmonella Typhimurium in alfalfa sprouts was behind 68 confirmed and two probable cases. Salmonella Enteritidis was linked to four outbreaks, one of which was associated with travel to Tonga.

A total of 1,055 isolates from cases with Salmonella were typed by the ESR Enteric Reference Laboratory. Serotypes most commonly reported besides Salmonella Typhimurium and Enteritidis were Bovismorbificans, Salmonella 4,5,12:i:−, Brandenburg and Stanley.

E. coli on the rise
A total of 1,101 cases of Shiga toxin-producing E. coli infection and one death were reported in EpiSurv with 331 estimated to be foodborne.

The number of notifications ranged from 59 in December to 162 in March. The infection rate was highest for the less than 1 year age group with 51 cases and the 1 to 4 years age group with 188 cases. The number of hospitalizations was highest in the 70+ age group (13 admissions). For patients wher information was provided, 12 percent had travelled overseas during the incubation period.

only one of 15 outbreaks with three infections was judged to have been foodborne. The suspected vehicle was raw milk from a farm. Patients were also infected with Campylobacter.

Isolates from 781 patients infected with STEC were reported by the ESR Enteric Reference Lab in 2019. Of 791 associated isolates, 203 were identified as E. coli O157:H7, 484 as non-O157 and for 104 isolates the serotype could not be determined. Of the non-O157 isolates identified, 119 were typed as O26:H11, 55 as O128:H2 and 27 as O38:H26.

In 2019, 21 STEC cases notified in EpiSurv developed hemolytic uremic syndrome (HUS). Associated serotypes were O157 11 times, O26:H11 on three occasions and O38:H25 and O88:H8 once each.

Fifteen HUS cases were reported to the New Zealand Pediatric Surveillance Unit. One death was recorded with E. coli O26 isolated. Risk factors for seven patients included drinking unpasteurized milk, living on a farm/lifestyle block, drinking tank water and swimming in a public pool.

Listeria, norovirus and Clostridium perfringens
During 2019, 31 cases of listeriosis were reported in EpiSurv and all were hospitalized. There were no outbreaks. A total of 46 hospital admissions were recorded in the NMDS system.

Rates were highest in the 70 years and over age group for both the notifications (13 cases) and hospitalizations (16 cases). One perinatal patient died. Another person notified with listeriosis died, but it was not associated with the infection.

Nine of 181 norovirus outbreak patients reported had food or a food handler as one of the possible modes of transmission with the latter named four times. They affected 119 people. Flavored water was suspected in one outbreak while another may have been caused by ham sandwiches or chicken burgers.

All three Clostridium perfringens outbreaks, with 53 cases and no hospitalizations, reported food as a possible mode of transmission. Suspected sources included a beef sirloin meal with condiments, pork belly and leafy vegetables. The source for the other outbreaks were thought to be roast lamb and chicken burrito.

There were 24 giardiasis outbreak reports and two had food as possible transmission. One outbreak linked to garden salad caused one confirmed and 17 probable infections. For a household-based outbreak with four cases, no food vehicle was identified.

Poisoning from fishery products
Four of nine shigellosis outbreaks had food as a possible mode of transmission. Nine people fell sick and four were hospitalized. Three outbreaks were linked to overseas travel to India, Samoa and Tonga.

Two of four yersiniosis outbreaks were linked to food. They affected 65 people with five needing hospital treatment. Yersinia pseudotuberculosis caused a small outbreak with the source unknown. Another affected 62 confirmed and probable cases in a prison that may have been caused by chicken meals. Campylobacter was also isolated from patient samples.

Ten cases of ciguatera fish poisoning were reported in EpiSurv and 14 hospital admissions recorded in the NMDS database. One outbreak had four probable cases exposed at home. Consumption of imported fish was the suspected cause.

Ten cases of histamine (scombroid) fish poisoning were reported and nine hospital admissions recorded in the NMDS database. Three outbreaks involved nine people linked to seafood chowder and gurnard fish.

Two cases of toxic shellfish poisoning and no deaths were reported in EpiSurv. The toxin type was not specified. One person had eaten cooked squid from a food outlet. The other consumed raw and cooked recreationally collected tuatua. Seven cases had ‘other fish and shellfish poisoning’ in the NMDS database.

One outbreak of Vibrio parahaemolyticus infection potentially caused by food involved 24 people, of which two were hospitalized. It was linked to mussels and was the first such outbreak since 2009.