Infectious Diseases 2023

Campylobacteriosis: Campylobacteriosis is the most commonly notified potentially foodborne disease in New Zealand. The reduction of human cases of foodborne campylobacteriosis is a strategic priority for New Zealand Food Safety, with a performance target of a reduction in rates of foodborne campylobacteriosis by 20% from 88 to 70 per 100,000 population by the end of 2024. Between 2013 and 2019, the notification rate of campylobacteriosis was in the range of 124.6 to 153.9 notifications per 100,000 population. The trend for the previous three-year mean was generally downward over that period. In 2020, the campylobacteriosis notification rate (104.0 cases per 100,000 population) was much lower compared to the previous years, likely due to the impact of COVID-19. In 2022, the notification rate increased to 114.7 cases per 100,000 population. The highest age-specific notification rate for campylobacteriosis in 2022 was reported for children aged 1 to 4 years (230.1 per 100,000 population). The highest hospitalisation rate was for the 70 years and over age group (51.0 admissions per 100,000 population). The significantly higher number of cases and rate of campylobacteriosis in rural areas (215 per 100,000 population) compared with urban areas (85 per 100,000 population) in 2022 suggests that risk factors other than food, including direct contacts with farm animals and exposure to potentially contaminated water may be assuming greater importance as a source of infection.
Salmonellosis: During 2022, 750 individual cases (14.6 per 100,000 population) of salmonellosis and no resulting death were reported. It has been estimated by expert consultation that 62.1% (95th percentile credible interval: 35.2% to 86.4%) of salmonellosis incidence is due to foodborne transmission. It was further estimated that approximately 19% of foodborne salmonellosis was due to transmission via poultry. In 2022, notification and hospital admission rates of salmonellosis were highest for children in the <1 years age group (83.3 cases and 23.3 admissions per 100,000 population). In 2022, isolates from 654 notified cases with non-typhoidal Salmonella infections were typed. S. Typhimurium (325 cases) and S. Enteritidis (69 cases) were the most common serotypes identified.