A long-lasting outbreak of Salmonella Typhimurium U323 associated with several pork products, Denmark, 2010.

This paper shows that control of foodborne disease outbreaks may be challenging even after establishing the source of infection. An outbreak of Salmonella Typhimurium U323 infections occurred in Denmark from March to September 2010, involving 172 cases. Before the detection of human cases, several positive isolates of the outbreak strain had been found in a particular pig slaughterhouse and thus early traceback, investigation and control measures were possible. Several batches of pork and pork products were recalled and the slaughterhouse was closed twice for disinfection. No single common food item was identified as the outbreak source, but repeated isolation of the outbreak strain from the slaughterhouse environment and in pork and products as well as patient interviews strongly suggested different pork products as the source of infection. Furthermore, a matched case-control study identified a specific ready-to-eat spreadable pork sausage (teewurst) as the source of a sub-outbreak (matched odds ratio 17, 95% confidence interval 2·1-130).

Epidemiology of campylobacteriosis in Denmark 2000-2015.

Campylobacter is the most frequently occurring cause of bacterial gastroenteritis in Europe. Unlike other zoonotic diseases, European-wide incidences of Campylobacter infections have increased during the past decade, resulting in a significant disease burden. In Denmark, campylobacteriosis is notifiable by laboratory and a unique registration system of electronic transfer and storage of notified Campylobacter cases linked to the national person register of age, gender and geographical location allows collection of comprehensive case data. Using national surveillance data, we describe Campylobacter infections in Denmark from 2000 to 2015, focusing on age-specific incidences, geography, seasonality and outbreaks. During the observed period, a total of 60,725 Campylobacter infections were registered with a mean annual incidence of 69.3 cases/100,000 population. From 2000 to 2014, the incidence of campylobacteriosis decreased by 20%, followed by an apparent increase of 20% from 2014 to 2015. Approximately one-third of cases were travel-related. Incidences were highest in males, young adults aged 20-29 years and children under 5 years of age. Generally, children under 10 years of age living in rural areas were at higher risk of infection. Infection patterns were seasonal with an increase from May to October, peaking in August. Outbreaks were identified each year, including four large waterborne outbreaks which all occurred following heavy rainfall events. For the most part, patterns of Campylobacter infection in Denmark during 2000 to 2015 remained remarkably constant and followed what is known about the disease with respect to demographic, temporal and spatial characteristics. To establish better targeted prevention and control measures, the current knowledge gaps regarding both Campylobacter microbiology (degree of clonal diversity and clustering) and the importance of different risk factors (food versus environment/climate) need to be filled.

Whole-genome sequencing of Campylobacter jejuni isolated from Danish routine human stool samples reveals surprising degree of clustering.

OBJECTIVES: Outbreaks of Campylobacter are traditionally considered to be rare; however, rather than being the true nature of the disease, this may reflect our present inability to detect them. The aim of this study was to determine the genetic and epidemiological degree of clustering among Campylobacter jejuni isolates from Danish patients. METHODS: Whole-genome sequencing (WGS) was applied to 245 C. jejuni isolates from patients with domestically acquired infection over a 9-month period in 2015 and 2016. RESULTS: WGS demonstrated that 62 of the 245 isolates (25%) clustered genetically. In total, 21 genetic clusters were identified of which four (18%) consisted of five isolates or more. Seventeen (81%) of the 21 genetic clusters were clustered in space and/or time. Of the 245 isolates, 49 (20%) were part of a temporal and/or geographical cluster. The identified clusters included two outbreaks; one which had not been identified through the existing surveillance system. CONCLUSIONS: Using WGS, we show that Campylobacter case clustering and even outbreaks appear to occur more often than previously assumed, providing important new insight into the relatively poorly understood epidemiology of the most important cause of bacterial gastroenteritis in the industrialized world.

Detecting non-typhoid Salmonella in humans by ELISAs: a literature review.

Non-typhoid salmonellosis is one of the most common causes of foodborne illness throughout the world. Serological methods for the diagnosis of Salmonella infections vary widely and the most commonly used test is limited by high running costs as well as low sensitivity and specificity. Fast and reliable immunoassays which detect subunit antigens for Salmonella enterica subsp. enterica serovar Typhi are commercially available but at present there is no international consensus on similar tests for non-typhoid salmonellosis. In contrast to the veterinary and food sectors, most immunoassays for non-typhoid human Salmonella diagnosis are developed in-house and used in-house for research or surveillance purposes, rather than for routine diagnostics. Considering the current burden of disease, the development of a validated and standardized, commercially available antibody assay for diagnosing non-typhoid human salmonellosis could be of great benefit for diagnostic and surveillance purposes throughout the world.