Listeria and Campylobacter both increased this past year in Ireland, according to figures from the Health Protection Surveillance Centre.

The number of listeriosis patients was the highest since the disease became notifiable in 2004. More than 3,000 Campylobacter infections were recorded. During 2018, 3,030 cases of campylobacteriosis were reported, an increase of 8.7 percent compared with 2,786 patients in 2017. “Campy” remains the most common cause of bacterial gastroenteritis in Ireland. It is the eighth consecutive year for which levels were up compared with rates between 2004 and 2010.

Campylobacteriosis occurs in all age ranges, with the highest rate in the 0 to 4-year-old group. This rate in younger children is a well described characteristic of the disease and seen at European level, according to the Health Protection Surveillance Centre (HPSC).

Three foodborne outbreaks but no source identified
Risk factors for campylobacteriosis include handling raw poultry or eating raw or undercooked poultry meat, as well as drinking contaminated untreated water or unpasteurized milk and products made with it.

There were five outbreaks of campylobacteriosis during the time frame reviewed. Three were reported as foodborne, but no sources were identified. Two were in long-term care facilities; 11 people were reported ill between them, three of whom were laboratory /confirm/ied. An outbreak of two lab confirmed cases linked to a hotel were also believed to have been from a food source.

“Notification of outbreaks of Campylobacter are less common than for other bacterial gastrointestinal pathogens; increasingly this is being regarded as a reflection of our inability to detect them as traditionally typing of Campylobacter strains has been of limited value,” according to HPSC.

During 2018, reports peaked between May and August. Country of infection was known for 56 people, of which twelve were foreign-travel related.

All patients reported in Ireland during 2018 were laboratory /confirm/ied, but data on species isolates was reported for only 13 percent of them. Of the 407 isolates, 92 percent were Campylobacter jejuni and 7 percent were Campylobacter coli, with only three being other species.

Antimicrobial resistance data were available on 46 isolates. Fifteen showed resistance to ciprofloxacin, 18 to tetracycline, with none having resistance to erythromycin.

Symptoms generally last a few days although sometimes recovery can take up to 10 days. Arthritis may develop following infection and in rare instances, a neurological condition known as Guillain-Barré Syndrome (GBS) may develop. GBS can last weeks or months. Most people make a full recovery, but some develop more chronic weakness and it can lead to death. It is estimated that one in every 1,000 reported campylobacteriosis cases leads to GBS.

Listeria: Two miscarriages and one death

In 2018, there were 22 cases of listeriosis reported, an increase of eight compared to 2017. No source was confirmed for any of them.

Ten occurred in the three months from July to September. All implicated people were in the recognized groups at risk for listeriosis, being elderly, having an underlying illness, being pregnant, or being neonatal.

One neonatal infant and four pregnancy-related patients were reported as having resulted in one stillbirth and two miscarriages.

Seventeen were non-pregnancy related, a 70 percent increase compared with 10 in 2017. Nine of these were male. Patients ranged in age from 42 to 92 years and three-quarters were 65 years of age and older.

Fourteen, including all four under 65 years old, had underlying disease which may have increased risk of listeriosis. Eight had bloodstream infections, two had meningitis and bloodstream infection, and five had other symptoms. One death was reported in 2018.

Isolates from 18 of the 22 notified cases were referred by the primary laboratories for typing; serotype 4b was the most common with 11 followed by serotype 1/2a with six.

The 18 isolates were distinguished into 10 different sequence types by whole genome sequencing, and comparison of sequence data ruled out the likelihood of links between them. As a few isolates were not available it was possible a small outbreak could have gone undetected.

“As no outbreaks were identified among the reported cases, it appears that there was a rise in the number of sporadic infections, and this was particularly noticeable among the elderly. This increase occurred primarily during the summer months of 2018, a period in which the weather was atypically hot,” according to HPSC.

Foods often associated with infection are ready-to-eat refrigerated and processed items such as pre-prepared cooked and chilled meals, soft cheeses, cold cuts of meat, pâtés and smoked fish.