Studies shine light on Irish E. coli infections, parasites in Peru

Researchers have looked at patterns in sporadic Shiga toxin–producing E. coli (STEC) infections in Ireland.

The Republic of Ireland often reports the highest annual incidence rates of STEC in the European Union. There is a high proportion of sporadic STEC infections and they are often associated with environmental exposures.

Researchers investigated space and time patterns of STEC in Ireland using statistical tools. Understanding spatial and temporal patterns of infection informs targeted surveillance and control interventions. Findings were published in the journal Emerging Infectious Diseases.

Of 2,783 confirmed sporadic cases during 2013 to 2017, scientists geolinked 2,755 to a distinct spatial area. Sporadic cases were more frequent in rural areas than urban sites.

They identified three distinct regions as having particularly high space-time cluster recurrence rates. These were southwest and east of Limerick city, and northeast of Galway city, indicating presence of persistent STEC reservoirs in these areas that cause regular exposure and transmission.

The most frequently confirmed serogroups associated with infection were E. coli O26 and E. coli O157. Of the remaining serogroups, STEC O145, O103, and O146 were the only ones associated with more than 50 confirmed infections.

E. coli by period and age group
Researchers observed a yearly increase in case numbers with 463 in 2013 and 674 in 2017. STEC O157 infection modestly increased during the study period, with a marked decrease in 2015. Incidence of STEC O26 increased from January 2013 to April 2016, then decreased. Other serogroups had a gradual rise during the study period.

Temporal cumulative incidence rates showed an annual peak during late summer and early autumn; maximum peaks typically occurred during July. STEC O157 infections exhibit highest rates during September to October, whereas STEC O26 reports peak in July. Urban cases had an annual peak from July to September, while rural cases had a longer but decreasing peak from May to October.

Cases attributed to secondary infection such as person-to-person transmission and those originating outside Ireland were excluded.

Markedly higher case numbers were found among children younger than 5 years of age with 1,101 confirmed cases. There was a significant association between STEC O26 infection and the younger than 5 category. People older than 65 years old were also disproportionately affected, accounting for 462 cases. Females were slightly more affected than males.

Infections among the younger than 5 year subpopulation peaked from May to July, whereas cases among older people occurred in July to August, followed by a smaller secondary peak in October.

Mitigating taeniasis
Meanwhile, another study in the same journal, has demonstrated that Taenia solium control can be achieved by using existing technology.

Taeniasis is a parasitic infection that can be caused by Taenia solium (pork tapeworm). Humans can become infected by eating raw or undercooked pork. Symptoms are usually mild or nonexistent but Taenia solium infections can lead to cysticercosis, which is a disease that can cause seizures and muscle or eye damage. Tapeworms can cause digestive problems including abdominal pain, loss of appetite, weight loss, and upset stomach.

Scientists conducted a two-year cluster randomized trial in 2015 to 2017 in Peru by assigning 23 villages to one of three geographically targeted interventions.

For ring screening, participants living near pigs with cysticercosis were screened for taeniasis; identified cases were treated with niclosamide. In ring treatment, those living near pigs with cysticercosis had presumptive treatment with niclosamide. In mass treatment, people received niclosamide treatment every six months regardless of location.

Researchers found targeted delivery of niclosamide to treat and prevent human taeniasis in a ring strategy and uniform delivery in mass drug administration both effectively reduced Taenia solium transmission. There was also significant reductions in seroincidence among pigs with all approaches.

They added that human taeniasis prevalence findings at the end of the study should be interpreted with caution because a baseline measurement was not taken. A total of 7,248 of 8,873 people accepted treatment and 6,537 provided a post-treatment stool sample. The unadjusted prevalence of taeniasis was 17 of 2,349 in ring screening, 29 of 2,206 in ring treatment, and 8 of 1,977 in mass treatment.

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