A new analysis suggests the incidence of diarrhea caused by the norovirus, as well as the incidence of clostridiodes difficile infections (CDI) is low in long-term care facilities in Japan.

A team, led by Asae Suita, Department of Public Health, Osaka City University Graduate School of Medicine, identified the incidence rate and risk factors of norovirus-related diarrhea at geriatric intermediate care facilities.

Outbreaks in Care Facilities

Currently, norovirus is the leading cause of acute viral gastroenteritis outbreaks. In addition, norovirus outbreaks occur at 3-45% of long-term care facilities.

Due the nature of residents at care facilities, patients infected by the norovirus have an increased risk of developing serious conditions, including dehydration, pulmonary aspiration of vomitus, and mortality.

There is not much data on the risk of infectious diarrhea in a population of elderly residents at Japanese geriatric intermediate care facilities. M but a previous study found a case fatality rate of the institutionalized elderly to be 0.3-1.6%.

In the prospective cohort study, the investigators followed 1727 residents between November 2018 and April 2020 at 10 geriatric intermediate care facilities in Osaka. Each patient was evaluated for the occurrence of diarrhea.

Collecting Data

The investigators collected data using medical records from structured forms at 2-3 time points, including at recruitment, if they developed diarrhea, and when they left the facilities. They also tested patients who developed diarrhea for Clostridioides difficile, which is also a potential pathogen in care facilities.

Each staff member completed a structured form for residents including sex, age, underlying diseases, care-needs level, activities of daily living grade, level of cognitive dysfunction, number of roommates, history of hospitalization in the previous year, tube feeding, pad usage, independence in walking, and prescription drug use.

The participants who developed diarrhea were then tested for norovirus using a rapid diagnostic test. The team also used Cox proportional hazard model to estimate the risk factors for norovirus-related diarrhea.

Positive Results

Over the course of the study, 74 residents developed diarrhea. Of this group, 13 tested positive for the norovirus.

The incidence rate of norovirus-related diarrhea was 10.11 per 1000 person-years (95% CI, 4.61-15.61).

The investigators also found individuals with level 3 care needs were at a higher risk of developing norovirus-related diarrhea (aHR, 7.35; 95% CI, 1.45-37.30), as were participants with hypertension (aHR, 3.41; 95% CI, 1.05-11.04) or stroke (aHR, 8.84; 95% CI 2.46-31.83) and residents who used canes (aHR, 16.68; 95% CI, 1.35-206.52).

“Throughout the study period, the incidence of development of diarrhea was low,” the authors wrote. “Care-needs level 3, stroke, hypertension and use of a cane were identified as risk factors for norovirus-related diarrhea in Japanese geriatric intermediate care facilities.”

The study, “Incidence and risk factors for norovirus-related diarrhea in Japanese geriatric intermediate care facilities: A prospective cohort study,” was published online in Geriatrics & Gerontology International.