Today in Morbidity and Mortality Weekly Report, researchers in Wisconsin show how during the 2022-23 respiratory diseases season, high concentrations of influenza A virus and respiratory syncytial virus (RSV) in wastewater samples in three Wisconsin cities preceded virus-associated emergency department (ED) visits.

The authors say the study provides more evidence that wastewater surveillance can detect viral signals earlier than other surveillance methods.

Samples from 40 treatment plants

Wastewater testing rose in prominence during the COVID-19 pandemic, as detections accurately predicted spikes in viral activities in communities. In the present study, researchers collected wastewater samples from 40 treatment plants in Wisconsin’s biggest cities—Milwaukee, Madison, and Green Bay—at least once per week from August 2022 through March 2023.

ED visit data was linked to patients with a Green Bay, Madison, or Milwaukee residential zip code. A total of 6,271 flu-associated ED visits and 1,518 RSV-associated ED visits were reported from August 2022 to March 2023.

Wastewater surveillance might help supplement established clinical surveillance for these viruses.

The authors found a positive correlation between wastewater surveillance and ED visit data, with detections increasing in the 1 to 2 weeks before a rise in clinical cases was observed. Moreover, viral shedding occurred in wastewater samples for up to 3 weeks after the viruses peaked in communities.

"RSV peaked in early November, and influenza peaked approximately 1 month later," the authors wrote. "The positive correlation between wastewater surveillance and ED visit data for both influenza and RSV, along with the detection of the two pathogens in wastewater before increases in associated ED visits, suggests that wastewater surveillance might help supplement established clinical surveillance for these viruses."

In the latest in a deadly outbreak of Nipah virus infections in Kerala, India, a 24-year-old healthcare worker who was exposed to a Nipah patient has tested positive, according to the Hindustan Times and other media sources. The newest infection in Kozhikode district raises the outbreak total to five cases, two of which have proved fatal.

Officials are tracking as many as 706 people on the contact list, with 77 listed as high risk and 153 as healthcare workers who are not in the high-risk category. The government has advised high-risk contacts to remain inside their homes, and 13 people are hospitalized under observation with mild symptoms, NewsBytes reports.

Avian Flu Diary, an infectious disease blog, says tests on 11 people are pending.

Young boy in ICU

Kerala Health Minister Veena George said officials have ordered monoclonal antibody therapy to treat a 9-year-old boy with Nipah who is on a ventilator in the intensive care unit in Kozhikode district. It is the only available antiviral treatment for Nipah virus infection, though it has not been clinically proven, George said.

"We have ordered the monoclonal antibody with the ICMR (Indian Council of Medical Research) and it would be brought to Kozhikode soon. The imported medicine is already available with the ICMR," she said.

We are focusing on tracing contacts of infected persons early and isolating anyone with symptoms.

The outbreak, which began August 30, is Kerala's fourth Nipah outbreak since 2018 and has resulted in authorities' declaring containment zones in at least eight Kozhikode villages.

"We are focusing on tracing contacts of infected persons early and isolating anyone with symptoms," George told reporters. She said the virus detected in Kerala is the same as one confirmed earlier in Bangladesh, and it spreads from human to human with a high death rate but is typically less infectious.