The Michigan Department of Natural Resource (DNR) yesterday reported the first detection of chronic wasting disease (CWD) in a deer in Ogemaw County, which is in the north central part of the lower peninsula.

The deer was a 4-year-old doe that was skinny, drooled, and showed no fear of people. The University of Wisconsin Veterinary Diagnostic Laboratory in Madison confirmed the findings. CWD has now been found in 13 of Michigan’s 83 counties.

Chad Stewart, MS, the DNR’s deer and elk specialist, said intensive surveillance had been done. "In light of this new detection, we are offering additional opportunities for those interested in getting their deer tested for CWD in Ogemaw County," he said. Officials said a drop box for CWD testing will be available in the area starting November 3.

Rotational approach to testing

Stewart said CWD isn’t common in Michigan deer, and the hunting community continues to play a key role in helping with testing efforts. The DNR said it regularly tests around areas where CWD is detected as a way to detect the disease early. In 2021, it started a rotational approach, selecting a group of counties for testing each year with a longer-term goal of testing all Michigan counties.

The focus this year is counties in the northwestern lower peninsula and a few counties where more herd information is needed.

Michigan’s first CWD detection occurred in 2015, and, since then, more than 137,000 wild deer have been tested. The deer in Ogemaw County is the 251st to test positive.

CWD is a prion disease that causes neurodegeneration, similar to "mad cow disease," in several cervid species, or members of the deer family. The disease hasn’t been shown to jump to people, but health officials urge people to avoid eating infected animals and to use precautions, such as wearing rubber gloves and minimizing contact with brain and spinal tissues, when processing deer.

A simulation looking at coughing and droplet spread in cruise ship passenger cabins meant for two or more passengers shows that higher ventilation does not necessarily lead to the best viral protection. The study is published in Physics of Fluids.

Cruise ships became one of the first sites of COVID-19 outbreaks in the spring of 2020, with hundreds of passengers infected and then quarantined on the ships for days. In the new study, researchers simulated droplets produced by a cough in a typical cabin, and used computational fluid dynamics to test 1.5 to 15 air changes per hour (ACH).

Current recommendations for cruise ships focus on high ACH, 6 or more an hour, but the simulations showed that such frequent changes were energy inefficient, were uncomfortable for passengers because they generated air drafts, and spread droplets farther and faster during simulated coughs.

Passenger comfort considered

The researchers found an ACH of 3 when a cabin was occupied was the most effective and efficient. When a cabin was empty between occupants, an increase to 15 ACH for at least 12 minutes allowed for the most sanitary conditions.

In this way, contaminated droplets would spread at a limited distance from the infected person while the air would be completely refreshed for the next occupants.

"In this way, contaminated droplets would spread at a limited distance from the infected person while the air would be completely refreshed for the next occupants," the authors said. "The same minimum time of 12 min can also be proposed as a clearance wait time for similar-sized rooms with a minimum of 15 ACH."

In a press release on the study, author Dimitris Drikakis, PhD, said, "Complete evaporation of the saliva droplets may not necessarily mean all viruses or bacteria become instantly inactive. Therefore, we should aim at minimum droplet spreading inside the cabin and different ventilation strategies for occupied cabins."