Mecosta becomes latest Michigan county to report CWD

News brief
White-tailed buck
Tidewater Teddy / Flickr cc

With the detection of chronic wasting disease (CWD) in a deer, Mecosta County becomes the 14th Michigan county to report the fatal neurodegenerative illness, the Michigan Department of Natural Resources (DNR) reported yesterday.

The buck was harvested in Millbrook Township in the west-central part of the state. Neighboring Montcalm County has reported 167 CWD cases. The DNR conducted intensive CWD surveillance in Mecosta County from 2017 to 2019, testing more than 5,600 deer but finding no positive cases.

"The expansion of CWD to Mecosta County is consistent with the slow spread we've seen throughout Michigan, especially since the CWD-positive animal was harvested near confirmed cases in adjacent Montcalm County," Chad Fedewa, MS, acting DNR deer, elk, and moose management specialist, said in the news release.

CWD, which affects cervids such as white-tailed deer, elk, and moose, is caused by infectious misfolded proteins called prions.

307 cases in state's free-ranging deer

After initial surveillance in areas near the first CWD detections in Michigan, the DNR began taking a rotational approach to testing in 2021. Each year, a group of counties is chosen, with the goal of testing deer in every county in the state.

The expansion of CWD to Mecosta County is consistent with the slow spread we've seen throughout Michigan, especially since the CWD-positive animal was harvested near confirmed cases in adjacent Montcalm County.

Chad Fedewa, MS

In 2021 and 2022, testing focused on the southwestern and southeastern Lower Peninsula. In 2023, the focus shifted to the northern Lower Peninsula, and in 2024, it moved to the northern Lower Peninsula and the Upper Peninsula.

Since CWD was first detected in Michigan wild deer in 2015, more than 109,000 deer have been tested. Since 2002, more than 143,000 wild deer have been tested through DNR surveillance, which identified 260 CWD-positive deer. More than 2,500 samples that hunters submitted to the Michigan State University laboratory since direct hunter submission began in 2020 have yielded another 47 cases, for 307 total CWD-positive deer.

In addition to Mecosta and Montcalm, counties with confirmed cases are Clinton, Dickinson, Eaton, Gratiot, Hillsdale, Ingham, Ionia, Isabella, Jackson, Kent, Midland, and Ogemaw.

No CWD infections have been reported in people, but the US Centers for Disease Control and Prevention recommends against the consumption of infected animals.

Experiments in monkeys show limited illness when exposed to H5N1 avian flu by mouth, stomach

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Cynomolgus macaques
Mangkelin / iStock

A series of experiments in monkeys suggest that drinking raw milk contaminated with highly pathogenic H5N1 avian flu is a risk for infection but may lead to less severe illness than respiratory tract exposure to the virus, researchers reported yesterday in Nature.

The study by virologists with the National Institute of Allergy and Infectious Diseases involved cynomolgus macaques who were exposed via three inoculation routes to the 2.3.4.4b clade of H5N1, the strain of the virus that's been circulating in US dairy cattle since last spring and has infected 40 dairy workers in four states, producing mostly mild illness. The route for cow-to-human transmission so far has been undetermined, and the researchers wanted to use the monkeys— a surrogate model for human infection—to investigate the pathogenesis of different routes of infection.

Using a dose of the virus that's close to what's been found in raw milk samples, the researchers infected 18 macaques, exposing 6 to the virus intranasally to mimic an upper respiratory tract infection, 6 via the intratracheal route (windpipe) to mimic a lower respiratory tract infection, and 6 via the orogastric route (mouth and stomach) to mimic consumption. After 14 days, they found that lower respiratory tract exposure caused systemic infection with severe pneumonia and upper respiratory tract exposure resulted in mild-to-moderate pneumonia. 

Limited infection

The macaques exposed via the mouth or stomach, however, had limited infection but showed no signs of illness. All the monkeys showed evidence for oral and limited nasal shedding, but shedding was higher and prolonged in those inoculated in the nose and windpipe.

"Overall, our study shows that lower and upper respiratory tract infection can lead to systemic virus replication, virus shedding and pneumonia with varying degrees of disease outcome," the study authors wrote. "In contrast, orogastric exposure led to virus infection, reduced virus shedding and subclinical disease."

The researchers caution, however, that their model is a surrogate for people drinking raw milk contaminated with H5N1. "To what extent it recapitulates human infection remains, as yet, unclear."

Tanzania health ministry reports negative test results in suspected Marburg virus outbreak

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Following a World Health Organization (WHO) alert 2 days ago about a suspected Marburg virus outbreak in Tanzania, the country's health ministry said yesterday that tests on collected samples were negative for the disease. The WHO had based its alert on reliable in-country sources.

patient sample testing
UNMEER, Martine Perret / Flickr cc

At a WHO briefing today, however, Director-General Tedros Adhanom Ghebreyesus, PhD, urged Tanzania's government send its samples for testing to international reference labs and to collect additional samples in accordance with normal procedures. He also said the WHO is supporting Tanzania's response and has offered to provide any additional support that is needed.

Index patient died in December; 300 contacts identified

Top officials from the Africa Centres for Disease Control and Prevention (Africa CDC) hosted their regular weekly telebriefing from Tanzania today and added more details about the outbreak, including that the suspected index case-patient is a 27-year-old pregnant woman who had an illness that progressed to hemorrhagic symptoms and died on December 16, 2024.

Jean Kaseya, MD, MPH, Africa CDC’s director-general, acknowledged official communication from Tanzania's government that no Marburg virus has been confirmed in lab tests. He said the government has Marburg virus test kits that were distributed as part of the regional response to Rwanda's Marburg virus outbreak last year. "We are supporting Tanzania. For now, this is the comment we can make."

A health worker involved in the woman's care became ill and died on December 27. So far, nine illnesses have been reported, and eight patients have died from their infections. Samples were collected from five patients.

So far, investigators have identified 300 contacts, including 56 healthcare workers. Africa CDC said 16 of the contacts had direct contact with sick patients.

If confirmed, the outbreak would be Tanzania's second Marburg event. In 2023, an outbreak in the same region resulted in nine illnesses, six of them fatal.

Study finds high pneumococcal carriage rate in healthcare workers

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A study of healthcare workers at a Connecticut hospital during the early months of the COVID-19 pandemic found that more than one in five were positive for pneumococcal carriage, researchers reported yesterday in Open Forum Infectious Diseases.

The study, conducted by researchers at Yale University, evaluated carriage of Streptococcus pneumoniae in a convenience sample of medical staff at Yale New Haven Hospital who had enrolled from March 30 to June 11, 2020, in a study that was initially designed to actively monitor asymptomatic healthcare workers for SARS-CoV-2 infection. Using the stored, self-collected saliva samples from that study, the researchers extracted DNA and tested it for the presence of pneumococcal-specific genes piaB and lytA. Samples were considered positive when the piaB cycle threshold (Ct) value was less than 40.

Of the 525 participants who enrolled in the study, samples from 392 participants (mean age, 38.7 years; 74% female; 73% white) were selected to test for pneumococcus. Overall, 138 (11%) of 1,241 samples from 86 (21%) of 392 individuals tested piaB-positive during the 4-month study period, with 28 (33%) of 86 colonized individuals positive at multiple time points. Positive individuals reflected the overall study population. Analysis of pneumococcal serotypes found colonized participants primarily carried serotypes 19F (25.6%) and 3 (12.8%), both of which are targeted by the PCV13 vaccine, which covers 13 pneumococcal strains.

'Unrecognized reservoir' of pneumococcus

The study authors note that the 21% prevalence of pneumococcal carriage observed in the study was at a time when strict non-pharmaceutical interventions for COVID-19 (such as masking) were in place and largely adhered to in healthcare settings, and global incidence of invasive pneumococcal diseases had declined. They suggest the rate could be higher post-pandemic, now that those mitigation measures are no longer in place and typical annual circulation of respiratory pathogens has returned.

"This study highlights that healthcare workers may act as unrecognized reservoirs of pneumococcus in the population," they concluded. "Despite longstanding pediatric immunization programs, vaccine-targeted serotypes continue to be prevalent among the adult population."

Elk becomes first CWD-positive case of its species on a Wyoming feeding ground

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Elk at feeding ground
Baker County Tourism / Flickr cc

An elk found dead on the Scab Creek Feedground in Elk Hunt Area 98 in Wyoming at the end of December has tested positive for chronic wasting disease (CWD), the Wyoming Game and Fish Department reported yesterday.

The hunt area, located in the Pinedale region in Sublette County, abuts three other CWD-positive elk areas: 28, 92, and 127. Sublette County is located in the west-central part of the state. This is the third reported CWD case in the hunt area and the first positive elk on a Wyoming feeding ground. 

"Scab Creek feedground will be included in the Department’s first Feedground Management Action Plan (FMAP) process this year," the DNR said in a news release. "This process will explore both long-term and short-term opportunities to reduce elk reliance and disease transmission risks on feedgrounds."

Experts fear illness could one day infect people

CWD, a fatal neurodegenerative disease caused by misfolded proteins called prions, can spread among cervids like deer, elk, and moose and through environmental contamination. The disease isn't known to infect people, but experts fear it could cross the species barrier. 

The Centers for Disease Control and Prevention cautions against eating meat from an infected animal or handling the carcass without taking precautions.

 

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