Far fewer bat species carry viruses with high potential to cause disease epidemics in people than is widely assumed, researchers from the University of Oklahoma and Yale write in Communications Biology.

In fact, only certain types—especially those found in coastal South America, Southeast Asia, and equatorial Africa—harbor dangerous pathogens such as SARS-CoV-2, Marburg, and Nipah viruses, they found.

The team used advanced machine learning to identify groups of bat species most likely to host highly virulent and transmissible viruses.

"Characterizing host-virus associations is critical due to the rising frequency of emerging infectious diseases originating from wildlife," they wrote. "Past analyses have evaluated zoonotic risk as binary, but virulence, transmissibility, and death burden can vary dramatically." 

Role of human encroachment, habitat destruction

A total of 889 mammal species, including 202 bat species, carried 112 virus species from 23 virus families. The viral families Togaviridae and Flaviviridae contained the risky viruses most likely to be found in bats. Rhinolophidae (horseshoe bats) harbored the most-dangerous viruses, aligning with previous analyses.

We hope our analyses can aid in facilitating conversations highlighting the ways in which human activities, not bats inherently, drive zoonotic viral emergence.

The bat superfamilies Emballonuroidea and Vespertilionoidea, most of which can roost in human-made structures such as houses, may pose a higher risk for viral spillover to people. Identifying the wildlife species most likely to carry these viruses can help target surveillance and conservation efforts, which can be time- and labor-intensive and costly.

Human encroachment and bat habitat disruption can increase zoonotic viral spread by increasing interspecies contact and stressing bats, which may tax their immune systems and boost viral shedding, the authors reported. 

Culling bat colonies is not the solution, however, because this can increase viral prevalence in bats and amplify spillover risk. "We hope our analyses can aid in facilitating conversations highlighting the ways in which human activities, not bats inherently, drive zoonotic viral emergence," the researchers wrote.

Indeed, bats benefit ecosystems through, for example, pollination, seed dispersion, and agricultural pest consumption. "If we lost bats, agricultural production would be negatively affected, and so would economies," lead author Caroline Cummings, a doctoral student at the University of Oklahoma, said in a university news release.

The US Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) reported several new detections of highly pathogenic avian flu in poultry, including four major outbreaks on commercial turkey farms.

In Lamoure County, North Dakota, a commercial turkey farm with 24,700 birds was hit, and in Mcpherson, South Dakota, a facility with 63,800 birds was also affected. South Dakota also had a detection last week on a turkey farm with 56,300 birds in Spink County, as well. 

In Ottawa County, Michigan, 62,200 birds on a turkey farm were impacted. 

Table egg facility with 231,000 birds hit 

Elsewhere two large poultry outbreaks were reported in Lagrange County, Indiana. Two flocks were hit, affecting 43,800 birds total. 

Last week, California's Sonoma County reported a large outbreak at a commercial duck breeder farm, and now the same county reported an outbreak at a commercial table eggs layer facility, with 231,000 birds affected. 

Christ Hospital in Cincinnati is investigating two recent cases of Legionnaires' disease in patients in the past 6 week. Legionnaires' disease, a serious lung infection caused by Legionella bacteria, is contracted through inhaling contaminated water droplets.

Officials say they're working with local and state health departments to determine if the patients contracted the disease on Christ Hospital's main campus. So far the site of exposure is unknown, but the hospital has initiated environmental testing.

The bacteria that cause the atypical pneumonia live in natural and artificial water sources, and the hospital said it was testing all possible systems for contamination and installing new filters in hospital showers and faucets. 

Hospital officials told media that the risk to the public remains low.