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Medical News & Perspectives
April 24, 2019

Wild Health: Dogs and Bats and Chickens, Oh My!

JAMA. 2019;321(18):1756-1757. doi:10.1001/jama.2019.2026

Wild Health offers an occasional look at the animal kingdom’s contributions to human health.

The comforting nudge of a wet nose, glow-in-the-dark bats, and chickens that lay eggs containing human proteins have made their mark in recent studies.

Canine Antidote for Anxiety

Emergency department (ED) patients with low-risk chest pain can be an anxious lot, but many ED physicians offer no anxiolytics. They’re concerned that patients might feel they’ve been labeled as anxious and their ailments won’t be taken seriously.

But now researchers have reported in PLOS One that they may have a solution to calm these patients: therapy dogs.

Investigators at the Indiana University School of Medicine and the Center for the Human-Animal Bond at Purdue University compared therapy dog visits with usual care among 80 ED patients at downtown Indianapolis’ Sydney & Lois Eskenazi Hospital, which has an animal therapy department.

More than half of patients in each of 2 study groups sought emergency care for chest pain, another type of pain, or a psychiatric condition but didn’t require immediate attention. While patients in the therapy dog group met with the dogs and their handlers for about 15 minutes, those in the control group received usual care for the same duration. All patients were evaluated for anxiety, depression, and pain 3 times—before care, half an hour after a dog visit or usual care, and shortly before their discharge.

Compared with patients in the usual care group, those who saw a therapy dog had a 35% lower anxiety level 30 minutes after the encounter, and the lower level lasted through the third evaluation. Patients in the therapy dog group also had significant decreases in pain and depression compared with patients who received usual care. In addition, 2.5% of patients in the therapy dog group compared with 17.5% of those in the usual care group received opioid pain medication after the interventions.

Glowing Bats Show Spread of Disease

Hibernating bats covered with brightly colored fluorescent dust have helped a team of researchers learn more about how epidemics spread. Their study in the journal Nature showed that it’s not necessarily sick friends, family members, or others in close proximity who will give you the latest bug. Easily overlooked contacts, like a stranger sitting next to you on the bus, can be potent factors in fueling disease transmission.

Joseph Hoyt, PhD/Virginia Tech

The researchers refer to these seemingly unimportant casual contacts that nevertheless spread infections as “cryptic connections.” To study how they drive an epidemic, the researchers dusted 3 species of bats hibernating in 8 abandoned mines in Michigan and Wisconsin. Over 5 winters they documented how the bats mingled within and outside of their own species as well as groups that hibernated together. By tracking their dust marks, which served as surrogate pathogens, the researchers analyzed how the bats’ interactions might transmit white-nose syndrome, a fungal infection that has killed 6.7 million bats in North America since 2006.

Dust-spot patterns observed before any bats were infected suggested that the fungus would spread rapidly in some species but not others. When the fungus arrived, that’s what happened. In the first year that infections occurred, the mean prevalence was 84% in 2 species but below 25% in another. Analysis of the dust spots showed that transmission rates were better explained by the total number of contacts among bats, especially their extensive cryptic connections, than by contacts within species or hibernating groups.

“Cryptic connections not only link social groups within species but also create bridges among species, resulting in highly connected communities and explosive epidemics,” such as the 2014 Ebola epidemic in West Africa and Nipah virus transmission in Bangladesh in 2004, the authors wrote.

Birds as a Bioreactor

Researchers in the United Kingdom reported in BMC Biotechnology that they’ve genetically modified chickens to produce eggs containing human proteins that could aid in developing cost-effective therapeutic antibodies.

The investigators focused on 2 proteins: human interferon-α 2a, a cytokine used to treat hepatitis and various cancers, and colony-stimulating factor 1 (CSF1), a cytokine involved in macrophage differentiation, proliferation, and function that’s considered a therapeutic candidate in regenerative medicine. They used lentivirus vectors to create lines of transgenic hens that produced eggs containing human interferon-α 2a as well as human and pig versions of CSF1.

The egg-derived proteins exhibited purity and bioactivity equal to or better than those generated by traditional cell culture or Escherichia coli systems. The hens experienced no ill effects.

Traditional therapeutic protein production methods—including those in milk from transgenic sheep, goats, and cows—are often expensive, complex, or can cause adverse effects in the animals involved, according to the investigators.

However, chickens’ upkeep is relatively inexpensive, they reproduce quickly, and their eggs’ protein yield is high—an average-size egg contains almost 3.5 g of protein per egg white. Given the demand for protein-based therapeutics and their significant cost, the investigators wrote that their research “could lead to more affordable treatments and wider markets, including in developing countries and for animal health applications.”

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