Rats beat dogs for diagnosing infection
Volume 9, Issue 25 | June 27, 2024
Also in This Issue
Human sniffs out Parkinson’s
Experts call for earlier gestational diabetes screening
Bird flu update: Michigan tests for asymptomatic human cases
Requesting Alzheimer’s diagnosis from PCPs is a big ask
New and Noteworthy
When it comes to sniffing out infection, rats have dogs by the tail
We love dogs and have reported in the past on their ability to detect COVID at least as accurately as the average antigen test. But another species might have the upper paw when it comes to sniffing out disease.
A Nature Outlook on diagnostics (which also contains a good bibliography of recent Dx-related research across all Nature publications) highlighted African Giant Pouched Rats’ ability to detect tuberculosis. These rats have an even better sense of smell than dogs do (100,000 more sensitive than nearly all humans). They’re also much smaller, easier to train and manage, and can perform tests much faster than dogs - 100 tests in 20 minutes, with a sip of banana avocado smoothie as a reward. And they deliver good accuracy (positive predictive value of 81%). When multiple (5 - 10) rats are used to test a single sample, accuracy even can increase even further.
Commentary: Working with animals for clinical tests is unlikely to be realistic in the short term. However, there are sweet spots where the benefits animals provide are justified. Dogs are useful for low-prevalence mass screening, e.g., in airports but require dedicated human supervision. Rats, on the other hand, require no skilled supervision after training but the squeamish factor remains. Most people would rather see the trained golden retriever. But don’t get excited - a home self-test is not on the horizon.
Her nose can diag . . . nose Parkinson’s
Dogs and rats have extraordinary olfactory senses, but are there people with similar abilities? We were intrigued by a New York Times story about a woman who can smell Parkinson’s disease (PD) in its very early stages, when symptoms are either absent or so vague that they could be caused by any number of disorders or even by simple fatigue.
After convincing researchers to test her skill in blinded studies, she passed with flying colors. Ultimately, scientists were able to identify what she was smelling: distinct compounds in the sebum of PD patients, mostly from the oil secreted at the back of the neck.
Commentary: Are there others like her? Probably a few. But once the compounds are known, could a more traditional test identify those compounds and be considered a definitive early diagnosis? We are highly cautious but optimistic. In the Diagnostics Year in Review, Mara identified the use of alternative samples as a key trend in diagnostics. We expect more to come here.
A global call for earlier gestational diabetes screening
Gestational diabetes is the most common medical pregnancy complication worldwide, affecting one in seven pregnancies, and it’s becoming more and more common. At-risk folks are typically screened for the disease between 24 and 28 weeks of gestation, even though research has shown both that earlier diagnosis and treatment lead to significantly better outcomes. This week, a global group of endocrinologists published a series in The Lancet calling for screening to begin between weeks 10 to 14, as up to 70% of cases can be diagnosed by the end of that time period.
Bird flu update: MI tests for asymptomatic human cases
Michigan is testing people who work with infected cows to see if they have antibodies to H5N1. The goal: To see if humans can get asymptomatic infections.
A new study demonstrated that infectious virus can persist on milking equipment. The virus “remained infectious in unpasteurized milk on stainless steel” for at least an hour and persisted on the kind of rubber used in milking machines for at least three hours.
The FDA has broadened its testing of retail dairy products, gathering a wider array of samples from more states than were included in its previous tests. This round of testing covers about 155 different products, including pasteurized milk, raw and pasteurized cheeses, cream cheese, butter, and ice cream.
The US Administration for Strategic Preparedness & Response (ASPR) published its response to bird flu on Friday. As part of this response, ASPR is offering personal protective equipment (PPE) to people who work with infected cattle. It also has Tamiflu available for areas that don’t have their own. The USDA secretary has urged dairy workers to use PPE when working with infected cattle, to increase cleaning measures on farms, and to limit traffic between farms.
Food for Thought
Want PCPs to diagnose Alzheimer’s? That’s asking a lot
Now that FDA-approved drugs for Alzheimer’s disease exist (albeit with limited effectiveness and severe side effects), patient demand for testing is growing. The trend isn’t limited to specialists - primary-care physicians (PCPs) are fielding these requests, too. But even the results of today’s simpler tests (e.g., blood-based tests for pTau217 and pTau212) require complicated, nuanced explanation. This week’s NEJM Perspective highlights how worried PCPs are about their ability and time to engage with patients on this topic.
Commentary: The range of tests for Alzheimer’s continues to widen. A small study published this week, for example, showed that an AI-trained model could use people’s speech patterns - the words they use and how they use them - to predict whether a patient with mild cognitive impairment would progress to Alzheimer’s within six years. But the positive predictive value of these tests when used for screening isn’t ideal. The AI model had an accuracy of 78.2% and a sensitivity of 81.1%; pTau is better, but not a universal slam-dunk. And understanding and communicating the nuanced criteria for prescribing one of the new drugs is not trivial. We agree with the Perspective’s authors: The current structure of primary care and reimbursement is inadequate to the emerging task (to put it mildly).
Quick Hits
A multinational group of researchers has created a probe that sends back images from inside the arteries in a patient’s brain. The probe fits inside the tiny catheters that clinicians use to treat the blocked arteries that cause strokes.
You know all those AI-enhanced imaging programs we’ve been talking about for the last year? According to CNBC, most of the nearly 600 AI / machine-learning enhanced radiology programs and devices aren’t covered by any insurance, because they don’t have billing codes. It can take seven years after FDA approval for payors to start reimbursing for a medical device. Until then, patients must pay out of pocket. Check your medical bills - and your wallets.
We are taking the next week to celebrate our democracy - and to relax. See you on July 11.