The Downside Of A Quick And Easy Malaria Test

SPEAKER 1: Now it’s time to play good thing bad thing.

[MUSIC PLAYING]

Because every story has a flip side. Now you probably know someone who has a home diabetes test. Maybe you do it yourself. You prick your finger. You put a drop of blood on a test strip. And you can get a readout of your blood sugar level almost immediately.

Now imagine if it was that simple to test for a deadly tropical disease. Well, in the case of malaria, it turns out it is. It’s called the Malaria Rapid Diagnostic Test– RDT. And it’s particularly useful in remote areas where traditional lab testing is difficult.

The test can confirm a positive reading, but the test comes with a few negative consequences. The results were published last month in the American Journal of Tropical Medicine and Hygiene. And Dr. Heidi Hopkins is an author on that study. She’s an M.D. And an associate professor in Malaria and Diagnostics at the London School of Hygiene and Tropical Diseases. Welcome to Science Friday.

SPEAKER 2: Thank you, Ira. Thanks for having me.

SPEAKER 1: You’re welcome. Let’s talk about the good thing first. Can you put in context how the introduction of this test has changed outcomes when it comes to treating malaria?

SPEAKER 2: That’s right. Well, as you were just saying, before we had diagnostic tests, a lot of these cases of malaria, which is a deadly disease, were being treated completely empirically. That means if you or your child has a fever, a health care worker says, you have fever. You have malaria. I’m not sure. We’re going to treat you just to be on the safe side.

And now we have the possibility, even in very remote areas, to diagnose more or less accurately those same fever cases. So the WHO estimates that now about half of children who are abroad for care in sub-Saharan Africa get a diagnosis as opposed to substantially less than that, even just a few years ago.

SPEAKER 1: That’s terrific. I imagine they’re very happy about that.

SPEAKER 2: You would think so. It does tend to get a positive reception.

SPEAKER 1: Now the test is very useful, as you say. But you conducted a study that showed that there were a few unforeseen consequences. And that’s the bad thing.

SPEAKER 2: Well, yeah. I’m not sure we want to say it’s bad, but there were definitely some big positive consequences to the introduction of RDTs. And We said now people with a potentially fatal disease can be diagnosed accurately. And in fact, this has improved the targeting of the appropriate antimalarial treatment, the artemisinin combination therapies that are first line drugs certainly across most of Africa, across most of the world. Now we can target them appropriately. And so the overuse of those has been appropriately targeted to the patients who do actually have malaria.

SPEAKER 1: Mhmm. And plus, there are some cases even when there was a positive outcome, the anti-malarials were not prescribed, correct?

SPEAKER 2: That’s right. So that was maybe the first of the unexpected and undesirable consequences that we noticed. There was a proportion of patients who, even though their test was positive and they had the symptoms of malaria– for whatever reason that’s not yet well understood– the health care workers decided to not give them an anti-malarial.

SPEAKER 1: And in cases where they wanted to give them drugs, they gave them– what– antibiotics, which wouldn’t do very much.

SPEAKER 2: In a lot of cases, especially when the test was negative, they did give antibiotics. That kind of makes sense. If you’re in a remote area and you don’t have a lot of other options– you’ve got a sick child or a sick patient in front of you, that person may have come from even up to 20 kilometers away with expensive transport or even walking– you want to do something. And if you don’t feel like you should give an anti-malarial– the test is negative– your alternative, in some cases, is an antibiotic.

SPEAKER 1: So what do we need to fill the gaps in the test here?

SPEAKER 2: Hmm, certainly, malaria tests diagnose malaria. But there’s hundreds of other things that can give a person the same symptoms. So we really need to do a better job of finding out what are those other infections and of developing diagnostics that can help health workers know when it’s not malaria, what is it.

SPEAKER 1: Quite interesting. Thanks for filling us in on this Dr. Hopkins. Heidi Hopkins, a medical doctor associate professor of Malaria and Diagnostics at the London School of Hygiene and Tropical Diseases.

Copyright © 2017 Science Friday Initiative. All rights reserved. Science Friday transcripts are produced on a tight deadline by 3Play Media. Fidelity to the original aired/published audio or video file might vary, and text might be updated or amended in the future. For the authoritative record of Science Friday’s programming, please visit the original aired/published recording. For terms of use and more information, visit our policies pages at http://www.sciencefriday.com/about/policies/