Carlo Perrone: Improving scrub typhus detection and prevention

My name is Carlo Perrone, I work in Northern Thailand, in Chiang Rai. There, I research mostly a disease called scrub typhus, which is transmitted by a very small bug that can be found near streams, rivers, forests, rice fields. When people enter these environments, they can get a disease called scrub typhus. This means normally it's people who live in agricultural, rural, remote communities that get it.

We are working on developing a diagnostic cartridge. So basically, we are developing a cartridge that detects scrub typhus. It's very simple to use, and it goes into a highly automated machine that gives a result in one and a half hours. The current point of care test is antibody based. That means it detects our reaction to the pathogen, and the body needs a bit of time to react, so in the first few days, they won't be detected, and then it will rise, and it will slowly go down. In the first few days and in the last days, the results will be wrong. In the first few days you'll have a false negative result, and in the last weeks, sometimes months, you may have a false positive result. By detecting the pathogen directly, these window periods where the tests perform badly can be avoided.

The big questions are developing rapid, accurate diagnostic tests that can be used away from large research centres, from small hospitals, which is where patients are likely to present, and also moving research away from large urban centres, and moving it towards communities, and working with communities to understand how they live and how we can help them in their environment.

At the moment, patients who develop scrub typhus go to a primary care unit near their homes, but they don't get treatment there and they don't get diagnosed there, because the awareness is very low. So, they will have to be referred to a larger hospital, which may take days, and in the meantime, the disease is left untreated, which causes complications, potentially death. By providing a rapid and easy diagnostic test, we will avoid this delay. This will save time to patients, money for transportation, and of course, avoid complication and death.

Scrub typhus is endemic from China to India, and Japan. Over a billion people are probably at risk. In Southeast Asia, it may be the most common treatable cause of fever for people who live in rural areas. We need to diagnose it quickly and effectively so we can estimate the true burden, and we need to involve communities to make sure they are part of the solution, and that is what we are trying to do in Chiang Rai.

This interview was recorded in January 2024