Evaluation of ultrasound as an alternative to chest radiography for the diagnosis of tuberculosis in Papua New Guinea

In 2020, according to the World Health Organization, 1.5 million people died of tuberculosis. Papua New Guinea (PNG) has one of the highest TB prevalence rates in the world, with 30,000 new cases reported each year(1). Médecins Sans Frontières (MSF) has been involved in TB care in PNG since 2014. In collaboration with the National Department of Health, MSF staff are providing diagnosis and treatment to TB patients in Port Moresby at two clinics: the Gerehu General Hospital (for drug susceptible TB and Drug-resistant TB) and the newly opened 6 Mile Clinic (only for drug susceptible TB). MSF also runs an awareness program to prevent the spread of the disease.

“Tuberculosis is a treatable and curable disease. But this requires several months of treatment and, above all, diagnosis. And this is one of the first difficulties,” says Dr Andrea Llamas, TB doctor of the project.

The WHO recommends the use of molecular tests, such as GeneXpert, which require a laboratory and have a relatively high cost.

"In low-income countries, a chest X-ray can be performed beforehand to select people to be referred to this molecular test, whether they have symptoms or are at high risk of tuberculosis," says Maria Lightowler, epidemiologist at Epicentre.

When the suspicion is confirmed by imaging, a sample is taken for analysis by GeneXpert.

Countries with a high prevalence of tuberculosis are often quite lacking of X-ray equipment, due to their cost and the need of qualified radiological personnel to handle them and interpret the images. New affordable portable ultrasound machines are now emerging as an alternative to chest radiography, especially as they can be used by trained clinicians. Although initial data, particularly from Sub-Saharan Africa (2), suggest a promising potential, weaknesses remain, such as operator-dependent variability and low specificity.

“We are conducting a prospective study to compare the results of ultrasound and chest radiography in the diagnosis of pulmonary tuberculosis in people15 years of age and older with suspected tuberculosis who are referred for diagnosis to the MSF clinic at Gerehu General Hospital", says Maria Lightowler.

Ultimately, several clinicians at the Geruhu clinic should be trained in the use of ultrasound. One clinician has already benefited from this 3-week training and a second is currently being trained. All patients eligible to participate in the study will have a lung ultrasound performed by one of these qualified clinical officers.

"We hope to increase knowledge about the potential for using ultrasound as a diagnostic technique for pulmonary tuberculosis in resource-limited settings," said Maria Lightowler. The study is expected to take 12 to 14 months to complete.

Early diagnosis of tuberculosis is a key element to improve management. If ultrasound confirms its added value in this field, it could greatly facilitate the identification of people to whom a molecular test should be proposed. The next step is to get the diagnosed people into a therapeutic protocol and to maintain them in it, because the length and constraint of tuberculosis treatments result in poor compliance, or even abandonment of the treatments.

Photo Credit: Sophie McNamara/MSF

1. https://www.who.int/fr/news-room/fact-sheets/detail/tuberculosis#:~:text=La%20tuberculose%20est%20pr%C3%A9sente%20dans%20toutes%20les%20r%C3%A9gions%20du%20monde,Pacifique%20occidental%20(18%20%25).
2.  https://www.sciencedirect.com/science/article/pii/S1201971222003988