Tackling scabies could reduce rheumatic heart disease across the Pacific - researchers

New research from Tonga finds children suffering from scabies and skin infections are up to five times more likely to show signs of rheumatic heart disease, with researchers saying that improving scabies treatment could help reduce the rates of one of the Pacific’s most preventable heart conditions.

The cross-sectional study of four Tongan primary schools that screened children for scabies, bacterial skin infection, and heart abnormalities. The results, published in the Journal of Paediatrics and Child Health, examined 400 children as part of Tonga’s Mafu Sai (Good Heart) programme, a long-running national screening initiative.

Speaking with William Terite on Pacific Mornings, Dr Simon Thornley, the study’s lead author from the University of Auckland, says the link between scabies, infection, and heart damage is compelling.

Thornley explains that scabies is caused by a microscopic mite, “about half the size of a pinhead”, that burrows into the outer layer of the skin. The intense itching and irritation lead to scratching, which breaks the skin and makes it easier for harmful bacteria to enter.

Thornley says the skin damage creates the conditions for infections such as staph and strep to take hold. Studies show these are common complications of scabies, particularly in Pacific communities.

“We know that strep in particular is very strongly associated with rheumatic heart disease. So we've got this link between scabies, skin infection, and then rheumatic heart disease. There’s certainly a very strong biologically plausible reason why scabies is important,” he says.

“Probably most importantly of all, we saw that the kids with the bacterial skin infection and scabies were about four to five times more likely to have thickened heart valves or rheumatic heart disease when the echocardiographers looked at their hearts,” Thornley says.

The research team reports the prevalence of scabies among children was 29.8 per cent, with impetigo at 20 per cent, and rheumatic heart disease at 4.5 per cent. Thornley says this research suggests that by adopting more aggressive treatment for scabies, rates of rheumatic heart disease could improve.

“All across the Pacific, we see high rates of scabies and impetigo in kids. So scabies is a really treatable condition. It can be completely reversed. So we think this is exciting in terms of turning around the burden of rheumatic heart disease.”

In a media release, Dr Gerhard Sundborn, Pacific health researcher at the University of Auckland, says Tonga’s biennial screenings offer a unique national overview of children’s heart health.

“Tonga screens all primary school children every two years for rheumatic heart disease as part of its Mafu Sai (Good Heart) programme. In 2023, some were also checked for scabies and skin infection,” Sundborn says.

In a press release, Mele Tilema Cama, a Tongan researcher at the Tonga National University, says the findings give hope after two decades of intensive screening under the Mafu Sai initiative.

“Our Mafu Sai programme has screened about 5000 primary school children annually. It’s resource-intensive but vital for early treatment. We are excited this research may offer a way to prevent rheumatic heart disease,” Cama says.

Watch Dr Simon Thornley’s full interview below.

Thornley says the findings are also relevant to Aotearoa, New Zealand, where Māori and Pacific children continue to bear the most burden of rheumatic heart disease. He says, “a greater focus on scabies is likely to improve the rheumatic heart disease issues here”.

In New Zealand, rheumatic heart disease affects one in 100 Māori children and two in 100 Pacific children, compared to one in 1000 nationwide. Scabies remains widespread but treatable across the region.

In a press release, Dr Aidan Hayes, a South Auckland urgent care doctor, says he was surprised to see many patients with scabies, often misdiagnosed and struggling to get effective treatment.

The research team recommends mass drug administration of ivermectin, which Thornley describes as “a very safe drug” that has been rolled out in various Pacific countries, including Fiji, Solomon Islands, Kiribati, and parts of Vanuatu.