Paediatric infectious diseases physician Dr Andrew Steer is passionate about improving heart health, particularly among Indigenous Australians and in developing countries where rheumatic fever and rheumatic heart disease remain a significant public health concern.
Dr Steer, from the Murdoch Children’s Research Institute, and his Scabies Research Team were recently awarded a prestigious Eureka Prize for their efforts to combat the scourge of scabies.
The mite has long been linked to skin sores that, when infected by Group A streptococcus (GAS), can lead to more serious soft tissue and blood stream infections, kidney disease and, potentially, to rheumatic fever and rheumatic heart disease (RHD).
Until recently it was thought that only some of the 250 types of GAS were rheumatic – typically those linked to sore throats – but Dr Steer told the limbic that ‘textbook’ teaching based mostly on US research was now being challenged by research in Australia and the Pacific.
“The connection between the scabies and RHD comes from experience particularly in the Northern Territory where rheumatic fever and RHD is very common but where sore throat is not particularly common. What is, though, is a lot of GAS skin disease in those communities.”
“The situation is very different in tropical countries versus more temperate climates like the US. We’ve shown there are many different types of GAS found in patients with rheumatic fever and when you look at tropical climates you see types of GAS associated with rheumatic fever that are also associated with skin disease. My view is that probably any GAS can be rheumatic – it’s just a matter of where in the world you are sampling.”
Dr Steer’s early work in Fiji highlighted the huge burden of disease – about 20% of the population had scabies at any one time, increasing up to 40% for children in the first five years of school. He also reported a similar disease burden in the Southern province of the Solomon Islands and in Australia among remote Indigenous communities.
Those findings set him on a trajectory to reduce the heavy disease burden via mass drug administration.
“The concept of mass drug administration to interrupt transmission is really part of a broader neglected tropical disease movement – a series of strategies supported by the World Health Organization to control the impact of different diseases. So we thought about that kind of approach using the drug ivermectin.”
The oral drug is already widely used for a number of other parasitic diseases. Two billion doses of ivermectin have been given to people in Africa for the control of river blindness or onchocerciasis.
From there the idea for the SHIFT (Skin Health for Intervention in Fiji) trial was borne. In the landmark trial, three Pacific Island groups were randomised to receive either mass administration of ivermectin, permethrin or standard care.
At baseline, all three communities had a disease prevalence of about 35%. At 12 months follow-up, prevalence had fallen by 50% with standard care, by 67% with permethrin, and by a dramatic 94% with invermectin.
“That was really exciting – essentially we showed that we could have high coverage that was feasible and effective and safe,” Dr Steer said.
But he said more work was needed to learn about ivermectin and the risk of resistance.
“Resistance to the drug in the scabies mite has been described but only in two patients in the NT. Those two patients had over 20 doses over a relatively short period of time and those were patients with a rare form of the disease called crusted scabies so we don’t envisage that it’s going to be a big issue but I think we do need to improve our efforts to monitor resistance.”
A similar trial, the Azithromycin Ivermectin Mass drug administration (AIM) trial, is underway in the Solomon Islands. Early findings suggest the approach can be rolled out on a larger scale (over 25,000 people) and is an effective and safe public health strategy when integrated with other mass drug administration programs.
Dr Steer said two separate NHMRC funded studies will establish whether one dose of ivermectin versus two yields better outcomes while another large study in collaboration with the Fiji Ministry of Health will investigate the impact of the intervention on the downstream complications of scabies such as rheumatic fever and RHD.
“This study will be really important to making a broader public health case for mass drug administration – if you control scabies you can also control these other diseases.”
“We should be aiming to eliminate scabies as a public health problem – that’s our aim. We still see occasional cases in more populated areas and we see outbreaks amongst residential communities like aged care facilities but it’s not a public health problem in major cities in Australia so what we are aiming to do is eliminate it using a simple, safe effective intervention in places where it’s endemic.”