Doctors and community workers who have battled against a third world disease in New Zealand for decades have been given a glimmer of hope.
Against the odds, the number of rheumatic fever cases have fallen sharply in New Zealand in the last two years.
But the trend is an uneven one and it is not yet known what caused it. Hospitalisation rates for the potentially deadly disease have decreased significantly among only one group: Pacific households in Auckland. Māori rates have stayed relatively steady.
"Everyone is a bit baffled by it," said Associate Professor Collin Tukuitonga, from the University of Auckland's Medical and Health Sciences Faculty.
Tukuitonga said that if anything, acute cases of the disease were expected to rise during the Covid-19 pandemic because overcrowded housing - a risk factor for the disease - increased during the successive lockdowns.
"The theory that it's to do with better housing or less overcrowding doesn't really hold water. Because if we look at the experience with Covid-19, it appears that overcrowding, crowding multi-generational households, certainly in the Pacific communities seems to have gotten worse, not better."
The other confounding factor is the change only occurring within Pacific communities.
Professor Michael Baker, an epidemiologist from the University of Otago, said one of the more likely theories was that the closure of borders in March 2020 prevented extended families in the Pacific Islands from travelling to New Zealand.
"It might have altered somehow the dynamics of how strep was circulating," Professor Baker said.
This theory can't be confirmed without a larger, specific study. And while closing borders isn't a viable long-term solution, further research could at least inform the public health response.
Baker said the fall in acute cases was causing "considerable interest" among researchers who had followed the disease for decades.
"At this stage no one seems to be brave enough to really commit to any particular idea. But it was such a dramatic drop - it is something that we obviously will be interested in studying because it achieves something that several years of very intensive prevention programs didn't."
Public health medicine specialist Dr Nick Eichler, who focuses on rheumatic fever, said all of the Covid-19 restrictions were designed to control infectious diseases so it made sense that other communicable disease rates could also fall. Flu, RSV, measles, meningococcal rates have also dropped over the same period.
"It is a question of figuring out if the change is entirely real or is it a problem in access to care?" Dr Eichler said.
He added: "I don't think we can assume this problem is fixed … but it is a really golden opportunity to understand why our rates might have been high in the past and what changed."
Rheumatic fever is caused by an untreated bacterial infection in the skin or throat and can lead to heart disease or even death. Māori and Pacific children and teenagers make up nearly all of the cases and it is often cited as one the clearest examples of health inequity in New Zealand.
The persistence of the disease in this country has been called a national shame because it is closely associated with poor housing and poverty. New Zealand is just one of just two developed countries where it has any foothold at all.
Researchers cautioned against celebrating the reduction in hospitalisations or drawing definite conclusions too quickly.
Acute rheumatic fever was a rare condition and numbers could fluctuate year to year, often without a clear reason. And a minority of people who got the disease were ever diagnosed.
Dr Dianne Sika-Paotanu, an immunologist at the University of Otago, said vulnerable people may have struggled to access healthcare during lockdowns.
She said it was crucial that anyone with the condition was diagnosed quickly. There was no vaccine for rheumatic fever, and anyone who had contracted it needed to start monthly injections of penicillin to prevent further infection and heart complications.
The Ministry of Health is commissioning work to understand the factors that contributed to the decrease of rheumatic fever rates. That work would begin in the middle of the year, a spokeswoman said.
'It shouldn't be happening'
Matt Johnson, a former professional rugby and rugby league player, was diagnosed with rheumatic fever at age 13.
It was only picked up when he was concussed during a game and doctors noticed a heart murmur. It later ended his sporting career at age 26.
Johnson said the disease was a lifelong burden. He has had three surgeries for heart complications, including open-heart surgery which has left a long scar on his chest.
He had monthly penicillin injections for eight years and still takes five medications every day.
"Medications to look after the ticker, blood thinners, antibiotics, and things like that, daily, non-stop, until the end," he told the Herald. "I need to be extra cautious about certain cuts, the way I bleed, and certain bacteria that could possibly go into my bloodstream. I have to be vigilant."
Johnson, now 28, is a PE teacher at his old school, St Peter's College, and while he cannot play rugby he is able to coach it. He advocates for rheumatic fever prevention for the charity Cure Kids, which has put $3 million into researching the disease.
Johnson is heartened that rheumatic fever rates have fallen in New Zealand, even if the reasons are unclear.
"I believe it shouldn't be happening here in New Zealand. It's a third world disease."