6 July 2018

Make killer worm a notifiable disease

Clinical Public Health

Experts are pushing for a neglected tropical disease to be added to the Australian National Notifiable Disease List.

The parasitic roundworm, Strongyloides stercoralis, can live for decades inside the human body causing non-specific symptoms before suddenly becoming lethally hyperinfective.

There have been thousands of deaths worldwide from disseminated strongyloidiasis and numerous fatalities in Australia over the years. 

People die when the gut parasite ramps up its reproduction, sending larvae covered in enteric bacteria into other organs, which can result in septicaemia, meningitis or local sepsis. 

In around 65% of cases, the hyperinfective stage is triggered by high dose corticosteroids, which are often prescribed to treat the rash unknowingly caused by strongyloidiasis. The Northern Territory’s clinical guidelines now advise doctors to test for strongyloidiasis before prescribing corticosteroids.

Immunocompromised patients carrying S. stercoralis, such as those with diabetes, systemic lupus erythematosus, organ transplant recipients, are at risk of deadly parasite dissemination. However, most people with strongyloidiasis experience an acute phase, marked by diahorrea or other symptoms, and then suffer intermittent skin, respiratory, or gastrointestinal symptoms.

The disease is spread when human faeces are present in the environment, allowing larvae to burrow through the skin of the new host. Remote or rural communities with poor sanitation are at greater risk. 

Based on studies across northern Australia, strongyloidiasis appears to have a high level of prevalence in some communities, with rates ranging from 2% to 60%.

S. stercoralis is endemic in Indigenous populations in Australia, and is the fifth most common disease carried by returned travellers. 

“You can pick it up as a child, people can pick it up in their travels, and then effectively they are carrying that for a lifetime,” Wendy Page, a GP at Miwatj Health Aboriginal Corporation in the Northern Territory, said.

Dr Page began her long journey of advocacy when her colleague, an Aboriginal health worker in Adelaide, died from disseminated strongyloidiasis in 1999.

She is one of eight authors of a paper recently published in Tropical Medicine and Infectious Disease, which forcefully argues for the additions of strongyloidiasis to the Australian National Notifiable Disease List. 

“To determine whether a disease should be notifiable, there are currently 12 criteria against which a disease is ranked,” the paper states. 

The authors give strongyloidiasis a conservative score of 28, which is above the score of 25 which is required for a disease to become notifiable. 

Disseminated strongyloidiasis was added to the Territory’s notifiable disease register in 2011, after years of pressure from the National Strongyloidiasis Working Group.

“That only gives us the tip of the iceberg,” Dr Page said.

A spokesperson from the federal Department of Health told The Medical Republic that only a small number of people had the power to nominate a disease for assessment for addition or deletion from the National Notifiable Disease List.

This included members of the Communicable Disease Network Australia (CDNA), chief medical officers for the federal, state or territory governments, and ministers of health, among others.

“Currently there have been no nominations to CDNA for strongyloidiasis to be added to the National Notifiable Disease List,” the spokesperson said.