Disease Prevention

In terms of public health, prevention is any action that reduces or eliminates the onset, causes, complications or re-occurrence of a disease or ill health [1].

ARF and RHD can be prevented at a number of different stages. Primordial and primary prevention aim to stop the development of ARF, while secondary and tertiary prevention aim to limit the development or progression of RHD and its complications.

Primordial prevention refers to any action aiming to minimise the presence of risk factors within a population, so in this case to prevent streptococcal infections within the Indigenous population [2].
Primary prevention aims to avoid manifestations of the disease, including the need to diagnose individuals at risk of streptococcal infections (typically children aged 5-14) and commence antibiotic treatment with penicillin [1,2,3].
Secondary prevention involves early detection of the disease and prompt treatment to inhibit its progression [2,3]. This also includes improving the delivery of treatment and patient care, providing information to the patient and their family or community, coordinating available health services and advocating for necessary resources [3].
Tertiary prevention is the last stage of intervention and aims to reduce complications and further disability once a disease is established [2].

Before going on, it is necessary to introduce a new term - "prophylaxis". What is prophylaxis? Prophylaxis refers to any means that are taken to prevent a disease, such as immunisation against whooping cough in children [2].

The image below summaries each form of disease prevention, with examples of how it may be applied. While each form of prevention acts at a different level of disease progression (indicated by the arrows), effective action against ARF and RHD will require a combination of approaches from every stage.

Primordial prevention represents the ultimate goal in eradicating ARF and RHD. It directly tackles the socieconomic and geographical barriers faced by Indigenous Australians such as overcrowding, poor sanitation and limited medical care. This is an area of prevention that is not well addressed by current Australian control programs and is explored further in the video below:

References

[1] East Mediterranean Region Office. Health promotion and disease prevention through population-based interventions, including action to address social determinants and health inequity [Internet]. Geneva: World Health Organisation; 2017 [cited 2017 Feb 17]. Available from: http://www.emro.who.int/about-who/public-health-functions/health-promotion-disease-prevention.html.

[2] Australian Institute of Health and Welfare. Rheumatic heart disease and acute rheumatic fever in Australia: 1996-2012 [Internet]. 2013 [cited 2017 Feb 17]; AIHW cat. no. CVD 60. Available from: http://www.aihw.gov.au/WorkArea/DownloadAsset.aspx?id=60129542747.

[3] RHD Australia. How is it prevented? [Internet]. Casuarina, NT (Australia): RHD Australia; 2016 [cited 2017 Feb 17]. Available from: http://www.rhdaustralia.org.au/how-it-prevented.

[4] Carapetis J, Brown A, Maguire G, Walsh W, Noonan S, Thompson, D. The Australian guideline for prevention, diagnosis and management of acute rheumatic fever and rheumatic heart disease (2nd edition). Casuarina: Menzies School of Health Research; 2012.

[5] Parnaby MG, Carapetis JR. Rheumatic fever in Indigenous Australian children. J Paediatr Child Health. 2010;46:527-33.

[6] Danchin MH, Curtis N, Nolan TM, Carapetis JR. Treatment of sore throat in light of the Cochrane verdict: is the jury still out? Med J Aust. 2002;177:512-5.

[7] McDonald M, Currie BJ, Carapetis JR. Acute rheumatic fever: a chink in the chain that links the heart to the throat? Lancet Infect. Dis. 2004;4:240-5.

[8] Carapetis JR, Brown A, Wilson NJ, Edwards KN. An Australian guideline for rheumatic fever and rheumatic heart disease: an abridged outline. Med J Aust. 2007;186(11):581-6.

[9] RHD Action (AU). Prevention overview [Internet]. Sydney, NSW (Australia): RHD Action (AU); 2017 [cited 2017 Feb 17]. Available from: http://rhdaction.org/prevention/prevention-overview.

Primary prophylaxis entails treating streptococcal sore throat with antibiotics, most commonly penicillin, in an effort to prevent episodes of ARF that would otherwise occur [5,6]. Unfortunately, attempts to systematically introduce primary prophylaxis through school or community-based sore throat swabbing or treatment programmes have not paved the way for proven or cost-effective reductions in ARF incidence [7]. Clearly a renewed effort to find a suitable strategy for primary prevention at the population level is essential!

Secondary prophylaxis is the only current control method that is cost-effective in Australia and is regarded as the best methods for reducing the incidence of RHD and its complications [4]. It demands that people with a history of ARF and RHD undergo long-term antibiotic treatment to prevent further streptococcal infections and recurrent episodes of ARF [5]. The most common antibiotic used for secondary prophylaxis is benzathine penicillin G (BPG), which requires 3-4 weekly intramuscular injections for at least 10 years after an ARF episode [2,5]. Given the nature of this treatment, the greatest challenge to secondary prophylaxis is ensuring high-level adherence. Patients living in NT average less than 50% of their scheduled injections and very few attain the recommended benchmark of receiving 80% of their scheduled injections [2]. Indeed maintaining adherence has become a major focus of register-based control programs [5]. The challenge of low adherence could be overcome by:

Improving the relationship between health staff and patients (and their families).
Utilising the expertise, experience, community knowledge and language skills of Indigenous health care workers to provide cultural training to non-Indigenous people working in the region.
Improve the quality and delivery of health education to staff, patients and families.
Develop and implement recall and reminder systems to accommodate individuals who are a part of high mobility groups.

Adherence is substantially better in health centres where there is a system of active follow-up when BPG doses are missed [8].

The Role of Research in Prevention!

Population-level strategies to eradicating ARF and RHD include research to understand the genetic and autoimmune mechanisms of each disease [9].

With an improved understanding of disease process comes the potential to develop new therapies for prevention and treatment. This has already seen the emergence of echocardiography screening for the early diagnosis of RHD [9].

Ultimately, a vaccine could be created against the streptococcal infection, holding the power to dramatically decimate the number of new cases of ARF and RHD through vaccination programs - something which has already been achieved with other illnesses such as poliomyelitis!

Posted 17th February, 2017

Note: Video created using VideoScribe software: http://www.videoscribe.co/