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Tackling the Communicable Diseases Challenge in New Zealand

Monday, May 1st, 2000
Dr Chris Bullen - Public Health Physician,
Dr Greg Simmons - Public Health Physician,
Kathy Pritchard - Manager Disease Management Team,
Auckland Healthcare Public Health Protection Service, Auckland, New Zealand



Introduction

Nowhere in New Zealand do communicable diseases present a challenge as great and acute as that in the Auckland region. In recent years, Auckland has witnessed major epidemics of meningococcal disease and measles and outbreaks of tuberculosis (TB).  1  ,   2  ,   3   In 1999, Auckland Public Health undertook contact chemoprophylaxis for 228 cases of meningococcal disease and investigated two major outbreaks of TB, with 20–30 cases involved in each.  4   Food-borne illness is also on the rise, each outbreak leading to an intensive investigation to identify a source.  5   Rheumatic fever, long considered by most Western health professionals to be a disease seen only in undeveloped countries, occurs in alarmingly high rates among Maori and Pacific Island people in New Zealand.  6   The risk of other "new" communicable diseases, such as some arboviral diseases, breaking out among Auckland’s population, is considered to be high and increasing.  7  

What are the drivers of these problems, and how might a mainstream Public Health Service respond? What criteria are used to prioritise public health action at a regional level? In this paper, these questions are addressed by first examining the current situation in Auckland, New Zealand and exploring the driving forces at work. We then consider current and possible strategies for strengthening public health action to prevent and control communicable diseases in the region, the policy, purchasing and legislative environments that constrain or empower the public health response and, finally, how prioritisation decisions are made.



Drivers and Status of Communicable Diseases in Auckland

Epidemiologists have traditionally analysed the determinants of communicable disease by considering the so-called "epidemiological triad" of host, agent (in this case, various micro-organisms) and environment. These factors clearly overlap and interact. Nevertheless, they provide a useful framework for this discussion.



Host Factors
Host factors are important in Auckland’s communicable diseases picture. Host factors include demographic characteristics, levels of immunity and behaviour.

With one-third of the nation’s population, Auckland dominates the national epidemiology. This dominance is likely to continue for some time. Each year, more than 10,000 people – the population of many provincial towns in New Zealand – are added to the region.  8   Many of these people are new arrivals from overseas. Others are added by natural growth. Among the most fertile sub-populations in Auckland are Pacific Island peoples, who also bear a disproportionate burden of many communicable diseases. Such demographic pressure will continue to be a leading driver of the communicable disease picture in Auckland.

Immune protection against infectious agents varies widely. Childhood immunisation coverage in Auckland is staggeringly low by any standards, and varies by ethnic group and sub-region. A survey conducted by North Health in 1996 showed that overall vaccination coverage (full immunisation at the age of two years) was around 63%. 9   Maori and Pacific Island children were less likely to be fully immunised (45% and 53% respectively, compared to 72% of others). The strongest risk factor for non-completion of immunisation was failure to have the first vaccinations on time at six weeks, this in turn relating to issues such as the cost of getting to a doctor, concerns about the painful nature of vaccinations and high family mobility (over 30% of families with a child aged 2–3 years in the survey had moved residence more than once since the child’s birth). This situation leaves the population vulnerable to epidemics, which have generally had the greatest impact on those who can least afford it. With many communicable diseases, protection for the few who are unvaccinated is provided by the many that are immune, so-called "herd immunity". In general, around 90% must be immune to prevent infectious diseases (for example, measles) taking hold and circulating.

"Risk" behaviours and lifestyles also contribute to the transmission of communicable diseases, although many of these behaviours are embedded in social environments that limit choices and restrict access to information on healthy practices. Such risk factors include unsafe sex, percutaneous exposures such as unsterile tattooing and body piercing or needle sharing among intravenous drug users. Unsafe food handling practices (eg, poor hand hygiene, time and temperature abuse) both in food premises and domestic settings also contribute to the spread of many communicable diseases. In 1999 Auckland Public Health investigated 185 outbreaks of illness associated with food premises.


Agent Factors
While migrants, returning travellers and other visitors may bring with them communicable diseases from their home country (eg, HIV and TB) or last stopover (such as dengue fever or giardia), most is in fact "home grown". The rising incidence of isolates of community- and hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) in Auckland is a growing concern.  10   New diseases are "emerging" and diseases once considered conquered are "re-emerging". The rapid emergence of verotoxigenic E. coli (VTEC) infection with its severe effects on the young in particular, is cause for concern.  11   The recent occurrence of a significant food-borne outbreak of VTEC in Australia  12   suggests that it is more likely to be a question of "when", rather than "if’", a similar outbreak will be experienced in New Zealand. The successful control of VTEC outbreaks requires rapid identification of cases, and prompt investigation and control of the source of infection.  13   This type of outbreak will test the mettle of the public health service.


Environmental Factors
Auckland’s socioeconomic environment is an important driver of communicable diseases. Social and economic deprivation correlates strongly with diseases such as TB, rheumatic fever and meningococcal disease. Auckland is also experiencing physical environmental stresses. There is insufficient affordable housing to accommodate low-income families,  7   contributing to overcrowding with its well-documented associations with TB and meningococcal disease. Auckland’s sewerage systems are inadequate, leading to contamination of recreational and traditional seafood harvesting waters by pathogenic organisms.  14  

The combined, interactive effect of these host, agent and environment factors is to provide a fertile soil in which communicable diseases thrive. This is likely to continue to do so for the foreseeable future. So long as the distribution of the underlying social and economic health determinants remains unchanged and unchallenged, and while Auckland’s infrastructure strains under a rapidly growing population, its burden of communicable disease will inevitably grow.



A New Model of Service Provision

Despite public and some health professional perceptions of the role of public health services being rooted in the "old public health" model, new service models have emerged, better able to tackle the challenges and complexities of the current and likely future health environment. The amalgamation in 1996 of three Auckland sub-regional public health services into a single regional entity has lead to many advantages. These include:

  • the opportunity to have a regional overview – communicable diseases do not respect District Health Board boundaries
  • greater co-ordination and consistency in analysis and response across the region
  • "critical mass", enabling specialisation within the public health team and a growth in expertise in certain core public health competencies  15   such as surveillance, environmental health and outbreak investigation
  • greater opportunity for innovation, more flexibility and responsiveness
  • the capacity to tackle projects and programmes external to HFA-funded or "traditional" public health service work.



Strengthening Communicable Disease Control

The current shape of policy and funding for and provision of public health services in New Zealand was set in June 1997 by the Ministry of Health with the publication of strategy document, "Strengthening Public Health Action".  16   This document envisaged public health action being strengthened through a concentration of efforts on the following four "themes":

  • focussing on the determinants of health
  • building strategic alliances
  • implementing comprehensive programmes
  • strengthening the public health infrastructure.

These themes provide a convenient framework to illustrate how Auckland Public Health has begun to move beyond the "old public health" model, with significant implications for the regional management of communicable diseases.


Focussing on the Determinants of Health
Any vision for achieving equitable health outcomes among population subgroups means tackling the proximal or "upstream" causes of ill health. In 1998, concerned about clustering of cases of TB and meningococcal disease, Auckland Public Health facilitated an "action research" project in Otara, in which representatives of community groups and agencies based in Otara were informed of the links between housing and health, and developed "local solutions" to address some of the issues they identified as of greatest relevance. These included a proposal for addressing overcrowding, through an accessory housing scheme. The publication of a report by the group  17   contributed to mounting pressure on the government from many groups to review housing policy, in particular, in relation to the most fundamental driver of overcrowding, housing affordability.  8  


Building Strategic Alliances
The occurrence of communicable diseases is intimately related to political, social, economic, environmental and institutional circumstances.(18) Along with other arenas of health improvement, communicable disease prevention and control must therefore be set within a context far wider than merely the health services. By definition, public health involves society acting collectively to improve and promote health and prevent disease.  19   Partnerships with community organisations, local and regional government, the media and the education, housing and social welfare sectors are essential to the success of any collective action to manage the impact of communicable diseases.

Intra-sector alliances have been strengthened over the past few years through collaboration with many different health sector organisations on a number of specific communicable disease-related projects. The 1998 Auckland Meningococcal Disease Awareness Programme lead by Auckland Public Health involved partnerships with a variety of Maori and Pacific Island health promotion and well-child providers.  20   These partnerships have rolled-over into other programmes facilitated by Auckland Public Health such as community-based TB control. A sense of collective responsibility for public health has been fostered by other partnerships, for example, with the food manufacturing industry in recent food safety awareness campaigns.


Implementing Comprehensive Programmes
Auckland Public Health’s involvement in the Hepatitis B Screening Programme has provided it with an opportunity to contribute substantially to the planning, implementation and evaluation of a comprehensive population-based disease management programme. Public and health professional awareness, recruitment, screening, surveillance, evaluation and treatment are all addressed through this programme.


Strengthening the Public Health Infrastructure
The public health infrastructure is far broader than just the public health services and includes all actors making a contribution to the health of society. In the context of this paper, however, the focus is on a regional public health service provider and its response to communicable disease challenges. We have chosen to focus on four critical infrastructural elements: public health legislation, surveillance, human resources and funding.

Public health legislation
The ability of public health services to respond to communicable disease threats may be empowered or constrained by the prevailing legislative environment. Public health officers are required and empowered by law to take action to prevent or control communicable diseases under various items of legislation such as the Health Act 1956, the Food Act 1981 and the Tuberculosis Act 1948.

The legal and social context in which many of these statutes were conceived has changed over time. A review of the Health Act and other related legislation has recently been promoted, with the aim of updating it and bringing it into line with other modern legislation, which is less prescriptive and gives greater emphasis on individual rights over public good. While a new Health Act would be welcome, for the opportunity to integrate various statutes and adopt a risk-based perspective, it represents a potential threat to the public health management of some communicable diseases of concern in Auckland. Should there be a move to limit Medical Officer of Health powers, such as those exercised under the Tuberculosis Act, for example, the opportunity to confine infective but unco-operative TB patients for treatment could well be jeopardised. During Auckland’s central business district (CBD) power crisis in 1998, public health officers exercised their statutory powers to close food premises and seize food for disposal where refrigeration was inadequate. As a result of this prompt action, no outbreaks of food-borne illness attributable to food outlets in the CBD occurred during or for several weeks after the crisis.  21  


Surveillance
Surveillance – the timely collation, analysis and dissemination of information on hazards, disease occurrence, and the impact of interventions – is a fundamental communicable disease control activity. Surveillance systems should provide prompt recognition and identification of changes in incidence of communicable diseases or of the occurrence of new emergent diseases. These systems depend for their effectiveness on the prompt notification of cases by physicians to the public health service. Under the Health Act, physicians are legally required to notify the public health service of any notifiable disease they suspect or diagnose. These data are collated on a database and used to guide local control measures.  22   However, under-notification is a problem.

The need for more effective communicable disease surveillance is increasing along with societal expectations for protection. Enhancements to the system to encourage notification have been instituted in Auckland over recent years. The simple measure of encouraging faxed notifications has been partially successful. Other solutions, such as electronic messaging, perhaps with associated financial incentives, are being considered.

Greater use of laboratory data is occurring, and is particularly important for diseases for which a laboratory test is always required for diagnosis. Improved connectivity with such databases, improved reference testing (eg, nucleic acid fingerprinting techniques for TB outbreaks), new analytic and communication tools (such as the use of geographic information systems in spatial analysis of outbreaks, and in public and health professional communications) are all enhancing this fundamental area of communicable disease control.

At the same time, the focus of surveillance is shifting from being driven by the availability of data towards an action-oriented model, which starts with identifying the users of surveillance reports and the outcomes they wish to achieve.  23   It may be at these levels that the most substantial gains in communicable disease prevention and control will be achieved.


Human resources
The public health workforce in Auckland is being strengthened through a variety of initiatives. One example is the development of a lay workforce to undertake community-based directly observed therapy (DOT) for TB patients. This is proving to be a more cost-effective and acceptable way of ensuring compliance with treatment than the previous system, which involved only public health nurses. Additional specialist staff have been employed to manage specific projects. Health Protection Officers are receiving more in-depth training in outbreak investigation and analysis.


Funding
For a number of years now a "ring fence" has protected the proportion of Vote: Health allocated to public health. Regional public health services receive funding through a contract from the Health Funding Authority (HFA). The contract is developed around a "provider plan", in which activities to be funded are negotiated annually. While these activities sit within the Ministry’s policy framework, there is scope for taking account of regional issues and priorities.

From time to time additional funding has been allocated for the management of large-scale epidemics, but for the most part outbreak investigations and control efforts must be conducted within existing budgets. Other funding sources such as research grants and sponsorship from industry have begun to be used for various initiatives outside the provider plan.

Nevertheless, what might be done as opposed to what can be done within budgetary and human resource constraints will always be a source of tension and difficult prioritisation decisions must be made. The Ministry of Health’s criteria for public health interventions outlined in "Strengthening Public Health Action" are useful to guide decision-making:

    • Does the health issue have a significant impact on current and future health status of the total population or of priority groups in terms of morbidity, mortality, quality of life, PYLL?
    • Are there effective means available to improve, promote or protect health or prevent disease?
    • If not, are there potential innovative means that could be evaluated?
    • Will the programme reduce health inequities?
    • Is the intervention likely to result in the best health gain for the resources applied?
    • Is there public support for tackling the issues?
    • Is the programme likely to be sustainable?

Not infrequently there is incomplete health outcome data, only limited evidence of effectiveness or lack of data on opportunity costs, with which to answer these questions with confidence. Many public health interventions, such as those conducted at community level, are unsuitable for a full experimental study with randomisation and blinding. They may rely for evidence instead on anecdote, expert opinion or the results of observational studies or uncontrolled experiments, all of which are subject to bias. This is perhaps less so in some arenas of communicable disease control (such as vaccination) compared with other spheres of public health intervention.

Nevertheless, there is a dearth of strong evidence to support some activities that have become accepted practice. The resource-intensive public health management of contacts of meningococcal disease illustrates this assertion. Chemoprophylaxis of contacts aims to prevent secondary cases but draws on a few uncontrolled, unblinded studies for its evidence base. Furthermore, there is lack of clarity about the definition of a "close" contact, and for how long after exposure to a case chemoprophylaxis of contacts should be recommended. These areas need further examination through well-designed research. However, the time and energy available to do this is limited because of increasing demands to attend to the "fire fighting" of investigation and control of outbreaks.

Communicable disease outbreak management is a core public health activity that illustrates some of the issues faced by a regional provider when prioritising its activities. Outbreak control is always a priority, overriding most other public health activities. One example of a communicable disease whose investigation and control requires the setting of explicit priorities is campylobacter infection. With over 2,000 cases notified annually in Auckland, the follow-up and investigation of sporadic cases is impossible, given the limited size of the public health workforce. Outbreaks of illness involving two or more people are given priority. This is because descriptive and analytical epidemiological techniques that are inappropriate to individual cases can be used to identify risk factors for infection and, in doing so, can allow control of hazards and the prevention of future illness.



Conclusions

Auckland’s burgeoning experience of new and re-emergent communicable diseases continues to test the public health service’s capacity to respond, at the same time testing the public’s confidence in control measures. The rapidly expanding diversity of ethnic, language and cultural groups and the growing population pose huge challenges to the effective communication of risks and benefits, and to the targeting, delivery and evaluation of communicable disease prevention and control interventions. Auckland Public Health’s "new" approach has enabled a start to be made on tackling the social and economic determinants of several key communicable diseases. Strategic partnerships are being fostered to support and implement comprehensive disease prevention and control programmes. The continued development of a strong infrastructure, including adequate resources, supportive legislation and robust surveillance systems, is vital if timely and effective public health action is to occur. Finally, well-designed research is required to ensure that programmes and activities are at once appropriate, cost-effective and acceptable to the public.



References

  1. Martin M, Mullard T, Calder L. High level of compliance with rifampicin chemoprophylaxis for meningococcal disease. NZ Public Health Report 1997;4:41–3
  2. Surveillance and control notes. NZ Public Health Report 1998;5:36
  3. Calder L. Tuberculosis increasing in young Aucklanders. Auckland Public Health Public Health Advice 2000;6:1–4
  4. Calder L, Hampton L, Prentice D, et al. A school and community outbreak of tuberculosis in Auckland. NZ Med J 2000;113:71–4
  5. Simmons G, Manning K. An outbreak of foodborne illness at an Auckland hui. NZ Public Health Report 1998;5:33–5
  6. Baker M. Rheumatic fever in New Zealand in the 1990s: still a cause for concern. NZ Public Health Report 1996;3:17-19
  7. Kay B. Review of New Zealand programme for exclusion and surveillance of exotic mosquitoes of public health significance. Report for the Ministry of Health. Wellington: Ministry of Health, 1997
  8. Business and Economic Research Ltd. Affordable housing in the Auckland region: issues, mechanisms and strategies. Report to Auckland Regional Council. Wellington: BERL, 1999
  9. Rainger W, Jones N, Jarman J, et al. Immunisation coverage and risk factors for immunisation failure in Auckland and Northland. NZ Public Health Report 1998;5:49–52
  10. Surveillance and control notes. NZ Public Health Report 1999;6:36–7
  11. Baker M, Eyles R, Bennet B et al. Emergence of verotoxigenic Escherichia coli (VTEC) in New Zealand. NZ Public Health Report 1999;6:9–12
  12. Dalton C, Douglas R. Great expectations: the coroners report on the South Australian haemolytic-uraemic syndrome outbreak. Med J Aust 1996;164:175–7
  13. Baker M, Eyles R, Bennett J, Nicol C, Wong W. Emergence of verotoxigenic Escherichia coli (VTEC) in New Zealand. New Zealand Public Health Report 1999;6:2
  14. P Hill, Public Health Medicine and Infectious Diseases Registrar, Auckland Healthcare, personal communication
  15. Stephenson P. Public health and disease prevention –moving forward in New Zealand and Australia: public health – nurturing infectious ideas. Healthcare Review – Online TM.3 (7); July 1999 http://www.enigma.co.nz/hcro/website/index.cfm?fuseaction=articledisplay&FeatureID=84
  16. Ministry of Health. Strengthening public health action: the strategic direction to improve, promote and protect the public health. Wellington: Ministry of Health, 1997
  17. Otara Housing and Health Local Solutions Group. Report to the National Health Committee. Auckland: Otara Housing and Health Local Solutions Group, 1998
  18. Alderslade R. The Public Health Act of 1848. BMJ 1998;317:549–50
  19. Committee of Inquiry into the Future of the Public Health in England. London: HMSO, Cmd 298, 1988
  20. Bullen C. Taking public health to the streets: the 1998 Auckland meningococcal disease awareness programme. Health Education and Behaviour (in press)
  21. Manning K. Health Impacts of the Auckland Power Crisis. J Aust Inst Env Health 1998;7:29–31
  22. Baker M, Roberts A. A new schedule of notifiable disease for New Zealand. NZ Public Health Report 1996;3:33–7
  23. N Jones, Public Health Medicine Specialist, Auckland Healthcare, personal communication

 
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