Post-"911" discussion about preparing, as a society, for biological and chemical terrorism or infectious diseases like SARS suggests similarities in potential public health impacts of such threats. As a hypothesis for focusing debate, we propose that a system of healthcare including house calls might be a good strategy for reducing the impact of both biological/chemical terrorism and highly infectious diseases. We present some ideas and very simplified calculations to argue that a different approach to preliminary assessment, triage and treatment is feasible, and could reduce risks to public health and security by reducing the movement of people who may spread infection or toxins while threats are assessed.

Motivations

Over the last 30-50 years, the practice of house calls by physicians or other healthcare workers has mostly disappeared. Increasingly, patients who believe they are unwell present at physicians' offices, walk-in clinics or hospital emergency wards. This leads to a problem in the case of an infectious disease outbreak or of a terrorism incident involving a toxic agent that can be transported on an infected individual's clothing or person. In such a case, it is not in the best public interest that affected individuals mingle with others in public places, especially doctors' offices, clinics and hospitals where healthcare workers may be implicated. On the other hand, to minimize the spread of the illness it is imperative that patients be assessed and diagnosed rapidly and receive prompt medical attention. In the case of terrorism involving a toxic agent, rapid environmental cleanup is also required.

Over the same period, that is, post-World War II, the number of deaths due to infectious diseases in the developed world has become very small. The Australian Bureau of Statistics (2002), in particular, prefaces its report "Australian Social Trends 1997 - Health - Mortality & Morbidity: Infectious Diseases" with the sub-headline "Between 1921 and 1995, death rates from infectious diseases fell from 185 to 6 per 100,000 population." We believe that, due to this remarkable decline, we have very little mental preparedness for dealing with an old-fashioned epidemic involving a disease with high morbidity. Even though significant numbers of people die each year of influenza, they are generally already frail (US Centers for Disease Control 1995).

There are many reasons to expect that this happy absence of infectious diseases and accidental or deliberate large-scale injury will not continue. A search of The Lancet (2004-4-26 at 22:55) found 9,159 hits using the keywords "drug resistant infection." SARS has re-emerged in Beijing, a large-scale cull of poultry has been undertaken in British Columbia (see also The Lancet 2004) and anti-mosquito measures have been applied in an attempt to control West Nile infection in various parts of North America (Sharp 2003).

New pathogens emerge over time (https://www.globalhealth.org/view_top.php3?id=229; Weissenböck et al. 2002) and deaths due to infectious diseases appear to be increasing (Pinner et al. 1996; Pindera 2004).

We believe it to be self-evident that the use of health visits (house calls) by workers trained in infection and toxin control as the first-contact of patients with the healthcare infrastructure would go a long way to reducing the risks posed above. The more important question is whether it is feasible and reasonable, and the rest of our viewpoint article considers this issue.

Elements of a Solution

To provide prompt diagnosis and care while minimizing social contacts of infected patients, it would be ideal if the medical care could come to the patient. Implementation would require a group of healthcare workers who are well-trained in infection control, triage, testing and sample-gathering. Such a group of workers could provide initial care, decide which patients may safely go to a public facility, and gather samples to screen for known or unknown pathogens.  

The gathering and analysis of patient samples, a particularly important element in dealing with infectious outbreaks and biological/chemical terrorism, at the moment generally takes place on a per-patient basis, which is both too expensive and too slow to adequately cope with a situation requiring extensive testing of a relatively large population. We propose an alternative based on some fundamental changes.

First, the collection of these samples could be greatly enhanced by making effective use of modern communication technology to manage the process. Internet and telephone connectivity are common enough that patient screening could be organized remotely. Already programs such as the Ontario Telehealth initiative (London Free Press2003; Jennett et al. 2004) are beginning to use connectivity as a tool for providing healthcare advice. Combining communications and well-constructed Web-based information systems with appropriate teams of mobile health visitors supported, managed and advised by physicians, public-health specialists and technical workers could facilitate more efficient and more reliable identification of emerging risks. Even better would be the use of sensors such as thermometers, imaging devices or other measurement technology connected to the communications tools.  

Second, we believe that many patients, using telecommunications support, could collect their own samples and/or measurements for screening purposes if appropriate kits were developed, standardized and provided as items that should be in every medicine cabinet.

Third, the testing process itself could be streamlined by carefully pooling multiple samples to screen for particular pathogens, especially rare or novel ones. This could be used to eliminate large groups of subjects from further investigation along particular directions, while permitting a return to individual samples whenever necessary. Moreover, it seems likely that an infrastructure favouring mobile workers needing rapid answers for tests would encourage the development of inexpensive and portable tools for the purpose, including ways to split and pool samples efficiently.

Obstacles to a House-Calls Model

The primary obstacle to implementing any new service delivery system is posed by the mass of investment, structure and habit built into any existing system. We do not propose to address "management of change" issues here, in part because it will be a factor in whatever new systems are implemented. Rather, we consider whether a new system of the type described will be markedly different in costs from the existing system. This ignores the catastrophic cost of a failure of an "office/hospital" system that is compromised by infectious disease or by terrorist attack.

Two financial obstacles to people both seeking medical advice and staying home when they are sick are co-payment fees and wage loss. To control health insurance costs, either public or private, there have been many suggestions that patients should contribute to the fees for physician consultations by co-payments, of which but one example is the scheme introduced recently in Germany (Deutsche Welle 2003; Orellana 2004). Co-payments are intended to be a disincentive to seeing a physician and may result in individuals electing not to seek medical help when, in fact, they should. A second disincentive is the income loss incurred when a person is unable to work. This was arguably the most difficult obstacle to "voluntary" quarantine in the Toronto SARS outbreak (London Free Press 2003). Appropriate minimization of these obstacles would add to the costs of any "house-calls" system, but should increase its effectiveness in containing an outbreak of an infectious disease or the impact of an attack by toxic or infectious substances. Effective quarantine is, of course, required for any system that is established.

Practicalities

We believe that the task of implementing a "house-calls" system need be no more complex or costly than many other public health ventures. While the administrative overhead involved in managing and supervising the body of house-call workers would undoubtedly be substantial, current structures already involve a small army of support staff to operate. Presently laboratory tests identify pathogens in an individual. By contrast, the main benefits of testing for dangerous pathogens accrue to the members of society who do NOT get infected. In jurisdictions where the patient pays part of the laboratory costs, they are subsidizing the public good. The same issue, of course, is a difficulty for immunization schemes, where even if there are no charges, those participating take the risk of side effects while those who do not get the benefit of the herd effect. Even where tests are publicly funded, we believe individualized tests to be inefficient.

Under our proposal, physicians and other healthcare workers would have somewhat different daily work patterns than in the present "doctor's office" approach. The mechanisms by which remuneration is organized may also need to be different from the current schedule of fees approach. However, we already have models for this in public health and in emergency care, of which our proposal may be considered an outreach. Indeed, there are parallels with the air-rescue system used by the American military in Vietnam (Nathens et al. 2004), where physicians at central locations advised helicopter-borne paramedical staff. In part, this system was used because physicians were considered too valuable to put in harm's way, but also because there were not enough of them to staff all the medevac helicopters.

In a simplified calculation using a range of the annual number of events per patient from 0.25 to 10, a range of patients per day per worker from 5 to 40, a cost per worker (including all overhead) of $75,000 to $250,000, and based on 200 working days per year, the annual cost of workers per person in the population in this system varies from $2.50 to $2,500. Even though the true cost is likely to be closer to the higher end of this range, this is not dissimilar to sums already being spent. In other contexts, studies have found that house calls can be cost-effective (Barclay 2003).

Conclusion

Our numbers and our examples are not meant for planning. Rather, they are intended to argue that an infectious-disease/toxic-substance-attack management system of the style described is within the bounds of possibility, especially if there is an active effort to enhance its efficiency with good management and technical support. It would, of course, change many aspects of healthcare outside the scope of infection or toxins, and overlap into non-public health aspects of the healthcare infrastructure. Our contention is that initiatives like those presented above deserve vigorous discussion and debate, despite the political reluctance or even antipathy in many nations toward "free" healthcare services. In our new climate of drug-resistant disease, together with the threat of bioterrorism, the alternative may turn out to be a "free" death for many of our nation's citizens.

We welcome comment and hope that our ideas will encourage further investigation of novel approaches to the challenge of first-line medical care.

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