Measures to Prevent the Spread of Contagious Diseases by Air Transport

Jörg Siedenburg

Introduction

After a significant drop caused by the SARS-CoV-2 pandemic, air travel recovered and continues to be an important means for exchanging people and goods. More than 4 billion passengers are reported annually. However, contagious diseases can be spread by air traffic as well. Infected patients may use an aircraft and carry microbes to their destination or infect fellow passengers. Aircraft may carry unwanted passengers as well. Insect vectors as blind passengers may carry pathologic agents to the destinations of their vessels. The spread of Dengue Fever, Airport Malaria and Measles are examples.

Regulations on a national and international level, such as the International Health Regulations (IHR), have been implemented to prevent the spread of contagious diseases via international air traffic. The International Civil Aviation Organization (ICAO) has published guidelines for the disinsection of aircraft to preclude the carriage of arthropods.

Fig. 1: Schematic illustration of the ventilation of a large fuselage aircraft

AircraftsasaCarrierofInfectiousDiseases

At a cruising altitude of about 11.000 meters, the ambient pressure is about one-quarter compared to the sea level. A pressure cabin, using bleed air from the aircraft engine, creates a cabin pressure altitude of about 1.600 to 2.400 meters. The ensuing cabin pressure is about 25 % less than at sea level. Because outside air of less than -50 °C has to be heated to comfortable temperatures, the relative humidity of air is shallow. The subsequent physiological conditions on board (relative humidity between 5 and 15 %, 20–30 exchanges of cabin air, cleaning recirculation air with HEPA-(High-Efficiency Particulate Air) filters, laminar airflow in the cabin) make transmissions of infections very unlikely. The uniform forward orientation of passenger seats and little movement inside the cabin constitute more barriers to minimize the risk of transmission of contagious diseases within the aircraft cabin.

Nevertheless, air transport of infectious passengers is forbidden due to medical reasons, and IHR screening procedures prevent the boarding of contagious patients. Boarding, deboarding, and standing in line at check-in and baggage security controls pose a potential transmission hazard, which can be mitigated by additional measures like mouth-nose masks and face shields and keeping distance. During epidemics, often temperature screening before departure and/or after arrival can be implemented to identify infected passengers to deny boarding or isolating and observe them for a certain period to reduce the risk of importing a contagious disease.

During the ground time of scheduled flights, some arthropods may enter aircraft cabins, survive the flight time, and experience physiological conditions that are not arthropod-friendly. Assuming their remaining survival time matches the external incubation period of viruses or other parasites, it will be sufficient to recover from the stress of flight and have enough time to find susceptible humans at their destination to infect. It is very unlikely that all those pre-conditions are simultaneously suitable for a transmission match. Thus, a transmission is a rare event; however, given the many flights, such events happen regularly. There are a couple of reports of malaria transmission inside the aircraft or in the vicinity of airports where aircraft from malaria-endemic areas arrive. In addition, climate change and warmer temperatures in temperate climates make it easier for insects to thrive. Outbreaks of infectious diseases like Dengue Fever, Zika, West Nile Fever, etc., were formerly limited to tropical areas; therefore, the disinfection of aircraft before or during the flight is mandatory in certain countries for flights originating from tropical regions to minimize the risk of exporting them.

Fig. 2: At airports in the tropics not only passengers are boarding, insect vectors may enter as “blind passengers.

Disinsection of Aircraft

D-Phenothrin and Permethrin are used to disinsect aircraft. Both are so-called pyrethroids. Pyrethrum, a natural product from chrysanthemum flowers, was one of the first insecticides. Permethrin has a residual effect primarily on surfaces, affecting insects resting on those surfaces. d-Phenothrin has a small residual effect as well but acts primarily with significant “knockdown“ and “killing” effects on insects. Different methods certified by the ICAO (International Civil Aviation Organization) are recommended. A residual treatment method must be applied every eight weeks. Since 2023, three alternatives have been used.

• The pre-embarkation method is applied after cleaning the aircraft and catering, and after the cleaned surfaces have dried, 2 % d-Phenothrin as a fast-acting “knock-down”-insecticide is applied (35 g/100 m³).
• For the pre-departure method, d-Phenothrin in the same concentration is applied after cleaning and catering with the passengers seated and the overhead lockers still open.
• The on-arrival method is a contingency method and will be applied if the authorities at the destination are unsatisfied with the previous disinsection. It is applied before opening the doors of the aircraft.

Many airlines still use the so-called top-of-descent method or in-flight spraying (figure 3). D-Phenothrin is used as well. In each aisle a flight attendant has to walk slowly down the aisle and spray from two containers. The empty containers must be delivered to the health authorities. A standard announcement must announce each disinsection. The previous disinsection must be documented, and entry into the Declaration of Health must be mandatory.

Fig. 3: Top of descent disinsection with d-Phenothrin applied by the flight attendant from two bottles

Nevertheless, although all the different methods described minimize transmission of contagious diseases, the risk can never be reduced to zero. If clusters of exotic infections are found, quick diagnosis, thorough history, and measures to contain an initially small outbreak are required on a general level. A quick diagnosis can save the lives of those infected personally and potentially contact persons on a general level.

TransportofContagiousPatients

Air transport of contagious patients remains a big problem. When isolating a patient, who needs medical care, closed and open isolation are possible. In closed isolation, the patient is lying inside a container, and there is limited access for physicians and nurses from outside. Only minimal procedures can be performed. In open isolation, patients, doctors, and nurses are inside the same container, and complex procedures and logistics are possible. Both methods have been realized in air transport, using hypobaric pressure inside the containers. The latter prevents viral contamination from inside to outside. Small containers a little bit bigger than litter have been used in the French Forces for years. IsoArk^® and EpiShuttle^® are commercial solutions. However, these methods suit contagious diseases, not highly contagious diseases like hemorrhagic fevers.

Fig. 4: EpiShuttle^® Isoltionstrage an Bord einer Pilatus P24 (Bild: Pilatus Aircraft Ltd, Schweiz)

The problem is a loss of cabin pressure. This is a rare event which might have catastrophic consequences for the transport of contagious patients. An aircraft leak would result in a sudden drop in cabin pressure; the container would explode. Viruses would spread in the form of aerosols and contaminate all persons on board and a vast area at a potential crash site. Therefore, countermeasures in case of a loss of cabin pressure are required to mitigate the risk. In 2014, an A 340 aircraft, the “Robert Koch,” was equipped accordingly for transporting German soldiers assisting in the Ebola virus outbreak in West Africa. It consisted of a tent-like container for patient and treatment, another one for doffing (get out of personal protection equipment [PPE]), and for donning (get into PPE) and stocks. All three were inter-connected and connected with an emergency pressure equilibration, basically a big plastic sack that would hold several hundred cubic meters of air in case of a loss of cabin pressure. The aircraft had never been used and was dismantled the following year. Should the need arise again, a copy of this make-shift model could not be repeated because many standards for aircraft construction, which also apply to equipment, would not allow for a simple copy.

Another aircraft used for transporting highly contagious patients was created under the aegis of the US CDC in the aftermath of the SARS epidemic in 2006. No construction details are published. Whether a loss of cabin pressure is being catered for is not clear.

In 2019, a project for a pan-European solution had been planned. The German Ministry of Foreign Affairs, Lufthansa Technik, Charité University Hospital in Berlin, and the EU were partners. It was based on a container solution consisting of three standard metal containers fitting to big transport aircraft and connected to a big plastic sack for pressure equilibration. These would have been stored in Berlin and fitted to any by any EU member. However, after significant planning and work had been done, the project was stopped for some reason.

For now, there would be no way to repatriate a highly contagious patient from overseas to Germany or any other European state. Another problem that would have to be addressed is that—different from scheduled air transport—state aircraft like the one we discuss would need a special permit to use the air space of all the countries overflown. The responses of several national aviation authorities to a request for air transportation of a patient with hemorrhagic fever can only be speculative.

References

1. Siedenburg J: Luftverkehr und kontagiöse Erkrankungen. In: Siedenburg J, Küpper T (Hrsg.): Moderne Flugmedizin. Gentner-Verlag, Stuttgart 2015.
2. Siedenburg J: Update kontagiöse Erkrankungen und internationaler Flugverkehr. FuR 2020; 27(3): 130–135. mehr lesen
3. WHO (2023): WHO aircraft disinsection methods and procedures. , last access October 10, 2024. mehr lesen

Author

Captain (Navy MC Res) Dr. med. Jörg Siedenburg
Regional Medical Officer
German Embassy Nairobi
Kurstraße 36, 10117 Berlin
E-Mail: arzt-1@nair.auswaertiges-amt.de

Ethics in Military Medicine in a Changing Global Environment

Joachim Hoitz

Introduction

The key question is how to make ethical decisions as a military healthcare servicemember. The background against which decisions in military health ethics must be made is a rapidly changing global environment. Contextual conditions in our current international situation, knowledge of the fundamental ethical theories, and modern general approaches to healthcare ethics form the background in front of which military healthcare professionals act. Acting at the intersection between healthcare ethics and military ethics, knowledge of basic ethical theories and general approaches to healthcare ethics as well as of “jus in bello”, laws of military conflict, and military virtues is mandatory for them. Although they have a joint base, there are several topics that are prone to dispute between military healthcare and troop professionals. An important topic is triage as an allocation problem. Quick decision guidelines in algorithms are available for traumatic mass casualties; however, they are missing in infectiology. Everything brought together (Figure 1) is a firm frame for discussing how to apply military healthcare ethics. Knowledge and training are crucial.

Fig. 1: A firm frame of discussing how to apply military healthcare ethics

Context Conditions

Military conflicts

Currently, there are numerous military conflicts. From a Western perspective, the Russian war against Ukraine and the military actions in the Middle East in the Gaza Strip and in Israel after the Hamas assault on Israel in Oct 2023, the conflict with the Hisbollah with the potential to involve also Lebanon and Iran as well, are the most prominent. A situation like a new “Cold War” between NATO and Russia began. Additionally, there has been a general decline in democratic governments and a tendency toward autocratic governments worldwide. Soon, we must expect unpredictable reactions from the BRICS-States, especially China and Russia, to the results of the upcoming US presidential election, whoever will win. Hence, an increased risk of violence and military conflicts can be regarded as the first contextcondition.

Migration

We have faced sustained migration to Europe and Northern America for several years. Migrating people are refugees from regional military conflicts or autocratic governments or for economic reasons. In Western states, increased social diversity creates social tensions and promotes populist movements. This development can be regarded as a second context condition.

Global warming

Global warming is undoubtedly a third context condition. Increasing temperatures result in more frequent extreme weather events like droughts, hurricanes, heavy rainstorms, and flooding. Rising sea levels and increased desertification, as long-lasting results of global climate change, will boost additional migration of affected inhabitants and aggravate the migration pressure.

Infectious diseases

A fourth context condition is the infectious disease situation. With the COVID-19 pandemic just over, we are afraid of a next epidemic or pandemic. It may be caused by Influenza H5N1, which is closely monitored around the world, by e.g., Nipah virus, highly contagious pathogens, or even unknown viruses. At the same time, we face multiple resistant germs arising as selections of well-known species.

The whole context

Summarizing, we currently live in a rapidly changing world, with an increased risk of military conflicts in combination with high social and cross-cultural tensions in an environment of climate changes and global warming promoting increased spread of well-known or new infectious diseases resulting in highly complex regional and global situations to be judged as potentially precarious. These context conditions shape the scenery in front of which military healthcare professionals will act and make ethical decisions.

Basic Ethical Theories

Three major ethical theory systems have been developed over the centuries, each with a different focus. For military healthcare professionals, considering each of these basic ethical theories is mandatory in decision-making.

Virtue ethics

From the antique world, the oldest of these three ethical paradigms, the “virtue ethics” or “ethics of being a man of virtue”, was developed by Aristotle (384–322 B.C.) in the “Nichomachean Ethics”: “Virtue is a rational activity of the soul.” “Virtue is a disposition to do the right thing in a concrete real-life situation and to do it for the right reasons, in the right way, and as a result of a well-developed character trait.” The theory focuses on the actor of an act and his soul (conscience, intention). Corine Pelluchon (*1967) can be regarded as a modern virtue philosopher.

Deontology

“Deontology” or “Duty Ethics” was the result of thinking on moral topics of Immanuel Kant (1742–1804). In his book “Grounding for the Metaphysics of Morals”, he mentioned the famous “Categorial Imperative” for the first time: “Act only according to that maxim whereby you can at the same time will that it should become a universal law” “So act that you treat humanity, whether in your person or the person of any other, always at the same time as an end, never merely as a means”. The theory focuses on the act only, regardless of consequences. Tom Scanlon (*1940) can be regarded as a modern deontologist.

Consequentialism

“Consequentialism” and its famous derivative “Utilitarianism” have been developed be Jeremy Bentham (1748–1832) and John Stewart Mill (1806–1873). “The ultimate good is always the greatest happiness of the greatest number of sentient beings, whereby everyone, including the moral agent, counts for one unit and no one counts for more than one”. This theory focuses on the consequences of an act and the objective of the best outcome overall. Peter Singer (*1946) can be regarded as a modern consequentialist.

General Approaches to Healthcare Ethics

After centuries of paternalism with the primacy of the physician knowing best for the patient and deciding what to do, the patient´s self-determination has taken over the primacy in healthcare ethics.

4-Principles

The 4 principles, developed by Tom L. Beauchamp and James F. Childress in the book “Principles of Biomedical Ethics” in 1979, are the primary approach to healthcare ethics in current Western societies. They consist of:

• Autonomy: the right of competent adults to determine their treatment
• Beneficence: favorable outcome for the patient
• Non-Maleficence: do not harm
• Justice: fairness on the basis of equality and non-discrimination

Application of these 4 principles is mainly regarded as the ethical standard in modern healthcare ethics. However, these 4 principles have been challenged by two other approaches

Casuistry

The idea of casuistry, stated by Albert Jonsen and Stephen Toulmin in their book “The Abuse of Casuistry. A History of Moral Reasoning” in 1988, approaches to healthcare ethics differently. They promote relying on case studies, focusing on the analysis of individual cases, and deriving moral principles and decisions out of these individual cases by interpreting and applying ethical rules individually. They find it the wrong way to rely on abstract principles or theories to be purely applied to a precise case.

Care ethics

Caroll Gilligan´s “In a Different Voice” 1982 and Nel Noddings “Caring. A Feminine Approach to Ethics & Moral Education” 1984 developed a different perspective to healthcare ethics. They stress the necessity to consider relationships and context, to show empathy and compassion, and to show responsibility and respect dependency applied as practical and situational approaches. It was thought of as a critique of traditional theories in healthcare ethics.

Military Ethics

As a military servicemember, military healthcare professionals must also be aware of military ethics. “Jus in Bello” follows the international Humanitarian Law (IHL), especially the “Geneva Conventions and Associated Protocols.” Laws of armed conflict regulate, e.g., the discrimination between combatants and non-combatants, stress the proportionality of military reactions, and force to think about the necessity of military force application. Military virtues such as courage, integrity, loyalty, discipline, responsibility, and accountability must be respected.

Fig. 2: The author´s reiterative cycle model to prepare for deployment

Military Healthcare Ethics

Military healthcare professionals act at the intersection of medical and military ethics. Military framework and medical framework share the IHL, esp. Geneva Convention. However, in the military framework are national laws and the military justice system, and in the medical framework are the principles of healthcare ethics and national healthcare professional regulatory bodies for ethical practice to be respected. This may result in some topics of military healthcare ethics prone to dispute, e.g., the use of weapons by military healthcare personnel, caring for civilians during military operations, and participation of physicians in torture. Another topic is using protective emblems like “Red Cross and Red Crescent”. There is always the risk of not being protected but being targets for attacks, as the current experience of Russia´s disrespect of the Red Cross in the Ukrainian-Russia conflict underlines. Another additional topic is the dual loyalty dispute, e.g., balancing the humanitarian need to care for civilian casualties from conflict and the military need for empty beds in military treatment facilities for servicemembers. Or the question of whether, in doubt, a successful military mission has primacy over international humanitarian law. There are published standard guidelines of the World Medical Association (WMA), International Committee of Military Medicine (ICMM), International Committee of the Red Cross (ICRC), and other associations: “Ethical Principles of Healthcare in Times of Armed Conflict and Other Emergencies” as a standard to be followed [5].

Triage

One ethical topic in military healthcare is the necessity of triage in mass casualties, an allocation problem with a mismatch between resources and needs in time-critical situations. NATO has defined 5 treatment groups: T1 red -> immediate treatment, T2 yellow →urgent treatment, T3 green → minimal treatment, T4 blue → expectant treatment, and T5 black → dead. In situations with traumatological mass casualties, there are simple triage systems available to assign the patients to the treatment group. For example, there are only seven questions to be answered in the mSTaRT -schema (modified Simple Triage and Rapid Treatment) as a decision guidance for assigning the casualty to the triage group [2]. However, no triage system is available in situations with mass casualties in infectious diseases. What questions to ask for a similar triage system in infectiology should be discussed as decision guidance. The “next level of the game” to be imagined is a combination of traumatological mass casualties during a pandemic or highly contagious diseases. There is a civilian report on this topic of a university hospital in Beirut experiencing a huge explosion on August 4, 2020, during the Covid-19 pandemic, destroying parts of the hospital [3]. In the military scenario, imagine a military attack during a pandemic, e.g., in World War I during the Spanish Flu. It is crucial to discuss how to prepare for those scenarios.

Fig. 3: Screenshot of the app “Military Healthcare Ethics”, free of charge downloadable from Google Play or Apple Store

How to Apply Military Healthcare Ethics

To begin with the bad news, ethics is no problem solver by itself:

„Philosophical ethics is a primarily theoretical project. It´s focus is not on solving precise moral issues, but rather on interpreting, discussing and revising ethical criteria.“(Translation by author).

However, it may be a facilitator of understanding context and interdependencies, preparing better decision-making:

„The theory primarily serves to clarify propositions about which we do not have a firm opinion and to discover interdependencies that we cannot understand without theoretical support. “(Translation by author) [4].

In my preparation as an anesthesiologist for my own deployments on missions during active duty times, I followed a reiterative cycle model, “Be prepared,” hoping that prevention of astonishment will prevent moral injury (figure 2).

Recently, an outstanding helpful article was published, “King´s Military Healthcare Ethics Analytical Framework 2024” [1]. Following 4 steps:

1. Identify the problem,
2. Analyse,
3. Fuse,
4. Decide,

you will be guided through an individual decision process also respecting the four perspectives of “patient,” “clinical,” “legal,” and “societal/military.” Training and repeated engagement topics of military healthcare ethics are crucial for enabling military healthcare professionals to make good decisions and prevent moral injury. Courses at the “ICMM Center of Reference for Education on IHL and ethics” in Zurich, Switzerland, are recommended, as well as the application for smartphones, “Military Healthcare Ethics from King´s College London”, free of charge and available at the corresponding application stores (figure 3).

Making ethical decisions for military healthcare professionals will always be challenging. However, knowledge and training may relieve stress and prevent moral injury.

References

1. Beardmore CE, Bricknell MC, Kelly J, Lough F: Commentary - A Military Healthcare Ethics Framework, Military Medicine, 2024;, usae351. . (last accessed Sept 15, 2024). mehr lesen
2. Kanz KG, Hornburger P, Kai M, et al: mSTaRT-Algorithmus für Sichtung, Behandlung und Transport bei einem Massenanfall von Verletzten. Notfall Rettungsmedizin 2006; 9(3): 264-270. mehr lesen
3. Mitri M, Fadel FA, Juvelekian G: Resilience in Healthcare. Surviving a Coinciding Pandemic, a Major Deadly Disaster, and a Economic Collapse. What Did we learn? Chest 2021; 160(5): 1986-1988. mehr lesen
4. Nida-Rümelin J: Theoretische und angewandte Ethik: Paradigmen, Begründungen, Bereiche, In: Nida-Rümelin, J (Hrsg): Angewandte Ethik. Die Bereichsethiken und ihre theoretische Fundierung, Kröner, Stuttgart 1996, S. 2-85.
5. World Medical Association: Ethical Principles of Healthcare in Times of Armed Conflict and Other Emergencies. (last accessed Sept 15, 2024). mehr lesen

Remark

Invited keynote speech at the 4th Symposium on Tropical Medicine and Infectious Diseases in an International Military Context.

Author

Brigadier General (MC RET.) Dr. Joachim Hoitz
Duvenstedter Triftweg 15, 22397 Hamburg
E-Mail: jhoitz@web.de