Where is the Greatest Risk of Infectious Disease Transmission While Onboard an Airplane?

Where is the Greatest Risk of Infectious Disease Transmission While Onboard an Airplane?

Patient Presentation
A 4-month-old female came to clinic for a health supervision visit. She was a former full-term infant with no problems pre- or post-natally. The family was leaving in 2 weeks to visit relatives in Africa for 6 weeks, and asked about precautions they should take during the flight. The parents were fully immunized except for seasonal influenza, and had not discussed their own health needs with their own physician.

The pertinent physical exam showed a smiling infant with weight and length parameters at the 25% and head circumference at the 50%.
Her examination was normal. The diagnosis of a healthy female was made. After reviewing the country specific vaccine recommendations from the Centers for Disease Control, the pediatrician recommended that the parents talk with their own physician about malaria prophylaxis and yellow fever vaccine. She also recommended that they receive seasonal influenza that could be given at the influenza clinic adjacent to the pediatric clinic after the visit. “There’s not much more you can do while on the airplane other than use the hand sanitizers a lot and turn on the overhead vent to circulate the air,” the pediatrician counseled. “Especially try to make sure you wash your hands before touching the baby,” he counseled. He also discussed other travel recommendations for clean water use and mosquito control while in the country. “Because of her age, if she gets sick we recommend she sees a doctor,” he advised them.

Discussion
Airplanes are a global transportation mechanism for the world for passengers and cargo. They are an engine which helps to fuel the global economy. In 2014, over 3.3 billion people traveled to more than 41,000 airports and 50,000 routes across the world. It is possible to travel around the world within about 24 hours. This is shorter than most infectious disease incubation periods. Although entry screening into countries is done, exit screening closer to the source is a better model as noted with the recent Ebola outbreak in west Africa in 2014.

Individual infectious disease risk includes the generation rate of the infectious disease, i.e. the source strength, the proximity and duration of the exposure, ventilation, and chance. Most commercial aircraft have cabin airflow that is designed to change over 10-15x/hour or more, with internal filtered and recirculated air progressively becoming diluted with incoming external air. The ventilation is designed to flow from side-to-side of the aircraft and not down the long axis of the fuselage. High efficiency particulate arrestance (HEPA) air filters are used which can capture up to 99.97% of 0.1-0.3 micrometer particulate and 100% of larger particles. HEPA filters are not required nor regulated in the US and Europe. The environmental control system is also designed to mitigate external contaminants into the cabin though.

Infectious diseases can be transmitted by airborne particulates, large droplets which settle on surfaces (60% alcohol) if not visibly dirty or if soap and water are not available. Using sanitzer wipes of surfaces around food may also be helpful. Minimizing exposures by keeping the air conditioning nozzle on at a low setting, not sitting in the window seat during the winter season and sitting near the front of the aircraft can help. People traveling should be current with routine vaccination including country specific diseases. Travel clinic or a knowledgeable physicians office with enough time to finish before traveling is important. Usually this is 4 to 6 weeks before traveling. Some travel clinics may not provide Pediatric local pediatrician. Mask wearing in-flight has also been shown to decrease the acquisition but is often not practical especially on long flights.

Learning Point
The overall risk of infectious diseases being spread on board during airline travel is small but does occur. According to Mangili, Vindes and Gendreau in 2015: “Current risk assessment protocols used by public health authorities for inflight infectious disease exposures are typically based upon the proximity of the fellow passenger to the index passenger, sitting within two rows of the index passenger and the duration of the exposure, exemplified by studies of transmission of Mycobacterium tuberculosis on board and air flight which is limited to close contacts and a flight time of greater than eight hours. This protocol is based upon experiences with previous tuberculous exposures/outbreaks aboard commercial flights and has become conventional wisdom for investigating most aircraft related infectious disease and incidences.” These authors note that this protocol does not consider ventilation, an infectious disease key modifier, and there are other mathematical formulas which might be more accurate.

Questions for Further Discussion
1. What infectious diseases are potentially spread by air travel?
2. What routine travel instructions do you provide to families?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Traveler’s Health

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Pavia AT. Germs on a plane: aircraft, international travel, and the global spread of disease. J Infect Dis. 2007 Mar 1;195(5):621-2.
European Centre for Disease Prevention and Control. Risk assessment guidelines for infectious diseases transmitted on aircraft. Available from the Internet at http://ecdc.europa.eu/en/publications/Publications/0906_TER_Risk_Assessment_Guidelines_for_Infectious_Diseases_Transmitted_on_Aircraft.pdf (2009, cited 1/17/17).

Bogoch II, Creatore MI, Cetron MS, et.al.. Assessment of the potential for international dissemination of Ebola virus via commercial air travel during the 2014 west African outbreak. Lancet. 2015 Jan 3;385(9962):29-35.

Centers for Disease Control. Conveyance and Transportation Issues: Air Travel. Yellow Book. Available from the Internet at https://wwwnc.cdc.gov/travel/yellowbook/2016/conveyance-transportation-issues/air-travel (rev. 7/10/15, cited 1/17/17).

Mangili A, Vindenes T, Gendreau M. Infectious Risks of Air Travel. Microbiol Spectr. 2015 Oct;3(5).

World Health Organization. Transmission of communicable diseases on aircraft. Available from the Internet at http://www.who.int/ith/mode_of_travel/tcd_aircraft/en/ (cited 1/17/17).

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital

Date
March 20, 2017

Question and Answer

The highest risk of an infectious disease transmission on board an aircraft is within how many rows of an index case?

A. 0, same row as passenger
B. 1 row
C. 2 rows
D. 4 rows
E. 6 rows

Answer: C

The overall risk of infectious diseases being spread on board during airline travel is small but does occur.
According to Mangili, Vindes and Gendreau in 2015:
Current risk assessment protocols used by public health authorities for inflight infectious disease exposures are typically based upon the proximity of the fellow passenger to the index passenger, sitting within two rows of the index passenger and the duration of the exposure, exemplified by studies of transmission of Mycobacterium tuberculosis on board and air flight which is limited to close contacts and a flight time of greater than eight hours. This protocol is based upon experiences with previous tuberculous exposures/outbreaks aboard commercial flights and has become conventional wisdom for investigating most aircraft related infectious disease and incidences.”
These authors note that this protocol does not consider ventilation, an infectious disease key modifier, and there are other mathematical formulas which might be more accurate.

To review the entire case, see Where is the Greatest Risk of Infectious Disease Transmission While Onboard an Airplane?

CME Credit?


Courtesy of: public domain no attribution necessary

Spring Break

PediatricEducation.org is taking a short Spring break. The next case will be published on March 20. In the meantime, please take a look at the different Archives and Curriculum Maps listed at the top of the page.

We appreciate your patronage,
Donna D’Alessandro and Michael D’Alessandro, curators.

What Health Risks Does Climate Change Pose?

Patient Presentation
A 9-month-old male came to clinic for his health supervision visit. His parents were graduate students at the local university and would be returning to live in China in 2 weeks. They were wondering about vaccines particularly for Japanese encephalitis because they would be living in a high risk area in China. The past medical history was unremarkable. The pertinent physical exam showed normal vital signs with growth parameters between 10-25% for height and weight and 50% for head circumference. The examination was otherwise unremarkable.

The diagnosis of a healthy male was made. The pediatrician discussed the options of starting the Japanese encephalitis vaccine in the U.S. and finishing it in China or waiting until they went to China to do the complete series there. “Japanese Encephalitis virus is more common during the warmer months, but I don’t know with the extent of climate change, if the risky time period has been extended,” the pediatrician said. Reviewing some governmental information with the parents on the computer in the room, the pediatrician was able to find out that there had been extension of the risk areas and time periods in East Asia. As it was April and the risk would be increasing, and after more discussion, the family decided to do the first Japanese Encephalitis vaccine in the U.S. and then followup with the second one once they were in China. The family felt good as this was similar to the routine Chinese vaccine schedule for infants also.

Discussion
Japanese encephalitis virus (JEV) is a Flavivirae, arbovirus that is endemic to many areas of Asia and the Pacific. It is estimated to affect ~70,000 people/year with ~10-15,000 deaths yearly in 20 countries, with a fatality rate of 35-40%. It can cause encephalitis and irreversible neurological morbidity. JEV is spread by Culex mosquitos which feed on swine. Increased environmental temperature and increased humidity (warm air is more moist) increases mosquito numbers, their survivability and ultimate dissemination. China has the highest rates of JEV with particular areas being more prone, as some areas co-farm rice and swine and the families live closely to the rice paddies and livestock which encourages transmission. JEV’s range has expanded over the past few decades including in 2009 into Tibet which was thought to be immune because of its altitude. Similar geographic spread has been found in other countries too such as Australia. Mass immunization in China and other countries has decreased the disease but it still remains a threat.

Learning Point
Weather is a moment-to-moment, day-to-day event and differs from climate which occurs across seasons, many years, and regions. “Climatic conditions and weather patterns have many consequences for human physiology, health and survival. Some health impacts, as from extreme exposures such as heat waves, occur directly. However, most climate-related health risks are mediated via the influences of climatic changes and shorter term weather fluctuations on food yields, water flows, patterns of infectious disease and the movement or displacement of groups and populations. When climatic conditions change over time, then we should expect changes in patterns of health risks and in population health profiles.” Most climatic health issues are not due to direct affects, but are due to indirect effects on the environment, ecology and social impacts.

Climate change health conditions include:

  • Primary/direct health effects
    • Are from extreme events such as heat waves, floods, fires, hurricanes/typhoons, landslides, tornados, and storms. The intensity and frequency of these events obviously can affect more people more frequently.
    • Direct health impact includes injuries, hospitalizations, poisoning, death, and numerous mental health issues. Children are especially affected by mental health issues.
  • Secondary health effects
    • Air quality related problems such as allergies and asthma
      • Air pollutants (including ground level ozone changes) and aeroallergens can increase because of wildfires, rising temperatures, rainfall patterns and altered crop yields.
    • Food related problems which can affect food supply, quality and overall nutrition
      • Rainfall patterns and soil temperature affects crop and animal food yields
      • Increased contamination of food/water with bacteria or environmental pollutants (including sewage) making food/water unusable
    • Infectious disease patterns
      • Expansion of number, range and activity of host species or vector species increases the infectious disease risks
      • Examples include non-human hosts of rodents, bats and vector-born illnesses such as Dengue, Hantavirus, Japanese Encephalitis Virus, Leishmaniasis, Lyme disease, malaria, schistosomiasis, and others.
  • Tertiary health effects
    • Water changes including stocks and flows of reservoir water such as groundwater recharging and glaciers/snowpack
    • Sea water elevation can cause local changes in water quality (increased bacterial or environmental toxins) with decreased fishing, arable or grazing land.
  • Changes in food and water supplies and land availability can lead to increased epidemics, population stress, conflict, population displacement and deteriorating social structure
    • “Displacement typically entails increased risks to health from undernutrition, infectious diseases, conflict situations, mental health problems – and from changes in health related behaviors such as alcohol consumption, tobacco smoking and transactional sex.”

On the potential positive side, some climatic changes can benefit some regions such as cold-weather areas will have fewer strokes or myocardial infarctions due to winter weather. Temperate areas that become even warmer could have drier conditions and therefore fewer mosquito-borne infectious diseases as there is less water for breeding and decreased lifespan.

Questions for Further Discussion
1. What climate change health conditions have you seen locally?
2. What climate change health conditions could you expect in your local area?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Climate Change, Environmental Health, and International Health.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Kurane I. The effect of global warming on infectious diseases. Osong Public Health Res Perspect. 2010 Dec;1(1):4-9.

McMichael AJ, Lindgren E. Climate change: present and future risks to health, and necessary responses. J Intern Med. 2011 Nov;270(5):401-13.

Bai L, Morton LC, Liu Q. Climate change and mosquito-borne diseases in China: a review. Global Health. 2013 Mar 9;9:10.

Tian HY, Bi P, Cazelles B, Zhou S, et.al.. How environmental conditions impact mosquito ecology and Japanese encephalitis: an eco-epidemiological approach. Environ Int. 2015 Jun;79:17-24.

Ahdoot S, Pacheco SE; Council on Environmental Health. Global Climate Change and Children’s Health. Pediatrics. 2015 Nov;136(5):e1468-84.

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital

Safety Risks of Baltic Amber Teething Necklaces and Similar Cultural Practices?

Patient Presentation
A 10-month-old female came to clinic with fever for 24 hours and pulling on her ears. She had had upper respiratory tract infection symptoms and was not sleeping well for 2 days. The past medical history was unremarkable.

The pertinent physical exam showed a slightly cranky but consolable female who was afebrile and had growth parameters in the 50-75%. HEENT showed bilateral bulging eardrums with loss of landmarks, erythema, and no movement with insufflation. She had an amber-colored teething necklace around her neck. Her lungs were clear and her skin showed no rashes. The rest of her examination was negative.

The diagnosis of a female with bilateral supprative otitis media was made and oral antibiotics were prescribed. The pediatrician asked the mother about the necklace. “It’s an amber teething necklace to help her with teething. She has a lot of drooling and I think this helps,” the mother said. The pediatrician discussed that the necklace posed a choking hazard. “Oh, she only has it on when she is awake and I can watch her,” the mother responded. “I understand that that is always your intention, but things can happen like her falling asleep and you forgetting to take it off,” he said, and added “We don’t recommend any jewelry for children because of the risks, but if you are going to use it, can it be pinned to the inside of the clothing still touching the skin, or even placed on an ankle where it is less likely for her to be strangled or for her to get a loose bead into her mouth?” The mother didn’t respond. At a routine health supervision visit, the child was still wearing the necklace on her neck. The pediatrician again tried to engage the mother about the potential risks and was told directly that the mother intended for the child to continue to wear it around her neck.

Discussion
Amber is fossilized tree resin that is prized for its beautiful colors from deep brown to caramel, yellow, green or even white. It is promoted for its “healing properties” although there is not scientific evidence that supports the many potentiated mechanisms of these properties. One of the most consistent is that amber contains succinic acid which proponents believe is absorbed through the skin and is a pain reliever. Succinic acid was actually first purified from amber in 1546 by a German chemist. Succinic acid in humans is an important part of the Krebs cycle and acts as an important metabolite in several metabolic pathways including hypoxia, tumorigenesis, superoxide radicals and in inflammation. Elevated succinate occurs in various disease states including hypertension, inflammatory bowel disease and type 2 diabetes in animal models and bacteria. Even with increased amounts of succinic acid in an amber teething necklace, the amount that would be have to be released, then absorbed through the skin (which is difficult) and then make it through the circulatory system to potential mediators of dental inflammation is certainly not a therapeutic amount. Amber necklaces may not even be amber as plastic, glass, phenolic resins and copal are easily substituted and passed off as real amber. Real amber is relatively expensive and many items on the market that claim to be amber are not.

Teething occurs usually from 6-30 months with the eruption of 20 primary teeth. The individual tooth eruption occurs over ~7-8 days which includes the 4 days before and 3 days after the eruption. While many people attribute many symptoms to teething including fevers and diarrhea, there is not much evidence that supports these ideas. Some children will have some discomfort for a short amount of time around eruption and may have more drooling around this time. This is also a time period during the child’s life when many other childhood illnesses occur especially viral illnesses.

Recommended options for teething symptoms includes:

  • Gum massage with soft cloth or clean fingers
  • Chewing items that are chilled, not frozen as they are too hard. Rubber teething rings are one such item. All items, but especially plastic teething rings, should be cleaned following the manufacturer’s instructions. Plastic rings placed in boiling water or a dishwasher may lose their integrity.
  • Unsweetened teething biscuits or rusks for children > 6 months who are eating solid foods
  • Oral pain relievers such as acetaminophen or ibuprofen. Oral teething gels containing benzocaine are not recommended because of the risk for methemoglobinemia.
  • Drying saliva on the skin to prevent irritation

Learning Point
Because of the strangulation risk, in 2010, the Canadian federal public health department issued a consumer product safety warning. France and Switzerland also have banned sales of amber teething necklaces in their pharmacies.
A study from France, showed that even when families are given the information about amber necklaces risks, they often still continue the practice. “When informed of the danger of strangulation, numerous families preferred to continue this practice: their irrational fear of seeing their child suffer [while teething] surpassed their fear of the risk of strangulation[,]” the study concluded.

Risks for amber necklaces include:

  • Strangulation – manufacturing standards are lacking and therefore safety clasps may not be present or may not work
  • Choking hazards – beads or other necklace parts could be ingested and/or aspirated. Some believe that individual knotting between the beads only allows 1-2 beads to fall off if the necklace is broken, but even 1-2 beads can cause a choking hazard
  • Infectious disease – amber necklaces are highly colonized with commensal bacterial with a median of 4 bacteria/necklace (range 1-9) mainly coagulase-negative Staphylococci. These bacteria could become pathogenic in the right conditions.

It is important for health care providers to try to work with parents to understand the cultural, religious, or other significance of necklaces, bracelets, strings, or other bodily adornments that often encircle the neck, extremity or body of children. For some, the item was given by a family member or friend and the parents want to honor that person by having the young child wear the item. For others, it is a customary practice which parents follow and may or may not be aware of the reasons for the practice. For many families discussing with them the reasons for the practice and what is important about the practice and needs to be maintained, usually helps to clarify expectations. For example, for some Hispanic families, gold necklaces and bracelets are believed to ensure general safety of the child, and for many of these families the item does not have to encircle the body but just needs to be touching the skin to maintain its believed effectiveness. Some of these families will remove the item or be willing to move it to another location on the body or pin it inside the clothing to decrease the risks but still maintain skin contact with the item.

For a review of risks in everyday life click here.

Questions for Further Discussion
1. What other cultural or religious practices do you see in your practice that have potential health or safety risks?
2. How do you advise families about these risks?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Child Safety and Child Dental Health.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Taillefer A, Casasoprana A, Cascarigny F, Claudet I. Infants wearing teething necklaces. Arch Pediatr. 2012 Oct;19(10):1058-64.

Jacobson R. Amber Teething Necklaces Pose Choking Hazard. New York Times. October 11, 2013. Available from the Internet at http://well.blogs.nytimes.com/2013/10/11/amber-teething-necklaces-pose-choking-hazard/?_r=0 (cited 12/20/16).

Snyder S. Amber Waves of Woo. Science-Based Medicine. April 11, 2014. Available from the Internet at https://sciencebasedmedicine.org/amber-waves-of-woo/ (cited 12/20/16).

Mills E, O’Neill LA. Succinate: a metabolic signal in inflammation. Trends Cell Biol. 2014 May;24(5):313-20.

Tretter L, Patocs A, Chinopoulos C. Succinate, an intermediate in metabolism, signal transduction, ROS, hypoxia, and tumorigenesis. Biochim Biophys Acta. 2016 Aug;1857(8):1086-101.

Machet P, Lanotte P, Giraudeau B, Leperlier M, Tavernier E, Maruani A. Amber necklaces: reasons for use and awareness of risk associated with bacterial colonisation. Eur J Dermatol. 2016 Nov 21. [Epub ahead of print]

Cox C, Petrie N, Hurley KF. Infant Strangulation from an Amber Teething Necklace. CJEM. 2016 Aug 9:1-4. [Epub ahead of print]

Australian Academy of Paediatric Dentistry. Teething. Available from the Internet at http://aapd.org.au/articles/teething (cited 12/20/16).

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital