Disease outbreaks and other matters of airline medical interest

Here is another update carrying on from last week. In the previous update I introduced to you the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) report on cabin air quality and occupational health of air crew, which you can access here https://www.anses.fr/fr/system/files/AIR2019SA0075Ra.pdf (in full, in French) and here https://www.anses.fr/en/content/health-flight-crew-members  (short summary in English).

The report concludes that there is a low level of evidence for the existence of a syndrome specifically linked to exposure to various polluting substances or breakdown products from aircraft engine or hydraulic fluid leaks, and that there is no consensus to date around whether “aerotoxic syndrome” corresponds to an actual nosological entity (i.e. a syndrome or a disease).

The ANSES report also addressed the potential effects of irregular hours and ionising radiation. Here is a sum-up of the report’s conclusions.

Published data regarding commercial airline pilots and cabin crew confirm a lower incidence of a number of malignancies than in the general population, in particular cancer of the lungs, bladder, kidney, colon, brain and mouth. The incidence of testicular, colorectal and thyroid cancer was found to be similar to that in the general population, while the small number of published studies and failure to take into account potential but relevant confounding factors do not allow for a conclusion regarding the risk of prostate or breast cancer.

On the other hand, data point to an increase in the occurrence of certain types of cancer possibly linked to professional activity, in particular skin cancer (melanoma, squamous cell or basal cell cancer) and leukaemia in pilots. However, except for melanoma, aggregated mortality is lower than in the general population. According to the report, controlled levels of ionising radiation and UV exposure favour the hypothesis that non-occupational factors and frequent medical examinations, with more frequent screening, may explain higher incidence and lower mortality than in the reference population.

The WHO International Agency for Research on Cancer (IARC) has addressed various risk factors to which aircrew have been or are exposed to during their professional career: passive smoking, several types of radiation and night shift work. In 2020, the IARC classified night shift work as "probably carcinogenic to humans", based on "limited evidence of cancer in humans", "sufficient evidence of cancer in experimental animals” and “strong mechanistic evidence of cancer in experimental animals”. More studies are needed.

Concerning non-neoplastic diseases, the ANSES assessment did not find an increase in the risk of cardiovascular and respiratory diseases, musculoskeletal disorders, or psycho-social disorders, nor any effects on female reproduction among flight crews.

Overall, the ANSES report is somewhat reassuring, but these are vast and complex topics, and more studies are needed.

From the ECDC (European Centre for Disease Prevention and Control) Weekly Communicable Disease Threats Report:

  • Since mid-November, over 14,000 new cholera cases have been reported worldwide, namely from Bangladesh, Cameroon, China, Democratic Republic of the Congo, Ethiopia, Haiti, India, Kenya, Malawi, Mozambique, Philippines, Somalia, Sudan, Syria, Thailand, United Republic of Tanzania, Zambia, and Zimbabwe. In recent months, cholera cases have continued to be reported in western, eastern and southern parts of Africa, some parts of the Middle East, South-East Asia and the Americas. The risk of cholera infection in travellers visiting these countries remains low.
  • SARS-CoV-2 and seasonal influenza are currently co-circulating in Europe and elsewhere in the temperate Northern Hemisphere.

Links to selected articles/publications of interest:

  • From the Journal of Travel Medicine, a colour-coded map based on a score defined by the authors on the risk of diseases transmitted by the faecal-oral route, i.e., essentially transmitted through food and water. The score has limitations but it’s interesting for a quick glance of risk in very broad terms.

Dieter Stürchler, Infections transmitted via the faecal–oral route: a simple score for a global risk map, Journal of Travel Medicine, Volume 30, Issue 6, August 2023, taad069, https://doi.org/10.1093/jtm/taad069

To find out more about this score: https://academic.oup.com/jtm/article/30/6/taad069/7158049

Wishing you all the best for 2024!

Dr Rui Pombal
IATA Medical Advisor