Airport malaria, sometimes known as baggage, luggage or suitcase malaria, occurs when a malaria infected female Anopheles mosquito travels by aircraft from a country where malaria is common, arrives in a country where malaria is usually not found, and bites a person at or around the vicinity of the airport, or if the climate is suitable, travels in luggage and bites a person further away. The infected person usually presents with a fever in the absence of a recent travel history. There is often no suspicion of malaria, resulting in a delay in diagnosis. It is typically considered as a diagnosis after other explanations for symptoms have been ruled out.
Most mosquitoes on aircraft do not carry malaria and the few that do are relatively inefficient invaders. The climate of the host country also offers natural protection. The detection and treatment is the same as of malaria in general. Prevention involves control of mosquitoes at and around airports in the countries of departure and on the aircraft.
Studies of airport malaria have been largely observations of individual scenarios, all unique in timing, place of infection and problems, in addition to possibilities of error. The first cases of airport malaria were reported in 1969. Climate change, the rise in international travel, and less frequent aircraft disinfection, have likely played roles in the significant increase in cases between 2010 and 2020 as compared to the previous decade in Europe.
Background
Human malaria is native to 97 countries and is the world's most prevalent vector-borne disease with 212 million new cases in 2015. Any occurrences outside endemic countries are largely imported cases or less commonly malaria with no recent travel history.
Airport malaria is defined as malaria acquired at or near an airport through the bite of an infected tropical Anopheles mosquito by a person who has no history of being exposed to the mosquitoes in their natural habitat. Malaria transmission in-flight or on a stop-over is not considered airport malaria.
Causes
Although most imported malaria is due to travel by infected humans, airport malaria is specifically caused by the transmission of malaria parasites to a human through the bite of a malaria infected mosquito that has travelled by aircraft on an international flight from a country where malaria is usually found to a country where malaria is usually not found. It occurs at or around the vicinity of the airport. Very few mosquitoes however enter aircraft and of those that do, less than 5% are likely to carry malaria. Of the four different species of the protozoan parasite Plasmodium; Plasmodium falciparum, Plasmodium malariae, Plasmodium vivax and Plasmodium ovale, airport malaria is most commonly the falciparum and less commonly the vivax type. These can only be transmitted by female Anopheles mosquitoes, which bite mainly between dusk and dawn.
Five infection pathways have been described: inside the aircraft, inside the airport, around the airport, far from the airport and from luggage.
Expansion of mosquito habitats
Deforestation, and projects involving housing, agriculture and water can incidentally expand mosquito habitats. Economic necessity, disasters and conflicts, are known to affect the migration of people, which can also contribute to the movement of mosquitoes and hence risk of malaria. Failure to take this into account has previously resulted in failed attempts to control malaria.
Air traffic and global warming
With an increase in air traffic volume, higher climate temperatures and humidity, the summers of temperate climates are potentially favourable for mosquitoes. Should temperatures rise in Europe and the United States as a result of global climate change, conditions may become more ideal for mosquito survival, potentially leading to a rise in isolated outbreaks of airport and imported malaria. Uninfected mosquitoes that arrive by flight may also live for long in enough as to feed on an infected person, which could also result in the transmission of malaria in non-endemic countries.
Airports, air routes and aircraft
Airports
The highest risk of airport malaria in Europe is from western and central Africa. A number of species have been found in these Western European airports, particularly Anopheles gambiae which breeds in Africa's rainy season during summer, when conditions in Europe are more favourable for its survival.
When the cabin and cargo hold doors are opened, ground personnel working on airstrips are at risk. Also, those who manipulate and open containers in warehouses, stores or the post office are exposed to bites of the mosquitoes which have travelled in containers.