As long as you stay up to date with your vaccinations and take basic preventive measures, you'd have to be pretty unlucky to succumb to most of the health hazards we mention. Africa certainly has an impressive selection of tropical diseases on offer, but you're more likely to get a bout of diarrhoea (in fact, you should bank on it), a cold or an infected mosquito bite than an exotic disease such as sleeping sickness. When it comes to injuries (as opposed to illness), the most likely reason for needing medical help in West Africa is as a result of road accidents – vehicles are rarely well maintained, the roads are potholed and poorly lit, and drink-driving is common.
It's a formidable list for West Africa, but, as we say, a few precautions go a long way…
Although small outbreaks can occur, cholera is usually only a problem during natural or human-made disasters. Travellers are rarely affected. It is caused by a bacteria and spread via contaminated drinking water. The main symptom is profuse, watery diarrhoea, which causes debilitation if fluids are not replaced quickly. An oral cholera vaccine is available, but it is not particularly effective. Most cases of cholera could be avoided by making sure you drink clean water and by avoiding potentially contaminated food. Treatment is by fluid replacement (orally or via a drip), but sometimes antibiotics are needed. Self-treatment is not advised.
Found in Senegal, Burkina Faso, Guinea, and some parts of East and Southern Africa, dengue fever (also called 'breakbone fever') is spread by mosquito bites. It causes a feverish illness with headache and muscle pains similar to those experienced with a bad, prolonged attack of influenza. There might be a rash. Self-treatment: paracetamol and rest. In rare cases in Africa this becomes Severe Dengue Fever, with worsening symptoms including vomiting, rapid breathing and abdominal pain. Seek medical help as this can be fatal.
Spread through close respiratory contact, diphtheria is found in all of Africa. It usually causes a temperature and a severe sore throat. Sometimes a membrane forms across the throat, and a tracheostomy is needed to prevent suffocation. Vaccination is recommended for those likely to be in close contact with the local population in infected areas. More important for long stays than for short-term trips, the vaccine is given as an injection alone or with tetanus, and lasts 10 years.
Tiny worms migrating in the lymphatic system cause filariasis. It is found in most of West, Central, East and Southern Africa, and in Sudan in North Africa. A bite from an infected mosquito spreads the infection. Symptoms include itching and swelling of the legs and/or genitalia. Treatment is available.
Found in all of Africa, hepatitis A is spread through contaminated food (particularly shellfish) and water. It causes jaundice and is rarely fatal, but can cause prolonged lethargy and delayed recovery. If you've had hepatitis A, you shouldn't drink alcohol for up to six months after, but once you've recovered, there won't be any long-term problems. The first symptoms include dark urine and a yellow colour to the whites of the eyes. Sometimes a fever and abdominal pain might occur. Hepatitis A vaccine (Avaxim, VAQTA, Havrix) is given as an injection: a single dose will give protection for a year, and a booster after a year gives 10-year protection. Hepatitis A and typhoid vaccines can also be given as a single-dose vaccine (Hepatyrix or Viatim).
Spread through infected blood, contaminated needles and sexual intercourse, Hepatitis B is found in Africa. It can be spread from an infected mother to the baby in childbirth. It affects the liver, causing jaundice and occasionally liver failure. Most people recover completely, but some might be chronic carriers of the virus, which can lead eventually to cirrhosis or liver cancer. Those visiting high-risk areas for long periods or with increased social or occupational risk should be immunised. Many countries now give Hepatitis B as part of the routine childhood vaccination. It is given singly or can be given at the same time as Hepatitis A (Hepatyrix).
A course of vaccinations will give protection for at least five years. It can be given over four weeks or six months.
Human immunodeficiency virus (HIV), the virus that causes acquired immune deficiency syndrome (AIDS), is a huge problem in Africa but is most acutely felt in sub-Saharan Africa. The virus is spread through infected blood and blood products, by sexual intercourse with an infected partner, and from an infected mother to her baby during childbirth and breastfeeding. It can be spread through 'blood to blood' contacts, such as with contaminated instruments during medical, dental, acupuncture and other body-piercing procedures, and through sharing intravenous needles. At present there is no cure; medication that might keep the disease under control is available, but these drugs are too expensive for the overwhelming majority of Africans, and are not readily available for travellers either. If you think you might have been infected with HIV, a blood test is necessary; a three-month gap after exposure and before testing is required to allow antibodies to appear in the blood.
This is found in West and Southern Africa; in Chad and the Democratic Republic of the Congo in Central Africa; in Algeria, Morocco and Sudan in North Africa; and in Ethiopia and Somalia in East Africa. It is spread through the excreta of infected rodents, especially rats. It can cause hepatitis and renal failure, which might be fatal. It is unusual for travellers to be affected unless they're living in poor sanitary conditions. It causes a fever and sometimes jaundice.
Malaria is a widespread risk in West Africa and the risk of catching it should be taken seriously. The disease is caused by a parasite in the bloodstream spread via the bite of the female Anopheles mosquito. There are several types of malaria. Infection rates vary with season and climate, so check out the situation before departure. Several different drugs are used to prevent malaria, and new ones are in the pipeline. Up-to-date advice from a travel health clinic is essential as some medication is more suitable for some travellers than others (eg people with epilepsy should avoid mefloquine, and doxycycline should not be taken by pregnant women or children aged under 12).
The early stages of malaria include headaches, fevers, generalised aches and pains, and malaise, which could be mistaken for flu. Other symptoms can include abdominal pain, diarrhoea and a cough. Anyone who develops a fever in a malarial area should assume malarial infection until a blood test proves negative, even if you have been taking antimalarial medication. If not treated, the next stage could develop within 24 hours, particularly if falciparum malaria is the parasite: jaundice, then reduced consciousness and coma (also known as cerebral malaria), followed by death. Treatment in hospital is essential, and the death rate might still be as high as 10% even in the best intensive-care facilities.
Many travellers think that malaria is a mild illness, and that taking antimalarial drugs causes more illness through side effects than actually getting malaria. This is unfortunately not true. If you decide against antimalarial drugs, you must understand the risks, and be obsessive about avoiding mosquito bites. Use nets and insect repellent, and report any fever or flulike symptoms to a doctor as soon as possible. Some people advocate homeopathic preparations against malaria, such as Demal200, but as yet there is no conclusive evidence that this is effective, and many homeopaths do not recommend their use.
Malaria in pregnancy frequently results in miscarriage or premature labour, and the risks to both mother and foetus during pregnancy are considerable. Travel throughout the region when pregnant should be carefully considered. Adults who have survived childhood malaria have developed immunity and usually only develop mild cases of malaria; most Western travellers have no immunity at all. Immunity wanes after 18 months of nonexposure, so even if you have had malaria in the past and used to live in a malaria-prone area, you might no longer be immune.
A – Awareness of the risk. No medication is totally effective, but protection of up to 95% is achievable with most drugs, as long as other measures have been taken.
B – Bites: avoid at all costs. Sleep in a screened room, use a mosquito spray or coils, sleep under a permethrin-impregnated net. Cover up at night with long trousers and long sleeves, preferably with permethrin-treated clothing. Apply appropriate repellent to all areas of exposed skin in the evenings.
C – Chemical prevention (ie antimalarial drugs). These are usually required in malarial areas. Expert advice is needed as resistance patterns can change, and new drugs are in development. Not all antimalarial drugs are suitable for everyone. Most antimalarial drugs need to be started at least a week in advance and continued for four weeks after the last possible exposure to malaria.
D – Diagnosis. If you have a fever or flu-like illness within a year of travel to a malarial area, malaria is a possibility, and immediate medical attention is necessary.
Meningococcal infection is spread through close respiratory contact and is more likely in crowded situations, such as dormitories, buses and clubs. Infection is uncommon in travellers. Vaccination is recommended for long stays and is especially important towards the end of the dry season, which varies across the continent. Symptoms include a fever, severe headache, neck stiffness and a red rash. Immediate medical treatment is necessary.
The ACWY vaccine is recommended for all travellers in sub-Saharan Africa. This vaccine is different from the meningococcal meningitis C vaccine given to children and adolescents in some countries; it is safe to be given both types of vaccine.
Also known as 'river blindness', this is caused by the larvae of a tiny worm, which is spread by the bite of a small fly. The earliest sign of infection is intensely itchy, red, sore eyes. Travellers are rarely severely affected. Treatment in a specialised clinic is curative.
Polio is generally spread through contaminated food and water. The vaccine is one of those given in childhood and should be boosted every 10 years, either orally (a drop on the tongue) or as an injection. Polio can be carried asymptomatically (ie showing no symptoms) and could cause a transient fever. In rare cases it causes weakness or paralysis of one or more muscles, which might be permanent. Niger and and Nigeria have both suffered recent outbreaks.
Rabies is spread by receiving the bites or licks of an infected animal on broken skin. It's fatal once the clinical symptoms start (which might be up to several months after the injury), so post-bite vaccination should be given as soon as possible. Post-bite vaccination (whether or not you've been vaccinated before the bite) prevents the virus from spreading to the central nervous system. Animal handlers should be vaccinated, as should those travelling to remote areas where a source of post-bite vaccine is not available within 24 hours. Three preventative injections are needed in a month. If you have not been vaccinated you will need a course of five injections starting 24 hours or as soon as possible after the injury. If you have been vaccinated, you will need fewer post-bite injections and will have more time to seek medical aid.
Also called bilharzia, this disease is spread by flukes that are carried by a species of freshwater snail. The flukes are carried inside the snail, which then sheds them into slow-moving or still water. The parasites penetrate human skin during paddling or swimming and then migrate to the bladder or bowel. They are passed out via stools or urine and can contaminate fresh water, where the cycle starts again. Avoid paddling or swimming in suspect freshwater lakes or slow-running rivers. There may be no symptoms or there may be a transient fever and rash, and advanced cases can have blood in the stool or in the urine. A blood test can detect antibodies if you have been exposed, and treatment is then possible in travel- or infectious-disease clinics. If not treated, the infection can cause kidney failure or permanent bowel damage. It isn't possible for you to infect others.
TB is spread through close respiratory contact and occasionally through infected milk or milk products. BCG (Bacille Calmette-Guérin) vaccination is recommended for those likely to be mixing closely with the local population, although it gives only moderate protection against TB. It is more important for long stays than for short-term stays. Inoculation with the BCG vaccine is not available in all countries. It is given routinely to many children in developing countries. The vaccination causes a small, permanent scar at the injection site and is usually given in a specialised chest clinic. It is a live vaccine and should not be given to pregnant women or immunocompromised individuals.
TB can be asymptomatic, only being picked up on a routine chest X-ray. Alternatively, it can cause a cough, weight loss or fever, sometimes months or even years after exposure.
This is spread through food or water contaminated by infected human faeces. The first symptom is usually a fever or a pink rash on the abdomen. Sometimes septicaemia (blood poisoning) can occur. A typhoid vaccine (typhim Vi, typherix) will give protection for three years. In some countries, the oral vaccine Vivotif is also available. Antibiotics are usually given as treatment, and death is rare unless septicaemia occurs.
Spread via the bite of the tsetse fly, trypanosomiasis, also called 'sleeping sickness', causes a headache, fever and eventually coma. There is an effective treatment.
Travellers should carry a certificate as evidence of vaccination if they have recently been in an infected country, to avoid any possible difficulties with immigration. For a full list of these countries visit the websites of WHO (www.who.int/en) or the Centers for Disease Control and Prevention (wwwnc.cdc.gov/travel). There is always the possibility that a traveller without a legally required, up-to-date certificate will be vaccinated and detained in isolation at the port of arrival for up to 10 days, or possibly repatriated.
Yellow fever is spread by infected mosquitoes. Symptoms range from a flu-like illness to severe hepatitis (liver inflammation), jaundice and death. The yellow-fever vaccination must be given at a designated clinic and is valid for 10 years. It is a live vaccine and must not be given to immunocompromised or pregnant travellers.
Heat exhaustion is a precursor to the much more serious heatstroke. In this case there is damage to the sweating mechanism, with an excessive rise in body temperature; irrational and hyperactive behaviour; and eventually loss of consciousness and death. Rapid cooling by spraying the body with water and fanning is best. Emergency fluid and electrolyte replacement is required by intravenous drip.
Mosquitoes might not always carry malaria or dengue fever, but they (and other insects) can cause irritation and infected bites. To avoid these, take the same precautions as you would for avoiding malaria. Use DEET-based insect repellents. Excellent clothing treatments are also available; mosquitos that land on treated clothing will die.
Bee and wasp stings cause real problems only to those who have a severe allergy to the stings (anaphylaxis). If you are one of these people, carry an EpiPen – an adrenaline (epinephrine) injection, which you can give yourself. This could save your life.
Sandflies are found around the beaches. They usually only cause a nasty, itchy bite but can carry a rare skin disorder called cutaneous leishmaniasis. Prevention of bites with DEET-based repellents is sensible.
Scorpions are frequently found in arid or dry climates. They have a painful sting that is sometimes life-threatening. If stung by a scorpion, seek immediate medical assistance.
Bed bugs are found in hostels and cheap hotels and lead to itchy, lumpy bites. Spraying the mattress with crawling-insect killer after changing bedding will get rid of them.
Scabies are also found in cheap accommodation. These tiny mites live in the skin, often between the fingers, and they cause an intensely itchy rash. The itch is easily treated with malathion and permethrin lotion from a pharmacy; other members of the household also need treating to avoid spreading scabies, even if they do not show any symptoms.
In Gabon and neighbouring countries, the fourou is tiny insect you can neither see nor hear: it bites between 5pm and 6.30pm, is not deterred by anti-mosquito spray and can fly straight through mosquito nets. It leaves very itchy red welts on the skin.
Avoid getting bitten! Don't walk barefoot, or stick your hand into holes or cracks. However, 50% of those bitten by venomous snakes are not actually injected with poison. If bitten by a snake, do not panic. Immobilise the bitten limb with a splint (such as a stick) and apply a bandage over the site with firm pressure (similar to bandaging a sprain). Do not apply a tourniquet, or cut or suck the bite. Get medical help as soon as possible so antivenin can be given if needed. It will help get you the correct antivenin if you can identify the snake, so try to take note of its appearance.
This condition occurs following heavy sweating and excessive fluid loss with inadequate replacement of fluids and salt, and is common in hot climates when taking exercise before full acclimatisation. Symptoms include headache, dizziness and tiredness. Dehydration is happening by the time you feel thirsty – aim to drink sufficient water to produce pale, diluted urine. Treatment involves fluid replacement with water and/or fruit juice, and cooling by cold water and fans. The treatment of the salt-loss component consists of consuming salty fluids, as in soup, and adding a bit more salt to food than usual.
At least 80% of the African population relies on traditional medicine, often because conventional Western-style medicine is too expensive, because of prevailing cultural attitudes and beliefs, or simply because in some cases it works. It might also be because there's no other choice: a WHO survey found that, although there was only one medical doctor for every 50,000 people in Mozambique, there was a traditional healer for every 200 people.
Although some African remedies seem to work on malaria, sickle cell anaemia, high blood pressure and some AIDS symptoms, most African healers learn their art by apprenticeship, so education (and consequently application of knowledge) is inconsistent and unregulated. Conventionally trained physicians in South Africa, for example, angrily describe how their AIDS patients die of kidney failure because a sangoma (traditional healer) has given them an enema containing an essence made from powerful roots. Likewise, when traditional healers administer 'injections' with porcupine quills, knives or dirty razor blades, diseases are often spread or created rather than cured.
Rather than attempting to stamp out traditional practices, or pretend they aren't happening, a positive step taken by some African countries is the regulation of traditional medicine by creating healers' associations and offering courses on such topics as sanitary practices. It remains unlikely in the short term that even a basic level of conventional Western-style medicine will be made available to all the people of Africa (even though the cost of doing so is less than the annual military budget of some Western countries). Traditional medicine, on the other hand, will almost certainly continue to be practised widely throughout the continent.
It's not inevitable that you will get diarrhoea while travelling in Africa, but it's certainly likely. Diarrhoea is the most common travel-related illness – figures suggest that at least half of all travellers to Africa will get diarrhoea at some stage. Sometimes dietary changes, such as increased spices or oils, are the cause. To help prevent diarrhoea, avoid tap water unless you're sure it's safe to drink. You should only eat cooked or peeled fresh fruits or vegetables, and be wary of dairy products that might contain unpasteurised milk. Although freshly cooked food can often be a safe option, plates or serving utensils might be dirty, so you should be very selective when eating food from street vendors (make sure that cooked food is piping hot all the way through). If you develop diarrhoea, be sure to drink plenty of fluids, preferably an oral rehydration solution containing water, and some salt and sugar. A few loose stools don't require treatment, but if you start having more than four or five a day you should start taking an antibiotic (often a quinoline drug, such as ciprofloxacin or norfloxacin) and an anti-diarrhoeal agent (such as loperamide) if you are not within easy reach of a toilet. If diarrhoea is bloody, persists for over 72 hours or is accompanied by fever, shaking, chills or severe abdominal pain, you should seek medical attention.
Contracted by eating contaminated food and water, amoebic dysentery causes blood and mucus in the faeces. It can be relatively mild and tends to come on gradually, but seek medical advice if you think you have the illness, as it won't clear up without treatment (which is with specific antibiotics).
Like amoebic dysentery, this is caused by ingesting contaminated food or water. The illness appears a week or more after you have been exposed to the parasite. Giardiasis might cause only a short-lived bout of traveller's diarrhoea, but it can cause persistent diarrhoea. Seek medical advice if you suspect you have giardiasis, but if you are in a remote area you could start a course of antibiotics.
Never drink tap water unless it has been boiled, filtered or chemically disinfected (eg with iodine tablets).
Also, never drink from streams, rivers or lakes. It's best to avoid drinking from pumps and wells – some do bring pure water to the surface, but the presence of animals can contaminate supplies.
Health care in West Africa is varied: it can be excellent in the major cities, which generally have well-trained doctors and nurses, but it is often patchy off the beaten track. Medicine and even sterile dressings and intravenous fluids might need to be purchased from a local pharmacy by patients or their relatives. The standard of dental care is equally variable, and there is an increased risk of hepatitis B and HIV transmission via poorly sterilised equipment. By and large, public hospitals in Africa offer the cheapest service, but will have the least up-to-date equipment and medications; mission hospitals (where donations are the usual form of payment) often have more reasonable facilities; and private hospitals and clinics are more expensive but tend to have more advanced drugs and equipment and better-trained medical staff.
Most drugs can be purchased over the counter in West Africa, without a prescription. Many drugs for sale in West Africa might be ineffective: they might be counterfeit or might not have been stored under the right conditions. The most common examples of counterfeit drugs are malaria tablets and expensive antibiotics, such as ciprofloxacin. Most drugs are available in capital cities, but remote villages will be lucky to have a couple of paracetamol tablets. It is recommended that all drugs for chronic diseases be brought from home. Also, the availability and efficacy of condoms cannot be relied on – bring contraception. Condoms bought in West Africa might not be of the same quality as in Europe or Australia, and they might not have been correctly stored.
There is a high risk of contracting HIV from infected blood if you receive a blood transfusion in West Africa. To minimise this, seek out treatment in reputable clinics. If you have any doubts, the Blood Care Foundation (www.bloodcare.org.uk) is a useful source of safe, screened blood, which can be transported to any part of the world within 24 hours.
The cost of health care might seem cheap compared to its cost in developed countries, but good care and drugs might not be available. Evacuation to good medical care (within West Africa or to your own country) can be very expensive. Unfortunately, adequate health care is available only to very few West Africans.
The World Health Organization (www.who.int/en) recommends that all travellers be covered for diphtheria, tetanus, measles, mumps, rubella and polio, as well as for hepatitis B, regardless of their destination. Planning to travel is a great time to ensure that all routine vaccination cover is complete. The consequences of these diseases can be severe, and outbreaks do occur.
According to the Centers for Disease Control and Prevention (wwwnc.cdc.gov/travel), the following vaccinations are recommended for all parts of Africa: hepatitis A, hepatitis B, meningococcal meningitis, rabies and typhoid, and boosters for tetanus, diphtheria and measles. Yellow-fever vaccination is not necessarily recommended for all parts of West Africa, although the certificate is an entry requirement for many countries.
North Africa Not mandatory for any of North Africa, but Algeria, Libya and Tunisia require evidence of yellow-fever vaccination if entering from an infected country. It is recommended for travellers to Sudan, and might be given to unvaccinated travellers leaving the country.
Central Africa Mandatory in Central African Republic (CAR) and the Democratic Republic of the Congo, and recommended in Chad.
West Africa Mandatory in Benin, Burkina Faso, Cameroon, Côte d'Ivoire, Equatorial Guinea, Gabon, Ghana, Liberia, Mali, Niger, the Republic of Congo, São Tomé & Príncipe and Togo, and recommended for The Gambia, Guinea, Guinea-Bissau, Mauritania, Nigeria, Senegal and Sierra Leone.
East Africa Mandatory in Rwanda; it is advised for Burundi, Ethiopia, Kenya, Somalia, Tanzania and Uganda.
Southern Africa Not mandatory for entry into any countries of Southern Africa, although it is necessary if entering from an infected country.
Find out in advance whether your insurance plan will make payments to providers or will reimburse you later for overseas health expenditures (in many countries doctors expect payment in cash). It's vital to ensure that your travel insurance will cover the emergency transport required to get you to a hospital in a major city, to better facilities elsewhere in Africa, or all the way home by air and with a medical attendant if necessary. Not all insurance covers this, so check the contract carefully. If you need medical help, your insurance company might be able to help locate the nearest hospital or clinic, or you can ask at your hotel. In an emergency, contact your embassy or consulate.
The African Medical and Research Foundation (www.amref.org) provides an air-evacuation service in medical emergencies in some African countries, as well as air-ambulance transfers between medical facilities. Money paid by members to their flying doctor service entitles you to air-ambulance evacuation, and the funds go into providing grass-roots medical assistance for local people.
It is a very good idea to carry a medical and first aid kit with you, to help yourself in the case of minor illness or injury. Following is a list of items you should consider packing.
If you are travelling through a malarial area – particularly an area where falciparum malaria predominates – consider taking a self-diagnostic kit that can identify malaria in the blood from a finger prick.
A Comprehensive Guide to Wilderness and Travel Medicine (1998) by Eric A Weiss
The Essential Guide to Travel Health (2009) by Jane Wilson-Howarth
Healthy Travel Africa (2000) by Isabelle Young
How to Stay Healthy Abroad (2002) by Richard Dawood
Travel in Health (1994) by Graham Fry
Lonely Planet's Travel with Children (2015) by Sophie Caupeil et al
There is a wealth of travel-health advice on the internet. Lonely Planet (www.lonelyplanet.com) is a good place to start. The World Health Organization publishes the helpful International Travel and Health, available free at www.who.int/ith. Other useful websites include MD Travel Health (www.mdtravelhealth.com) and Fit for Travel (www.fitfortravel.scot.nhs.uk).
Official government travel health websites:
A little planning before departure, particularly for pre-existing illnesses, will save you a lot of trouble later. Before a long trip get a check-up from your dentist, and from your doctor if you have any regular medication or a chronic illness, such as high blood pressure or asthma. You should also organise spare contact lenses and glasses (and take your optical prescription with you), get a first aid and medical kit together, and arrange necessary vaccinations.
It's tempting to leave it all to the last minute – don't! Many vaccines don't take effect until two weeks after you've been immunised, so visit a doctor four to eight weeks before departure. Ask your doctor for an International Certificate of Vaccination (otherwise known as the yellow booklet or livre jaune), which will list all the vaccinations you've received. This is mandatory for the African countries that require proof of yellow-fever vaccination upon entry, but it's a good idea to carry it anyway wherever you travel in case you require medical treatment or encounter troublesome border officials.
Travellers can register with the International Association for Medical Advice to Travellers (www.iamat.org). Its website can help travellers find a doctor who has recognised training. Those heading off to very remote areas might like to do a first-aid course (contact the Red Cross or St John Ambulance) or attend a remote medicine first-aid course, such as that offered by the Royal Geographical Society (www.wildernessmedicaltraining.co.uk).
If you are bringing medications with you, carry them in their original containers, clearly labelled. A signed and dated letter from your physician describing all medical conditions and medications, including generic names, is also a good idea. If carrying syringes or needles, be sure to have a physician's letter documenting their medical necessity.
If you're crossing more than five time zones you could suffer jet lag, resulting in insomnia, fatigue, malaise or nausea. To avoid jet lag drink plenty of (nonalcoholic) fluids and eat light meals. Upon arrival, get exposure to natural sunlight and readjust your schedule (for meals, sleep, etc) as soon as possible.
Antihistamines such as dimenhydrinate (Dramamine) and meclizine (Antivert, Bonine) are usually the first choice for treating motion sickness. The main side effect of these drugs is drowsiness. A herbal alternative is ginger (in the form of ginger tea, ginger biscuits or crystallised ginger), which works like a charm for some people.
Blood clots can form in the legs during flights, chiefly because of prolonged immobility. This formation of clots is known as deep vein thrombosis (DVT), and the longer the flight, the greater the risk. Although most blood clots are reabsorbed uneventfully, some might break off and travel through the blood vessels to the lungs, where they could cause life-threatening complications.
The chief symptom of DVT is swelling or pain of the foot, ankle or calf, usually but not always on just one side. When a blood clot travels to the lungs, it could cause chest pain and breathing difficulty. Travellers with any of these symptoms should immediately seek medical attention.
To prevent the development of DVT on flights you should walk about the cabin, perform isometric compressions of the leg muscles (ie contract the leg muscles while sitting), drink plenty of fluids, and avoid alcohol.