Travel to Developing Countries

Description

Alternative Names

Travel Precautions

Vector-borne diseases are infections transmitted by insects that harbor parasitic, viral, or bacterial agents. Common diseases include yellow fever and malaria, but there are many others in every country in the world.

The risk for malaria and other mosquito-born infections is highest when mosquitoes feed, between dusk and dawn.

DEET. Most insect repellents contain the chemical DEET (N,N-diethyl-meta-toluamide), which remains the gold standard of currently available mosquito and tick repellents. Comparison studies suggest that DEET preparations are the most effective insect repellants now available. Concentrations range from 5% to almost 100%. DEET has been used for more than 40 years and is safe for even most children when used as directed.

Experts recommend that most adults and children over 12 years old use preparations containing a DEET concentration of 20% to 35% (e.g., Ultrathon), which provides complete protection for an average of five hours. (Higher DEET concentrations may be necessary for adults who are in high-risk regions for prolonged periods.) A concentration of 10% or less is recommended for children ages two to 12. In general, infants under 12 months should use non-DEET repellents, such as soybean-based Bite Blocker. Some experts believe low DEET concentrations are safe even in infants over two months old. Parents traveling to or living in high-risk areas should check with their physician.

It should be stressed that the effectiveness of DEET varies from individual to individual and depends on climate changes. For example, it can be washed off during swimming or by rain. High temperatures make it less effective. DEET, particularly in very high concentrations, can also dissolve plastics, including those used in glasses and watches and some synthetic clothing. DEET then, should not be put on clothing.

Overexposure to DEET at any age has produced toxic effects, including itching and rash and, in severe cases, irritability, insomnia, and confusion. It should be noted, however, that it has been intensively studied for 40 years and used in billions of applications. Only 50 such toxic reactions have been reported, and most of them resolved without any consequences.

When applying DEET, the following precautions should be taken:

• Do not use on the face and apply only enough to cover exposed skin on other areas.
• Do not over apply and do not use under clothing.
• Do not apply over any cuts, wounds, or irritated skin.
• Parents or an adult should apply repellent to a child and not let the child apply it him- or herself. They should first put DEET on their own hands and then apply it to the child. They should avoid putting DEET not only near the child's eyes and mouth, but also on the hands (since children frequently touch their faces).
• Wash any treated skin after going back inside.
• If using a spray, apply DEET outdoors--never indoors. Spray repellents should not be applied inside or directly on anyone's face.

Other Insect Repellent Products. In a 2002 comparison study, soy-based Bite Blocker was the only significant rival to DEET, with protection that averaged over an hour and a half. (The was slightly better than OFF! Skintastic for Kids, a 3.75% DEET product.)

The citronella- or mixed oil based products (e.g., Buzz Away, Avons Skin-so-Soft, Natrapel, Herbal Armor, Green Ban) only protected for an average of 20 minutes or less. (The lemon-citronella products offered the least protection--about 10 minutes or less.) Protection with the Bite Blocker lasts significantly longer (1.5 hours), but all of them must be applied frequently.

A synthetic insect repellent IR3535, provides protection of only 20 minutes to an hour. This product is less toxic than DEET and can be used with sunscreens (e.g., Avon Skin-So-Soft Bug Guard Plus IR3535 with Sunblock SPF 30.)

Of note, a new repellent that contains eucalyptus (Repel Lemon Eucalyptus Insect Repellent, Fite Bite Plant-Based Insect Repellent) offers protection that averages two hours and may be prove to be a good alternative, particularly for children.

Bayrepel (a piperidine derivative), a preparation used in Europe, may prove to be very protective.

The following products offer very little protection or none at all: Skin-So-Soft Bath Oil, all wristbands (including those that contain DEET or emit sound), garlic, and vitamin B1.

Use of Permethrin. Permethrin is an insect repellent used as a spray for clothing and bed nets, which can repel insects for weeks when applied correctly. Electric vaporizing mats containing permethrin may be very helpful. A permethrin solution is also available for soaking items, but should never be applied to the skin. Side effects from direct exposure may include mild burning, stinging, itching, and rash, but in general, this agent is very safe and its use may even reduce child mortality rates from malaria. Travelers allergic to chrysanthemum flowers or who are allergic to head-lice scabicides should avoid using permethrin.

Other Preventive Measures. Other preventive measures include:

• Wearing trousers and long-sleeved shirts, particularly at dusk. One survey suggested that this measure may significantly reduce the incidence of mosquito-born disease.
• Sleeping only in screened areas.
• Air-conditioning may reduce mosquito infiltration. Where air-conditioning is not available, fans may be helpful. Mosquitoes appear to be reluctant to fly in windy air.
• Not wearing perfumes.
• Minimizing skin exposure after dusk.
• Washing hair at least twice a week.
• Burning citronella candles reduces the likelihood of bites. (Indeed, burning any candle helps to some extent, perhaps because the generation of carbon dioxide diverts mosquitoes toward the flame.) Smoke from burning certain plants, including ginger, beetlenut, and coconut husks, have also reduced mosquito infiltration, but the irritating and toxic effects on the eyes and lungs may be considerable, such as the citrosa plant. To date, no evidence shows much benefit but such methods are not harmful.

Motion Sickness

About a third of the population is susceptible to motion sickness, with varying degrees of severity. The cause of motion sickness is still unclear. Some evidence suggests that, in susceptible people, motion triggers signals that the brain interprets as being unharmonious and which conflict with the brain's memory of correct position. It transmits this message to other parts of the body, which respond with sweating, nausea, salivating, and other symptoms of motion sickness. Other theories suggest that motion sickness is triggered by the body's inability to control its own posture and movement.

More women than men experience motion sickness, with one study suggesting that this may be associated with gender differences in the ability to perform spatial tasks. Women appear to be at higher risk just before and during menstruation. Motion sickness may also trigger migraines, even in people who do not ordinarily have them. Alcohol intake increases the risk of vomiting. The following are some remedies tried for motion sickness:

Medications. Prescribed medications include scopolamine in oral form or as a patch (Transderm Scop), which is worn behind the ear and releases the drug slowly. Scopolamine is the most effective drug for motion sickness. An animal study suggested that propranolol (Inderol) may be helpful. (This drug is known as a beta blocker. It blocks the nerves that stimulate the heart to beat faster and is typically used for heart conditions.)

Over-the-counter medications include dimenhydrinate (Dramamine), meclizine (Bonine), and cyclizin (Marezine). Dramamine appears to be the most rapidly effective, although in one study Marezine caused less drowsiness and was more effective at reducing nausea after 3 minutes. Cinnarizine (Stugeron) is used in Europe and appears to be effective with few side effects. It is not available in the US. None of these agents are as effective as prescription agents but may be helpful for six to 12 hours. Oral medications should be taken at least an hour before traveling to be effective.

Nearly all the medications used for motion sickness, both prescription and nonprescription, can cause drowsiness, mouth dryness, and blurred vision. Scopolamine can cause heart rhythm disturbances. In one comparison study the scopolamine patch and cinnarizine had the fewest adverse effects on functioning. Dimenhydrinate had the most.

Nonmedicinal Treatments. Common recommendations include focusing on the horizon (not on nearby areas), avoiding alcohol and strong odors. Nonmedicinal or alternative remedies are widely used, but are of unproven benefit. Some are even silly, but travelers who experience motion sickness may wish to try anything that isn't harmful. Some methods that have been tried include the following:

• Taking ginger root capsules (2000 mg) or eating large amounts of ginger starting about 12 hours before traveling. (Clinical studies are inconsistent on its benefits, with some reporting relief without side effects.)
• Acupressure (wrist bands and self pressure). Acupressure for motion involves exerting pressure on the P6 pressure point--the so-called nausea-relief point. Travelers can try pressing on the nausea-relief point, located two finger widths below the crease of the wrist on the palm-up side and between the two major tendons leading to the hand. Studies have been inconsistent on the benefits of wrist bands. Some studies have reported relief with a wristband (e.g., ReliefBand) that uses batteries that create a small electric charge at the acupuncture point. This device may cause a rash and people with pacemakers should not use it.
• Cold packs. In one study apply cold packs to the forehead reduced stomach activity motion sickness.
• Eating small meals. (Protein meals may be more effective in controlling stomach activity than carbohydrates.)
• Behavioral Techniques. Some studies have reported some relief from certain behavioral approaches, such as controlled breathing (involves simply concentrating on breathing gently or deeply) or listening to music.
• Prism glasses. In one small 2003 study, children with motion sickness achieved significant relief when they wore prism glasses (which are worn for certain learning disabilities).

Issues Involving Air Travel

Effects on Circulation. Traveling by car, airplane, or train for more than four hours increases the risk for blood clots in the legs (venous thrombosis) in anyone. In fact, studies now suggest that the it is the cause of more deaths than previously believed, because symptoms typically occur days after travel. In order to keep circulation moving during international flights or on trains, travelers should drink plenty of fluids, avoid salt, wear slippers, take frequent walks in the aisles, and lift their legs up and down several times an hour. Two 2003 studies suggested that special socks that compress the ankles (e.g., Kendall Travel Socks, Sigvaris Traveno) may significantly prevent swelling and so possibly blood clots due to long flights even in travelers at medium to low risk.

Respiratory Infections. Flight cabins have very low humidity, which not only increases the risk for dehydration and dry eyes, but it also increases the risk for triggering disease in the airways. Fliers with colds or allergies are especially susceptible. The first rule is to drink plenty of liquids. Taking a decongestant tablet or nasal spray (not one containing an antihistamine) 30 minutes before flight can help prevent sinus and ear infections.

Of greater concern are studies suggesting that the prolonged time (eight hours or more) spent in the confined space of an airplane plus the close proximity to co-passengers from the entire world may facilitate the spread of serious contagious diseases, such as tuberculosis and SARS. The CDC and World Health Organizations now have guidelines on when and how to determine the need for preventive treatments after possible exposure to infectious agents. (Recirculated air, which is now common in new aircraft, does not increase the risk for respiratory infections.)

Preventing Jet Lag. Crossing time zones can throw off the bodys natural rhythms, especially when travelers fly from west to east. But jet lag can be minimized. A few days before long flights, adjust sleeping and eating patterns:

• When traveling west, travelers might avoid outdoor light after 6 PM.
• If traveling east, travelers might begin going to bed earlier a few days before the trip and avoid outdoor light until 10 AM.
• If possible, flights should be completed well ahead of an important event requiring concentration.
• If crossing multiple time zones, the traveler should schedule overnight stopovers.
• The traveler should drink plenty of fluids, but avoid alcohol and coffee, which increase fluid loss.

Melatonin, a natural hormone associated with light changes, may help people recover from jet lag. Some people report good results by taking it on the day of departure a half hour before the expected sleeping time in the arrival city. Travelers might also ask their physicians about short-acting benzodiazepines ("sleeping pills"), such as lorazepam (Ativan), alprazolam (Xanax), or temazepam (Restoril). They have been known to cause short-term forgetfulness and other side effect.

Cruise Ships

Reports of illnesses aboard cruise ships, particularly gastrointestinal problems from contaminated food, have alarmed many travelers. A sanitation program conducted by the US Public Health Service should significantly cut the risk for such problems. Cruise ships are inspected twice a year and are then rated. The Center for Disease Controls provides ratings to the public for all ships sailing from US ports. At this time these ratings are the only guide for a healthy cruise. Meanwhile, cruise-ship travelers should avoid eating eggs and shellfish to help protect against diarrhea.

Aside from sanitation, health problems in general are common on cruise ships. A study of one major cruise ship reported that nearly 30% of the passengers were treated for skin disorders and 26% for respiratory problems while on board. Flu outbreaks sometimes occur even in summer. Older people who have not been immunized the previous flu season should ask their physician about flu vaccinations. They add no value for people who had been previously immunized.

Preventing Skin Disorders

An estimated 3% to 10% of travelers experience some skin problem related to their trip, particularly when traveling to tropical and subtropical areas.

Avoiding Exposure to Sunlight. Many developing countries are in the tropics were sunlight is intense. Ultraviolet radiation from sunlight not only can cause sunburn but excessive sunlight and heat can cause toxic skin reactions in susceptible individuals. Everyone should avoid episodes of excessive sun exposure, particularly during the hours of 10 AM to 4 PM, when sunlight pours down 80% of its daily dose of damaging ultraviolet radiation. Reflective surfaces like water, sand, concrete, and white-painted areas should be avoided. Clouds and haze are not protective. High altitudes increase the risk for burning in shorter time compared to sea level and lower altitudes. Sunscreens and sunblocks used generously are important, but they should not be relied on for complete protection. Wearing sun-protective clothing is equally important and protects even better than sunscreens. Everyone, including children, should wear hats with wide brims.

Preventing Skin Infections. People who visit the tropics or developing regions are at risk for a number of skin disorders, including fungal and other infections. Cleanliness is essential. Bathing or showering is very beneficial, but if there are no facilities, simply washing with soap and water (even if cold) is still helpful. (Note: taking multiple daily showers can remove protective oils and is not recommended.)

The skin should also be kept dry in order to prevent fungal infections, which thrive in damp, warm climates. Take special care to clean and keep dry certain skin areas where infections are most likely to occur. They include creases in the skin, the armpits, the groin, buttocks, and areas between the toes. Use talcum powder in these areas. Keep socks dry.

Precautions when Traveling to High Altitudes

Acute high altitude illness, or mountain sickness, can effect the brain (mountain sickness, cerebral edema) or the lungs (pulmonary edema) or both. Studies suggest that about one-quarter of climbers experienced symptoms at 7,000 to 9,000 feet and 42% of them have symptoms at 10,000 feet. In most cases the condition is mild. Severe lack of oxygen at high altitudes, however, can cause serious problems in some people.

• Acute Mountain Sickness. This syndrome is defined as headache and at least one other relevant symptom when a person climbs to about 8,000 feet. Other symptoms include upset stomach, dizziness, weakness, fatigue, and difficulty sleeping. It typically develops between six and 10 hours after ascent but some people experience them as early as an hour after a climb.
• High Altitude Cerebral Edema (HACE). HACE is a life-threatening brain swelling and the severe endpoint of acute mountain sickness. Symptoms include altered consciousness and loss of coordination. In extreme cases, it can lead to coma and death.
• High Altitude Pulmonary Edema (HAPE). HAPE is fluid in the lungs that in rare cases can be severe. In one study, about 75% of mountain climbers who went to 15,000 feet had some mild form of HAPE. Worse performance and a dry cough suggest the onset of HAPE. In extreme cases it can cause severe lung deterioration. (If it is going to develop at all, HAPE usually occurs in the first two days and rarely after four days at a given altitude.)

Luckily, symptoms of the more severe complications come on slowly, are easily recognized, and resolve when returning to a lower altitude.

Risk Factors for High Altitude Sickness. The risk for high altitude sickness is determined by certain characteristics: the rate at which a person ascends; the altitude reaches; altitude during sleep; and individual physiology. People who live yearlong at low altitudes are much more likely to be ill at greater heights.

Being physically stronger is not protective. And certain common conditions (heart disease, diabetes, hypertension, mild emphysema, and pregnancy) play no role in a person's risk for high altitude sickness. (Upper respiratory infections, however, do increase the risk for HAPE.)

Precautions against Mountain Sickness. A reassuring study found that older people, even those with heart disease, can usually exercise safely at higher altitudes. They are advised, however, to take it easy for a few days at higher levels until they can adjust to the altitude. Those taking medication to combat hypertension should consult a physician about increasing dosage if traveling to high altitudes. And anyone with a chronic medical condition should check with his or her doctor.

The following are some measures for preventing mountain sickness.

• As a rule, ascend no more than 1,000 feet per day at altitudes of 8,000 feet and above. Drink six to eight glasses of water or juice a day and avoid alcohol.
• Stop climbing when experiencing any symptoms of acute mountain sickness. Descend if symptoms worsen. Also descend immediately if there are any symptoms of HACE or HAPE.
• Supplementary oxygen may be required for people who show signs of these conditions.
• People who are hiking to very high altitudes may consider an inflatable chamber (Gamow bag and others). Such devices enclose a person, and when pumped up they simulate air pressure found at low altitudes.

Medications Preventing and Managing Mountain Sickness. Some medications are available for prevention or treatment of acute mountain sickness.

• Ibuprofen (Advil) may be sufficient to manage headache associated with acute mountain sickness.
• Acetazolamide (Ak-Zol, Diamox) taken one day before, and continued during initial exposure to high altitude, can reduce symptoms of acute mountain sickness, improve exercise performance and sleep, and reduce muscle and body fat loss. It may be used to treat minor symptoms of acute mountain sickness, but if symptoms persist, the trekker should descend.
• Dexamethasone (Decadron Phosphate, Dexasone, Hexadrol Phosphate) is used to treat acute mountain sickness and cerebral edema (HACE). Dexamethasone is not recommended for prevention, however, because of potentially dangerous side effects.
• Nifedipine (Adalat) is used to treat pulmonary edema (HAPE) and may be used for prevention in people who know they are at high risk for HAPE.
• Preventive use of salmeterol (Serevent), a long-acting inhaled asthma drug known as a beta-adrenergic agonist, may reduce the risk for HAPE by over 50%.

Precautions for Divers

Travelers planning to descend rather than ascend must also take precautions. Individuals with the following conditions should not scuba dive:

• Heart and lung problems.
• Bleeding disorders.
• Chronic ear infections.
• Insulin-dependent diabetes.
• Pregnancy.
• History of seizures.
• History of migraine headaches. Diving, in fact, is becoming known as a cause of many types of headaches, and anyone with a history of chronic or frequent headaches should discuss these issues with a health professional familiar with this sport.

Avoiding Air Embolism. Air embolisms are bubbles that obstruct blood vessels and can occur in divers who hold their breath while swimming up to the surface. They can be life threatening and cause long-term neurologic impairment, including memory lapses, impaired thinking, and emotional disorders. Even tiny bubbles may do some harm over time. One study found that in amateur divers who dive frequently, tiny bubbles appeared to increase the risk for small brain lesions and degenerating spinal disks.

To eliminate these bubbles, experts advise the following:

• Ascending no faster than 30 feet per minute.
• Remain 15 feet below the surface for three to five minutes before surfacing.

Those who do scuba dive should avoid air travel for 24 hours after diving.

Drowning. The other major cause of scuba diving deaths is drowning in underwater caves due to improper training and poor equipment.