Arthropods are not only a source of nuisance and pain at the site of their bites, but they also may cause more harmful generalized reactions as a result of venom production or allergies to substances that are injected at the time of the bite. Moreover, arthropods can transmit serious, potentially life-threatening diseases, including malaria, yellow fever, dengue hemorrhagic fever, filariasis (mosquitoes); viral encephalitides (mosquitoes, ticks); onchocerciasis (black flies); leishmaniasis (sand flies); African trypanosomiasis (tsetse flies); American trypanosomiasis or Chagas disease (reduvid or kissing bug); plague and tungiasis (fleas); typhus (fleas, lice, ticks); and relapsing fever (lice and ticks). For details, see the American Academy of Pediatrics Red Book or the American Public Health Association Communicable Diseases Manual.
Each of the arthropod vectors and injury-producing organisms may be found in a particular geographic range. Whereas vaccines are available to protect individuals against some of these illnesses (yellow fever, plague, tick-borne encephalitis, Japanese encephalitis), and antimicrobial prophylaxis may help to avert others (malaria, typhus), avoidance of exposure to the arthropod whenever possible is the primary means of preventing infection.
The following recommendations will help the traveler limit exposure to flying and nonflying arthropods:
Minimize evening walks in the countryside. Wear light-colored, long-sleeved shirts and long pants, particularly in the evening.
Wear footwear at all times and always shake before putting it on (scorpions particularly like dark, warm places; they do not want to deal with humans but will if cornered or threatened)
Use insect repellant on exposed areas of the body and clothing. Choose an insecticide containing 25%-30% DEET (N,N-diethyl-m-toluamide or N,N-diethly-3-methylbenzamide) for exposed skin and permethrin products for clothing, bed nets, and camping gear. Repellent efficacy and duration vary considerably among products and among mosquito species, and are markedly affected by ambient temperature, amount of perspiration, exposure to water, abrasive removal, and other factors.
Sleep in air-conditioned or well-screened rooms or under bed nets in areas where arthropod-borne diseases are present.
Prior to sleep, spray room/net with an "anti-fly" spray that contains permethrin or pyrethrum to kill mosquitoes that may be present and smaller bugs that may penetrate the netting.
Use intact mosquito nets that do not contain holes and which are well tucked in around beds at night.
Avoid perfumes and scented creams, soaps, or aftershave especially in the evening.
Patients visiting countries with malaria risk should take prophylactic medication. Which of the following regimes is recommended depends on the plasmodia and resistance patterns in the area of travel. Check the CDC for recommendations. (Table 1)
Table 1. Recommended Medications and Regimes for Malaria
|Prophylactic Medication||Recommended Regimes|
|Chloroquine phosphate (Aralen®)||Dose is weight based. Should be taken weekly from 1 week prior to exposure until 4 weeks after exposure on the same day each week. Side effects are rare and include dizziness, headache, nausea, and vomiting. May cause an acute exacerbation of psoriasis. The drug should be discontinued if visual changes occur.|
|Doxycycline hyclate (many brand names)||Should be taken once daily from 2 days before exposure until 4 weeks after exposure. May cause rashes and an intense burn with exposure to sun (use extra sunscreen) and vaginitis in women (bring antifungal vaginal cream). Do not take with milk products or antacids. Contraindicated in children less than 8 years of age and women who are pregnant or breastfeeding.|
|Malarone® (fixed dose of atovaquone and proguanil hydrochloride)||Available as adult or pediatric tablets. Pediatric dose is weight based. Should be taken daily from 2 days before exposure until 7 days after departure from the malaria area. Should be taken the same time every day with food or milk. Side effects are uncommon but include severe or uncontrolled vomiting, diarrhea, fever, nausea, stomach pain, loss of appetite, dark urine, clay-colored stools, jaundice, or mouth sores. Contraindicated in renal failure and not recommended for children under 5 kg, and pregnant or breastfeeding women. Use caution in patients with liver disease.|
|Mefloquine (Lariam®)||Should be taken once weekly from 2 weeks before until 4 weeks after exposure. Tablets should be taken with food and at least 8 oz of potable or safe water. Side effects include dizziness, vomiting, anxiety, restlessness, and extra systoles. May exacerbate already existing psychiatric disturbances and depression. May interfere with some seizure and cardiac drugs. Contraindicated in major psychiatric disorders, seizure disorders, and cardiac conduction problems.|
|Primaquine||Should be taken daily from 2 days before until 7 days after exposure. Contraindicated in G6PD (glucose-6-phosphate dehydrogenase) deficiency, pregnancy, and breastfeeding. All persons who take primaquine should have a documented normal G6PD level before starting the medication. It is only for short-term use in areas where Plasmodium vivax is the predominant malaria parasite.|
Diarrhea is a frequent problem for Americans traveling abroad. Typically, diarrhea lasts less than 96 hours and responds to rehydration alone. The following recommendations will help prevent diarrhea occurrence and minimize its effects should it develop.
To prevent diarrhea, avoid water and insufficiently cooked foods, which can harbor the organisms that cause diarrhea. Avoid food (other than commercially processed bread) that isn't boiled, steaming hot, washed, and peeled by the patient. Avoid food from street vendors. This is the mainstay of preventing travelers' diarrhea. Ice, unless made with safe water as indicated below, should not be taken in drinks.
Safe beverages include:
Boiled water beverages -- tea or coffee (if a film is present on the surface of the liquid, it probably was not fully boiled);
Carbonated bottled drinks (keep in mind that large intake of mineral water can cause mild diarrhea from the cathartic effect of the minerals);
Canned/boxed fruit juices; and
Bottled/canned alcohol containing beverages -- beer or wine in moderation.
Recommendations for water treatment include the following:
Heat water until vigorous boiling is achieved.
Use iodine tablets as directed. Use 5 drops of tincture of iodine (also useful for treating cuts and scrapes) per liter of water and wait 30 minutes. Pregnant women should use iodine cautiously to avoid interfering with fetal thyroid development.
Use chlorine dioxide tablets as directed. The amount of liquid chlorine bleach to use depends on the chlorine concentration -- 10 drops of 1% bleach, 2 drops of 4%-6% bleach, or 1 drop of 7%-10% bleach per liter of water.
Use a portable filter (filter size less than 0.4µm), available at sporting goods stores or in their product catalogues or online. Several versions of portable UV light sources are available, including liter water bottles with UV light or filters built in.
Prophylaxis with antibiotics can cause serious problems from toxicity and antimicrobial resistance. Pepto-Bismol® taken as 2 tablets, 4 times daily for short periods has been shown to reduce the incidence of travelers' diarrhea. If aspirin allergy exists, or if the patient is already on large aspirin doses or is on warfarin, Pepto-Bismol (a salicylate) is contraindicated.
Treatment for diarrhea is first and foremost fluid replacement to prevent dehydration. Oral rehydration or Gatorade® packets can be mixed in juice or other safe liquid. Advise patients not to use milk, alcohol, tea, or coffee. Simple foods that do not usually aggravate gastrointestinal upset include bread, rice, bananas, and apples. Spicy or fatty foods should be avoided.
Pepto-Bismol, if it is not contraindicated, may help to alleviate nausea, cramping, and diarrhea by binding to toxins that cause the illness. For treatment of diarrhea, 2-4 tablets are taken every 30 minutes, for a maximum of 8 doses. Pepto-Bismol often turns the tongue and stools black during use. This is of no clinical importance.
Imodium® or Lomotil® may reduce the cramping and number of stools associated with travelers' diarrhea. These agents do not stop the process causing the diarrhea, may mask dangerous pooling of fluid in the intestinal tract, and prevent the elimination of dangerous toxins and bacteria. However, either is useful for patients who must travel with unresolved diarrhea. Neither should be used by children and pregnant or breastfeeding women. Adults should stop taking these agents if any of the following signs are present: fever, chills, severe cramping, abdominal bloating, blood in the stool, diarrhea lasting more than 2 days, jaundice, or vomiting of more than 6-12 hours in duration. Both agents can cause tiredness, dry mouth, restlessness, confusion, or allergic reactions, particularly in the elderly. Lomotil is available only by prescription.
Medical help is needed if the diarrhea is very severe or persists for more than 2 days despite appropriate self-medication. If medical care is available, consider antibiotics (Table 2). However, the antibiotics commonly used for this purpose can also cause some serious side effects, including antibiotic resistance and overgrowth of Clostridium difficile.
Table 2. Antibiotics and Recommended Regimes for Diarrhea
|Antibiotics for Diarrhea||Recommended Regimes|
|Doxycycline hyclate (many brand names)||One tablet every 12 hours for 3-5 days, taken with meals. May cause rashes and an intense burn with exposure to sun (use extra sunscreen) and vaginitis in women (bring antifungal vaginal cream). Do not take with milk products or antacids. Contraindicated in children less than 10 years of age and pregnant or breastfeeding women.|
|Trimethoprim and sulfamethoxazole (Bactrim®, Septra®)||One double-strength or 2 single-strength tablets twice daily for 3-5 days. Discontinue if itching, mouth blisters, or skin rash develops. Contraindicated in third trimester of pregnancy, sulfa allergy, anemia, kidney disease, or G6PD (glucose-6-phosphate dehydrogenase) deficiency.|
|Fluoroquinolones (norfloxacin [Noroxin®], ciprofloxacin [Cipro®])||One tablet twice daily for 3-5 days. May cause sleeplessness, allergic reactions, or tendon problems. Contraindicated in pregnant or breastfeeding women and children less than 18 years of age.|
Vaccines administered to people traveling abroad are generally safe (Table 3). Reactions consisting of pain, redness, and swelling at the site of the injection are not uncommon and resolve in 48 hours or less. Some people may experience low-grade fevers, headache, and malaise after certain vaccines. Permanent consequences are rare. If more severe reactions are experienced, however, patients should seek urgent medical care. Acetaminophen or aspirin is usually sufficient for relief. Specific contraindications are noted with the vaccine, but any hypersensitive reaction to previous vaccine doses, allergy to vaccine components, or severe acute illness are always reasons not to give vaccines.
Contraindications to immunizations during pregnancy may be relative to the risk. Contraindications during breastfeeding are related to the contraindications for giving the vaccine to children. Patients who are immunocompromised generally should not receive live agent vaccines. Recent blood transfusion may be a temporary contraindication to certain vaccines. No vaccine is 100% effective so all other preventive measures discussed above should be used at all times. Patients need to plan to receive vaccinations well before they travel -- 1-2 months is often needed -- so that all regimens can be completed before leaving home and prior to exposure. A card listing all vaccines administered should be issued upon completion.
Table 3. Vaccine-Specific Recommendations
|Vaccine||Dose and Contraindications|
|Cholera||No longer available in the United States. Diarrhea precautions should be followed.|
|Hepatitis A||Inactivated vaccine, 2 doses given intramuscularly (IM), 6-18 months apart. If time is insufficient, 1 dose is often enough to provide 6 months' protection. If vaccination is refused or contraindicated, a single dose of immune globulin (0.02 mL/kg) provides up to 3 months of protection. Contraindications include pregnancy and less than 1 year of age.|
|Hepatitis B||Three doses given IM at 0, 1, and 6 months. Many people develop some protection after the first dose should the entire series not be finished before travel. The combined hepatitis A/hepatitis B vaccine (Twinrix®) is available for those travelers needing protection against both diseases. Three doses are given at 0, 1, and 6 months. The first 2 doses are necessary prior to travel. Contraindications include allergy to baker's yeast.|
|Influenza||One dose yearly. Contraindications include egg allergy.|
|Japanese encephalitis virus (JEV)||Two inactivated JE vaccines are available for long-term travelers, recurrent travelers, or expatriates who will be in urban areas but will likely visit endemic rural or agricultural areas during a high-risk period of JEV transmission. This is a mosquito-borne disease, and the preventive measures for avoiding mosquito bites are sufficient for most travelers. JE vaccine is not recommended for short-term travelers whose visit will be restricted to urban areas or times outside of a well-defined JEV transmission season. JE-Vax®, for patients 2-17 years of age is given as 3 doses at 0, 7, and 30 days and should be completed at least 10 days before exposure. Contraindicated in anyone who is highly allergic to more than 1 or 2 substances.
Ixiaro® (available since 2009) is for use in persons older than 17 years of age. It is given as a 2-dose series at 0 and 28 days, and the series should be completed 7 days before exposure. If the traveler who received Ixiaro remains at risk after 1 year, a booster should be given. No data are available on pregnancy risk for either vaccine.
|Measles (usually available as combined measles, mumps, and rubella or MMR vaccine)||Live virus vaccine given as 1 dose IM to anyone born after 1957 (no matter where they are traveling) who received only 1 dose previously. Consider administration for anyone born before 1957 who is not immune and who will be at a very high risk for exposure. Vaccine side effects for this age group have not been well studied. Contraindications include altered immune system and anaphylactic response to eggs or neomycin.|
|Meningococcus||Two vaccines are available, both of which give protection against types A, C, Y, and W135 of Neisseria meningitides. Both are given as a single dose IM with a booster in 3-5 years (check requirements of Saudi Arabia for people traveling to Hajj). The vaccine is particularly recommended for patients who have functional or anatomic asplenia and terminal complement deficiency. The MPSV4 (meningococcal polysaccharide vaccine) is a polysaccharide vaccine for pregnant patients and those over 55 years of age. The MCV4 (meningococcal vaccine) is a conjugate vaccine for patients less than 55 years of age. Contraindications include a history of Guillain-Barré syndrome.|
|Pneumococcus||PPSV23 (23-valent pneumococcal polysaccharide vaccine) is a polysaccharide vaccine containing the 23 most common types of Streptococcus pneumoniae. It is given as a single IM dose. A second dose of PPSV23 may be recommended for those with heart, lung, or liver disease, sickle cell anemia, diabetes, cochlear implant, or who are not immunocompetent, because they are at particular risk for complications from pneumococcal illness.|
|Poliomyelitis||Inactivated and live polio vaccines are available. The inactivated form is used in the United States. For primary vaccination, the schedule for the inactivated vaccine is 3 doses, -2 months apart with a booster at -12 months and then 4-6 years later. For adults previously vaccinated with either oral or inactivated polio vaccine, a booster is recommended when traveling to high-risk areas.|
|Tetanus-diphtheria-pertussis||Available as DTaP (diphtheria, tetanus, and pertussis) for children under 7 years of age, Tdap (tetanus, diphtheria, and pertussis) for those 7-65 years of age and not pregnant. DT (diphtheria and tetanus) for children under 7 years of age and Td (tetanus and diphtheria) for those over 7 years of age is available for those in whom pertussis vaccine is contraindicated. Initial series is 3 doses at 2-month intervals and a booster 12 months later for children up to 7 years of age, and 2 doses in a 2-month interval plus booster 12 months later for those over 7 years of age. All are administered IM. Boosters should be given every 10 years thereafter for all ages. Td is not contraindicated for use during pregnancy. Tdap should be considered for all adults, including pregnant women who are at high risk for exposure to pertussis or if Td is not available.|
|Typhoid||Two vaccines are available, neither of which has been extensively studied for efficacy in travelers. It should be considered for patients traveling to highly endemic areas or who are living with a chronic typhoid carrier. Typhim Vi®, a capsular polysaccharide vaccine, appears to be the most protective. It is given as a single parenteral dose followed by boosters every 2 years if needed. Vivotif Berna® (Ty21a) is a live bacteria vaccine given orally as 1 capsule every other day for 4 doses with boosters every 5 years. It is taken 30 minutes before eating and must be refrigerated. It is contraindicated in patients who are on antibiotics, lactose intolerant, less than 6 years of age, pregnant, breastfeeding, or who are immunocompromised. Ty21a should not be used if traveler is taking antibiotics, including malaria prophylaxis.|
|Yellow fever||A live virus vaccine that must be administered at an official center and patients must obtain an international certificate of the vaccination or prophylaxis with the official stamp. Most travelers can avoid yellow fever by observing mosquito precautions, but international health regulations, which respect country needs to avoid importation of the virus and control outbreaks, are different from CDC and ACIP recommendations for use. It is given as a single subcutaneous dose at least 10 days before entry into the area where it is required. Boosters are given every 10 years. Rate of serious complications is higher in persons who are over 60 years of age given a first dose ever of vaccine. Contraindicated in infants less than 9 months of age, breastfeeding women, patients with thymus disorders including absence, and all other immunocompromised states. Your state health department can provide a list of approved yellow fever vaccination sites and an application to become a site if you wish to administer the vaccine in your practice.|