Dr. Laufer is assistant professor of pediatrics, division of infectious diseases and tropical pediatrics at the Center for
Vaccine Development, University of Maryland School of Medicine, Baltimore. She has nothing to disclose in regard to affiliations
with, or financial interests in, any organization that may have an interest in any part of this article.
Preparing children to travel with their families to a developing country requires special attention. The first part of this
article (February 2006) reviewed the needs of groups with particular concerns (adolescents, children with a disability, children
with a chronic disease) and discussed preparation for the journey itself, general safety concerns, and protecting children
against gastrointestinal infection and insects. In this part, I review immunizations, prophylaxis against malaria, management
of traveler's diarrhea, and services provided by local travel clinics.
A check on standard immunizations
A pretravel visit is an excellent opportunity to review your patient's vaccination history. Infections that have been almost
completely eliminated in the US—such as measles, polio, and Haemophilus influenzae type B—continue to cause childhood illness abroad. Recently, unvaccinated Americans traveling abroad have contracted measles
and diphtheria.1,2 For parents who have previously been reluctant to fully vaccinate their children, the significant risk of acquiring vaccine-preventable
infection abroad makes complete vaccination before travel imperative.
Young children who have not completed the primary vaccine series should be immunized according to the accelerated vaccination
schedule to maximize protection before they travel. In general, this means that the primary series can be started at 6 weeks
of age and subsequent doses given at four-week intervals. The catch-up schedule, which provides information about the minimum
age and interval for all routine childhood vaccinations, is available on the National Immunization Program Web site www.cdc.gov/nip/recs/child-schedule.htm or in The Red Book.3
Infants 6 to 12 months of age who are traveling to a developing country should be vaccinated against measles with either a
monovalent measles vaccine or the standard MMR. Children who receive measles vaccine before 12 months still require two doses
of MMR after 1 year of age. If a child has received one dose, the second dose can be administered after more than one month
has elapsed.
Tetanus immunization should be updated every five years for travelers. A single booster dose of inactivated poliovirus vaccine
(IPV) is recommended for adults who are traveling to a region where cases of polio are known to occur. You may also consider
giving a booster dose to teenagers, whose immunity may be waning. As of September 2005, endemic polio cases had occurred in
India, Pakistan, Afghanistan, Nigeria, and Niger, although imported disease has spread to many surrounding countries and has
even reached Indonesia.
Parents who are moving to a developing country may ask about vaccinating their children overseas. Although some vaccines are
available abroad, the full spectrum—including new vaccines, such as the conjugated polyvalent pneumococcal vaccine, and even
not-so-new ones, such as H influenzae type B and hepatitis B vaccines—may not be available. Moreover, in developing countries, maintaining the cold chain to preserve
vaccine potency can be challenging. Adults and children should be advised to obtain as many vaccinations as possible in the
US or other developed countries. If vaccines are administered abroad, parents should investigate the reliability of the source.
Hepatitis A vaccine
Hepatitis A is the most common vaccine-preventable disease acquired abroad. The incidence is three to 20 infections for every
1,000 person-months of travel.4 Children often have asymptomatic hepatitis A infection but can be an important reservoir for transmission for several months.
Table 1: Vaccines for international travelers
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Hepatitis A is spread by the fecal-oral route without any known intermediate reservoir. Hand washing and avoiding contaminated
food should therefore decrease the risk of exposure to the virus. In addition, highly effective and well-tolerated vaccines
are available to prevent infection (Table 1). Travelers to countries with a high incidence of hepatitis A—which include most
countries outside the United States, Canada, Western Europe, and Australia—should be vaccinated against the virus.
The vaccine is approved for children older than 1 year. Although two doses, separated by at least six months, confer long-term
protection, a single dose protects travelers within two to four weeks of administration. For children who are too young to
be vaccinated or who are traveling to a high-risk region within two weeks, pooled immune globulin can be given by intramuscular
injection.
Typhoid fever immunization
Infection with Salmonella typhi can result in typhoid fever, which can cause life-threatening intestinal hemorrhage and perforation. Like hepatitis A, typhoid
fever is spread by the fecal-oral route. Vaccination against the disease has become even more important recently because the
causative organism in some regions of the world has developed resistance to many antibiotics, including fluoroquinolones.5
Two types of vaccine are available: Ty21a, the live attenuated oral vaccine that is approved for children older than 6 years,
and ViCPS, a parenteral capsular polysaccharide vaccine for children 2 years and older.
Protection against rabies
Advising families about vaccination against rabies is complex because you must weigh the high cost and multiple doses required
against the almost 100% mortality caused by the disease. Even a minor animal bite or scratch in a tropical country is a medical
emergency. After exposure to a potentially rabid animal, the traveler should seek medical care immediately for thorough cleaning
of the exposed area and administration of rabies vaccine and rabies immune globulin within 48 hours. Travelers who have been
vaccinated against rabies require only an additional two doses of vaccine and do not need to receive immune globulin.
Because rabies immune globulin is often unavailable in remote areas, vaccination against rabies has generally been recommended
to travelers planning to visit such areas for longer than 30 days when exposure to rabid animals is a possibility. Children
are at greater risk than other travelers. They may not be able to report an exposure, so parents may not know that the child
requires immediate treatment. Also, when attacked by an animal, children are more likely to be bitten on the head and neck,
locations more likely to lead to disease.6,7 Rabies vaccination is expensive; if every family member cannot be vaccinated, younger children should be given priority.
When administering the rabies vaccine, keep in mind the following cautions:
- available vaccines often cause local reactions, such as pain and erythema at the injection site; mild systemic symptoms are
common
- chloroquine and probably mefloquine can interfere with the efficacy of rabies vaccine, so the vaccination series should be
completed before starting antimalaria prophylaxis
- travelers who have been vaccinated previously and are returning to a high-risk area should have their serum titer checked
every two years after vaccination.
Other vaccines
Additional vaccines that may be given to international travelers are listed in Table 1. Many of them have special warnings
and indications for children. Yellow fever vaccine is the only one that may be required for international travel, in particular
travel from a country with yellow fever to a neighboring region. The Centers for Disease Control and Prevention (CDC) has
a Yellow Fever Hotline for further information: 404-332-4559. Never give the vaccine to children younger than 4 months because
of the higher occurrence of vaccine-associated encephalitis in this age group.
Vaccination against Japanese encephalitis is usually recommended only for people traveling to an endemic region for a long
period and who will be living in a rural area. The vaccine against Neisseria meningitidis currently includes serotypes A, C, Y and W-135. It is recommended for travelers to "the meningitis belt" from Senegal to
Ethiopia in Africa, especially during the dry season, and to any other areas with active outbreaks that are reported on the
CDC and World Health Organization Web sites listed in the first part of this article (February 2006). Although the polysaccharide vaccine is recommended for children older than 2 years, children as young as
3 months have been shown to have some response to serotype A, so the vaccine may benefit infants traveling to an area of high
prevalence. The conjugate vaccine should be used for children older than 11 years.8
Malaria prophylaxis
As with diarrheal disease, the first step in preventing malaria is to avoiding contact with the causative organisms. Prophylaxis
should not take the place of protective measures—including wearing clothing that covers the arms and legs and using bed nets,
screens, and N, N-diethyl-3-methylbenzamide (DEET)—because prophylaxis may fail, compliance may be poor, and insect bites
may cause vector-borne infections other than malaria, as well as secondary skin infections.
Chloroquine was the first medication used for malaria prophylaxis. Because of widespread resistance to the drug, its efficacy
is now limited to areas north of the Panama Canal in Central America. Mefloquine is generally recommended for children of
any age who are traveling to areas with chloroquine-resistant malaria.
Mefloquine should be not be given to any child with psychiatric disease (although it is considered safe for a child with attention
deficit hyperactivity disorder), a seizure disorder, or cardiac conduction disturbance. Although adolescents and adults taking
mefloquine report neuropsychiatric symptoms, such as vivid dreams and a nonspecific sense of "feeling odd," such complaints
appear to be less common in children and the medication is generally well tolerated.
Both mefloquine and chloroquine should be administered with a sweet food to hide the bitter taste. Options include mixing
the medication with chocolate syrup, condensed milk, or fruit jam or placing it in a sandwich cookie.
Another choice for malaria prophylaxis is atovaquone-proguanil, which has a pediatric formulation that is approved for children
who weigh 5 kg or more. Although it is expensive and requires daily administration, the medication has fewer neuropsychiatric
side effects, a less bitter taste, and a shorter course of therapy before and after travel than chloroquine and mefloquine.
Atovaquone-proguanil is taken one day before arrival in an area of malaria transmission and daily thereafter until seven days
after leaving the area. In contrast, prophylaxis with chloroquine and mefloquine begins two weeks before travel and continues
for four weeks afterward. If price is not a concern, atovaquone-proguanil is generally preferred over mefloquine for older
children and adults because of the more favorable side-effect profile, which can improve compliance.
Doxycycline is effective against multi-drug-resistant malaria but can only be given to children older than 8 years and can
cause skin photosensitivity and lead to Candida infections of the mucosa. Primaquine has recently been proposed as an alternative prophylactic medication against malaria
among short-term travelers; it is often used for terminal prophylaxis in travelers who may have latent infection with Plasmodium ovale or Plasmodium vivax. Check glucose-6-phosphate dehydrogenase (G6PD) activity before giving primaquine because administration can lead to severe
hemolyisis among G6PD-deficient patients.
Table 2: Drugs for malaria prophylaxis
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Table 2 lists information about age restrictions, dosage, and formulation for the medications most often prescribed for malaria
prophylaxis. For a thorough review of prophylaxis in children, see "Traveling with infants and children" by Stauffer and colleagues.9Travelers who develop malaria while abroad should continue antimalaria prophylaxis after the treatment course is complete
because an episode of malaria does not confer immunity. Patients taking mefloquine for prophylaxis should not receive halofantrine
to treat a possible malaria episode because of the risk of cardiac arrhythmia.10
Managing traveler's diarrhea
Diarrhea is such a common complication of travel that it has earned nicknames throughout the world: Montezuma's revenge, Delhi
belly, and Tut's tummy, to name a few. Although diarrhea is mostly an inconvenience, dehydration is a significant concern,
especially in young children, who develop traveler's diarrhea more often than adults and have more prolonged symptoms.11 The same basic principles of outpatient therapy for diarrhea hold true for children who are abroad as for those at home.
Oral rehydration therapy (ORT) is the mainstay of managing mild and moderate dehydration. ORT packets can be brought from
home but are also available in most pharmacies throughout the world. The contents of the ORT packet should be mixed with clean
water. If the child is not dehydrated, feeding should continue, and ORT can be used to replace losses if the parent thinks
that normal intake is inadequate.
If the child becomes dehydrated, he should receive ORT first and then start feeding; this method has been shown to shorten
the duration of diarrhea, compared to giving fluids alone.12 Most enteric infections associated with traveler's diarrhea do not cause severe vomiting, so dehydration requiring intravenous
fluids can usually be avoided by keeping up with losses orally.
Unlike diarrhea in the US or other industrialized countries, traveler's diarrhea is often bacterial in origin.13 Although the infectious organism is usually never identified, pathogens most commonly associated with traveler's diarrhea
are enterotoxigenic Escherichia coli, Shigella, and Campylobacter. Ciprofloxacin, 20 to 30 mg/kg/day, divided bid for three days, and other fluoroquinolones are the medications most often
prescribed to treat traveler's diarrhea empirically in adults, but these medications are not licensed for children younger
than 18 years. Because of resistance worldwide of enteric pathogens to trimethoprim-sulfamethoxazole, azithromycin is an
option for treating children with traveler's diarrhea, even though it is not indicated by the Food and Drug Administration
in this setting. Azithromycin is given at a dosage of 10 mg/kg/day for three days, although there is evidence that a single
dose may be sufficient.14 If the child does not improve after empiric therapy or has high fever, chills, blood in the stools, persistent vomiting,
or a change in mental status, he should be brought for medical attention immediately.
Bismuth subsalicylates and loperamide can be used to treat adolescents and adults who have two to six stools a day and no
other signs of invasive infection, such as blood in the stool or fever. The American Academy of Pediatrics recommends against
giving antimotility agents to children because of conflicting data regarding the efficacy of these agents and concerns about
their neurologic effects. The salicylic acid in bismuth subsalicylates poses a theoretical risk of Reye syndrome, although
no association has ever been documented.
Bismuth subsalicylates have been studied more extensively as prophylactic agents than agents to control diarrhea. To prevent
diarrhea, they must be taken four times a day, which is a significant challenge to adherence in pediatric patients.
Your local travel clinic
As is clear from this review, advising families who are planning to travel to less developed countries is a large undertaking.
Travel medicine specialists at travel clinics have experience in giving advice, instructions, and recommendations to travelers
and usually offer extensive written material to reinforce their discussions with clients. Physicians who specialize in travel
medicine have access to up-to-date and detailed information about health risks at specific destinations and are familiar with
the advantages, disadvantages, and side effects of malaria prophylaxis and other pre-travel interventions. The travel clinic
can also help to identify reliable local hospitals or health-care providers at the destination.
Travel clinics have most travel-related vaccines in stock and can give them at the time of the first appointment. The only
vaccination required to travel to some countries in South America and Africa, the yellow fever vaccine, must be administered
at a recognized site, and administration must be recorded on a WHO vaccination record card.
You can find information about travel clinics in your area by visiting the Web site of the American Society for Tropical Medicine
and Hygiene: www.astmh.org/scripts/clinindex.asp. The site indicates whether the clinic's health-care providers are certified by the International Society of Travel Medicine.
If possible, meet with the family before their appointment at the travel clinic to prepare them for the visit and identify
any factors that may complicate travel. Remind the family to inform the clinic staff of any medications that family members
are taking and any allergies or other underlying medical conditions. You might even consider providing a referral letter,
especially if health concerns are complex. You can help parents make a list of questions before the visit. For a list of suggested
questions, see the Guide for Parents.
Protecting ideal travelers
Children benefit immensely from travel to new and different places. They are ideal travelers because of their natural curiosity
and open mind. You can enhance the family travel experience by providing sound, practical advice to keep children happy and
healthy during their adventures.
Acknowledgment
Chandy John, MD, assisted in the preparation of the manuscript of this article.
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