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Presentations at the 49th Annual Meeting of the American Society of Tropical Medicine and Hygiene, Houston, Texas, Oct/Nov 2000
By Philip R. Fischer, MD, DTM&H
At work as at home, children often seem to stimulate controversy. During the 49th Annual Meeting of the American Society of Tropical Medicine and Hygiene in Houston, Texas, conference participants overloaded a large meeting room to hear a discussion of "Controversies in Pediatric Travel Medicine." With chairs full, some participants sat on the floor while others stood. Three expert speakers guided participants through consideration of the pediatric aspects of malaria prevention, air travel and altitude, and diarrhea management.
Sheila Mackell, a pediatrician who cares for travelers within the Kaiser Permanente system in northern California, reminded conference goers about the proper use of clothes, nets, and permethrin to avoid mosquito bites. She then reviewed the history of the diethyltoluamide (DEET) controversy.
For decades, DEET has been used for millions of children with few side effects. In fact, it is estimated that approximately 30% of the population of the United States uses DEET each year. Among the millions who use DEET, 14 serious adverse reactions have been reported, and 13 of these were in children. There are, however, no data clearly linking the concentration of DEET to the risk of poor outcomes. The U.S. Environmental Protection Agency (EPA) rescinded their safety limits for the use of DEET in children a few years ago; the EPA now suggests only that DEET be used carefully (not on hands and only on exposed skin rather than under clothes).1 Nonetheless, some pediatricians still suggest that children in the United States not use DEET during the first year of life and that they not use DEET in concentrations greater than 10%. Reviewing the data as well as the recommendations, Dr. Mackell found no evidence to suggest that pediatric use of DEET be limited in concentration or by age.
A seizure disorder is generally considered to be a contraindication to the use of mefloquine. What about mefloquine in children who have had febrile seizures? Febrile seizures occur in about 1% of children, and the great majority of these children do not subsequently have a persistent seizure disorder. Dr. Mackell, who lectures around the world on pediatric travel medicine, is not aware of any report of a mefloquine-related seizure in a child who had previously had a simple febrile seizure. Thus, mefloquine could likely be used safely in a child who only had a simple febrile seizure.
If, however, the seizure was recurrent, long lasting, or associated with other neurologic deficits, the child could actually have an underlying seizure disorder; in these cases, an alternative to mefloquine would be considered. Methylphenidate (Ritalin), like mefloquine, is postulated to lower a child’s seizure threshold. There is, however, no evidence of danger when using mefloquine and methylphenidate at the same time.
Adult travelers sometimes carry a "stand-by" curative dose of an antimalarial to use in the event of a febrile illness. For children, Dr. Mackell advised, a febrile illness should be cause to immediately seek medical attention. Stand-by therapy would only be advised in very rare situations when medical care is totally unavailable.
Karl Neumann, a pediatrician in New York who has been editing and writing travel medicine publications for years, then discussed issues relevant to children traveling in airplanes and at high altitude. He first considered the unborn child traveling by air. There is no evidence that fetal vital signs or fetal oxygenation are altered by travel in commercial aircraft. There might, however, be some concern about exposure to cosmic radiation. The exposure to cosmic rays is approximately 100 times higher at cruising altitudes than on the planet’s surface. Thus, 10 hours of flight would provide a similar amount of radiation exposure to one chest radiograph. This seems not to pose any clinically significant risk for routine travelers who are pregnant, but there is still some question about what this might mean for pregnant aircraft crew members who have more extensive exposure to atmospheric radiation.
Should recently born children fly in commercial airplanes? Despite some age limits that some people might arbitrarily impose, available evidence suggests that newborns may fly safely. Their lungs are adequately developed, and their oxygen dissociation curve and relative polycythemia (compared to adults) actually would help them in oxygen-restricted environments.
Is there a risk of sudden infant death syndrome (SIDS; also called "crib death" or "cot death") related to air travel? Dr. Neumann referred to a recent British Medical Journal article and subsequent discussion.2 Indeed, infants have lower oxygen saturation levels and more irregular breathing in atmospheres simulating an aircraft environment; there is not, however, any evidence that they are at increased risk of sudden death.
Dr. Neumann then went on to "debunk" some commonly held myths. He said that infants are not at particular risk of dehydration in airplanes. In fact, they do not even seem to be more irritable in planes than on the ground. The increase in intestinal air pressure (compared to the decreased aircraft ambient pressure) coupled with extra intragastric volumes of recent feedings might make children a bit more fussy. Thus, Dr. Neumann advises routine but not extra feedings for children in airplanes.
Can children with ear infections fly? Dr. Neumann surveyed more than 100 otorhinolaryngologists, and none had seen a case of ear problems related to air travel. In fact, most would not limit air travel because of a coincident ear infection. Similarly, there is no evidence that antihistamines and decongestants alter the incidence of earache with aircraft ascent or descent.
Should infants be restrained in airplanes? Again, this topic has stimulated much controversy, and Dr. Neumann noted that babies are the only on-board objects for whom restraint is not required during take-off and landing. There is anecdotal evidence that in-flight infant restraints might prevent one death or serious injury every two years. Car seats, however, are not designed to protect infants facing the sorts of impacts that occur during times of turbulence and crashes. There is also concern that mandated infant restraints in planes (with the resultant increases in cost) might actually prompt more children to travel by road rather than by air; this could be associated with more loss of infant life than would be prevented by such a measure. Thus, infant restraints (especially car seats) are not currently recommended for routine use in airplanes.
What about altitude sickness? A group of researchers in Denver, Colo., has studied altitude-related symptoms in preverbal children, and the incidence seems to be similar to that in older children and adults.3 Rate of ascent relates to the risk of mountain sickness, but age and fitness do not. There is some evidence that having an upper respiratory infection while ascending might increase the risk of a child developing high altitude pulmonary edema. Asthma is not worse at altitude, and there is no convincing evidence that childhood seizure disorders are affected by altitude. Acetazolamide is probably safe in children, but interventional studies have not been done in children going to altitude.
"Am I just another backpack?" The major issue, Dr. Neumann reminded workshop participants, is that families should keep the child’s perspective in mind when planning trips. The child should not be considered as just another appendage to the parents’ life. The activities and itineraries should be designed with the child in mind. If the child’s voice could be heard, many "leisure" trips would be canceled or postponed. Travel medicine practitioners can try to instill a good dose of common sense into family travel planning.
John Christenson, a specialist in pediatric infectious disease and pediatric travel medicine at the University of Utah, then treated workshop attendees to a discussion of diarrhea in traveling children. He reminded the gathered crowd that the epidemiology of travelers’ diarrhea is similar in adults and children but that risk does vary a bit with age.
Dr. Christenson made it clear that children are not just "little adults." Medical therapy must be instituted with caution in young travelers. Diphenoxylate (Lomotil) can cause central nervous system effects and should be avoided in children. Kaolin-pectin combinations are not effective. Loperamide (Imodium) is effective at an adequate dose (0.8 mg/kg) but has been associated with some lethargy, sleepiness, and abdominal distension; it is generally not advised for young children, particularly those younger than 2 years of age. Probiotics such as lactobacillus seem harmless and might provide some protective efficacy; studies are continuing. Bismuth subsalicylate is somewhat helpful and can be used if needed, but it does carry a small theoretical risk of Reye syndrome.
Children, Dr. Christenson noted, should not be considered "second class citizens." Thus, it is not sensible that antibiotics considered ineffective against organisms currently causing diarrhea in traveling adults would be used in children. Since the organisms causing travelers’ diarrhea are the same in adults and children and since antimicrobial resistance to trimethoprim-sulfamethoxazole has removed this agent from use as presumptive treatment in adults, then children, too, deserve more appropriate therapy when they have diarrhea. Since trimethoprim-sulfamethoxazole is no longer effective against many of the microbes causing diarrhea in traveling children, what other antibiotic should be used?
Azithromycin is highly effective against the organisms causing travelers’ diarrhea, and it is safe in children. Though not licensed for use in pediatric patients, ciprofloxacin has been used in children and does not seem to cause joint or cartilage problems. Thus, one of these two agents should probably be the first choice for presumptive therapy of travelers’ diarrhea in children.
Travelers’ diarrhea, however, is a self-limited illness, and oral hydration can prevent the devastating consequences. Should antibiotics even be offered for presumptive treatment to children? In two reported studies of pediatric travel clinics, more than half of traveling children were offered antibiotics to use in the event of diarrhea. The hallways of the Westin Galleria continued to buzz with debate for more than 24 hours after Dr. Christenson’s presentation. There is not full agreement about whether antibiotics should be used for travelers’ diarrhea. Adding to the debate, however, Dr. Christenson provided clear reminders that effective antibiotics such as azithromycin and ciprofloxacin can indeed limit the duration and severity of diarrhea in traveling children as in traveling adults.
So, what should be done about diarrhea in traveling children? First, families might need to reconsider whether it is worth exposing their children to prevalent enteric flora; some trips might be postponed. Second, the use of oral rehydration and breastfeeding should be encouraged. Third, we should advocate for clean play areas and clean hands as well as for hygienic food and water. Prophylactic medications should not be used, and antibiotics should be limited to those that are effective such as azithromycin and, perhaps, ciprofloxacin. Antimotility agents should not be used in children younger than 2 years of age, but bismuth subsalicylate can be used if needed. And, children with bloody diarrhea should avoid antibiotics while seeking medical care.
Drs. Mackell, Neumann, and Christenson were well received. They managed to put available data before their audience and were able to suggest wise management decisions for the areas in which data are limited. Not all the controversies were resolved, but many participants were grateful to return to their practices better armed with a scientifically sound approach to the care of traveling children.
2. Parkins KJ, et al. Effect of exposure to 15% oxygen on breathing patterns and oxygen saturation in infants: Interventional study. BMJ 1998;316:887-891.
3. Yaron M, et al. The diagnosis of acute mountain sickness in preverbal children. Arch Pediatr Adolesc Med 1998;152:683-687.