ASPEN, COLO. — Routine vaccinations can be accelerated to protect very young travelers against infectious diseases in developing countries, Sarah K. Parker, M.D., advised at a conference on pediatric infectious diseases sponsored by Children's Hospital, Denver.
“They can be really protected by about 131/2 months of age,” said Dr. Parker of Children's Hospital and a faculty member in pediatric infectious diseases at the University of Colorado Health Sciences Center, Denver.
Dr. Parker also recommended that physicians do a pretravel assessment to identify additional vaccination requirements by endemic conditions in destination countries. The assessment would include consideration of chemoprophylaxis and counseling parents on ways to prevent infectious disease while traveling abroad.
“Infection only causes about 1% of traveler deaths. However, it is a large fraction of what causes illness while traveling,” she said. About 50%–70% of travelers become ill. About 40% of illnesses are diarrhea, which can be more severe and more prolonged in children.
Routine vaccinations can start at 6 weeks of age, she said, outlining an accelerated schedule. Babies can receive four doses of inactivated polio vaccine; three doses of DTaP vaccine, Haemophilus influenzae type b vaccine, and seven-valent pneumococcal polysaccharide vaccine; and two doses of hepatitis B virus vaccine by 14 weeks.
MMR can be given at 6 months, she said, but does not count. If given at 12 months, it can be followed by a booster at 13 months. The accelerated schedule also permits hepatitis A virus vaccine off-label at 12 months.
A family traveling to Africa's “meningitis belt” should use the polysaccharide conjugate vaccine for children older than 11 years, the polysaccharide meningococcal vaccine for children 2–11 years, and consider its use off label in younger children at high risk, she said. The polysaccharide vaccine has been studied at 3 months with a 12-month booster with a rise in titers against meningococcus A, the predominant strain in Africa.
Varicella zoster virus (VZV) and influenza vaccines cannot be accelerated, however.
If one is protecting against hepatitis A with hepatitis A immunoglobulin, Dr. Parker noted that hepatitis A IgG interferes with MMR and VZV. Therefore, MMR and/or VZV vaccines should be given 2 weeks earlier, she said, adding that hepatitis A vaccine and IgG can be given together. Hepatitis A IgG must be repeated every 5 months while the child is in an endemic area.
Dr. Parker urged primary care physicians to consider prevalence of disease in destination nations when reviewing itineraries. Influenza should not be overlooked, she said. It is endemic year-round close to the equator and from March to October in the southern hemisphere. She suggested stockpiling flu vaccine released in October for use through June 30.
Meningococcal vaccine is required for pilgrims making the hajj, Dr. Parker noted. She said it also should be considered, even if off label, for children heading to Africa's “meningitis belt” and other potential risk areas.
Causing 22 million cases a year, Salmonella typhi is a concern throughout the developing world, she said. She advised vaccinating anyone older than 2 years of age who is heading to an endemic area.
Two vaccines are options if typhoid is a risk, Dr. Parker said. The injectable capsular polysaccharide vaccine is approved for children over 2 years and can be given 2 weeks prior to travel. Oral live, attenuated Ty21 a virus vaccine is approved for children older than 6 years but cannot be given if the child is immunodeficient.
Yellow fever vaccine is indicated for travel to endemic areas and required by some countries unless contraindicated. It should not be given to infants younger than 4 months old and is contraindicated in infants 5–9 months of age. Because encephalitis can be a side effect, “you don't want to give it to someone who doesn't need it,” she advised.
Japanese encephalitis is a risk in parts of Asia. Mortality is high, however, with deaths in 5%–30% of those who develop symptoms, according to Dr. Parker.
If mosquito exposure is likely during an extended stay in an endemic area during the endemic season, she recommended vaccination with an inactivated virus. It is approved for persons over 1 year of age. Because severe allergic reactions can occur up to 10 days afterward, she said this vaccine should be given at least 2 weeks in advance of travel.
No drug can prevent malarial infection, Dr. Parker said, but some agents can prevent disease. For pediatric considerations in prophylaxis, she referred physicians to a journal article (Semin. Pediatr. Infect. Dis. 2004;15:137–49).
Whether or not prophylaxis is used, families should try to prevent mosquito bites by making careful use of N,N-diethyl-m-toluamide (DEET), wearing permethrin-treated clothing, and covering exposed skin.