April 27, 2007
Friday

ANCHORAGE, Alaska -- A vaccine given since 2001 has nearly wiped out seven of the worst strains of pneumococcal disease among Alaska children. But different strains not covered by the vaccine are on the rise among Native children, says a report published this week in the Journal of the American Medical Association.

The bacteria cause pneumonia, blood infection, meningitis and other diseases.

Non-Native Alaska children are not getting the new diseases at increased rates, said Dr. Rosalind Singleton, a pediatrician with the Alaska Native Tribal Consortium and a researcher for the federal Centers for Disease Control in Anchorage. She and colleagues wrote the journal report.

The researchers don't know where the newly blossoming strains came from, and can only speculate as to why they are surfacing at increased rates just in Native children. One possibility is that the new strains may be more easily transmitted in small village houses than in urban housing, said Singleton. And for children in villages without plumbing, hand-washing could be more difficult, she noted.

Alaska Native children are still better off than before, with about a 40 percent decrease in pneumococcal disease, said Singleton.

The bacteria cause serious illnesses, particularly among children and elders, said Singleton. If it invades the lungs, a child may get pneumonia. In the bloodstream, the disease is called bacteremia. In the covering of the brain, the bacteria cause meningitis. The bacteria can also cause middle ear and sinus infections.

The seven-strain vaccine, PCV7, resulted in a 96 percent decrease in these invasive pneumococcal diseases among Alaska children since 2004, the researchers' study showed. But strains not covered by the vaccine increased 140 percent in Native children compared with rates before the vaccine was used.

In the Bethel region, this meant more children coming in with bacteria in the blood stream last year, said Dr. Mehran Mosley of the Yukon-Kuskokwim Health Corp. "Suddenly a large number of children were coming in with bacteremia which I hadn't seen before," he said.

"The bugs that have emerged as the new culprits are all sensitive to simple therapies," Mosley said. "We haven't found anything terrible that we haven't been able to treat." But unexpected numbers of children are still getting sick from the new diseases.

A child with bacteremia may have a fever and act lethargic and less playful, Mosely said.

Singleton said researchers around the world have been looking into whether different strains will move in to take the place of those knocked down by the seven-strain vaccine, but Alaska is one of the first places to demonstrate that it is actually happening.

The PCV7 vaccine tackled strains that caused three-fourths of so-called invasive infections.

New vaccines are under development that might take care of emerging strains, she said. One is projected to be licensed in 2010, but that's not certain.

Pneumococcal disease rates are high in infants and children under 2, low for older children and young adults. The rates climb among older adults, Singleton said.

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