You've probably heard the news: Measles, once banished, is back in a big way.

The reason, according to the Centers for Disease Control and Prevention (CDC): children are increasingly not being vaccinated against the highly contagious virus because of fears that ingredients in the injection may cause autism, a mysterious neurological disorder that affects one out of 150 children born each year in the U.S.

But new research by Columbia University's Mailman School of Public Health did not find a connection. "We are confident that there is no link between [the measles vaccine] and autism," says lead study author W. Ian Lipkin, an epidemiologist. 

The researchers hope their findings, published in the journal PLoS ONE, will put the issue to rest and persuade parents to vaccinate their children—a move that could stop measles and other, previously controlled serious illnesses such as mumps and whooping cough from making comebacks.

"We need to ensure the vaccine recommendations are followed to not only protect those who are immunized," says CDC researcher Larry Pickering," but to also provide herd protection for people in the United States and throughout the world who may not be able to receive the vaccine because of their age or respond to the vaccine because of an underlying immunodeficiency."
The CDC confirmed 131 measles cases in the U.S. between Jan. 1 and Aug. 1 of this year, more than double the number of cases reported annually between 2001 and 2007. Measles causes symptoms including an extremely itchy rash, high fever, runny nose and red eyes. Children generally receive their first vaccine against it at around 15 months old. Physicians started giving the vaccine in 1963; prior to that, the virus struck three to four million Americans per year and killed 400 to 500.

The CDC says that 91 percent of the current measles sufferers did not receive the shot or have evidence that they had gotten it. The major reason parents are nixing it: some studies since 1998 have indicated a possible link between the measles, mumps and rubella (MMR) vaccine and autism as well as gastrointestinal (GI) disorders. Rubella has similar symptoms to measles, but is generally milder although it can cause birth defects in fetuses of pregnant women with the disease; mumps causes high fever and painful swelling on one or both sides of the face.

One 1998 study found remnants of the measles virus in the intestines of children suffering from both autism and GI problems—estimated to be up to a quarter of the autistic population. Researchers hypothesized that the weakened measles virus used in the vaccine gathered and grew in the intestines, causing the immune system to attack, in the process damaging normal cells lining the bowels resulting in some seepage.
Such leakage could cause problems, such as abdominal pain and gastroesophageal reflux, which makes it difficult to digest food, and clear the way for the virus to enter the blood stream and travel to the brain.

The new study examined children, an average of five years of age, suffering from both autism and GI problems. "Although in fact there was evidence that this vaccine was safe in the bulk of the population," Lipkin says, "it had not been previously assessed with respect to kids with autism and GI complaints."

Researchers examined cells in biopsies (from 25 children with both autism and GI problems and 13 with just GI disturbances) to determine whether they contained genetic sequences of the measles virus. They only found a detectable amount of the virus remnants in one child in each group (4 percent of the autism and GI kids, 8 percent of the GI-only tykes). This indicates that autism is not related to the MMR vaccine or to the presence of measles sequences in the intestinal tract, says Columbia epidemiologist Mady Hornig, adding that the results were replicated in three different labs.

She notes that only 20 percent of the children with autism received the MMR shot before suffering GI problems and subsequent autism symptoms.

"From my standpoint, [this study is] just another brick in the wall to validate the vaccine safety issue," says Walnut Creek, Calf.-based pediatrician Rahul Parikh, who often counsels worried parents about the importance of vaccinating their children. "We still have parents coming in with a lot of concerns."

Rick Rollens, who has an autistic son who suffers from a "horrible bowel disorder," called the new research sound science and praised it for calling attention to an underserved subset of the autism spectrum: those children who also suffer from GI problems. But he insists that it does not give the all clear to all vaccines.

"I'm totally convinced that a vaccine caused the autism my child suffers from," Rollens says. "This study by itself does not exonerate the role of all vaccines"—only the MMR.