Parents often give their infants acetaminophen (Tylenol) after immunizations and booster shots. As it turns out, this may do more harm than good. The medication may actually weaken infants’ immune systems, according to research from the Czech Republic.

Acetaminophen is sometimes given to infants and small children following shots to prevent fever, a common reaction to vaccinations. This study examined the effects of acetaminophen on immune response after initial and booster vaccinations.

Two hundred twenty-six children from 10 different medical centers were randomly selected to receive three doses every six to eight hours for 24 hours after immunizations. Just 42 percent of these children experienced fevers (100.4 degrees F or above), compared to 66 percent of a control group of 233.

When it was time for booster shots, parents were asked to repeat the process. There was a lower incidence of fever in both groups—36 percent for those who took acetaminophen and 58 percent for those who did not.

Children who received acetaminophen , however, had fewer antibodies, indicating more susceptibility to disease. In the studied children, pneumonia, hepatitis B, whooping cough, polio, diphtheria and tetanus antibodies were fewer following vaccinations and boosters with acetaminophen use.

Antibodies are proteins in the immune system (immunoglobulins) that bind to harmful pathogens (viruses) to keep them away from healthy white blood cells. Without these antibodies, the body’s immune system is more susceptible to disease.

When vaccines fail to protect against diseases, the health of the entire community is at stake because viruses are more easily spread.

“This point has implications, especially for Haemophilus influenzae, for which higher and sustained antibody concentrations are needed (to reduce transmission),” says Dr. Robert T Chen of the Centers for Disease Control in Atlanta, “…and for pertussis, the bacterial vaccine-preventable disease that is least controlled.”

Although they’re not entirely sure why children taking acetaminophen had fewer antibodies, doctors plan to explore the issue further. They stress the importance of this information, and advise against unnecessary acetaminophen use.

“(A)dministration of antipyretic drugs at the time of vaccination should nevertheless no longer be routinely recommended without careful weighing of the expected benefits and risks,” wrote lead author Dr. Roman Pryula of the University of Defense in Hradec Kralove, Czech Republic.

The study appears in this month’s online issue of The Lancet.

Your showerhead may be home to some very dangerous bacteria. A new study from the University of Colorado at Boulder may have you cringing rather than singing in the shower. People with compromised immune systems may want to take a bath.

Researchers studying the microbiology of water systems at 45 sites in seven different states across the U.S. found unusually high levels of bacteria in showerheads—almost 100 times more than any other place in the home. Although bacteria levels were high in all showerheads, some sample sites in the New York City and Denver areas had large amounts of Mycobacterium avium, a relative of the bacteria that causes tuberculosis and leprosy.

“If you’re getting a face full of water when you first turn your shower on, that means you are probably getting a particularly high load of Mycobacterium avium,” says study author Norman Pace, professor of biology at the University of Colorado.

Mycobacteria are found in soil, water, and decaying matter. Certain Mycobacteria, such as Mycobactrium avium, can cause digestive, lymphatic, and pulmonary infections. In the shower, these bacteria are delivered as aerosols. Particles are small enough to get into the lungs, and when inhaled or swallowed, can lead to a host of pulmonary problems.

The study, part of a bigger study that began as a class project, used DNA barcode testing to extract rRNA (bacterial DNA) from different parts of the shower and showerhead. Researchers sampled water flowing from the showerhead and obtained swab samples from the inside of the showerhead. Finally, samples were collected from water flowing out of the pipe after the showerhead was removed.

Homes with well water systems did not have Mycobacteria in their showerheads, a factor authors believe may be due to Mycobacteria’s chlorine resistance. Although they suggest that bathing may be safer, researchers assure that it’s not dangerous to shower.

“We did see some organisms that might be of concern if you have immune issues (such as) cystic fibrosis, AIDS, recent organ transplant, substance abuse, or are pregnant or otherwise immune compromised,” the authors wrote.

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