Virus is passed from parent to child in the DNA

A virus that causes a universal childhood infection is often passed from parent to child at birth, not in the blood but in the DNA, U.S. researchers said on Tuesday.

They found that most babies infected with the HHV-6 virus, which causes roseola, had the virus integrated into their chromosomes. Not only that, but either the father or mother also had the virus in the chromosomes, suggesting it was a so-called germline transmission -- passed on in egg or sperm.

"This is really a unique mechanism for congenital infections," said Dr. Caroline Breese Hall, a pediatrician at the University of Rochester Medical Center in New York who led the study published in the journal Pediatrics.

Her team is now investigating what this means for the children.

"If you have a chromosome that has got a virus integrated into it, what does it mean? What does it do? Can it activate again? Can it start spewing out virus and cause problems? Can you get an immune response to it?" she said in a telephone interview.

The questions are critical because nearly everybody is infected with HHV-6. It is a herpes virus that causes roseola -- an infection marked by high fever and the usual vague virus symptoms that may include respiratory or stomach problems.

About 20 percent of children also have a characteristic sudden rash that appears just as the fever breaks.

Hall's team studied 250 infants, 85 with HHV-6. Of them, 43 were born with the virus and 42 were infected later.

Most of the babies born with the virus -- a congenital infection -- had the virus in the chromosome. Hall said the assumption had been that the virus somehow crossed the placenta from mother to child, but in 86 percent of cases, it was inherited directly in the genetic material.

Just 14 percent were infected across the placenta.

Tests showed either the mother or the father -- but not both -- also had HHV-6 in the chromosomes.

"Because we know a parent already had the virus in the chromosome, we know that it didn't spontaneously wiggle its way in once the baby got it," Hall said.

There were several spots where the virus integrated into the DNA, but usually right at the end of the chromosome, where a key structure called the telomere is found. Telomeres protect the chromosome and are involved in aging and immune response.

The virus is everywhere in people who inherit it, Hall said. "In your hair, your nails, your skin, your blood, and at very high titers (levels)," she said.

The babies infected this way did not appear ill but Hall wants to follow them as they grow up to see if they develop normally. They all had antibodies to HHV-6, which is evidence of an immune reaction of some sort.

There is no drug licensed to treat HHV-6 infection.

Other viruses are known to integrate into the DNA and pass on from parent to child, but these so-called human endogenous retroviruses have never been known to cause symptoms or activate an immune response.

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High doses of vitamin D safe for children

Giving school children very high doses of vitamin D is safe, and may be necessary to bring their blood levels of the nutrient up to the amount necessary for optimum bone growth and health, a new study shows.

Insufficiency in vitamin D is common in children around the world, but there is little data on how much supplementation kids need, or even how much vitamin D they should have in their blood, Dr. Ghada E.-Hajj Fuleihan of the American University of Beirut in Lebanon told Reuters Health. "In the pediatric literature, we don't have a lot to guide us," she said.

In a previous study, Fuleihan and colleagues found that giving 10- to 17-year-olds relatively high doses of vitamin D3 increased their bone mass and bone area, as well as lean mass. In the current study, they report on both the short- and long-term safety of high-dose supplementation.

The short-term study included 25 school children randomly assigned to receive a placebo or 14,000 international units (IU) of vitamin D3 per week for eight weeks. In the long-term study, 340 study participants took placebo, 1,400 IU weekly, or 14,000 IU a week, and were followed up at six and 12 months.

Currently, the Institute of Medicine recommends a daily vitamin D3 intake of 200 IU for children. The high dosage used in the current study was 2,000 IU daily, or 10 times that amount.

No signs of vitamin D intoxication were seen in any of the children, while levels of the vitamin in children treated short-term rose from 44 to 54 nanograms per milliliter (ng/mL).

In the long-term study, levels rose from 15 to 19 ng/mL in children given 1,400 IU weekly and from 15 to 36 ng/mL in the higher-dose group. Levels were initially higher in the short-term study because it was conducted among children in a higher socioeconomic group, and took place in the summer, when kids are likely to get ample sunshine and thus have adequate blood levels of the vitamin, Fuleihan and her team explain in the Journal of Clinical Endocrinology and Metabolism.

Based on studies in adults, Fuleihan said, blood levels of vitamin D below 5 ng/mL are agreed to represent deficiency, while levels above 20 ng/mL are considered adequate and most experts say 30 ng/mL is ideal.

Because every additional 100 IU of vitamin D3 consumed produces a roughly 1 ng/mL increase in blood levels, high doses may be needed for children with vitamin D insufficiency, the researcher said.

Nevertheless, she added, more research is needed to understand how much vitamin D children should be getting, and whether there are health effects of vitamin D insufficiency beyond bone and muscle, as studies in adults suggest.

"The pediatric literature is lagging maybe 10 to 15 years behind the adult literature in understanding the impact of low vitamin D on health," the researcher said.

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Cell phone exposure and behaviour

Children whose mothers used cell phones frequently during pregnancy and who are themselves cell phone users are more likely to have behavior problems, new research shows.

The finding "certainly shouldn't be over interpreted, but nevertheless points in a direction where further research is needed," Dr. Leeka Kheifets of the UCLA School of Public Health, who helped conduct the study, told Reuters Health. "It's a wonderful technology and people are certainly going to be using it more and more," she added. "We need to be looking into what are the potential health effects and what are ways to reduce risks should there be any."

Kheifets and her team looked at a group of 13,159 children whose mothers had been recruited to participate in the Danish National Birth Cohort study early in their pregnancies. When the children reached age 7, mothers were asked to complete a questionnaire about their children's behavior and health, as well as the mother's own cell phone use in pregnancy and the child's use of cell phones.

After the researchers adjusted for factors that could influence the results, such as a mother's psychiatric problems and socioeconomic factors, children with both prenatal and postnatal cell phone exposure were 80 percent more likely to have abnormal or borderline scores on tests evaluating emotional problems, conduct problems, hyperactivity, or problems with peers.

Risks were higher for children exposed prenatally only, compared with those exposed only postnatally, but were lower than for children exposed at both time points.

Kheifets and her colleagues note that a fetus's exposure to radiofrequency fields by a mother's cell phone use is likely very small. However, they add, research has shown that children using cell phones are exposed to more radiofrequency energy than adults, because their ears and brains are smaller.

Because cell phone use was so infrequent among children in the study - 30 percent of kids were using a cell phone, but just 1 percent used a cell phone for more than an hour a week - radiofrequency exposure seems unlikely to have caused any behavior problems, they say.

"Another possible explanation for the observed association might be the lack of attention given to a child by mothers who are frequent users of cell phones," the researchers suggest. They note that mothers who used cell phones frequently were of lower socio-occupational status, more likely to have mental health and psychiatric problems, and more likely to have smoked while they were pregnant.

No matter what the factors behind the association are - if there indeed is a real relationship between cell phone use and behavior problems--one simple way to reduce exposure to cell phones would be to use hands-free technology, Kheifets said in an interview.

Editorialists writing in the journal raise the question of whether the publication of these findings may scare people for no reason.

Kheifets and her team believe that while their findings are preliminary, they should be reported. "We felt that the public is quite capable of dealing with proper information," the researcher said. "One shouldn't really try to be paternalistic about it."

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