1 March 2004

Meet the metapneumovirus

In young infants with a lower respiratory tract illness, infection with the RNA virus human metapneumovirus accounts for a substantial proportion of cases that would previously have been relegated to the "undiagnosed" category, say US experts.1 They believe human metapneumovirus infection is probably less common than respiratory syncytial virus infection but more common than parainfluenza virus infection.

The experts were commenting on a US study conducted in a primary care clinic over a period of about 25 years (1976–2001), in which more than 2000 normal children were followed from birth at full-term to up to 5 years of age.2 By using newly available molecular studies as well as culture, the study was able to prove that 49 of 248 snap-frozen nasal-wash specimens taken from children with lower respiratory tract infection and previously found to be negative for viruses were actually positive for human metapneumovirus.

About three-quarters of the cases occurred in the first year of life (mean age, 11.6 months; range, 1.5 to 50 months). Infection occurred most frequently in late winter, with a spectrum of disease somewhat similar to respiratory syncytial virus infection; bronchiolitis or croup were frequent diagnoses.

The study also found human metapneumovirus in samples from children with upper respiratory tract infection but in only one asymptomatic child.

1. N Engl J Med 2004; 350: 431-433
2. N Engl J Med 2004; 350: 443-450

Buckle up, everybody

People who insist on not wearing a seatbelt when in a car could be putting the lives of others at risk in the event of a crash. US researchers have conducted a matched cohort study using data from the US national Fatality Analysis Reporting System for tens of thousands of passenger car crashes that occurred in the period 1988–2000. They found that restrained occupants were at increased risk of death within 30 days of an accident if they had had an unrestrained person sitting behind, in front of or beside them — these people had remained fixed in the path of someone else who was catapulted forward, backward or sideways. The risk of death was lowest when all occupants were restrained.

JAMA 2004; 291: 343-349

Net benefit

Interventions delivered via the Internet can probably reduce symptoms of depression in a subset of patients living in the community, say Australian researchers. Christensen and colleagues' randomised controlled trial in 525 individuals found that 6-week programs based on either BluePages, a psycho-education website offering information about depression (www.bluepages.anu.edu.au), or MoodGYM, an interactive website offering cognitive behavioural therapy (moodgym.anu.edu.au), were more effective in reducing symptoms of depression than a controlled intervention using phone calls. Study participants had to have Internet access, and turned out to be highly educated.

BMJ 2004; 328: 265-268

Short odds

Contrary to popular belief, people of short stature are no more likely to experience problems in their development than are individuals of average height, say UK researchers. They were reporting findings from the Wessex Growth Study, which has followed over 100 participants from the ages of 7–9 years to 18–20 years. The study found that adult personality functioning (eg, in domains such as education, employment, friendships and coping) was not affected by either height at study recruitment or height attained by adulthood. Similarly, aspects of daily living, such as drug-taking behaviour and experience of violence (which were nevertheless of concern), did not seem to be related to height.

Arch Dis Child 2004; 89:17-21

Putting x-rays under the cancer scanner

Radiological investigations, including computed tomography and angiography, may account for more than 400 cases of cancer each year in Australia, suggest UK researchers.1 They calculated estimates of the risk of cancer from diagnostic radiation exposure for each of 15 developed countries, including Australia (which "scored" the fourth highest estimate), by using information from various sources, including what is known about the effects of radiation on Japanese atomic bomb survivors. The researchers acknowledged that their estimates may overestimate the risk of cancer, being based on a fair few assumptions, for example that radiation-induced risks persist indefinitely.

An accompanying commentary points out that, although there is no threshold of radiation dose below which the absence of any cancer risk has been proven, equally there are no reliable data proving that radiation doses as used in diagnostic x-rays do, in fact, induce cancer.2

1. Lancet 2004; 363: 345-351
2. Lancet 2004; 363: 340-341

— Dr Ann Gregory, MJA