PedSPAM January 1998 Update

This is a PedSPAM special update for mid-January. I have been busy as a little beaver in the office but found some time to digest some things from my update reading and add a few topics to the Encyclopedia, which now contains 269 entries by my count. This month's news is digested from various sources. The main topic of interest is a quick review of influenza A, which is starting to hit here and probably in your town as well.

Influenza A

Influenza A is on the move. At least 47 states report outbreaks, including Alabama, my home state.

The influenza virus is a large, single-stranded RNA virus. The influenza virus resides in animal populations, and then is transmitted to humans - hence the concern with the avian flu in Hong Kong. The virus is characterised with many different antigenic strains. That is, immunity to one strain does not immediately confer immunity to the next variation down the pike. Thus influenza vaccines must be reformulated each year to cover the prevalent strains of virus. If a sufficiently new strain appears which is unknown to the immune systems of the general populace, a 'pandemic' is possible where literally millions of people become ill in a short period of time. If the virus is especially virulent, many deaths can occur directly and from complications, as in the great 1918 influenza epidemic that killed an estimated 20 million people worldwide.

Influenza generally peaks in 2-3 weeks after hitting a community, spread in a considerable part by young children. Young children are the most effective transmitters of the virus; because of their low levels of initial immunity, they shed higher levels of the virus, and for a longer time than adults. The attack rate in young children can be 30-50%. Young children who have never been exposed to the influenza virus have no immunity, except a fleeting bit of immunity passed from the mother before birth.

The viral infection mainly attacks the respiratory tract lining cells. Symptoms of the disease may thus localise anywhere in the respiratory tract, producing upper respiratory infection symptoms (cold), involvement of the larynx and trachea (croup), the large breathing tubes (brochitis), or the smaller breathing tubes (bronchiolitis), or the air sacs of the lung itself (pneumonia). Patients also experience generalised systemic symptoms of high fever, myalgia, malaise, and headache. Children with the flu can look quite sick and may need laboratory workup to sort things out.

Common complications in children are ear infection (otitis media) and pneumonia, usually a secondary bacterial pneumonia but often viral. With uncomplicated influenza, the first 48 hours are the worst. Thus if the child starts to get better, then seems to worsen, parents should suspect complications and seek medical consultation. Cough is a prominent symptom of the flu, and the cough may persist for up to several weeks after the initial illness has subsided. Flu patients may experience tiredness and residual symptoms for up to a few weeks after the initial illness.

Amantadine (Symmetrel®) is a drug which if given in the first 48 hours of illness reduces the severity and length of the illness. Confusion, inability to concentrate and sleeplessness are side effects of the drug that some patients report.

Track the progress of the flu with the CDC on the web.

Remember that iron in overdose is deadly. A case report appeared in the Southern Medical Journal concerning a 13 month old child who died of iron intoxication after ingesting prenatal vitamins. The 3 year old sibling had been checked 12 hours earlier at another hospital for suspected iron ingestion; if you have more than one child, remember to consider the possibility the other children may have gotten into the medicine.

Maternal smoking was the strongest independent risk factor for Neisseria meningitidis ("spinal meningitis") in a study of the disease in children through age 18 years.

Which method hurts less for obtaining blood specimens? A comparison of relative pain scores in newborns showed that venipuncture (arm stick) was less painful for the patient than heel stick. I think the consensus among children old enough to report might be different. The whole issue of which hurts more, armstick or fingerstick, is bound up in the fact that a needle is inherently more frightening and fear tends to make patients tolerate pain less well.

Several studies were reviewed on my monthly update tape regarding emergency contraception. Emergency contraception is different from abortion in that hormones (an estrogen/progestin combination or levonorgestrel alone) are given within 72 hours of intercourse to block ovulation. No egg is released, thus conception does not occur. Side effects of the treatment are not inconsiderable (perhaps a third of women experience nausea or vomiting) but preferable to unwanted pregnancy. Emergency information about this procedure can be obtained by calling a 24-hour hotline, 1-888-NOT-2LATE (1-888-668-2528).

Multiple food allergies in exclusively breastfed infants. In breastfed infants, occasionally sufficient cow-milk antigens may pass into the breast milk and cause classic symptoms of cow-milk allergy in the baby - vomiting, colic, diarrhea, and eczema. Investigators in France identified a small number of babies whose symptoms did not improve on a milk-free diet for mother, but were cured when several foods were removed from the diet. The symptoms reliably returned when the foods were reintroduced to mother's diet. This is really rare. In my experience, very few women need worry about anything at all in their diets. I always counsel mothers to be careful about jumping to conclusions about suspected milk or food sensitivities in their babies. If several trials over a period of time show the child to be sensitive to the suspect food in the maternal diet, then avoid the food and get on with life.

New drugs for asthma and allergic rhinitis. These are diseases in which inflammation of respiratory tract tissues plays the major role. Blocking the inflammation directly is now the preferred focus of treatment. In the past, the preferred antiinflammatory agents have been topical steroids (inhalers for asthma and sprays for allergic rhinitis) but steroids can have disturbing side effects. Thus the search for non-steroidal antiinflammatory drugs. Leukotrienes are chemicals released by inflammatory trigger cells to activate the inflammatory response seen in the lungs and other respiratory membranes during asthma and allergy flare-ups. A promising new class of drugs for asthma and allergic rhinits, antileukotrienes, are now available in the US (zafirlukast and zileuton). The hope is that these drugs will enable patients to receive safer levels of steroid treatment while improving control of symptoms.

Researchers in Ireland studied ultrasound movies of fetuses and determined that as a fetus matures, the number of mouth movements over a given time period increased as the baby matured. Female fetuses were found to move their mouths more often than males. (I promise I did not make this up 8-) This is because female infants develop faster than males both pre- and postnatally.

A screening test is a test for a particular disease given to patients who have no symptoms (that is, are "asymptomatic"). Screening tests are generally cheap; they are designed to be sensitive (detect lots of possible cases of the disease) but not as specific (accurately identify actual cases of disease) as a diagnositic test. The routine screening dipstick urinalysis that camps and schools often require and that some physicians routinely do each year is probably not cost effective, to say the least. Total costs for all children screened are enormous and very few real problems are ever found this way. A single screening test at school entry is advocated by researchers at State University of New York, Buffalo.

A study of recurrent streptococcal infections in Scandanavia debunked the idea that pets (dogs and cats) are likely to be the reservoir of strep infection. It seems that pets get the strep germ from the humans, not the other way around.

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