While we waited for the results we put the baby in the hospital and treated with intravenous antibiotics.

But in most cases, the aggressive treatment was unnecessary, because the cultures yielded no bacteria. Fortunately, there has been good epidemiologic research in recent years to help predict which babies really need to be hospitalised.

Nowadays, anyone under 1 month old who develops any fever still tends to end up in the hospital.

For babies older than 3 months, we now use clinical judgment: if they appear well, we might order a blood or urine test, but they can go home, as long as we stay in touch with the parents.

Between 1 and 3 months is still a gray zone. And in this case, there were a few other subtle shades of gray, notably the fussiness and reluctance to nurse: after all, an infant with a serious infection has a limited repertory of signals to say, “Hey, Mom, something’s wrong.”

Did his temperature really constitute a fever? As it happened, it fell on the cut-off for “real” fever -- 38 degrees Celsius, or 100.4 Fahrenheit.

So age right on the borderline, fever right on the borderline, and story right on the borderline.

Here are the doctor’s options

* Examine the baby carefully and if he looks good and the temperature isn’t climbing and the mother seems comfortable and competent, send them home and tell the mother to watch carefully.

* Get a blood count to check for serious infection, and maybe a urine test to be sure there’s no evidence of a urinary infection.

... contd.