PedSPAM March 1998

Welcome to PedSPAM for March. Here are some things from my update reading. This month's news is digested from various sources.

In the News

This month, the PedSPAM spotlight is focused on pertussis (whooping cough), to remind you of the importance of childhood immunization, and to warn you of the danger of adult pertussis disease.

Pertussis is a disease which was once very common in this country. It was brought under some degree of control; now it seems to be increasing in incidence again. This fact has brought renewed interest in trying to control this disease. To give a little perspective, in 1923, 9,000 people died of pertussis. In the 1930s, there were about a quarter of a million cases of pertussis per year. Immunization began in the 1930s; by 1970 the number of cases had fallen to about 1,000 per year. By the late 1980s, pertussis started its comeback in the US, with numbers of cases peaking in the several thousands in several recent years.

The causative organism is usuallythe bacterium Bordatella pertussis, but sometimes the related organism Bordatella parapertussis. In the unvaccinated person, the disease lasts 6 to 10 weeks. Classically, the disease has three stages: catarrhal, paroxysmal, and convalescent. After an incubation period of 3-12 days, the patient develops cold symptoms - a clear runny nose, sneezing, perhaps some fever. This is the catarrhal phase. As these symptoms wane, the child begins to develop a dry, hacking cough, which builds in intensity over time. As the cough progresses in severity, the least stimulation or startle can trigger a long paroxysm of hacking cough which ends in a sharp drawing in of the breath - the "whoop." Post-cough vomiting is classic and very suggestive of the diagnosis. Between paroxysms of coughing, the children appear well. This is the paroxysmal phase. Gradually these symptoms abate in the convalescent phase.

Infants have the highest hospitalization and complication rates. Fifty percent or more of infants who contract pertussis are hospitalised. Twenty-five percent develop pneumonia; four percent develop seizures, one percent suffer permanent brain damage and another one percent die. Pertussis infection in the very small infant might also be implicated in some apparent SIDS cases.

Symptoms af adult pertussis generally do not include the "whoop," but can include the paroxysms of severe cough, postcough vomiting, urinary incontinence (!), pneumonia, and otitis media. Broken ribs are very common in full-blown adult pertussis. Imagine coughing hard enough to break your ribs.

Young children who get pertussis usually catch it from adults. The pertussis germ is widespread in the adult population, a fact unknown to parents and unfortunately, to many doctors who care for adults. For example, 26% of those students at the University of California at Los Angeles who had a cough that lasted more than five days had pertussis. Very similar percentages of adult incidence have been established around the developed world. Doctors who care for adults rarely even consider the diagnosis of pertussis in an adult unless the patient has a classic whoop at the end of the cough - a symptom which can often be absent. They generally refuse to consider the diagnosis even if the patient himself mentions it (imagine that - a doctor not listening to the patient...)! Yet another study showed that 20% of adult patients with any cough lasting more than a week were blood test positive for pertussis infection.

"It should be suspected when an illness thought to be a cold is associated with the development of a paroxysmal cough that worsens at night and is nonproductive. Between coughing attacks, the patient with pertussis has no symptoms; this fact is useful in differentiating pertussis from cough illnesses caused by respiratory viruses or allergic conditions." - James D.Cherry, MD, MSc, Ann Intern Med.1998;128:64-66
This means that your child is very likely to come into contact numerous times with adults who are actively spreading the infection. Adults suspected of having pertussis should be treated with erythromycin for 14 days. Early treatment will shorten the course of the illness and eliminate the risk for transmission.

Mothers with even mild symptoms are able to transmit the disease to very young infants. Unfortunately, the first dose or two of vaccine does not confer full immunity. The primary series and the fourth booster must be completed to fully protect your child. My last case of confirmed pertussis was in a five month old girl who had already had two DTP shots. She was "mildly" ill - she only coughed for three or four weeks and was "only" in the hospital for a week.

Unfortunately, pediatric immunization alone will never eradicate this terrible disease. Pertussis immunization wears off as we age, creating the large pool of susceptible adults. In addition, it is clear that immunity even after infection is not lifelong, and strangely, it seems that this type of naturally acquired immunity is inferior to that induced by immunization. Adult pertussis is very common in Germany, for example, where many patients get pertussis as children, then suffer from the same disease again in adulthood; these patients have more severe disease than that suffered by American adults who were immunized and later were infected when their immunity wore off.

Since 1955 there has been discussion of the possible need to re-vaccinate adolescents and adults. Since that time, it has been thought that the side effects of the vaccine in older individuals outweighed the possible benefits. Now, with the advent of several acellular (purified split-cell) vaccines, these concerns seem outweighed by the possible benefits of booster immunization. The new acellular vaccines are very well tolerated by adults, with very few minor side effects.

Experts are not ready to recommend universal pertussis re-vaccination for adults, but are studying the issue. It is more likely that a campaign for vaccination of high risk individuals such as pregnant mothers will be the result. However, it probably is possible to eradicate the disease in this country with a program of adult reimmunization, and I expect that to come within a few years.

(A peripheral issue of concern to parents as adults are the low immunization rates for all diseases for adults in the United States. For example, the immunization rate for adults over 65 - a high risk group - is 51% for influenza vaccine and 27% for the pneumococcal (pneumonia) vaccine. This leads to an estimated 7,000 preventable deaths from influenza and 17,000 preventable deaths from pneumonia in the elderly each year.)

If bacterial meningitis - infection of the brain and spinal cord - is suspected in a child, it is critically important to give a dose of a potent steroid called dexamethasone before or right along with the first dose of intravenous antibiotic. This reduces the risk of hearing loss as a complication of the infection. It can be overlooked by the doctor in the anxious moments in the emergency room, when antibiotics are usually started in suspected meningitis cases to avoid any delay waiting to go to be admitted to the hospital floor or ICU. But even one hour's delay in giving the steroid after the antibiotic makes the steroid benefit disappear - so if your child is suspected of bacterial meningitis, think of that steroid shot, too.

A study in New Zealand examined the risk factors for SIDS (Sudden Infant Death Syndrome) in that country.

An exciting new form of immunization is under development: expression library immunization or ELI. In this technique, pure synthetic DNA is reconstructed from the genetic code of a targeted disease germ and is injected into the patient. The patients own cells produce proteins coded by this foreign DNA and immunity is formed against these proteins, and thus against the germ. Thus the immunity is against the "expression" of the foreign gene in the body, not the gene itself. The term library refers to the fact that scientists are rapidly decoding the DNA of the worlds disease-causing germs and will soon have libraries of genetic code for all of them. By selecting parts of the library of, say, the tuberculosis bacterium, and testing to see whether that section of the code produces immunity against infection, researchers can hone in on those parts of the gene makeup of the germ and immunize against that part only. The purified DNA injections should have few if any side effects. This promises, along with the development of oral vaccination by genetically engineering immunity producing products into common foods, to absolutely revolutionize medicine in the coming years.

A new rabies vaccine has been licensed by the FDA. RabAvert is given either as a three-shot series over about a month for pre-exposure (high risk) prevention or as a five shot series. The vaccine is very well tolerated; rabies immunization is no longer the dreadful two weeks of daily abdominal injections of the old days. In case you wonder, four cases of human rabies were documented inb the US in 1997. Of the 36 cases of human rabies diagnosed in the US since 1980, 21 (58%) were known bat-born strains of the virus. Only one case had a definite history of a bat bite.

The National Immunization Information Hotline is available toll-free at 1-800-232-2522 (1-800-232-0233 for Spanish language services). This free service provides answers to vaccine related questions to parents, health care providers and members of the general public. It is available 8:00 a.m. to 11:00 p.m. EST Monday through Friday with voice mail at other times.

The number of chickenpox cases nationwide seems to be declining. It is not really know at this point whether this reflects an effect of use of the varicella vaccine, or if this is simply a normal year-to-year variation. Of course, we hope it is the former. The immunization rate for the varicella vaccine is rising. I was interested to note that one of my HMOs announced it would be using the varicella immunization rate as one of their measures of quality of care in my practice this year.

Also on a positive note, the increased emphasis on screening of pregnant women for vaginal colonization with the Group B streptococcus bacteria coupled with adoption of pre-delivery antibiotic treatment has led to a 24% drop in early-onset Group B strep disease in newborns.

Tetanus in the newborn, once common, is now almost unheard of in this country. So-called neonatal tetanus is a serious, life-threatening disease. It is caused by infection with Clostridium tetani, a germ which secretes a toxin which specifically stimulates muscle nerve receptors into a state of permanent overload, causing severe spasm and seizures. A recent case report pointed out that newborns of foreign-born mothers who did not receive adequate tetanus immunization are at risk for this dangerous disease. The affected infant was born to a Mexican immigrant mother who had only had one tetanus immunization at age 12. The birth was in a hospital under routine conditions - in contrast to the usual risk factors of home delivery by untrained personnel. She lived near a cattle pasture, and it was surmised that the spores may have come from this source - the droppings of livestock are rich in tetanus spores. Her baby recovered after a two month hospitalization (trust me - you do not ever want to see a case of tetanus). Expectant mothers born outside of the US need to be checked for a history of tetanus immunization and immunized if necessary.

Diet Management of Acute Diarrhea

An article in Pediatrics for December 1997 reminds doctors who care for small children that while immediate correction of fluid loss with oral rehydrating solutions (Pedialyte®, Ricelyte®, Infalyte®, KaoLectrolyte®, et al) is of course important, the common practice of restricting solids foods and milk from the diet of patients recovering from diarrheal disease is without good basis in medical research and may lead to inadequate energy intake for quick recovery.

This is not news to many; it has been shown a number of times by American researchers that in other countries where solid and milk feedings are restarted as soon as vomiting stops, the recovery rates are better than in the US. This is thought to be explained by the fact that the gut requires a lot of energy to repair itself after a bout of gastrointestinal infection. Starvation is known to lead to loss of the absorptive capacity of the small intestine, and a viscious circle can result where starvation leads to gut dysfunction, which leads to more diarrhea caused by food malabsorption, which prompts the doctors and caregivers to restrict oral caloric intake even further.

"Resting the gut" is a widespread practice belief among doctors, but has little if any basis in science for the common childhood diarrheas. Early feeding may make the diarrhea appear to worsen because feeding stimulates the gastrocolic reflex, but it probably promotes earlier gut healing and recovery from the diarrhea.

Grandmothers know that sick babies need to eat, and they are right!

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