Whooping Cough at Mary Ellen Henderson Middle School

By CHRISTINE KILGORE
Falls Church Times Staff

May 25, 2010

Fairfax County Health Department officials have been working over the past several weeks to prevent the spread of pertussis in Mary Ellen Henderson Middle School, urging parents to keep children with symptoms at home until seen by a doctor and encouraging preventive medication in some children deemed to have had close contact with an infected student.

Pertussis, or whooping cough, is a bacterial, communicable illness that can be especially serious for infants and young children who have not yet completed the primary series of DTaP vaccine that protects against infection.

It is a reportable illness (physician and hospitals are required to report diagnosed cases) that, at least in Fairfax County, uniformly generates a public health response.  And paradoxically, it’s a vaccine-preventable illness whose rates have been rising since the 1980s rather than falling.

And then there’s the fact that pinpointing suspect cases among  children who are coughing from allergies, asthma, colds, and other infections is no easy feat.

As my 11-year-old daughter said recently, “everyone is coughing!”

Her class—the 5^th-grade—has borne the brunt of this episode.  The medical community has learned over the years that the immunity created through vaccination wanes over time—and for the past 4 years, students have been required by state law to have a booster dose of pertussis vaccine to enter 6^th grade.

For at least some families, getting the booster is still on the ‘to-do’ list—and consequently, the 5^th grade overall is the most susceptible to waning immunity and the spread of infection.

“We used to see kids in the 6^th and 7^th grade getting pertussis, but now we’re seeing less of that,” said Fairfax County Health Department’s Dr. Peter Troell in an interview last week. “Now we see cases still among the 5^th graders, and among some of the older high school kids who didn’t have to meet a [6^th-grade booster] requirement.”

It’s “not uncommon” for the health department to investigate cases of pertussis in schools, said Dr. Troell, medical epidemiologist for the health department.  “Generally, when we see pertussis, we see 1, 2 or 3 cases [in any school].”

Pertussis in adolescents and other individuals who were vaccinated earlier in life often is mild, and according to Dr. Amin Barakat of Northern Virginia Pediatric Associates, may even go “unrecognized” in mild cases.

Often, Dr. Troell explained, “those who are vaccinated have only a little bit of feeling bad before the cough onset, maybe a bit of a runny nose, and then go into a cough that’s milder than what’s described for the classic case of pertussis.”

It can be difficult sometimes to distinguish pertussis from, say, allergies that aren’t well treated, but generally the cough associated with pertussis is more persistent, he said.

Classic pertussis is characterized by a period of cold-like symptoms that progresses to bursts or spasms of severe coughing and characteristic whooping that can be severe enough to induce vomiting. Before killed whole-cell pertussis vaccine was introduced in the 1940s, whooping cough was a major cause of infant death worldwide. (The safety of whole-cell pertussis vaccines prompted development of the acellular vaccines used today.)

Today, there are still reports of major complications—from hypoxia and pneumonia to encephalopathy and death-among children who are unvaccinated or too young to be vaccinated. Vaccination and preventing spread through communities are thus key public health goals.

MEH Principal Dr. Ann McCarty informed MEH parents in mid-April about a case of pertussis and asked that children with persistent cough see their physician and, if pertussis is confirmed or suspected, stay home until 5 days of an antibiotic regimen is completed. This month, parents of children who were deemed through “contact tracing” to have had close contact with an infected student were asked by the FCHD to “see a physician for preventive medication.”

(In this case, prophylaxis is identical to the treatment—the same antibiotic regimens. Though not without any controversy, judicious use of antibiotic prophylaxis for household and close contacts is a common public health recommendation.)

The most accurate test for pertussis involves a nasophayngeal swab, Dr. Barakat says. Results can be ready in 48-72 hours.

The increase in pertussis since 1980 has disproportionately affected adolescents and adults, and for several years now the Centers for Disease Control and Prevention has recommended “catch-up” use of a pertussis-containing booster vaccine in adolescents who did not receive a booster at 11-12 years old. Adults younger than 65 who haven’t had pertussis-containing vaccine as an adult can also substitute one of their tetanus-diphtheria boosters with  a Tdap vaccine.

Such advice holds weight for me: A friend of mine had pertussis last summer and it wasn’t easy. Before being diagnosed and treated, she had a difficult time with posttussive vomiting. According to an infectious disease report I recently read, numerous studies have suggested that pertussis comprises 20-30% of all cases of persistent cough among adults lasting two weeks or longer.

Interestingly, though, pertussis is no longer contagious after a person has been coughing for more than 21 days, Dr. Troell said.

And certainly, there are many questions still challenging physicians and researchers—about pertussis pathogenesis and immunity in adolescents and adults, for instance, as well as how to best prevent and control outbreaks.