Diagnostic delays up household transmission of whooping cough

Secondary transmission of pertussis, also known as whooping cough, is highly prevalent in the household setting, according to a study, adding that delays in diagnosis can heighten the odds of spreading pertussis in the home.

The researchers conducted two population-based studies using a large nationally representative administrative claims database.

The first study used a stratified monthly incidence model in comparing the incidence of pertussis among participants exposed to a family member with pertussis relative to those not exposed. The second study was carried out at a household level following the index case of pertussis in each household. Diagnostic delays were identified in the initial household case. Finally, a logistic regression model was used to determine whether these delays contributed to a higher risk for transmission.

The incidence rate ratio of pertussis among participants with exposure to a family member with pertussis versus those with no exposure was 938.99 (95 percent confidence interval [CI], 880.19‒1,001.73).

In households where the index case had a diagnostic delay, the likelihood of secondary transmission was 5.10 (95 percent CI, 4.44‒5.85) times higher than when pertussis diagnosis in the index case was not delayed. Notably, longer delays significantly correlated with an increased risk for secondary household transmission (p<0.0001).

“Pertussis is a highly contagious respiratory illness that can be especially dangerous to young children,” the researchers said. “Transmission of pertussis often occurs in household settings and is impacted by the timing of treatment and postexposure chemoprophylaxis.”