This was further substantiated in vivo by a significantly lower leukocyte count in the parapertussis group as compared to the pertussis group. Frequencies of typical symptoms of whooping cough, such as paroxysmal coughing, whooping and vomiting, were almost identical in the two groups. Nocturnal coughing and contact anamnesis were noted more often in the Bordetella pertussis group. Children in the parapertussis group were significantly more often vaccinated with whole-cell pertussis vaccine than children infected with Bordetella pertussis. The results indicate that pertussis toxin may not play a decisive role in causing the typical symptoms of whooping cough, such as paroxysmal coughing, whooping and vomiting.
Antibody correlates of infection and symptomatology.
18 family members were subjects of a 1-year study to detect infection and antibody responses to Bordetella pertussis. Two-thirds of cases in these immunized contacts were subclinical. All infected family contacts had diagnostically elevated serologic tests for pertussis at the time the index case was diagnosed. Infected individuals had a mean of 5.5 of 10 antibody tests diagnostic for recent infection. Indexes cases and immunized contacts had different type and timing of antibody responses, making a single assay or sampling unable to identify all infected individuals.