Anti-PT IgG results from 227 patients with coughs of unknown etiology who reported the severity of cough on a scale from 0 to 10. Anti-PT IgG results from 227 patients with coughs of unknown etiology who reported the severity of cough on a scale from 0 to 10. Results are plotted against severity of cough, with 0 corresponding to “No particular effect on well-being,” 5 corresponding to “Very uncomfortable, major reduction of work ability and sleep,” and 10 corresponding to “Unbearable, very painful, constant fear of suffocation.” Tine Dalby et al. Clin. Vaccine Immunol. 2010; doi:10.1128/CVI.00270-10