This specimen is from a 7-month-old infant with fever and very severe coughing attacks, sometimes up to vomiting. PCR revealed the bacterium Bordetella Pertussis in the throat. The leukocyte count was with a normal CRP.

This bacterium causes a highly contagious and life-threatening respiratory infection popularly known as whooping cough. What is special about this syndrome is that a lymphocytic reaction occurs, rather than a neutrophilic reaction as is usual in bacterial infections. In addition, the nucleus of a large number of lymphocytes shows marked cleavages. The combination of age, cough and lymphocytosis with cleaved nuclei is typical of this infection