OBJECTIVE: The aim of this research was to describe the epidemiologic, clinical laboratory and microbiologic characteristics, complications and outcome of pertussis among pediatric patients at the Philippine General Hospital.
METHODS: A retrospective chart review was performed which included pediatric patients with final diagnosis of pertussis, both clinical and laboratory -confirmed admitted from December 2012 to August 2013 at the Philippine General Hospital.
RESULTS: This chart review included 28 pertussis patients highest in those aged 1-3 months (86%), females (57%) and from region 4A (57%). 26 (93%) had exposure to household members with respiratory symptoms and unknown pertussis vaccination status. Of those patients who were eligible for vaccination, only 24% received age-appropriate DPT vaccination.
Onset of illness varied from 3-56 days; majority 9/L, range: 14.7-111.5x109/L;), lymphocytic predominance (mean lymphocyte 0.47, range: 0.20-0.72;) and thrombocytosis (mean platelet count: 567x109/L, range: 269-823x109/L;). 28% were culture positive for B. pertussis, while 86% tested positive for PCR.
The most common complications  were pneumonia requiring mechanical ventilation (64%), ARDS (28%), seizures (21%), nosocomial pneumonia (11%) and myocarditis (11%). The average length of hospital stay was 7.4 days with 13 deaths or 46% case fatality rate. Deaths were attributed to respiratory failure due to progressive pneumonia and ARDS. Other contributing causes were arrhythmia, MODS, and  septic shock.
CONCLUSION: Susceptible young infants acquire pertussis from household contacts with respiratory symptoms. Paroxysmal cough and cyanosis are common clinical features, with leukocytosis, lymphocytosis and thrombocytosis. High case fatality rate for pertussis was noted among these patients.