Diphtheria in Andhra Pradesh-a clinical-epidemiological study

Clinical diphtheria is on the increase worldwide, mainly affecting developing countries. We sought to understand its presentation among patients at Sir Ronald Ross Institute of Tropical and Communicable Diseases in Hyderabad, Andhra Pradesh, India.

Diphtheria patients presented with fever, pharyngitis, and a patch in the throat. Data collected for each patient included age, clinical presentation, morbidity, mortality, bacteria isolated from culture, and immunization status.

Of 61 950 admissions from January 2008 to December 2012, 2925 (4.7%) had clinical diphtheria; 1194 had been immunized and 1731 were non-immunized. Immunized patients had a milder disease. Culture-positive immunized patients were positive for Corynebacterium other than diphtheriae (COD; n=104) or Corynebacterium diphtheriae (CD; n=23); these patients suffered mild disease and recovered completely. In contrast, culture-positive non-immunized patients were positive for COD (n=11) or CD (n=412). Eighty-one patients (3%) died, 77 of whom were non-immunized; death was usually as a result of myocarditis. Seventy-three percent of deaths were in patients aged <5 years.

The clinical presentation of diphtheria and its severity and morbidity differ considerably in immunized and non-immunized patients. Disease caused by CD can be deadly, while disease due to COD is mild and responds to treatment.