Section 17 Diphtheria

Introduction of Diphtheria

Diphtheria is an acute respiratory infectious disease caused by diphtheria bacillus （Corynebacterium diphtheriae）. In most cases the bacillus is transmitted in droplets of respiratory secretions，propagating in respiratory membrane，and then producing exotoxin causing lesions. The propagation of the diphtheria bacilli leads to the formation of a thick，leathery，grayish pseudomembrane around throat and occasionally accompanied by systemic toxemia. In some severe cases and cases failing to get effective treatment，they may develop myocarditis or paralysis of peripheral nerve.

Diphtheria bacillus rigidly parasitizes in human body，so patients and carriers are the exclusive infection source. The contaminated materials also can transmit this disease besides droplets. There are significantly differences in susceptibility to diphtheria among different age groups. A more persistent immunity to this disease can be obtained after the disease，frequent relapse is also reported.

At present，the morbidity and mortality of diphtheria has dramatically decreased. Diphtheria is perennial，but reaching peak in autumn and winter，and sagging down in summer. In the past years，diphtheria usually plagued children but now it imposes a high morbidity to the adults. Diphtheria has a high mortality.

Diphtheria develops slowly manifesting sore throat，fever，malaise，discomfort，congestion in throat，swollen tonsils，and formation of fleck pseudomembrane 24 hours later. The pseudomembrane becomes thick and expanded appearing grayish color. Edge of the pseudomembrane is sharp and it is difficult to be torn away. Tearing of the fleck with violence may cause bleed in the basal membrane. In more severe cases，systemic toxic symptoms develop and the pseudomembrane becomes expanded and thickened with grayish color and foul smell. In the most severe cases systemic toxicity deteriorates and the pseudomembrane expands with black color and rotten smell. Neck of the patient resembles cattle’s neck，which is threatened the life.

1. Laboratory data

（1） Positive isolation and culture of diphtheria bacillus，which can produce evidenced toxin.

（2） Bar-like Gram stain positive bacillus with metachromatic granules can be found by throat-swab direct smear.

（3） 4 folds or higher increased in serum specific antibody titer between acute-phase and convalescent sera

2. Major measures dealing with the measles epidemic

（1）Suspected cases and cases：

early discovery，early diagnosis，early reporting，early isolation，and early treatment. Carriers and close contacts can be treated with prophylactic antibiotics.

（2）Cutting off transmission routes：

conducting disinfection by exposure to sunlight，phenol or lysol. Clean ward using wet cleaning and ventilation，and final disinfection is needed.

（3）Protection of susceptible populations：

taking personal protection measures such as wearing masks，distancing from measles patients and receiving emergency immunization.

白喉流行病学个案调查表

Epidemiological Questionnaire for Cases of Diphtheria

Questionnaire

（本节编者-马钰　本节核对-吴迪）