Overview of Diphtheria
Diphtheria is an infection caused by Corynebacterium diphtheria (diphtheria). This disease affects the mucous membranes of the mouth, nose, throat and the skin of infected person. Once inside the body, the bacteria will produce diphtheria exotoxin that initiates a localized inflammatory reaction, leading to tissue necrosis. Clinical features of diphtheria include upper respiratory tract infection or cutaneous infection. The infection usually occurs in the spring or winter months and is communicable for 2-6 weeks without antibiotic treatment.
Causes and Risk Factors of Diphtheria
Human carriers are the main source of C. diphtheria. Infected patients and asymptomatic carriers can transmit disease via respiratory aerosols, nasopharyngeal secretions and fomites. In case of cutaneous disease, contact with wound exudates may also transmit disease to skin and respiratory tract. The risk factors for acquiring disease include overcrowding, poor health, deprived living conditions, incomplete immunization and immunocompromised state (HIV/AIDS). Exotoxin is released by C. diphtheria when it is infected by bacteriophage that integrates the toxin-encoding genetic elements into the bacteria. Cells of C. diphtheria adheres to mucosal epithelial cells where exotoxin causes an inflammatory reaction, leading to tissue destruction and necrosis.
Signs and Symptoms of Diphtheria
The symptoms can occur between two and five days after being infected. Symptoms can vary from mild to severe form. Disease starts with sore throat and fever and progresses gradually. The most common symptom of diphtheria is a thick, gray coating on the throat and tonsils. Other signs may include fever, chills, swollen glands, a blue tinge to the skin, a general uneasiness or discomfort of the body and drooling. In other cases, the person may have blurred or altered vision, difficulty in swallowing, slurred speech, signs of shock (pale and cold skin, sweating and rapid heart-beat). Cutaneous diphtheria symptoms include initial reddish lesions that are painful and that may develop into ulcers. Some ulcers may be covered by a gray-colored membrane and start to exude.