Diphtheria is classified as a group B infectious disease with rapid transmission, epidemics, and high mortality rates. Infected people must be declared and quarantined.
Diphtheria is caused by the bacterium Corynebacterium diphtheriae (C.diphtheriae) which causes local and systemic disease by producing exotoxins that act locally, forming a membrane (pseudomembrane) that adheres firmly to the upper respiratory tract mucosa. The pseudomembrane is white then turns gray, thick, sticky, difficult to peel off, and bleeds easily when peeled off. After a few hours, it will grow back quickly. Exotoxins produced by C.diphtheriae enter the blood, causing damage to organ cells such as the heart, kidneys, and nerves.
Diphtheria bacteria are gram-positive (+) cocci, club-shaped, 1-9 µm long, 0.3-0.8 µm wide, non-motile, non-capsular, non-spore-forming. Diphtheria bacilli live long in pseudomembranes and throats of patients.
You asked how long diphtheria bacteria can live, it depends on weather and environmental conditions. They can live from a few hours to 16 months. This bacteria has high resistance outside the body, can withstand cold and dryness. If surrounded by protective mucus, the bacteria can live on objects for several days to several weeks, live for 30 days on fabrics and milk, 20 days in drinking water, two weeks in corpses. In general, in low light conditions, C.diphtheriae bacteria can live up to 6 months, survive for a long time on toys of children with diphtheria, gowns of medical staff…
Doctor Thuy Hau examines a patient with an infectious disease. Illustration photo: Tam Anh General Hospital
Diphtheria bacteria are sensitive to light and high temperatures. In direct sunlight, the bacteria die after a few hours. At 58 degrees Celsius, the bacteria can live for 10 minutes, and in a 1% phenol solution and 60-degree alcohol, they can live for about a minute. However, some healthy people can still carry the pathogen in their nose and throat for an average of 3-4 weeks, sometimes up to 16 months. Sharing household items, contacting surfaces contaminated with secretions from sick people or people carrying the pathogen, then touching the eyes, nose, and mouth can also easily transmit the bacteria.
Even healthy people can be carriers. Children and adults should receive diphtheria vaccination according to their schedule. Adults should receive a diphtheria booster every 10 years after the last dose at age 9-15 to strengthen their immunity.
Diphtheria is transmitted through the respiratory tract by direct contact with nasal and throat secretions from an infected person or a carrier. Another route of transmission is indirect contact with toys or objects containing secretions containing the bacteria.
You should keep your home, workplace, and study area clean, well-ventilated, and disinfect frequently touched objects. You should also wash your hands frequently with soap, cover your mouth when coughing or sneezing, and avoid contact with patients or people showing symptoms of illness.