NSCC: BIO110 – Introduction to Microbiology
Name of Pathogen: Bacterium Corynebacterium diphtheria
Body system affected: Respiratory tract, skin and lining tissues in the ear, eye, and the genital areas.
If Bacterial: Morphology: Slender pleomorphic rods; often club-shaped
If Bacterial Gram Stain: Gram positive
Reservoir: Humans are thought to be a significant reservoir for Corynebacterium diphtheria. It is only found in the mouth, throat, nose, skin, bodily secretions, and wounds of infected persons. Animals do not easily contract Diphtheria from human beings, and naturally have immunity.
Mode of Transmission: Can survive only in human beings. Diphtheria spreads by sneezing, coughing from an affected person to a susceptible patient, from person to
person through close contact with the discharge from an infected person's eyes, nose, throat or skin. The peak incidence is during autumn and winter. The disease is highly infectious and patient remains infected with ability to transmit the germ for two weeks or more.
Infective Dose: Toxin
Incubation Time: The incubation period (the time it takes for a person to become infected after being exposed) for diphtheria is 2 to 4 days, although it can range from 1 to 6 days.
Symptoms of Illness: Diphtheria disease has many sign and symptoms, however in some cases there may be no symptoms. Symptoms usually occur 1 to 7 days after the bacteria enter your body
Respiratory Diphtheria symptoms:
Adherent membrane of the tonsils, pharynx, or nose
Enlarged neck lymph nodes
Cutaneous Diphtheria symptoms:
Infected skin lesions
Red skin rash
With the progression of respiratory diphtheria, the infected individual may also develop an adherent gray membrane that is formed over the lining tissues of the tonsils or nasopharynx. This membrane also called pseudomembrane is dead tissue that develops from the effects of the diphtheria toxin. Individuals with severe disease may also develop neck swelling and enlarged lymph nodes of the neck, leading to a "bull-neck" appearance. Extension of the pseudomembrane into the larynx and trachea can lead to obstruction of the airway with subsequent suffocation and death.
Duration of Illness: Untreated patients who are infected with the diphtheria germ may be contagious for up to four weeks. If the patient is treated appropriately, the contagious period can be limited to less than four days.
At Risk Population: Anyone can get diphtheria, but it is extremely unlikely if you have been fully vaccinated. Diphtheria is more common in some countries with poor vaccine uptake, especially in Africa, South Asia and the former Soviet Union, so it is important to make sure your vaccinations are up to date if you are travelling to these areas.
People who are at increased risk of contracting diphtheria include:
Children and adults who don't have up-to-date immunizations
People living in crowded or unsanitary conditions
People who have a compromised immune system
Anyone who travels to an area where diphtheria is endemic
Number of cases for year: In the 1920s between 100,000 and 200,000 people became infected with diphtheria each year in the USA, causing up to 15,000 deaths annually. Most of the infections and fatalities were among children. Between the years 2000 and 2007 there were only 5 reported cases of diphtheria in the whole of the USA. Today, most children are vaccinated against this disease by...
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