Diphtheria is a serious bacterial infection primarily affecting the respiratory tract, caused by *Corynebacterium diphtheriae*. The signs of diphtheria typically begin to appear within 2 to 5 days after exposure and can range from mild to severe, depending on the progression of the disease and the body’s response to the diphtheria toxin.
At the onset, the most common early signs include a **sore throat**, which may feel scratchy or painful, often accompanied by a **mild to moderate fever** and general feelings of **fatigue and weakness**. People may also experience **chills** and a **loss of appetite**. One of the early physical signs is the swelling of lymph nodes in the neck, sometimes causing the neck to appear enlarged or swollen, a condition often referred to as a “bull neck.”
As the infection advances, a hallmark sign of diphtheria becomes apparent: the formation of a **thick, grayish-white membrane** that adheres firmly to the mucous membranes of the throat, tonsils, or nose. This membrane is composed of dead cells, bacteria, and fibrin, and it can cover the tonsils and pharynx, sometimes extending to the nasal passages or larynx. This membrane is not easily removed and can cause significant discomfort and obstruction.
The presence of this membrane can lead to **difficulty swallowing** and **hoarseness** or a distinctive **barking cough**. Breathing may become labored or rapid, and in severe cases, the airway can become blocked, leading to respiratory distress. This can cause the skin to take on a bluish tint due to lack of oxygen (cyanosis). Excessive drooling and swelling of the neck tissues are also common in more severe cases.
Beyond the respiratory symptoms, diphtheria toxin can spread through the bloodstream and cause systemic effects. One of the most dangerous complications is **toxic myocarditis**, an inflammation of the heart muscle that usually develops in the second or third week after infection. This can lead to irregular heart rhythms and heart failure if untreated.
Neurological complications may appear later, typically between the third and eighth week after the initial illness. These include **paralysis of the palate**, which affects swallowing and speech, and paralysis of some eye muscles. In more severe cases, paralysis can extend to the muscles involved in breathing and swallowing, which can be life-threatening. Limb paralysis may also occur but is generally less severe and not fatal.
There is also a form of diphtheria called **cutaneous diphtheria**, which affects the skin rather than the respiratory tract. This form presents as a sore or ulcer covered by a gray membrane, often occurring in people living in crowded or unhygienic conditions. While cutaneous diphtheria is usually less severe than respiratory diphtheria, it remains contagious and can contribute to the spread of the disease.
In summary, the signs of diphtheria start with mild symptoms like sore throat, fever, and fatigue, progress to the characteristic gray membrane in the throat and swollen neck glands, and can advance to serious complications including breathing difficulties, heart inflammation, and nerve paralysis. Early recognition of these signs is critical for timely treatment and prevention of severe outcomes.
