What is diphtheria, an acute respiratory infectious disease

Diphtheria is an acute respiratory infectious disease that causes symptoms such as tonsil congestion, irritability, nausea, high fever, and nasal congestion. Diphtheria has a certain incidence rate among young children and is highly contagious. Once infected, children must be isolated in a timely manner.

1. Pharyngeal diphtheria

Pharyngeal diphtheria is the most common, accounting for about 80% of the cases. According to the scope of the lesion and the severity of the symptoms, it can be divided into:

(1) Pharyngeal diphtheria without pseudomembrane: This is more common during diphtheria epidemics. Some patients may only have upper respiratory tract symptoms, such as sore throat, mild systemic poisoning symptoms, no fever or mild fever, and only mild inflammation in the pharynx. The tonsils may be swollen, but no pseudomembrane is formed, or only a small amount of fibrinous exudate is present. Bacterial culture is positive. Such patients are prone to misdiagnosis and missed diagnosis.

(2) Localized pharyngeal diphtheria

(3) Disseminated pharyngeal diphtheria: If localized patients do not receive timely and effective treatment, the pseudomembrane can spread to the uvula, soft palate, posterior pharyngeal wall, nasopharynx and larynx, and even the oral mucosa to become a disseminated type. This type is more common in young children. The pseudomembrane is large and thick, and can be grayish white, yellow, dirty gray or black. The mucosa around the pseudomembrane is red and swollen, the tonsils are obviously enlarged, the submandibular lymph nodes and cervical lymph nodes are enlarged and tender, and there may be edema around the lymph nodes. Patients of this type have obvious symptoms of systemic poisoning. The patient may have a high fever of 40°C, dizziness, headache, weakness, nausea, vomiting, and then circulatory failure. The patient is pale and has a weak and rapid pulse.

(4) Toxic pharyngeal diphtheria: This type can be transformed from localized and disseminated types, or it can be primary. There are often mixed infections, especially streptococcal infections. The pseudomembrane is extensive and is often black due to bleeding. The tonsils and pharynx are highly swollen, and the pharyngeal opening may be blocked or necrotic, forming ulcers and emitting a special foul odor. The cervical lymph nodes are swollen, and the surrounding tissues are edematous, causing the neck and even the tissues near the clavicle to swell, resembling a "bull neck". The patient has a high fever, irritability, rapid breathing, pale complexion, cyanotic lips, a thin and rapid pulse, and a drop in blood pressure. Some may have an enlarged heart and arrhythmias such as gallop rhythm. If not treated in time, most will die within 2 weeks.

2. Laryngeal diphtheria

Laryngeal diphtheria occurs in about 20% of patients, of which 1/4 are primary with no lesions in the pharynx, and 3/4 are caused by the spread of pharyngeal diphtheria downward. Primary pharyngeal diphtheria is more common in children aged 1 to 3 years old, manifested by "barking" cough, hoarseness or even loss of voice. Due to the presence of pseudomembranes in the larynx, trachea, etc., varying degrees of respiratory distress are caused, mainly manifested as inspiratory dyspnea. If the pseudomembrane extends to the trachea and bronchi, the respiratory distress is more serious. If endotracheal intubation or tracheotomy with tracheal cannula placement is not performed in time, the patient often dies within one or two days. Since the laryngeal and tracheal pseudomembranes are not firmly adhered to the mucosa, the tubular pseudomembranes can sometimes be coughed out or sucked out, and the respiratory distress can be relieved. Since the toxin is absorbed less, the symptoms of systemic poisoning are not serious.

3. Nasal diphtheria

This type is relatively rare and is more common in infants and young children. The main symptoms are nasal congestion, bloody and serous secretions, which do not heal for a long time. The periphery of the nostrils and the upper lip often form superficial ulcers covered with scabs due to the corrosion of the secretions. In simple vestibular diphtheria, the pseudomembrane may be located on one or both sides. The children have no fever or a slight fever, and often have breastfeeding disorders, mouth breathing, restless sleep, weight loss, etc. Secondary cases are mostly from pharyngeal diphtheria.

4. Diphtheria in other parts of the body

Corynebacterium diphtheriae can invade the conjunctiva of the eyes, ears, vulva of girls, umbilicus of newborns and skin injuries, and pseudomembranes and purulent secretions will appear in different parts of the body. Diphtheria of the eyes, ears and vulva is mostly secondary. Cutaneous diphtheria is common after skin trauma, often accompanied by mixed infection. The pseudomembrane is yellow or gray, and may have necrosis and ulceration. Nearby lymph nodes may swell. Skin lesions often do not heal for a long time, and melanin deposition may occur after healing. Patients rarely have symptoms of systemic poisoning, but peripheral nerve paralysis may occur. The incidence of cutaneous diphtheria is not high, but it has increased significantly in some areas and is more common in tropical areas.