What are the symptoms of plague infection?

The incidence of plague has been relatively low in recent years. It is an infectious disease transmitted by Yersinia pestis. Once a person becomes ill, he or she will develop a fever and suffer from severe symptoms of toxemia. It can cause swollen lymph nodes, severe pneumonia, bleeding, etc. It has been epidemic many times before liberation and had a relatively high mortality rate. In recent years, with the improvement of sanitary conditions, the incidence of this disease has become very low.

Clinical manifestations

1. Incubation period

The glandular type lasts 2 to 8 days; the pulmonary type lasts from several hours to 2 to 3 days; for those who have been vaccinated, it may be extended to 9 to 12 days.

2. Symptoms and signs

(1) Mild type with irregular low fever

The systemic symptoms are mild, with local lymph node swelling and pain, occasional suppuration, and no bleeding. They are more common in the early and late stages of an epidemic or in vaccinated people.

(2) Glandular type is the most common

It often occurs at the beginning of an epidemic. Sudden onset of chills, high fever, headache, fatigue, body aches, and occasional nausea, vomiting, irritability, skin bruises, and bleeding. When the disease occurs, the lymph nodes in the drainage area of ​​the flea bite are swollen and painful, which develops rapidly and reaches a peak on the 2nd to 4th day. The inguinal lymph nodes are most commonly affected, followed by the axillary, cervical, and submandibular lymph nodes. Due to the severe inflammation of the lymph nodes and surrounding tissues, the patient is in a forced position. If not treated promptly, the swollen lymph nodes will quickly become purulent and rupture, leading to death within 3 to 5 days from severe toxemia, secondary pneumonia or sepsis. If the patient is treated promptly or the condition is mild, the swelling will gradually disappear or the wound will heal and the patient will recover.

(3) Pulmonary type can be primary or secondary to glandular type

More common during epidemic peaks. Pneumonic plague develops rapidly, with sudden onset of high fever and obvious symptoms of systemic poisoning. Chest pain, cough, and sputum appear a few hours after the onset of the disease, and the sputum quickly turns from a small amount to a large amount of bright red bloody sputum. Dyspnea and cyanosis rapidly worsen. Moist rales can be heard in the lungs, breath sounds decrease, and signs and symptoms are often disproportionate. Those who are not rescued in time will die of heart failure or shock within 2 to 3 days. Before death, the patient becomes highly cyanotic and the skin often turns black and purple, hence the name Black Death.

(4) Sepsis can be primary or secondary.

The primary disease develops extremely rapidly, with severe symptoms of systemic toxemia, central nervous system symptoms and bleeding. The patient quickly enters unconsciousness, delirium or coma, and if not promptly treated, death usually occurs within 24 hours to 3 days.

(5) Other rare types

① Painful erythema appears at the site of skin flea bites, which quickly form blisters and pustules that may be mixed with blood and may form boils and carbuncles. The surface is covered with black scabs, surrounded by dark red, and has hard ulcers at the bottom, which is quite similar to cutaneous anthrax. Occasionally, a systemic herpes rash occurs, resembling smallpox or chickenpox. ② Eye-type bacteria invade the eyes, causing conjunctival congestion, swelling and pain, and even forming purulent conjunctivitis. ③ Throat-type bacteria invade through the mouth, causing acute pharyngitis and tonsillitis, which may be accompanied by swollen cervical lymph nodes. It may be an asymptomatic latent infection, but plague bacteria can be isolated from pharyngeal secretions through culture, most of which occur in people who have received vaccinations. ④ In addition to systemic symptoms, enteritis type also includes vomiting, abdominal pain, diarrhea, tenesmus and mucus in the stool, and the pathogen can be detected in the feces. ⑤ The meningitis type can be primary or secondary, with obvious symptoms of meningeal irritation. The cerebrospinal fluid is purulent, and plague bacteria can be detected by smear and culture.