What are the typical symptoms of yellow fever

Yellow fever often occurs in tropical areas. It is an acute infectious disease caused by the yellow fever virus. The main cause is the bite of a mosquito. Patients often experience symptoms such as high fever and headache. This disease is highly contagious and has a relatively high mortality rate. So far, there have been no reports of this disease in my country. It mainly occurs in Africa, South America and other regions.

The incubation period is 3 to 6 days. Most infected people have mild symptoms, which may only include fever, headache, mild proteinuria, etc., which last for a few days before recovery. Severe cases occur in only about 15% of cases. The course of the disease can be divided into 4 stages.

1. Infectious period

Sudden onset of high fever accompanied by chills, severe headache and body pain, obvious fatigue, loss of appetite, nausea, vomiting, diarrhea or constipation, etc. The patient is restless, has conjunctival congestion, and flushing of the face and neck. The heart rate parallels the fever and then turns to relative bradycardia. This phase lasts about 3 days, during which time the virus reaches high titers in the blood and becomes a source of infection for mosquitoes. Mild jaundice and proteinuria may occur at the end of the period.

2. Remission period

The fever partially or completely subsides, and symptoms improve, lasting from a few hours to 24 hours.

3. Poisoning period

Fever and symptoms return and become more severe. During this period, toxemia subsides, and liver, kidney, and cardiovascular function damage and bleeding symptoms appear. Serum bilirubin is significantly elevated, prothrombin time is prolonged, and the degree of proteinuria, oliguria and azotemia is proportional to the condition. The prominent symptoms of this stage are severe bleeding such as gingival bleeding, nose bleeding, skin and mucous membrane ecchymosis, gastrointestinal tract, urethral and uterine bleeding, etc. The heart is often enlarged, the heartbeat is slow, the heart sounds become weaker, and the blood pressure is low. It is often accompanied by dehydration and acidosis. In severe cases, delirium, coma, urinary retention, intractable hiccups, massive hematemesis, shock, etc. may occur. This phase lasts 3 to 4 days or 2 weeks. Death usually occurs between the 7th and 10th days.

4. Recovery period

The body temperature drops to normal. Symptoms and proteinuria gradually disappear, but fatigue may persist for 1 to 2 weeks or longer. The heart condition still needs to be closely monitored during this period. In some cases, death may occur due to arrhythmia or heart failure. Survivors generally have no sequelae.