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Yellow fever - Symptoms.
Last reviewed: 04.07.2025
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The incubation period for yellow fever is usually 3-6 days (rarely up to 10 days).
Symptoms of yellow fever allow us to distinguish the following forms of the disease:
- light;
- moderate;
- heavy:
- lightning fast.
In typical cases, yellow fever has a two-wave course with three periods:
- initial febrile (hyperemia period):
- period of remission with a decrease in body temperature:
- period of venous stasis (reactive).
Yellow fever usually begins acutely without prodromal symptoms. High fever develops within the first 24 hours. The rise in temperature is accompanied by chills, muscle pain in the back and limbs, and severe headache. Nausea and vomiting occur.
Usually, the body temperature drops to normal values by the end of the 3rd day, but in severe cases, the fever can last 8-10 days. Then the temperature rises again, usually without reaching the initial high values. At the onset of the disease, the following symptoms of yellow fever occur: hyperemia of the face, neck and upper body, pronounced injection of the scleral vessels, swelling of the eyelids, swelling of the lips, puffiness of the face ("amarilla mask"). Photophobia and lacrimation are characteristic. The mucous membrane of the mouth and tongue are bright red. Patients suffer from insomnia. Nausea and vomiting with an admixture of bile appear. The pulse reaches 100-130 beats per minute, good filling; bradycardia develops later. Blood pressure is normal, heart sounds are slightly muffled. An enlarged liver and spleen are detected, they may be painful upon palpation. A general blood test reveals neutropenia and lymphopenia. ESR is not increased. Proteinuria is characteristic.
With the onset of yellowish staining of the sclera, conjunctiva and soft palate, arterial pressure decreases and cyanosis appears. The condition of patients significantly worsens. Nosebleeds, bleeding gums are possible, blood is found in the vomit. In severe cases of yellow fever, the patient may die during this period. In milder cases, a remission stage occurs, while the body temperature decreases to normal values, the general condition improves, nausea and vomiting stop, the face turns pale, and puffiness disappears. However, after a few hours, a sharp deterioration in the condition of patients occurs again, the body temperature quickly rises. These symptoms of yellow fever indicate the transition of the disease to the most severe period - venous stasis. observed in approximately 15% of patients and characterized by the development of jaundice, hemorrhagic diathesis and acute renal failure. Bleeding gums, as well as nasal, uterine and intestinal bleeding are detected. Hemorrhages occur against the background of a polymorphic rash on the skin. Vomiting of the color of coffee grounds often appears. Blood pressure drops; heart sounds are muffled: the pulse is weak in volume up to 40 per minute. The patient's condition is often aggravated by kidney damage; a decrease in diuresis is detected. Oliguria may be replaced by anuria: azotemia may develop. The amount of protein in the urine increases to 10 g / l and more, granular and hyaline casts appear. The level of urea and creatinine in the blood increases. The liver is slightly enlarged, painful. The amount of bound and free bilirubin increases, an increase in the activity of aldolase and aminotransferases is detected. The content of leukocytes decreases to 1.5-2.5x10 11 per liter of blood; neutropenia and lymphopenia occur. Blood clotting slows down, ESR increases. These changes are most pronounced on the 6th-7th day of the disease - a critical period for the patient.
With a favorable course of the disease, the general condition of patients gradually improves from the 8th-9th day. Clinical and laboratory parameters normalize. Asthenia persists for a week.
There are also possible forms of the disease in which symptoms of yellow fever are absent. The diagnosis is established retrospectively using serological research methods.
[ Mortality and causes of death
The fulminant form leads to death on the 3rd-4th day of the disease. Severe symptoms of yellow fever most often end in death on the 6th-7th day.
Death occurs with the development of acute renal, hepatic and cardiovascular failure. Symptoms of toxic encephalopathy are often detected.