Yellow fever is a serious viral disease transmitted by the bite of infected mosquitoes, mainly of the genus Aedes, the same transmitters of other diseases such as dengue, Zika, and chikungunya. This disease is particularly prevalent in tropical and subtropical areas. In Colombia, it is common in jungle and rural regions of departments such as Amazonas, Meta, Guaviare, Tolima, Chocó, and Sierra Nevada de Santa Marta, among others.

Why get vaccinated against yellow fever?

Yellow fever vaccination is essential if you live in or plan to visit tropical areas with known risk. This vaccine is highly effective, offering protective immunity from the tenth day after administration and reaching 99% protection after one month. The vaccination is permanent and does not require additional booster doses.

Signs and symptoms

Yellow fever can be mild or severe, with initial symptoms appearing three to six days after infection. These may include:

Initial phase (acute)

• High fever
• Severe muscle pain
• Headache
• Nausea or vomiting
• General fatigue

In most cases, these symptoms disappear within three or four days.

Severe phase (toxic phase) Only a small percentage develop this phase, usually one day after the initial symptoms improve, presenting:

• Relapsing fever
• Yellowing of the skin and eyes (jaundice)
• Dark or scant urine
• Nasal, gingival, or gastrointestinal bleeding
• Extreme weakness, dizziness, or confusion

Half of the people in this phase could die within two weeks without adequate medical care.

Who should get vaccinated?

The yellow fever vaccine is recommended for everyone aged 9 months to 59 years. There are specific restrictions in the following cases:

• People with immunodeficiency, including patients undergoing cancer treatment.
• Pregnant or breastfeeding women.
• People with severe allergies to eggs or vaccine components.
• Adults over 60 years of age should consult their doctor beforehand.

Additional preventive measures

In addition to getting vaccinated, follow these recommendations to prevent transmission:

• Eliminate sources of standing water in your environment, which can become breeding grounds for mosquitoes.
• Use effective repellents. Use them regularly according to the product instructions and check that they are safe for your health.
• Wear long-sleeved clothing and long pants, especially outdoors or in wooded areas.
• Install mosquito nets on doors and windows.
• Avoid contact with wild animals, particularly if they are dead or sick, and report immediately to local health authorities.

Treatment

There is currently no specific antiviral treatment for yellow fever. Affected individuals should:

• Maintain complete rest.
• Stay properly hydrated.
• Seek immediate medical attention for any suspicious symptoms.

Seriously ill patients will require specialized medical care to manage complications such as internal bleeding or organ failure.

Key recommendations

• Do not self-medicate with antibiotics, painkillers such as aspirin, or any other medication without medical advice, as this could worsen your clinical condition.
• Avoid alcoholic beverages, tobacco, energy drinks, or foods high in fat and salt.
• Do not use intramuscular medications during the course of the illness.
• Avoid alternative treatments that are not medically approved during infection.
• Consult your doctor if symptoms persist or do not improve.

Updated diagnosis

Early detection of yellow fever is mainly carried out using molecular tests such as polymerase chain reaction (PCR), which allows the genetic material of the virus to be identified during the acute phase of infection (first 3 to 10 days). In later stages, when viremia decreases, serological tests such as ELISA or plaque reduction neutralization test (PRNT) are used to detect specific IgM and IgG antibodies against the virus. These tests help confirm infection when it is no longer possible to detect the virus directly.