There are many diseases that exist and have existed in the world throughout history. Some of them, such as the Black Death, were a plague that wiped out a high percentage of the world’s population. And the existence of serious diseases capable of causing pandemics is not only a thing of the past: there are still many diseases with no known cure and with deadly potential.
One of them has been generating outbreaks and epidemics in African and South American countries for centuries. It’s yellow fever which we are going to talk about throughout this article.
Yellow fever is one of the diseases classified as hemorrhagic fevers, which has caused and continues to cause hundreds of thousands of deaths each year. It is an endemic disease present mainly in African or South American areas, and that even today can lead to the emergence of major epidemics
Yellow fever, also known as black vomiting disease, Siam disease or Barbados disease (where the first recorded case occurred), gets its name from one of its most characteristic symptoms, jaundice caused by alteration of the liver and blood vessels. pancreas.
But This is not your only symptom: the presence of bleeding through the mouth, ears or eyes, internal bleeding, very high fevers, headaches, arrhythmias, hypoglycemia is also common, and if intoxication phases are reached, in addition to the above, seizures, liver and kidney failure may appear, even more severe hemorrhages, black vomit due to the expulsion of clotted blood, bradycardia, dehydration, delirium or coma. In severe cases it has a high potential to cause death, and it does so in a high number of cases.
In other cases, the mildest, the disease is self-limiting and does not enter its most serious phase with fatal potential.
Phases of infection
Yellow fever is a dangerous disease. The infection involves passing through a series of phases in which the symptoms and severity of the condition vary, although not all people go through the last of them. We can identify a total of three phases to which we could add a previous one in the form of an incubation period.
Phase 0: Incubation period
Between three and six days usually pass from the moment the bite that transmits the virus that causes it occurs until the appearance of the first symptoms. during them the virus is spreading through the body without presenting any symptoms at the moment.
Phase 1: Acute phase
Several days after the bite, a series of symptoms typical of an infection usually appear: high fevers, nausea and vomiting, photophobia, headache appear redness of soft tissues, hot flashes, lack of appetite and jaundice.
Phase 2. Referral
As a general rule, after several days of suffering from the symptoms described above, they usually end up subsiding, disappearing little by little. In many cases the disease can be stopped in this phase, and the subject recovers However, in others the person may suffer a relapse and worsen again about a day later, entering the intoxication phase.
Phase 3: Intoxication
After several days of remission, some of those affected by yellow fever enter a phase of intoxication in which symptoms reappear with great virulence This is the most serious phase of the disease.
During this phase, fever reappears and symptoms such as bleeding from the mouth, nose and eyes may also occur. They also often have problems or even kidney or liver failure In fact, it is in this phase of the disease that jaundice most often appears, giving the skin the yellowish color that gives the skin disease its name. The presence of pain in the abdomen, nausea and vomiting are also common.
Likewise, it is not uncommon for arrhythmias or bradycardia to occur. At the brain level, in addition to fever, hallucinations and delusions, states of confusion and brain dysfunctions may appear. It is also possible that the subject has seizures or goes into a coma. In short, they usually occur multi-organ failure and major bleeding
Unfortunately, around people who enter this phase (in a window that ranges between 25%-60%) do not manage to overcome the disease and die.
Causes of this disease
Yellow fever is a viral disease, a product of infection with the yellow fever virus, which, like diseases such as dengue, belongs to the genus Flavivirus.
This virus It reaches humans through the bite of infected mosquitoes, generally of the Aedes or Haemagogus genera. The virus can be transmitted between monkeys and from monkey to human by mosquitoes in what is known as the jungle ecological cycle or between people in the urban ecological cycle.
There is also a combined cycle of the two previous ones, the sheet cycle, in which mosquitoes infected after biting apes transmit the disease to a human and then after other mosquitoes bite this person, they transmit it to other people.
yellow fever It is not spread by contact with an infected person nor with its secretions.
Is there treatment?
Yellow fever is a disease for which even today there is no specific curative treatment. In case of infection, the intervention involves supportive treatments. It is essential monitoring and maintaining their vital signs, performing dialysis in case of kidney failure and administering fluids to maintain hydration and electrolyte balance. In addition, the use of antipyretics to reduce fever and antibiotics (not for the virus but for possible bacterial infections that could appear during it) can be very useful.
Although there is no cure per se, we do have an effective vaccine against yellow fever, and in principle a single dose is necessary to protect yourself for life. That is why the best way to treat yellow fever is to prevent it, being necessary establish vaccination programs in countries where this condition is endemic and get vaccinated if traveling to these countries. Another measure is based on controlling the mosquito population, a measure that has been proven effective in several countries.
However, the vaccine may be contraindicated or require medical evaluation prior to its application in some sectors of the population: pregnant women (unless there is a high-risk situation), children under 9 months of age and those over 60 years of age (also unless there is a high risk) and immunosuppressed subjects or those allergic to eggs and egg products.
There are currently several initiatives to control yellow fever, such as the EYE program organized by cooperation between the World Health Organization, UNICEF and Gavi-vaccine alliance. This program aims to protect, prevent and control possible fever outbreaks through participation in vaccination campaigns, research, health promotion and interaction with local institutions and administrations.
