Yellow fever: symptoms, causes and treatment
There are many diseases that exist and have existed in the world throughout history. Some of them, like 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 just a thing of the past: there are still many diseases with no known cure and with the potential to kill.
One of them has been generating outbreaks and epidemics in African and South American countries for centuries. It's about yellow fever, which we are going to talk about throughout this article.
- Related article: "The 16 most common mental disorders"
Yellow fever: description and symptoms
Yellow fever is known as 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 major epidemics.
Yellow fever, also known as black vomit disease, Siam disease or Barbados disease (where the first case occurred registered), receives its name from one of its most characteristic symptoms, jaundice caused by alteration of the liver and pancreas.
But this is not your only symptom: It is also common the presence of bleeding through the mouth, ears or eyes, internal bleeding, very high fevers, headaches, arrhythmias, hypoglycemia and if intoxication phases are reached, in addition to the above, seizures, liver failure and kidney problems, even more severe bleeding, black vomit due to expulsion of clotted blood, bradycardia, dehydration, delusions or eat. 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 milder ones, the disease is self-limiting and does not enter its most serious phase with the potential for death.
Infection phases
Yellow fever is a dangerous disease. The infection involves going through a series of phases in which the symptoms and the severity of the condition vary, although not all people go through the last one. 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
From the moment the bite that transmits the virus that causes it occurs until the appearance of the first symptoms usually takes between three and six days. during them the virus is spreading through the body, without presenting any symptoms for 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, soft tissue redness, hot flushes, lack of appetite and jaundice.
- You may be interested in: "The 11 types of headache and their characteristics"
Phase 2. Remission
As a general rule, after several days of suffering from the symptoms described above, these usually end up remitting, disappearing little by little. In many cases the disease can be stopped at this stage, and the subject will recover. However, in others, the person may suffer a relapse and worsen 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 the fever reappears and symptoms such as bleeding from the mouth, nose and eyes may also occur. They also often have problems including 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 its name to the skin disease. The presence of pain in the abdomen, nausea and vomiting are also frequent.
It is also not uncommon for arrhythmias or bradycardia to occur. At the brain level, in addition to fever, hallucinations and delusions, confusion states and brain dysfunctions may appear. The subject may also have seizures or go into a coma. In short, they usually occur multi-organ failure and major bleeding.
Unfortunately, around the people who get to 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, the product of infection with the yellow fever virus, which, like dengue fever, belongs to the Flavivirus genus.
this virus reaches humans through the bite of infected mosquitoes, usually of the genera Aedes or Haemagogus. The virus can be transmitted between monkeys and from monkey to human by mosquitoes in what is known as the sylvatic ecological cycle or between people in the urban ecological cycle.
There is also a combined cycle of the two previous ones, that of the sheet, in which infected mosquitoes after biting apes transmit the disease to a human and then after other mosquitoes bite this one they transmit it to other people.
yellow fever not spread by contact with an infected person, nor with their 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 support treatments. It is essential the monitoring and maintenance of vital signs, dialysis in case of renal failure and fluid administration to maintain hydration and electrolyte balance. In addition to this, the use of antipyretics to reduce fever and antibiotics (not for the virus but for possible bacterial infections that may appear during it) can be very useful.
Despite the fact that 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 disease is endemic and get vaccinated in the case of traveling to those countries. Another measure is based on the control of the mosquito population, a measure that has been shown to be 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 (except high-risk situation), under 9 months of age and over 60 years of age (also unless there is a high risk) and immunosuppressed or allergic subjects to eggs and derivatives.
There are currently several initiatives to control yellow fever, such as the EYE program organized by the cooperation between the World Health Organization, UNICEF and Gavi-alliance for vaccines. This program aims to protect, prevent and control possible outbreaks of fever through participation in vaccination campaigns, research, health promotion and interaction with local institutions and administrations.
Bibliographic references:
- World Health Organization. (2014).Yellow fever. Small bites big threats.
- Soteras, E. (s.f.). Yellow fever. World Health Organization [Online]. Available in: http://www.who.int/es/news-room/fact-sheets/detail/yellow-fever.