What is dengue fever?

Dengue is a viral disease transmitted by the Aedes aegypti and Aedes albopictus mosquitoes, which only bite during the day, unlike the common Culex, which always attacks at night.

The disease occurs mainly in tropical and subtropical areas of the world and occurs in summer, during, or immediately after rainy periods. Sudden onset, dengue evolves benignly when treated correctly.

Most people improve after about five days, recovering completely within ten days. However, in some cases, classic dengue can give way to dengue hemorrhagic fever, which is the most severe form of the infection, evolving, among other complications, with a marked drop in blood pressure. This hypotension requires immediate medical attention, as it can lead to shock.

The most important forms, either by frequency or severity, are:

  • Classic dengue: this is the most common and causes fever, headache, malaise and muscle pain;
  • Dengue hemorrhagic fever: starts like the classical form, but after three to five days the fever goes down. After two days of absence, fever returns, accompanied by hemorrhagic manifestations on the gums and skin and severe abdominal pain;
  • Dengue shock syndrome: begins like the classic form, but after three or four days the patient develops with low blood pressure, intense sweating and attention deficit due to low blood flow. This form is quite rare, especially in primary dengue (the first occurrence of dengue).
    It should be noted that the risk of dengue hemorrhagic fever only exists for those who have had a previous episode of the disease.

Causes and symptoms of dengue fever

The symptoms of dengue can be confused with those of numerous other diseases, such as leptospirosis, measles, rubella, and even influenza. Classic dengue manifests with high fever, headache, muscle pain, weakness and listlessness, joint pain and pain in the back of the eyes, nausea, vomiting, and body spots for about seven days. However, it is important to note that the intensity of symptoms varies depending on the individual response to the virus, and in some people, dengue can pass for the strong flu or other viruses without the correct diagnosis.

Dengue hemorrhagic fever starts in the same way as classical dengue, but its characteristic clinical signs appear when the fever begins to break: abdominal pain, symptoms indicating a drop in pressure such as cold sweats, dizziness, fainting, and cold skin, incessant bleeding (nose, gingival, urinary, gastrointestinal or uterine) and darkening of the stool, among others. Dengue is caused by an arbovirus that has four serotypes (1, 2, 3, and 4), all of which are capable of triggering infection with the same manifestations.

Each time the disease is contracted by one type of agent, immunity is gained against new infections caused by that type. Thus, each individual can have up to four episodes of dengue fever. Dengue hemorrhagic fever only occurs in individuals who have already had dengue and suffer a new infection, caused by a serotype different from the first.

This reinfection causes an exacerbated immune system reaction, which ultimately triggers hemorrhage. Dengue is not transmitted directly from person to person but always involves the mosquito as an intermediary. There is usually an interval of 2 to 15 days between the insect bite and the appearance of clinical signs.

Tests and diagnosis of dengue fever

The initial diagnosis of dengue is clinical, i.e. it is based on anamnesis and physical examination of the individual, and is made by exclusion of more serious diseases with similar symptoms. It is possible to confirm the virus with a test that analyzes the blood of the individual suspected of having the disease for the presence of antibodies against the arbovirus.

This test, however, is only positive on the sixth day after the onset of symptoms. A newer test, called PCR or molecular testing, can detect the virus in the patient’s blood earlier, allowing the physician to close the diagnosis more quickly and reliably and to quickly institute appropriate treatment.

Treatment and prevention of dengue fever

The treatment of classic dengue fever is usually done at home and includes oral rehydration of the individual, with homemade serum or solutions suitable for this purpose, as well as the use of antipyretics and analgesics to reduce fever and control pain.

Given the risk of hemorrhage associated with this infection, no over-the-counter medication should be taken when dengue is suspected, since many anti-inflammatory and analgesic drugs contain active substances that alter blood coagulation, favoring hemorrhages, as in the case of acetylsalicylic acid, present in Aspirin.

On the other hand, dengue hemorrhagic fever requires hospital admission for venous rehydration and continuous monitoring to avoid shock. The prevention of dengue necessarily involves the elimination of the transmitters, the mosquitoes. As Aedes aegypti is a domestic insect, living in or near houses, it is necessary to eliminate the places where the female lays her eggs. To do this, it is necessary to suppress any water collection.

In practice, it is recommended to put soil in flowerpots, clean roof gutters to avoid water accumulation, not expose objects that can store water to rain, pack the garbage in closed bags or containers, and close water tanks, among other measures.

As individual protection measures to avoid mosquito bites, the use of diethyltoluamide (Deet) repellents on exposed areas of the body, the application of insecticide in the home environment, the use of mosquito nets and mosquito nets, and the use of coils or electric vaporizers during the hours when mosquitoes bite the most: before dawn or late in the afternoon are recommended.