Dengue Fever

Dengue fever is a natural focal viral disease in which the patient:

• body temperature rises sharply;
• chills appear;
• headache and muscle pain;
• nausea is observed.

In a severe course of the disease, spontaneous bleeding and hemorrhage of internal organs appear, which can lead to death.

The concept of a natural focal disease suggests that the source of infection is in the body of sick animals, and the transmission of infection occurs with the help of an insect vector.

How is dengue fever transmitted?

The causative agent of this disease is a virus belonging to the group of arboviruses .

Arbovirus is the informal name for any virus that is transmitted by arthropod vectors.

The natural reservoir (place of accumulation of the pathogen) is infected animals, such as bats or monkeys, or a sick person.

The carriers are mosquitoes of the genus Aedes, which abound in regions with a hot and humid climate. Mosquitoes become infectious on the 8-12th day after the bite of a sick animal, and this ability remains with them for life.

What forms can the disease take?

Infection can occur in two forms, namely:

• classical;
• hemorrhagic.

The first is usually characterized by a relatively mild course, while the second form of dengue fever is characterized by a severe course of the disease, and its lethality is quite high.

To a more severe course of the disease are prone to:

• children under 2 years old;
• persons with reduced immunity;
• visiting citizens.

Dengue fever can be contracted more than once, and each subsequent infection is usually more severe than the initial one. This is a feature of the negative impact of the disease on the immune system.

How the infection develops

Incubation period

It is 3-12 days after the bite of an infected mosquito.

Symptoms of the classic form

Some patients have a short prodromal (pre-disease) period during which they report malaise and low-grade fever. In other infected people, the disease develops sharply against the background of good health.

Patients complain about:

• a sudden increase in body temperature to 39-41 ° C, accompanied by chills, severe headache, nausea and a complete lack of appetite;
• pain in the muscles and joints, which greatly impede movement.

Doctors examining a patient note:

• an increase in regional (capturing a limited area) lymph nodes;

• a paradoxical decrease in heart rate (usually with fever, the heart rate, on the contrary, increases);
• hyperemia of the pharynx (redness of the throat);
• injection of vessels of the sclera (single hemorrhages);
• characteristic polymorphic rash (spots, papules, vesicles, abundantly covering the entire surface of the skin), accompanied by itching and flaking.

On the 7-9th day, the symptoms begin to decrease. However, before the final recovery takes usually from 1 to 2 months. During this time, symptoms such as:

• joint and muscle pain;
• weakness;
• decreased appetite.

Symptoms of the hemorrhagic form

The hemorrhagic form of Dengue fever is characterized by a more severe course than the classical one. The main difference between the hemorrhagic form is the presence of spontaneous bleeding (nasal, gastrointestinal, pulmonary) and hemorrhages in the internal organs.

Allocate a hemorrhagic form with Dengue shock or with its absence.

Dengue shock syndrome manifests itself:

• tachycardia ;

Tachycardia is a rapid heartbeat, an abnormal heart rhythm when the heart rate (HR) per minute exceeds 90 beats.

• a sharp decrease in blood pressure;
• signs of circulatory disorders;
• convulsive syndrome.

Dengue Fever Diagnosis

There are specific WHO criteria for suspecting dengue fever in patients in endemic (certain) geographic areas. These include the characteristic clinical manifestations described above, in combination with a decrease in the number of platelets in the blood and an increase in hematocrit.

Hematocrit is the ratio of the volume of red blood cells to the volume of the liquid part of the blood. Determination of hematocrit is an integral part of the general blood test and is not performed separately.

The final diagnosis is confirmed:

• immunologically (when determining the increase in the titer of antibodies to the pathogen);
• molecular biological (PCR method for the isolation of virus RNA fragments in the patient’s blood).

Differential diagnosis of Dengue fever is carried out simultaneously with other tropical fevers, such as malaria and meningococcal infection. As well as measles and rubella in children.

Treatment

There is no specific drug against the causative agent of Dengue fever, so the treatment is carried out symptomatically using:

• antipyretics (to fight fever);
• detoxification agents ;

Detoxification agents are drugs that promote the release of toxins from tissues into the blood plasma and their excretion by the kidneys.

• antiallergic drugs;
• in hemorrhagic forms, hemostatic anti-shock measures are used.

Preventive measures

The main preventive measure in endemic areas is the destruction of vectors, namely:

• drainage of wetlands;
• the use of texicides (special preparations used to destroy harmful insects);
• the use of mosquito nets and fumigators in residential areas.

The question of vaccination against this serious disease is currently still open. A vaccine given to people who have not previously suffered from Dengue fever can, if it occurs, seriously aggravate the course of the disease.