Symptoms of dengue fever

Dengue fever is caused by any of four closely related Flaviviruses, DEN-1, DEN-2, DEN-3 and DEN-4.

These viruses are transmitted to humans by the Aedes aegypti mosquito, a domestic, day-biting mosquito that refers to feed on humans.

Dengue fever is known for having a variety of symptoms all of which happen after a sudden high fever.

The fever ranges from 38.8°C to 40.5°C and it may last for two to seven days.

Undifferentiated fever, accompanied by a rash, is an outcome of dengue infection more common among infants and young children.

Older children and adults are more likely to suffer the classical symptoms of dengue fever include:
*severe headache
*backache
*joint pain
*nausea and vomiting
*mild sore throat
*eye pain
*full body rash, including face, hands and feet
*general weakness

Dengue fever may be confused with Colorado tick fever, typhus, yellow fever, or other hemorrhagic fevers. In dengue fever, leukopenia usually present by the second day of fever.

By the fourth day or fifth day, white blood cells have dropped to 2000-4000/FL, with only 2-40% granulocyte.

The bleeding complications that sometimes accompany classical dengue during epidemics are differentiated clinically from those of dengue hemorrhagic fever.
Symptoms of dengue fever

Dengue fever

Dengue fever outbreaks have been documented on every continent except Antarctica. Dengue fever is transmitted to humans by the being of an infected mosquito.

Transmission means the virus is being passed or spread to someone else. Dengue virus (DEN) is a small single-stranded RNA virus comprising four distinct serotypes (DEN-1 to -4).

These closely related serotypes of the dengue virus belong to the genus Flavivirus, family Flaviviridae. There are three major illness caused by Flaviviridae: tick-borne encephalitis virus, Japanese encephalitis and dengue fever.

The various serotypes of the dengue virus are transmitted to humans through the bites of infected Aedes mosquitoes, principally Ae, aegypti.

This mosquito is a tropical and subtropical species widely distributed around the world mostly between latitudes 35 °N and 35 °S.

Dengue hemorrhagic fever is a severe often fatal, febrile disease caused by dengue viruses characterized by abnormalities of hemostasis and capillary permeability that leads, in severe cases, to a protein-losing shock syndrome.

A person can get dengue fever four times in his or her lifetime, although a person never gets the same dengue infection twice.
Dengue fever

A Historical Perspective of Dengue

A historical Perspective of Dengue
The story of dengue in many ways starts in the Americas.

Dr. Benjamin Rush made the first good clinical description of dengue.

He was in charge of hospitals under General George Washington in the Oriental Army and described for dengue outbreak in Philadelphia in 1780:

“This fever generally came on with rigor, but seldom with a regularly chilly fit. The pains which accompanied this fever were exquisitely severe in the head, back and limbs.

The pains in the head were sometimes in the back parts of it, and at other times they occupied only the eyeballs.

A few complained of their flesh being sore to the touch, in very part of the body. Its general name among all classes of people was the break-bone fever.”

Dengue today presents with the same fever, headache, eye pain, myalgia and arthralgia.

The US military’s dengue research efforts started just after the Spanish-America War, sparked by the very many dengue causalities in the Philippines.

A dengue commission was established in 1900, and Ashburn and Craig were sent to the Philippines to determine the etiology of dengue and to devise countermeasures.

Although a series of experiments they deduced that dengue was caused by “an ultra microscopic and non-filterable agent,” or a virus.

Ashburn and Craig confirmed that virus could be transmitted from person to person by both mosquito and by syringe; they made careful description of the disease to include leucopenia.

Important for vaccine development, they demonstrated that immunity following infection was absolute; they could only make healthy volunteers with dengue one time.

During World War II, Japan and the United States of America had large dengue research programs.

Dr. Hotta and Dr. Kimura in Japan isolated the dengue serotype 1 virus (DENV-1) shortly before Dr. Sabin and Dr. Schlesinger did so in Hawaii.

In the 1950s, the face of dengue changed dramatically with the widespread recognition of DHF. The army and the Air Force sent Dr. Bill Hammond to investigate the 1956 outbreak of hemorrhagic fever in the Philippines.

He worked with Philippines and Thai scientist to isolate DENV-3 and DENV-4.

The most important pathological process that distinguished DHF from dengue is plasma leakages that can lead to shock and death.

Untreated, DHF has a mortality rate of around 10%. With careful fluid management, however, mortality rates drop to below 1%.

DHF can occur in any age group, but it is most common among children living in dengue hyperendemic areas.
A historical Perspective of Dengue

Dengue Infection

Dengue Infection
Family: Flaviviridae
Genus: Flavivirus

Dengue is a mosquito born infection that has become a global public health concern in recent years.
Major epidemics of dengue have occurred in the Caribbean, South America, the Pacific, Asia, and Africa.

Dengue is a powerful health concern in many countries, especially in areas with urban slums and breeding places for mosquitos. The power of the virus is increased by that fact that at the present time, prospects for control are poor.

Dengue is caused by one of four closely related, but antigenically distinct, virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4). Infection with one of these serotypes does not provide cross-protective immunity, so people living in a dengue-endemic area can have four dengue infections during their lifetimes.

Dengue is transmitted through the Aedes aegyptia, a domestic day biting mosquito common in the tropics. The incubation period is about two to seven days. Infection with dengue viruses produces a spectrum of clinical illness ranging from a nonspecific viral syndrome to severe and fatal hemorrhagic disease. The three clinical profiles include dengue fever, dengue hemorrhagic fever, and dengue shock syndrome.

Dengue fever is a painful but non lethal syndrome characterized by rash, sudden onset of fever, severe headache, and other flu-like symptoms. Dengue hemorrhagic fever results in fluid loss through leaky blood vessels, leading to dyhydration, hypotension, severe jaundice, gastrointestinal hemorrhages and kidney failure.

This can sometimes worsen to dengue shock syndrome which is the most severe form of the disease in which a child can die of shock in hours. Important risk factors include the strain and serotype of the infecting virus, as well as the age, immune status, and genetic predisposition of the patient.

As shown by the doctrine of original antigenic sin, the body has the same immune response as its first infection, even if this is not the appropriate response. This is the problem with dengue infections.

Dengue only causes serious problems such as hemorrhagic fever and shock syndrome during the second infection of a different strain of the dengue virus. Antibody dependent enhancement increases the ability for uptake of the dengue virus via Fc receptors, enhances virion replication, and therefore makes the second infection of a different strain of the dengue virus much more serous then the first strain. ?


Because of the lack of cross protection between the dengue viruses, it is necessary to develop a vaccine protecting against all four dengue serotypes. There is no licensed vaccine for dengue because none of them guard against all for strains of the virus.

The most common method for control is mosquito control, however it is hard to spray using insecticides because the Aedes aegypti live in places hard to reach with pesticides. Other problems with this methods is the appearance of pesticide resistant mosquitos. Control of mosquito breeding is possible by draining stagnant water supplies.
Dengue Infection