What is Dengue? Dengue explained, Transmission, Symptoms, Risk Factors, Investigations.

Dengue is a mosquito-borne and pandemic-prone viral infection prevalent in many parts of the world.

Virus

Dengue is caused by a virus belonging to Flaviviridae family of which there are 4 distinct serotypes: DENV 1, DENV 2 DENV 3, and DENV 4. It’s important to have knowledge of these serotypes because recovery from a dengue infection will provide lifelong immunity against that serotype only. Subsequent infections from other serotypes will increase the risk of developing severe diseases.

Transmission

The virus is spread via the bite of a mosquito, mostly be Aedes aegypti and to a lesser extent, by Aedes albopictus mosquito. Important to note here is the fact that these very same mosquitoes are involved in the spread of other viral diseases, including Chikungunya and Zika. The mosquito can become infectious when it bites an infected individual. It then carries the Dengue virus and injects them into another individual during its next meal. Dengue doesn’t spread directly from one patient to the next. These mosquitoes can typically be found laying eggs in standing water in containers that hold water like buckets, bowls, animal dishes, etc. The incubation period of Dengue is 4-10 days once the mosquito has bitten the individual.

Symptoms

Dengue can cause a vide range of symptoms in a patient, from a subclinical disease in which the patient might be unaware of the infection to a severe infection in which the patient exhibits severe flu-like symptoms.
• The symptoms of Dengue include: High grade fever around 40′ C or 104′ F, along with nausea,
• Vomiting, which is generally non-billious,
• Rash,
• Aches and pains typically the area behind ghs eye which is termed as retro-orbital pain,
• Severe headaches,
• Generalized muscle pain and joint pains.
In case of a mild encounter, the patient will recover in about a week. In some cases however symptoms can worsen and become life threatening. Blood vessels become affected adversely and eventually get leaky. The clot forming platelets in the blood decrease in number which leads to jncreased susceptibility of the patient to bleed. This situation is known as Severe Dengue or Dengue Hemorrhagic Fever.

This is characterized by:
• Severe abdominal pain,
• Persistent vomiting, at least 3 times in 24 hours,
• Bleeding from the patient’s nose, called epistaxis,
• Bleeding from gums,
• Bleeding under the skin which appear like a purplish bruises,
• Feeling tired and restless,
• Blood in urine, also known as hematuria,
• Blood observed in stool and vomit
• And eventually the patient can slip into shock, they may have cold, clammy skin, tachyon and hypertension.

Risk Factors

Factors like living in or traveling to tropical areas can increase one’s risk of exposure to this virus. The more high-risk areas include Southeast Asia, the western Pacific Islands, Latin America and the Caribbean. Prior infection with a Dengue fever virus can result in a severe episode of disease with a high probability of developing Dengue Hemorrhagic Fever.

Investigations

Detailed Investigations need to be carried out if the patient exhibits symptoms of Dengue, and has the aforementioned risk factors. DENV infections can be confirmed by employing virological tests that detect the virus or their elements, or serological tests that detects the substances in our body during the infection. The examples of virological methods include:
1. Virus Isolation- The patient blood is taken to be grown inside the mosquitoes or their cells. After two weeks, the presence of the virus in the animal’s blood indicates the virus infection.
2. Reverse Transcriptase-Polymerase Chain Reaction or RT-PCR methods- The purpose I to multiply the viral RNA by using enzyme, several cycle times until it can be detected. In general, these tests are sensitive, but they require specialized equipment and technical training for implementing the test, which might not be always available in all medical facilities.

The examples of serologival methods are:
1. NS1 detection- NS1 is a protein produced by the cells that are infected by the DENV.
2. Enzyme-Linked Immunosorbemt Assays or ELISA- It detects the antibodies that are produces by pur body to fight the viruses.

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