DENGUE FEVER

Dengue fever tropical disease is a mosquito-borne disease which is caused by the dengue virus. The disease develops into a more severe dengue hemorrhagic fever in a small proportion of cases, resulting in bleeding, low blood platelets, and blood plasma leakage, or into dengue shock syndrome, where perilously low blood pressure occurs.

Dengue is spread by numerous species of female mosquitoes, i.e., the Aides genus and principally Aides aegypti. Various kinds of tests exist to confirm the diagnosis, including detecting antibodies to the virus or its RHA.

The dengue fever vaccine has been approved and is available in many countries commercially. Instead of non-steroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen) is recommended for fever reduction, control, and pain relief in dengue fever due to an augmented risk of bleeding from NSAID use.

SIGNS AND SYMPTOMS

People infected by dengue virus are mostly asymptomatic (80%) or have only mild symptoms, such as a mild fever. Therefore, travelers who are returning from endemic areas are unlikely to have this fever if symptoms start more than 14-days after arriving home. Often, children experience symptoms like those of a common cold and gastroenteritis (vomiting and diarrhea) and have a considerable risk of severe complications, though initial symptoms are generally mild but include high fever.

The specific dengue symptoms are sudden-onset fever, headache (typically located behind the eyes), muscle and joint pains, and a rash.

A rash occurs in 50-80% of those with symptoms on the first or second day of symptoms of dengue fever as flushed skin, or later on the course of the illness (days 4-7), as a rash like measles. Shock (dengue shock syndrome) and haemorrhage (dengue shock syndrome) and haemorrhage (dengue hemorrhagic fever) occur in less than 5% of all cases of dengue. The consciousness decreased level occurs in 0.5-6% of severe cases, which is attributable either to brain inflammation by the virus or indirectly to impairment of vital organs, for example, the liver.

In the context of dengue, other neurological disorders have been reported, such as transverse myelitis and Guillain-Barre syndrome.

DIAGNOSIS

The diagnosis is made clinically, on the basis of symptoms and physical examination. A probable diagnosis is based on the result of a fever plus nausea and vomiting, rash, widespread pain, low white blood cell count, and tourniquet test or any warning sign (see table) in people living in endemic parts of the world. It can be difficult to discriminate between dengue fever and chikungunya, a similar viral infection that shares many symptoms and occurs in the world. The investigations are performed to exclude other conditions that cause similar symptoms, such as malaria, viral hemorrhagic fever, measles, and influenza. The symptoms of dengue are also similar to those of Zika fever.

The earliest change noticeable is laboratory investigations in a low white blood cell count, followed by low platelets and metabolic acidosis.

CAUSE

Dengue fever virus (DENV) belongs to an RNA virus of the family Flaviviridae. Other members of this genus include the yellow fever virus, West Nile virus, Zika virus, St. Louis encephalitis virus, Japanese encephalitis virus, and Omsk hemorrhagic fever virus. Some are transmitted by arthropods (mosquitoes or ticks), and are referred to as arboviruses (arthropod-born viruses).

The dengue virus genome comprises about 11,000 nucleotide bases, which code for the three different kinds of protein molecules that form the virus particle and seven other non-structural protein molecules that are found in infected host cells only and are required for replication of the virus.

During the initial 2 to 10 days feverish period, a female mosquito takes a blood meal of a dengue fever infected patient and becomes infected with the virus in the cells lining its gut.

While each serotype can cause the full spectrum of disease, the virus strain is a risk factor.

Dengue can be life-threatening for patients with chronic diseases such as diabetes and asthma.

Polymorphisms in particular genes have been linked with an increased risk of severe dengue complications.

PREVENTION

The WHO (World Health Organization) recommends an Integrated Vector Control Program that includes five elements: Advocacy, social mobilization, and legislation to ensure that communities and public health bodies are reinforced. Collaboration between all the sectors, i.e. health and other public and private sectors. To maximise the use of resources is an integrated approach to disease control. Making decisions on evidence-based methods to ensure any interventions are targeted appropriately. Because of climate change, the range of this disease appears to be expanding. A partially effective vaccine against dengue fever was commercially available in 2016 in the Philippines and Indonesia. The vaccine named Dengvaxia is produced by Sanofi. The ideal vaccine is safe, effective in one or two injections, covers all serotypes, does not contribute to ADE, is easily stored and transported, and is both affordable and cost-effective.