MDB Series - Dengue Part 3

This post is third in the series about mosquito borne diseases.

Disclaimer: This post is for information purposes only. This is not written by any medical doctor or government official or anyone related to the worldwide research on mosquito borne diseases. Neither is this a complete information about dengue and should not be relied on for reference. However, we have taken care to refer to reliable sources on the web, the links to which would be provided at the end of the post.

Development

When an infected mosquito bites a human being, the dengue virus enters the blood stream via the mosquito’s saliva. The virus first binds to dendritic cells that have the ability to identify pathogens.  They replicate inside the cells and use cell proteins to multiply. They enter the white blood cells and continue to replicate as the cells move throughout the body through blood. Through the walls of small blood cells, fluid leaks into other body cavities, leading to less blood circulation. This leads to low blood pressure and as consequence there is no sufficient blood flow to vital organs.

When initially the virus attacks a cell, the white blood cells produce a protein called interferon, which cause the fever like symptom. As the blood flow decreases, it leads to dysfunction of bone marrow which further leads to low platelet count. Platelets are necessary to clot blood and arrest flow of bleeding. This is the cause of a severe form of dengue called dengue haemorrhagic fever.

Symptoms

Usually most dengue infected people don’t exhibit many symptoms. Sometimes there are mild generic symptoms like fever. Very few people have severe fever. The incubation period for this disease ranges from 3 to 14 days, but usually it is 4 to 7 days.

The following are the typical symptoms of dengue,

·         Fever

·         Rash and/or increased skin sensitivity

·         Fatigue

·         Headache

·         Nausea

·         Vomiting

·         Cough

·         Sore throat

·         Joint ache

·         Muscle inflammation

·         Nasal stuffiness

·         Swollen lymph nodes

·         Pain behind the eyes

·         Mild bleeding

Dengue per se is not fatal. However, when a high fever is accompanied by any of the above listed symptoms, dengue should be suspected as variations of this disease are fatal.

Variations

There are more severe versions of this disease. Dengue haemorrhagic fever causes bleeding and low levels of blood platelets, resulting in death most often.  Dengue shock syndrome is caused when the blood pressure drops to dangerously low levels. When a patient is infected a second time by dengue, they will have complications associated with the disease. 

Sources: Dengue Virus Net, WHO, WebMD, Wikipedia, Medindia, US National Library of Medicine, Ministry of Health and Family Welfare( Govt of India)