Reach for the Light

Health

Dengue

2006 Prof. Frank Hadley Collins, Dir., Cntr. for Global Health and Infectious Diseases, Univ. of Notre Dame This 2006 photograph depicted a female Aedes aegypti mosquito while she was in the process of acquiring a blood meal from her human host, who in this instance, was actually the biomedical photographer, James Gathany, here at the Centers for Disease Control. You’ll note the feeding apparatus consisting of a sharp, orange-colored “fascicle”, which while not feeding, is covered in a soft, pliant sheath called the "labellum”, which retracts as the sharp stylets contained within pierce the host's skin surface, as the insect obtains its blood meal. The orange color of the fascicle is due to the red color of the blood as it migrates up the thin, sharp translucent tube. The fascicle is composed of a pair of needle-sharp "stylets". The larger of the two stylets, known as the "labrum", when viewed in cross-section takes on the shape of an inverted "V", and acts as a gutter, which directs the ingested host blood towards the insect's mouth. As the primary vector responsible for the transmission of the Flavivirus Dengue (DF), and Dengue hemorrhagic fever (DHF), the day-biting Aedes aegypti mosquito prefers to feed on its human hosts. Ae. aegypti also plays a major role as a vector for another Flavivirus, "Yellow fever". Frequently found in its tropical environs, the white banded markings on the tarsal segments of its jointed legs, though distinguishing it as Ae. aegypti, are similar to some other mosquito species. Also note the lyre-shaped, silvery-white markings on its thoracic region as well, which is also a determining morphologic identifying characteristic.

This female’s abdomen had become distended due to the blood meal she was ingesting, imparting the red coloration to her translucent abdominal exoskeleton.

Dengue has become a global problem since the Second World War and is common in more than 110 countries, mainly in Asia and South America. Each year between 50 and 528 million people are infected and approximately 10,000 to 20,000 die. The earliest descriptions of an outbreak date from 1779. Its viral cause and spread were understood by the early 20th century. Apart from eliminating the mosquitos, work is ongoing for medication targeted directly at the virus. It is classified as a neglected tropical disease. Typically, people infected with dengue virus are asymptomatic (80%) or have only mild symptoms such as an uncomplicated fever.  Others have more severe illness (5%), and in a small proportion it is life-threatening. The incubation period (time between exposure and onset of symptoms) ranges from 3 to 14 days, but most often it is 4 to 7 days.  Therefore, travelers returning from endemic areas are unlikely to have dengue if fever or other symptoms start more than 14 days after arriving home.

Children often experience symptoms similar to those of the common cold and gastroenteritis (vomiting and diarrhea) and have a greater risk of severe complications, though initial symptoms are generally mild but include high fever.

When a mosquito carrying dengue virus bites a person, the virus enters the skin together with the mosquito’s saliva. It binds to and enters white blood cells, and reproduces inside the cells while they move throughout the body. The white blood cells respond by producing a number of signaling proteins, such as cytokines and interferons, which are responsible for many of the symptoms, such as the fever, the flu-like symptoms, and the severe pains. In severe infection, the virus production inside the body is greatly increased, and many more organs (such as the liver and the bone marrow) can be affected. Fluid from the bloodstream leaks through the wall of small blood vessels into body cavities due to capillary permeability. As a result, less blood circulates in the blood vessels, and the blood pressure becomes so low that it cannot supply sufficient blood to vital organs.

Furthermore, dysfunction of the bone marrow due to infection of the stromal cells leads to reduced numbers of platelets, which are necessary for effective blood clotting; this increases the risk of bleeding, the other major complication of dengue fever.

There are no specific antiviral drugs for dengue; however, maintaining proper fluid balance is important. Treatment depends on the symptoms. Those who are able to drink, are passing urine, have no “warning signs” and are otherwise healthy can be managed at home with daily follow-up and oral rehydration therapy. Those who have other health problems, have “warning signs”, or cannot manage regular follow-up should be cared for in hospital.

Treatment

So far there is no medication available to treat dengue. The only treatment doctors provide is the infusion of platelets but this only in the severe cases. Some herbal treatments have been tried in Pakistan and have worked in most cases. These are as follows:

  1. Give patient apple juice with lemon and keep giving it whenever the patient wants to drink something. Generally people are using half glass of apple juice and adding half glass of water. This has really worked for many patients in Islamabad and Rawalpindi;
  2. Take a small papaya leaf fresh from the tree. Wash it and cut in small pieces. Add half a glass of water and shake it in an electric mixer. The patient should drink it all at once. Give the patient same twice a day once in the morning and once in the evening.

These two things have helped many people.

May God keep everyone healthy and happy. Please spread the word around, may be this small act of your is helpful for someone. Bless all!

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