The Dengue Fever
The Dengue Fever is an agonizing and crippling mosquito-borne disease that isn’t contagious. Is is transmitted by the bite of an Aedes mosquito that is infected with the Dengue virus. The mosquito gets infected when it bites a human that has already been infected by the Dengue virus. It is caused by four viruses, called DEN-1, DEN-2, DEN-3, and DEN-4. They are called serotypes because they all have distinctive interactions with the antibodies in the human blood serum, which is the portion of plasma that remains after the concentration of blood. The Dengue viruses share an estimated 65 percent of genome, but they vary in genes and even with their variations, the serotypes all result in the same disease and clinical indication of the virus. After recovering from an infection with a virus, the body builds up antibodies for that specific serotype. You are also temporarily protected from all the other serotypes for 2-3 months after you have recovered from the Dengue infection.
Worldwide, there are approximately 390 million Dengue infections that occur annually, with 96 million cases resulting in illness. Most cases appear in the tropical areas of the world, including greater risks in the Indian subcontinent, Southern China, Southeast Asia, Taiwan, Mexico, The Pacific Islands, Africa, the Caribbean, with the exception of the Cayman Islands and Cuba, and South and Central America, except Paraguay, Argentina, and Chile. In the United States, most cases are contracted while traveling abroad or near the Mexican border.
The Discovery of the Dengue Virus
DEN-1, DEN-2. DEN-3, and DEN-4 are members of the genus, Flavivirus, and are in the family, Flaviviridae. These are also called arboviruses. This genus includes a number of other viruses that are transmitted by the bite of a mosquito or tick and are responsible for human diseases. The first time that the Dengue Fever was isolated was in 1943 by Ren Kimura and Susumu Hotta. They were studying blood samples from the 1943 Dengue epidemic in Nagasaki, Japan. They isolated the serotype that is now called DEN-1. Another pair of scientists in 1944 independently isolated the Dengue Fever serotype DEN-1. They were named Albert B. Sabin and Walter Schlesinger. In the 1970s, DEN-1 and DEN-2 were found in Central America and Africa. All serotypes were found in Southeast Asia at the same time. In 2004, all serotypes shared the same geographical and ecological range. Scientists hypothesize that the virus developed in nonhuman primates and changed from primates to humans.
Symptoms, Diagnosis, and Treatment of the Dengue Virus
The symptoms of the Dengue virus usually begins four to six days after the infection and lasts up to ten days. The symptoms include sudden, high fever, severe headaches, pain behind the eyes, severe joint and muscle pain, fatigue, nausea, vomiting, a skin rash that appears two to five days after the starting of the fever, and mild bleeding, such as nosebleeds, bleeding gums, or easy bruising. The Dengue Fever symptoms can be mild and be mistaken the symptoms of the flu or other viral infections. People who are just encountering the virus for the first time and younger children usually have mild cases compared to those of older children and adults. To diagnose Dengue Fever, a doctor will check for the Dengue virus and the antibodies to the virus by a blood test.
There are no medicines that are specific to treat the Dengue infection, so all the methods that are used, are aimed at lightening and controlling the symptoms while aiding the body heal naturally. The methods include hydration of intravenous or IV fluids, electrolyte therapy, blood transfusions, careful monitoring of blood pressure, oxygen therapy, observation, and painkillers that have acetaminophen. They avoid painkillers with aspirin because it would worsen any bleeding that could be happening in the body. Severe Dengue cases often are more difficult to treat because the symptoms are worse and arise at a faster rate.
Dengue Hemorrhagic Fever
The Dengue Hemorrhagic Fever is a rare development that is defined by distinctive symptoms. Those symptoms include high fever, damage to the blood and lymph vessels, bleeding from the nose and gums, enlargement of the liver, and failure of the circulatory system. This happens after repeatedly being exposed to the Dengue virus. Getting Dengue Hemorrhagic Fever is at a higher risk for infants and small children, pregnant women because the virus could be passed to the fetus, older adults, and those who has weakened immune systems. Doctors will usually diagnose you with the virus infection and then start to look for the symptoms of Dengue Hemorrhagic Fever. The drawbacks of Dengue Hemorrhagic Fever are seizures, brain damage, blood clots, damage to the lungs and liver, heart damage, shock, and death.
People with the Dengue Fever that get care in the early stages of infection will most likely recover. Researchers are working on a vaccine to help prevent the Dengue Hemorrhagic Fever but it’s currently unavailable. The best way to help prevent getting infected is to avoid getting bitten by a mosquito. Especially when traveling to the tropics. To avoid getting bitten by a mosquito, wear clothing that covers the legs and arms as well as using mosquito netting and repellant.
The Infectious and Replication Cycle of the Dengue Virus
The infectious cycle starts when the virus gets attached to a human skin cell. Then the skins cell’s membrane folds around the virus and forms a pouch, called an endosome, that seals around the virus particles. The Dengue virus takes over the normal use of an endosome, which is to take in, from the outside, large molecules and particles for nourishment, so that the virus can enter the host cell. Then the Dengue virus keeps going deeper still inside the endosome until two conditions are met. Those two conditions are the environment must be acidic and the membrane of the endosome has to have a negative charge. These conditions allow the viral envelope to blend with the endosomal membrane and releases the virus into the cell.
After being released, the viral RNA takes over the host’s organelles to start the replication cycle. It uses the ribosomes on the rough endoplasmic reticulum to translate itself and assemble the viral polypeptide. The polypeptide is cut to form 10 proteins. Three of those proteins are structural and the other seven are nonstructural. The three structural proteins are called Capsid, Envelope, and Membrane. The seven nonstructural proteins are NS1, NS2A & B, NS3, NS4A & B, and NS5. The nonstructural proteins play a role in the replication and assembly of the Dengue virus.
After the polypeptide is cut, the new RNA is encased in Capsid proteins, making it a nucleocapsid. The new nucleocapsid is then enters the rough endoplasmic reticulum to be surrounded by the membrane of the endoplasmic reticulum and Envelope and Membrane proteins to add a viral envelope as well as a protective outer layer. These immature viruses travel through the Golgi apparatus complex to mature and switch to their infectious form. They are then released from the cell to infect another cell.
To conclude this research paper on the Dengue Fever and the viruses that cause it, I have learned a lot. I had never heard of this type of virus before and it was interesting learning about how it affected humans. I didn’t know anything about the Dengue Fever and I think that I understand what it is at the end of my research. It’s a lot more common than I had originally thought and it has some very serious symptoms if not treated early on. This virus will make me think twice before traveling in any tropical areas.