Dengue fever is caused by Dengue virus (DENV), a mosquito-borne flavivirus. DENV is an ssRNA positive-strand virus of the family Flaviviridae; genus Flavivirus. There are four serotypes of DENV. The virus has a genome of about 11000 bases that codes for three structural proteins, C, prM, E; seven nonstructural proteins, NS1, NS2a, NS2b, NS3, NS4a, NS4b, NS5; and short non-coding regions on both the 5' and 3' ends.
Tuesday, October 27, 2009
How Dengue fever can be prevented?
The transmission of the virus to mosquitoes must be interrupted to prevent the illness. To this end, patients are kept under mosquito netting until the second bout of fever is over and they are no longer contagious.
The prevention of dengue requires control or eradication of the mosquitoes carrying the virus that causes dengue. In nations plagued by dengue fever, people are urged to empty stagnant water from old tires, trash cans, and flower pots. Governmental initiatives to decrease mosquitoes also help to keep the disease in check but have been poorly effective.
Wear long pants and long sleeves. For personal protection, use mosquito repellant sprays that contain DEET when visiting places where dengue is endemic. Limiting exposure to mosquitoes by avoiding standing water and staying indoors two hours after sunrise and before sunset will help. The Aedes aegypti mosquito is a daytime biter with peak periods of biting around sunrise and sunset. It may bite at any time of the day and is often hidden inside homes or other dwellings, especially in urban areas.
There is currently no vaccine available for dengue fever. There is a vaccine undergoing clinical trials, but it is too early to tell if it will be safe or effective.
References: http://www.phac-aspc.gc.ca/tmp-pmv/2007/dengue070823_e.html
http://www.cdc.gov/ncidod/dvbid/dengue/
The prevention of dengue requires control or eradication of the mosquitoes carrying the virus that causes dengue. In nations plagued by dengue fever, people are urged to empty stagnant water from old tires, trash cans, and flower pots. Governmental initiatives to decrease mosquitoes also help to keep the disease in check but have been poorly effective.
Wear long pants and long sleeves. For personal protection, use mosquito repellant sprays that contain DEET when visiting places where dengue is endemic. Limiting exposure to mosquitoes by avoiding standing water and staying indoors two hours after sunrise and before sunset will help. The Aedes aegypti mosquito is a daytime biter with peak periods of biting around sunrise and sunset. It may bite at any time of the day and is often hidden inside homes or other dwellings, especially in urban areas.
There is currently no vaccine available for dengue fever. There is a vaccine undergoing clinical trials, but it is too early to tell if it will be safe or effective.
References: http://www.phac-aspc.gc.ca/tmp-pmv/2007/dengue070823_e.html
http://www.cdc.gov/ncidod/dvbid/dengue/
Dengue Hemorrhagic Fever
Dengue hemorrhagic fever (DHF) is a specific syndrome that tends to affect children under 10. It causes abdominal pain, hemorrhage (bleeding), and circulatory collapse (shock). DHF is also called Philippine, Thai, or Southeast Asian hemorrhagic fever and dengue shock syndrome.
DHF starts abruptly with high continuous fever and headache. There are respiratory and intestinal symptoms with sore throat, cough, nausea, vomiting, and abdominal pain. Shock occurs two to six days after the start of symptoms with sudden collapse, cool, clammy extremities (the trunk is often warm), weak pulse, and blueness around the mouth (circumoral cyanosis).
In DHF, there is bleeding with easy bruising, blood spots in the skin (petechiae), spitting up blood (hematemesis), blood in the stool (melena), bleeding gums, and nosebleeds (epistaxis). Pneumonia is common, and inflammation of the heart (myocarditis) may be present.
Patients with DHF must be monitored closely for the first few days since shock may occur or recur precipitously. Cyanotic (bluish) patients are given oxygen. Vascular collapse (shock) requires immediate fluid replacement. Blood transfusions may be needed to control bleeding.
The mortality, or death rate, with DHF is significant. It ranges from 6%-30%. Most deaths occur in children. Infants under a year of age are especially at risk of dying from DHF.
DHF starts abruptly with high continuous fever and headache. There are respiratory and intestinal symptoms with sore throat, cough, nausea, vomiting, and abdominal pain. Shock occurs two to six days after the start of symptoms with sudden collapse, cool, clammy extremities (the trunk is often warm), weak pulse, and blueness around the mouth (circumoral cyanosis).
In DHF, there is bleeding with easy bruising, blood spots in the skin (petechiae), spitting up blood (hematemesis), blood in the stool (melena), bleeding gums, and nosebleeds (epistaxis). Pneumonia is common, and inflammation of the heart (myocarditis) may be present.
Patients with DHF must be monitored closely for the first few days since shock may occur or recur precipitously. Cyanotic (bluish) patients are given oxygen. Vascular collapse (shock) requires immediate fluid replacement. Blood transfusions may be needed to control bleeding.
The mortality, or death rate, with DHF is significant. It ranges from 6%-30%. Most deaths occur in children. Infants under a year of age are especially at risk of dying from DHF.
Treatemant of Dengue
There is no specific medicine or antibiotic to treat it. For typical dengue, the treatment is purely concerned with relief of the symptoms (symptomatic).
Rest and fluid intake for adequate hydration is important.
Use of acetylsalicylic acid (e.g. aspirin) and non steroidal anti-inflammatory drugs (e.g. Ibuprofen) is not recommended.
Acetaminophen (Tylenol) and codeine may be given for severe headache and for the joint and muscle pain (myalgia).
Rest and fluid intake for adequate hydration is important.
Use of acetylsalicylic acid (e.g. aspirin) and non steroidal anti-inflammatory drugs (e.g. Ibuprofen) is not recommended.
Acetaminophen (Tylenol) and codeine may be given for severe headache and for the joint and muscle pain (myalgia).
signs and symptoms of Dengue
Dengue starts with chills, headache, pain upon moving the eyes, and low backache.
Painful aching in the legs and joints occurs during the first hours of illness.
The temperature rises quickly as high as 104° F (40° C), with relative low heart rate (bradycardia) and low blood pressure (hypotension).
The eyes become reddened. A flushing or pale pink rash comes over the face and then disappears.
The glands (lymph nodes) in the neck and groin are often swollen.
Fever and other signs of dengue last for two to four days, followed by rapid drop in temperature (defervescence) with profuse sweating.
This precedes a period with normal temperature and a sense of well-being that lasts about a day. A second rapid rise in temperature follows.
A characteristic rash appears along with the fever and spreads from the extremities to cover the entire body except the face. The palms and soles may be bright red and swollen.
How is dengue contracted?
The virus is contracted from the bite of a striped Aedes aegypti mosquito that has previously bitten an infected person. The mosquito flourishes during rainy seasons but can breed in water-filled flower pots, plastic bags, and cans year-round. One mosquito bite can inflict the disease.
The virus is not contagious and cannot be spread directly from person to person. There must be a person-to-mosquito-to-another-person pathway.
The virus is not contagious and cannot be spread directly from person to person. There must be a person-to-mosquito-to-another-person pathway.
WHAT IS DENGUE FEVER
Dengue fever is a disease transmitted by the bite of an Aedes mosquito infected with any one of the four dengue viruses. It occurs in tropical and sub-tropical areas of the world. Symptoms appear 3—14 days after the infective bite. Dengue fever is a febrile illness that affects infants, young children and adults.
It is an acute illness of sudden onset that usually follows a benign course with headache, fever, exhaustion, severe joint and muscle pain, swollen glands (lymphadenopathy), and rash. The presence (the "dengue triad") of fever, rash, and headache (and other pains) is particularly characteristic of dengue.
Dengue (pronounced DENG-gay) strikes people with low levels of immunity. Because it is caused by one of four serotypes of virus, it is possible to get dengue fever multiple times. However, an attack of dengue produces immunity for a lifetime to that particular serotype to which the patient was exposed.
Dengue goes by other names, including "breakbone" or "dandy fever." Victims of dengue often have contortions due to the intense joint and muscle pain, hence the name breakbone fever. Slaves in the West Indies who contracted dengue were said to have dandy fever because of their postures and gait.
Dengue hemorrhagic fever is a more severe form of the viral illness. Manifestations include headache, fever, rash, and evidence of hemorrhage in the body. Petechiae (small red or purple blisters under the skin), bleeding in the nose or gums, black stools, or easy bruising are all possible signs of hemorrhage. This form of dengue fever can be life-threatening or even fatal.
It is an acute illness of sudden onset that usually follows a benign course with headache, fever, exhaustion, severe joint and muscle pain, swollen glands (lymphadenopathy), and rash. The presence (the "dengue triad") of fever, rash, and headache (and other pains) is particularly characteristic of dengue.
Dengue (pronounced DENG-gay) strikes people with low levels of immunity. Because it is caused by one of four serotypes of virus, it is possible to get dengue fever multiple times. However, an attack of dengue produces immunity for a lifetime to that particular serotype to which the patient was exposed.
Dengue goes by other names, including "breakbone" or "dandy fever." Victims of dengue often have contortions due to the intense joint and muscle pain, hence the name breakbone fever. Slaves in the West Indies who contracted dengue were said to have dandy fever because of their postures and gait.
Dengue hemorrhagic fever is a more severe form of the viral illness. Manifestations include headache, fever, rash, and evidence of hemorrhage in the body. Petechiae (small red or purple blisters under the skin), bleeding in the nose or gums, black stools, or easy bruising are all possible signs of hemorrhage. This form of dengue fever can be life-threatening or even fatal.
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