THE UNITED REPUBLIC OF TANZANIA
MINISTRY OF HEALTH AND SOCIAL WELFARE
Telegrams “AFYA”
Tel: 255-51-20261 General
(All letters should be addressed to
The Permanent Secretary)
P.O. Box 9083,
Dar es Salaam.
Tanzania
Dengue Fever
Disease Fact Sheet
What is Dengue fever (DF)?
Dengue fever is transmitted by the bite of an Aedes mosquito infected with a dengue virus. The mosquito becomes infected when it bites a person with dengue virus in their blood. It can’t be spread directly from one person to another person..
Symptoms, which usually begin four to six days after infection and last for up to 10 days, may include
o Sudden, high fever
o Severe headaches
o Pain behind the eyes
o Severe joint and muscle pain
o Nausea
o Vomiting
o Skin rash, which appears three to four days after the onset of fever
o Mild bleeding (such a nose bleed, bleeding gums, or easy bruising)
Sometimes symptoms are mild and can be mistaken for those of the flu or another viral infection. Younger children and people who have never had the infection before tend to have milder cases than older children and adults. However, serious problems can develop. These include dengue hemorrhagic fever, a rare complication characterized by high fever, damage to lymph and blood vessels, bleeding from the nose and gums, enlargement of the liver, and failure of the circulatory system. The symptoms may progress to massive bleeding, shock, and death. This is called dengue shock syndrome (DSS).
People with weakened immune systems as well as those with a second or subsequent dengue infection are believed to be at greater risk for developing dengue hemorrhagic fever.
Can people suffer from dengue and not appear ill?
Yes. There are many people who are infected with the virus and do not suffer from any signs or symptoms of the disease. For every patient with symptoms and signs there may be 4-5 persons with no symptoms or with very mild symptoms.
How can someone get dengue fever?
Dengue fever occurs following the bite of an infected mosquito Aedes aegypti.This type of mosquito has a peculiar white spotted body and legs and is easy to recognize even by laymen. It breeds in clean water) and has a flight range of only 100 – 200 metres. The mosquito gets the Dengue virus after biting a human being infected with dengue virus. This type of mosquito likes to bite in the afternoon unlike the anopheles mosquito which bites in the night.
Where does the mosquito that spreads dengue live?
The highly domestic mosquito Aedes aegypti rests indoors, in closets and other dark places. Outside it rests where it is cool and shaded. The female mosquito lays her eggs in water containers in and around the homes, and other dwellings. These eggs will develop, become larvae, and further develop into adults in about 10 days.
Can I get dengue fever from another person?
Dengue does not spread directly from person to person. It is only spread through the bite of an infected mosquito.
Can the diagnosis of dengue be confirmed?
Yes. The National Health Laboratory and Quality Assurance Training Centre (NHLQATC) can do the confirmation either by isolating the virus using PCR or detecting antibodies using ELISA.
Can you get dengue again after suffering from it once?
It is possible to get dengue more than once. Dengue virus has 4 different strains, so if a person has suffered from one virus, there can be a repeat occurrence of dengue if a different strain is involved subsequently. Being affected by one strain offers no protection against the others. A person could suffer from dengue more than once in her/his lifetime.
What is the treatment? Is it curable?
Like most viral diseases there is no specific cure for dengue fever. Antibiotics do not help. Paracetamol is the drug of choice to bring down fever and joint pain. Other medicines such as Aspirin and Brufens hould be avoided since they can increase the risk of bleeding. Any medicines that decrease platelets should be avoided.
Is there a vaccine to prevent dengue fever?
No Vaccine is available.
Can dengue fever become dangerous?
The infection can become dangerous since it may cause damage to the blood vessels. The damage may range from increased permeability of the blood vessels, causing leakage of blood fluid/plasma into various organs to completely broken blood vessels that causes bleeding.The symptoms and signs of dengue haemorrhagic fever and dengue shock syndrome are related to damage to the blood vessels and derangement in functioning in components of blood that help it to clot.
People who suffer from dengue fever have no risk of death but some of them develop Dengue Haemorrhagic Fever or Dengue Shock Syndrome. In some of these cases death can occur. With proper treatment, the patients with Dengue haemorrhagic fever and dengue shock syndrome can recover fully. Good treatment provided in time can save most lives.
When should a patient suffering from Dengue go to the hospital or consult a doctor?
Generally the progress towards dengue haemorrhagic fever or dengue shock syndrome occur after 3-5 days of fever. At this time, fever has often come down. This may mislead many of us to believe that the patient is heading towards recovery. In fact, this is the most dangerous period that requires high vigilance from care-givers. The signs and symptoms that should be looked for are severe pain in the abdomen, persistent vomiting, bleeding from any site like, bleeding in the skin appearing as small red or purplish spots, nose bleed, bleeding from gums, passage of black stools like coal tar. Bring the patient to the hospital whenever the first two signs, namely, severe pain in the abdomen and persistent vomiting are detected.
The most dangerous type of dengue is the dengue shock syndrome. It is recognized by signs like excessive thirst, pale and cold skin (due to very low blood pressure), restlessness and a feeling of weakness.
Are there any long term ill effects of dengue fever?
Most people who suffer from dengue fever recover in 1-2 weeks time. Some may feel tired for several weeks. However, if symptoms persist after this period, consult a doctor.
What should the doctors treating dengue do ?
Patients suspected to be suffering from dengue haemorrhagic fever or dengue shock syndrome should be admitted to a hospital without delay. The progress of these patients should be monitored regularly at 1-2 hours interval. Platelet counts and haematocrits should be monitored repeatedly to review the progress of patients. If the haematocrit levels fall dangerously then a blood transfusion should be considered. A fall of more than 20 % as compared to previous levels may be an indication for transfusion.
If the haematocrit values rise the patient should be given fluids intravenously and the fluids carefully monitored to ensure that the patient does not get excess fluids. A rise of more than 20 % as compared to previous levels may be an indication for IV fluids. The doctor should decide based on best judgement of patient's condition.
Preventive measures
Vector control: Dengue mosquitoes breed in stored, exposed water collections. Favoured places for breeding are barrels, drums, jars, pots, buckets, flower vases, plant saucers, tanks, discarded bottles, tins, tyres, water coolers etc. To prevent the mosquitoes from multiplying, drain out the water from desert coolers/window air coolers (when not in use), tanks, barrels, drums, buckets etc. Remove all objects containing water (e.g. plant saucers etc.) from the house. Collect and destroy discarded containers in which water collects e.g. bottles, plastic bags, tins, used tyres etc.
Protecting against Aedes mosquito bite: There is no way to tell if a mosquito is carrying the dengue virus. Therefore, people must protect themselves from all mosquito bites. Dengue mosquitoes bite during the day time throughout the day. Highest biting intensity is about 2 hours after sunrise and before sunset. Wear full sleeves clothes and long dresses to cover as much of your body as possible. Use repellents and be careful in using them in young children and old people. Use mosquito coils and electric vapour mats during the daytime also to prevent dengue. Use treated mosquito nets to protect children, old people and others who may rest during the day.
Prepared by:
Epidemiology and Disease control section
Ministry of Health and Social Welfare
NB: Information was borrowed from CDC and WHO Websites
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