by Dr. Behrouz Hashim
Mosquitoes carry life-threatening diseases such as dengue, malaria yellow fever and encephalitis. The World Health Organization estimates that each year 300-500 million cases of malaria occur and more than one million people die of it. Some 2,500 million people (2/5of the world’s population) are now at risk from dengue. World Health Organization (WHO) estimates there may be 50 million cases of dengue infection worldwide every year.
Dengue fever is a flu-like illness spread by the bite of an infected mosquito. Dengue hemorrhagic fever is a severe, often fatal, complication of dengue fever.
WHAT IS THE INFECTIOUS AGENT THAT CAUSES DENGUE?
Dengue and dengue hemorrhagic fever are caused by any of the four types of viruses. Infection with one virus does not protect a person against infection with another.
HOW IS DENGUE SPREAD?
Dengue is spread by the bite of an Aedes mosquito. The mosquito transmits the disease by biting an infected person and then biting someone else.
WHERE IS DENGEI FOUND?
Dengue viruses occur in most tropical areas of the world. It is common in Africa, Asia, the pacific, Australia and America. It is widespread in the Caribbean basin. Dengue is most common in cities but can be found in rural areas. It is rarely found in mountainous areas above 4,000 feet.
The mosquitoes that transmit dengue live among humans and breed in discarded tires, flower pots, old oil drums, and water storage containers close to human dwellings. Unlike the mosquitoes that cause malaria which prefers to bite at night, the dengue mosquitoes prefer to bite mainly during the day.
WHAT ARE THE SIGNS AND SYPTOMS OF DENGUE FEVER AND DENGUE HEMORRHAGIC FEVER?
Dengue fever usually starts suddenly with high fever, rash, severe headache, pain behind the eyes, and muscle and joint pain. The severity of the joint pain has given dengue the name Break Born Fever, Nausea, vomiting, and loss of appetite and common. A rash usually appears three to four days after the initiation of fever. The illness can last up to 10 days, but complete recovery can take as long as a month.
Older, children and adults are usually sicker than young children.
Most dengue infections result in relatively mild illness, but some can progress to dengue hemorrhagic fever. With dengue hemorrhagic fever, the blood vessels start to leak and cause bleeding from the nose, mouth, and gums. Bruising can be a sign of bleeding inside the body. Without prompt treatment, the blood vessels can collapse, causing shock (dengue shock syndrome). Dengue hemorrhagic fever is fatal in about two to five percent of cases, mostly among children and young adults.
HOW SOON AFTER EXPOSURE DO SYMPTOMS APPEAR?
The time between the bite of a mosquito carrying dengue virus and the beginning of symptoms averages four to six days with a range of three to 14 days. An infected person cannot spread the infection to another person but can be a source of dengue virus for mosquitoes for about 6 days.
HOW IS DENGUE DIAGNOSED?
Dengue is diagnosed by a blood test.
WHAT IS THE TREATMENT FOR DENGUE AND DENGUE HEMORRHAGIC FEVER?
There is no specific treatment for dengue. Persons with dengue fever should rest and drink plenty of fluids. They should be kept away from mosquitoes for the protection of others. Dengue hemorrhagic fever is treated by replacing lost fluids. Some patients need transfusions to control bleeding.
HOW COMMON IS DENGUE?
In tropical countries around the world, dengue is one of the most common viral diseases spread to humans by mosquitoes, Tens of millions of cases of dengue fever and up to hundreds of thousands of cases of dengue hemorrhagic fever occur each year.
WHY IS DENGUE INCREASING IN THE WORLD?
All types of dengue virus are re-emerging worldwide and causing larger and more frequent epidemics, especially in cities in the tropics. The emergency of dengue as a major public health problem has been most dramatic in the western hemisphere. Several factors are contributing to the resurgence of dengue fever:
● No effective mosquito control efforts are underway in most countries with dengue.
● Rapid growth of cities in tropical countries has led to overcrowding, urban decay, and substandard sanitation, allowing more mosquitoes to live closer to more people.
● The increase in non-biodegradable plastic packaging and discarded tires is creating new breeding sites for mosquitoes.
● Increased jet air travel is helping people infected with dengue viruses to move easily from city to city.
HOW CAN DENGUE BE PREVENTED?
There is no vaccine to prevent dengue. Eliminating mosquito breeding sites in these areas is another key prevention measure.
Avoid mosquito bites when travelling in tropical areas.
● Use mosquito repellents on skin and clothing.
● When outdoors, wear long-sleeved shirts and long pants tucked into socks.
● Avoid heavily populated residential areas.
● When indoors, stay in air-conditioned or screened areas. Use bed nets if sleeping areas are not screened or air-conditioned.
● If you have symptoms of dengue, report your travel history to your doctor.
● Eliminate mosquito breeding sites around homes. Discard items that can collect rain or run-off water, especially old tires.
● Regularly change the water in outdoor bird baths and pet and animal water containers.
Malaria is caused by plasmodium parasites are spread to people through the bites of infected Anopheles mosquitoes, called malaria vectors, which bite mainly between dusk and dawn.
There are four types of human malaria:
Plasmodium falciparum and Plasmodium vivax are the most common. Plasmodium falciparum is the most deadly.
Malaria is transmitted exclusively through the bites of Anopheles mosquitoes. Transmission also depends on climactic conditions that may affect the abundance and survival of mosquitoes, such as rainfall patterns temperature and humidity. In many places, transmission is seasonal, with the peak during and just after the rainy season.
Malaria can also be transmitted from a mother to her unborn baby (congenitally) and by blood transfusions.
● Anemia ● Bloody stools ● Chills ● Coma ● Convulsion ● Fever ● Headache
● Jaundice ● Muscle pain ● Nausea ● Sweating ● Vomiting
Malaria is an acute febrile illness. Symptoms appear seven days or more (usually 10-15 days) after the infective mosquito bite. The first symptoms – fever, headache, chills and vomiting – may be mild and difficult to recognize as malaria. If not treated within 24 hours, P. falciparum malaria can progress to severe illness often leading to death. For both P. vivax and P. ovale, clinical relapses may occur weeks to months after the first infection.
DIAGNOSIS AND TREATMENT
Early diagnosis and treatment of malaria reduces disease and prevents deaths. It also contributes to reducing malaria transmission.
The best available treatment particularly for P. falciparum malaria is artemisinin-based combination therapy (ACT).
Malaria is a parasitic disease that involves high fevers, shaking chills, flu-like symptoms, and anemia.
CAUSES, INCIDENCE, AND RISK FACTORS
Malaria is caused by a parasite that is passed from one human to another by the bite of infected Anopheles mosquitoes. After infection, the parasites (called sporozoites) travel through the bloodstream to the liver, where they mature and release another form, the merozoites. The parasites enter the bloodstream and infect red blood cells.
They multiply inside the red blood cells, which then break open within 48 to 72
hours, infecting more red blood cells. The first symptoms usually occur 10 days to four weeks after infection, through they can appear as early as eight days or as long as a year after infection. The symptoms occur in cycles of 48 to 72 hours.
Recently, a fifth type, Plasmodium Knowlesi, has been causing malaria in Malaysia and areas of Southeast Asia. Another type, falciparum malaria, affects more red blood cells than the other types and is much more serious. It can be fatal within a few hours of the first symptoms.
●Anemia ● Bloody stools ●Chills ●Coma ●Convulsion ●Fever ●Headache ●Jaundice ●Muscle pain ●Nausea ●Sweating ●Vomiting
SIGNS AND TESTS
During the physical examination, the doctor may find an enlarged liver or enlarged spleen. Malaria blood smears taken at 6 to 12 hour intervals confirm the diagnosis.
A complete blood count (CBC) will identify anemia if it is present.
Serum ICT blood test.
Malaria especially Falciparum malaria, is a medical emergency that requires a hospital stay. Chloroquine is often used as an anti-malarial medication. However, chloroquine-resistant infections are common in some parts of the world.
The best available treatment, particularly for P. falciparum malaria, is artemisinin-based combination therapy (ACT).
● Brain infection (cerebritis)
● Destruction of blood cells (hemolytic anemia)
● Kidney failure
● Liver failure
● Respiratory failure from fluid in the lungs (pulmonary edema)
Rupture of the spleen leading to massive internal bleeding (hemorrhage)
Following drugs: mefloquine, doxycycline, chloroquine, hydroxychloroquine, or Malarone. Even pregnant women should take preventive medications because the risk to the fetus from the medication is less than the risk of catching this infection.
You can prevent malaria and dengue by:
● Keeping mosquitoes from biting you, especially at night for malaria and during the day from dengue.
● Taking antimalarial drugs to kill the parasites.
● Eliminating places around your home where mosquitoes breed.
● Sleeping under mosquito nets – especially effective if they have been treated with insecticide and wearing or using insect repellent and long-sleeved clothing if out-doors.