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Monday, October 11, 2010

Beware of Mosquito-Borne Diseases Malaria, Chikungunya and Dengue Fever

The monsoon rains are definitely welcomed by one and all for several reasons, but they also cause the spread of various water-borne and mosquitogenic diseases that can be fatal to many. Beware of the buzz of the mosquitoes. The most common mosquito-borne diseases are Malaria, Dengue and Chikungunya, which have become a growing concern over the past decade as many people have been severely affected. Last month, there was a rise in dengue, chikungunya and malaria cases reported in India. 

Since all the three of the diseases mentioned above are caused by mosquitoes and characterised by fever, it is very important to be aware of the signs and symptoms of each so you can diagnose the condition as early as possible and begin the treatment. So how do you differentiate between Malaria, Dengue Fever and Chikungunya?


Malaria is a worldwide disease that has been around for more than 50,000 years. The disease is widespread in the tropical and sub-tropical regions, including the Americas, Asia and Africa. Each year about 350–500 million cases are reported. About 1 million of those succumb to the disease. According to WHO, there are 109 countries in Africa, Asia and Latin America, which are affected by Malaria. WHO observed April 15, 2010, as World Malaria Day 2010, and has declared Dec. 31, 2010, as the universal coverage deadline for delivering effective and affordable protection and treatment to all people at risk of malaria.

Malaria is an infectious and life-threatening disease that is caused by Plasmodium parasites, which are transmitted to people through the bites of infected Anopheles mosquitoes. These mosquitoes are called “vectors.” There are four species of malaria, of which Plasmodium falciparum is the most serious. The other three, P. vivax, P. malariae, and P. ovale, are generally less serious and not considered to be life threatening.

The characteristic signs and symptoms of malaria appear seven days (usually 10-15 days) after the infective mosquito bite. The person has fever with chills, headache and vomiting, which may be mild and difficult to diagnose initially. A typical sign of malaria is a cycle of chills, fever, and sweating that repeats every one, two or three days. There can also be vomiting, diarrhea, coughing, and yellowing of the skin and whites of the eyes due to the destruction of red blood cells and liver cells. A simple blood test can detect the malarial parasites within the red blood cells of an infected person and confirm the diagnosis.

**Useful Resources for Malaria:

National Institute of Malaria Research
Guidelines for Diagnosis and Treatment of Malaria in India
All about Malaria


Chikungunya and Dengue are both viral diseases caused by the bite of Aedes Egyptii Mosquitoes, which breed only in fresh water that has stagnated in flowerpots, cans, air conditioners, etc. In Asia, the mosquitoes Aedes aegypti and Aedes albopictus are the two main species involved in transmitting the virus from infected individuals to healthy contacts. They usually bite during the daylight hours. Chikungunya was first detected in the year 1952 at a place called Makonde Plateau, in Africa. Since then, Chikungunya virus (CHIK) outbreaks, which are known to occur cyclically, have occurred occasionally in Africa, South Asia and Southeast Asia, and most recently in limited areas of Europe. The name ‘Chikungunya’ is derived from a root verb in the Kimakonde language that means "to become contorted" and describes the stooped appearance of sufferers with joint pain. The good news is that this virus is not contagious and therefore the disease does not spread from person to person, but only from the bite of the infected female mosquitoes. More than 1.25 million suspected cases were reported in India in 2006.

CHIK viral infection begins with a short incubation period of 2-4 days. Typically, after 48 hours of being bitten by an infected mosquito, the person will experience sudden high fever with shaking chills. Sometimes they may also develop a maculopapular rash (red flat patches that may contain small raised spots) over the trunk, limbs and face, which may last for 3 or 4 days. However, the most common symptom is severe muscle pain and joint pain. Pain initially starts in the small joints of the hands and feet, wrists and ankles, and later the larger joints. Most patients recover fully, but in some cases joint pain may persist for several months, or even years. Other non-specific symptoms may include headache, slight photophobia and insomnia.

**Useful Resources for Chikungunya:

How to Recognize Chikungunya Fever Symptoms
Treatment and Prevention of Chikungunya Fever
WHO / Chikungunya – Complete Information
Chikungunya - Frequently Asked Questions
Molecular and serological diagnosis of Chikungunya virus infection

Dengue Fever

Dengue, also known as Dengue Fever, is a viral disease that imitates influenza and is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas. The WHO site says, “Some 2.5 billion people--two fifths of the world's population – are now at risk from dengue. WHO currently estimates there may be 50 million dengue infections worldwide every year. In 2007 alone, there were more than 890,000 reported cases of dengue in the Americas, of which 26,000 cases were DHF.” It was during the dengue epidemics in the Philippines and Thailand in the 1950s that Dengue haemorrhagic fever (DHF) was first recognized to have potentially lethal complications. Today, DHF affects most Asian countries and has become a leading cause of hospitalisation and death among children in the region.

Dengue is caused by four distinct serotypes of viruses and affects people with low levels of immunity. Therefore, it is possible for a person 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 is also known as “breakbone fever” or “dandy fever” due to the intense joint pains and muscle pains suffered by the patient.

The characteristic sign of dengue fever is a severe, flu-like illness that affects infants, young children and adults, but seldom causes death. The infants and young children may develop rashes along with the fever, whereas older children and adults may have either a mild fever or the classical incapacitating disease with abrupt onset and high fever, severe headache, pain behind the eyes, muscle and joint pains, and rash. Classically, the symptoms of dengue fever may range from a mild fever to incapacitating high fever, with severe headache, pain behind the eyes, muscle and joint pain, and rash.

**Useful Resources for Dengue Fever:

What is dengue and how is it treated?
Dengue/dengue haemorrhagic fever
Information on Dengue Fever: Signs Symptoms, Diagnosis, Treatment and Prevention
CDC - Dengue

It goes without saying that the best method to prevent these diseases is to control the breeding of mosquitoes in stagnating water and to use mosquito repellents. Travellers need to take precautions when going to tropical countries, since some locations, as well as some seasons, can be of a higher risk. It is best to keep in mind that the mosquitoes that bite during “daytime” transmit dengue fever and yellow fever, whereas the mosquitoes that bite during the “night time” transmit malaria and Japanese encephalitis.

The following precautions can be taken:
  1. Taking prescription anti-malarial drugs.
  2. Practise the 5 “D”s – Don’t go out during Dusk and Dawn. Dress so your skin is protected from mosquito bites (long shirt sleeves and pants). Apply mosquito repellent containing Deet to bare skin and clothing. Drain out water to avoid stagnation and dry out the containers.
  3. Use mosquito netting to sleep. It is proved to be the most effective way of preventing mosquito bites.
  4. Sleep in an air-conditioned room or well-screened room.
Note: Chloroquine is NOT an effective anti-malarial drug in India and should not be taken to prevent malaria in this region.

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