Patient Education
What is malaria?
Malaria is a potentially life-threatening disease caused by parasites that are transmitted to people through the bites of infected mosquitoes. It is very common in tropical countries. Malaria is caused by Plasmodium parasites. The 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 Plasmodium species that cause malaria in humans:
- Plasmodium falciparum
- Plasmodium vivax
- Plasmodium malaria
- Plasmodium ovale.
Malaria is preventable and curable, and increased malaria prevention and control measures are dramatically reducing the malaria burden globally.
Plasmodium falciparum and Plasmodium vivax are the most common parasites seen in India. Plasmodium falciparum is the most deadly.
How does malaria spread?
Malaria is transmitted exclusively through the bites of Anopheles mosquitoes. A female anopheles mosquito carries the malarial parasites in its saliva and whenever it bites a human, it transmits the malaria parasites leading to infection. These malaria parasites then circulate to the liver, multiply and infect the red cells in the blood. Every time the red cells are destroyed, more parasites are released in the circulation causing fever with shivering and chills.
All of the important vector species bite at night. Anopheles mosquitoes breed in water and each species has its own breeding preference; for example, some prefer shallow collections of freshwater, such as puddles, rice fields, and hoof prints. In many places, the transmission is seasonal, with a peak during and just after the rainy season. Malaria epidemics can occur when climate and other conditions suddenly favor transmission in areas where people have little or no immunity to malaria. They can also occur when people with low immunity move into areas with intense malaria transmission, for instance, to find work, or as refugees. In areas where malaria transmits regularly, partial immunity is developed in adults over years of exposure, and while it never provides complete protection, it does reduce the risk that malaria infection will cause severe disease. For this reason, most malaria deaths occur in young children.
Who is at risk of contracting malaria?
Specific risk groups include:
- young children who have not yet developed protective immunity against the most severe forms of the disease
- non-immune pregnant women as malaria cause high rates of miscarriage and can lead to maternal death
- people with HIV/AIDS
- international travellers from non-endemic areas because they lack immunity
What are the symptoms of malaria?
Malaria is an acute febrile illness. Symptoms usually appear 10-15 days after the infective mosquito bites. 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. In young children, rigors and chills may not be seen. Children with severe malaria frequently develop one or more of the following symptoms: severe anemia (fall in hemoglobin), breathing difficulty, jaundice, kidney failure, or brain involvement(cerebral malaria). In malaria-endemic areas, persons may develop partial immunity, allowing asymptomatic infections to occur. Untreated falciparum malaria can lead to death and hence needs to be treated aggressively and urgently.
For both P. vivax and P. ovale, recurring infections or relapses may occur weeks to months after the first infection. These new episodes arise from dormant liver forms of the parasite. Special treatment, targeted at these liver stages, is required for a complete cure.
How is the diagnosis of malaria made?
Diagnosis of malaria can be made by certain blood tests and demonstrations of the malaria parasite in the blood smear. Rapid bedside diagnostic tests are now available that can detect both vivax and falciparum malaria and can give results in less than 15 minutes.
It is recommended that all cases of suspected malaria be confirmed using parasite-based diagnostic testing before administering treatment.
How is malaria treated?
Malaria can be a severe, potentially fatal disease (especially when caused by Plasmodium falciparum) and treatment should be initiated as soon as possible.
Patients who have severe P. falciparum malaria or who cannot take oral medications should be given the treatment by intravenous infusion.
Most drugs used in the treatment are active against the parasite forms in the blood (the form that causes disease) and include chloroquine, artemether-lumefantrine (Lumerax), quinine, doxycycline and clindamycin, and artesunate.
In addition, primaquine is active against the dormant parasite liver forms and prevents relapses. Primaquine should not be taken by pregnant women or by people who are deficient in G6PD (glucose-6-phosphate dehydrogenase). Patients should not take primaquine until a screening test has excluded G6PD deficiency.
How can malaria be prevented?
Controlling mosquito populations is the main way to reduce malaria transmission at the community level.
For individuals, personal protection against mosquito bites represents the first line of defense for malaria prevention.
The two forms of mosquito control used as part of public health measures are insecticide-treated mosquito nets and indoor spraying with residual insecticides.
For personal protection, these measures ought to be followed:
- Wear a long-sleeved shirt, long pants, and socks.
- Apply lotion, liquid, or spray repellent to exposed skin.
- Ensure adequate protection during times of day when mosquitoes are most active. Malaria vector mosquitoes bite mainly from dusk to dawn.
- Reapply repellents as protection wanes and mosquitoes start to bite.
- Avoid pooling of water that can be breeding ground for mosquitoes.
- In monsoon season, use mosquito nets and mosquito coils.
- Application of mosquito repellants such as DEET can help to prevent mosquito bites when outdoors.
If a traveler wishes to visit an area that has a high incidence of malaria, what precautions should he take?
If a traveler is coming to an area with high endemicity of malaria, then he should start chloroquine (once a week) at least one week prior to coming to that country and continue taking it for at least 4 weeks after he leaves the area. In addition, he should take general precautions to prevent mosquito bites.
Is there any vaccine to prevent malaria?
Very recently in July 2015, the first-ever malaria vaccine Mosquirix has been approved by European regulators, although it's still a far way to go before it will be available for use in India.
GlaxoSmithKline worked with the PATH Malaria Vaccine Initiative to develop the vaccine against the Plasmodium falciparum parasite, which was called RTS, S when it was experimental and which now has the brand name Mosquirix. The European Medicines Agency has approved it for use in children 6 weeks to 17 months old.