Malaria is an infectious disease caused by a parasite, Plasmodium, which infects red blood cells. Malaria is characterized by cycles of chills, fever, pain, and sweating. Historical records suggest malaria has infected humans since the beginning of mankind. The name “mal aria” (meaning “bad air” in Italian) was first used in English in 1740 by H. Walpole when describing the disease. The term was shortened to “malaria” in the 20th century. C. Laveran in 1880 was the first to identify the parasites in human blood. In 1889, R. Ross discovered that mosquitoes transmitted malaria. Of the four common species that cause malaria, the most serious type is Plasmodium falciparum malaria.Malaria transmission can be reduced by preventing mosquito bites by distribution of inexpensive mosquito nets and insect repellents, or by mosquito-control measures such as spraying insecticides inside houses and draining standing water where mosquitoes lay their eggs. Although many are under development, the challenge of producing a widely available vaccine that provides a high level of protection for a sustained period is still to be met.[3] Two drugs are also available to prevent malaria in travellers to malaria-endemic countries (prophylaxis).
Causes,Risk Factors:
Malaria is caused by a parasite that is transmitted from one human to another by the bite of infected Anopheles mosquitoes. In humans, the parasites (called sporozoites) travel to the liver, where they mature and release another form, the merozoites. These enter the bloodstream and infect the red blood cells.
The parasites multiply inside the red blood cells, which then rupture within 48 to 72 hours, infecting more red blood cells. The first symptoms usually occur 10 days to 4 weeks after infection, though they can appear as early as 8 days or as long as a year after infection. Then the symptoms occur in cycles of 48 to 72 hours.
The majority of symptoms are caused by the massive release of merozoites into the bloodstream, the anemia resulting from the destruction of the red blood cells, and the problems caused by large amounts of free hemoglobin released into circulation after red blood cells rupture.
Malaria can also be transmitted from a mother to her unborn baby (congenitally) and by blood transfusions. Malaria can be carried by mosquitoes in temperate climates, but the parasite disappears over the winter.
The disease is a major health problem in much of the tropics and subtropics. The CDC estimates that there are 300-500 million cases of malaria each year, and more than 1 million people die. It presents a major disease hazard for travelers to warm climates.
The symptoms characteristic of malaria include flulike illness with fever, chills, muscle aches, and headache. Some patients develop nausea, vomiting, cough, and diarrhea. Cycles of chills, fever, and sweating that repeat every one, two, or three days are typical. There can sometimes be vomiting, diarrhea, coughing, and yellowing (jaundice) of the skin and whites of the eyes due to destruction of red blood cells and liver cells.
People with severe P. falciparum malaria can develop bleeding problems, shock, liver or kidney failure, central nervous system problems, coma, and can die from the infection or its complications. Cerebral malaria (coma, or altered mental status or seizures) can occur with severe P. falciparum infection.
Clinical symptoms associated with travel to countries that have identified malarial risk (listed above) suggest malaria as a diagnosis. Malaria tests are not routinely ordered by most physicians so recognition of travel history is essential. Unfortunately, many diseases can mimic symptoms of malaria (for example, yellow fever, dengue fever, typhoid fever, cholera, filariasis, and even measles and tuberculosis). Consequently, physicians need to order the correct special tests to diagnose malaria, especially in industrialized countries where malaria is seldom seen. Without the travel history, it is likely that other tests will be ordered initially. In addition, the long incubation periods may tend to allow people to forget the initial exposure to infected mosquitoes.
The classic and most used diagnostic test for malaria is the blood smear on a microscope slide that is stained (Giemsa stain) to show the parasites inside red blood cells.
  • Destruction of blood cells (hemolytic anemia)
  • Liver failure and kidney failure
  • Meningitis
  • Respiratory failure from fluid in the lungs (pulmonary edema)
  • Rupture of the spleen leading to massive internal bleeding (hemorrhage).
Malaria, especially Falciparum malaria, is a medical emergency requiring hospitalization. Chloroquine is a frequently used anti-malarial medication, but quinidine or quinine plus doxycycline, tetracycline, or clindamycin; or atovaquone plus proguanil (Malarone); or mefloquine or artesunate; or the combination of pyrimethamine and sulfadoxine, are given for chloroquine-resistant infections. The choice of medication depends in part on where you were when you were infected.
Aggressive supportive medical care, including intravenous (IV) fluids and other medications and breathing (respiratory) support may be needed.
It is important to see your health care provider well before your trip, because treatment may begin is long as 2 weeks before travel to the area, and continue for a month after you leave the area. The types of anti-malarial medications prescribed will depend on the area you visit. According to the CDC, travelers to South America, Africa, the Indian subcontinent, Asia, and the South Pacific should take one of the following drugs: mefloquine, doxycycline, choroquine, hydroxychoroquine, or Malarone.
Even pregnant women should take preventive medications because the risk to the fetus from the medication is less than the risk of acquiring a congenital infection.
People on anti-malarial medications may still become infected. Avoid mosquito bites by wearing protective clothing over the arms and legs, using screens on windows, and using insect repellent.
Chloroquine has been the drug of choice for protection from malaria. But because of resistance, it is now only suggested for use in areas where Plasmodium vivax, P. oval, and P. malariae are present. Falciparum malaria is becoming increasingly resistant to anti-malarial medications.
For travelers going to areas where Falciparum malaria is known to occur, there are several options for malaria prevention, including mefloquine, atovaquone/Proguanil (Malarone), and doxycycline.
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