Malaria Disease

What is Malaria?

Malaria is a disease caused by a parasite that lives part of its life in humans and part in mosquitoes. Malaria remains one of the major killers of humans worldwide, threatening the lives of more than one-third of the world’s population. It thrives in the tropical areas of Asia, Africa, and Central and South America, where it strikes millions of people. Each year 350 to 500 million cases of malaria occur worldwide. Sadly, more than 1 million of its victims, mostly young children, die yearly.

Although malaria has been virtually eradicated in the United States and other regions with temperate climates, it continues to affect hundreds of people in this country every year. The Centers for Disease Control and Prevention (CDC) estimates 1,200 cases of malaria are diagnosed each year in the United States. People who live in the United States typically get malaria during trips to malaria-endemic areas of the world.


History of Malaria

Malaria has been around since ancient times. The early Egyptians wrote about it on papyrus, and the famous Greek physician Hippocrates described it in detail. It devastated invaders of the Roman Empire. In ancient Rome, as in other temperate climates, malaria lurked in marshes and swamps. People blamed the unhealthiness in these areas on rot and decay that wafted out on the foul air. Hence, the name is derived from the Italian, “mal aria,” or bad air. In 1880, the French scientist Alphonse Laveran discovered the real cause of malaria, the single-celled Plasmodium parasite. Almost 20 years later, scientists working in India and Italy discovered that Anopheles mosquitoes are responsible for transmitting malaria.

Historically, the United States is no stranger to the tragedy of malaria. This disease, then commonly known as “fever and ague,” took a toll on early settlers. Historians believe that the incidence of malaria in this country peaked around 1875, but they estimate that by 1914 more than 600,000 new cases still occurred every year.

Malaria has been a significant factor in virtually all of the military campaigns involving the United States. In World War II and the Vietnam War, more personnel time was lost due to malaria than to bullets.

The discovery that malaria was transmitted by mosquitoes unleashed a flurry of ambitious public health measures designed to stamp out malaria. These measures were targeted at both the larval stages (which thrive in still waters, such as swamps) and adult stages of the insect. In some areas, such as the southern United States, draining swamps and changing the way land was used was somewhat successful in eliminating mosquitoes.

The pace of the battle accelerated rapidly when the insecticide DDT and the drug chloroquine were introduced during World War II. DDT was remarkably effective and could be sprayed on the walls of houses where adult Anopheles mosquitoes rested after feeding. Chloroquine has been a highly effective medicine for preventing and treating malaria.

In the mid-1950s, the World Health Organization (WHO) launched a massive worldwide campaign to eliminate malaria. At the beginning, the WHO program, which combined insecticide spraying and drug treatment, had many successes, some spectacular. In some areas, malaria was conquered completely, benefiting more than 600 million people, and was sharply curbed in the homelands of 300 million others.

Difficulties soon developed, however. Some stumbling blocks were administrative, others financial. Even worse, nature intervened. More and more strains of Anopheles mosquitoes developed resistance to DDT and other insecticides, and the environmental impact of DDT was recognized. Meanwhile, the Plasmodium parasite became resistant to chloroquine, the mainstay of antimalarial drug treatment in humans.

Researchers estimate that infection rates increased by 40 percent between 1970 and 1997 in sub-Saharan Africa. To cope with this dangerous resurgence, public health workers carefully select prevention methods best suited to a particular environment or area. In addition to medicines and insecticides, they are making efforts to control mosquitoes, by draining swampy areas and filling them with dirt, as well as using window screens, mosquito netting, and insect repellents.

At the same time, scientists are intensively researching ways to develop better weapons against malaria, including
  • Sophisticated techniques for tracking disease transmission worldwide 
  • More effective ways of treating malaria 
  • New ways, some quite ingenious, to control transmission of malaria by mosquitoes
  • A vaccine for blocking malaria’s development and spread
Cause of Malaria 

Malaria


Malaria is caused by a single-celled parasite from the genus Plasmodium. More than 100 different species of Plasmodium exist. They produce malaria in many types of animals and birds, as well as in humans. 

Four species of Plasmodium commonly infect humans. Each one has a distinctive appearance under the microscope, and each one produces a somewhat different pattern of symptoms. Two or more species can live in the same area and infect a single person at the same time. 

Plasmodium falciparum is responsible for most malaria deaths, especially in Africa. The infection can develop suddenly and produce several life-threatening complications. With prompt, effective treatment, however, it is almost always curable. 

Plasmodium vivax, the most geographically widespread of the species, produces less severe symptoms. Relapses, however, can occur for up to 3 years, and chronic disease is debilitating. Once common in temperate climates, P. vivax is now found mostly in the tropics, especially throughout Asia. 

Plasmodium malariae infections not only produce typical malaria symptoms but also can persist in the blood for very long periods, possibly decades, without ever producing symptoms. A person with asymptomatic (no symptoms) P. malariae, however, can infect others, either through blood donation or mosquito bites. P. malariae has been wiped out from temperate climates, but it persists in Africa. 

Plasmodium ovale is rare, can cause relapses, and generally occurs in West Africa.

source (Meyda Azzahra)