Symptoms of malaria

• Its vague, flu-like symptoms may initially appear to be signs of a mild, self-limited viral infection for several days. • The prolonged incubation period means that if you have had exposure to malaria through a mosquito bite, you would not experience symptoms for several weeks or months, often after exposure to a tropical climate and its mosquitos is forgotten. PCR can detect the presence of the malaria parasite’s genetic material in a blood sample taken from an infected person. It is considered a highly sensitive test, but results may take several days. However, this test is not readily available and is primarily used for research purposes. The test requires a specialized laboratory facility and is more costly than other standard blood tests for malaria. In some circumstances, such as with cerebral malaria—a serious complication in which malaria spreads to the brain—non-invasive tests such as brain CT or MRI can be helpful. In those cases, imaging of the brain can show the presence of brain swelling, as well as areas of small hemorrhages and strokes, for which follow-up treatment strategies can be administered. These imaging tests will not be specific enough to diagnose malaria by themselves. Enteric fever is diagnosed via blood and stool testing and causes anemia and liver abnormalities on laboratory examination. Malaria is diagnosed by visualization of the malaria parasite on a microscopic blood smear. The infectious cause is different, and the infections require diff...

Each year, malaria causes an estimated 500,000 deaths worldwide. Most of these deaths occur in Africa and disproportionally affect children younger than five years worldwide. Human malarial disease is caused by protozoan parasites of the genus Plasmodium. The primary means of infection is through the bite of a female Anopheles mosquito. The incidence of malaria in the United States has increased since 2011, in conjunction with the increase in worldwide travel. An estimated 2,000 cases of malaria occur annually in the United States. All travelers to malaria-endemic regions should be prescribed prophylaxis. Malaria has a broad range of clinical presentations. Travelers who have symptoms of malaria should seek medical attention as soon as possible. All febrile travelers who have recently returned from a malarious area should be evaluated for malaria. The accurate, timely, and species-specific diagnosis of malaria is essential for successful treatment. Direct microscopy of Giemsa-stained blood smears is the reference standard for laboratory diagnosis. Rapid testing for malaria has emerged as an important adjunctive diagnostic modality. Malaria treatment is determined by individual patient factors and geography. The World Health Organization recommends treating uncomplicated cases of malaria with artemisinin combination therapy, except in the first trimester of pregnancy. Severe malaria is mainly caused by Plasmodium falciparum. Children, pregnant patients, and people who are n...

Overview Dengue (DENG-gey) fever is a mosquito-borne illness that occurs in tropical and subtropical areas of the world. Mild dengue fever causes a high fever and flu-like symptoms. The severe form of dengue fever, also called dengue hemorrhagic fever, can cause serious bleeding, a sudden drop in blood pressure (shock) and death. Millions of cases of dengue infection occur worldwide each year. Dengue fever is most common in Southeast Asia, the western Pacific islands, Latin America and Africa. But the disease has been spreading to new areas, including local outbreaks in Europe and southern parts of the United States. Researchers are working on dengue fever vaccines. For now, in areas where dengue fever is common, the best ways to prevent infection are to avoid being bitten by mosquitoes and to take steps to reduce the mosquito population. Symptoms Many people experience no signs or symptoms of a dengue infection. When symptoms do occur, they may be mistaken for other illnesses — such as the flu — and usually begin four to 10 days after you are bitten by an infected mosquito. Dengue fever causes a high fever — 104 F (40 C) — and any of the following signs and symptoms: • Headache • Muscle, bone or joint pain • Nausea • Vomiting • Pain behind the eyes • Swollen glands • Rash Most people recover within a week or so. In some cases, symptoms worsen and can become life-threatening. This is called severe dengue, dengue hemorrhagic fever or dengue shock syndrome. Severe dengue hap...

malaria, serious relapsing infection in humans, Anopheles mosquitoes. Malaria can occur in temperate regions, but it is most common in the tropics and subtropics. In many parts of sub-Saharan In the early 21st century the In 2021 China became the 40th country to be officially declared free of malaria by WHO—by far the most populous country worldwide to have been granted the The course of the disease Plasmodium vivax, malaria parasite Malaria in humans is caused by five related P. vivax. The deadliest is P. falciparum. In 2008 P. knowlesi, which was thought to infect primarily Old World P. knowlesi was found to be easily confused with P. malariae during microscopic examination, resulting in many cases being P. malariae when in fact they may have been caused by P. knowlesi. Anopheles mosquito Most merozoites reproduce asexually—that is, by making identical copies of themselves rather than by mixing the genetic material of their parents. A few, however, develop into a sexual stage known as a ookinetes; these embed themselves in the mosquito’s gut, where they mature after 9 to 14 days into Get a Britannica Premium subscription and gain access to exclusive content. Typically, victims who are bitten by tertian malaria) or 72 hours ( quartan malaria), coincide with the synchronized release of each new generation of merozoites into the bloodstream. Often, however, a victim may be infected with different species of parasites at the same time or may have different generations of the...