Malaria

Malaria is a mosquito-borne disease caused by a parasite. People with malaria often experience fever, chills, and flu-like illness. Left untreated, they may develop severe complications and die. Each year 350-500 million cases of malaria occur worldwide, and over one million people die, most of them young children in sub-Saharan Africa.

This sometimes fatal disease can be prevented and cured. Bednets, insecticides, and antimalarial drugs are effective tools to fight malaria in areas where it is transmitted. Travelers to a malaria-risk area should avoid mosquito bites and take a preventive antimalarial drug.

Infection with malaria parasites may result in a wide variety of symptoms, ranging from absent or very mild symptoms to severe disease and even death. Malaria disease can be categorized as uncomplicated or severe (complicated) . In general, malaria is a curable disease if diagnosed and treated promptly and correctly.

Incubation Period

Following the infective bite by the Anopheles mosquito, a period of time (the "incubation period") goes by before the first symptoms appear. The incubation period in most cases varies from 7 to 30 days. The shorter periods are observed most frequently with P. falciparum and the longer ones with P. malariae.

Antimalarial drugs taken for prophylaxis by travelers can delay the appearance of malaria symptoms by weeks or months, long after the traveler has left the malaria-endemic area. (This can happen particularly with P. vivax and P. ovale, both of which can produce dormant liver stage parasites; the liver stages may reactivate and cause disease months after the infective mosquito bite.)

Such long delays between exposure and development of symptoms can result in misdiagnosis or delayed diagnosis because of reduced clinical suspicion by the health-care provider. Returned travelers should always remind their health-care providers of any travel in malaria-risk areas during the past 12 months.

Uncomplicated Malaria

The classical (but rarely observed) malaria attack lasts 6-10 hours. It consists of:

• a cold stage (sensation of cold, shivering)
• a hot stage (fever, headaches, vomiting; seizures in young children)
• and finally a sweating stage (sweats, return to normal temperature, tiredness)

Classically (but infrequently observed) the attacks occur every second day with the "tertian" parasites (P. falciparum, P. vivax, and P. ovale) and every third day with the "quartan" parasite (P. malariae).

More commonly, the patient presents with a combination of the following symptoms:

• Fever
• Chills
• Sweats
• Headaches
• Nausea and vomiting
• Body aches
• General malaise.

In countries where cases of malaria are infrequent, these symptoms may be attributed to influenza, a cold, or other common infections, especially if malaria is not suspected. Conversely, in countries where malaria is frequent, residents often recognize the symptoms as malaria and treat themselves without seeking diagnostic confirmation ("presumptive treatment").

Physical findings may include:

• Elevated temperature
• Perspiration
• Weakness
• Enlarged spleen.

In P. falciparum malaria, additional findings may include:

• Mild jaundice
• Enlargement of the liver
• Increased respiratory rate.

Diagnosis of malaria depends on the demonstration of parasites on a blood smear examined under a microscope. In P. falciparum malaria, additional laboratory findings may include mild anemia, mild decrease in blood platelets (thrombocytopenia), elevation of bilirubin, elevation of aminotransferases, albuminuria, and the presence of abnormal bodies in the urine (urinary "casts").

Severe Malaria

Severe malaria occurs when P. falciparum infections are complicated by serious organ failures or abnormalities in the patient's blood or metabolism. The manifestations of severe malaria include:

• Cerebral malaria, with abnormal behavior, impairment of consciousness, seizures, coma, or other neurologic abnormalities
• Severe anemia due to hemolysis (destruction of the red blood cells)
• Hemoglobinuria (hemoglobin in the urine) due to hemolysis
• Pulmonary edema (fluid buildup in the lungs) or acute respiratory distress syndrome (ARDS), which may occur even after the parasite counts have decreased in response to treatment
• Abnormalities in blood coagulation and thrombocytopenia (decrease in blood platelets)
• Cardiovascular collapse and shock

Other manifestations that should raise concern are:

• Acute kidney failure
• Hyperparasitemia, where more than 5% of the red blood cells are infected by malaria parasites
• Metabolic acidosis (excessive acidity in the blood and tissue fluids), often in association with hypoglycemia
• Hypoglycemia (low blood glucose). Hypoglycaemia may also occur in pregnant women with uncomplicated malaria, or after treatment with quinine.

Severe malaria occurs most often in persons who have no immunity to malaria or whose immunity has decreased. These include all residents of areas with low or no malaria transmission, and young children and pregnant women in areas with high transmission.

In all areas, severe malaria is a medical emergency and should be treated urgently and aggressively.

Malaria Relapses

In P. vivax and P. ovale infections, patients having recovered from the first episode of illness may suffer several additional attacks ("relapses") after months or even years without symptoms. Relapses occur because P. vivax and P. ovale have dormant liver stage parasites ("hypnozoites") that may reactivate. Treatment to reduce the chance of such relapses is available and should follow treatment of the first attack.

Other Manifestations of Malaria

• Neurologic defects may occasionally persist following cerebral malaria, especially in children. Such defects include troubles with movements (ataxia), palsies, speech difficulties, deafness, and blindness.
• Recurrent infections with P. falciparum may result in severe anemia. This occurs especially in young children in tropical Africa with frequent infections that are inadequately treated.
• Malaria during pregnancy (especially P. falciparum) may cause severe disease in the mother, and may lead to premature delivery or delivery of a low-birth-weight baby.
• On rare occasions, P. vivax malaria can cause rupture of the spleen or acute respiratory distress syndrome (ARDS).
• Nephrotic syndrome (a chronic, severe kidney disease) can result from chronic or repeated infections with P. malariae.
• Hyperreactive malarial splenomegaly (also called "tropical splenomegaly syndrome") occurs infrequently and is attributed to an abnormal immune response to repeated malarial infections. The disease is marked by a very enlarged spleen and liver, abnormal immunologic findings, anemia, and a susceptibility to other infections (such as skin or respiratory infections).

Overview

Malaria must be recognized promptly in order to treat the patient in time and to prevent further spread of infection in the community.

Malaria can be suspected based on the patient's symptoms and the physical findings at examination. However, for a definitive diagnosis to be made, laboratory tests must demonstrate the malaria parasites or their components.

Malaria is a disease transmitted by the bite of infected Anopheles mosquitoes. In spite of India's National Malaria Eradication programme, this disease which had been under control has suddenly made a comeback. The resurgence of malaria is now a heavy burden on India. Most American cases of malaria develop in travelers who have recently returned from parts of the world where malaria is widespread. These prophylactic drug treatments are simply too expensive for most people living in endemic areas. Malaria infections are treated through the use of antimalarial drugs , such as chloroquine or pyrimethamine , although drug resistance is increasingly common. 

Malaria is an infectious disease that is widespread in tropical and subtropical regions. Approximately 300 million people worldwide are affected by malaria and between 1 and 1.5 million people die from it every year. Malaria is endemic in parts of Asia, Africa, Central and South America, Oceania, and certain Caribbean islands. Of these areas, sub-Saharan Africa has the highest occurrence of P falciparum transmission to travelers from the US. Malaria-carrying Anopheles species mosquitoes tend to bite only between dusk and dawn. Malaria is one of the most common infectious diseases and an enormous public-health problem. Malaria remains one of the world's leading infectious killers, particularly of children in sub-Saharan Africa. The disease is caused by protozoan parasites of the genus Plasmodium. 

Malaria is the most deadly vector borne disease in the world. Malaria is an infection of the blood that is carried from person to person by mosquitoes. Each year in the U.S., there are an average of 1000 imported infections; a few cases of locally acquired, mosquito-transmitted infection from an imported case; and an average of four deaths from falciparum malaria. The parasites multiply within red blood cells , causing symptoms that include fever , anemia , chills , flu-like illness , and in severe cases, coma and death. Malaria-causing Plasmodium species metabolize hemoglobin and other RBC proteins to create a toxic pigment termed hemozoin . 

Causes of Malaria 

The common Causes of Malaria : 

• This species, found mostly in tropical areas of Asia, produces less severe symptoms but can remain in   your liver and cause relapses for up to three years. 
• If this kind of infection goes untreated, it usually lasts for 2-3 months with diminishing frequency and intensity of paroxysms of patients infected with P vivax, 50% experience a relapse in a few weeks to 5 years after the initial illness. 
• Infection with any of these three types of malaria usually is not life-threatening, and a person may recover in a month without treatment. 
• Those infected with this species of Plasmodium remain asymptomatic for a much longer period of time than those infected with P vivax or P ovale recrudescence is common in those infected with P malariae .