Malaria is a major cause of death worldwide and is brought about by the protozoan parasite Plasmodium acquired from a bite of a female Anopheles mosquito carrier. Malaria are still endemic in warm climates and in most third world countries around the globe. It is essentially non-existent in highly developed and first world countries like the United States and Europe.
The typical malaria infection will present with recurrent attacks of high grade fever with moderate to severe chills. Patients will also present with profuse diaphoresis (sweating) as the core body temperature drops. Other common signs and symptoms of malaria include vomiting, headache, and diarrhea. These signs usually develop within a few weeks from the mosquito bite; however, some parasites may lie dormant within the blood stream for months to years.
A detailed clinical history of the patient with a history of travel in malaria endemic areas would usually clinch the diagnosis. Blood tests are paramount in the diagnosis of malarial diseases. Malarial peripheral smears can demonstrate whether the host is infected, what particular plasmodium strain is causing the infection, whether malarial infections have affected other bodily organs, and resistant strains to certain anti-malarial drugs.
In cases of malarial infections, the choice of anti-malarial drug and duration of treatment are heavily dependent on the type of etiologic agent, severity of the symptomatology, age of patients and whether the patient is pregnant. The following anti-malarial agents are commonly used to treat malaria.
High doses of quinine and chloroquine may cause complications of methemoglobinemia among patients; thus, frequent blood monitoring is imperative .
The majority of uncomplicated malarial cases carries a good prognosis with early treatment. Patients who are treated early will usually show signs of marked improvement in the signs and symptoms. An afebrile period of more than 96 hours after 48 hours from the start of antimalarial treatment is good prognostic indicator. Infections with Plasmodium falciparum especially with complications spell out a grimmer prognosis with relatively high mortality rates if left untreated.
Cerebral malaria is the most common cause of deaths among children and adult patients. Even with adequate medications and treatment, cerebral malaria carries a mortality rate of 15 to 20% in most cases. Patients with hemoglobinopathies like sickle cell anemia, Thalassemia, and Hemoglobin C have an inherent resistance to P. vivax and P. falciparum infections and complications . However, they may not be immune to Plasmodium parasitemia which usually confers no significant medical signs and symptoms.
There are at least five Plasmodium species that cause human malaria, these are: Plasmodium falciparum, Plasmodium malariae, Plasmodium vivax, Plasmodium ovale, and Plasmodium knowlesi . The prevalence of the etiologic agents vary from region to region of endemicity where hosts are usually infected by a singles species of Plasmodium at a time. In 5% to 7% of cases, multiple species of the Plasmodium parasites can infect a human host at the same time . Different species of malaria may have a different incubation period varying from 2 to 4 weeks that is why malarial prophylaxis is continually given for weeks after the traveler has returned home from a malaria infected region.
In the United States, isolated cases of malaria are predominantly imported from other tropical and subtropical countries because they have successfully eradicated the parasite during the 19th century until the turn of the 20th century . Although, recent CDC reports as of 2010 have shown an increase of approximately 14% compared to the 2009 malaria census which are largely due to airport passenger transmissions . The massive death annual death toll that reaches more than a million cases on malaria are predominantly seen among the children from the sub-saharan regions of Africa and are usually caused by the P. falciparum species. The life threatening malarial infections has been amply documented to reach approximately 300 to 500 Million infections per year worldwide .
There are no sexual predilection for malarial infections. Infected mothers may result to fetal complications like anemia, low-birth weight, premature birth, and death. Maternal malarial infection during the first trimester of pregnancy often results to abortion or miscarriage .
After the infected female Anopheles mosquito takes her blood meal on the human skin, she injects up to 15 malarial sporozoites in the blood stream which rapidly enter the liver cells. The sporozoites then undergoes rapid reproduction in the hepatocytes by asexual fission to form the pre-erythrocytic schizonts. The malarial merozoites multiply by the thousands within the hepatocyte schizont until they are released to the blood stream to attach to red blood cells. The merozoites may rapidly reproduce within the erythrocytes to form malarial trophozoites where red blood cell (rbc) rupture takes place after the schizont is filled and a new set of merozoites is released in the blood stream to infect a new sets of rbc.
The erythrocyte rupture and the progressive anemia causes the main presentation in malaria. The erythrocytic rupture releases toxins to the blood stream and induces cytokine release from macrophages causing the distinct fever and chills in the patients. Patients with heavy hepatocyte load may present with hepatomegaly. Larger merozoites in the blood develop to either male or female gametocytes which are ingested by the mosquito through a blood meal where they sexually reproduce within the mosquito vectors. The same cycle repeats in every human and mosquito infection encountered.
The most effective way to prevent malaria is to avoid visiting regions with known malarial endemicity. When visits becomes unavoidable, adequate drug prophylaxis should be taken at the prescribed period before the trip to avoid parasitic infections. Patients suspecting malaria infections should opt for prompt medical attention and treatment to prevent serious complications.
Malaria is a parasitic infection that causes recurrent attacks of fever and chills. Malaria claims approximately 1 million lives annually on a worldwide scale. Because many malarial strains are now immune to common anti-malarial drugs, it is most prudent to take drug prophylaxis before travelling to tropical and subtropical countries where malaria is still endemic. Current researche on malaria is focusing on the development of a vaccine to eradicate this worldwide menace .
The five Plasmodium parasite species (P. falciparum, P. malariae, Plasmodium vivax, P. ovale, and P. knowlesi) cause malaria.
Diagnosis is made by demonstration of the Plasmodium merozoite or trophozoite in the blood from blood smears.
Treatment and follow-up
Anti-malarial agentsare Quinine sulfate, Chloroquine, Hydroxychloroquine, Mefloquine, Malarone and Primaquine.