Generality
Malaria is a disease caused by four distinct protozoa belonging to the genus Plasmodium, which are transmitted to humans through the bite of female mosquitoes of the genus Anopheles. These vector insects can become infected by stinging a sick individual and passing the infection to a healthy person with a second sting.
Symptoms
For further information: Malaria Symptoms
When an infected mosquito bites a healthy individual, the parasites enter the bloodstream, migrate to the liver and enter the hepatocytes, where they proliferate almost undisturbed.
After this period of active proliferation, which lasts approximately 2-4 weeks, the offspring parasites escape from the hepatic cells, invade the bloodstream and enter the red blood cells. Here they start to multiply again, until they are released externally, injuring the cell; the clinical signs of malaria are associated with this lesion, including febrile episodes (associated with cold attacks followed by profuse sweating, heat and intense thirst), anemia and an increase in the size of some organs (especially the spleen and liver). After exiting the erythrocytes, the new parasites invade other red blood cells, resuming a process that is repeated cyclically in waves (hence the particular course of febrile episodes), at least as long as the host's defensive processes do not interrupt it.
The interval between the different crises depends on the type of malaria, in turn determined by the causative agent that caused it; Plasmodium falciparum, Plasmodium vivax And Plasmodium ovale cause tertian malaria (in which febrile attacks are repeated every three days), while Plasmodium malariae it causes quartan malaria (in which febrile fits are repeated every four days).
Insights and Curiosities
Diagnosis
The diagnosis is based on the microscopic search for parasites in a blood sample taken (preferably) a few hours before the feverish attack.
Treatment
The preventive and curative therapy of malaria is carried out by administering appropriate drugs, such as chloroquine (often ineffective due to the presence of resistant parasites), quinine sulphate - hydrochloride and artemisinin derivatives; also important is environmental prophylaxis (draining of swamps, use of insecticides and larvicides on a large scale, elimination of water stagnation) and individual, both general (use of appropriate clothing, insect repellents and application of mosquito nets to windows and around the beds) and pharmacological (chemoprophylaxis with chloroquine or other antimalarial drugs is strongly recommended for non-immune subjects who go to endemic areas).
In individuals who overcome the disease there remains a "specific immunity for the plasmodium that caused malaria, even if that against Plasmodium falciparum disappears a few months after healing; This malarial form is - among other things - the most difficult to overcome, so much so that the clinical picture is often complicated until the patient's death. In any case, whatever the etiological agent involved, before complete recovery the disease often presents relapses with milder symptoms, even after months or even years.
Several malaria vaccines are currently in an advanced trial phase, with encouraging premises. One of these (Mosquirix ®) was approved by the "EMA - the European Medicines Agency - in July 2015.
Medicines for the treatment and prevention of Malaria "
