Quaternary (quartan) malaria is the form caused mainly by Plasmodium malariae and transmitted by Anopheles mosquitoes. It causes cyclical fevers every ~72 hours, typically with low parasite levels and potential chronic infection that can affect the kidneys (nephrotic syndrome). Diagnosis is by blood smear or rapid tests; treatment uses antimalarials (commonly chloroquine for non-falciparum infections) and follow-up.

The four main types of malaria are caused by Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae. P. falciparum is the most severe and can be life‑threatening. P. vivax and P. ovale can form dormant liver stages causing relapses. P. malariae typically causes milder, longer‑lasting low‑grade infections. Diagnosis and treatment vary by species and should be guided by medical professionals.

4‑Aminoquinolines are a class of antimalarial drugs (e.g., chloroquine, amodiaquine) used to treat and prevent malaria caused by sensitive Plasmodium species. They concentrate in the parasite’s food vacuole, blocking heme detoxification and killing the parasite. Resistance is widespread in Plasmodium falciparum. Common adverse effects include gastrointestinal upset, skin reactions, and rare retinal or cardiac toxicity with prolonged or high‑dose use.

The four clinical stages of malaria are: incubation — asymptomatic period after the mosquito bite while parasites multiply in the liver; prodromal — nonspecific symptoms (headache, malaise, myalgia) as blood infection begins; paroxysmal/acute — cyclic fever, chills, sweating and anemia from red cell rupture; convalescence — recovery, though relapses can occur with some species (e.g., P. vivax).

Plasmodium falciparum is the deadliest malaria species. It causes rapid high-level parasitemia and severe complications—cerebral malaria, severe anemia, respiratory distress, and multi-organ failure—leading to most malaria deaths, especially among young children and pregnant women in sub-Saharan Africa. Prompt diagnosis and artemisinin-based combination treatment, plus prevention (nets, spraying, chemoprophylaxis, vaccination where available), greatly reduce mortality.

"Quartan" describes a pattern of periodic symptoms—classically fever—that recur every 72 hours (often called "every fourth day" when days are counted inclusively). It’s most associated with quartan malaria caused by Plasmodium malariae, where febrile paroxysms follow this cycle. The term can apply to other conditions showing the same three-day interval between attacks.