Malaria A017

Current RMA Instruments

Changes from previous Instruments

ICD Coding

• ICD-10-AM Codes: B50, B51, B52, B53, B54

Brief description

Malaria is an infection caused by Plasmodium parasites, transmitted to humans through the bite of an infected mosquito. For the purposes of this SOP, malaria includes infection with the human malaria species:

• Plasmodium falciparum
• Plasmodium vivax
• Plasmodium ovale
• Plasmodium malariae

as well as infection with Plasmodium knowlesi and other simian (monkey-associated) malaria species. 

Malaria is most commonly acquired in tropical and subtropical regions, particularly in parts of Africa, Asia and South America. 

The condition typically presents with a flu-like illness, including fever, chills, sweats, headache, body aches, nausea, and general malaise. Physical findings may include weakness, anaemia, and enlargement of the liver or spleen, and in more severe cases, jaundice or organ dysfunction. 

Some forms of malaria, particularly Plasmodium vivax and Plasmodium ovale, may relapse months or years after the initial infection due to dormant parasites in the liver. 

Confirming the diagnosis

Malaria may be suspected based on clinical features and a history of potential exposure in an endemic area. Confirmation requires laboratory testing, most commonly:

• microscopy of a stained blood smear, demonstrating malaria parasites, or
• rapid diagnostic tests (RDTs) detecting malaria antigens

Identification of the specific Plasmodium species is important, as this may affect both treatment and application of SOP factors. 

Assessment and management are typically undertaken by an infectious diseases physician. 

Additional diagnoses covered by SOP

• Plasmodium falciparum infection
• Plasmodium knowlesi infection
• Plasmodium malariae infection
• Plasmodium ovale infection
• Plasmodium vivax infection
• Other simian malaria infections

Clinical onset

Malaria typically presents within days to weeks after exposure, most commonly within one month, although onset may be delayed in some cases.

Early symptoms are often non-specific, resembling a flu-like illness. A cyclical pattern of fever with chills and sweats may occur, depending on the infecting species. 

Once the diagnosis is confirmed, clinical onset may be backdated to the time when symptoms and signs consistent with malaria were first present. A recurrence of symptoms after a symptom-free period may represent:

• relapse (seen with P.vivax or P.ovale, due to dormant liver stages, often within 2-3 years)
• recrudescence due to incomplete treatment (typically within 6 months) or
• a new infection

Plasmodium falciparum and P. malariae do not relapse. 

Clinical worsening

Malaria can lead to serious complications as part of its natural course, particularly in infections with Plasmodium falciparum. These may include severe anaemia, organ failure or death. Clinical worsening at the time of initial presentation is generally considered part of the natural progression of untreated or severe disease, rather than a separate worsening factor. Clinical worsening may be relevant in cases of relapsing or recurrent disease, particularly where there is failure to achieve appropriate treatment or follow-up. With timely and appropriate treatment, the usual course of malaria is complete recovery.