National case definition: Malaria

Malaria

Date of last revision/review: May 2008

National notification

Only confirmed cases of disease should be notified.

Type of surveillance

Routine case-by-case notification to the federal level

Case classification

Confirmed case

Laboratory confirmation of infection with or without clinical evidence of infection:

• demonstration of Plasmodium sp. in a blood smear/film (thick and thin)

Probable case

Laboratory confirmation of infection with or without clinical evidence of infection:

• detection of Plasmodium sp. antigen in an appropriate clinical specimen

It should be noted that

• A case is counted if it is the individual's first attack of malaria in Canada, regardless of whether or not she/he has experienced previous attacks of malaria outside the country.
• A subsequent attack in the same person caused by a different Plasmodium species is counted as an additional case.
• A repeat attack by the same species is not counted as a new case unless the person has traveled to a malaria-endemic area since the previous attack.

Clinical evidence

Signs and symptoms vary; however, most patients experience fever. In addition to fever, common associated symptoms include headache, back pain, chills, sweats, myalgia, nausea, vomiting, diarrhea and cough. Severe untreated malaria can lead to coma, seizures, renal failure, pulmonary edema and death.

ICD code(s)

ICD-10 code(s): B50, B51, B52, B53, B54

ICD-9 code(s): 084

Type of international reporting

Elimination or eradication efforts should be reported.

Comments

Malaria cases are subdivided into the following categories:

• Induced:a confirmed case of malaria acquired through a blood transfusion from a donor in whom the parasite has been confirmed.
• Autochthonous:a confirmed case of malaria acquired by mosquito transmission within Canada.
• Imported: a confirmed case of malaria acquired outside Canada.
• Congenital, confirmed: a confirmed case of malaria in an infant < 3 months old who has not left Canada since birth, with confirmation of the presence of the parasite in the mother.
• Congenital, probable: a confirmed case of malaria in an infant < 3 months old who has not left Canada since birth, but without demonstration of the presence of the parasite in the mother.

It should be noted that the WHO requires different case classification. In areas with access to laboratory-based diagnosis, the WHO classifies malaria case as asymptomatic malaria, confirmed uncomplicated malaria, confirmed severe malaria and confirmed malaria death.

Probable case definitions are provided as guidelines to assist with case finding and public health management, and are not for national notification purposes.

References

Case definitions for diseases under national surveillance. CCDR 2000;26(S3).

Retrieved May 2008, from http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/00vol26/26s3/index.html

Centers for Disease Control and Prevention. Case definitions for infectious conditions under public health surveillance. MMWR 1997;46(No. RR-10):22-3.

World Health Organization. Department of Communicable Disease Surveillance and Response (October 1999). WHO Recommended Surveillance Standards. 2nd ed. WHO/CDS/CSR/ISR/99.2. Retrieved May 29, 2007, from www.who.int/csr/resources/publications/surveillance/whocdscsrisr992.pdf