Plasmodium knowlesi

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Record number: 
Adverse Occurrence type: 
MPHO Type: 
Estimated frequency: 
Rarely described transfusion-transmitted infection; a review published in 2018 (Verra et al) stated that amongst 100 transfusion-transmitted malaria reports, 2% were due to P. knowlesi.
Time to detection: 
11 days
Alerting signals, symptoms, evidence of occurrence: 
A 23-year old splenectomized female patient with beta thalassaemia major presented with fever, headache and dizziness 11 days after receiving a blood transfusion. She lived in a malaria endemic area in Sabah, Malaysia; she developed metabolic acidosis and multi-organ failure. A blood film taken on arrival was positive for malaria parasites resembling P. knowlesi, with a parasite count of 84,000 parasites/µL. She responded well to intravenous artesunate and recovered. High parasite counts and severe disease with P. knowlesi usually occur in elderly patients, but the severity of presentation was likely linked to the asplenia in this young adult; mode of acquisition of infection might have played a role too. A species specific PCR was performed and confirmed the diagnosis. The blood donor was a 51-year old male farmer who lived in a malaria-endemic area and was asymptomatic on the day of donation but presented to medical care 12 days later with a 5 day history of fever, nausea, headache and malaise. P. falciparum were reported from a blood film but a PCR performed retrospectively confirmed P. knowlesi infection. Blood film microscopy of blood donor sample is used in Malaysia at the time of donation but this is not sufficienlty sensitive to detect low level asymptomatic parasitemia, as in this case.
Demonstration of imputability or root cause: 
Sequencing of a highly diverse 649-base pair fragment of the P. knowlesi bifunctional dihydrofolate reductase-thymidylate synthase gene (pkdhfr) revealed that the recipient and donor shared the same haplotype.
Imputability grade: 
3 Definite/Certain/Proven
Suggest new keywords: 
malaria, Plasmodium knowlesi, fever, metabolic acidosis, multi organ failure, beta thalassaemia major, asplenia, headache, nausea, malaise, chills, blood film
Suggest references: 
- Bird, Elspeth M, et al. Transfusion-transmitted severe Plasmodium knowlesi malaria in a splenectomized patient with beta-thalassaemia major in Sabah, Malaysia: a case report. Malar J. 2016 Jul 12;15(1):357 - Verra F. et al, A systematic review of transfusion-transmitted malaria in non-endemic areas, Malar J. 2018 Jan 16;17(1):36
Is this "Traipattanakul J, Changpradub D, Trakulhun K, Phiboonbanakit D, Mungthin M. A first case of Plasmodium knowlesi malaria in Phramongkutklao Hospital. Journal of Infectious Diseases and Antimicrobial Agents. 2014;31:91–100." already i the library? Ines No we don't, I have added the pdf here (EP)
Expert comments for publication: 
Human infections with P. knowlesi (a simian malaria parasite) are more common then previously thought and can be clinically indistinguishable from P. falciparum malaria. P. knowlesi is present in South East Asia, and it may be mis-indentified microscopically; early trophozoites ressemble those of P. falciparum. Late and mature trophozoites, schizonts and gametocytes ressemble those of P. malariae. P. knowlesi has a 24 hour cycle and can reach high levels of parasitemia, with potential to cause severe disease; it requires early diagnosis and prompt treatment. A systematic review of transfusion-transmitted malaria has been published in 2018 (Verra et al).