Page 168 - Medical Parasitology_ A Textbook ( PDFDrive )

14 Case Reports 161

Case 5: Plasmodium knowlesi Reinfection in Human
Case report: A 41-year-old Chinese man from Peninsular Malaysia was first admit-
ted to the hospital in October 2009 with a 4-day history of fever, chills and head-
ache. His symptoms started 2 weeks after a camping trip in the jungle in Raub,
Pahang. Initial examination showed thrombocytopaenia and hepatitis, and
Plasmodium knowlesi malaria was subsequently confirmed with nested PCR. He
recovered fully after a treatment course of oral quinine plus doxycycline.
The patient was readmitted to the hospital on June 11, 2010, with a 5-day history
of fever, chills and rigors, followed by epigastric pain, nausea and vomiting. His
symptoms began 15 days after another camping trip in a jungle in Tanjung Malim,
Perak. Laboratory investigations showed severe thrombocytopaenia. Falciparum
malaria was diagnosed initially on the basis of blood film microscopic examination
with 1% parasitaemia. The patient was administered oral mefloquine (750 mg) fol-
lowed by 500 mg and 250 mg at 6 h and 12 h, respectively. His parasitaemia level
increased from 1.0 to 2.5% despite treatment. Oral quinine and doxycycline were
initiated. However, renal function deteriorated and acute haemolysis was evident.
Oral quinine was changed to intravenous quinine and oral riamet was added.
Haemodialysis was initiated, and 1 unit each of packed erythrocyte cells and whole
blood were transfused. Parasitaemia eventually cleared on June 16, 2010. PCR done
later on patient’s blood sample confirmed P. knowlesi infection. PCR genotyping
indicates reinfection rather than recrudescence.

Source: Lau, Yee Ling, Lian Huat Tan, Lit Chein Chin, Mun Yik Fong, Mydin
Abdul-Aziz Noraishah, and Mahmud Rohela. “Plasmodium knowlesi reinfection
in human.” Emerging Infectious Diseases 17, no. 7 (2011): 1314.

Learning Points
1. In the early stage of P. knowlesi infection, the parasite morphology cannot be
distinguished from that of P. falciparum.
2. In knowlesi malaria, patients can rapidly progress to severe malaria due to the
quotidian (24 h) erythrocytic cycle of the parasite.
3. Early diagnosis and treatment of severe malaria with IV anti-malarial therapy is
important to prevent complications and death.
4. Plasmodium knowlesi infection does not cause relapse because the parasite has
no liver hypnozoite stage.

Case 6: Severe Plasmodium knowlesi Infection
Case report 1: A 50-year-old gentleman with no known medical history presented
to a district hospital with fever and rigors and a 3-day history of cough. On examina-
tion, he was alert and orientated but hypotensive (blood pressure 83/51 mmHg) and
hypoxic (oxygen saturation 70% on 10 L oxygen via high flow mask), rhonchi was
noted on chest auscultation. Otherwise, other systems were unremarkable. Blood
film for malaria parasite (BFMP) done was reported as Plasmodium malariae ‘4+’.
The patient was commenced on intravenous fluids, antibiotics and oral chloroquine,
and transferred to a general hospital. He deteriorated rapidly needing intubation and
ventilation and was commenced on inotropic support. Chest radiograph showed