Malaria

Question 1

how does malaria falciaprum appears on peripheral blood stain?

Answer 1

• RBCs not enlarged
• delicate ring trophozoites (headphone appearance)
• multiple trophoizoites possible in infected RBCs (multiple infection of single RBC)
• banana/ crescent shaped gametocyte
• schizonts rarely present in PBF

Question 2

how does malaria vivax appears on peripheral blood stain?

Answer 2

• RBCs enlarged
• Ameboid trophozoites: Can be difficult to ddx from P. ovale, but schizonts in vivax contain 12-24 merozoites, whereas ovale contains 8-12 merozoites
• round- oval gametocyte

Question 3

what are the different species of malaria?

Answer 3

• Four different Plasmodium species: P. falciparum, P. vivax, P. ovale and P. malariae.
• Another species, P. knowlesi usually infects non-human primates, but has occasionally infected humans and is capable of causing life-threatening complications and death.

Question 4

What is the incubation period for malaria?

Answer 4

Ranges from 7-30 days in most cases. Incubation period also varies according to species:
• P. falciparum: 9-14 days
• P. vivax and P. ovale: 12-18 days (up to 6-12 months for some P. vivax strains)
• P. malariae: 18–40 days
• P. knowlesi: 9-12 days

Question 5

what are the clinical features of uncomplicated malaria?

Answer 5

• Uncomplicated malaria is defined as symptomatic malaria parasitaemia without evidence of severe features or organ dysfunction.
• It commonly presents as an acute febrile illness.
• Symptoms include fever, chills, headache, myalgia, cough, vomiting, diarrhoea and abdominal pain.
• Febrile paroxysms occur every 48 hours in falciparum, vivax, ovale (although falciparum is more irregular); every 72 hours in malariae
• The initial phase can be non-specific and indistinguishable from other febrile illnesses.

Question 6

what are the clinical features of complicated malaria?

Answer 6

Severe malaria is life-threatening and there are signs of organ dysfunction
• impaired consciousness or unrousable coma
• prostration, i.e. generalized weakness so that the patient is unable walk or sit up without assistance
• failure to feed
• multiple convulsions – more than two episodes in 24 h
• deep breathing, respiratory distress (acidotic breathing)
• circulatory collapse or shock, systolic blood pressure < 70 mm Hg in adults and < 50 mm Hg in children
• clinical jaundice plus evidence of other vital organ dysfunction
• haemoglobinuria
• abnormal spontaneous bleeding
• pulmonary oedema (radiological)

Question 7

what are the laboratory features of complicated malaria?

Answer 7

• hypoglycaemia (blood glucose < 2.2 mmol/l or < 40 mg/dl)
• metabolic acidosis (plasma bicarbonate < 15 mmol/l)
• severe normocytic anaemia (Hb < 5 g/dl, packed cell volume < 15%)
• haemoglobinuria
• hyperparasitaemia (> 2%/100 000/μl in low intensity transmission areas or > 5% or 250 000/μl in areas of high stable malaria transmission intensity)
• hyperlactataemia (lactate > 5 mmol/l)
• renal impairment (serum creatinine > 265 μmol/l)

Question 8

what are the investigations needed for malaria?

Answer 8

• Examination of thick and thin blood films (repeat 12 hourly for 48 hours if the diagnosis is considered likely and initial films are negative).

• Thick smear: for detection (presence of Plasmodium)
• Thin smear: for speciation (identifying species of Plasmodium)
• Rapid diagnostic tests (RDTs) offer a useful alternative to microscopy in situations where reliable microscopic diagnosis is not available
• FBC: Anaemia, thrombocytopenia and leucopenia are common.
• FBC, electrolytes, glucose,
• LFTs, clotting screen and a CXR should be performed in all patients with acute falciparum malaria to assess severity
• U/E/Cr: raised creatinine, raised blood urea, looking for acute kidney injury AKI

Question 9

How should malaria be managed?

Answer 9

• Cases should be treated in hospital until parasitaemia has cleared.
• Non-falciparum malaria: chloroquine 600 mg stat, then 300 mg X 3 daily doses. Primaquine 15mg daily for 2 weeks to eliminate hepatic stage (check G6PD levels first).

• Falciparum malaria,

• mild: Artemisinin-based combination therapies preferred.
• Alternative choice is oral quinine 600 mg tds for 7 days, together with doxycycline 100 mg bd for 7 days.

Falciparum malaria, severe (as defined above): a medical emergency. Treatment is urgent and experience with severe malaria is essential.

• Intravenous (IV) artesunate plus clindamycin or doxycycline is treatment of choice for severe malaria.
• Intravenous quinine plus doxycycline is an alternative.
• Meticulous fluid management, regular monitoring of blood sugar and supportive therapy for organ dysfunction as required.
• Exchange transfusion may be considered for high parasitaemia with complications, but the indications and level of parasitaemia are controversial.

Question 10

What is the recommended chemoprophylaxis of malaria?

Answer 10

Mefloquine: 2

• 50mg (salt) per week, beginning 1 week before departure and continued for 4 weeks after leaving the endemic area.
• Advantage: weekly dosing, reasonable pricing.
• Disadvantage: neuropsychiatric side effects.

Doxycycline:

• 100mg daily beginning 1 to 2 days before entering the affected area and for 4 weeks after leaving the area.
• Advantage: cheap.
• Disadvantage: daily dosing.
• Side effects: photosensitivity, vaginal thrush and oesophagitis.

Atovaquone/proguanil (Malarone):

• 1 adult tablet once daily beginning 1 to 2 days before entering affected area and for 7 days after leaving the area.
• Advantage: few side effects, short duration of intake before and after travel.
• Disadvantage: expensive, daily intake.