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Malaria: A Complete Overview for PLAB 2

Updated: Jul 21

Malaria remains a critical tropical disease to understand, especially for doctors dealing with travel-related illnesses. Here's a concise yet detailed overview covering its presentation, fever patterns, diagnosis, treatment, and safety netting.



What is Malaria?

Malaria is a parasitic infection caused by Plasmodium species, transmitted through the bite of infected female Anopheles mosquitoes.


Common Plasmodium Species

  • P. falciparum – most severe, widespread in Africa and Asia.

  • P. vivax and P. ovale – cause relapsing malaria due to dormant liver stages.

  • P. malariae – quartan fever pattern.

  • P. knowlesi – zoonotic, daily fever pattern.



How Does Malaria Present?


General Symptoms

  • Fever (with or without a clear pattern)

  • Chills and rigors

  • Sweating

  • Headache

  • Malaise and fatigue

  • Muscle and joint pains

  • Nausea, vomiting, diarrhoea

  • Anaemia and jaundice in severe cases

  • Splenomegaly


Neurological Symptoms (Cerebral Malaria) (due to P. falciparum)

  • Confusion

  • Drowsiness

  • Seizures

  • Coma



Fever Patterns in Malaria


Classic Paroxysm (3 stages)

  1. Cold stage – chills and shivering

  2. Hot stage – high fever (39–41°C), headache, nausea

  3. Sweating stage – profuse sweating with temperature drop


Species-wise Patterns

  • P. vivax / P. ovale: Fever every 48 hours (tertian)

  • P. malariae: Fever every 72 hours (quartan)

  • P. knowlesi: Fever daily (quotidian)

  • P. falciparum: Often irregular or daily, due to asynchronous parasite cycles



Differential Diagnoses to Rule Out

When assessing a returning traveller with fever, consider:

Diagnosis

Key Symptoms to Ask

Dengue fever

Severe muscle pain, retro-orbital pain, rash, bleeding

Typhoid fever

Step-ladder fever, abdominal pain, constipation, headache

Viral hepatitis

Jaundice, dark urine, pale stools, RUQ pain

Influenza / Viral URTI

Sore throat, cough, runny nose, headache, myalgia

Leptospirosis

Headache, calf pain, jaundice, conjunctival suffusion, freshwater exposure

Scrub typhus (rickettsial)

Eschar, rash, lymphadenopathy, mite exposure

HIV seroconversion

Fever, sore throat, rash, lymphadenopathy, high-risk exposure

Traveller’s diarrhoea

Diarrhoea, vomiting, abdominal cramps

Amoebic liver abscess

RUQ pain, fever, history of amoebiasis

Schistosomiasis

Rash/itch at freshwater exposure site, urinary/abdominal symptoms

Investigations for Malaria

✅ Microscopy (thick and thin blood films)

  • Thick film: Detects presence of malaria parasites (high sensitivity)

  • Thin film: Identifies species by morphology (gold standard)

✅ Rapid Diagnostic Tests (RDTs)

  • Quick detection but limited species differentiation

✅ PCR

  • Highly sensitive; used in reference labs for species confirmation


Treatment of Malaria


If returning from Thailand (or Southeast Asia):

🔹 First-line for P. falciparum or unknown species

  • Artemether-lumefantrine (Riamet) – 6-dose regimen over 3 days

  • Atovaquone-proguanil (Malarone) – once daily for 3 days (alternative)

🔹 If P. vivax confirmed

  • Treat as above plus primaquine for radical cure (after G6PD testing) to eliminate liver hypnozoites.


Important Risk Factors Before Prescribing Antimalarials

✔️ G6PD deficiency (primaquine contraindicated)

✔️ Pregnancy status

✔️ Renal and hepatic function

✔️ Psychiatric history (mefloquine caution)

✔️ Cardiac history (QT prolongation risk)

✔️ Drug interactions

✔️ Regional resistance patterns


Public Health Notification and Isolation

✅ Notify Public Health England (or local health authority) – malaria is a notifiable disease.

✅ Isolation not required – malaria does not spread person-to-person, only via mosquitoes.

“We don’t need to isolate you because malaria doesn’t spread from person to person. It only spreads through mosquito bites.”

Admission Duration

  • Uncomplicated malaria: 1-2 days for treatment initiation and monitoring

  • Severe malaria: 3-7 days or longer, depending on organ involvement and response


Follow-up Advice and Safety Netting

✅ Complete full treatment course

✅ Attend follow-up appointments to confirm clearance

✅ Seek urgent medical help if:

  • Breathlessness or difficulty breathing

  • Severe weakness or confusion

  • Persistent vomiting

  • Severe abdominal pain

  • Yellowing of skin or eyes

  • Dark or very little urine

“Finish all your medicines even if you feel better. Come back for follow-up tests. If you feel very unwell, confused, very weak, or notice yellow skin or dark urine, go to the hospital immediately.”

Key Takeaway

Malaria is serious but treatable if identified early. Always take a detailed travel history, consider differentials, and start treatment urgently to prevent complications.


📚 References:

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