Malaria

Background information

Testing

Treatment

Prevention

Patient information (English only)

Patient information (English and other languages)

Other useful resources

References

Background information

• Approximately half of the global population, many of whom live in the world's poorest countries, are at risk of malaria and over 200 million people are infected annually [2].  
• Malaria is very common; in parts of Africa the average person will have malaria several times a year.
• In the UK, between 1,500 and 2,000 people are diagnosed with malaria each year, having acquired it abroad.  
• During 2005-2009, 73% of cases diagnosed in the UK were born in Africa or South Asia [3].
• Malaria is a febrile illness due to infection of red blood cells with the Plasmodium parasite.
• The parasite is transmitted through the bite of an Anopheles mosquito after dark [1,4].
• Malaria transmission rates are affected by local factors such as rainfall patterns, proximity of mosquito breeding sites, mosquito species and time of day. Some regions have a fairly constant number of cases throughout the year, whereas in other regions transmission varies in intensity throughout the year and highest rates usually coincide with the rainy season [2].
• There are 4 main types of malaria that affect humans: 
  • Plasmodium falciparum: causes most malaria deaths world wide and accounts for three quarters of all cases in the UK [1,4,5].
  • Plasmodium vivax: less serious but can cause a relapsing malaria; accounts for 15%.of cases in the UK [1,5]. 
  • Plasmodium ovale: less common, may also cause a relapsing disease [1].
  • Plasmodium malariae: the least common benign form seen in the UK, patients may present many years after infection [1].
• The minimum incubation period for naturally acquired infection is 6 days, but is more usually 13 to 28 days, so that most patients with P. falciparum present within a month of exposure and almost all present within 6 months of exposure [5]. Other forms of malaria may present a year or more after return from a malarious area.
• Malaria should be considered in anyone with a fever, or history of a fever, who has recently returned from or previously visited a malaria endemic area in the last year, regardless of whether they have taken prophylaxis. The temperature may be normal at the time of presentation [5].
• Clinical presentations of malaria can vary, but features may include [1]:
  • Fever/sweats/chills
  • Malaise
  • Myalgia
  • Headache
  • Diarrhoea
  • Cough
• Symptoms of severe or complicated falciparum malaria in adults:
  • Renal impairment
  • Acidosis
  • Hypoglycaemia
  • Pulmonary oedema or acute respiratory distress syndrome (ARDS)
  • Low haemoglobin 
  • Spontaneous bleeding/disseminated intravascular coagulation
  • Shock 
  • Haemoglobinuria (without G6PD deficiency)
• Symptoms of severe or complicated malaria in children:
  • Impaired consciousness or seizures
  • Respiratory distress or acidosis 
  • Hypoglycaemia
  • Severe anaemia
  • Prostration 
  • Hyperparasitaemia 
• Particular care must be taken in pregnant women from endemic countries, who may have malaria without typical symptoms. Anaemia should raise suspicion of malaria in this group.

For further background information please see the HPA malaria pages.

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Testing

Suspected malaria is a medical emergency. Initial assessment and treatment guidelines are available from the British Infection Association [external link]

Sample required for diagnosis: An EDTA-anti-coagulated venous blood sample.

Diagnosis of malaria by microscopic examination of thick and thin blood films will be performed by your haematology or microbiology department depending on local arrangements.

Blood tests 

• A blood sample should be taken and received in the laboratory within one hour; there is no need to wait for fever spikes before taking blood.
• All laboratories making a diagnosis of malaria should send blood films and a portion of the blood sample on which the diagnosis was made to the HPA Malaria Reference Laboratory (MRL) for confirmation.  
• Always include the travel history in the information provided on the test request form. 

Blood film negative malaria

• One negative blood film does not exclude a diagnosis of malaria. Where malaria is suspected blood films should be examined daily for 3 days whilst other diagnoses are also considered. 
• If all three films are negative and malaria is still considered a possible diagnosis, expert advice should be sought from a specialist in tropical or infectious diseases. 
• It is particularly important to seek expert advice early in the care of pregnant patients with suspected malaria since the parasite may be sequestered in the placenta resulting in negative peripheral blood films despite the patient having malaria [1].

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Treatment

In the UK malaria treatment is mainly undertaken by secondary care infectious disease specialists. The role of the primary care practitioner is to be vigilant for possible cases by always asking about travel history in patients with a fever (see fever algorithm), and to ensure prompt testing and referral.

For further information please see the UK malaria treatment guidelines [external link].

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Prevention

Malaria should be almost completely preventable if appropriate anti-mosquito and chemoprophylactic measures are taken. The primary care practitioner has a vital role to play in ensuring that those at risk of acquiring malaria receive adequate information about how to protect themselves and in prescribing anti-malarials as appropriate. Country by country advice on malaria prevention is available from the National Travel Health Network and Centre [external link] (NaTHNaC).

For further information please see the HPA Advisory Committee on Malaria Prevention Guidelines.

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Patient information (English only)

NaTHNaC malaria leaflet for travellers [external link]

NaTHNaC malaria prophylaxis leaflet for travellers [external link]

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Patient information (English and other languages)

HPA malaria leaflet (English version)

Malaria leaflet in Bengali (PDF, 314 KB) 

Malaria leaflet in Gujarati (PDF, 369 KB) 

Malaria leaflet in Punjabi (PDF, 146 KB) 

Malaria leaflet in Urdu (PDF, 360 KB)

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Other useful resources

The Hospital for Tropical Diseases [external link] dedicated to the prevention, diagnosis and treatment of tropical diseases and travel related infections.

Liverpool School of Tropical Medicine [external link] this institution and the associated Tropical and Infectious Disease Unit in the Royal Liverpool University Hospital provide advice on prevention, diagnosis and management of tropical infections. 

WHO malaria page [external link] general information on malaria

NaTHNaC frequently asked questions on malaria prevention for health professionals [external link]

NaTHNaC malaria information for health professionals [external link]

Royal College of Obstetricians and Gynaecologists: The prevention of malaria in pregnancy [external link]

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References

1. Chiodini P L, Hill D, Laloo D, Lea G, Walker W, Whitty C J, Bannister B. Guidelines for malaria prevention in travellers from the United Kingdom. London: Health Protection Agency, 2007. 
2. World Health Organization. Malaria page [external link]
3. Health Protection Agency. Malaria data 
4. Health Protection Agency. Malaria page  
5. Laloo D G, Shingadia D, Pasvol G, Chidoni P L, Whitty C J, Beeching N J, Hill D R, Warrell D A, Bannister B A. UK malaria treatment guidelines [external link]. Journal of Infection 2007; 54: 111-121.

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