Malaria

Malaria is an infectious disease caused by members of the Plasmodium family of protozoan parasites. Protozoa are single celled organisms.

The most severe and dangerous member of the family is Plasmodium falciparum. This accounts for about 75% of the cases of malaria in the UK.

Malaria is spread through bites from the female Anopheles mosquitoes that carry the disease. It commonly occurs in travellers to areas where malaria is known to be present.

Types

  • Plasmodium falciparum is the most severe and dangerous form
  • Plasmodium vivax
  • Plasmodium ovale
  • Plasmodium malariae

 

Life Cycle

Malaria is spread by female Anopheles mosquitoes, most commonly at night time. Infected blood is sucked up by feeding mosquito. The malaria in the blood reproduces in the gut of the mosquito producing thousands of sporozoites (malaria spores).

When that mosquito bites another human or animal the sporozoites are injected by the mosquito. These sporozoites travel to the liver of the newly infected person. They can lie dormant as hypnozoites for several years in P. vivax and P. ovale.

They mature in the liver into merozoites which enter the blood and infect red blood cells. In red blood cells the merozoites reproduce over 48 hours, after which the red blood cells rupture releasing loads more merozoites into the blood and causing a haemolytic anaemia. This is why people infected with malaria have high fever spikes every 48 hours.

 

Presentation

Suspected malaria in someone who lives or has travelled to an area of malaria. The incubation period is 1-4 weeks after infection with malaria although it can lie dormant for years.

 

Non-specific Symptoms

  • Fever, sweats and rigors
  • Malaise
  • Myalgia
  • Headache
  • Vomiting

 

Signs

  • Pallor due to the anaemia
  • Hepatosplenomegaly
  • Jaundice as bilirubin is released during the rupture of red blood cells

 

Diagnosis

A diagnosis can be made using a malaria blood film. This is sent in an EDTA bottle (the red top bottle used for a FBC). Examining the malaria blood film will show the parasites, the concentration and also what type they are.

3 samples are sent over 3 consecutive days to exclude malaria. This is due to the 48 hour cycle of malaria being released into the blood from red blood cells. The sample may be negative on days where the parasite is not released but becomes positive a day or two later when they are released from the RBCs.

 

Management

Discuss patients with the local infectious diseases unit for advice on management. All patients with falciparum malaria should be admitted for treatment as they can deteriorate quite quickly.

Oral options in uncomplicated malaria:

  1. Artemether with lumefantrine (Riamet)
  2. Proguanil and atovaquone (Malarone)
  3. Quinine sulphate
  4. Doxycycline

 

Intravenous options in severe or complicated malaria:

  1. Artesunate. This is the most effective treatment but is not licensed.
  2. Quinine dihydrochloride

 

TOM TIP: Remember artesunate and quinine as treatment options for your exams as these are the most likely to be relevant. Remember that Plasmodium falciparum is the most common and severe cause and these patients should be admitted for artesunate treatment and monitoring for complications.

 

Falciparum Complications

Plasmodium falciparum is the most severe form and has multiple complications. Patients should be carefully monitored for complications and treated appropriately. There is a long list of complications:

  • Cerebral malaria
  • Seizures
  • Reduced consciousness
  • Acute kidney injury
  • Pulmonary oedema
  • Disseminated intravascular coagulopathy (DIC)
  • Severe haemolytic anaemia
  • Multi-organ failure and death

 

Malaria Prophylaxis

General advice:

  • Be aware of locations that are high risk
  • No method is 100% effective alone
  • Use mosquito spray (e.g. 50% DEET spray) in mosquito exposed areas
  • Use mosquito nets and barriers in sleeping areas
  • Seek medical advice if symptoms develop
  • Take antimalarial medication as recommended

 

Antimalarials

Antimalarial medications are around 90% effective at preventing infections. There are several options.

 

Proguanil and atovaquone (Malarone)

  • Taken daily 2 days before, during and 1 week after being in endemic area
  • Most expensive (around £1 per tablet)
  • Best side effect profile

 

Mefloquine

  • Taken once weekly 2 weeks before, during and 4 weeks after being in endemic area
  • Can cause bad dreams and rarely psychotic disorders or seizures

 

Doxycycline

  • Taken daily 2 days before, during and 4 weeks after being in endemic area
  • Broad-spectrum antibiotic therefore it causes side effects like diarrhoea and thrush
  • Makes patients sensitive to the sun causing a rash and sunburn

 

Last updated April 2019
WordPress Theme built by Shufflehound. Copyright 2016-2020 - Zero to Finals - All Rights Reserved