For severe or acute malaria see the statewide Malaria Clinical Practice Guideline

Background

Malaria is caused by infection with protozoan parasites of the genus Plasmodium, transmitted by female mosquitos of the genus Anopheles. Four species cause nearly all infections in humans; P. falciparum, P. vivax, P. ovale and P. malariae. The microbiological and clinical features vary between species ( Table 1). The prevalence of malaria in African refugees arriving in Australia was between 5-15%^1-3 and as high as 25% in children from sub-Saharan Africa³ in the mid 2000s. This reduced with the introduction of pre-departure screening in 2005 (known as the Departure Health Check (DHC) since 2012). This is a voluntary health check for refugee entrants 3-7 days prior to departure for Australia. The DHC includes a rapid diagnostic test (RDT) for malaria and treatment if positive,⁴ however screening is voluntary, and uptake is incomplete. Recent arrivals from Afghanistan have not had a DHC. 

2016 ASID guidelines recommend malaria screening in people travelling from/through endemic areas (Bangladesh, Bhutan, Burma, India, Pakistan, Sri Lanka, African source countries. Note: not Egypt, Middle East).  In 2017-2018, clinicians noted presentations of African children with P. falciparum malaria in South Australia and Victoria. We have seen cases of P. vivax in arrivals from Afghanistan.

• People living in endemic areas develop anti-disease immunity followed by anti-parasite immunity. They may have asymptomatic infection, however they are at increased risk of symptomatic infection after migration as immunity wanes. 
• The highest burden of disease occurs in young children (<5 years) prior to the development of adequate immunity. This age group is at increased risk of rapid deterioration and death. 
• Severe malaria <is signs of vital organ dysfunction (including hypoglycaemia) or hyperparasitaemia (see below). Australian guidelines use a cut-off of parasitaemia >2%. In general, only P. falciparum causes severe disease. 
• Cerebral malaria <is defined as a patient with P. falciparum parasitaemia who does not respond to a painful stimulus and has no other identified cause of encephalopathy.⁵ 
• 98% of symptomatic P. falciparum infections present within 3 months post arrival.⁶ 
• 57% of symptomatic non falciparum infection present within 3 months post arrival and 96% within 12 months.⁶ 
• Infections can occur with multiple species, which will affect treatment. 
• Hypnozoites (dormant liver forms) only occur in P. vivax and P. ovale. These may cause a relapse of disease and require specific treatment. 

Assessment

History

• Countries of origin and transit, time since arrival 
• Previous malaria history and type if known 
• Recent screening and/or treatment (including prophylaxis)
  
• Current symptoms, including fever pattern (a classic fever paroxysm consists of 3 stages (in order) cold, hot, sweat, lasting 6-10 hours total, usually late in the day). Symptoms of malaria may be non-specific, such as fever, cough, headache, abdominal pain or vomiting
• Capacity to access health care in Australia (language skills, time since arrival, independent transport) 
• Others in family (who will also need screening).

Exam

• Assess conscious state, ​signs of respiratory distress, shock, neurological symptoms
  
• Other findings on examination may include pallor (due to anaemia), bruising (from thrombocytopenia) or jaundice. Splenomegaly is found in 25-40% of symptomatic cases. 

Screening

• Malaria should be excluded as a priority in all febrile recently arrived refugees from endemic areas (<3 months in Australia) with thick/thin film(s) and a RDT. Malaria may still be the cause of a febrile presentation in refugees settled for a longer period 
• All children aged <5 years from endemic areas, who have been in Australia <3 months should have malaria screening (thick/thin film and rapid diagnostic test) if not already performed, regardless of pre-departure screening/treatment OR the reason for presentation 
• All refugees from endemic areas in Australia <3 months should be screened for malaria as part of their outpatient assessment
• Refugees in Australia for longer than 3 months warrant screening if there is a history of recurrent febrile illnesses or a history of non-falciparum malaria. 

Investigations

Note: specify countries of origin and transit and recent treatment on pathology request forms.

Thick and thin films

• If the initial film is negative in patients suspected of having malaria, films should be repeated at 12-24 hour intervals. A fingerprick is adequate. Parasite counts are highest 4 hours after the fever has peaked 
• May not be sensitive if parasite counts are low (<20-50/mcl, possibly <100/mcl) 
• Are never reported as negative, only as no parasites identified 
• Thick films are used for diagnosis on malaria and parasite counts, thin films for morphology (species and stage) 
• P. knowlesi is indistinguishable from P. malariae on microscopy - P. malariae cases with a history of travel to South East Asia are treated as P. knowlesi - hence is it essential to document countries of origin/transit.
  

Rapid diagnostic tests

• Test sensitivity of the local RDT (ICT) is 84-97% (>90% for P. falciparum if parasite count >100/mcl) and specificity is 81-100% 
• The locally used RDT gives information on the presence of Plasmodium spp (by detecting parasite LDH) and whether the species is P. falciparum (by detecting HRPII) 
• RDT may remain positive for up to 4 weeks after successful parasite treatment (which is important to consider if people have been treated prior to arrival). 

Other tests in symptomatic patients

• FBE and film, platelet count, reticulocyte count 
• VBG, lactate, BSL 
• UEC and LFT 
• Coagulation 
• G6PD screen if quinine/primaquine will be used 
• Screen for pregnancy if indicated 
• Consider group and hold if transfusion may be required.

Management

• All patients with malaria should be managed in conjunction with an Infectious Diseases Specialist
• All patients with malaria require assessment in hospital. If there is any suggestion of symptoms (i.e. in a patient who has had outpatient refugee screening) the patient should be recalled to hospital immediately
• All patients will require a period of observation in hospital while treatment is commenced and/or admission
• Patients with severe malaria should be managed as for any severely unwell patient, including checking BSL and monitoring for anaemia and for seizure activity. Cardiac monitoring will be required for some medications (i.e. intravenous quinine)
• Family members should also be screened 
• Malaria is a notifiable disease.

Therapeutic guidelines for malaria are available (see RCH library drug information - intranet access required). Additional considerations include:

• Artemether-lumefantrine (Riamet) is PBS listed (to weight 5kg/age 3 months) for malaria (therefore health care card rates). Dosing/timing need clear explanation - and picture-based dosing aids may be useful. 
• Atovaquone-proguanil (Malarone) is a private script, and outpatient prescribing is usually not feasible because of cost considerations. 
• Chloroquine resistant Pl vivax occurs in Timor, Papua New Guinea and the Pacific region; other first line treatment options may be needed. 
• G6PD screening must be performed prior to prescribing primaquine. 

Outpatient management

Outpatient management may be considered if all the following criteria are met (adapted from⁷⁾

• Age >5 years 
• Clinically well 
• (Not pregnant) 
• Reviewed by a senior doctor and Infectious Diseases Unit consulted 
• No clinical or laboratory features of severe malaria 
• Has resided in endemic area for most of the previous year 
• Tolerated first dose of oral medication and observed 4-6 hours post 
• Family has sufficient understanding to ensure compliance and follow-up 
• Family has sufficient understanding and ability to return to hospital (by ambulance) if child becomes more unwell 
• Family have a discharge letter stating child has malaria (including type of malaria), with contact numbers and treatment details 
• No other co-morbidity requiring admission 

Even if all criteria are met, home-based nursing/Hospital in the Home should be considered for medication and clinical supervision. There are additional considerations in malaria-receptive areas in Northern Australia.

Follow-up

Patients should be seen in Infectious Diseases outpatients at 28 days with repeat thick/thin films and RDT, or immediately if symptoms recur.

Resources<

• <Malaria guidelines for Health Professionals in the Northern Territory (2012) 
• Malaria prevention and prophylaxis
  • CDC travel, CDC malaria, CDC malaria parasitology 
  • WHO malaria, WHO malaria country profiles 
  • Interactive malaria maps
• Picture-based dosing for artemether-lumefantrine.

Severe malaria: WHO definition [5]<

• Prostration 
• Impaired consciousness/coma 
• Respiratory distress (acidotic breathing) 
• Multiple convulsions 
• Circulatory shock 
• Pulmonary oedema or Acute Respiratory Distress Syndrome 
• Abnormal bleeding 
• Jaundice 
• Hemaglobinuria 
• Severe anaemia 
• Hypoglycaemia (<2.2 mmol/L) 
• Acidosis (HCO3 <15 mmol/L or base deficit >10 mmol/L) 
• High lactate (>5 mmol/L) 
• Hyperparasitaemia (>4% if non-immune child in area unstable endemicity, > 20% in stable endemic areas) 

Table 1: Malaria species

References

• References 

_{Immigrant health clinic resources. Author: Georgie Paxton, reviewed June 2020.}