Malaria is a serious, potentially fatal, but preventable, febrile illness caused by the parasite Plasmodium, transmitted to humans by the bite of a female Anopheles mosquito, most active between dusk and dawn. Red blood cells are infected with the parasite Plasmodium. Five species of Plasmodium can infect humans (Table 1). Malaria is distributed throughout the tropics. In Africa, P. falciparum causes most severe malaria cases and deaths. P. vivax mostly dominates in countries outside of sub-Saharan Africa. P. knowlesi is usually transmitted from monkeys to humans by mosquito bites in South-East Asia (UK Health Security Agency (UKHSA), 2022a). A pictorial illustration of the malaria life cycle indicating where preventative measures act, is included in the malaria guidelines (UKHSA, 2022a). Insect bite avoidance is crucial to prevent bites from infected mosquitoes causing infection. Causal prophylaxis acts on the parasite in the liver, whereas suppressive prophylaxis acts on parasites in the red blood cells (UKHSA, 2022a).
Table 1. Plasmodium species that infect humans
| Species | Comment | Number of cases reported in the UK in 2019 out of 1719 |
|---|---|---|
| Plasmodium falciparum | The most dangerous, responsible for the majority of malaria deaths worldwide | 1475 (85.8%) |
| Plasmodium vivax | A relapsing malaria | 72 (4.2%) |
| Plasmodium ovale | A relapsing malaria | 114 (6.6%) |
| Plasmodium malariae | May present with late recrudescence after many years | 43 (2.5%) |
| Plasmodium knowlesi | Very rarely imported at present, but capable of producing severe illness | 1 (<0.1%) |
Travellers' risk
Endemicity and transmission patterns vary. Despite disruptions to prevention, diagnosis and treatment during the pandemic, countries largely averted further setbacks to malaria control with only moderate levels of disruption reported (World Health Organization, 2022). Travel health practitioners should always refer to individual country recommendations for current guidance. For selected countries, the malaria guidelines provide printable in-country maps of prophylactic advice linked to malaria distribution. Maps are subject to change so travel health practitioners should always refer to current information (UKHSA, 2022a; NaTHNaC, undated). All travellers visiting malaria endemic areas are at risk of exposure. Due to an increased risk of developing severe malaria and a higher fatality risk, pregnant travellers should avoid travel to malaria endemic areas. They must be made aware of the risks of the disease and the risks and benefits of antimalarial chemoprophylaxis, particularly if travel is unavoidable. UK migrants born in malaria endemic areas who return there to visit friends and family (VFRs) may be at higher risk (UKHSA, 2023a). These travellers may not seek, or feel they don't need, pre-travel advice on malaria preventive measures, believing they have immunity. With no risk of malaria in the UK, any immunity they did have wanes quickly on migration. Children born in the UK will have no immunity. All visitors to malaria endemic areas, particularly VFRs and those at higher risk of exposure, should follow the ABCD of malaria prevention and be aware of the importance of employing all recommended preventive measures (Table 2). In the UK, VFRs to West Africa account for the highest number of imported malaria cases annually. Most cases were caused by P. falciparum (Public Health England (PHE), 2019; 2021).
Table 2. The A B C D of malaria prevention
| A | Awareness of the risk |
| B | Bite prevention |
| C | Chemoprophylaxis (appropriate medication and compliance) |
| D | Diagnosis (prompt medical care and treatment) |
As international travel was restricted during the pandemic, imported cases of P. falciparum malaria subsequently fell, but have since increased. Data predicts that the total for 2022 may exceed the 2019 figure of 1475 cases (PHE, 2021; UKHSA, 2022c).
Pre-travel risk assessment
Conducting a pre-travel risk assessment and providing appropriate advice to the individual is essential. Healthcare professionals should be competent in the process (Royal College of Nursing (RCN), 2018). Undertaking a comprehensive pre-travel risk assessment and communicating the risk of malaria at the destination, the importance of insect bite prevention and other preventive measures, takes time and should be clearly communicated (UKHSA, 2022a). A traveller may present with complex health issues or pre-conceived notions of their risk of malaria exposure, which needs time to explore and discuss. For example, some travels may be taking medications that are incompatible with antimalarial drugs. Sufficient time should be allotted to assess individual risk and deliver appropriate management advice correctly. Communication skills are key to an effective consultation and should be supported by a range of methods and tools (Chiodini et al, 2020). Reasonable steps must be taken to meet language and communication needs (Nursing and Midwifery Council, 2018), including an accredited interpreter if necessary (RCN, 2020). Nurses should obtain a full medical history, including current prescribed medication, pre-existing health issues and drug allergies (UKHSA, 2022a). A risk assessment template for those advising on malaria prevention is provided in the malaria guidelines (UKHSA, 2022a). When an antimalarial is prescribed, including an over-the-counter pharmacy-only medicine, a risk assessment should be undertaken (UKHSA, 2022a). For those providing travel health services in England and regulated by the Care Quality Commission (CQC), the CQC confirms that the provision of travel health services includes pre-travel risk assessment and travel health advice including malaria prevention (CQC, 2022).
Prevention
Malaria is preventable. It is important that advisors have an understanding of the malaria life cycle. Nurses should emphasise the ABCD of malaria prevention (Table 2) and provide supporting information, through websites and leaflets, which are available in various languages (PHE, 2010). The malaria prevention guidance emphasises that effective bite prevention should be the first line of defence against malaria infection (UKHSA, 2022a; NaTHNaC, 2023). For some destinations, ACMP advises awareness of risk and bite prevention without recommending chemoprophylaxis. However, where chemoprophylaxis is recommended, the benefits of employing bite prevention measures should still be emphasised, as they are effective against malaria and other vector-borne diseases. Bite prevention measures include insect repellents, wearing long sleeved tops, trousers and socks if outdoors after sunset and using insecticide-treated bed nets (UKHSA, 2022a).
As P. falciparum malaria can progress quickly to a severe, life-threatening illness, prompt diagnosis and treatment are paramount. Travellers should be made aware of the signs and symptoms of malaria, and advised to seek prompt medical attention, while abroad or for up to a year after return, stating their travel itinerary and destination (UKHSA, 2022a).
Chemoprophylaxis
Recommendations for antimalarials should be appropriate for the destination, tailored to the individual, and account for the risks and benefits to the traveller. No regimen is 100% effective, but combined malaria preventive measures offer the best protection. Travellers should source chemoprophylaxis medication from a reputable UK source before departure and be advised that antimalarials purchased abroad or online could be fake. Prophylactic regimens against malaria for adults and children and those in higher risk categories, for example pregnant women, advice should follow the UKHSA (2022a) guidance. Although aimed at healthcare workers and developed specifically for travellers from the UK, it is open for public access and for travellers wishing to explore their options (UKHSA, 2022a). For most travellers, standby emergency antimalarial medication is not routinely recommended. Emergency standby treatment is recommended for those taking chemoprophylaxis and visiting remote areas where they are unlikely to be within 24 hours of medical attention. Standby treatment should be started if it is impossible to consult a doctor and/or reach a diagnosis within 24 hours of the onset of fever. A traveller information leaflet can be copied for use when required (UKHSA, 2022a).
Box 1.Key points from Guidelines for malaria prevention in travellers from the UK
- COVID-19 likely affected malaria eradication programmes in endemic areas
- COVID-19 affected international travel reducing the number of malaria cases imported into the UK
- Case numbers are increasing. The Malaria Reference Laboratory (MRL) and Hospital for Tropical Diseases (HTD) are concerned about increased severity and/or higher parasitaemia in falciparum malaria cases
- Risk of misdiagnosis in imported malaria cases. Non-specific clinical features may be mistaken for COVID-19, influenza, or another infectious disease, leading to delayed treatment. Death due to misdiagnosis of imported falciparum malaria has occurred in the UK.
- Ensuring protection against malaria for those potentially risking exposure and maintaining awareness of malaria as a possible diagnosis in returned travellers is greater than ever.
- ACMP will keep its advice for travellers to individual countries under review. Check regularly for updates and changes to recommendations.
- The World Health Organization (WHO) World Malaria Report 2020 indicates moderate levels of disruption in many countries.
- It is possible that due to increased transmission, travellers' risk of malaria infection increases for some areas, with possible re-introduction to areas recently considered to have interrupted transmission. Stay alert to changes and temporary recommendations.
- Updated section on insect bite avoidance to emphasise it as the first line of defence in preventing malaria and the importance of malaria prevention measures.
- Travel providers in England regulated by the Care Quality Commission (CQC) should include pre-travel risk assessments, travel health advice, including malaria prevention measures.
- Includes detailed advice for special risk groups, including pregnant travellers or those planning a pregnancy.
- FAQ section.
- References can be linked directly from the document.
- Healthcare professionals working in England, Wales or Northern Ireland are advised to use the ACMP guidelines as their preferred source of guidance for malaria prevention.
UKHSA, 2022a
The disease
The incubation period of P. falciparum malaria is 7–14 days, but can be longer where there is partial immunity or if antimalarials have suppressed the parasite. In P. vivax or P. ovale infection incubation is 12–18 days, but can be months or years (rarely) due to emergence of latent hypnozoites from the liver entering the bloodstream. (NaTHNaC, 2021). If treatment is delayed in those infected with P. falciparum, illness can progress rapidly and lead to serious life-threatening complications. Travellers should be aware of the signs and symptoms of malaria, which presents with non-specific symptoms like fever, sweating or chills, malaise, myalgia, headache, diarrhoea or cough. Malaria cannot be excluded or confirmed by clinical features alone. Absence of fever does not exclude malaria, while malaria with fever may be misdiagnosed or confused with another illness (UKHSA, 2022a). Malaria is a notifiable disease (UKHSA, 2022b).
Diagnosis and treatment
Practitioners should be alert to travellers returning from a malaria risk area presenting with fever or flu-like symptoms and consider a malaria diagnosis (UKHSA, 2022a). Such travellers should be investigated urgently. Treatment should be initiated in consultation with an infectious disease or tropical medicine unit and according to the ACMP malaria treatment guidelines (Lalloo et al, 2016; NaTHNaC, 2021). The first case of P. falciparum artemisinin drug resistant malaria was reported in a UK resident who travelled to Uganda. Artemisinin is the most important therapeutic agent for malaria, especially malaria resistant to other drugs. This highlights the importance of malaria prevention measures and compliance with antimalarial chemoprophylaxis. Current preventive measures are over 90% effective when used correctly (UKHSA, 2023b). Where illness occurs abroad, travellers should know to seek medical help immediately. During remote travel, rapid diagnostic tests (RDTs) are available for diagnosis but not recommended for routine use (UKHSA, 2022a).
Summary
The UKHSA Advisory Committee on Malaria Prevention (ACMP) publishes practical updated malaria prevention guidelines for travellers from the UK annually. This is a key resource for healthcare professionals advising travellers. As temporary recommendations may occasionally be necessary, practitioners must ensure that current advice is sourced. Malaria is a mosquito-borne, potentially fatal disease. A comprehensive pre-travel risk assessment is essential for gathering information, including a full medical history. Travellers from the UK visiting malaria endemic areas should know that malaria is preventable and be advised on the ABCD measures necessary for protection. As no malaria regimen is 100% effective, nurses should emphasise the importance of insect bite avoidance and other malaria preventative measures. As malaria presents with non-specific symptoms, there is concern that imported cases may be wrongly diagnosed as another infectious illness, resulting in delayed treatment and severe or fatal consequences. In ill travellers returning from malaria risk areas, think malaria first, or until it is excluded from the diagnosis.
KEY POINTS:
- Malaria is a mosquito-borne, potentially fatal disease
- Conducting a pre-travel risk assessment and providing appropriate advice to the individual is essential
- Travellers from the UK visiting malaria endemic areas should know that malaria is preventable and be advised on the ABCD measures necessary for protection
CPD REFLECTIVE PRACTICE:
- How could you encourage those who are visiting friends and relatives to seek advice on malaria prevention?
- How would you advise a pregnant woman who wanted to travel to a malaria endemic region?
- What preventive advice would you give to travellers?