Malaria is a major cause of maternal and fetal morbidity and mortality across the world, especially in tropical and subtropical regions, and though not indigenous to the UK it may present in women who have recently returned from infected areas. Pregnant women are more susceptible to infection (especially if HIV-infected), and are more likely to suffer a recurrence and develop severe complications, with increased risk of death and fetal loss.
Malaria is caused by one of predominantly four Plasmodium species: P. falciparum, P. vivax, P. ovale and P. malariae. In the UK, malaria is more commonly associated with P. falciparum and less so with P. vivax. Infection with P. falciparum is more insidious and associated with a higher mortality than infection with the other species. In Asia, particularly India, infection with P. vivax is more likely, and this can cause a relapsing type of malaria.
The bite of the female Anopheles mosquito inoculates Plasmodium sporozoites that pass via the bloodstream to the liver and develop into schizonts. The schizonts rupture and release thousands of merozoites into the circulation, which accounts for the typical cyclical nature of symptoms. The merozoites enter red blood cells and once inside can multiply over 2-3 days and infect new red blood cells. In falciparum malaria, large numbers of parasites may be sequestered in the placenta, which may be the contributing factor to fetal loss.
Problems and special considerations
Women who are pregnant or planning to become pregnant should be advised not to travel to an endemic area unless necessary. Prevention advice is the same as for the non-pregnant population, though certain antimalarials are relatively contraindicated at certain stages of pregnancy and specialist advice is required.
A high index of suspicion is required, as presentation may be atypical. Clinical features usually develop within 1-3 weeks of infection and may include symptoms of anaemia or fever of unknown origin (which may be very variable or even absent). Splenomegaly may be present. Seizures or coma may be the only presenting symptom of cerebral malaria.
Thick and thin films for malarial parasites should be examined, but parasites may not be visible on peripheral blood films. Rapid diagnostic tests based on malaria antigens are less sensitive; polymerase chain reaction methods may be more accurate.
Haemolytic anaemia may be exacerbated by decreased iron and folate levels, leading to severe anaemia. Thrombocytopenia may occur; when this is associated with haemolysis, it produces a picture that may be confused with HELLP syndrome (see Chapter 85). Disseminated intravascular coagulation may occur in severe malaria. Hypoglycaemia is a common feature and may be aggravated by certain antimalarials. Severe complications such as pulmonary oedema, acute lung injury and cerebral malaria are associated with a high mortality rate.
Fetal mortality associated with malaria is in the region of 15% for P. vivax and 30% for P. falciparum. Problems for the fetus include prematurity, anaemia, fetal growth restriction and congenital malaria; the last of these may result from transfer of parasites across the placenta and is not always preventable by treatment of the mother. Affected neonates may feed poorly and be pyrexial, irritable or jaundiced (this may be confused with jaundice of the newborn), and may suffer long-term developmental problems such as short stature and metabolic disturbances.
Management options
Severe malaria in a pregnant woman is a medical emergency. The patient with a suspected or proven diagnosis should be managed in a tertiary centre where full facilities and input from specialists in infectious diseases are available. Early admission to the intensive care unit is recommended for all but the mildest disease. Quinine and clindamycin are the standard drugs used for uncomplicated falciparum malaria, and chloroquine for the other types; intravenous artesunate or quinine is recommended for severe falciparum malaria (see RCOG guidelines for dosage). Close fetal and maternal monitoring is required, and expedited delivery of a late preterm fetus may be necessary. Management of severe complications is largely supportive.
Regional and general anaesthetic techniques have been described in mothers with malaria. If general anaesthesia is used, there are particular considerations: quinine therapy can prolong neuromuscular blockade and the hypoglycaemia induced by its use may be masked under general anaesthesia. Regional anaesthesia may be considered if there is no evidence of cerebral involvement and in the absence of secondary bacterial sepsis.
Key points
• Pregnant women are more susceptible to malaria because of their decreased immunity.
• Malaria may present with atypical symptoms, and mortality is high for both fetus and mother.
• Senior staff should be involved in obstetric and anaesthetic management, and advice should be sought from clinicians experienced in the management of malaria.
• The choice of anaesthetic technique should be based on each individual situation.
Further reading
Lalloo DG, Shingadia D, Bell DJ, et al.; PHE Advisory Committee on Malaria Prevention in UK Travellers. UK malaria treatment guidelines. J Infect 2016; 72: 635-49.
Mathew DC, Loveridge R, Solomon AW. Anaesthetic management of caesarean delivery in a parturient with malaria. Int J Obstet Anesth 2011; 20: 341-4.
Royal College of Obstetricians and Gynaecologists. Malaria in Pregnancy: Prevention. Green-top Guideline 54A. London: RCOG, 2010 (updated 2017). www.rcog.org.uk/en/guidelines-research- services/guidelines/gtg54a (accessed December 2018).
Royal College of Obstetricians and Gynaecologists. Malaria in Pregnancy: Diagnosis and Treatment. Green-top Guideline 54B. London: RCOG, 2010 (updated 2017). www.rcog.org.uk/en/guidelines- research-services/guidelines/gtg54b (accessed December 2018).
Soltanifar D, Carvalho B, Sultan P. Perioperative considerations of the patient with malaria. Can J Anesth 2015; 62: 304-18.
Tarning J. Treatment of malaria in pregnancy. N Engl J Med 2016; 374: 981-2.