Plasmodium vivax and ovale infections both follow chronically relapsing courses, leading to
cumulative morbidity and mortality. P. vivax is the second most common malaria worldwide,
with an estimated 13.8 million cases annually, and there is increasing concern about severe
illness and death in vulnerable populations.
Radical cure of P.vivax and P.ovale with 8-aminoquinolines is necessary to prevent relapse.
The most widely 8-aminoquinoline is primaquine (7-14 day course), which has been used for
almost 75 years. Its widespread use is hampered by the potentially severe haemolysis
primaquine may trigger in individuals with glucose-6-phosphate dehydrogenase (G6PD)
deficiency, the most common red blood cell enzyme deficiency in the world. Safe
administration of primaquine requires at least 30% of normal G6PD activity to avoid
significant hemolysis.
Screening for malaria is routine in pregnancy, leading to improved detection of P. vivax
infections, but primaquine and is contraindicated in pregnancy. As a result, relapses of P.
vivax are common in postpartum and lactating women. Normal G6PD activity levels in infants
less than 6 months old have only recently been described and have only been established along
the Thailand-Myanmar border. Most low-resource settings are therefore unable to determine
infant G6PD status. Uncertainty about infant G6PD status means that breastfeeding women are
rarely offered radical cure because of theoretical concerns about drug exposure through
breast milk triggering haemolysis in breastfed infants and children with G6PD deficiency.
Though neonates generally have higher G6PD activity than adults, increased haemolysis for a
neonate could theoretically contribute to neonatal jaundice and anaemia.
Understanding drug exposure to a breastfeeding neonate is operationally important, as
interventions that can be safely offered before women leave the hospital postpartum have
higher uptake. Current World Health Organization guidelines advise against prescribing
primaquine to lactating women if they are breastfeeding infants less than 6 months old, or
breastfeeding infants with G6PD deficiency or unknown G6PD status.