1 Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; Tropical and Infectious Disease Unit, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK. Electronic address: sandrogerada@gmail.com.
2 Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; Tropical and Infectious Disease Unit, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK. Electronic address: nickbeeching@gmail.com.