# Parasitological efficacy of seasonal malaria chemoprevention in Nampula, northern Mozambique

## TL;DR

This study evaluated the effectiveness of seasonal malaria chemoprevention in Mozambique and found that amodiaquine was less effective, while other drugs had limited impact.

## Contribution

The study provides new insights into the parasitological efficacy of SMC drugs in a high malaria transmission setting.

## Key findings

- Parasitaemia prevalence decreased from 68% to 41% after SMC administration.
- Preventive efficacy was 97% for Plasmodium ovale and 42% for Plasmodium falciparum.
- One-third of P. falciparum infections had gametocytaemia, indicating potential for transmission.

## Abstract

Deployment of seasonal malaria chemoprevention (SMC) for young children using monthly sulphadoxine-pyrimethamine-amodiaquine (SPAQ) has recently been extended to Central and East Africa.

A pilot pharmacometric assessment was nested within a larger deployment of SMC in a high malaria transmission area in northern Mozambique. SPAQ was given to 460 healthy children in two large villages. Simultaneous filter-paper blood spot malaria quantitative PCRs, blood slide microscopy and antimalarial drug measurements were taken before, then 7 and 28 d after first SPAQ administration.

After SPAQ, parasitaemia prevalence decreased from 68% to 41%. Among children followed successfully for 28 d, malaria parasitaemia prevalence declined from 71% to 44%. Preventive efficacy was 97% for Plasmodium ovale and 42% for Plasmodium falciparum. Reinfections (N=50 with sufficient DNA for genotyping) and recrudescences (N=3) often grew through high concentrations of desethylamodiaquine, yet all 250 P. falciparum isolates genotyped were Pfcrt 76K, a molecular marker of 4-aminoquinoline susceptibility. One-third (21/64) of microscopy-detectable breakthrough P. falciparum infections had patent gametocytaemia. There was a clear chemoprevention exposure–response relationship evident for desethylamodiaquine, but not for sulphadoxine or pyrimethamine.

In Nampula, northern Mozambique, amodiaquine had low parasitological efficacy and sulphadoxine and pyrimethamine did not contribute significantly to chemoprevention.