Fig 2. Inferring transmission pathways of Plasmodium vivax genotypes within malaria clusters.

Circles represent individual study subjects carrying identical parasite genotypes; red and orange circles represent index and neighbor household (HH) members, respectively. Infections B1 and C, both diagnosed on day 0, have a common source (A) that had not been included in the study. D is a secondary infection with known source within the cluster (namely, B1). B2 and B3 have been diagnosed in the same subject as B1, 30 and 180 days later. If B1 was treated with chloroquine-primaquine (as all microscopy-positive infections were in our study), B2 may be either a recrudescence (due to chloroquine failure) or an early homologous relapse (due to primaquine failure to clear liver-stage hypnozoites); if B1 was missed by onsite microscopy and left untreated during our study, B2 may also represent a chronic, untreated blood-stage infection. B3 may represent either a chronic untreated infection (if B1 and B2 were left untreated) or a late homologous relapse (if chloroquine has successfully cleared blood-stage parasites but primaquine failed to clear hypnozoites).