Figure 2.

Effect of Plasmodium falciparum infection on levels of specific human volatile compounds. Compounds of interest identified in samples of (a) CHMI1 and (b) CHMI2 were analysed by temporal parasitological status [Before: sampling timepoint before malaria challenge; During: 6–8 days post malaria challenge, with (−) and (+) referring to parasitological status, measured by qPCR; After: after antimalarial treatment; Control: headspace collected from empty control bags]. Back-transformed predicted means (REML) are shown (amounts in ng collected over 100 min. for Porapak – left two panels, amounts in peak area units*1000 collected over 20 min for Tenax – right three panels). For predicted means (log transformation) with standard errors, see Supplementary Fig. S4 and Tables S1 and S2 for pairwise SEDs. In CHMI2, the number of Porapak and Tenax samples varied as indicated in the figure legend; exact n given in Table 2, and Fig. S4. RI 1095 (CHMI1) and 1-Dodecene, dodecanal, methyl dodecanoate and RI 1416 (CHMI2) each co-eluted with another unidentified compound and hence their quantities are difficult to obtain accurately. Differences in amounts observed in temporal P. falciparum infection categories can therefore not be attributed with absolute certainty to these compounds.