Screening strategies and laboratory assays to support Plasmodium falciparum histidine-rich protein deletion surveillance: where we are and what is needed

Table 3 Different scenarios affecting the estimates for true pfhrp2/3 deletion prevalence

Scenario	Implications for antigen detection	Implications for DNA detection	Implications for prevalence estimates and clinical impact	References
Multiclonal infection with wild-type and deleted P. falciparum	Deleted parasites not detected even though antigen is detected	Deleted parasites not detected by conventional PCR, though possible to detect using multiplex real-time or dPCR	Underestimate true gene deletion prevalence, though no clinical impact or effect on false-negative RDT prevalence	[24, 37, 38]
Residual HRP2 from previous P. falciparum infection, and current infection with deleted P. falciparum	Positive result regardless of current P. falciparum infection status	No effect	Underestimate true gene deletion prevalence due to phenotypic positivity. No clinical impact	[59, 60]
Low-level and spatial heterogeneity of deletions	Results not representative	Results not representative	Incomplete data available to guide decision making	[61]
Seasonal fluctuations in deletion prevalence	Results not representative	Results not representative	Incomplete data available to guide decision making	[25]

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