HRP-2 deletion makes diagnostics further imperfect for low malaria transmission context in the Amazon Region Jaime Chang, USAID 1 April 2014 Following on the 2010 report by Gamboa et al. on a large proportion of Plasmodium falciparum isolates from the Peruvian Amazon lacking HRP-2 and HRP-3 (DOI: 10.1371/journal.pone.0008091), colleagues from CDC and Amazon countries have assessed the frequency of deletion of HRP-2 and HRP-3 genes among P. falciparum strains circulating in Bolivia, Brazil, Colombia, Guyana, Peru, and Suriname. The deletions were found in parasites from all countries but Guyana. In the other countries HRP-2 deletion frequencies ranged between 4% and 33%, while HRP-3 deletion frequencies ranged between 3% and 53%. By adding a shortcoming to HRP-2 dependent rapid tests, this further complicates efforts against malaria in a region with decreasing malaria transmission, where most remaining malaria occurs in difficult to reach populations where microscopy diagnosis is not easily available. Manuscripts reporting these findings are in preparation. The assessment was a collaborative effort involving scientists from CDC and the six amazon countries listed above, done as part of activities supported by USAID’s Amazon Malaria Initiative (www.usaidami.org) Competing interests None.