Contents lists available at ScienceDirect Infection, Genetics and Evolution journal homepage: www.elsevier.com/locate/meegid Short communication Identification of Plasmodium falciparum isolates lacking histidine-rich protein 2 and 3 in Eritrea Michela Menegon a,⁎ , Mariangela L'Episcopia a , Abduselam M. Nurahmed b , Albadawi A. Talha c , Bakri Y.M. Nour d , Carlo Severini a a Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità (ISS), Rome, Italy b Cansford Laboratories, Pentwyn Business Centre, Cardiff, UK c Faculty of Medical Laboratory Sciences, University of Gezira, Wad Medani, Sudan d Blue Nile Research National Institute for Communicable Diseases University of Gezira, Wad Medani, Sudan ARTICLE INFO Keywords: Malaria Plasmodium falciparum Antigens Histidine-rich protein 2 Histidine-rich protein 3 Eritrea ABSTRACT The histidine-rich protein 2 of Plasmodium falciparum is the most common malaria antigen targeted by rapid diagnostic tests for the specific diagnosis of P. falciparum. Recently, pfhrp2 gene deletions have been documented in P. falciparum isolates from South America and some multiple endemic countries in Africa and Asia. Parasites with such gene deletions can produce false negative diagnostic results using HRP2-based rapid diagnostic kits. In the present work, the prevalence of P. falciparum parasites lacking pfhrp2, pfhrp3, which produces a second P. falciparum antigen that is recognized by PfHRP2 -based rapid diagnostic tests, and their flanking genes was evaluated in 135 P. falciparum isolates from Gash Barka region and in 9 isolates from Debub region, in Eritrea. In the analyzed samples, 56% (81/144) of isolates were pfhrp2/pfhrp3 positive, while 9.7% (14/144) showed de- letion of exon 2 of pfhrp2 gene and 43% (62/144) of isolates lacked the pfhrp3 gene. These results suggest that the pfhrp2 and pfhrp3 deletion phenomenon is present in a considerable proportion in the study areas, thus making the HRP2/3 based rapid diagnostic tests not completely reliable for malaria diagnosis in Eritrea. 1. Introduction Malaria is a public health challenge world-wide, with an estimated 3.2 billion people at risk for infection in 95 countries. Notwithstanding there has been a 48% reduction in malaria mortality rates globally since 2000. The World Health Organization (WHO) estimates that 214 mil- lion cases occurred in 2015 which led to approximately 438,000 deaths (WHO, 2015). Despite Eritrea being one of the least developed countries in the world, according to the (World Bank/Eritrea, 2016) this country has made significant progress in public health, including a consistent de- cline in malaria morbidity and mortality since 1999. Improvement in controlling malaria has been principally achieved by widespread im- plementation of prevention and control measures, including the use of rapid diagnostic tests (RDTs) (MoH, 2010). Between 2000 and 2012, the overall malaria morbidity and mortality have been reduced by 74% and by 83%, respectively (WHO, 2014). In 2012, the Malaria Indicator and Prevalence Survey showed a low parasite prevalence of 1.4% by RDT and 1.1% by microscopy indicating that the country is striving to achieve pre-elimination of malaria (WHO Country Cooperation Strategy 2014–2016: Eritrea). However, in the last three years, incidence of malaria has risen in four regions (Anseba, Debub, Gash-Barka, and Semenawi Keih Bahri) of the country. The immuno-based assay RDT is a diagnostic method that detects malaria antigen in a finger-prick blood sample. The three main groups of antigens detected by RDTs are: Histidine rich protein 2 (PfHRP2), produced by throphozoites and young gametocytes of P. falciparum only; Parasite Lactate Dehydrogenase enzyme (pLDH) (falciparum spe- cific, P. vivax specific or pan specific), and Aldolase pan-specific enzyme (WHO, 2000). PfHRP-2 is a histidine and alanine-rich protein, characterized by a highly polymorphic repeat domain and represents the most common malaria antigen targeted by RDTs for the specific diagnosis of P. falci- parum (Howard et al., 1986). Frequently, a second protein of P. falciparum, the PfHRP3 antigen (Wellems and Howard, 1986) is recognized by PfHRP2-based RDTs (Baker et al., 2010; Lee et al., 2006). In 2010, Gamboa et al. (2010) first documented the deletion of pfhrp2 and pfhrp3 genes in P. falciparum field isolates from Peru and, so far, such deletions have been recorded in many other countries (Houzé http://dx.doi.org/10.1016/j.meegid.2017.09.004 Received 28 March 2017; Received in revised form 4 September 2017; Accepted 5 September 2017 ⁎ Corresponding author at: Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, viale Regina Elena, 299, 00161 Rome, Italy. E-mail address: michela.menegon@iss.it (M. Menegon). Infection, Genetics and Evolution 55 (2017) 131–134 Available online 08 September 2017 1567-1348/ © 2017 Elsevier B.V. All rights reserved. MARK