Genomic surveillance of Plasmodium falciparum and Plasmodium vivax cases at the University Hospital in Tegucigalpa, Honduras

Abstract

Malaria continues to be an important health problem in Honduras despite major progress achieved reducing its incidence in the last two decades. In a context of case reduction, continuing surveillance of parasite diversity and drug resistance is an important component to assist effective malaria control strategies and support risk assessments. In this study, we employed next generation sequencing on collected Plasmodium vivax and P. falciparum samples from the Hospital Escuela (University Hospital) in Honduras between 2005 and 2017. Hospital Escuela is the main public health hospital in Honduras and receives suspected malaria cases from endemic regions within the country. The resulting sequencing data was used to assess complexity of infections, parasite population structure, parasite diversity and drug resistance profiling. All P. vivax samples and all autochtonous P. falciparum samples were monoclonal and presented a low intra population diversity (π = 0.25 and 0.07, respectively). Genotyping of drug resistance markers showed that three P. falciparum samples presented the chloroquine resistant haplotype SVMNT on pfcrtr (positions 72-76). Epidemiological data suggested that two of these samples were imported cases from Africa whereas the third one was a local case. Three suspected imported cases (two of which were also pfcrt mutants) presented the pfmdr1 86Y mutation that further enhances the CQ resistant genotype. No evidence was found for kelch13 artemisinin resistance associated mutations nor parasite genetic background mutations. Discriminant analysis of principal components and phylogenetic analysis showed two P. vivax and two P. falciparum parasite sub-populations with limited recombination between them. It also confirmed the closer relationship of the three imported cases with African strains. Our findings showed that local Honduras P. falciparum strains do not hold CQ resistance polymorphisms which aligns with clinical data reported by the country and supports the continuity of CQ based treatment in Honduras. In addition, our findings highlight the need of using genomic approaches to provide key information about parasite biology including drug resistance, population structure and HRP2/HRP3 deletions which are becoming relevant as the country move towards elimination.

Figure 1

Distribution map of study cases. The colors on the map correspond to the Honduras States were patients came from and the numbers to the cases from each of the states. Most samples came from the department of Francisco Morazan where University Hospital is located. The map was created using open data obtained from GADM database of Global Administrative Areas, version 3.6. URL: http://www.gadm.org.

Figure 2

Clustering results of P. vivax and P. falciparum. The figure shows the population structure of 23 P. vivax samples (inset A) and 7 P. falciparum samples (inset B). The y-axis denotes the membership probability of each sample to a cluster whereas the color shows the two clusters that were identified for P. vivax and P. falciparum. The color scheme corresponds to the two clusters that k-means clustering assigned for each of the species.

Figure 3

Maximum likelihood phylogenetic analysis. The figure shows that the three imported cases (CDR10124, CDR10209 and CDR10057) are closely related to the African and 3D7 strains rather than to Honduras autochthonous cases. Node numbers indicate bootstrap support.