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Plasmodium malariae and Plasmodium ovale infections in the China–Myanmar border area
- Source :
- Malaria Journal
- Publication Year :
- 2016
- Publisher :
- Springer Science and Business Media LLC, 2016.
-
Abstract
- Background The Greater Mekong Subregion is aiming to achieve regional malaria elimination by 2030. Though a shift in malaria parasite species predominance by Plasmodium vivax has been recently documented, the transmission of the two minor Plasmodium species, Plasmodium malariae and Plasmodium ovale spp., is poorly characterized in the region. This study aims to determine the prevalence of these minor species in the China–Myanmar border area and their genetic diversity. Methods Epidemiology study was conducted during passive case detection in hospitals and clinics in Myanmar and four counties in China along the China–Myanmar border. Cross-sectional surveys were conducted in villages and camps for internally displaced persons to determine the prevalence of malaria infections. Malaria infections were diagnosed initially by microscopy and later in the laboratory using nested PCR for the SSU rRNA genes. Plasmodium malariae and P. ovale infections were confirmed by sequencing the PCR products. The P. ovale subtypes were determined by sequencing the Pocytb, Pocox1 and Pog3p genes. Parasite populations were evaluated by PCR amplification and sequencing of the MSP-1 genes. Antifolate sensitivity was assessed by sequencing the dhfr-ts and dhps genes from the P. malariae and P. ovale isolates. Results Analysis of 2701 blood samples collected from the China–Myanmar border by nested PCR targeting the parasite SSU rRNA genes identified 561 malaria cases, including 161 Plasmodium falciparum, 327 P. vivax, 66 P. falciparum/P. vivax mixed infections, 4 P. malariae and 3 P. ovale spp. P. vivax and P. falciparum accounted for >60 and ~30% of all malaria cases, respectively. In comparison, the prevalence of P. malariae and P. ovale spp. was very low and only made up ~1% of all PCR-positive cases. Nevertheless, these two species were often misidentified as P. vivax infections or completely missed by microscopy even among symptomatic patients. Phylogenetic analysis of the SSU rRNA, Pocytb, Pocox1 and Pog3p genes confirmed that the three P. ovale spp. isolates belonged to the subtype P. ovale curtisi. Low-level genetic diversity was detected in the MSP-1, dhfr and dhps genes of these minor parasite species, potentially stemming from the low prevalence of these parasites preventing their mixing. Whereas most of the dhfr and dhps positions equivalent to those conferring antifolate resistance in P. falciparum and P. vivax were wild type, a new mutation S113C corresponding to the S108 position in pfdhfr was identified in two P. ovale curtisi isolates. Conclusions The four human malaria parasite species all occurred sympatrically at the China–Myanmar border. While P. vivax has become the predominant species, the two minor parasite species also occurred at very low prevalence but were often misidentified or missed by conventional microscopy. These minor parasite species displayed low levels of polymorphisms in the msp-1, dhfr and dhps genes. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1605-y) contains supplementary material, which is available to authorized users.
- Subjects :
- Male
0301 basic medicine
Plasmodium ovale
Plasmodium vivax
Drug Resistance
Protozoan Proteins
DHPS
Myanmar
Plasmodium malariae
Polymerase Chain Reaction
Genetic diversity
0302 clinical medicine
Prevalence
Cluster Analysis
Parasite hosting
Child
Phylogeny
Microscopy
biology
3. Good health
Infectious Diseases
Female
Adult
China
Plasmodium falciparum
030231 tropical medicine
030106 microbiology
DNA, Ribosomal
Young Adult
03 medical and health sciences
parasitic diseases
RNA, Ribosomal, 18S
medicine
Humans
Research
Genetic Variation
Sequence Analysis, DNA
DNA, Protozoan
biology.organism_classification
medicine.disease
Virology
Malaria
Cross-Sectional Studies
Parasitology
Molecular identification
Subjects
Details
- ISSN :
- 14752875
- Volume :
- 15
- Database :
- OpenAIRE
- Journal :
- Malaria Journal
- Accession number :
- edsair.doi.dedup.....091adf8e2b8e93085adb6caa6e7bf1f1