Background: Plasmodium vivax is the most geographically widespread species and is recently associated with severe malaria and leading to death in few cases. In P.vivax drug resistance, vir, and msp3α genes are speculated to play important role in disease severity in natural infections. In this study, we have analyzed thrombocytopenic condition and Pvmsp3α multiplicity of infection (MOI) for disease severity in P.vivax clinical isolates.
Methods: P.vivax samples were collected and diagnosed with microscopy and RMAT. Severity was assessed and correlated with thrombocytopenia and Pvmsp3α gene. PCR assay was done and MOI was calculated for assessing the disease severity in clinical isolates.
Results: A total of 122 clinical samples of P.vivax were collected as per WHO classification, out of which 67 were severe and 55 non-severe infections. By microscopy, parasitemia was calculated but no correlation of parasitemia with disease severity (p-value=0.38) was seen statistically. Among all the P.vivax clinical isolates severe thrombocytopenia was seen in majority of samples and different thrombocytopenic conditions (mild, moderate, and severe thrombocytopenia) in clinical samples showed a significant difference with respect to normal platelet count (p-value<0.05). Molecular genotyping of Pvmsp3α gene in clinical samples revealed four major genotypes viz Type A (1kb), Type B (1.5kb), Type C (2kb), and Type D (2.5kb), out of which Type B (1.5kb) was predominant in severe and Type C (2kb) was predominant in non-severe samples. MOI was correlated with disease severity for all the four genotype, it was seen that Type A and Type D there was no significance difference, whereas for Type B (p-value-0.02) and Type C (p-value-0.0006) significant difference was seen between the two clinical groups.
Conclusion: The severe vivax clinical cases are mostly associated with thrombocytopenia which needs to be studied in detail at molecular and clinical level to understand the disease severity due to vivax malaria.