Molecular markers and genetic diversity of Plasmodium vivax

Enhanced understanding of the transmission dynamics and population genetics for Plasmodium vivax is crucial in predicting the emergence and spread of novel parasite phenotypes with major public health implications, such as new relapsing patterns, drug resistance and increased virulence. Suitable molecular markers are required for these population genetic studies. Here, we focus on two groups of molecular markers that are commonly used to analyse natural populations of P. vivax. We use markers under selective pressure, for instance, antigen-coding polymorphic genes, and markers that are not under strong natural selection, such as most minisatellite and microsatellite loci. First, we review data obtained using genes encoding for P. vivax antigens: circumsporozoite protein, merozoite surface proteins 1 and 3α, apical membrane antigen 1 and Duffy binding antigen. We next address neutral or nearly neutral molecular markers, especially microsatellite loci, providing a complete list of markers that have already been used in P. vivax populations studies. We also analyse the microsatellite loci identified in the P. vivax genome project. Finally, we discuss some practical uses for P. vivax genotyping, for example, detecting multiple-clone infections and tracking the geographic origin of isolates

Dengue Viral Myositis Complicated with Rhabdomyolysis and Superinfection of Methicillin-Resistant Staphylococcus aureus

Dengue is endemic in Sri Lanka and the physician should be aware of different and unusual presentation of the illness. Rhabdomyolysis is a well-known complication following many viral and bacterial infections; however, only a few cases have been reported with dengue viral infections. Further occurrence of coinfection by dengue and bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) has been underestimated, and few reports have been published so far. This case describes a 17-year-old boy who presented with prolonged severe myalgia, dark red urine, and a febrile illness that was diagnosed as having dengue viral myositis, dark red urine, and a febrile illness that was diagnosed as having dengue viral myositis complicated with rhabdomyolysis and superinfection of MRSA. Despite intensive care management, he died due to multiorgan failure. Autopsy and serological studies confirmed the diagnosis. This case stresses that red-coloured urine in dengue patients is not always due to haematuria, and if a patient’s vital signs do not respond to appropriate fluid management in DHF, sepsis from a secondary pathogen including MRSA should be suspected

Epidemiology and Infectivity of Plasmodium falciparum and Plasmodium vivax Gametocytes in Relation to Malaria Control and Elimination

Summary: Malaria remains a major cause of morbidity and mortality in the tropics, with Plasmodium falciparum responsible for the majority of the disease burden and P. vivax being the geographically most widely distributed cause of malaria. Gametocytes are the sexual-stage parasites that infect Anopheles mosquitoes and mediate the onward transmission of the disease. Gametocytes are poorly studied despite this crucial role, but with a recent resurgence of interest in malaria elimination, the study of gametocytes is in vogue. This review highlights the current state of knowledge with regard to the development and longevity of P. falciparum and P. vivax gametocytes in the human host and the factors influencing their distribution within endemic populations. The evidence for immune responses, antimalarial drugs, and drug resistance influencing infectiousness to mosquitoes is reviewed. We discuss how the application of molecular techniques has led to the identification of submicroscopic gametocyte carriage and to a reassessment of the human infectious reservoir. These components are drawn together to show how control measures that aim to reduce malaria transmission, such as mass drug administration and a transmission-blocking vaccine, might better be deployed