Plasmodium vivax malaria

We report 11 cases of severe Plasmodium vivax malaria in Bikaner (western India). Patients exhibited cerebral malaria, renal failure, circulatory collapse, severe anemia, hemoglobinurea, abnormal bleeding, acute respiratory distress syndrome, and jaundice. Peripheral blood microscopy, parasite antigen-based assays, and parasite 18s rRNA gene-based polymerase chain reaction showed the presence of P. vivax and absence of P. falciparum.     

Pyrimethamine resistance in Plasmodium vivax malaria

P. vivax infection (Korean, St Elizabeth or Chesson strain) was induced in 17 neurosyphilitic patients. Pyrimethamine in single doses of either 25, 50, 100 or 200 mg was given to test the schizontocidal and sporontocidal effects.     

Development of vaccines for Plasmodium vivax malaria

Plasmodium vivax continues to cause significant morbidity outside Africa with more than 50% of malaria cases in many parts of South and South-east Asia, Pacific islands, Central and South America being attributed to P. vivax infections. The unique biology of P. vivax, including its ability to form latent hypnozoites that emerge months to years later to cause blood stage infections, early appearance of gametocytes before clinical symptoms are apparent and a shorter development cycle in the vector makes elimination of P. vivax using standard control tools difficult. The availability of an effective vaccine that provides protection and prevents transmission would be a valuable tool in efforts to eliminate P. vivax. Here, we review the latest developments related to P. vivax malaria vaccines and discuss the challenges as well as directions toward the goal of developing highly efficacious vaccines against P. vivax malaria.     

Contribution of inflammasome genetics in Plasmodium vivax malaria

Recent reports showed that, in mice, symptomatic Plasmodium infection triggers NLRP3/NLRP12-dependent inflammasome formation and caspase-1 activation in monocytes. In humans, few works demonstrated that inflammasome is activated in malaria. As Plasmodium vivax is a potent inducer of inflammatory response we hypothesised that inflammasome genetics might affect P. vivax malaria clinical presentation. For this purpose, selected SNPs in inflammasome genes were analysed among patients with symptomatic P. vivax malaria.157 Brazilian Amazon patients with P. vivax malaria were genotyped for 10 single nucleotide polymorphisms (SNPs) in inflammasome genes NLRP1, NLRP3, AIM2, CARD8, IL1B, IL18 and MEFV. Effect of SNPs on hematologic and clinical parameters was analysed by multivariate analysis.Our data suggested an important role of NLRP1 inflammasome receptor in shaping the clinical presentation of P. vivax malaria, in term of presence of fever, anaemia and thrombocytopenia. Moreover IL1B rs1143634 resulted significantly associated to patients' parasitaemia, while IL18 rs5744256 plays a protective role against the development of anaemia.Polymorphisms in inflammasome genes could affect one or other aspects of malaria pathogenesis. Moreover, these data reveal novel aspects of P. vivax/host interaction that involved NLRP1-inflammasome.     

Neonatal Plasmodium vivax malaria: an overlooked entity

Although malaria is endemic in India, neonatal disease is considered rare. We report a case of neonatal malaria in a 26-day-old neonate with fever and splenomegaly who was diagnosed after a long and unsuccessful battery of tests for splenomegaly. Routine screening for malaria is essential for all neonates with fever in endemic areas. Early diagnosis and treatment of malaria could effectively prevent infant mortality.     

Geographic subdivision of the range of the malaria parasite Plasmodium vivax

We examined geographically distinct isolates of Plasmodium vivax and categorized them according to developmental success in Anopheles albimanus. We found that parasites from Central America and Colombia form a group distinct from those of Asia. New World isolates have a distinct chromosomal translocation and an episomal variation in the open reading frame (ORF) 470 DNA sequence that distinguishes them from the other isolates tested. Old World types of P. vivax were introduced into the Americas, and a remnant of this lineage remains in P. simium. It is indistinguishable from Old World P. vivax to the extent determinable by using our encoded markers and the examination of its developmental pattern in mosquitoes. The cohesive characteristics that separate types of P. vivax are predictors of range and potential for transmission and hence require taxonomic distinction.     

Reemergence of Plasmodium vivax malaria in the republic of Korea.

Plasmodium vivax malaria reemerged in the Republic of Korea in 1993. The number of cases has tripled each year since, with more than 1,600 cases reported in 1997. All 27 cases in U.S. troops resolved uneventfully with chloroquine/primaquine therapy. Disease is localized along the western Demilitarized Zone and presents minimal risk to tourists.     

Congenital malaria due to Plasmodium vivax: a case report from Sri Lanka

A case of Plasmodium vivax malaria in an eight-week-old infant in Colombo is documented, with epidemiological and circumstantial evidence which strongly supports a transplacental route of infection. The malarial antibody levels detected by the indirect fluorescent antibody technique in both mother and child are discussed in terms of the present epidemiological pattern of malaria in the country. We also comment on the species incidence of congenital malaria, this case being the first caused by P. vivax in Sri Lanka, despite this species being more prevalent than P. falciparum which has been reported in six previous cases of congenital malaria in Sri Lanka.     

An outbreak of Plasmodium vivax malaria among heroin users in Spain

We report the first outbreak of induced malaria among heroin users in Spain, and the first one caused by Plasmodium vivax in Europe. Five drug addicts from Madrid, who had never travelled to endemic areas, were admitted to hospital with fever and splenomegaly. Four had P. vivax malaria with low parasitaemia, ranging from 1 to 3% red blood cells. The fifth case was considered a "seropositive contact" because he had fever and positive malaria indirect fluorescent antibody test but negative blood smear. The source of infection was a young drug addict, who had often travelled to Equatorial Guinea. Another heroin user with a diagnosis of malaria refused to be admitted to our hospital for further study. All had shared contaminated injection equipment. Treatment with chloroquine was effective and none had recrudescence of malaria during a mean follow-up of six months. Drug addicts with unexplained fever may have been infected by malaria transmitted by sharing injections.     

Reduction in erythrocytic GSH level and stability in Plasmodium vivax malaria

The existence of haemolytic anaemia in malaria indicates disturbances in red cell stability due to physical as well as metabolic stress attributable to the malarial parasite. As erythrocytic reduced glutathione (GSH) is involved in maintaining the integrity of red cells, the status of erythrocytic GSH was studied in 40 patients infected with Plasmodium vivax before and after therapy with chloroquine. 40 normal subjects, age- and sex-matched, were studied as controls. The level of erythrocytic GSH of malaria patients during infection and before therapy was significantly lower in comparison with controls (P less than 0.0005). Instability of GSH was recorded in 17 of 40 patients, while none of the controls showed such a defect. There was a progressive decrease in GSH level and stability of the host red cells with increasing parasitaemia. Normal values were obtained following therapy and cure of malaria indicating that the changes in GSH level and stability are induced by P. vivax. Alterations in the GSH metabolism may represent one of the factors contributing to the severity of anaemia in malaria due to P. vivax infection.     

Seasonality of presentation of imported Plasmodium vivax malaria in Birmingham, UK

Residents of the UK returning from northern Pakistan with Plasmodium vivax infection tend to developsymptoms and present to hospital in the summer months, irrespective of the month of return. Thus, infections acquired in the cooler months of November to April appear to have a longer latency before presentation. Experiments suggest that more hypnozoites arise from the liver when ambient temperatures fall, somehow ‘programming’ parasites within biting mosquitoes.     

Diagnosis of Plasmodium falciparum infection using a solid-phase radioimmunoassay for the detection of malaria antigens

A serodiagnostic test has been developed for the detection of Plasmodium falciparum in infected blood. Using parasite antigens and infected red blood cells from in vitro cultures of P. falciparum and malaria antibody from high-titre Gambian sera, parasites were detected in a solid-phase radioimmunoassay (RIA) that measured antibody-binding inhibition. Lysed RBC were incubated with labelled IgG purified from immune sera and were then placed in antigen-coated microtubes and incubated. The degree of inhibition of antibody binding in the tubes correlated with the level of parasitaemia in the test RBC and, using dilutions of RBC from in vitro cultures of P. falciparum, the test detected infection at a level of 8 parasites/10⁶ red blood cells. The test was applied to RBC from 100 healthy European blood donors and to samples of RBC from 500 Gambians from the up-country villages of Keneba and Manduar. More samples were positive by RIA than by microscopy and there was a highly significant degree of correlation between the RIA and microscopy results.     

Concurrent dengue and malaria due to Plasmodium falciparum and P. vivax

Concurrent infections of dengue and malaria are rare. We report a case of dengue fever with acute malaria due to Plasmodium falciparum and P. vivax in which the presence of mixed infection with P. vivax was overlooked and confirmed later on during recurrence of the fever that had initially responded to conventional antimalarial treatment and symptomatic treatment for dengue fever. We suggest that in concurrent infections of dengue and malaria, possibility of mixed infection with various Plasmodium species should be excluded to ensure a better treatment outcome.     

Haematinic treatment of anaemia increases the risk of Plasmodium vivax malaria in pregnancy

Nutritional deficiency and malaria are 2 major causes of anaemia during pregnancy in tropical areas. The relationship between anaemia, its treatment with iron and folate, and malaria was studied in a prospective cohort of 2112 pregnant Karen women on the north-western border of Thailand between 1993 and 1997. The development of Plasmodium vivax malaria was associated with a past mean haematocrit > 30% (hazard ratio = 1.5, 95% CI 1.2-2, P = 0.001) and recent (< or = 30 d) iron and folate supplementation (hazard ratio = 1.7, 95% CI 1.1-2.6, P = 0.01). There were no associations with P. falciparum infections. Plasmodium vivax has a predilection for young erythrocytes, and these results suggest that pregnant women with larger numbers of circulating young red cells are at greater risk of developing P. vivax malaria. In P. vivax-endemic areas, systematic iron and folate supplementation confers both benefit and risk in pregnancy.