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.     

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.     

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.     

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.     

Plasmodium ovale malaria acquired in central Spain

We describe a case of locally acquired Plasmodium ovale malaria in Spain. The patient was a Spanish woman who had never traveled out of Spain and had no other risk factors for malaria. Because patients with malaria may never have visited endemic areas, occasional transmission of malaria to European hosts is a diagnostic and clinical challenge.     

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.     

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.     

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.     

Diagnosis of Plasmodium vivax malaria using a specific deoxyribonucleic acid probe

A deoxyribonucleic acid (DNA) probe which specifically distinguishes Plasmodium vivax from P. falciparum malaria has been derived from a P. vivax genomic DNA library. This probe, VPL101, consists of 3.2 kilobase pairs and does not hybridize with up to 6 micrograms of human or P. falciparum DNA. VPL101 contains at least two copies of a 205 base pair repeat sequence. The subcloned repeat probe, VPL101/5, reacted with 73 of 76 microscopically diagnosed P. vivax samples but not with any of 17 human DNA samples or any of 8 P. falciparum DNA samples from cultured parasites. It was possible to detect P. vivax in mixed infections in which only P. falciparum parasites were identifiable by microscopy. This P. vivax DNA probe provides a useful epidemiological tool for malaria control programmes.     

Mosquito surveillance in the Demilitarized Zone, Republic of Korea, during an outbreak of Plasmodium vivax malaria in 1996 and 1997

Since 1993, more than 2,000 cases of vivax malaria have occurred in the Republic of Korea in an epidemic that ended nearly 20 malaria-free years. Most malaria has occurred in the northwestern part of the country, mainly affecting Korean military personnel. As a part of an operational surveillance effort, we sampled mosquitoes in and near the Demilitarized Zone (Paju County, Kyonggi Province) during the last 2 wk of July in 1996 and from May 15 to September 10 in 1997. The 1st year, landing collections were done at 5 different sites; the 2nd year, carbon-dioxide-baited light traps at 5 sites, larval collections in 10 adjacent fields, and landing collections at 1 site in the Demilitarized Zone were performed weekly. Of 17 species collected, Anopheles sinensis was consistently the most abundant mosquito, comprising 79-96% of mosquitoes. The diel pattern of biting by An. sinensis varied by location and season, with the majority of individuals biting late at night during warm weather (>20 degrees C) and early at night during cool weather. In contrast, Aedes vexans nipponii (the 2nd most abundant species) bit in the greatest numbers at the same time all season, from 2000 to 2300 h. Among the correlates with abundance of An. sinensis were average nighttime temperature 2 wk previous to the night in question, wind late at night (negatively correlated), and apparent size of the moon (negatively correlated). The data showed that the exact number of An. sinensis biting could not be estimated from numbers collected in carbon-dioxide-baited light traps. On the other hand, a threshold of 15 An. sinensis per trap night corresponded (88% accuracy) to a threshold of 12 mosquitoes biting 2 adjacent collectors per night. Larval collections were also significantly correlated with landing collections, despite inexact sampling methods and separation of the larval habitat from the site where landing collections were performed. Operational entomology assets using nighttime temperature records, carbon-dioxide-baited light traps, and larval collections should be able to target their efforts in Korea more efficiently.     

Inconsistent condom use among socially excluded heroin users

The study focused in sexual behaviour among socially excluded heroin users, identifying factors associated with inconsistent condom use. Data was collected in the cities of Granada and Seville between July and October 2000, through a structured questionnaire, to 391 participants. Twenty two and 15% of participants have made consistent use of condoms in vaginal sex in the last year with occasional and regular partners respectively. There is a greater likelihood of inconsistent condom use with occasional partners among users who had had oral sex, and who does not know if their partner(s) inject or injected drugs. For regular partners those who have an injecting partner and do not speak with their sexual partners about AIDS have a higher probability to do not use always a condom. For both groups, when always the partner is who propose the use of condoms (when used) and not themselves, the risk not to use it is near 4 times more than when themselves propose to use it. Speaking about condoms and AIDS with mate, partners and family, and learning to negotiate the use of condoms seems to be the most important strategies to be approached for this sample, from the social and health care system in order to promote a protected sex.