Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PLASMODIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources
PubMed1999

Murine gamma delta T lymphocytes elicited during Plasmodium yoelii infection respond to Plasmodium heat shock proteins.

gamma delta T cells accumulate during Plasmodium infections in both murine and human malarias. The biological role of these cells and the antigens that they recognize are not clearly understood, although recent findings indicate that gamma delta T cells in general influence both innate and antigen-specific adaptive host responses. We examined the accumulation of gamma delta T cells elicited during infection with virulent and avirulent Plasmodium yoelii parasites in relatively susceptible and resistant strains of mice. Our results indicated that in nonlethal malaria infections, gamma delta T cells comprise a larger proportion of splenic T cells than in lethal infections and that only a live infection is capable of inducing an increase in the percentage of gamma delta T cells in vivo. Furthermore, we demonstrate that gamma delta T cells elicited during a P. yoelii infection respond by proliferation in vitro to P. falciparum heat shock proteins (HSPs) of 60 and 70 kDa, suggesting a possible immunological involvement of parasite HSPs in this arm of the cellular immune response during malarial infection in mice.

Animals↗
PubMed2000

Prevalence of malaria parasites (Plasmodium floridense and Plasmodium azurophilum) infecting a Puerto Rican lizard (Anolis gundlachi): a nine-year study.

The prevalence of malaria parasites was studied in the lizard Anolis gundlachi over a 9-yr period at a site in the wet evergreen forest of eastern Puerto Rico. Three forms of the parasite infected the lizards; these were Plasmodium floridense, Plasmodium azurophilum in erythrocytes, and P. azurophilum in white blood cells. Overall prevalence of infection for 8 samples during the study period was significantly higher for males than females (32% of 3,296 males and 22% of 1,439 females). During the study, the site experienced substantial climatic and physical disturbance including rising temperature, droughts, and hurricanes that severely damaged the forest. Parasite prevalence in the first sample, 8 mo after the massive hurricane Hugo, was slightly, though significantly, lower than for subsequent samples. However, overall prevalence was stable during the 9-yr period. The results show malaria prevalence is more constant at the site than found for 2 studies in temperate forests, and that the Puerto Rico system may be an example of the stable, endemic malaria described by standard models for human malaria epidemiology.

Animals↗
PubMed2005

Plasmodium-infected Anopheles mosquitoes collected in Virginia and Maryland following local transmission of Plasmodium vivax malaria in Loudoun County, Virginia.

Two recent outbreaks of locally acquired, mosquito-transmitted malaria in Virginia in 1998 and 2002 demonstrate the continued risk of endemic mosquito-transmitted malaria in heavily populated areas of the eastern United States. Increasing immigration, growth in global travel, and the presence of competent anopheline vectors throughout the eastern United States contribute to the increasing risk of malaria importation and transmission. On August 23 and 25, 2002, Plasmodium vivax malaria was diagnosed in 2 teenagers in Loudoun County, Virginia. The Centers for Disease Control and Prevention (CDC) deemed these cases to be locally acquired because of the lack of risk factors for malaria, such as international travel, blood transfusion, organ transplantation, or needle sharing. The patients lived approximately 0.5 mi apart; however, 1 patient reported numerous visits to friends who lived directly across the street from the other patient. Two Anopheles quadrimaculatus s.l. female pools collected in Loudoun County, Virginia, and 1 An. punctipennis female pool collected in Fairfax County, Virginia, tested positive for P. vivax 210 with the VecTest panel assay and enzyme-linked immunosorbent assay (ELISA). In addition, 2 An. quadrimaculatus s.l. female pools collected in Montgomery, Maryland, tested positive for P. vivax 210. The CDC confirmed these initial results with the circumsporozoite ELISA. The authors believe that this is the 1st demonstration of Plasmodium-infected mosquitoes collected in association with locally acquired human malaria in the United States since the current national malaria surveillance system began in 1957.

Adolescent↗
PubMedDate not supplied

Antibodies to lactate dehydrogenase of Plasmodium knowlesi are specific to Plasmodium species.

Polyclonal immune monkey serum raised against schizonts of Plasmodium knowlesi (H-strain) showed the presence of antibodies to lactate dehydrogenase (LDH) of P. knowlesi by immunodot enzyme staining method. The anti-LDH antibodies are most probably directed towards an epitope distinct from the catalytic site as shown by the specific enzyme staining of LDH after binding with antibody on nitrocellulose paper. These antibodies showed reactivity with LDH from different strains (H, P and W1 strains of P. knowlesi) and species (P. cynomolgi B, P. berghei, P. yoelii, P. falciparum and P. vivax) of malarial parasites but did not cross-react with three isoenzymic forms of mammalian LDH (A4, B4 and C4) as well as with LDH from some protozoan and helminth parasites. These findings suggest that the anti-LDH antibodies have defined specificity to Plasmodium spp.

Animals↗
PubMed1982

Survival of mice injected with Plasmodium vinckei or Plasmodium yoelii XL by the footpad route.

NIH-white mice were injected with varying doses of Plasmodium vinckei or Plasmodium yoelii lethal via the hind footpad (FP), intraperitoneal (IP), subcutaneous (SC) routes. Survival was dependent on the dose of the inoculum and route of injection. Injection via the IP and SC routes led to higher mortality than the FP route. The results showed that at a dose of 10 4 parasitized erythrocytes injected IP led to 100% mortality, whereas the same dose injected via the FP route gave protection.

Animals↗
PubMed2003

Transmission of mixed Plasmodium species and Plasmodium falciparum genotypes.

We studied malaria transmission by comparing parasite populations in humans and mosquito vectors at the household level. Blood samples were collected from all inhabitants for microscopic detection of gametocytes and polymerase chain reaction analysis. The next morning, blood-fed resting mosquitoes were collected inside the bed nets used by the individuals surveyed the previous afternoon. After 8 days of maintenance, mosquitoes were dissected, and midguts and salivary glands were recovered for polymerase chain reaction analysis. Results showed that parasite distribution was the same in the 2 hosts when compared at each household but was different when whole populations were analyzed. Different associations of Plasmodium species seem to occur in humans (Plasmodium falciparum/Plasmodium malariae) and mosquitoes (P. falciparum/Plasmodium ovale). Regarding P. falciparum infections, a higher proportion of single-genotype infections and less allele diversity are observed in mosquitoes than in humans.

Adolescent↗
PubMed2003

Taxonomic status and re-description of Plasmodium relictum (Grassi et Feletti, 1891), Plasmodium maior Raffaele, 1931, and description of P. bigueti n. sp. in sparrows.

The first accurate re-description of Plasmodium relictum (Grassi et Feletti, 1891) in its type host was provided by Raffaele in 1931, and the name relictum should thus refer to this work. In his article, Raffaele noted the presence of an associated but distinct species, P. maior. The work of Raffaele has since remained overlooked, and the taxon relictum has been applied rather loosely to parasites found in numerous birds of diverse geographic origin. Examination of Passer domesticus specimens collected in France has confirmed the presence of the two species above, and further revealed that two other species can also be found in these birds. P. bigueti n. sp. is described here, whereas the other Plasmodium sp. was not found in sufficient numbers to allow characterisation.

Animals↗
PubMed2005

Plasmodium simium and Saimiri boliviensis as a model system for testing candidate vaccines against Plasmodium vivax.

Observations on Plasmodium simium infections in Saimiri boliviensis boliviensis monkeys suggest that this host-parasite combination would be a suitable model for the testing of candidate vaccines against Plasmodium vivax. To evaluate the normal course of infections, parasitemia in 52 splenectomized S. boliviensis boliviensis monkeys infected with P. simium were analyzed. The mean maximum parasite count for 31 monkeys after injection with trophozoite-infected erythrocytes was 77,580/microL. Twenty-one monkeys were infected via sporozoites, and prepatent periods ranged from 14 to 24 days with a median of 15 days. The mean maximum parasite count was 29,234/microL. The mean maximum parasite count for monkeys previously infected with Old World P. vivax was 26,337/microL versus 56,362/microL for those previously infected with New World P. vivax, possibly suggesting a closer antigenic relationship between P. simium and the Old World parasites.

Animals↗
PubMed1994

The role of free radicals and antioxidative enzymes in erythrocytes and liver cells in the course of Plasmodium berghei and Plasmodium vinckei infection of mice.

Blood schisontocidal test of D0 + D3 type revealed different characteristics of the Plasmodium berghei and Plasmodium vinckei infection. Both types of the rodent plasmodia kill the untreated mice. Chloroquine treatment alone does not prevent the death of the P. berghei infected animals and they died at a low level of parasitaemia. The animals cured with chloroquine plus MAP survive. The infection with P. vinckei produces a high level of parasitaemia and the chloroquine treatment alone prevents the death of mice. The difference in the pathogenic characteristics between P. berghei and P. vinckei is manifested in the results measuring the kinetics of the activity of antioxidative enzymes in the red blood and liver cells of the infected mice: lipid peroxidation (LPO), superoxide dismutases (SOD), glutathione peroxidase (GP), catalase (CAT) and reduced glutathione (GSH). The rapid increase of the LPO in the RBC in particular in the P. vinckei infected animals indicates the prevailing role of the membrane detoxification process. A continuous increase in the activity of enzymes of cytoplasmic origin, e.g. SOD and GP was also observed. A powerful increase in GSH distinguishes the erythrocytes of P. vinckei infected animals. Similar but not identical data characterize the enzyme activities of the liver cells of the plasmodia infected animals.

Animals↗
PubMed1997

Plasmodium forresteri n. sp., from raptors in Florida and southern Georgia: its distinction from Plasmodium elongatum morphologically within and among host species and by vector susceptibility.

Plasmodium forresteri n. sp. naturally infects eastern screech-owls (Otus asio), great horned owls (Bubo virginianus), barred owls (Strix varia), bald eagles (Haliaeetus leucocephalus), red-shouldered hawks (Buteo lineatus), broad-winged hawks (Buteo platypterus), and red-tailed hawks (Buteo jamaicensis) in Florida and southern Georgia. Schizonts occur in mature or nearly mature erythrocytes, produce 2-6 merozoites arranged most commonly in fan or cruciform configuration, with mean dimensions among host species varying from 3.7 to 4.8 x 2.5 to 3.4 microns. Gametocytes are elongate, with mean dimensions among host species varying from 11.5 to 13.1 x 2.0 to 2.4 microns. One or both gametocyte margins are irregular and often crenulate. Gametocytes seldom fill the space between the erythrocyte nucleus and margin. Species characteristics were maintained in isodiagnostic Japanese quail (Coturnix japonica) and Pekin ducks (Anas platyrhynchos). In mosquito infection studies, only Culex restuans could support sporogony of P. forresteri, in contrast to Plasmodium elongatum of raptor origin that completed sporogony in both Cx. restuans and Culex nigripalpus.

Animals↗
PubMed1990

Reduced antibody response to the repetitive sequence of the Plasmodium falciparum circumsporozoite protein in mice infected with Plasmodium yoelii blood forms.

The immunogenicity of the carrier-free synthetic peptide, (NANP)40, from the repetitive region of the Plasmodium falciparum circumsporozoite (CS) protein was investigated in genetically responder mice (C57BL/6, H-2b) acutely infected with blood forms of the non-lethal murine malaria parasite, P. yoelii. As compared to non-infected mice, P. yoelii-infected C57BL/6 mice produced significantly lower titers of anti-(NANP)40 IgG antibodies. This decrease in the anti-(NANP)40 antibody response peaked with the peak of parasitemia, and involved all the IgG subclasses. Interestingly, this P. yoelii-mediated effect was evident both on the development of the antibody response to the (NANP)40 peptide, and on an already established anti-(NANP)40 antibody titer, as seen in mice immunized with the peptide 1 month before the infection. Since (NANP)n-based constructs are strongly envisaged as potential vaccines against falciparum malaria, these results might be important in the evaluation of the efficacy of these vaccine candidates, when they will be used in individuals living in endemic areas.

Amino Acid Sequence↗
PubMed1989

Comparison of the primary structure of the 25 kDa ookinete surface antigens of Plasmodium falciparum and Plasmodium gallinaceum reveal six conserved regions.

The gene encoding the 25 kDa ookinete surface antigen (Pgs25) of Plasmodium gallinaceum has been cloned using an oligonucleotide probe directed against one of the EGF-like domains of the P. falciparum 25 kDa ookinete surface antigen (Pfs25). The Pgs25 gene codes for a polypeptide of 215 amino acids, two amino residues less than Pfs25. The deduced amino acid sequence contains a putative signal sequence at the amino-terminus, four tandemly repeated EGF-like domains, and a hydrophobic region at the carboxyl-terminus. By comparing Pgs25 with Pfs25, six conserved regions, consisting of six or more amino acid residues, have been identified. Most of the conserved regions are outside EGF-like core consensus sequences. The most striking conservation is the spacing of the cysteines.

Amino Acid Sequence↗
PubMed1995

Parasitized erythrocyte membrane antigens of Plasmodium brasilianum: relationships with the ring-infected erythrocyte surface antigen of Plasmodium falciparum.

An antigen, designated here as the parasitized erythrocyte membrane antigen (PEMA), is present in the erythrocyte membrane surrounding all intraerythrocytic stages of Plasmodium brasilianum. An antibody specific for PEMA appeared in 21 (50%) of 42 antisera from Saimiri sciureus monkeys naturally infected with P. brasilianum. Of these 42 sera, nine (21.4%) contained antibody to the ring-infected erythrocyte membrane antigen (RESA); of these nine sera, six did not react with PEMA. Sera of humans infected with P. malariae reacted with PEMA and RESA in a similar pattern; i.e., of 83 antisera, 71 (85.5%) reacted with PEMA and 30 (36%) reacted with RESA. Only one of these latter 30 sera were not reactive with PEMA. Of 167 sera from humans infected with P. falciparum but not P. malariae, 133 (79.6%) reacted with RESA; of these, 43 (25.7% of the total) reacted with PEMA but not RESA. Although PEMA was demonstrated with P. brasilianum and RESA with P. falciparum, neither PEMA or RESA could be demonstrated with P. malariae. Interactions of PEMA and RESA and the corresponding antibodies offer a method whereby the two morphologically similar quartan species, P. malariae and P. brasilianum, can be readily distinguished from each other and may furnish clues to genetic separation of the two and the mechanisms of interaction of quartan malaria and P. falciparum where they are coendemic.

Animals↗
PubMed2006

Mefloquine is highly efficacious against chloroquine-resistant Plasmodium vivax malaria and Plasmodium falciparum malaria in Papua, Indonesia.

BACKGROUND: During the period of 1996-1999, we prospectively monitored 243 Javanese adults and children after arriving in Papua, Indonesia, and microscopically documented each new case of malaria by active surveillance. METHODS: In a randomized, open-label, comparative malaria treatment trial, 72 adults and 50 children received chloroquine for each incident case of malaria, and 74 adults and 47 children received mefloquine. RESULTS: Among 975 primary treatment courses, the cumulative 28-day curative efficacies were 26% and 82% for chloroquine against Plasmodium falciparum malaria and Plasmodium vivax malaria, respectively. Mefloquine cure rates were far superior (96% against P. falciparum malaria and 99.6% against P. vivax malaria). CONCLUSIONS: Mefloquine is a useful alternative treatment for P. vivax malaria and P. falciparum malaria in areas such as Papua, where chloroquine is still recommended as the first-line therapeutic agent.

Adult↗
PubMed2004

Evaluation of a rapid whole blood immunochromatographic assay for the diagnosis of Plasmodium falciparum and Plasmodium vivax malaria.

OBJECTIVE: Microscopic examination of blood smears is the 'gold standard' for malaria diagnosis, but is labour intensive and requires skilled operators. Plasmodium vivax malaria accounts for up to 70% of infections in Sri Lanka. The objective of this study was to determine the effectiveness of an immunochromatographic test which can detect both the species of Plasmodium, P. vivax and P. falciparum, present in Sri Lanka. DESIGN: Prospective study from May 2001 to March 2002. SETTING AND METHODS: All persons above 5 years of age who presented to the Malaria Research Station, Kataragama or the Anti-malaria Clinic, Kurunegala, with a history of fever were recruited to the study. Thick and thin blood smears were examined for malarial parasites. The rapid diagnostic test (RDT), ICT Malaria P.f/P.v (AMRAD ICT, Australia) was performed simultaneously by an independent investigator. The severity of clinical disease of all patients was evaluated. RESULTS: The study sample comprised 328 individuals of whom 126 (38%) were infected, 102 with P. vivax (31.1%) and 24 with P. falciparum (7.3%). The RDT was found to be highly sensitive (100%) and specific (100%) for the diagnosis of P. falciparum when compared with field microscopy. The sensitivity for the diagnosis of P. vivax malaria was only 70%. When P. vivax parasitaemia was greater than 5000 parasites/microL the RDT was 96.2% sensitive. A significant association was noted between the band intensity on the dipstick and both peripheral blood parasitaemia (p < 0.001) and clinical severity of disease with P. vivax (p = 0.011). CONCLUSIONS: The ICT Malaria P.f/P.v test can be used in Sri Lanka in the absence of microscopists.

Adolescent↗
PubMed1997

Laboratory and field comparisons of adenosine influx in Plasmodium falciparum and Plasmodium vivax infected erythrocytes with genetic abnormalities from patients in Myanmar.

Influx of the purine nucleoside, adenosine, was assessed in erythrocytes from both normal subjects and from subjects with a range of genetically determined erythrocyte disorders from Myanmar. The latter included alpha-thalassemia major (Myanmar variant), beta-thalassemia major (Myanmar variant), beta-thalassemia trait, HbEE and HbAE erythrocytes and two variants of glucose-6-phosphate dehydrogenase (G6PDH) deficiency. Significant reductions (p < 0.01) of adenosine influx were observed in erythrocytes from individuals with alpha- and beta-thalassemia major and severe G6PDH deficiency. Abnormal erythrocytes infected with the malarial parasites, Plasmodium falciparum or Plasmodium vivax, demonstrated a reduction in adenosine transport which correlated with the proportion of abnormal erythrocytes present in the samples obtained. The effect of nitrobenzylthioinosine (NBMPR) on adenosine influx was explored in normal and abnormal erythrocytes. In all these cases, NBMPR completely inhibited the transport of adenosine. However, transport of adenosine into P. falciparum and P. vivax-infected normal erythrocytes and abnormal cells was only inhibited 50-60% by NBMPR. The combination of tubercidin and NBMPR completely blocked adenosine transport into both normal and abnormal erythrocytes infected with either P. falciparum or P. vivax.

Adenosine↗
PubMed1995

Plasmodium falciparum and Plasmodium berghei: effect of magnesium on the development of parasitemia.

The in vitro growth of Plasmodium falciparum was reduced by 35 and 43% through high concentrations (5 mmole/liter) of magnesium in RPMI medium and magnesium-free medium, respectively, after 48 hr, whereas no significant inhibition could be observed under these conditions after 24 hr cultivation in the respective medium. Levels of magnesium between 0.5 and 3 mmole/liter showed no inhibitory effect on the in vitro growth of P. falciparum even after long-term exposure for 7 days. The 50 and 90% chloroquine inhibitory concentrations of the chloroquine-resistant strain K1 after 24 hr were reduced to some extent in the presence of magnesium at 5 mmole/liter, but less than in the presence of verapamil at 10 mumole/liter, which showed intrinsic activities at this concentration and which completely reversed resistance. However, high physiologic magnesium plasma levels were associated with a significantly longer survival time of NMRI mice infected with P. berghei strain ANKA, compared to normal physiological plasma magnesium levels. It is concluded that in the case of clinically symptomatic magnesium deficiency, supplementation of magnesium will not aggravate concomitant plasmodial infections and therefore should not be withheld.

Analysis of Variance↗