Reduction in Plasmodium falciparum Pfk13 and pfg377 allele diversity through time in southern Vietnam.

Background: Plasmodium falciparum has acquired resistance to artemisinin in Southeast Asia, with mutations in the P. falciparum Kelch-13 (Pfk13) gene associated with the resistance phenotype. The widespread use of Artemisinin-based combination therapy (ACT)s in Southeast Asia has led to the selection and spread of parasites carrying mutations in Pfk13.

Effects of Indoor Environmental Factors and House Structures on Vaporization of Active Ingredient from Spatial Repellent Devices in Rural Houses in Malawi.

The use of a metofluthrin-impregnated spatial repellent device (MSRD) is a new and effective method for preventing mosquito blood feeding. Indoor environmental factors such as room temperature and ventilation rate are thought to be important for MSRD activity. Measurements of room temperature and vaporization of metofluthrin from MSRD in typical rural metal-roof and thatched-roof houses in southeastern Malawi were conducted.

Effect of Metofluthrin-Impregnated Spatial Repellent Devices Combined with New Long-Lasting Insecticidal Nets (Olyset Plus) on Pyrethroid-Resistant Malaria Vectors and Malaria Prevalence: Field Trial in South-Eastern Malawi.

Long-lasting insecticidal nets (LLINs) experience some operational problems that reduce their effectiveness, such as limited spaces for hanging, biting of mosquitoes outdoors, a shift of key biting time from midnight to dawn or dusk, and development of pyrethroid resistance in mosquitoes. The concept of spatial repellency may be a countermeasure to overcome the above issues. The effect of the combined use of metofluthrin-impregnated spatial repellent devices (MSRDs) and LLINs (Olyset Plus) on malaria prevalence and vector mosquitoes were examined in malaria endemic villages in south-eastern Malawi.

Human infection with on the Laos-Vietnam border.

Background: Border malaria in the Greater Mekong region of Southeast Asia poses a serious threat to the health of the ethnic minority populations of the region. Traditionally thought to be caused primarily by the malaria parasites and , recently a zoonotic parasite, , has been identified in some countries of the region. The presence of this parasite poses a challenge to malaria control programmes, as it is maintained in a zoonotic reservoir of forest-dwelling macaque monkeys.

Pfcrt genotypes and related microsatellite DNA polymorphisms on Plasmodium falciparum differed among populations in the Greater Mekong Subregion.

Malaria morbidity and mortality have decreased gradually in the Greater Mekong Subregion (GMS). Presently, WHO sets a goal to eliminate malaria by 2030 in the GMS. However, drug-resistant malaria has been reported from several endemic areas.

Detection of the Plasmodium falciparum Kelch-13 gene P553L mutation in sporozoites isolated from mosquito salivary glands in South-Central Vietnam.

Background: Plasmodium falciparum has developed resistance against artemisinin in Southeast Asia. Mutations in the P. falciparum Kelch-13 (Pfk13) gene are associated with artemisinin resistance in vitro and in vivo.

Humans frequently exposed to a range of non-human primate malaria parasite species through the bites of Anopheles dirus mosquitoes in South-central Vietnam.

Background: Recent studies have described natural human infections of the non-human primate parasites Plasmodium knowlesi and Plasmodium cynomolgi. In Southeast Asia, mosquitoes of the Anopheles leucosphyrus group bite both humans and monkeys in the forest and thus offer a possible route for Plasmodium species to bridge the species barrier. In this study we analysed the species composition of malarial sporozoites infecting the salivary glands of Anopheles dirus in order to determine their potential role as bridge vectors of Plasmodium parasites from monkeys to humans.

Detection of Plasmodium knowlesi DNA in the urine and faeces of a Japanese macaque (Macaca fuscata) over the course of an experimentally induced infection.

Background: Diagnostic techniques based on PCR for the detection of Plasmodium DNA can be highly sensitive and specific. The vast majority of these techniques rely, however, on the invasive sampling of blood from infected hosts. There is, currently, considerable interest in the possibility of using body fluids other than blood as sources of parasite DNA for PCR diagnosis.

DNA from pre-erythrocytic stage malaria parasites is detectable by PCR in the faeces and blood of hosts.

Following the bite of an infective mosquito, malaria parasites first invade the liver where they develop and replicate for a number of days before being released into the bloodstream where they invade red blood cells and cause disease. The biology of the liver stages of malaria parasites is relatively poorly understood due to the inaccessibility of the parasites to sampling during this phase of their life cycle. Here we report the detection in blood and faecal samples of malaria parasite DNA throughout their development in the livers of mice and before the parasites begin their growth in the blood circulation.

Genetic diversity and lack of artemisinin selection signature on the Plasmodium falciparum ATP6 in the Greater Mekong Subregion.

The recent detection of clinical Artemisinin (ART) resistance manifested as delayed parasite clearance in the Cambodia-Thailand border area raises a serious concern. The mechanism of ART resistance is not clear; but the P. falciparum sarco/endoplasmic reticulum Ca(2+)-ATPase (PfSERCA or PfATP6) has been speculated to be the target of ARTs and thus a potential marker for ART resistance.

Positive diversifying selection on the Plasmodium falciparum surf4.1 gene in Thailand.

Plasmodium falciparum SURFIN(4.1) is a type I transmembrane protein thought to locate on the merozoite surface and to be responsible for a reversible adherence to the erythrocyte before invasion. In this study, we evaluated surf(4.

Stable allele frequency distribution of the polymorphic region of SURFIN(4.2) in Plasmodium falciparum isolates from Thailand.

Plasmodium falciparum SURFIN₄.₂ (PFD1160w) is a polymorphic protein expressed on the surface of parasite-infected erythrocytes. Such molecules are expected to be under strong host immune pressure, thus we analyzed the nucleotide diversity of the N-terminal extracellular region of SURFIN₄.

Positive selection on the Plasmodium falciparum clag2 gene encoding a component of the erythrocyte-binding rhoptry protein complex.

A protein complex of high-molecular-mass proteins (PfRhopH) of the human malaria parasite Plasmodium falciparum induces host protective immunity and therefore is a candidate for vaccine development. Clarification of the level of polymorphism and the evolutionary processes is important both for vaccine design and for a better understanding of the evolution of cell invasion in this parasite. In a previous study on 5 genes encoding RhopH1/Clag proteins, positive diversifying selection was detected in clag8 and clag9 but not in the paralogous clag2, clag3.

Plasmodium falciparum: differential selection of drug resistance alleles in contiguous urban and peri-urban areas of Brazzaville, Republic of Congo.

The African continent is currently experiencing rapid population growth, with rising urbanization increasing the percentage of the population living in large towns and cities. We studied the impact of the degree of urbanization on the population genetics of Plasmodium falciparum in urban and peri-urban areas in and around the city of Brazzaville, Republic of Congo. This field setting, which incorporates local health centers situated in areas of varying urbanization, is of interest as it allows the characterization of malaria parasites from areas where the human, parasite, and mosquito populations are shared, but where differences in the degree of urbanization (leading to dramatic differences in transmission intensity) cause the pattern of malaria transmission to differ greatly.

Co-infections of Plasmodium knowlesi, P. falciparum, and P. vivax among Humans and Anopheles dirus Mosquitoes, Southern Vietnam.

A single Anopheles dirus mosquito carrying sporozoites of Plasmodium knowlesi, P. falciparum, and P. vivax was recently discovered in Khanh Phu, southern Vietnam.

In vivo and in vitro gametocyte production of Plasmodium falciparum isolates from Northern Thailand.

Understanding why some malaria-infected individuals are infective to mosquitoes while others are not, is of great importance when considering interventions to stop malaria transmission. Whether gametocytes are produced in every individual infected with Plasmodium falciparum remains unclear. Using a highly sensitive reverse transcription (RT)-PCR assay, we attempted to detect gametocyte-specific mRNA transcripts in isolates from Thai patients which newly adapted to continuous in vitro culture.

Longitudinal survey of Plasmodium falciparum infection in Vietnam: characteristics of antimalarial resistance and their associated factors.

Plasmodium falciparum is the main cause of human malaria and is one of the important pathogens causing high rates of morbidity and mortality. The total number of malaria patients in Vietnam has gradually decreased over the last decade. However, the spread of pathogens with drug resistance remains a significant problem.

Anopheles dirus co-infection with human and monkey malaria parasites in Vietnam.

The feasibility of identifying parasite DNA and specific mRNAs from wild-caught Anopheles dirus mosquitoes was assessed using dried mosquito salivary glands preserved on filter paper. We were able to detect Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium knowlesi DNA by conventional PCR and, furthermore, detected P. falciparum gametocyte-specific genes, pfg377 and pfs16 mRNA, P.

Risk factors for malaria infection among ethnic minorities in Binh Phuoc, Vietnam.

A cross-sectional study was undertaken to identify the prevalence of malaria infection, behavioral patterns of inhabitants and risk factors for malaria infection in a minority village in an area endemic for malaria in Vietnam. The target population were all the inhabitants of a village in Binh Phuoc Province, Vietnam. Interviews using a structured questionnaire and blood examination for malaria infection were conducted in house-to-house visits.

A dried blood sample on filter paper is suitable for detecting Plasmodium falciparum gametocytes by reverse transcription polymerase chain reaction.

The detection of gametocytes in human peripheral blood is one of the most important measures in a malaria survey. We attempted to detect gametocytes of Plasmodium falciparum by reverse transcription polymerase chain reaction (RT-PCR) of dried blood on filter paper. On field samples analysis, the specific RT-PCR products for region 3 of pfg377 mRNA were observed in 67 of 131 falciparum malaria patients.

Osteopontin is involved in Th1-mediated immunity against Plasmodium falciparum infection in a holoendemic malaria region in Vietnam.

We examined the role of osteopontin (OPN) in immunity against Plasmodium falciparum infection. We measured the mRNA levels for OPN and several cytokines in RNA preparations extracted from dried blood on filter paper obtained from falciparum malaria patients in Vietnam. Expression of OPN mRNA was detected in 134 of 161 patients.

Osteopontin participates in Th1-mediated host resistance against nonlethal malaria parasite Plasmodium chabaudi chabaudi infection in mice.

Osteopontin (OPN) knockout mice (OPN-KO mice) died of Plasmodium chabaudi chabaudi infection, although wild-type (WT) mice had self-limiting infections. OPN was detected in the WT mice at 2 days postinfection. OPN-KO mice produced significantly smaller amounts of interleukin-12 and gamma interferon than WT mice produced.

Plasmodium berghei NK65: studies on the effect of treatment duration and inoculum size on recrudescence.

Recrudescence of Plasmodium berghei NK65 infection was studied to examine factors affecting recrudescence. Treatment with a high dose of chloroquine did not prevent recrudescence, but an extended duration of treatment suppressed the frequency of recrudescence. Infection with a larger number of parasites also resulted in more frequent recrudescences.

Polymorphism of the Plasmodium falciparum multidrug resistance and chloroquine resistance transporter genes and in vitro susceptibility to aminoquinolines in isolates from the Peruvian Amazon.

In vitro drug sensitivity to chloroquine (CQ), mefloquine (MQ) and quinine was investigated in 60 culture-adapted Plasmodium falciparum isolates from malaria patients in Padrecocha, a village in the Amazonian Department of Loreto, Peru. All isolates showed resistance to CQ, decreased susceptibility to quinine, and sensitivity to MQ. These isolates were examined for mutations in the P.

Identification of a ubiquitin family protein as a novel neutrophil chemotactic factor.

Neutrophil chemotaxis is a process that is essential for the recruitment of neutrophils to an inflamed site. In the present study, we found a remarkable increase in neutrophil chemotactic activity in the lysate of red blood cells (RBC) of mice infected with murine malaria, Plasmodium yoelii. A neutrophil chemotactic factor with an apparent molecular weight of 17 kDa (IP17) was isolated from RBC by a combination of anion-exchange chromatography on DE52 and cation-exchange chromatography on Mono S.