Human-to-Anopheles dirus mosquito transmission of the anthropozoonotic malaria parasite, Plasmodium knowlesi.

Background: Plasmodium knowlesi, identified as the fifth human malaria parasite, has rapidly spread across various Southeast Asian countries, yet uncertainties persist regarding its human-mosquito-human transmission. Therefore, this study aims to explore the transmission potential of P. knowlesi from human blood to mosquitoes.

Knockdown of Anopheles dirus far upstream element-binding protein gene lower oocyst numbers of Plasmodium vivax.

The modulation of gene expression levels of Anopheles dirus on Plasmodium vivax infection at the ookinete and oocyst stages was previously reported. In the present study, several upregulated An. dirus genes were selected based on their high expression levels and subcellular locations to examine their roles in P.

Transmission efficiency of Plasmodium vivax at low parasitaemia.

Background: Plasmodium vivax is responsible for much of malaria outside Africa. Although most P. vivax infections in endemic areas are asymptomatic and have low parasite densities, they are considered a potentially important source of transmission.

Naturally acquired antibody kinetics against Plasmodium vivax antigens in people from a low malaria transmission region in western Thailand.

Background: Plasmodium vivax (P. vivax) is the dominant Plasmodium spp. causing the disease malaria in low-transmission regions outside of Africa.

Detection of Plasmodium Sporozoites in Anopheles Mosquitoes using an Enzyme-linked Immunosorbent Assay.

Plasmodium sporozoites are the infective stage of malaria parasites that infect humans. The sporozoites residing in the salivary glands of female Anopheles mosquitoes are transmitted to humans via mosquito bites during blood feeding. The presence of sporozoites in the mosquito salivary glands thus defines mosquito infectiousness.

Controlled human malaria infection with a clone of Plasmodium vivax with high-quality genome assembly.

Controlled human malaria infection (CHMI) provides a highly informative means to investigate host-pathogen interactions and enable in vivo proof-of-concept efficacy testing of new drugs and vaccines. However, unlike Plasmodium falciparum, well-characterized P. vivax parasites that are safe and suitable for use in modern CHMI models are limited.

Application of 23 Novel Serological Markers for Identifying Recent Exposure to Parasites in an Endemic Population of Western Thailand.

Thailand is aiming for malaria elimination by the year 2030. However, the high proportion of asymptomatic infections and the presence of the hidden hypnozoite stage of are impeding these efforts. We hypothesized that a validated surveillance tool utilizing serological markers of recent exposure to infection could help to identify areas of ongoing transmission.

Anopheles dirus yellow-g mediates Plasmodium vivax infection.

Objective: Our previous transcriptome analysis of Anopheles dirus revealed upregulation of the An. dirus yellow-g gene upon ingestion of Plasmodium vivax-infected blood. This gene belongs to the yellow gene family, but its role regarding P.

Evaluation and modeling of direct membrane-feeding assay with Plasmodium vivax to support development of transmission blocking vaccines.

Standard and direct membrane-feeding assays (SMFA and DMFA) are fundamental assays to evaluate efficacy of transmission-blocking intervention (TBI) candidates against Plasmodium falciparum and vivax. To compare different candidates precisely, it is crucial to understand the error range of measured activity, usually expressed as percent inhibition in either oocyst intensity (% transmission reducing activity, %TRA), or in prevalence of infected mosquitoes (% transmission blocking activity, %TBA). To this end, mathematical models have been proposed for P.

Transcriptome analysis of Anopheles dirus and Plasmodium vivax at ookinete and oocyst stages.

Malaria is transmitted by Plasmodium parasites through the bite of female Anopheles mosquitoes. One of the most important mosquito vectors in the Greater Mekong Subregion is Anopheles dirus. This study reports RNA sequencing (RNA-Seq) transcriptome analysis of An.

Natural Plasmodium vivax infections in Anopheles mosquitoes in a malaria endemic area of northeastern Thailand.

There was recently an outbreak of malaria in Ubon Ratchathani Province, northeastern Thailand. In the absence of information on malaria vector transmission dynamics, this study aimed to identify the anopheline vectors and their role in malaria transmission. Adult female Anopheles mosquitoes were collected monthly by human-landing catch in Na Chaluai District of Ubon Ratchathani Province during January 2014-December 2015.

Very high carriage of gametocytes in asymptomatic low-density Plasmodium falciparum and P. vivax infections in western Thailand.

Background: Low-density asymptomatic infections of Plasmodium spp. are common in low endemicity areas worldwide, but outside Africa, their contribution to malaria transmission is poorly understood. Community-based studies with highly sensitive molecular diagnostics are needed to quantify the asymptomatic reservoir of Plasmodium falciparum and P.

Asymptomatic Plasmodium vivax infections induce robust IgG responses to multiple blood-stage proteins in a low-transmission region of western Thailand.

Background: Thailand is aiming to eliminate malaria by the year 2024. Plasmodium vivax has now become the dominant species causing malaria within the country, and a high proportion of infections are asymptomatic. A better understanding of antibody dynamics to P.

Natural human Plasmodium infections in major Anopheles mosquitoes in western Thailand.

Background: The Thai-Myanmar border is a remaining hotspot for malaria transmission. Malaria transmission in this region continues year-round, with a major peak season in July-August, and a minor peak in October-November. Malaria elimination requires better knowledge of the mosquito community structure, dynamics and vectorial status to support effective vector control.

Acquisition and Longevity of Antibodies to Plasmodium vivax Preerythrocytic Antigens in Western Thailand.

Plasmodium vivax is now the dominant Plasmodium species causing malaria in Thailand, yet little is known about naturally acquired immune responses to this parasite in this low-transmission region. The preerythrocytic stage of the P. vivax life cycle is considered an excellent target for a malaria vaccine, and in this study, we assessed the stability of the seropositivity and the magnitude of IgG responses to three different preerythrocytic P.

Membrane Feeding Assay to Determine the Infectiousness of Plasmodium vivax Gametocytes.

The evaluation of Plasmodium vivax gametocyte infectiousness by the membrane feeding assay is herein described. While P. vivax cannot be cultured and different parasite isolates may infect mosquitoes at different rates, the protocol described in this chapter identifies critical parameters to be considered when performing the assay such as methods for the preparation of the mosquitoes, the size of the blood cup, and the blood volume used.

Differential roles of an Anopheline midgut GPI-anchored protein in mediating Plasmodium falciparum and Plasmodium vivax ookinete invasion.

Novel strategies to directly thwart malaria transmission are needed to maintain the gains achieved by current control measures. Transmission-blocking interventions (TBIs), namely vaccines and drugs targeting parasite or mosquito molecules required for vector-stage parasite development, have been recognized as promising approaches for preventing malaria transmission. However, the number of TBI targets is limited and their degree of conservation among the major vector-parasite systems causing human disease is unclear.

Infectivity of asymptomatic Plasmodium-infected human populations to Anopheles dirus mosquitoes in western Thailand.

The infectivity of Plasmodium-infected humans in western Thailand was estimated by feeding laboratory-reared Anopheles dirus Peyton and Harrison mosquitoes on venous blood placed in a membrane-feeding apparatus. Between May 2000 and November 2001, a total of 6,494 blood films collected during an active malaria surveillance program were checked by microscopy for the presence of Plasmodium parasites: 3.3, 4.

Short report: Failure of the OptiMAL rapid malaria test as a tool for the detection of asymptomatic malaria in an area of Thailand endemic for Plasmodium falciparum and P. vivax.

We evaluated the efficacy of the OptiMAL assay in a cross-sectional malaria survey in western Thailand from April to August 2001. Expert microscopy of Giemsa-stained thick and thin blood films was used as the gold standard. Positive control lines were evident in 99% (1,128 of 1,137) of the assays tested.