Malaria surveillance from both ends: concurrent detection of Plasmodium falciparum in saliva and excreta harvested from Anopheles mosquitoes

Malaria remains a major public health problem in many countries. Unlike influenza and HIV, where diversity in immunodominant surface antigens is understood geographically to inform disease surveillance, relatively little is known about the global population structure of PfEMP1, the major variant surface antigen of the malaria parasite Plasmodium falciparum. The complexity of the var multigene family that encodes PfEMP1 and that diversifies by recombination, has so far precluded its use in malaria surveillance. Recent studies have demonstrated that cost-effective deep sequencing of the region of var genes encoding the PfEMP1 DBLα domain and subsequent classification of within host sequences at 96% identity to define unique DBLα types, can reveal structure and strain dynamics within countries. However, to date there has not been a comprehensive comparison of these DBLα types between countries. By leveraging a bioinformatic approach (jumping hidden Markov model) designed specifically for the analysis of recombination within var genes and applying it to a dataset of DBLα types from 10 countries, we are able to describe population structure of DBLα types at the global scale. The sensitivity of the approach allows for the comparison of the global dataset to ape samples of Plasmodium Laverania species. Our analyses show that the evolution of the parasite population emerging out of Africa underlies current patterns of DBLα type diversity. Most importantly, we can distinguish geographic population structure within Africa between Gabon and Ghana in West Africa and Uganda in East Africa. Our evolutionary findings have translational implications in the context of globalization. Firstly, DBLα type diversity can provide a simple diagnostic framework for geographic surveillance of the rapidly evolving transmission dynamics of P. falciparum. It can also inform efforts to understand the presence or absence of global, regional and local population immunity to major surface antigen variants. Additionally, we identify a number of highly conserved DBLα types that are present globally that may be of biological significance and warrant further characterization.

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Surveillance of genetic markers associated with Plasmodium falciparum resistance to artemisinin-based combination therapy in Pakistan, 2018-2019

10.21203/rs.3.rs-16248/v1 ◽

2020 ◽

Author(s):

Abdul Qader Khan ◽

Leyre Pernaute-Lau ◽

Aamer Ali Khattak ◽

Sanna Luijcx ◽

Berit Aydin-Schmidt ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Molecular Markers ◽

Southeast Asia ◽

Treatment Guidelines ◽

Treatment Guideline ◽

Artemisinin Resistance ◽

Chloroquine Resistance ◽

Close Monitoring ◽

Malaria Surveillance ◽

Current Prevalence

Abstract Background: The spread of artemisinin resistance in the Greater Mekong Subregion of Southeast Asia poses a significant threat for current anti-malarial treatment guidelines globally. The aim of this study was to assess the current prevalence of molecular markers of drug resistance in Plasmodium falciparum in the four provinces with the highest malaria burden in Pakistan, after introducing artemether-lumefantrine as first line treatment in 2017.Methods: Samples were collected during routine malaria surveillance in Punjab, Sindh, Baluchistan, and Khyber Pakhtunkhwa provinces of Pakistan between January 2018 and February 2019. P. falciparum infections were confirmed by rapid diagnostic test or microscopy. P. falciparum positive isolates (n = 179) were screened by Sanger sequencing for single nucleotide polymorphisms (SNPs) in the P. falciparum kelch 13 (pfk13) propeller domain and in P. falciparum coronin (pfcoronin). SNPs in P. falciparum multidrug resistance 1 (pfmdr1) N86Y, Y184F, D1246Y and P. falciparum chloroquine resistance transporter (pfcrt) K76T were genotyped by PCR-restriction fragment length polymorphism. Results: No artemisinin resistance associated SNPs were identified in the pfk13 propeller domain or in pfcoronin. The pfmdr1 N86, 184F, D1246 and pfcrt K76 alleles associated with reduced lumefantrine sensitivity were present in 83.8% (150/179), 16.9% (29/172), 100.0% (173/173), and 8.4% (15/179) of all infections, respectively. The chloroquine resistance associated pfcrt 76T allele was present in 98.3% (176/179) of infections.Conclusion: This study provides an update on the current prevalence of molecular markers associated with reduced sensitivity to artemether and/or lumefantrine in P. falciparum, including a first baseline assessment of polymorphisms in pfcoronin. No mutations associated with artemisinin resistance were observed in pfk13 or pfcoronin. However, the prevalence of the pfmdr1 N86 and D1246 alleles, that have been associated with decreased susceptibility to lumefantrine, remain high. Although clinical and molecular data suggest that the current malaria treatment guideline for P. falciparum are presently effective in Pakistan, close monitoring for artemisinin and lumefantrine resistance will be critical to ensure early detection and enhanced containment of emerging ACT resistance spreading across from Southeast Asia.

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Is rapid diagnostic test (malaria Pv/Pf Ag card test) reliable in diagnosing malaria

International Journal of Contemporary Pediatrics ◽

10.18203/2349-3291.ijcp20175565 ◽

2017 ◽

Vol 5 (1) ◽

pp. 92

Author(s):

Vishruti Gandhi Vishruti Gandhi ◽

Prasad Muley ◽

Niyati Parikh ◽

Hardik Gandhi ◽

Akash Mehta

Keyword(s):

Plasmodium Falciparum ◽

Plasmodium Vivax ◽

Diagnostic Test ◽

Rapid Diagnostic Test ◽

Sensitivity And Specificity ◽

Peripheral Blood Smear ◽

Peripheral Smear ◽

Infected Female ◽

Anopheles Mosquitoes ◽

Smear Examination

Background: Malaria is a protozoan disease transmitted by the bite of infected female anopheles mosquitoes is one of the most important parasitic diseases of human with transmission in 109 countries, affecting more than one billion people worldwide. This study was planned to compare the gold standard i.e. peripheral blood smear examination and the newer rapid diagnostic test (malaria plasmodium falciparum/ plasmodium vivax antigen card) to know the diagnostic accuracy of Rapid Diagnostic Test (RDT) kits. Methods: All the suspected cases of WHO defined malaria between 1month to 18 years of age were enrolled in the study.Results: Out of 96 clinically suspected cases of malaria 63 were confirmed by peripheral smear. The age range of participants ranged from 4 months to 17 years. On peripheral smear examination, out of 96 clinically suspected cases, 37 (38.5%) cases were positive for P. vivax, 23 (23.9%) were positive for P. falciparum and 3 (3.1%) were positive for both parasites by microscopy. Sensitivity and specificity of RDT for Plasmodium Vivax is 92.5% and 96.4% respectively. Sensitivity and specificity of RDT for Plasmodium Falciparum is 96.2% and 90%.Conclusions: The rational use of RDTs as a complement to microscopy might give substantial health benefits through earlier treatment, reduction in morbidity and mortality and more rationalized approach for choosing anti-malarial drugs, which in terms may prevent drug resistance.

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A portfolio of geographically distinct laboratory-adapted Plasmodium falciparum clones with consistent infection rates in Anopheles mosquitoes

Malaria Journal ◽

10.1186/s12936-021-03912-x ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Marga van de Vegte-Bolmer ◽

Wouter Graumans ◽

Rianne Stoter ◽

Geert-Jan van Gemert ◽

Robert Sauerwein ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Production Capacity ◽

Infection Intensity ◽

Anopheles Coluzzii ◽

Infection Rates ◽

Malaria Research ◽

Anopheles Mosquitoes ◽

Malaria Interventions ◽

Geographical Locations

Abstract Background The ability to culture Plasmodium falciparum continuously in vitro has enabled stable access to asexual and sexual parasites for malaria research. The portfolio of isolates has remained limited and research is still largely based on NF54 and its derived clone 3D7. Since 1978, isolates were collected and cryopreserved at Radboudumc from patients presenting at the hospital. Here, procedures are described for culture adaptation of asexual parasites, cloning and production of sexual stage parasites responsible for transmission (gametocytes) and production of oocysts in Anopheles mosquitoes. This study aimed to identify new culture-adapted transmissible P. falciparum isolates, originating from distinct geographical locations. Methods Out of a collection of 121 P. falciparum isolates stored in liquid nitrogen, 21 from different geographical origin were selected for initial testing. Isolates were evaluated for their ability to be asexually cultured in vitro, their gametocyte production capacity, and consistent generation of oocysts. Results Out of 21 isolates tested, twelve were excluded from further analysis due to lack of mature gametocyte production (n = 1) or generation of satisfactory numbers of oocysts in mosquitoes (n = 11). Nine isolates fulfilled selection criteria and were cloned by limiting dilution and retested. After cloning, one isolate was excluded for not showing transmission. The remaining eight isolates transmitted to Anopheles stephensi or Anopheles coluzzii mosquitoes and were categorized into two groups with a reproducible mean oocyst infection intensity above (n = 5) or below five (n = 3). Conclusions These new P. falciparum culture-adapted isolates with reproducible transmission to Anopheles mosquitoes are a valuable addition to the malaria research tool box. They can aid in the development of malaria interventions and will be particularly useful for those studying malaria transmission.

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Distinct kinetics in antibody responses to 111 Plasmodium falciparum antigens identifies novel serological markers of recent malaria exposure

10.1101/2020.12.14.20242768 ◽

2020 ◽

Author(s):

Victor Yman ◽

James Tuju ◽

Michael T White ◽

Gathoni Kamuyu ◽

Kennedy Mwai ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Disease Burden ◽

Antibody Responses ◽

Serological Markers ◽

Limited Data ◽

Malaria Surveillance ◽

Igg Antibody ◽

Malaria Exposure ◽

C And N ◽

Antibody Kinetics

Strengthening malaria surveillance is a key intervention needed to reduce the global disease burden. Reliable serological markers of recent malaria exposure could dramatically improve current surveillance methods by allowing for accurate estimates of infection incidence from limited data. We studied the IgG antibody response to 111 Plasmodium falciparum proteins in travellers followed longitudinally after a natural malaria infection in complete absence of re-exposure. We identified a novel combination of five serological markers (GAMA, MSP1, MSPDBL1 C- and N-terminal, and PfSEA1) that detect exposure within the previous 3-months with >80% sensitivity and specificity. Using mathematical modelling, we examined the antibody kinetics and determined that responses informative of recent exposure display several distinct characteristics: rapid initial boosting and decay, less inter-individual variation in response kinetics, and minimal persistence over time. These serological exposure markers can be incorporated into routine malaria surveillance to guide efforts for malaria control and elimination.

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