Category Archives: Genetics

Malaria News Today 2020-10-26: Haiti, India, Malaysia, Cape Verde

Recent news and abstracts explore malaria on three continents. Genetic aspects of malaria are studied in Haiti as well in Malaysia. Use of fish to control malaria carrying mosquitoes are successful in India. The movement toward malaria elimination is examined in Cape Verde. Finally, Non-invasive diagnostic tests are recognized/rewarded by NIH. Read more by following the links below.

NIH Awards Prize to Hemex Health’s Non-Invasive Sickle Cell, Malaria, Anemia Rapid Test (“SMART”) Diagnostic Technology

Researchers from Hemex Health, Medtronic plc, Case Western Reserve University, and the University of Nebraska Medical Center’s International Foundation Against Infectious Disease in Nigeria (IFAIN) were awarded 3rd place and $100,000 in the NIH Technology Accelerator Challenge.  Code named, SMART (Sickle, Malaria, Anemia, Rapid Test), the system includes non-invasive diagnostics for sickle cell, malaria, and anemia. The project seeks to build on Hemex Health’s Gazelle® platform, which currently includes minimally invasive tests (using a drop of blood) for malaria, the detection and quantification of hemoglobin variants, as well as for total hemoglobin for anemia determination.

The non-invasive test will screen for anemia, malaria, and sickle cell disease using an optical finger sensor similar to the way blood oxygen is measured. An advantage of combining the non-invasive and minimally invasive diagnostics is, when needed, more diagnostic information and confirmation is available on the same platform. The goal is a one-minute, $0.25 non-invasive malaria, sickle cell, and anemia test. “The world desperately needs easy-to-use diagnostic technologies with the flexibility needed to meet viruses and diseases in every corner of the planet,” said Ms. White.

Controlling Mosquitoes: Ramanathapuram district inches closer to malaria-free status

Steps taken by the Ramanathapuram district administration to control mosquito breeding for the last five years has enableed the district inch closer to being declared a ‘malaria-free district, with only one malarial fever case having been reported till September, this year. Last year, the district reported 43 cases.

One of the initiatives is to bring guppy fish from the Ayyankulam tank in Tiruvannamalai district and let them into all wells and tanks of the districts in 3:1 ratio (3 familes/one male). The fish thrives, eating the mosquito larvae and eggs and the incidence of malaria came down in the district.

Updates on malaria epidemiology and profile in Cabo Verde from 2010 to 2019: the goal of elimination

Located in West Africa, Cabo Verde is an archipelago consisting of nine inhabited islands. Malaria has been endemic since the settlement of the islands during the sixteenth century and is poised to achieve malaria elimination in January 2021. The aim of this research is to characterize the trends in malaria cases from 2010 to 2019 in Cabo Verde as the country transitions from endemic transmission to elimination and prevention of reintroduction phases. All confirmed malaria cases reported to the Ministry of Health between 2010 and 2019 were extracted from the passive malaria surveillance system.

A total of 814 incident malaria cases were reported in the country between 2010 and 2019, the majority of which were Plasmodium falciparum. Cabo Verde has made substantial gains in reducing malaria burden in the country over the past decade and are poised to achieve elimination in 2021. However, the high mobility between the islands and continental Africa, where malaria is still highly endemic, means there is a constant risk of malaria reintroduction. Characterization of imported cases provides useful insight for programme and enables better evidence-based decision-making to ensure malaria elimination can be sustained.

Genetic analysis reveals unique characteristics of Plasmodium falciparum parasite populations in Haiti

With increasing interest in eliminating malaria from the Caribbean region, Haiti is one of the two countries on the island of Hispaniola with continued malaria transmission. While the Haitian population remains at risk for malaria, there are a limited number of cases annually, making conventional epidemiological measures such as case incidence and prevalence of potentially limited value for fine-scale resolution of transmission patterns and trends. In this context, genetic signatures may be useful for the identification and characterization of the Plasmodium falciparum parasite population in order to identify foci of transmission, detect outbreaks, and track parasite movement to potentially inform malaria control and elimination strategies.

This study evaluated the genetic signals based on analysis of 21 single-nucleotide polymorphisms (SNPs) from 462 monogenomic (single-genome) P. falciparum DNA samples extracted from dried blood spots collected from malaria-positive patients reporting to health facilities in three southwestern Haitian departments (Nippes, Grand’Anse, and Sud) in 2016.

437 of the 462 samples shared high levels of genetic similarity–at least 20 of 21 SNPS–with at least one other sample in the dataset. These results revealed patterns of relatedness suggestive of the repeated recombination of a limited number of founding parasite types without significant outcrossing. These genetic signals offer clues to the underlying relatedness of parasite populations and may be useful for the identification of the foci of transmission and tracking of parasite movement in Haiti for malaria elimination.

Epidemiology of malaria among pregnant women during their first antenatal clinic visit in the middle belt of Ghana

A total of 1655 pregnant Ghanaian women aged 18 years and above with a gestational age of 13–22 weeks, who attended an antenatal care (ANC) clinic for the first time, were consented and enrolled into the study. A structured questionnaire was used to collect socio-demographic and obstetric data and information on use of malaria preventive measures. Venous blood (2 mL) was collected before sulfadoxine-pyrimethamine administration. Malaria parasitaemia and haemoglobin concentration were determined using microscopy and an automated haematology analyser, respectively.

One out of five pregnant women attending their first ANC clinic visit in an area of perennial malaria transmission in the middle belt of Ghana had Plasmodium falciparum infection. Age???25 years, multigravid, educated to high school level or above, and in household with higher socio-economic status were associated with a lower risk of malaria parasitaemia. Majority of the infections were below 1000 parasites/µL and with associated anaemia. There is a need to strengthen existing malaria prevention strategies to prevent unfavourable maternal and fetal birth outcomes in this population.

Genetic diversity of circumsporozoite protein in Plasmodium knowlesi isolates from Malaysian Borneo and Peninsular Malaysia

Understanding the genetic diversity of candidate genes for malaria vaccines such as circumsporozoite protein (csp) may enhance the development of vaccines for treating Plasmodium knowlesi. Hence, the aim of this study is to investigate the genetic diversity of non-repeat regions of csp in P. knowlesi from Malaysian Borneo and Peninsular Malaysia.
The phylogenetic analysis revealed indistinguishable clusters of P. knowlesi isolates across different geographic regions, including Malaysian Borneo and Peninsular Malaysia.

The csp non-repeat regions are relatively conserved and there is no distinct cluster of P. knowlesi isolates from Malaysian Borneo and Peninsular Malaysia. Distinctive variation data obtained in the C-terminal non-repeat region of csp could be beneficial for the design and development of vaccines to treat P. knowlesi.

Malaria News Today 2020-09-30: Diagnostics, Mosquito Genes and Neutrophils

Mosquito populations vary across nations and can be spurred by change in land use and deforestation as seen in Madagascar. Urine and saliva have potential in diagnostics but have lower sensitivity than blood tests. Not all insects have similar genes, and mosquitoes evolved a different gene to handle body segmentation. The DHS Program has released recent Malaria Indicator Surveys for Ghana and Uganda, but indicators are below targets. The emerging roles for neutrophils in malaria will be discussed at a webinar. Finally cost-effectiveness issues around RDTs is noted. More information can be obtained via the hyperlinks.

Variation in Anopheles distribution and predictors of malaria infection risk across regions of Madagascar

Deforestation and land use change is widespread in Madagascar, altering local ecosystems and creating opportunities for disease vectors, such as the Anopheles mosquito, to proliferate and more easily reach vulnerable, rural populations. Knowledge of risk factors associated with malaria infections is growing globally, but these associations remain understudied across Madagascar’s diverse ecosystems experiencing rapid environmental change. This study aims to uncover socioeconomic, demographic, and ecological risk factors for malaria infection across regions through analysis of a large, cross-sectional dataset.

The presence of aquatic agriculture (both within and surrounding communities) is the strongest predictive factor of habitats containing Anopheles larvae across all regions. Ecological and socioeconomic risk factors for malaria infection vary dramatically across study regions and range in their complexity. Risk factors for malaria transmission differ dramatically across regions of Madagascar. These results may help stratifying current malaria control efforts in Madagascar beyond the scope of existing interventions.

Evaluating the potential of using urine and saliva specimens for malaria diagnosis in suspected patients in Ghana

This study aimed at detecting PfHRP2 and pLDH malaria antigens in urine and salivary specimens of suspected malaria patients using RDT kits, and identifying factors influencing the detection of these antigens. Malaria rapid test kit (SD Bioline RDT kit) was used to detect malaria antigens, PfHRP2 and pLDH, in blood, urine and saliva samples received from patients suspected of malaria. Subsequently, malaria parasitaemia was determined.

A total of 706 suspected malaria patients provided all three specimens. Prevalence of malaria by microscopy and RDT was 44.2% and 53.9%, respectively. Compared to blood, the sensitivities of urine and saliva were 35.2% and 57.0% respectively. Haemoglobin concentration?<?9.9 g/dL, body temperature?>?38.7 °C and occult blood influenced the detection of malaria antigens in both urine and saliva. Furthermore, the antigens were not detected in urine and saliva when parasitaemia was?<?60,000 parasites/µL and?<?40,000 parasites/µL, respectively.

Saliva, with or without blood contamination, was found to be more efficient that urine samples. Therefore these non-blood specimens have the potential to be used as non-invasive samples for malaria diagnosis. However, this approach is useful in severe to moderate anaemia, hyperthermia, parasitaemia?>?60,000 parasites/µL and samples contaminated with blood.

Mosquitos lost an essential gene for body segmentation with no ill effects

University of Maryland entomologists discovered that a gene critical for survival in other insects is missing in mosquitoes—the gene responsible for properly arranging the insects’ segmented bodies. The researchers also found that a related gene evolved to take over the missing gene’s job. Although laboratory studies have shown that similar genes can be engineered to substitute for one another, this is the first time that scientists identified a gene that naturally evolved to perform the same critical function as a related gene long after the two genes diverged down different evolutionary paths.

The work emphasizes the importance of caution in genetic studies that use model animals to make conclusions across different species. It also points to a new potential avenue for research into highly targeted mosquito control strategies. The research study was published in the September 30, 2020, issue of the journal Communications Biology. “Every single arthropod has a segmented body plan. And you would think it develops the same way in all of them. But what we found is that it doesn’t,” said Alys Jarvela. “That means different genes probably regulate male fertility in mosquitoes, and they might be unique to the mosquito, which could potentially provide a powerful avenue for controlling mosquitoes without harming other insects such as butterflies and bees,” Jarvela said.

Two New Malaria Indicator Surveys Available

Ghana 2019 MIS/DHS Infographic. Malaria prevalence going down from 27% in 2014 to 14% in 2019. Still below target in terms of ITN coverage of and in households.

Uganda 2018-19 MIS/DHS Infographic.  Wide regional variation in malaria prevalence from 1-5% in the southwest to 34% in the northeast. ITN use by children and pregnant women below 2/3rds, while only 2/5 pregnant women got 3 doses of IPT.

Emerging Roles for Neutrophils in Malaria

Aubrey Cunnington and an interdisciplinary translational research group studying host-pathogen interactions in severe infections, focussing on malaria in particular. See for example,  “A More Granular View of Neutrophils in Malaria

Neutrophils are abundant innate immune cells with crucial roles in immunity and vascular inflammation. Recent evidence indicates that neutrophils have a dual role in malaria, contributing to both pathogenesis and control of Plasmodium. We discuss emerging mechanisms behind these opposing functions and identify key outstanding questions.

Cost-effectiveness analysis of malaria rapid diagnostic test in the elimination setting

As more and more countries approaching the goal of malaria elimination, malaria rapid diagnostic tests (RDT) was recomended to be a diagnostic strategy to achieve and maintain the statute of malaria free, as it’s less requirements on equipment and expertise than microscopic examination. But there are very few economic evaluations to confirm whether RDT was cost-effective in the setting of malaria elimination. This research aimed to offer evidence for helping decision making on malaria diagnosis strategy.

The results showed that RDT strategy was the most effective (245 cases) but also the most costly (United States Dollar [USD] 4.47 million) compared to using microscopy alone (238 cases, USD 3.63 million), and RDT followed by microscopy (221 cases, USD 2.75 million). There was no strategy dominated. One-way sensitivity analysis reflected that the result was sensitive to the change in labor cost and two-way sensitivity analysis indicated that the result was not sensitive to the proportion of falciparum malaria. The result of Monte Carlo simulation showed that RDT strategy had higher effects and higher cost than other strategies with a high probability. Compared to microscopy and RDT followed by microscopy, RDT strategy had higher effects and higher cost in the setting of malaria elimination.