elimination in Lake Victoria, Kenya
Scientists sequenced Plasmodium falciparum genomes to better understand malaria parasite populations and track drug resistance biomarkers in and around Lake Victoria, Kenya

Date:
November 16, 2021
Source:
Osaka City University
Summary:
Scientists are turning to genomics to better understand the
epidemiology of malaria and to inform control and elimination
interventions and strategies. In the Lake Victoria region of Kenya,
malaria burden remains very high despite more than a decade of
intense control activities. A team of researchers generated whole
Plasmodium falciparum genome sequences from the lake region. Their
analyses revealed that malaria parasites from this region appear
distinct from other parasites from East Africa, while frequencies
of known drug resistance markers were similar to those in other
East African parasite populations.



FULL STORY ========================================================================== Since 2016, progress in reducing malaria-related incidence and deaths over
the past decade has been slowing down. On top of this, restrictions put
in place to contain the COVID-19 pandemic have further limited malaria
control programs such as mass bed net distribution and indoor residual
spraying campaigns. To regain the momentum toward malaria elimination, scientists have increasingly turned to malaria parasite genomics to get
a better understanding of the epidemiology and transmission dynamics,
and the genetic basis underlying drug resistance and disease severity.


==========================================================================
"A comprehensive picture of a population of parasites requires an
understanding of them on the individual genome level," says Professor
Akira Kaneko of the Department of Parasitology, Osaka City University
Graduate School of Medicine.

For the past decade, Professor Kaneko and his collaborators have conducted various studies on malaria in and around Lake Victoria, Kenya, where
the disease burden is among the highest in the country, to find ways to eliminate malaria successfully. To gain more insights into the genomic diversity and population dynamics of Plasmodium falciparum, the deadliest malaria parasite in humans, Kaneko and his collaborators generated whole
genome sequence data from 48 parasite isolates and compared them with
parasites from other parts of Africa. They described their findings in
the journal Scientific Reports.

Analyses based on single nucleotide polymorphisms (SNPs) or point
mutations showed that P. falciparum parasites from Lake Victoria formed a distinct subpopulation within the larger East African parasite population, caused in part by the greater contribution of Central African parasites
to the ancestral genomes of Lake Victoria parasites. Moreover, the team identified a number of SNPs that can potentially be used in a molecular surveillance tool to determine the main routes of transmission and
migration of P. falciparum. "The population-specific SNPs we identified
provide a high degree of small-scale specificity, typically to the
country of origin, "states Professor Kaneko.

"Combine these with the wider regional or continental view gained from population-specific organellar SNPs, and we could have the degree of
resolution needed to generate an effective molecular surveillance tool." Another important piece to the picture were the drug resistance markers
that the team observed circulating among P. falciparum isolates around
Lake Victoria. They saw the persistence of the main resistance marker for
the drug chloroquine, as well as high frequencies of mutations associated
with sulfadoxine-pyrimethamine (SP) resistance. The team believed that the continued use of SP as intermittent preventative treatment by pregnant
women (IPTp) is likely providing enough selective pressure to maintain
these polymorphisms in P. falciparum.

"We are especially excited about the potential application of the data we
found regarding variations of P. falciparum and known drug resistance biomarkers we observed in parasite isolates from the area," says
Dr. Wataru Kagaya, Medical Lecturer of the Department of Parasitology,
Osaka City University Graduate School of Medicine. One in particular
stood out. They confirmed the presence of the S160N/T mutation in the
gene Pfap2mu, which was first documented in Kenyan children with delayed parasite clearance when treated with artemisinin-based combination
therapies (ACTs), currently the first-line treatment for uncomplicated
malaria. "Our work is expected to assist in the clinical management and
disease control through surveillance activities in regions with high
malaria burden," adds Kagaya.

========================================================================== Story Source: Materials provided by Osaka_City_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Ashley Osborne, Emilia Manko, Mika Takeda, Akira Kaneko, Wataru
Kagaya,
Chim Chan, Mtakai Ngara, James Kongere, Kiyoshi Kita,
Susana Campino, Osamu Kaneko, Jesse Gitaka, Taane
G. Clark. Characterizing the genomic variation and population
dynamics of Plasmodium falciparum malaria parasites in and
around Lake Victoria, Kenya. Scientific Reports, 2021; 11 (1)
DOI: 10.1038/s41598-021-99192-1 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211116103129.htm

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