Malaria in the Era of COVID-19 | EK47

Mar 16, 2021 ‐ Mar 17, 2021



Sessions

Genetic Diversity of Plasmodium falciparum Surface Protein 25, 230 and 48/45 Gene in Malaria Endemic, Mesoendemic and Epidemic Regions of Western Kenya

Genetic Diversity of Plasmodium falciparum Surface Protein 25, 230 and 48/45 Gene in Malaria Endemic, Mesoendemic and Epidemic Regions of Western Kenya
Kevin O. Ochwedo1, 2*, Daibin Zhong3, Fredrick Otieno Ariri4, Wolfgang R. Mukabana1, 2, Antony C. A. Otieno1, Sidney O. Ogolla7, Harryson Atieli2, 6, Ming-Chieh Lee3, Shirley A. Onyango2, Pauline W. Orondo2, Benyl M. Ondeto1, 2, Collince J. Omondi1, 2, Andrew K. Githeko2,7, James W. Kazura5* and Yan Guiyan3*
Author’s affiliations
1School of biological sciences, University of Nairobi.
2Sub-Saharan Africa International Centre for Excellence in Malaria Research.
3University of California, Irvine.
4School Physical and biological, Maseno University.
5Caste Western Reserve University.
6School of Public Health and Community Development, Maseno University.
7Climate and Human Health Research Unit, Centre for Global Health Research, Kenya Medical. Research Institute, Kisumu, Kenya.

Background: Transmission blocking vaccines (TBVs) are renewed hope in complementing other malaria control strategies aimed at reducing incidents and mortality rates. Leading TBV candidate such as Plasmodium falciparum surface protein 25 (Pfs25), immunogenic domain I (D1) of Pfs230 and domain III (D3) of Pfs48/45 must overcome hurdles of antigenic alterations which may render them allele-specific or ineffective. This study explored sequence variation among three genes from malaria-endemic and epidemic region of western Kenya and described drivers of the observed mutations.
Methods: A total of 220 samples collected between 2018 and 2020 from malaria-endemic (Homa Bay and Chulaimbo) and epidemic (Kisii-highland) regions in western Kenya were genotyped. A comparison of the three genes based on their sequence diversity, genetic diversity indices, variants distribution and signature of selection were inferred from sequenced Pfs25, D1 of Pfs230 and D3 of Pfs48/45 gene was also inferred.
Results: A total of 10, 6 and 2 polymorphic loci were detected across Pfs25, D1 of Pfs230 and D3 of Pfs48/45 gene respectively from malaria-endemic and epidemic region in western Kenya. Singleton variable sites and nonsynonymous changes each comprised of 60% of the observed changes in Pfs25 sequences from endemic and epidemic sites. Domain III of Pfs25 gene had the highest number (60%) mutated sites, of which all polymorphic loci were under a purifying selection. Two dimorphic loci pairs were under linkage disequilibrium whereas others (105 and 511) had a history of recombination. Nonsynonymous changes predominated all the 6 polymorphic sites with dimorphic codon G605S being pronounced in D1 of Pfs230. Apart from mutated codon K661 which was under a balancing selection the rest were under purifying selection. History of recombination was detected between sites 1813 and 1955 among the mutated sites. Two mutated sites resulting in nonsynonymous changes were observed in the D3 of Pfs48/45. The two mutations occurred in 18.75% of sequences, mutated codon L314I was pronounced across the three study sites. D3 of Pfs48/45 had a high conservation index and a low number of variants.
Conclusion: The Pfs25, D1 of Pfs230 and D3 of Pfs48/45 gene from the endemic and epidemic region in Kenya revealed varying levels of genetic diversity. Within the fusion protein, D3 of Pfs48/45 gene is highly conserved and stable as a TBV candidate with less number of variants. Purifying and balancing selection, inbreeding and recombination were predicted as the cause and drivers sustaining these variations. With the observed low nucleotide diversity, the three antigens stand a chance as formidable TBV candidates.
Keywords: Transmission blocking vaccines, Pfs25, Pfs230, Pfs48/45, Polymorphism, Selection, Linkage disequilibrium, Recombination

Speaker(s):
  • Kevin O. Ochwedo, Sub-Saharan International Centre of Excellence for Malaria Research

A looming ape-malaria pandemic iconA looming ape-malaria pandemic

Preview Available

A looming ape-malaria pandemic

About 228 million cases and 405,000 deaths due to malaria were reported by World Health Organization in 2018. Malaria in humans originated from apes. Apes harbour several other malaria parasites that can potentially spill over into humans with time. This can loom into a pandemic. There is an urgent need to protect people from malaria vectors that can transmit such parasites from infected apes. A one-time exercise of screening houses around forests, with mosquito mesh and trapping any mosquitoes that may enter houses shall be done with an extension to other areas. Research participants shall be supplied with soap and face masks to curb Covid-19 and sustainability shall be done by house-owners. Participating in the e-symposium will make my research work and University College visible to a large audience. University students, staff and the community shall be protected from infective mosquito bites because they live within Kaimosi forest.

Speaker(s):

Bio-larvicidal potential of green–synthesized nanoparticles and aqueous extract of Moringa oleifera seed extract against the malaria vector, Anopheles gambiae ss (Diptera: Culicidae)

Malaria constitutes a major public health challenge across the globe. In the context of the current COVID-19 pandemic, it is a significant threat to human health, as its symptomology is very similar to the Covid-19 infection and it is also a comorbidity of the infection. In the face of dwindling resource allocations to fight other diseases of public health importance such as malaria, HIV and TB, it therefore becomes important to innovate and develop sustainable interventions in the fight against the malaria challenge. Interventions that seek to control mosquito populations can limit disease spread considerably in endemic communities. The challenge of insecticide resistance and environmental pollution also prompt the search for novel products such as green-synthesized nanoparticles and plant- derived mosquitocidal products. In this study, the bio-efficacy of two products- Moringa-synthesized silver nanoparticle (MS-AgNPs) and Aqueous extract of Moringa oleifera seed (AEMOS) were tested at five different concentrations on Anopheles gambiae ss larval instar stages (L1-L4). Twenty mosquitoes per stage were exposed to concentrations of the different treatments with five replications for 5 days. Control medium was distilled water and mortality was recorded daily. The MS-AgNPs was characterized using UV-vis spectroscopy and Transmission Electron Microscopy (TEM). Data were evaluated using Descriptive and Probit analyses. The UV-visible absorption spectra showed broad SPR band with one peak at 384.30 nm, illustrating the presence of a homogeneous distribution of hydrosol Ag-NPs at 24-hours post reaction time. The TEM analysis revealed that the MS-AgNPs were spherical in shape with an average diameter size of 25±2nm, these observed features are characteristic of silver NPs. The results from the mosquito bioassays showed that the mosquito life stages were susceptible to the MS-AgNPs and AEMOS within 24hours. The larval mortality recorded across the stages had a dose-dependent relationship with the treatments administered with significant difference among the treatment groups (p< 0.05). Mortality ranges among the larvae in the MS-AgNPs treatment group was >75% at 24-hours post-exposure while in the AEMOS group, the mortality recorded across the laral stages was >60% at 24-hours post-exposure. In terms of effectiveness of product, the MS-AgNPs treatments were highly effective against the mosquito larvae at lower doses {with LC50 and LC95 values ranging from 9.27 (16.69) ppm - 11.29 (20.32) ppm} compared to the AEMOs treatment with LC50 and LC95 values ranging from 203.99 (367.18) ppm -122.82 (221.07) ppm. Furthermore, mortality occurred more in the larval stages exposed to the MS-AgNPs compared to those exposed to AEMOS. A study is ongoing to determine the MS-AgNPs effect on growth parameters and adult emergence with respect to its biology and possible genetic implications for interventions. The Moringa synthesized-AgNPs (MS-AgNPs) and aqueous extract (AEMOS) had larvicidal activity on the exposed Anopheles mosquitos with different level of effectiveness for both products. This study highlights the potential of green-synthesized AgNPs in the search for green, low-cost and innovative interventions for the control of malaria in the ongoing COVID-19 pandemic. Further study on the mode and mechanism of action of the nanoparticles on the mosquito is recommended.

Speaker(s):

Application of mathematical models of malaria transmission to inform national strategic planning in Nigeria

Application of mathematical models of malaria transmission to inform national strategic planning in Nigeria Ifeoma D. Ozodiegwu1, Monique Ambrose2, Beatriz Galatas3, Aadrita Nandi1, Manuela Runge1, Kamaldeen Okuneye1, Neena Parveen Dhanoa4, Ibrahim Maikore5, Perpetua Uhomoibhi5, Caitlin Bever2, Abdisalan Noor3, Jaline Gerardin1

1Department of Preventive Medicine and Institute for Global Health, Northwestern University, Chicago IL USA
2Institute for Disease Modeling, Bill and Melinda Gates Foundation, Seattle WA USA
3Global Malaria Programme, World Health Organization,
4Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL,
5National Malaria Elimination Programme, Nigeria

Nigeria is one of the 10 highest burden malaria countries in Africa, accounting for roughly a quarter of all global malaria cases and deaths. For the 2020 – 2025 National Strategic Plan, the Nigerian Malaria Elimination Program (NMEP) developed a targeted approach to intervention deployment that considered spatial heterogeneity in malaria transmission at the local government level. We created an analytical framework for predicting the impact of the NMEP’s proposed intervention strategy on malaria morbidity and mortality in each of Nigeria’s 774 local government areas (LGAs). Our framework was built on EMOD, an agent-based model of Plasmodium falciparum transmission, and incorporates survey data, routine data, and programmatic data from Nigeria. Capturing the seasonality of malaria incidence and intrinsic potential of each LGA to support transmission was not possible due to data limitations at the LGA level. We therefore clustered LGAs into 22 epidemiological archetypes using monthly rainfall, temperature suitability index, vector abundance, pre-2010 parasite prevalence, and pre-2010 vector control coverage. Routine incidence data was used to determine seasonality in each archetype. We set each LGA’s baseline malaria transmission intensity by calibrating to parasite prevalence in children under the age of five years measured in the 2010 Demographic and Health Surveys (DHS), using archetype parasite prevalence to supplement LGA-level data. Intervention coverage in the 2010-2020 period was also obtained from DHS. Effect sizes of case management, vector control, and chemoprevention were previously calibrated to field data or obtained from the literature. The resultant model was used to make attributions for historical interventions and to make subnational predictions of the impact of intervention mixes proposed by the NMEP for funding by the Global Fund. Our modeling approach illustrates how dynamic models can be applied to support strategic planning for malaria and can be adopted by other high-burden countries.

Speaker(s):

Market and Online Survey, and Efficacy of fifteen commercially available mosquito repellents in Johannesburg, South Africa.

Market and Online Survey, and Efficacy of fifteen commercially available mosquito repellents in Johannesburg, South Africa.
Authors: Dr Mustapha Halidu Aliero, Professor Robyn L. van Zyl, Professor Shelley Schmollgruber, Professor Lizette Koekemoer
Key words : Malaria, Repellents, Efficacy, Commercial and Mosquito.
Background: The current Covid-19 pandemic has confined us to live indoors, being increasing more exposed and susceptible to the endophilic malaria transmitting vectors capable of transmitting malaria between 0.3 to 22.5 days earlier than outdoor vectors. With this increased potential of being infected, the use of mosquito repellents for personal protections is essential to avoid mosquito bites. Many products are available in our communities, but not all are effective..
Aim: To undertook a survey to determine which repellents are most commonly used and to ascertain the efficacy of fifteen commonly available/used repellents in Johannesburg, South Africa.
Methods: Following ethics approval, a cross-sectional survey was conducted to determine the commonly used products used by South Africans and the information on commercially available mosquito repellents sold online or in markets was collated. From this, the repellent efficacy of fifteen products was assessed against starved female Anopheles gambiae S.S. every fifteen minutes for one hour in the WRIM laboratory. A non-contact method using a plastic-double netted dual choice test chamber was used to house the 20 mosquitoes with the volunteers’ forearms held 1-2cm from the netting. N,N-diethyl-meta-toluamide (DEET; Tabard™) was used as the control repellent. Data was captured in the REDCaP and analysed using SPSS version 26.0.
Results: From the cross-sectional survey of the 637 participants (females : males – 386 : 244), 75.2% (n=479) had used mosquito repellents in the past, with a diethyl toluamide-based product (Peaceful sleep™, 15%) being the most used, 53.8% (n=343). To date, a total of 96 products have been documented from both markets (21.9%) and online shops (71.8%). Of which, only 55.2% were approved by the South African Bureau of Standard (SABS). In the efficacy studies, the control product, 19.5% DEET (Tabard™ lotion) provided a mean protection of 99.1±0.9% for all four tested volunteers; with a slightly higher mean protection of 99.5±0.3% obtained with Medi-scabiol™ soap (citronella oil). After an hour, the three least active products were all-natural products, namely Mosquito-Patch™ (citronella), So-pure™ naturally (vanilla) and No-squito™ (neem and lemongrass oil) lotion. The Kruskal-Wallis H test revealed a statistically significant differences of mean protections among the repellent products (p=0.032); however, the Dunn post-hoc test with Bonferroni’s corrections did not show statistically significant differences between the control repellent and any of the repellent products tested.
Conclusion: This result shows that the citronella-based repellent product is effective for short-term personal protection from mosquito bites; however, DEET remains the gold standard repellent product for long-term protection. Consumers are advised to check for SABS approval for any product they intend to use to ensure optimal protection.

Speaker(s):

Welcoming Remarks iconWelcoming Remarks

Preview Available

Welcoming Remarks

Mar 16, 2021 8:00am ‐ Mar 16, 2021 8:10am

Speaker(s):

Tuesday, March 16, 2021 iconTuesday, March 16, 2021

Preview Available

Tuesday, March 16, 2021

Mar 16, 2021 8:00am ‐ Mar 16, 2021 11:30am

Organizer(s):

Keynote Address: Overcoming Complex Challenges: Malaria and COVID-19

Mar 16, 2021 8:10am ‐ Mar 16, 2021 8:30am

Speaker(s):
  • Pedro L. Alonso, MD, Director of the Global Malaria Programme, World Health Organization

Lessons from COVID for Malaria iconLessons from COVID for Malaria

Preview Available

Lessons from COVID for Malaria

Mar 16, 2021 8:30am ‐ Mar 16, 2021 8:50am

Speaker(s):

Joint Q&A with Drs. Alonso and Doe-Anderson

Mar 16, 2021 8:50am ‐ Mar 16, 2021 9:05am

Chair(s): Speaker(s):