Journal of Infection and Public Health, May 1, 2016
Since its discovery in 1947 in Uganda and control and eradication efforts have aimed at its vecto... more Since its discovery in 1947 in Uganda and control and eradication efforts have aimed at its vectors (Aedes mosquitoes) in Latin America in the 1950s, an absolute neglect of Zika programs and interventions has been documented in Aedes endemic and epidemic-prone countries. The current unprecedented Zika viral epidemics and rapid spread in the Western hemisphere pose a substantial global threat, with associated anxiety and consequences. The lack of safe and effective drugs and vaccines against Zika or dengue epidemics further buttresses the realization from the West Africa Ebola outbreak that most emerging disease-prone countries are still poorly prepared for an emergency response. This paper examines knowledge gaps in both emerging and neglected arthropod-borne flavivirus infectious diseases associated with poverty and their implications for fostering local, national and regional emerging disease preparedness, effective and robust surveillance-response systems, sustained control and eventual elimination. Strengthening the regional and Global Health Flavivirus Surveillance-Response Network (GHFV-SRN) with other models of socio-economic, climatic, environmental and ecological mitigation and
During mosquito transmission, malaria ookinetes must cross a chitin-containing structure known as... more During mosquito transmission, malaria ookinetes must cross a chitin-containing structure known as the peritrophic matrix (PM), which surrounds the infected blood meal in the mosquito midgut. In turn, ookinetes produce multiple chitinase activities presumably aimed at disrupting this physical barrier to allow ookinete invasion of the midgut epithelium. Plasmodium chitinase activities are demonstrated targets for human and avian malaria transmission blockade with the chitinase inhibitor allosamidin. Here, we identify and characterize the first chitinase gene of a rodent malaria parasite, Plasmodium berghei. We show that the gene, named PbCHT1, is a structural ortholog of PgCHT1 of the avian malaria parasite Plasmodium gallinaceum and a paralog of PfCHT1 of the human malaria parasite Plasmodium falciparum. Targeted disruption of PbCHT1 reduced parasite infectivity in Anopheles stephensi mosquitoes by up to 90%. Reductions in infectivity were also observed in ookinete feeds-an artificial situation where midgut invasion occurs before PM formationsuggesting that PbCHT1 plays a role other than PM disruption. PbCHT1 null mutants had no residual ookinete-derived chitinase activity in vitro, suggesting that P. berghei ookinetes express only one chitinase gene. Moreover, PbCHT1 activity appeared insensitive to allosamidin inhibition, an observation that raises questions about the use of allosamidin and components like it as potential malaria transmission-blocking drugs. Taken together, these findings suggest a fundamental divergence among rodent, avian, and human malaria parasite chitinases, with implications for the evolution of Plasmodium-mosquito interactions.
Membrane skeletons are cytoskeletal elements that have important roles in cell development, shape... more Membrane skeletons are cytoskeletal elements that have important roles in cell development, shape, and structural integrity. Malaria parasites encode a conserved family of putative membrane skeleton proteins related to articulins. One member, IMC1a, is expressed in sporozoites and localizes to the pellicle, a unique membrane complex believed to form a scaffold onto which the ligands and glideosome are arranged to mediate parasite motility and invasion. IMC1b is a closely related structural paralogue of IMC1a, fostering speculation that it could be functionally homologous but in a different invasive life stage. Here we have generated genetically modified parasites that express IMC1b tagged with green fluorescent protein, and we show that it is targeted exclusively to the pellicle of ookinetes. We also show that IMC1b-deficient ookinetes display abnormal cell shape, reduced gliding motility, decreased mechanical strength, and reduced infectivity. These findings are consistent with a membrane skeletal role of IMC1b and provide strong experimental support for the view that membrane skeletons form an integral part of the pellicle of apicomplexan zoites and function to provide rigidity to the pellicular membrane complex. The similarities observed between the loss-of-function phenotypes of IMC1a and IMC1b show that membrane skeletons of ookinetes and sporozoites function in an overall similar way. However, the fact that ookinetes and sporozoites do not use the same IMC1 protein implies that different mechanical properties are required of their respective membrane skeletons, likely reflecting the distinct environments in which these life stages must operate.
embrane skeletons are structural elements that provide mechanical support to the plasma membrane ... more embrane skeletons are structural elements that provide mechanical support to the plasma membrane and define cell shape. Here, we identify and characterize a putative protein component of the membrane skeleton of the malaria parasite. The protein, named PbIMC1a, is the structural orthologue of the Toxoplasma gondii inner membrane complex protein 1 (TgIMC1), a component of the membrane skeleton in tachyzoites. Using targeted gene disruption in the rodent malaria species Plasmodium berghei , we show that M PbIMC1a is involved in sporozoite development, is necessary for providing normal sporozoite cell shape and mechanical stability, and is essential for sporozoite infectivity in insect and vertebrate hosts. Knockout of PbIMC1a protein expression reduces, but does not abolish, sporozoite gliding locomotion. We identify a family of proteins related to PbIMC1a in Plasmodium and other apicomplexan parasites. These results provide new functional insight in the role of membrane skeletons in apicomplexan parasite biology. We used BLAST homology searches with the TgIMC1 amino acid sequence to identify orthologous genes in Plasmodium . The
Frontiers in Cellular and Infection Microbiology, Feb 10, 2023
Emerging mosquito-borne diseases and novel biocontrol strategies Mosquito-borne diseases threaten... more Emerging mosquito-borne diseases and novel biocontrol strategies Mosquito-borne diseases threaten more than 40% of the world's population and are an increasingly serious global health challenge . A report released by the World Health Organization (WHO) showed that malaria caused 247 million cases and 619,000 deaths in 2021, and there is no significant progress in current malaria control (World Health Organization, 2023a). The global incidence and number of reported epidemic areas of dengue have also grown dramatically (World Health Organization, 2023). Moreover, Zika, a newly emerged mosquito-borne disease associated with neurological complications, has recently caused several large outbreaks involving 89 countries and territories (World Health Organization, 2023b). Furthermore, no efficient vaccines or drugs for diseases such as dengue and Zika are publicly available, and vector control remains largely dependent on traditional insecticide-based strategies . Notably, the limitation of the current vector control effect is partly due to the overreliance on chemical control . Chemical insecticides used to be the primary strategy for mosquito control, but insecticide resistance has widely emerged in mosquitoes in recent years (World Health Organization, 2018; Peng et al., 2022). Extensive use of insecticides both in mosquito control and agriculture led to environmental pollution and exerted effects on non-targeted organisms (Deng et al., 2019). Thus, there is a growing need for more sustainable, environmentally friendly, and low-cost vector control strategies that can be implemented on a large scale to harness insecticide-resistant mosquitoes and reduce mosquito-borne disease burden. Biological control agents are important alternatives or complements to chemical insecticides. Combined with genetic approaches (e.g., transgenesis and paratransgenesis) and other biological rear and release theories, novel approaches, including entomopathogenic fungi (Metarhizium anisopliae and Beauveria bassiana) (Deng et al., 2019; Peng et al., 2022), symbiotic bacteria (Wolbachia) , lethal bacteria (Bacillus thuringiensis) Frontiers in Cellular and Infection Microbiology frontiersin.org 01
Hard ticks are causative agents of physical illness and vectors of important diseases of human an... more Hard ticks are causative agents of physical illness and vectors of important diseases of human and livestock. The hard tick Hyalomma dromedarii Koch, 1844 is a major ectoparasite of livestock in the Kingdom of Saudi Arabia (KSA), of which, the onehumped dromedaries Camelus dromedarius is the most economically and culturally important and a potential reservoir of Middle East respiratory syndrome coronavirus (MERSCoV) disease. Here we report on the molecular phylogenetic diversity of H. dromedarii collected from camels in the Eastern Province of KSA based on the mitochondrial cytochrome oxidase I (COI) gene. Maximum likelihood (ML) phylogenetic analysis of COI sequences of the studied ticks identified 11 haplotypes. All H. dromedarii ticks from KSA belonged to eight haplotypes diverged into two distinguished genetic clades (A-B). These results indicate that H. dromedarii ticks from KSA are monophyletic species with two distinguished lineages with low intra-specific genetic divergence and sharply structured isolated populations with high level of genetic differentiation. This is a first report of DNA barcode of H. dromedarii ticks from KSA and the Arabian Peninsula, which is an important step towards broader phylogenetic studies on larger tick samples from the region. The studies are important for better understanding its interactions with camels and other hosts and role in zoonotic disease transmission (e.g. MERS-CoV or Alkhurma virus) to pinpoint effective control strategies.
A novel rotator trap was evaluated to determine the diel activity patterns and physiological stat... more A novel rotator trap was evaluated to determine the diel activity patterns and physiological state of adult female mosquitoes in St. Augustine, FL, U.S.A. Culex nigripalpus were most active from 19:00-21:00, followed by 1:00-3:00, based on collections from the novel rotator trap. Furthermore, analysis of the physiological state of female mosquitoes collected by the novel rotator trap suggested that non-parous (nulliparous) host-seeking mosquitoes were more frequently active in the 21:00-23:00 and 09:00-19:00 time frames. Parous host-seeking mosquitoes were more frequently collected from 19:00-21:00 and 1:00-3:00. A low abundance of gravid females was collected by the rotator trap, so analysis of their activity periods was inconclusive. These results indicate that the novel rotated trap could be used to detect the diel activity patterns of adult mosquitoes in mosquito control programs and more testing should be conducted in the future.
Transactions of The Royal Society of Tropical Medicine and Hygiene, Apr 1, 2012
Sand fly salivary fluid contains numerous proteins that modulate host immune responses to infecti... more Sand fly salivary fluid contains numerous proteins that modulate host immune responses to infection and facilitate blood-feeding and establishing Leishmania infection. Salivary proteins are differentially expressed in adaptation to the host, the meal type and ecological factors. We report on the morphometrics and protein composition of salivary glands of colonised Phlebotomus papatasi and P. langeroni sand flies from Egypt. Female glands were dissected at day 1 (D1, unfed), day 2 (D2, sugar-fed), day 3 (D3, blood-fed) and day 7 (D7, blood-digested). The salivary glands are composed of two lobes: heterogeneous in P. papatasi and homogeneous in P. langeroni. Lobe sizes varied considerably with fly age and feeding state; D3 flies had the largest lobe sizes and protein content. The P. papatasi flies had larger lobes and higher protein content than the P. langeroni flies. The P. papatasi D1 flies had 15 protein bands that decreased in the D2, D3 and D7 flies to 10 bands in the Sinai flies and 9 bands in the Alexandria flies. All P. langeroni flies had 12 protein bands but with different intensities. The results reveal inter-specific variation between P. papatasi and P. langeroni, while no intra-specific variation between P. papatasi strains. These results increase our understanding of salivary gland protein composition and blood-feeding behaviour in Old World sand flies with implications for leishmaniasis epidemiology and control.
Journal of Infection and Public Health, May 1, 2020
Increasing emergence and spread of Nipah, ZIKV and Ebola case and potential outbreaks threats hav... more Increasing emergence and spread of Nipah, ZIKV and Ebola case and potential outbreaks threats have been reported in several regions around the globe. Yet, emerging Nipah, Ebola and Zika viral diseases outbreaks have been indirectly linked to substantially globalization of trade and travel, climate change and intense urbanization impact, healthcare and socioeconomic inequities as well in affected community settings. Although no case has been documented in Saudi Arabia, there is a great risk of sudden emergence of any of these viruses and others via introducing among pilgrims coming from endemic regions during ritual ceremonies of mass gatherings. Consequently, promoting and investing on new and sensitive proven effective and innovative surveillance and monitoring approaches, including enhanced risk communication, improved integrated vectors surveillance in addition to improved sustainable highly pathogens surveillance control programs to human motility and environmental sanitation strategies all represent 'One Health' approach implementation strategic core. Initiation, development and implementation leaded by Saudi government and international stakeholders' of new partnership, coordinated response leadership and resource mobilization for multidisciplinary and intersectorial advocacy on emerging viral disease outbreaks, accompanied with R&D roadmap and taskforce is crucial. More efforts in epidemiological and laboratory early screening and surveillance of highly pathogenic germs/microbes, and confirmation of asymptomatic and syndromic cases amongst suspected Hajj and Umrah pilgrims, local vulnerable populations and expatriate workers is vital in generating reliable data and data sharing platform for timely risk communication and tourist information update, appropriate immunization campaigns or safe and efficacious care delivery implementation. Moreover, increase Hajj/Umrah mass gathering emergency outbreak preparedness, pilgrims health education and engagement outreach, pre-, during and post programs coverage and effectiveness is needed through One Health approach integration in attaining pilgrims and local population health safety and security, in advancing Saudi sustainable health development goals.
Journal of the Egyptian Society of Parasitology, Apr 1, 2010
Medicinal plants have long history as important components in traditional medicine, and food of h... more Medicinal plants have long history as important components in traditional medicine, and food of humans since ancient Egyptians and Chinese. Naturally occurring botanical compounds contain a broad range of chemical active ingredients can intervene in all biological processes of the mosquito, thus interrupt its life cycle and dispersal and reduce harms to humans and animals. Many medicinal plants were tested for their pesticide and repellent potential, as crude material, essential oils or individual active ingredients. This article reviewed studies on the efficacy of many well known and commonly used safe medicinal plants or their products in controlling the mosquitoes; Aedes aegypti, Anopheles gambiae, An. stephensi and Culex quinquefasciatus and the ticks, Dermacentor variabilis, Amblyomma americanum, Ixodes scapularis and I. ricinus. Promising and encouraging results were obtained against these arthropod-vectors of zoonotic diseases.
There are at least five common mosquito-borne viruses (MBVs) recorded in Egypt, including dengue ... more There are at least five common mosquito-borne viruses (MBVs) recorded in Egypt, including dengue virus (DENV), Rift Valley fever virus (RVFV), West Nile virus (WNV), Chikungunya virus, and Sindbis virus. Unexpected outbreaks caused by MBVs reflect the deficiencies of the MBV surveillance system in Egypt. This systematic review characterized the epidemiology of MBV prevalence in Egypt. Human, animal, and vector prevalence studies on MBVs in Egypt were retrieved from Web of Science, PubMed, and Bing Scholar, and 33 eligible studies were included for further analyses. The monophyletic characterization of the RVFV and WNV strains found in Egypt, which spans about half a century, suggests that both RVFV and WNV are widely transmitted in this nation. Moreover, the seropositive rates of DENV and WNV in hosts were on the rise in recent years, and spillover events of DENV and WNV to other countries from Egypt have been recorded. The common drawback for surveillance of MBVs in Egypt is the la...
With over 72 countries and territories affected worldwide with Aedes mosquito-transmitted Zika vi... more With over 72 countries and territories affected worldwide with Aedes mosquito-transmitted Zika virus disease and estimated over millions of people are at high ZIKV risk including pregnant women in these Aedes mosquito-prone settings. The recent epidemic events further stress the everincreasing need and value of national public health evidence-based decision-making policy, budget allocation and programs in protecting vulnerable communities. This paper highlights Aedes vector ecological determinants and impacts mitigation and adaptation approaches in strengthening and in scaling-up integrated Aedes mosquito management programs and ZIKV epidemics prevention and containment measures across Aedes-prone African countries. The paper advocates for the urgency to establish and strengthen effective and robust local and national public health laboratories surveillance and inter-sectorial monitoring capabilities in scaling-up evidence-based and integrated Aedes vector management programs and Zi...
Susceptibility status of Ae. albopictus and Ae. aegypti was evaluated in different localities of ... more Susceptibility status of Ae. albopictus and Ae. aegypti was evaluated in different localities of four towns namely Samanabad, Nishtar, Ravi and Iqbal town in Lahore district, Eastern Punjab, Pakistan. Susceptibility test using WHO test kits was applied on adult females (12-24) hrs. Post emergence (nonblood fed) live mosquitoes under laboratory conditions at 27-29 0C temperature and 85-95% humidity. Ae. aegypti and Ae. Albopictus were found resistant to 4% DDT with < 36.28% mortality. Both species were also found resistant against 0.05% deltamethrin, 0.05%, lambdacyhalothrin and 0.75% permethrin at all localities with <75.00%, <87.00% and <81.05% mortalities respectively. Ae. albopictus was found resistant to 0.1% bendiocarb at Samanabad and Iqbal towns, while resistance possible to be confirmed at Nishtar and Ravi towns. Ae. aegypti found susceptible to 0.1% bendiocarb at Samanabad town, resistant at Ravi town and resistance possible to be confirmed (incipient) at Nishta...
Gene mutations on target sites can be a valuable indicator of the status of insecticide resistanc... more Gene mutations on target sites can be a valuable indicator of the status of insecticide resistance. Jeddah, a global commercial and major port-of-entry city, is bearing the brunt of dengue disease burden in Saudi Arabia. In the current study, six genotypes of three codon combinations (989, 1016, and 1534) were observed on voltage-gated sodium channel (VGSC) gene in Jeddah’s Aedes aegypti population, with PGF/PGC as the dominant one. Two types of introns between exon 20 and 21 on VGSC have been identified for the first time in Ae. aegypti in Saudi Arabia. Statistical and phylogenetic analyses showed that the intron type was significantly associated with the 1016 allele and may reflect the history of insecticide treatment in different continents. In addition, fixation of the L1014F allele on VGSC and G119S on acetylcholinesterase 1 gene was detected in local Culex quinquefasciatus populations, with frequencies of 95.24 and 100%, respectively. To the best of our knowledge, this is the ...
A novel rotator trap was evaluated to determine the diel activity patterns and physiological stat... more A novel rotator trap was evaluated to determine the diel activity patterns and physiological state of adult female mosquitoes in St. Augustine, FL, U.S.A. Culex nigripalpus were most active from 19:00-21:00, followed by 1:00-3:00, based on collections from the novel rotator trap. Furthermore, analysis of the physiological state of female mosquitoes collected by the novel rotator trap suggested that non-parous (nulliparous) host-seeking mosquitoes were more frequently active in the 21:00-23:00 and 09:00-19:00 time frames. Parous host-seeking mosquitoes were more frequently collected from 19:00-21:00 and 1:00-3:00. A low abundance of gravid females was collected by the rotator trap, so analysis of their activity periods was inconclusive. These results indicate that the novel rotated trap could be used to detect the diel activity patterns of adult mosquitoes in mosquito control programs and more testing should be conducted in the future.
Africa being part of the global village is challenged by unprecedented and persistent emerging in... more Africa being part of the global village is challenged by unprecedented and persistent emerging infectious diseases threats and outbreaks. Recent memories of the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) outbreaks in Saudi Arabia (2012) and South Korea (2015), West Africa Ebola viral disease outbreak and public health humanitarian crisis (2014) and China's SARS outbreaks. Various differences and similarities between these diseases have triggered serious concerns and magnified that similar outbreaks could occur anywhere in the world with lingering health complications, socio-political and economic crises. Yet, there is dearth of knowledge on MERS-CoV reservoirs, risk factors of emergence, infectivity and transmissibility in Africa and globally. This paper highlights forward approaches and key activities to the African Union, governments and institutions and all stakeholders including public-private partnership. These play paramount roles in providing information and support to address MERS-CoV and other emerging infectious diseases research gaps, (2) promoting community alertness and resilience in preparedness, (3) fostering effective and coordinated logistics in risk communication, planning and response in MERS-CoV public mobilization literacy and awareness, advocacy and mitigation. There is an urgent need to establish an integrated and strategic evidence-based local and nationwide surveillance and response capacity, (5) better understand the MERS-CoV animal reservoir(s) and human-human infectivity and transmissibility, and (6) implement informed community-based or national threat and epidemics actionable emergency insurance facility and compensation schemes. Conclusively, improved early warning, active and integrated epidemiological and genomic surveillance indicators data gathering to inform and guide effective and community resilience capability in consolidating and upholding knowledge gains from "One Health Surveillance Network" and best practices in achieving "One Health" and global health security.
Dengue is still a substantial vector-borne viral disease threat and burden of public health impor... more Dengue is still a substantial vector-borne viral disease threat and burden of public health importance worldwide. This situation is complicated by dengue virus unprecedented resurgence and persistence of varied serotypes in endemic-prone areas, and man-made and natural activities consequences that promote vector emergence, transmission dynamics and spread across the Asia-Pacific region. There is an urgent need to strengthen operational and contextual surveillance-response research in improving early detection of active reservoir detection, novel drug in case management and quality evidence-based response including the deployment of dengue mass vaccination. Moreover, sustained mapping and watching of dengue risk factors or determinants, performance and outcome indicators of control or elimination programs effectiveness in defining minimum effective data towards community knowledge-based decision-making policy and effective response packages is imperative. Moreover, implementation of a robust, integrated dengue early warning surveillance, monitoring and response systems metrics is required for evidence-based, timely and cost-effective contextual mitigation strategies, and innovative interventions.
Since its discovery in 1947 in Uganda and control and eradication efforts have aimed at its vecto... more Since its discovery in 1947 in Uganda and control and eradication efforts have aimed at its vectors (Aedes mosquitoes) in Latin America in the 1950s, an absolute neglect of Zika programs and interventions has been documented in Aedes endemic and epidemic-prone countries. The current unprecedented Zika viral epidemics and rapid spread in the Western hemisphere pose a substantial global threat, with associated anxiety and consequences. The lack of safe and effective drugs and vaccines against Zika or dengue epidemics further buttresses the realization from the West Africa Ebola outbreak that most emerging disease-prone countries are still poorly prepared for an emergency response. This paper examines knowledge gaps in both emerging and neglected arthropod-borne flavivirus infectious diseases associated with poverty and their implications for fostering local, national and regional emerging disease preparedness, effective and robust surveillance-response systems, sustained control and eventual elimination. Strengthening the regional and Global Health Flavivirus Surveillance-Response Network (GHFV-SRN) with other models of socio-economic, climatic, environmental and ecological mitigation and
The Millennium Development Goals (MDGs) made a marked transformation for neglected and vulnerable... more The Millennium Development Goals (MDGs) made a marked transformation for neglected and vulnerable communities in the developing countries from the start, but infectious diseases of poverty (IDoPs) continue to inflict a disproportionate global public health burden with associated consequences, thereby contributing to the vicious cycle of poverty and inequity. However, the effectiveness and large-scale coverage of artemisinin combination therapy (ACT) have revolutionized malaria treatment just as the control of lymphatic filariasis (LF) and onchocerciasis have benefitted from harnessing the broad-spectrum effect of avermectin-based derivatives. The paradigm shift in therapeutic approach, effected by these two drugs and their impact on community-based interventions of parasitic diseases plaguing the endemic low- and middle-income countries (LIMCs), led to the Nobel Prize in Physiology or Medicine in 2015. However, the story would not be complete without mentioning praziquantel. The hug...
Journal of Infection and Public Health, May 1, 2016
Since its discovery in 1947 in Uganda and control and eradication efforts have aimed at its vecto... more Since its discovery in 1947 in Uganda and control and eradication efforts have aimed at its vectors (Aedes mosquitoes) in Latin America in the 1950s, an absolute neglect of Zika programs and interventions has been documented in Aedes endemic and epidemic-prone countries. The current unprecedented Zika viral epidemics and rapid spread in the Western hemisphere pose a substantial global threat, with associated anxiety and consequences. The lack of safe and effective drugs and vaccines against Zika or dengue epidemics further buttresses the realization from the West Africa Ebola outbreak that most emerging disease-prone countries are still poorly prepared for an emergency response. This paper examines knowledge gaps in both emerging and neglected arthropod-borne flavivirus infectious diseases associated with poverty and their implications for fostering local, national and regional emerging disease preparedness, effective and robust surveillance-response systems, sustained control and eventual elimination. Strengthening the regional and Global Health Flavivirus Surveillance-Response Network (GHFV-SRN) with other models of socio-economic, climatic, environmental and ecological mitigation and
During mosquito transmission, malaria ookinetes must cross a chitin-containing structure known as... more During mosquito transmission, malaria ookinetes must cross a chitin-containing structure known as the peritrophic matrix (PM), which surrounds the infected blood meal in the mosquito midgut. In turn, ookinetes produce multiple chitinase activities presumably aimed at disrupting this physical barrier to allow ookinete invasion of the midgut epithelium. Plasmodium chitinase activities are demonstrated targets for human and avian malaria transmission blockade with the chitinase inhibitor allosamidin. Here, we identify and characterize the first chitinase gene of a rodent malaria parasite, Plasmodium berghei. We show that the gene, named PbCHT1, is a structural ortholog of PgCHT1 of the avian malaria parasite Plasmodium gallinaceum and a paralog of PfCHT1 of the human malaria parasite Plasmodium falciparum. Targeted disruption of PbCHT1 reduced parasite infectivity in Anopheles stephensi mosquitoes by up to 90%. Reductions in infectivity were also observed in ookinete feeds-an artificial situation where midgut invasion occurs before PM formationsuggesting that PbCHT1 plays a role other than PM disruption. PbCHT1 null mutants had no residual ookinete-derived chitinase activity in vitro, suggesting that P. berghei ookinetes express only one chitinase gene. Moreover, PbCHT1 activity appeared insensitive to allosamidin inhibition, an observation that raises questions about the use of allosamidin and components like it as potential malaria transmission-blocking drugs. Taken together, these findings suggest a fundamental divergence among rodent, avian, and human malaria parasite chitinases, with implications for the evolution of Plasmodium-mosquito interactions.
Membrane skeletons are cytoskeletal elements that have important roles in cell development, shape... more Membrane skeletons are cytoskeletal elements that have important roles in cell development, shape, and structural integrity. Malaria parasites encode a conserved family of putative membrane skeleton proteins related to articulins. One member, IMC1a, is expressed in sporozoites and localizes to the pellicle, a unique membrane complex believed to form a scaffold onto which the ligands and glideosome are arranged to mediate parasite motility and invasion. IMC1b is a closely related structural paralogue of IMC1a, fostering speculation that it could be functionally homologous but in a different invasive life stage. Here we have generated genetically modified parasites that express IMC1b tagged with green fluorescent protein, and we show that it is targeted exclusively to the pellicle of ookinetes. We also show that IMC1b-deficient ookinetes display abnormal cell shape, reduced gliding motility, decreased mechanical strength, and reduced infectivity. These findings are consistent with a membrane skeletal role of IMC1b and provide strong experimental support for the view that membrane skeletons form an integral part of the pellicle of apicomplexan zoites and function to provide rigidity to the pellicular membrane complex. The similarities observed between the loss-of-function phenotypes of IMC1a and IMC1b show that membrane skeletons of ookinetes and sporozoites function in an overall similar way. However, the fact that ookinetes and sporozoites do not use the same IMC1 protein implies that different mechanical properties are required of their respective membrane skeletons, likely reflecting the distinct environments in which these life stages must operate.
embrane skeletons are structural elements that provide mechanical support to the plasma membrane ... more embrane skeletons are structural elements that provide mechanical support to the plasma membrane and define cell shape. Here, we identify and characterize a putative protein component of the membrane skeleton of the malaria parasite. The protein, named PbIMC1a, is the structural orthologue of the Toxoplasma gondii inner membrane complex protein 1 (TgIMC1), a component of the membrane skeleton in tachyzoites. Using targeted gene disruption in the rodent malaria species Plasmodium berghei , we show that M PbIMC1a is involved in sporozoite development, is necessary for providing normal sporozoite cell shape and mechanical stability, and is essential for sporozoite infectivity in insect and vertebrate hosts. Knockout of PbIMC1a protein expression reduces, but does not abolish, sporozoite gliding locomotion. We identify a family of proteins related to PbIMC1a in Plasmodium and other apicomplexan parasites. These results provide new functional insight in the role of membrane skeletons in apicomplexan parasite biology. We used BLAST homology searches with the TgIMC1 amino acid sequence to identify orthologous genes in Plasmodium . The
Frontiers in Cellular and Infection Microbiology, Feb 10, 2023
Emerging mosquito-borne diseases and novel biocontrol strategies Mosquito-borne diseases threaten... more Emerging mosquito-borne diseases and novel biocontrol strategies Mosquito-borne diseases threaten more than 40% of the world's population and are an increasingly serious global health challenge . A report released by the World Health Organization (WHO) showed that malaria caused 247 million cases and 619,000 deaths in 2021, and there is no significant progress in current malaria control (World Health Organization, 2023a). The global incidence and number of reported epidemic areas of dengue have also grown dramatically (World Health Organization, 2023). Moreover, Zika, a newly emerged mosquito-borne disease associated with neurological complications, has recently caused several large outbreaks involving 89 countries and territories (World Health Organization, 2023b). Furthermore, no efficient vaccines or drugs for diseases such as dengue and Zika are publicly available, and vector control remains largely dependent on traditional insecticide-based strategies . Notably, the limitation of the current vector control effect is partly due to the overreliance on chemical control . Chemical insecticides used to be the primary strategy for mosquito control, but insecticide resistance has widely emerged in mosquitoes in recent years (World Health Organization, 2018; Peng et al., 2022). Extensive use of insecticides both in mosquito control and agriculture led to environmental pollution and exerted effects on non-targeted organisms (Deng et al., 2019). Thus, there is a growing need for more sustainable, environmentally friendly, and low-cost vector control strategies that can be implemented on a large scale to harness insecticide-resistant mosquitoes and reduce mosquito-borne disease burden. Biological control agents are important alternatives or complements to chemical insecticides. Combined with genetic approaches (e.g., transgenesis and paratransgenesis) and other biological rear and release theories, novel approaches, including entomopathogenic fungi (Metarhizium anisopliae and Beauveria bassiana) (Deng et al., 2019; Peng et al., 2022), symbiotic bacteria (Wolbachia) , lethal bacteria (Bacillus thuringiensis) Frontiers in Cellular and Infection Microbiology frontiersin.org 01
Hard ticks are causative agents of physical illness and vectors of important diseases of human an... more Hard ticks are causative agents of physical illness and vectors of important diseases of human and livestock. The hard tick Hyalomma dromedarii Koch, 1844 is a major ectoparasite of livestock in the Kingdom of Saudi Arabia (KSA), of which, the onehumped dromedaries Camelus dromedarius is the most economically and culturally important and a potential reservoir of Middle East respiratory syndrome coronavirus (MERSCoV) disease. Here we report on the molecular phylogenetic diversity of H. dromedarii collected from camels in the Eastern Province of KSA based on the mitochondrial cytochrome oxidase I (COI) gene. Maximum likelihood (ML) phylogenetic analysis of COI sequences of the studied ticks identified 11 haplotypes. All H. dromedarii ticks from KSA belonged to eight haplotypes diverged into two distinguished genetic clades (A-B). These results indicate that H. dromedarii ticks from KSA are monophyletic species with two distinguished lineages with low intra-specific genetic divergence and sharply structured isolated populations with high level of genetic differentiation. This is a first report of DNA barcode of H. dromedarii ticks from KSA and the Arabian Peninsula, which is an important step towards broader phylogenetic studies on larger tick samples from the region. The studies are important for better understanding its interactions with camels and other hosts and role in zoonotic disease transmission (e.g. MERS-CoV or Alkhurma virus) to pinpoint effective control strategies.
A novel rotator trap was evaluated to determine the diel activity patterns and physiological stat... more A novel rotator trap was evaluated to determine the diel activity patterns and physiological state of adult female mosquitoes in St. Augustine, FL, U.S.A. Culex nigripalpus were most active from 19:00-21:00, followed by 1:00-3:00, based on collections from the novel rotator trap. Furthermore, analysis of the physiological state of female mosquitoes collected by the novel rotator trap suggested that non-parous (nulliparous) host-seeking mosquitoes were more frequently active in the 21:00-23:00 and 09:00-19:00 time frames. Parous host-seeking mosquitoes were more frequently collected from 19:00-21:00 and 1:00-3:00. A low abundance of gravid females was collected by the rotator trap, so analysis of their activity periods was inconclusive. These results indicate that the novel rotated trap could be used to detect the diel activity patterns of adult mosquitoes in mosquito control programs and more testing should be conducted in the future.
Transactions of The Royal Society of Tropical Medicine and Hygiene, Apr 1, 2012
Sand fly salivary fluid contains numerous proteins that modulate host immune responses to infecti... more Sand fly salivary fluid contains numerous proteins that modulate host immune responses to infection and facilitate blood-feeding and establishing Leishmania infection. Salivary proteins are differentially expressed in adaptation to the host, the meal type and ecological factors. We report on the morphometrics and protein composition of salivary glands of colonised Phlebotomus papatasi and P. langeroni sand flies from Egypt. Female glands were dissected at day 1 (D1, unfed), day 2 (D2, sugar-fed), day 3 (D3, blood-fed) and day 7 (D7, blood-digested). The salivary glands are composed of two lobes: heterogeneous in P. papatasi and homogeneous in P. langeroni. Lobe sizes varied considerably with fly age and feeding state; D3 flies had the largest lobe sizes and protein content. The P. papatasi flies had larger lobes and higher protein content than the P. langeroni flies. The P. papatasi D1 flies had 15 protein bands that decreased in the D2, D3 and D7 flies to 10 bands in the Sinai flies and 9 bands in the Alexandria flies. All P. langeroni flies had 12 protein bands but with different intensities. The results reveal inter-specific variation between P. papatasi and P. langeroni, while no intra-specific variation between P. papatasi strains. These results increase our understanding of salivary gland protein composition and blood-feeding behaviour in Old World sand flies with implications for leishmaniasis epidemiology and control.
Journal of Infection and Public Health, May 1, 2020
Increasing emergence and spread of Nipah, ZIKV and Ebola case and potential outbreaks threats hav... more Increasing emergence and spread of Nipah, ZIKV and Ebola case and potential outbreaks threats have been reported in several regions around the globe. Yet, emerging Nipah, Ebola and Zika viral diseases outbreaks have been indirectly linked to substantially globalization of trade and travel, climate change and intense urbanization impact, healthcare and socioeconomic inequities as well in affected community settings. Although no case has been documented in Saudi Arabia, there is a great risk of sudden emergence of any of these viruses and others via introducing among pilgrims coming from endemic regions during ritual ceremonies of mass gatherings. Consequently, promoting and investing on new and sensitive proven effective and innovative surveillance and monitoring approaches, including enhanced risk communication, improved integrated vectors surveillance in addition to improved sustainable highly pathogens surveillance control programs to human motility and environmental sanitation strategies all represent 'One Health' approach implementation strategic core. Initiation, development and implementation leaded by Saudi government and international stakeholders' of new partnership, coordinated response leadership and resource mobilization for multidisciplinary and intersectorial advocacy on emerging viral disease outbreaks, accompanied with R&D roadmap and taskforce is crucial. More efforts in epidemiological and laboratory early screening and surveillance of highly pathogenic germs/microbes, and confirmation of asymptomatic and syndromic cases amongst suspected Hajj and Umrah pilgrims, local vulnerable populations and expatriate workers is vital in generating reliable data and data sharing platform for timely risk communication and tourist information update, appropriate immunization campaigns or safe and efficacious care delivery implementation. Moreover, increase Hajj/Umrah mass gathering emergency outbreak preparedness, pilgrims health education and engagement outreach, pre-, during and post programs coverage and effectiveness is needed through One Health approach integration in attaining pilgrims and local population health safety and security, in advancing Saudi sustainable health development goals.
Journal of the Egyptian Society of Parasitology, Apr 1, 2010
Medicinal plants have long history as important components in traditional medicine, and food of h... more Medicinal plants have long history as important components in traditional medicine, and food of humans since ancient Egyptians and Chinese. Naturally occurring botanical compounds contain a broad range of chemical active ingredients can intervene in all biological processes of the mosquito, thus interrupt its life cycle and dispersal and reduce harms to humans and animals. Many medicinal plants were tested for their pesticide and repellent potential, as crude material, essential oils or individual active ingredients. This article reviewed studies on the efficacy of many well known and commonly used safe medicinal plants or their products in controlling the mosquitoes; Aedes aegypti, Anopheles gambiae, An. stephensi and Culex quinquefasciatus and the ticks, Dermacentor variabilis, Amblyomma americanum, Ixodes scapularis and I. ricinus. Promising and encouraging results were obtained against these arthropod-vectors of zoonotic diseases.
There are at least five common mosquito-borne viruses (MBVs) recorded in Egypt, including dengue ... more There are at least five common mosquito-borne viruses (MBVs) recorded in Egypt, including dengue virus (DENV), Rift Valley fever virus (RVFV), West Nile virus (WNV), Chikungunya virus, and Sindbis virus. Unexpected outbreaks caused by MBVs reflect the deficiencies of the MBV surveillance system in Egypt. This systematic review characterized the epidemiology of MBV prevalence in Egypt. Human, animal, and vector prevalence studies on MBVs in Egypt were retrieved from Web of Science, PubMed, and Bing Scholar, and 33 eligible studies were included for further analyses. The monophyletic characterization of the RVFV and WNV strains found in Egypt, which spans about half a century, suggests that both RVFV and WNV are widely transmitted in this nation. Moreover, the seropositive rates of DENV and WNV in hosts were on the rise in recent years, and spillover events of DENV and WNV to other countries from Egypt have been recorded. The common drawback for surveillance of MBVs in Egypt is the la...
With over 72 countries and territories affected worldwide with Aedes mosquito-transmitted Zika vi... more With over 72 countries and territories affected worldwide with Aedes mosquito-transmitted Zika virus disease and estimated over millions of people are at high ZIKV risk including pregnant women in these Aedes mosquito-prone settings. The recent epidemic events further stress the everincreasing need and value of national public health evidence-based decision-making policy, budget allocation and programs in protecting vulnerable communities. This paper highlights Aedes vector ecological determinants and impacts mitigation and adaptation approaches in strengthening and in scaling-up integrated Aedes mosquito management programs and ZIKV epidemics prevention and containment measures across Aedes-prone African countries. The paper advocates for the urgency to establish and strengthen effective and robust local and national public health laboratories surveillance and inter-sectorial monitoring capabilities in scaling-up evidence-based and integrated Aedes vector management programs and Zi...
Susceptibility status of Ae. albopictus and Ae. aegypti was evaluated in different localities of ... more Susceptibility status of Ae. albopictus and Ae. aegypti was evaluated in different localities of four towns namely Samanabad, Nishtar, Ravi and Iqbal town in Lahore district, Eastern Punjab, Pakistan. Susceptibility test using WHO test kits was applied on adult females (12-24) hrs. Post emergence (nonblood fed) live mosquitoes under laboratory conditions at 27-29 0C temperature and 85-95% humidity. Ae. aegypti and Ae. Albopictus were found resistant to 4% DDT with < 36.28% mortality. Both species were also found resistant against 0.05% deltamethrin, 0.05%, lambdacyhalothrin and 0.75% permethrin at all localities with <75.00%, <87.00% and <81.05% mortalities respectively. Ae. albopictus was found resistant to 0.1% bendiocarb at Samanabad and Iqbal towns, while resistance possible to be confirmed at Nishtar and Ravi towns. Ae. aegypti found susceptible to 0.1% bendiocarb at Samanabad town, resistant at Ravi town and resistance possible to be confirmed (incipient) at Nishta...
Gene mutations on target sites can be a valuable indicator of the status of insecticide resistanc... more Gene mutations on target sites can be a valuable indicator of the status of insecticide resistance. Jeddah, a global commercial and major port-of-entry city, is bearing the brunt of dengue disease burden in Saudi Arabia. In the current study, six genotypes of three codon combinations (989, 1016, and 1534) were observed on voltage-gated sodium channel (VGSC) gene in Jeddah’s Aedes aegypti population, with PGF/PGC as the dominant one. Two types of introns between exon 20 and 21 on VGSC have been identified for the first time in Ae. aegypti in Saudi Arabia. Statistical and phylogenetic analyses showed that the intron type was significantly associated with the 1016 allele and may reflect the history of insecticide treatment in different continents. In addition, fixation of the L1014F allele on VGSC and G119S on acetylcholinesterase 1 gene was detected in local Culex quinquefasciatus populations, with frequencies of 95.24 and 100%, respectively. To the best of our knowledge, this is the ...
A novel rotator trap was evaluated to determine the diel activity patterns and physiological stat... more A novel rotator trap was evaluated to determine the diel activity patterns and physiological state of adult female mosquitoes in St. Augustine, FL, U.S.A. Culex nigripalpus were most active from 19:00-21:00, followed by 1:00-3:00, based on collections from the novel rotator trap. Furthermore, analysis of the physiological state of female mosquitoes collected by the novel rotator trap suggested that non-parous (nulliparous) host-seeking mosquitoes were more frequently active in the 21:00-23:00 and 09:00-19:00 time frames. Parous host-seeking mosquitoes were more frequently collected from 19:00-21:00 and 1:00-3:00. A low abundance of gravid females was collected by the rotator trap, so analysis of their activity periods was inconclusive. These results indicate that the novel rotated trap could be used to detect the diel activity patterns of adult mosquitoes in mosquito control programs and more testing should be conducted in the future.
Africa being part of the global village is challenged by unprecedented and persistent emerging in... more Africa being part of the global village is challenged by unprecedented and persistent emerging infectious diseases threats and outbreaks. Recent memories of the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) outbreaks in Saudi Arabia (2012) and South Korea (2015), West Africa Ebola viral disease outbreak and public health humanitarian crisis (2014) and China's SARS outbreaks. Various differences and similarities between these diseases have triggered serious concerns and magnified that similar outbreaks could occur anywhere in the world with lingering health complications, socio-political and economic crises. Yet, there is dearth of knowledge on MERS-CoV reservoirs, risk factors of emergence, infectivity and transmissibility in Africa and globally. This paper highlights forward approaches and key activities to the African Union, governments and institutions and all stakeholders including public-private partnership. These play paramount roles in providing information and support to address MERS-CoV and other emerging infectious diseases research gaps, (2) promoting community alertness and resilience in preparedness, (3) fostering effective and coordinated logistics in risk communication, planning and response in MERS-CoV public mobilization literacy and awareness, advocacy and mitigation. There is an urgent need to establish an integrated and strategic evidence-based local and nationwide surveillance and response capacity, (5) better understand the MERS-CoV animal reservoir(s) and human-human infectivity and transmissibility, and (6) implement informed community-based or national threat and epidemics actionable emergency insurance facility and compensation schemes. Conclusively, improved early warning, active and integrated epidemiological and genomic surveillance indicators data gathering to inform and guide effective and community resilience capability in consolidating and upholding knowledge gains from "One Health Surveillance Network" and best practices in achieving "One Health" and global health security.
Dengue is still a substantial vector-borne viral disease threat and burden of public health impor... more Dengue is still a substantial vector-borne viral disease threat and burden of public health importance worldwide. This situation is complicated by dengue virus unprecedented resurgence and persistence of varied serotypes in endemic-prone areas, and man-made and natural activities consequences that promote vector emergence, transmission dynamics and spread across the Asia-Pacific region. There is an urgent need to strengthen operational and contextual surveillance-response research in improving early detection of active reservoir detection, novel drug in case management and quality evidence-based response including the deployment of dengue mass vaccination. Moreover, sustained mapping and watching of dengue risk factors or determinants, performance and outcome indicators of control or elimination programs effectiveness in defining minimum effective data towards community knowledge-based decision-making policy and effective response packages is imperative. Moreover, implementation of a robust, integrated dengue early warning surveillance, monitoring and response systems metrics is required for evidence-based, timely and cost-effective contextual mitigation strategies, and innovative interventions.
Since its discovery in 1947 in Uganda and control and eradication efforts have aimed at its vecto... more Since its discovery in 1947 in Uganda and control and eradication efforts have aimed at its vectors (Aedes mosquitoes) in Latin America in the 1950s, an absolute neglect of Zika programs and interventions has been documented in Aedes endemic and epidemic-prone countries. The current unprecedented Zika viral epidemics and rapid spread in the Western hemisphere pose a substantial global threat, with associated anxiety and consequences. The lack of safe and effective drugs and vaccines against Zika or dengue epidemics further buttresses the realization from the West Africa Ebola outbreak that most emerging disease-prone countries are still poorly prepared for an emergency response. This paper examines knowledge gaps in both emerging and neglected arthropod-borne flavivirus infectious diseases associated with poverty and their implications for fostering local, national and regional emerging disease preparedness, effective and robust surveillance-response systems, sustained control and eventual elimination. Strengthening the regional and Global Health Flavivirus Surveillance-Response Network (GHFV-SRN) with other models of socio-economic, climatic, environmental and ecological mitigation and
The Millennium Development Goals (MDGs) made a marked transformation for neglected and vulnerable... more The Millennium Development Goals (MDGs) made a marked transformation for neglected and vulnerable communities in the developing countries from the start, but infectious diseases of poverty (IDoPs) continue to inflict a disproportionate global public health burden with associated consequences, thereby contributing to the vicious cycle of poverty and inequity. However, the effectiveness and large-scale coverage of artemisinin combination therapy (ACT) have revolutionized malaria treatment just as the control of lymphatic filariasis (LF) and onchocerciasis have benefitted from harnessing the broad-spectrum effect of avermectin-based derivatives. The paradigm shift in therapeutic approach, effected by these two drugs and their impact on community-based interventions of parasitic diseases plaguing the endemic low- and middle-income countries (LIMCs), led to the Nobel Prize in Physiology or Medicine in 2015. However, the story would not be complete without mentioning praziquantel. The hug...
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