bims-mosdis 2021-12-12 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2021‒12‒12
eighteen papers selected by
Richard Halfpenny
Staffordshire University

Adult Mosquito Fauna of Kura-Aras Basin.
Evaluation of Pyriproxyfen Effects on Aedes aegypti and Predatory Mosquito Toxorhynchites rutilus (Diptera: Culicidae).
Evaluating the efficacy, impact, and feasibility of community-based house screening as a complementary malaria control intervention in southern Africa: a study protocol for a household randomized trial.
The effect of a mass distribution of insecticide-treated nets on insecticide resistance and entomological inoculation rates of Anopheles gambiae s.l. in Bandundu City, Democratic Repub`lic of Congo.
Assessment of community support for Wolbachia-mediated population suppression as a control method for Aedes aegypti mosquitoes in a community cohort in Puerto Rico.
Larvae ecology and adult activity of Aedes mariae (Diptera: Culicidae) in a touristic rock-pool area of the Balearic Islands (Western Mediterranean).
The impact of climate suitability, urbanisation, and connectivity on the expansion of dengue in 21st century Brazil.
Safety study of Rift Valley Fever human vaccine candidate (DDVax) in mosquitoes.
Challenges, Advances and Opportunities in Exploring Natural Products to Control Arboviral Disease Vectors.
The Economic Value of Genetically Engineered Mosquitoes as a Malaria Control Strategy Depends on Local Transmission Rates.
Discovery of mosquitocides from fungal extracts through a high-throughput cytotoxicity-screening approach.
High resolution proteomics of Aedes aegypti salivary glands infected with either dengue, Zika or chikungunya viruses identify new virus specific and broad antiviral factors.
Community knowledge, perceptions, and practices regarding malaria and its control in Jabi Tehnan district, Amhara Region, Northwest Ethiopia.
Civilian-military malaria outbreak response in Thailand: an example of multi-stakeholder engagement for malaria elimination.
Four decades of epidemiological data reveal trajectories towards malaria elimination in Kheda district (Gujarat), western part of India.
Using observed incidence to calibrate the transmission level of a mathematical model for Plasmodium vivax dynamics including case management and importation.
Epidemiological Trends of Malaria in Five Years and under Children of Nsanje District in Malawi, 2015-2019.
Insilico Functional Analysis of Genome-Wide Dataset From 17,000 Individuals Identifies Candidate Malaria Resistance Genes Enriched in Malaria Pathogenic Pathways.

Turkiye Parazitol Derg. 2021 Dec 02. 45(4): 280-286

Adult Mosquito Fauna of Kura-Aras Basin.

Berna Demirci.

  OBJECTIVE: To identify the adult mosquito species of Kura-Aras Basin, which includes Kars-Ardahan Plateau and Aras Valley, mosquito sampling was done in August and September 2020.METHODS: Adult mosquitoes were collected using new Jersey light traps and mouth aspirators.
RESULTS: A total of 5.361 adult mosquito species belonging to five genera (Aedes caspius, Aedes vexans, Anopheles hyrcanus, Anopheles maculipennis s.l., Anopheles superpictus, Culex hortensis, Culex theileri, Culex pipiens s.l., Coquillettidia richiardii, Culiseta annulata, Culiseta longiearolata and Culiseta subochera) were sampled.
CONCLUSION: Species detected in the study area are important vectors for public health, since they carry pathogens, such as malaria, West Nile virus, and various nematodes. These species can be used for arbovirus and malaria research studies.

Keywords:  Aedes; Anopheles vector.; Culex spp.; Kura-Aras Basin; mosquito

DOI:  https://doi.org/10.4274/tpd.galenos.2021.80299
J Med Entomol. 2021 Dec 03. pii: tjab193. [Epub ahead of print]

Evaluation of Pyriproxyfen Effects on Aedes aegypti and Predatory Mosquito Toxorhynchites rutilus (Diptera: Culicidae).

Abdullah A Alomar, Barry W Alto.

  Control of mosquito vectors of pathogens remains heavily dependent on the application of conventional insecticides. Pyriproxyfen (PPF) is a novel insecticide that has been proposed for use in autodissemination techniques to control mosquito vectors. The use of PPF can inhibit adult emergence but does not inhibit larval development. This feature is favorable for controlling Aedes aegypti because PPF has the potential to work in combination with natural sources of mortality (competition, predation) during the immature stages, and other control methods, including biocontrol agents that further suppress recruitment of adult mosquitoes. However, the PPF effects on life-history traits of Ae. aegypti in comparison to predatory mosquito Toxorhynchites rutilus, a source of mortality, are not fully understood. Here, we show that larval exposure to PPF concentrations that inhibit 50-90% of adult emergence in Ae. aegypti had a negligible effect on adult emergence and lifespan of Tx. rutilus. Weights of adult Ae. aegypti and Tx. rutilus were not influenced by PPF. These findings suggest that the use of PPF to control mosquito vectors may have low effects on mosquito biocontrol agents. Our results extend and confirm earlier data showing that PPF has potential to implement with Tx. rutilus to suppress Ae. aegypti and provide an additional advantage of PPF use in autodissemination control strategies.

Keywords:   Toxorhynchites rutilus ; Aedes aegypti; adult emergence; biocontrol agent; pyriproxyfen

DOI:  https://doi.org/10.1093/jme/tjab193
Trials. 2021 Dec 06. 22(1): 883

Evaluating the efficacy, impact, and feasibility of community-based house screening as a complementary malaria control intervention in southern Africa: a study protocol for a household randomized trial.

Onyango P Sangoro, Ulrike Fillinger, Kochelani Saili, Theresia Estomih Nkya, Rose Marubu, Freddie Masaninga, Sonia Casimiro Trigo, Casper Tarumbwa, Busiku Hamainza, Candrinho Baltazar, Joseph Mberikunashe, Brian Chisanga, Kassie Menale, Emmanuel Chanda, Clifford Maina Mutero.

  BACKGROUND: Concerted effort to control malaria has had a substantial impact on the transmission of the disease in the past two decades. In areas where reduced malaria transmission is being sustained through insecticide-based vector control interventions, primarily long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), non-insecticidal complementary tools will likely be needed to push towards malaria elimination. Once interruption in local disease transmission is achieved, insecticide-based measures can be scaled down gradually and eventually phased out, saving on costs of sustaining control programs and mitigating any unintended negative health and environmental impacts posed by insecticides. These non-insecticidal methods could eventually replace insecticidal methods of vector control. House screening, a non-insecticidal method, has a long history in malaria control, but is still not widely adopted in sub-Saharan Africa. This study aims to add to the evidence base for this intervention in low transmission settings by assessing the efficacy, impact, and feasibility of house screening in areas where LLINs are conventionally used for malaria control.METHODS: A two-armed, household randomized clinical trial will be conducted in Mozambique, Zambia, and Zimbabwe to evaluate whether combined the use of house screens and LLINs affords better protection against clinical malaria in children between 6 months and 13 years compared to the sole use of LLINs. Eight hundred households will be enrolled in each study area, where 400 households will be randomly assigned the intervention, house screening, and LLINs while the control households will be provided with LLINs only. Clinical malaria incidence will be estimated by actively following up one child from each household for 6 months over the malaria transmission season. Cross-sectional parasite prevalence will be estimated by testing all participating children for malaria parasites at the beginning and end of each transmission season using rapid diagnostic tests. CDC light traps and pyrethrum spray catches (PSC) will be used to sample adult mosquitoes and evaluate the impact of house screening on indoor mosquito density, species distribution, and sporozoite rates.
DISCUSSION: This study will contribute epidemiological data on the impact of house screening on malaria transmission and assess the feasibility of its implementation on a programmatic scale.
TRIAL REGISTRATION: ClinicalTrials.gov PACTR202008524310568 . Registered on August 11, 2020.

Keywords:  House screening; Integrated vector management; Malaria elimination; Residual malaria transmission

DOI:  https://doi.org/10.1186/s13063-021-05768-7
Pan Afr Med J. 2021 ;40 118

The effect of a mass distribution of insecticide-treated nets on insecticide resistance and entomological inoculation rates of Anopheles gambiae s.l. in Bandundu City, Democratic Repub`lic of Congo.

Emery Metelo-Matubi, Josué Zanga, Guillaume Binene, Nono Mvuama, Solange Ngamukie, Jadis Nkey, Pauline Schopp, Maxwell Bamba, Seth Irish, Jean Nguya-Kalemba-Maniania, Sylvie Fasine, Jonas Nagahuedi, Jean-Jacques Muyembe, Paul Mansiangi.

  Introduction: insecticide-treated nets (ITNs) remain the mainstay of malaria vector control in the Democratic Republic of Congo. However, insecticide resistance of malaria vectors threatens their effectiveness. Entomological inoculation rates and insecticide susceptibility in Anopheles gambiae s.l. were evaluated before and after mass distribution of ITNs in Bandundu City for possible occurrence of resistance.Methods: a cross-sectional study was conducted from 15th July 2015 to 15th June 2016. Adult mosquitoes were collected using pyrethrum spray catches and human landing catches and identified to species level and tested for the presence of sporozoites. Bioassays were carried out before and after distribution of ITNs to assess the susceptibility of adult mosquitoes to insecticides. Synergist bioassays were also conducted and target site mutations assessed using Polymerase chain reaction (PCR).
Results: a total of 1754 female An. gambiae s.l. were collected before and after deployment of ITNs. Fewer mosquitoes were collected after the distribution of ITNs. However, there was no significant difference in sporozoite rates or the overall entomological inoculation rate before and after the distribution of ITNs. Test-mosquitoes were resistant to deltamethrin, permethrin, and Dichlorodiphenyltrichloroethane but susceptible to bendiocarb. Pre-exposure of mosquitoes to Piperonyl butoxide increased their mortality after exposure to permethrin and deltamethrin. The frequency of the Kinase insert domain receptor (kdr)-West gene increased from 92 to 99% before and after the distribution of nets, respectively.
Conclusion: seasonal impacts could be a limiting factor in the analysis of these data; however, the lack of decrease in transmission after the distribution of new nets could be explained by the high-level of resistance to pyrethroid.

Keywords:  Anopheles gambiae; insecticide-treated nets; resistance; sporozoite rate

DOI:  https://doi.org/10.11604/pamj.2021.40.118.27365
PLoS Negl Trop Dis. 2021 Dec 06. 15(12): e0009966

Assessment of community support for Wolbachia-mediated population suppression as a control method for Aedes aegypti mosquitoes in a community cohort in Puerto Rico.

Liliana Sánchez-González, Laura E Adams, Rafael Saavedra, Emma M Little, Nicole A Medina, Chelsea G Major, Marina Bruck, Julieanne Miranda, Coral Rosado-Santiago, Kyle Ryff, Marianyoly Ortiz, Grayson Brown, Roberto Barrera, Carmen L Pérez-Guerra, Vanessa Rivera-Amill, Gabriela Paz-Bailey.

Arboviral diseases transmitted by Aedes species mosquitoes pose an increasing public health challenge in tropical regions. Wolbachia-mediated population suppression (Wolbachia suppression) is a vector control method used to reduce Aedes mosquito populations by introducing male mosquitoes infected with Wolbachia, a naturally occurring endosymbiotic bacterium. When Wolbachia-infected male mosquitoes mate with female wild mosquitoes, the resulting eggs will not hatch. Public support is vital to the successful implementation and sustainability of vector control interventions. Communities Organized to Prevent Arboviruses (COPA) is a cohort study to determine the incidence of arboviral disease in Ponce, Puerto Rico and evaluate vector control methods. Focus groups were conducted with residents of COPA communities to gather their opinion on vector control methods; during 2018-2019, adult COPA participants were interviewed regarding their views on Wolbachia suppression; and a follow-up questionnaire was conducted among a subset of participants and non-participants residing in COPA communities. We analyzed factors associated with support for this method. Among 1,528 participants in the baseline survey, median age was 37 years and 63% were female. A total of 1,032 (68%) respondents supported Wolbachia suppression. Respondents with an income of $40,000 or more were 1.34 times as likely [95% CI: 1.03, 1.37] to support Wolbachia suppression than those who earned less than $40,000 annually. Respondents who reported repellant use were 1.19 times as likely to support Wolbachia suppression [95% CI: 1.03, 1.37]. A follow-up survey in 2020 showed that most COPA participants (86%) and non-participants living in COPA communities (84%) supported Wolbachia suppression during and after an educational campaign. The most frequent questions regarding this method were related to its impact on human and animal health, and the environment. Continuous community engagement and education efforts before and during the implementation of novel vector control interventions are necessary to increase and maintain community support.

DOI: https://doi.org/10.1371/journal.pntd.0009966
Bull Entomol Res. 2021 Dec 09. 1-8

Larvae ecology and adult activity of Aedes mariae (Diptera: Culicidae) in a touristic rock-pool area of the Balearic Islands (Western Mediterranean).

Mikel Bengoa, Andreu Rotger, Raúl Luzón, Carlos Barceló.

  Mosquitoes are vectors of several diseases of medical concern such as malaria or dengue and can also negatively affect tourism and the life-quality of the neighbourhood. The species Aedes mariae (Sergent and Sergent, 1903) is a poorly studied mosquito that breeds in rock-pools of the Mediterranean coast. General Linear Mixed Models (GLMM) were used to determine drivers affecting the presence and abundance of this species. Abiotic and biotic factors were recorded in rock-pools with the presence of Ae. mariae sub-adults across a supralittoral area of Majorca Island (Balearic Islands, Spain) from July 2018 to June 2019. We tested how abiotic factors affected the presence of larvae, while the biotic factors were used to check their effect on larvae abundance. human landing collection was also conducted to assess the adult activity of this species. Valuable data were recorded to improve our knowledge about the bioecology of Ae. mariae in a touristic area of the island of Majorca. Salinity and pH were the most explanatory variables for the presence of Ae. mariae larvae. The presence of Posidonia oceanica (L.) Delile 1813 leaves negatively affected the abundance of Ae. mariae larvae while the presence of other fauna enhanced it. Adult females of Ae. mariae were active for 26 min after sunset in June and its host-seeking activity decreased during autumn months. Control methods against this species should be focussed on rock-pools and planning treatments according to tides, waves and precipitation.

Keywords:  Abundance; Majorca pH; Spain; algae; human landing; salinity; tourism

DOI:  https://doi.org/10.1017/S0007485321001024
PLoS Negl Trop Dis. 2021 Dec 09. 15(12): e0009773

The impact of climate suitability, urbanisation, and connectivity on the expansion of dengue in 21st century Brazil.

Sophie A Lee, Theodoros Economou, Rafael de Castro Catão, Christovam Barcellos, Rachel Lowe.

Dengue is hyperendemic in Brazil, with outbreaks affecting all regions. Previous studies identified geographical barriers to dengue transmission in Brazil, beyond which certain areas, such as South Brazil and the Amazon rainforest, were relatively protected from outbreaks. Recent data shows these barriers are being eroded. In this study, we explore the drivers of this expansion and identify the current limits to the dengue transmission zone. We used a spatio-temporal additive model to explore the associations between dengue outbreaks and temperature suitability, urbanisation, and connectivity to the Brazilian urban network. The model was applied to a binary outbreak indicator, assuming the official threshold value of 300 cases per 100,000 residents, for Brazil's municipalities between 2001 and 2020. We found a nonlinear relationship between higher levels of connectivity to the Brazilian urban network and the odds of an outbreak, with lower odds in metropoles compared to regional capitals. The number of months per year with suitable temperature conditions for Aedes mosquitoes was positively associated with the dengue outbreak occurrence. Temperature suitability explained most interannual and spatial variation in South Brazil, confirming this geographical barrier is influenced by lower seasonal temperatures. Municipalities that had experienced an outbreak previously had double the odds of subsequent outbreaks. We identified geographical barriers to dengue transmission in South Brazil, western Amazon, and along the northern coast of Brazil. Although a southern barrier still exists, it has shifted south, and the Amazon no longer has a clear boundary. Few areas of Brazil remain protected from dengue outbreaks. Communities living on the edge of previous barriers are particularly susceptible to future outbreaks as they lack immunity. Control strategies should target regions at risk of future outbreaks as well as those currently within the dengue transmission zone.

DOI: https://doi.org/10.1371/journal.pntd.0009773
Transbound Emerg Dis. 2021 Dec 10.

Safety study of Rift Valley Fever human vaccine candidate (DDVax) in mosquitoes.

Corey L Campbell, Trey K Snell, Susi Bennett, John H Wyckoff, Darragh Heaslip, Jordan Flatt, Emma K Harris, Daniel A Hartman, Elena Lian, Brian H Bird, Mark D Stenglein, Richard A Bowen, Rebekah C Kading.

  Rift Valley fever virus (RVFV) is a mosquito-borne pathogen with significant human and veterinary health consequences that periodically emerges in epizootics. RVFV causes fetal loss and death in ruminants and in humans can lead to liver and renal disease, delayed-onset encephalitis, retinitis, and in some cases severe hemorrhagic fever. A live attenuated vaccine candidate (DDVax), was developed by the deletion of the virulence factors NSs and NSm from a clinical isolate, ZH501, and has proven safe and immunogenic in rodents, pregnant sheep and non-human primates. Deletion of NSm also severely restricted mosquito midgut infection and inhibited vector-borne transmission. To demonstrate environmental safety, this study investigated the replication, dissemination and transmission efficiency of DDVax in mosquitoes following oral exposure compared to RVFV strains MP-12 and ZH501. Infection and dissemination profiles were also measured in mosquitoes 7 days after they fed on goats inoculated with DDvax or MP-12. We hypothesized that DDVax would infect mosquitoes at significantly lower rates than other RVFV strains and, due to lack of NSm, be transmission incompetent. Exposure of Ae. aegypti and Cx. tarsalis to 8 log10 plaque forming units (PFU)/mL DDVax by artificial bloodmeal resulted in significantly reduced DDVax infection rates in mosquito bodies compared to controls. Plaque assays indicated negligible transmission of infectious DDVax in Cx. tarsalis saliva (1/140 sampled) and none in Ae aegypti saliva (0/120). Serum from goats inoculated with DDVax or MP-12 did not harbor detectable infectious virus by plaque assay at 1, 2, or 3 days-post-inoculation. Infectious virus was, however, recovered from Aedes and Culex bodies that fed on goats vaccinated with MP-12 (13.8% and 4.6%, respectively), but strikingly, DDvax positive mosquito bodies were greatly reduced (4%, and 0%, respectively). Furthermore, DDVax did not disseminate to legs/wings in any of the goat-fed mosquitoes. Collectively, these results are consistent with a beneficial environmental safety profile. This article is protected by copyright. All rights reserved.

Keywords:  Aedes; Culex; arbovirus; vaccine; vector competence; vector-borne disease

DOI:  https://doi.org/10.1111/tbed.14415
Front Chem. 2021 ;9 779049

Challenges, Advances and Opportunities in Exploring Natural Products to Control Arboviral Disease Vectors.

Daniel P Demarque, Laila S Espindola.

  Natural products constitute an important source of molecules for product development. However, despite numerous reports of compounds and active extracts from biodiversity, poor and developing countries continue to suffer with endemic diseases caused by arboviral vectors, including dengue, Zika, chikungunya and urban yellow fever. Vector control remains the most efficient disease prevention strategy. Wide and prolonged use of insecticides has resulted in vector resistance, making the search for new chemical prototypes imperative. Considering the potential of natural products chemistry for developing natural products-based products, including insecticides, this contribution discusses the general aspects and specific characteristics involved in the development of drug leads for vector control. Throughout this work, we highlight the obstacles that need to be overcome in order for natural products compounds to be considered promising prototypes. Moreover, we analyze the bottlenecks that should be addressed, together with potential strategies, to rationalize and improve the efficiency of the drug discovery process.

Keywords:  Aedes aegypti; arboviral vectors; dengue; drug discovery; insecticides; natural products

DOI:  https://doi.org/10.3389/fchem.2021.779049
Biotechnol J. 2021 Dec 06. e2100373

The Economic Value of Genetically Engineered Mosquitoes as a Malaria Control Strategy Depends on Local Transmission Rates.

Katherine Lacy, K Aleks Schaefer, Daniel P Scheitrum, Eili Y Klein.

  AIM: This paper assesses the economic value of genetically engineered (GE) Anopheles gambiae mosquitoes as a malaria control strategy.MAIN METHODS: We use an epidemiological-economic model of malaria transmission to evaluate this technology for a range of village-level transmission settings. In each setting, we evaluate public health outcomes following introduction of GE mosquitoes relative to a "status quo" baseline scenario. We also assess results both in contrast to-and in combination with-a Mass Drug Administration (MDA) strategy.
MAIN RESULTS: We find that-in low transmission settings-the present value public health benefits of GE mosquito release are substantial, both relative to status quo dynamics and MDA. In contrast, in high transmission settings, the release of GE mosquitoes may increase steady-state infection rates.
CONCLUSIONS AND IMPLICATIONS: Our results indicate that there are substantial policy complementarities when GE mosquito release is combined with local MDA-the combined control strategy can lead to local eradication. This article is protected by copyright. All rights reserved.

Keywords:  genetically engineered mosquitoes; integrative assessment model

DOI:  https://doi.org/10.1002/biot.202100373
Parasit Vectors. 2021 Dec 04. 14(1): 595

Discovery of mosquitocides from fungal extracts through a high-throughput cytotoxicity-screening approach.

Liang Jin, Guodong Niu, Limei Guan, Julian Ramelow, Zhigao Zhan, Xi Zhou, Jun Li.

  BACKGROUND: Mosquitoes transmit a variety of diseases. Due to widespread insecticide resistance, new effective pesticides are urgently needed. Entomopathogenic fungi are widely utilized to control pest insects in agriculture. We hypothesized that certain fungal metabolites may be effective insecticides against mosquitoes.METHODS: A high-throughput cytotoxicity-based screening approach was developed to search for insecticidal compounds in our newly established global fungal extract library. We first determined cell survival rates after adding various fungal extracts. Candidate insecticides were further analyzed using traditional larval and adult survival bioassays.
RESULTS: Twelve ethyl acetate extracts from a total of 192 fungal extracts displayed > 85% inhibition of cabbage looper ovary cell proliferation. Ten of these 12 candidates were confirmed to be toxic to Anopheles gambiae Sua5B cell line, and six showed > 85% inhibition of Anopheles mosquito cell growth. Further bioassays determined a LC50, the lethal concentration that kills 50% of larval or adult mosquitoes, of 122 µg/mL and 1.7 µg/mosquito, respectively, after 24 h for extract 76F6 from Penicillium toxicarium.
CONCLUSIONS: We established a high-throughput MTT-based cytotoxicity screening approach for the discovery of new mosquitocides from fungal extracts. We discovered a candidate extract from P. toxicarium that exhibited high toxicity to mosquito larvae and adults, and thus were able to demonstrate the value of our recently developed approach. The active fungal extracts discovered here are ideal candidates for further development as mosquitocides.

Keywords:  Anopheles gambiae; Mosquito; Penicillium toxicarium; Pesticides; Vector-borne diseases

DOI:  https://doi.org/10.1186/s13071-021-05089-3
Sci Rep. 2021 Dec 08. 11(1): 23696

High resolution proteomics of Aedes aegypti salivary glands infected with either dengue, Zika or chikungunya viruses identify new virus specific and broad antiviral factors.

Avisha Chowdhury, Cassandra M Modahl, Dorothée Missé, R Manjunatha Kini, Julien Pompon.

Arboviruses such as dengue (DENV), Zika (ZIKV) and chikungunya (CHIKV) viruses infect close to half a billion people per year, and are primarily transmitted through Aedes aegypti bites. Infection-induced changes in mosquito salivary glands (SG) influence transmission by inducing antiviral immunity, which restricts virus replication in the vector, and by altering saliva composition, which influences skin infection. Here, we profiled SG proteome responses to DENV serotype 2 (DENV2), ZIKV and CHIKV infections by using high-resolution isobaric-tagged quantitative proteomics. We identified 218 proteins with putative functions in immunity, blood-feeding or related to the cellular machinery. We observed that 58, 27 and 29 proteins were regulated by DENV2, ZIKV and CHIKV infections, respectively. While the regulation patterns were mostly virus-specific, we separately depleted four uncharacterized proteins that were upregulated by all three viral infections to determine their effects on these viral infections. Our study suggests that gamma-interferon responsive lysosomal thiol-like (GILT-like) has an anti-ZIKV effect, adenosine deaminase (ADA) has an anti-CHIKV effect, salivary gland surface protein 1 (SGS1) has a pro-ZIKV effect and salivary gland broad-spectrum antiviral protein (SGBAP) has an antiviral effect against all three viruses. The comprehensive description of SG responses to three global pathogenic viruses and the identification of new restriction factors improves our understanding of the molecular mechanisms influencing transmission.

DOI: https://doi.org/10.1038/s41598-021-03211-0
Malar J. 2021 Dec 09. 20(1): 459

Community knowledge, perceptions, and practices regarding malaria and its control in Jabi Tehnan district, Amhara Region, Northwest Ethiopia.

Abebe Asale, Zewdu Abro, Bayu Enchalew, Alayu Teshager, Aklilu Belay, Menale Kassie, Clifford Maina Mutero.

  BACKGROUND: Use of long-lasting insecticidal nets (LLINs), indoor residual spraying (IRS), community-based malaria education, prompt diagnosis and treatment are key programme components of malaria prevention and control in Ethiopia. However, the effectiveness of these interventions is often undermined by various challenges, including insecticide and drug resistance, the plasticity of malaria vectors feeding and biting behaviour, and certain household factors that lead to misuse and poor utilization of LLINs. The primary objective of this study was to document households' perceptions towards malaria and assess the prevalence of the disease and the constraints related to the ongoing interventions in Ethiopia (LLINs, IRS, community mobilization house screening).METHODS: The study was conducted in Jabi Tehnan district, Northwestern Ethiopia, from November 2019 to March 2020. A total of 3010 households from 38 villages were randomly selected for socio-economic and demographic survey. Focus group discussions (FGDs) were conducted in 11 different health clusters considering agro-ecological differences. A total of 1256 children under 10 years of age were screened for malaria parasites using microscopy to determine malaria prevalence. Furthermore, 5-year malaria trend analysis was undertaken based on data obtained from the district health office to understand the disease dynamics.
RESULTS: Malaria knowledge in the area was high as all FGD participants correctly identified mosquito bites during the night as sources of malaria transmission. Delayed health-seeking behaviour remains a key behavioural challenge in malaria control as it took patients on average 4 days before reporting the case at the nearby health facility. On average, households lost 2.53 working days per person-per malaria episode and they spent US$ 18 per person per episode. Out of the 1256 randomly selected under 10 children tested for malaria parasites, 11 (0.89%) were found to be positive. Malaria disproportionately affected the adult segment of the population more, with 50% of the total cases reported from households being from among individuals who were 15 years or older. The second most affected group was the age group between 5 and 14 years followed by children aged under 5, with 31% and 14% burden, respectively.
CONCLUSION: Despite the achievement of universal coverage in terms of LLINs access, utilization of vector control interventions in the area remained low. Using bed nets for unintended purposes remained a major challenge. Therefore, continued community education and communication work should be prioritized in the study area to bring about the desired behavioural changes.

Keywords:  Behavioral change; Control strategy; Ethiopia; Malaria knowledge; Malaria prevalence

DOI:  https://doi.org/10.1186/s12936-021-03996-5
Malar J. 2021 Dec 07. 20(1): 458

Civilian-military malaria outbreak response in Thailand: an example of multi-stakeholder engagement for malaria elimination.

Michelle E Roh, Kanyarat Lausatianragit, Nithinart Chaitaveep, Krisada Jongsakul, Prayuth Sudathip, Chatree Raseebut, Sutchana Tabprasit, Prasert Nonkaew, Michele Spring, Montri Arsanok, Parat Boonyarangka, Sabaithip Sriwichai, Piyaporn Sai-Ngam, Chaiyaporn Chaisatit, Peerapol Pokpong, Preecha Prempree, Sara Rossi, Mitra Feldman, Mariusz Wojnarski, Adam Bennett, Roly Gosling, Danai Jearakul, Wanchai Lausatianragit, Philip L Smith, Nicholas J Martin, Andrew A Lover, Mark M Fukuda.

  BACKGROUND: In April 2017, the Thai Ministry of Public Health (MoPH) was alerted to a potential malaria outbreak among civilians and military personnel in Sisaket Province, a highly forested area bordering Cambodia. The objective of this study was to present findings from the joint civilian-military outbreak response.METHODS: A mixed-methods approach was used to assess risk factors among cases reported during the 2017 Sisaket malaria outbreak. Routine malaria surveillance data from January 2013 to March 2018 obtained from public and military medical reporting systems and key informant interviews (KIIs) (n = 72) were used to develop hypotheses about potential factors contributing to the outbreak. Joint civilian-military response activities included entomological surveys, mass screen and treat (MSAT) and vector control campaigns, and scale-up of the "1-3-7" reactive case detection approach among civilians alongside a pilot "1-3-7" study conducted by the Royal Thai Army (RTA).
RESULTS: Between May-July 2017, the monthly number of MoPH-reported cases surpassed the epidemic threshold. Outbreak cases detected through the MoPH mainly consisted of Thai males (87%), working as rubber tappers (62%) or military/border police (15%), and Plasmodium vivax infections (73%). Compared to cases from the previous year (May-July 2016), outbreak cases were more likely to be rubber tappers (OR = 14.89 [95% CI: 5.79-38.29]; p < 0.001) and infected with P. vivax (OR=2.32 [1.27-4.22]; p = 0.006). Themes from KIIs were congruent with findings from routine surveillance data. Though limited risk factor information was available from military cases, findings from RTA's "1-3-7" study indicated transmission was likely occurring outside military bases. Data from entomological surveys and MSAT campaigns support this hypothesis, as vectors were mostly exophagic and parasite prevalence from MSAT campaigns was very low (range: 0-0.7% by PCR/microscopy).
CONCLUSIONS: In 2017, an outbreak of mainly P. vivax occurred in Sisaket Province, affecting mainly military and rubber tappers. Vector control use was limited to the home/military barracks, indicating that additional interventions were needed during high-risk forest travel periods. Importantly, this outbreak catalyzed joint civilian-military collaborations and integration of the RTA into the national malaria elimination strategy (NMES). The Sisaket outbreak response serves as an example of how civilian and military public health systems can collaborate to advance national malaria elimination goals in Southeast Asia and beyond.

Keywords:  Civilian; Civilian-military cooperation; Greater Mekong Subregion; Malaria; Malaria elimination; Malaria outbreak investigation; Military; Southeast Asia; Thailand

DOI:  https://doi.org/10.1186/s12936-021-03995-6
BMJ Glob Health. 2021 Dec;pii: e005815. [Epub ahead of print]6(12):

Four decades of epidemiological data reveal trajectories towards malaria elimination in Kheda district (Gujarat), western part of India.

Rajendra Kumar Baharia, Chander Prakash Yadav, Amit Sharma.

  BACKGROUND: Malaria is a main public health problem in India and was so particularly in the state of Gujarat in the western part of the country. This study assesses the effects of various interventions on malaria cases using data from the last 33 years (1987-2019).METHODS: Here we have analysed 33 years of malaria epidemiological data from a malaria clinic in Kheda district in Gujarat. The data were digitised yearly and monthly, age-wise and gender-wise, and descriptive analysis was performed to assess the effects of several interventions on malaria burden.
RESULTS: During 1987-2019, our clinic diagnosed 5466 Plasmodium vivax and 4732 P. falciparum malaria cases. Overall, there was a declining trend in malaria cases except for the years 1991, 1994, 2004 and 2005. The year 2004 especially witnessed an epidemic in Kheda as well as throughout Gujarat. Malaria infections were most common (40%) among the 21-40 years age group. Fever was the most common symptom in all age groups.
INTERPRETATION: Introduction of revised drug policy and improved surveillance technique (rapid diagnosis kits) have strengthened the diagnosis and treatment of malaria in the district. Use of pyrethroid in indoor residual insecticide spray has also strengthened vector control. Among the various interventions used, long-lasting insecticide nets and introduction of artemisinin-based combination therapy have played significant roles in controlling malaria cases. A more drastic decline in P. falciparum cases versus P. vivax is evident, but the latter persists in high proportions and therefore new tools for malaria control will be needed for elimination.

Keywords:  epidemiology; indices of health and disease and standardisation of rates; malaria

DOI:  https://doi.org/10.1136/bmjgh-2021-005815
Math Biosci. 2021 Dec 06. pii: S0025-5564(21)00154-1. [Epub ahead of print] 108750

Using observed incidence to calibrate the transmission level of a mathematical model for Plasmodium vivax dynamics including case management and importation.

Clara Champagne, Maximilian Gerhards, Justin Lana, Bernardo García Espinosa, Christina Bradley, Oscar González, Justin M Cohen, Arnaud Le Menach, Michael T White, Emilie Pothin.

  In this work, we present a simple and flexible model for Plasmodium vivax dynamics which can be easily combined with routinely collected data on local and imported case counts to quantify transmission intensity and simulate control strategies. This model extends the model from White et al. (2016) by including case management interventions targeting liver-stage or blood-stage parasites, as well as imported infections. The endemic steady state of the model is used to derive a relationship between the observed incidence and the transmission rate in order to calculate reproduction numbers and simulate intervention scenarios. To illustrate its potential applications, the model is used to calculate local reproduction numbers in Panama and identify areas of sustained malaria transmission that should be targeted by control interventions.

Keywords:  Malaria model; Panama; Plasmodium vivax model; Plasmodium vivax radical cure

DOI:  https://doi.org/10.1016/j.mbs.2021.108750
Int J Environ Res Public Health. 2021 Dec 03. pii: 12784. [Epub ahead of print]18(23):

Epidemiological Trends of Malaria in Five Years and under Children of Nsanje District in Malawi, 2015-2019.

Theodore Gondwe, Yongi Yang, Simeon Yosefe, Maisa Kasanga, Griffin Mulula, Mphatso Prince Luwemba, Annie Jere, Victor Daka, Tobela Mudenda.

  BACKGROUND: Malaria continues to be a major public health problem in Malawi and the greatest load of mortality and morbidity occurs in children five years and under. However, there is no information yet regarding trends and predictions of malaria incidence in children five years and under at district hospital level, particularly at Nsanje district hospital.AIM: Therefore, this study aimed at investigating the trends of malaria morbidity and mortality in order to design appropriate interventions on the best approach to contain the disease in the near future.
METHODOLOGY: Trend analysis of malaria morbidity and mortality together with time series analysis using the SARIMA (Seasonal Autoregressive Integrated Moving Average) model was used to predict malaria incidence in Nsanje district.
RESULTS: The SARIMA model used malaria cases from 2015 to 2019 and created the best model to forecast the malaria cases in Nsanje from 2020 to 2022. An SARIMA (0, 1, 2) (0,1,1)12 was suitable for forecasting the incidence of malaria for Nsanje.
CONCLUSION: The mortality and morbidity trend showed that malaria cases were growing at a fluctuating rate at Nsanje district hospital. The relative errors between the actual values and predicted values indicated that the predicted values matched the actual values well. Therefore, the model proved that it was adequate to forecast monthly malaria cases and it had a good fit, hence, was appropriate for this study.

Keywords:  SARIMA; malaria incidence; time series

DOI:  https://doi.org/10.3390/ijerph182312784
Front Genet. 2021 ;12 676960

Insilico Functional Analysis of Genome-Wide Dataset From 17,000 Individuals Identifies Candidate Malaria Resistance Genes Enriched in Malaria Pathogenic Pathways.

Delesa Damena, Francis E Agamah, Peter O Kimathi, Ntumba E Kabongo, Hundaol Girma, Wonderful T Choga, Lemu Golassa, Emile R Chimusa.

  Recent genome-wide association studies (GWASs) of severe malaria have identified several association variants. However, much about the underlying biological functions are yet to be discovered. Here, we systematically predicted plausible candidate genes and pathways from functional analysis of severe malaria resistance GWAS summary statistics (N = 17,000) meta-analysed across 11 populations in malaria endemic regions. We applied positional mapping, expression quantitative trait locus (eQTL), chromatin interaction mapping, and gene-based association analyses to identify candidate severe malaria resistance genes. We further applied rare variant analysis to raw GWAS datasets (N = 11,000) of three malaria endemic populations including Kenya, Malawi, and Gambia and performed various population genetic structures of the identified genes in the three populations and global populations. We performed network and pathway analyses to investigate their shared biological functions. Our functional mapping analysis identified 57 genes located in the known malaria genomic loci, while our gene-based GWAS analysis identified additional 125 genes across the genome. The identified genes were significantly enriched in malaria pathogenic pathways including multiple overlapping pathways in erythrocyte-related functions, blood coagulations, ion channels, adhesion molecules, membrane signalling elements, and neuronal systems. Our population genetic analysis revealed that the minor allele frequencies (MAF) of the single nucleotide polymorphisms (SNPs) residing in the identified genes are generally higher in the three malaria endemic populations compared to global populations. Overall, our results suggest that severe malaria resistance trait is attributed to multiple genes, highlighting the possibility of harnessing new malaria therapeutics that can simultaneously target multiple malaria protective host molecular pathways.

Keywords:  functional analysis; genes; genome-wide association study; pathways; severe malaria

DOI:  https://doi.org/10.3389/fgene.2021.676960