bims-mosdis 2022-02-06 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2022–02–06
twenty papers selected by
Richard Halfpenny, Staffordshire University

Cemeteries as sources of Aedes aegypti and other mosquito species in southeastern Puerto Rico.
Water quality characteristics of breeding habitats in relation to the density of Aedes aegypti and Aedes albopictus in domestic settings in Gampaha District of Sri Lanka.
Parous rate and longevity of anophelines mosquitoes in bure district, northwestern Ethiopia.
Population Fluctuations and Abundance Indices of Mosquitoes (Diptera: Culicid), as the Potential Bridge Vectors of Pathogens to Humans and Animals in Mazandaran Province, Northern Iran.
Resistance Status of Anopheles maculipennis and Anopheles superpictus to the Conventional Insecticides in Northeastern Caspian Littoral, Iran.
Monitoring insecticide resistance of adult and larval Aedes aegypti (Diptera: Culicidae) in Phnom Penh, Cambodia.
Malaria prevention interventions beyond long-lasting insecticidal nets and indoor residual spraying in low- and middle-income countries: a scoping review.
Current Status of Insecticide Susceptibility in the Principal Malaria Vector, Anopheles gambiae in Three Northern States of Nigeria.
Bloodmeal regulation in mosquitoes curtails dehydration-induced mortality, altering vectorial capacity.
Vector control strategies in Brazil: a qualitative investigation into community knowledge, attitudes and perceptions following the 2015-2016 Zika virus epidemic.
Detection of Mayaro virus in Aedes aegypti mosquitoes circulating in Goiânia-Goiás-Brazil.
Enhanced Excito-Repellency of Binary Mixtures of Plant-Based Mosquito Repellents Against Culex quinquefasciatus Say (Diptera: Culicidae), a Night Biting Mosquito Species.
Spatial patterns of West Nile virus distribution in the Volgograd region of Russia, a territory with long-existing foci.
Current knowledge of vector-borne zoonotic pathogens in Zambia: A clarion call to scaling-up "One Health" research in the wake of emerging and re-emerging infectious diseases.
Effects of climate variability and environmental factors on the spatiotemporal distribution of malaria incidence in the Amhara national regional state, Ethiopia.
The olfactory gating of visual preferences to human skin and visible spectra in mosquitoes.
Burden of malaria, impact of interventions and climate variability in Western Ethiopia: an area with large irrigation based farming.
Constructing and validating a transferable epidemic risk index in data scarce environments using open data: A case study for dengue in the Philippines.
The influence of landscape structure on the dispersal pattern of yellow fever virus in the state of São Paulo.
Impact of extractive industries on malaria prevalence in the Democratic Republic of the Congo: a population-based cross-sectional study.

Trop Med Int Health. 2022 Feb 03.

Cemeteries as sources of Aedes aegypti and other mosquito species in southeastern Puerto Rico.

Luisa M Otero, Gisela Medina-Martinez, Manuel Sepúlveda, Verónica Acevedo, Mayra Toro, Roberto Barrera.

   OBJECTIVE: To investigate the presence and abundance of mosquito species in containers found in different types of cemeteries in Puerto Rico to assess their importance and make control recommendations.
METHODS: We conducted surveys of containers with water in 16 cemeteries in southeastern Puerto Rico to: detect the presence of larvae and pupae of Aedes aegypti and other mosquitoes; identify the most common and productive containers and study their variation in relation to the type of cemetery.
RESULTS: The most common containers with water were flowerpots, followed in abundance by a variety of discarded containers and open tombs. We found a positive relationship between density of containers with water and rainfall. There was a rich community of mosquito species developing in containers of the inspected cemeteries: nine mosquito species belonging to four genera with Ae. aegypti and Ae. mediovittatus being the most frequent and abundant. We sampled 13 cement type cemeteries, 2 mixed, and only 1 lawn cemetery, consequently we could not draw any conclusion regarding container productivity and cemetery type.
CONCLUSIONS: Surveyed cemeteries were important sources of Ae. aegypti and other mosquitoes in flowerpots, discarded containers, and open tombs. We recommend conducting further studies to establish how frequently inspections should occur; and mosquito control by emptying aquatic habitats and larviciding to reduce mosquito productivity and protect workers and visitors from mosquito bites and possible transmission of arboviruses.

Keywords:   Aedes aegypti ; Puerto Rico; cemeteries; flowerpots; mosquito control

DOI:  https://doi.org/10.1111/tmi.13723
Acta Trop. 2022 Jan 31. pii: S0001-706X(22)00038-9. [Epub ahead of print] 106339

Water quality characteristics of breeding habitats in relation to the density of Aedes aegypti and Aedes albopictus in domestic settings in Gampaha District of Sri Lanka.

Rasika Dalpadado, Deepika Amarasinghe, Nayana Gunathilaka.

  In spite of the unavailability of measures to target dengue control in human populations, the promising way of combating the disease is by controlling vector mosquito larvae and their breeding habitats. Water quality characteristics of the breeding habitats of dengue vectors are among the crucial parameters that determine the female mosquito's oviposition and breeding. Therefore, a cross-sectional study was conducted to investigate the habitat characteristics of dengue vector mosquitoes by assessing the water quality of positive breeding habitats using the weighted arithmetic water quality index (WQI). The present study was conducted in domestic areas of the selected medical officer of health areas of the Gampaha district, Sri Lanka, from 2017 to 2019. Water quality characteristics of breeding habituations were measured and analysed. The relationship between water quality parameters in breeding habitats with the occurrence of mosquito species was assessed using Kruskal-Wallis one-way analysis of variance, followed by pairwise comparison using Dunn's test and Mann-Whitney U test at a 5% level of significance. This study revealed that the temperature of Aedes mosquito breeding water ranged between 25.3 and 39.8 °C, and bred at temperatures as high as 39.8 °C in discarded receptacles. The results indicated that Ae. aegypti was prominent in alkaline water ranging between 7.5 and 8.5 pH, whereas Ae. albopictus was abundant in water with a pH range of 6.5-7.5. Both species of Aedes inhabited waters of low turbidity and TDS level. Ae. aegypti and Ae. albopictus immatures were prominent in water where TDS levels ranged between 250 and 350 ppm. The mean conductivity in the mosquito breeding water was recorded as 228.3 ± 63.9 µs/cm. The study revealed that Aedes mosquitoes could breed in water with a mean dissolved oxygen level of 6.9 ± 0.7 mg/L, ranging between 6.35 ± 1.09 mg/L and 7.28 ± 0.26 mg/L. The water quality indices were calculated for the eight previously identified breeding habitat categories of Aedes mosquitoes.

Keywords:  breeding; dengue vectors; mosquito; water quality index

DOI:  https://doi.org/10.1016/j.actatropica.2022.106339
PLoS One. 2022 ;17(2): e0263295

Parous rate and longevity of anophelines mosquitoes in bure district, northwestern Ethiopia.

Tilahun Adugna, Emana Getu, Delenasaw Yewhelew.

The intensity of malaria transmission is measured by parous rate, daily survival rate, human blood meal frequency, sporozoite rate, and entomological inoculation rates. Female parous status is a key index of vector competence, adult vector longevity, recruitment rate of adult, and the length of a gonotrophic cycle. Hence, the present study was aimed to investigate the parous rate and the longevity of Anopheles mosquitoes in Bure District, Northwestern Ethiopia. Parous rate was estimated as the number of mosquitoes with parous ovaries divided by the number of females dissected multiplied by 100. Mosquito life expectancy (longevity as d) was estimated by. One way- ANOVA was applied to confirm the presence of parous rate difference in the villages (p < 0.05). A total of 952 unfed hosts-seeking Anopheles mosquitoes was dissected for parous rate determination. The overall parous rate of An. arabiensis in the district was 52.0%, and the highest parous rate was recorded in Shnebekuma than other villages (F 2, 33 = 6.974; p = 0.003). Similarly, the parous rate of An. cinereus showed significant variation among villages (F 2, 33 = 5.044, p = 0.012) and the highest rate (63.0%) was recorded in Bukta. The mean longevity of An. funestus, An. arabiensis, An. coustani, An. squamosus, An. pharoensis, and An. cinereus was 6.5 days, 4.6 days, 3.5 days, 3.7 days, 2.7 days, and 2.2 days, respectively. The longevity of each species was not sufficient to complete the life cycle of malaria parasite for malaria transmission throughout the year because P. falciparum requires from 12-14 day.

DOI: https://doi.org/10.1371/journal.pone.0263295
J Arthropod Borne Dis. 2021 Jun;15(2): 207-224

Population Fluctuations and Abundance Indices of Mosquitoes (Diptera: Culicid), as the Potential Bridge Vectors of Pathogens to Humans and Animals in Mazandaran Province, Northern Iran.

Seyed Hassan Nikookar, Mahmoud Fazeli-Dinan, Ahmadali Enayati.

   Background: Seasonal activity patterns of mosquitoes are essential as baseline knowledge to understand the transmission dynamics of vector-borne diseases. This study was conducted to evaluate the monthly dynamics of the mosquito populations and their relation to meteorological factors in Mazandaran Province, north of Iran.
Methods: Mosquito adults and larvae were collected from 16 counties of Mazandaran Province using different sampling techniques, once a month from May to December 2014. "Index of Species Abundance" (ISA) along with "Standardized ISA" (SISA) was used for assessing the most abundant species of mosquitoes based on the explanations of Robert and Hsi. Pearson's correlation coefficient (R) was used to assess the relationships between the monthly population fluctuations and meteorological variables.
Results: Overall, 23750 mosquitoes belonging to four genera and nineteen species were collected and identified. The highest population density of mosquitoes was in July and the lowest in May. The ISA/SISA indices for Culex pipiens were both 1 for larvae and 1.25/0.973 for adults in total catch performed in human dwellings. For Cx. tritaeniorhynchus, the ISA/SISA were 1.68/0.938 in pit shelter method. A significant positive correlation was observed between population fluctuations of Cx. tritaeniorhynchus and mean temperature (R: 0.766, P< 0.027).
Conclusion: The results indicated that the mosquitoes are more active in July, and Cx. pipiens and Cx. tritaeniorhynchus were the most abundant species. Considering the potential of these species as vectors of numerous pathogens, control programs can be planed based on their monthly activity pattern in the area.

Keywords:  Abundance indices; Caspian Sea littoral; Mazandaran; Mosquitoes; Seasonal activity

DOI:  https://doi.org/10.18502/jad.v15i2.7490
J Arthropod Borne Dis. 2021 Jun;15(2): 171-178

Resistance Status of Anopheles maculipennis and Anopheles superpictus to the Conventional Insecticides in Northeastern Caspian Littoral, Iran.

Aioub Sofizadeh, Mohammad Reza Abai, Hassan Vatandoost, Ahmad Raeisi, Mohammad Sistanizadeh-Aghdam.

   Background: Malaria resurgence has occurred in the northern half parts of Iran. The resurgence of malaria in the prone area could arise from various factors, e.g. wide use of pesticides in the agriculture sector and factors such as habitual patterns of movement of local people from problematic southeastern foci in Iran toward the Caspian Littoral. There are no new data on the resistance status of main malaria vectors in the Caspian Littoral, and this study was aimed at renewal data on conventional insecticides.
Methods: The field strain of adult Anopheles superpictus and Anopheles maculipennis were collected using the hand catch method and transferred to the laboratory. The susceptibility tests were carried out against DDT 4%, Malathion 5%, Permethrin 0.75%, Deltamethrin 0.05%, and Lambda-cyhalothrin 0.05%, followed by the WHO's procedure.
Results: The primary malaria vector in Caspian Littoral is An. maculipennis, revealed to be still resistant to DDT and mortality rate, LT50 and LT90 of female mosquitoes were 75.0%, 54.2, minutes and 111.3 minutes. The under 'verification required' status of An. maculipennis was also revealed to Lambda-cyhalothrin based on recent WHO's criteria. The malaria vector An. superpictus is also considered the second malaria vectors in the west parts of the studied area, which showed to be susceptible to all insecticides tested.
Conclusion: DDT resistance is persisted in An. maculipennis despite stopping residual spraying with DDT since 1978 in the Caspian Littoral, but the occurrence of pyrethroid under 'verification required' status is a progressive threat to the possible development of cross-resistance in the future.

Keywords:  Anopheles maculipennis; Anopheles superpictus; Caspian littoral; Insecticide resistance; Malaria

DOI:  https://doi.org/10.18502/jad.v15i2.7486
Parasit Vectors. 2022 Jan 31. 15(1): 44

Monitoring insecticide resistance of adult and larval Aedes aegypti (Diptera: Culicidae) in Phnom Penh, Cambodia.

Sebastien Boyer, Pierre-Olivier Maquart, Kalyan Chhuoy, Kimhuor Suor, Moeun Chhum, Kimly Heng, Sokkeang Leng, Didier Fontenille, Sebastien Marcombe.

BACKGROUND: Dengue fever is a major public health concern in Cambodia, with thousands of cases every year in urban, suburban and rural areas of the country. The main vector of dengue fever in Cambodia is Aedes aegypti. The organophosphate larvicide temephos and adulticides belonging to the pyrethroid family have been widely used for decades by public health authorities to fight dengue vectors, but resistance of Ae. aegypti to these insecticides has been previously described for Cambodia.
METHODS: In order to adapt the vector control strategy presently used in Cambodia, we tested 14 adulticides belonging to the carbamate, organochlorine, organophosphate, and pyrethroid insecticide families and three larvicides [temephos, spinosad and Bacillus thuringiensis ser. israelensis (Bti)] belonging to three different insecticide families (organophosphates, spinosyns and entomopathogenic bacteria). The standard procedures used here to test the adults and larvae of an Ae. aegypti population from Phnom Penh followed World Health Organization guidelines.
RESULTS: For adults, high mortality rates were observed with carbamate, organophosphate and organochlorine (with the exception of dichlorodiphenyltrichloroethane) insecticides (i.e. between 87.6 and 100%), while low mortality rates were observed with all of the tested pyrethroid insecticides (i.e. between 1 and 35%). For larvae, no resistance against Bti was detected [resistance ratio (RR90 < 1.6)], but moderate resistance was observed for temephos and spinosad (RR90 < 5.6).
CONCLUSIONS: The results of this study indicate that (i) Bti should be considered a serious alternative to temephos for the control of Ae. aegypti larvae; and (ii) the carbamate adulticides propoxur and bendiocarb should be employed instead of the widely used pyrethroid insecticides for the control of adult Ae. aegypti on land under mosaic farming and crop rotation in Cambodia, as the insects were found to be resistant to the latter types of insecticide. Research focusing on insecticide resistance and innovative and effective vector control strategies should be undertaken as a public health priority in Cambodia.

DOI: https://doi.org/10.1186/s13071-022-05156-3
Malar J. 2022 Feb 02. 21(1): 31

Malaria prevention interventions beyond long-lasting insecticidal nets and indoor residual spraying in low- and middle-income countries: a scoping review.

Sarah Nalinya, David Musoke, Kevin Deane.

   BACKGROUND: Significant progress in malaria prevention during the past two decades has prompted increasing global dialogue on malaria elimination. Recent reviews on malaria strategies have focused mainly on long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), with little emphasis on other prevention methods. This article is a scoping review of literature on malaria prevention methods beyond LLINs and IRS in low- and middle-income countries (LMICs).
METHODS: This scoping review found articles published between from 1994 to 2020. Studies were obtained from a search of the PubMed, the Cochrane Library and Social Science abstracts. Grey literature and manual search of secondary references was also done. The search strategy included all study designs but limited only to English. Three independent reviewers performed the selection and characterization of articles, and the data collected were synthesized qualitatively.
RESULTS: A total of 10,112 studies were identified among which 31 met the inclusion criteria. The results were grouped by the 3 emerging themes of: housing design; mosquito repellents; and integrated vector control. Housing design strategies included closing eves, screening of houses including windows, doors and ceilings, while mosquito repellents were mainly spatial repellents, use of repellent plants, and use of plant-based oils. Integrated vector control included larvae source management. Evidence consistently shows that improving housing design reduced mosquito entry and malaria prevalence. Spatial repellents also showed promising results in field experiments, while evidence on repellent plants is limited and still emerging. Recent literature shows that IVM has been largely ignored in recent years in many LMICs. Some malaria prevention methods such as spatial repellents and IVM are shown to have the potential to target both indoor and outdoor transmission of malaria, which are both important aspects to consider to achieve malaria elimination in LMICs.
CONCLUSION: The scoping review shows that other malaria prevention strategies beyond LLINs and IRS have increasingly become important in LMICs. These methods have a significant role in contributing to malaria elimination in endemic countries if they are adequately promoted alongside other conventional approaches.

Keywords:  Housing design; Integrated vector management; LMICs; Malaria; Mosquitoes; Preventive interventions; Repellents

DOI:  https://doi.org/10.1186/s12936-022-04052-6
J Arthropod Borne Dis. 2021 Jun;15(2): 196-206

Current Status of Insecticide Susceptibility in the Principal Malaria Vector, Anopheles gambiae in Three Northern States of Nigeria.

Mustapha Ahmed Yusuf, Mohammad Ali Oshaghi, Hassan Vatandoost, Ahmad Ali Hanafi-Bojd, Ahmadali Enayati, Rabiu Ibrahim Jalo, Akande Oyebanji Azeez Aliyu Aminu, Isa Muhammad Daneji.

   Background: Malaria is a major public health problem in Nigeria with 97% of its population with high morbidity and mortality. Mosquitoes play an important role in the transmission of malaria parasites. This study was conducted to evaluate the current resistance status of Anopheles gambiae to insecticides.
Methods: Larvae of An. gambiae was collected from three zones; A, B and C differentiated on the basis of variation in agricultural ecosystems between August and November, 2018 in the northeast and northwestern parts of Nigeria. They were carefully reared to adult stage and insecticidal susceptibility tests were conducted.
Results: The mosquitoes tested showed high levels of resistance to all the insecticides used with the exception of malathion. Study zone A, recorded 74% mortality after 24h to deltamethrin compared to 81% from zone B and 82% from zone C, respectively. Mosquitoes from zone B exposed to DDT had the highest level of resistance at 37% compared to 40% and 53% from zones A and C, respectively. Resistant to bendiocarb was also observed, with zone A having the lowest mortality of 44% compared to 48% from zone C and 55% from Zone B, respectively. According to the results of knockdown tests, mosquitoes from Zone A exposed to deltamethrin recorded the lowest knockdown across the study locations while zone B recorded the lowest knockdown for DDT.
Conclusion: The results of the study provide an insight into the current status of An. gambiae to four major insecticides in northern Nigeria as guideline for mosquitocontrol.

Keywords:  Anopheles gambiae; Insecticide resistance; Malaria; Northern Nigeria; Susceptibility

DOI:  https://doi.org/10.18502/jad.v15i2.7489
J Insect Physiol. 2022 Feb 01. pii: S0022-1910(22)00009-9. [Epub ahead of print] 104363

Bloodmeal regulation in mosquitoes curtails dehydration-induced mortality, altering vectorial capacity.

Christopher J Holmes, Elliott Brown, Dhriti Sharma, Quynh Nguyen, Austin Spangler, Atit Pathak, Blaine Payton, Matthew Warden, Ashay J Shah, Samantha Shaw, Joshua B Benoit.

  Mosquitoes readily lose water when exposed to any humidity less than that of near saturated air unless mitigated, leading to shifts in behavior, survival, distribution, and reproduction. In this study, we conducted a series of physiological experiments on two prominent species in the Culicinae subfamily: Culex pipiens, a vector of West Nile virus, and Aedes aegypti, a vector of yellow fever and Zika to examine the effects of dehydration. We exposed C. pipiens and A. aegypti to non-dehydrating conditions (saturated air), dehydrating conditions (air at a 0.89 kPa saturation vapor pressure deficit), several recovery conditions, as well as to bloodfeeding opportunities. We show that dehydrated mosquitoes increase bloodfeeding propensity, improve retention, and decrease excretion of a post-dehydration bloodmeal. In addition, mosquitoes that take a bloodmeal prior to dehydration exposure show increased survival over non-bloodfed counterparts. Dehydration-induced alterations in survival, reproduction, and bloodfeeding propensity of C. pipiens and A. aegypti resulted in marked changes to vectorial capacity. Ultimately, these results become increasingly important as drought intensifies in association with climate change and mosquitoes become more likely to experience arid periods.

Keywords:  Aedes aegypti; Culex pipiens; bloodfeeding; reproduction; survival; vectorial capacity

DOI:  https://doi.org/10.1016/j.jinsphys.2022.104363
BMJ Open. 2022 Jan 31. 12(1): e050991

Vector control strategies in Brazil: a qualitative investigation into community knowledge, attitudes and perceptions following the 2015-2016 Zika virus epidemic.

Dani Bancroft, Grace M Power, Robert T Jones, Eduardo Massad, Jorge Bernstein Iriat, Raman Preet, John Kinsman, James G Logan.

   OBJECTIVE: The World Health Organization declared a Public Health Emergency of International Concern following the rapid emergence of neonatal microcephaly in Brazil during the 2015-2016 Zika virus (ZIKV) epidemic. In response, a national campaign sought to control Aedes mosquito populations and reduce ZIKV transmission. Achieving adherence to vector control or mosquito-bite reduction behaviours, including the use of topical mosquito repellents, is challenging. Coproduction of research at the community level is needed to understand and mitigate social determinants of lower engagement with Aedes preventive measures, particularly within disempowered groups.
DESIGN: In 2017, the Zika Preparedness Latin America Network (ZikaPLAN) conducted a qualitative study to understand individual and community level experiences of ZIKV and other mosquito-borne disease outbreaks. Presented here is a thematic analysis of 33 transcripts from community focus groups and semistructured interviews, applying the Health Belief Model (HBM) to elaborate knowledge, attitudes and perceptions of ZIKV and vector control strategies.
PARTICIPANTS: 120 purposively sampled adults of approximate reproductive age (18-45); 103 women participated in focus groups and 17 men in semistructured interviews.
SETTING: Two sociopolitically and epidemiologically distinct cities in Brazil: Jundiaí (57 km north of São Paolo) and Salvador (Bahia state capital).
RESULTS: Four key and 12 major themes emerged from the analysis: (1) knowledge and cues to action; (2) attitudes and normative beliefs (perceived threat, barriers, benefits and self-efficacy); (3) behaviour change (household prevention and community participation); and (4) community preferences for novel repellent tools, vector control strategies and ZIKV messaging.
CONCLUSIONS: Common barriers to repellent adherence were accessibility, appearance and effectiveness. A strong case is made for the transferability of the HBM to inform epidemic preparedness for mosquito-borne disease outbreaks at the community level. Nationally, a health campaign targeting men is recommended, in addition to local mobilisation of funding to strengthen surveillance, risk communication and community engagement.

Keywords:  entomology; epidemiology; infection control; public health

DOI:  https://doi.org/10.1136/bmjopen-2021-050991
Microbes Infect. 2022 Jan 30. pii: S1286-4579(22)00018-1. [Epub ahead of print] 104948

Detection of Mayaro virus in Aedes aegypti mosquitoes circulating in Goiânia-Goiás-Brazil.

Juliana Santana de Curcio, Silvia Maria Salem-Izacc, Luiz Moreira Pereira Neto, Eliane Blanco Nunes, Carlos Eduardo Anunciação, Elisângela de Paula Silveira-Lacerda.

  The Arboviral diseases are caused by arthropod-borne viruses, such as Mayaro virus (MAYV), the etiological agent of Mayaro fever. This disease has been drawing the attention of the public health authorities for the increased number of cases likely due to virus adaptation for survival to urban areas as well as infection and multiplication in other vectors insects. Therefore, this work aimed to identify the MAYV infecting Aedes aegypti mosquitoes in Goiânia, the capital of state of Goiás, Brazil. For the development of study, the larvae of A. aegypti were collected in Basic Health Units from different regions of Goiânia then the larvae were grown to adult mosquitoes in controlled laboratory conditions. The female mosquitoes were submitted to the procedure of head and body separation. The RNAs obtained from these samples were analyzed by real-time PCR for identification of arboviruses. We only detect the presence of MAVY in the mosquitoes, in this sense our findings suggest that A. aegypti harbor MAYV in different anatomical sites, and potentially the process of vertical transmission of MAYV can occur in this vector.

Keywords:  Latin America; Mayaro virus; arboviruses; disease; vector

DOI:  https://doi.org/10.1016/j.micinf.2022.104948
J Med Entomol. 2022 Jan 30. pii: tjac002. [Epub ahead of print]

Enhanced Excito-Repellency of Binary Mixtures of Plant-Based Mosquito Repellents Against Culex quinquefasciatus Say (Diptera: Culicidae), a Night Biting Mosquito Species.

Wasana Boonyuan, Alex Ahebwa, Jirod Nararak, Sunaiyana Sathantriphop, Theeraphap Chareonviriyaphap.

  Efficacies of essential oils (EOs) of Vetiveria zizanioides (L.) Nash. (Poales: Poaceae) (VZ EO), Cananga odorata (Lam) Hook. F. & Thomson (Magnoliales: Annonaceae) (CO EO), and crude extract (CE) of Andrographis paniculata (Burm.F.) Wall ex. Nees (Lamiales: Acanthaceae) (AP CE), against laboratory (lab) and field strains of Culex quinquefasciatus Say were investigated. Irritant and repellent activities of individual and binary mixtures of plant extracts were compared with N,N-diethyl-m-toluamide (DEET) using an excito-repellency system. The irritant activity (direct tarsal contact), the mean percent escape response of VZ EO (91.67%, 83.33%), and CO EO (80%, 88.33%) were not significantly different compared with DEET (88.33%, 95%) against lab and field strains, respectively. Similarly, irritant responses in combinations (1:1 and 1:2, v:v) of either VZ EO or CO EO with AP CE were not significantly different from DEET against both strains (P > 0.001). The repellent activity (no tarsal contact), the mean percent escape response of VZ EO (68.33%), CO EO (61.67%), and VZ EO+AP CE (1:1, v:v) (81.67%) against lab strain and CO EO (85%) against field strain were not significantly different from that of DEET (P > 0.001). Interestingly, the greatest contact irritancy of VZ EO+AP CE (1:1, v:v) (96.67%) (P = 0.0026) and a stronger repellency response of CO EO (85%) (P = 0.0055) produced significantly different patterns of escape response compared with DEET against both lab and field strains, respectively. The EOs of VZ EO and CO EO or their mixture with AP CE showed potential as plant-based active ingredients for mosquito repellents. In addition, the major chemical constituents of VZ EO were β-vetivone (6.4%), khusimol (2.96%), and α-vetivone (2.94%) by gas chromatograpy-mass spectrometry.

Keywords:   Andrographis paniculata ; Cananga odorata ; Vetiveria zizanioides ; DEET; Excito-Repellency

DOI:  https://doi.org/10.1093/jme/tjac002
PLoS Negl Trop Dis. 2022 Jan;16(1): e0010145

Spatial patterns of West Nile virus distribution in the Volgograd region of Russia, a territory with long-existing foci.

Natalia Shartova, Varvara Mironova, Svetlana Zelikhina, Fedor Korennoy, Mikhail Grishchenko.

Southern Russia remains affected by West Nile virus (WNV). In the current study, we identified the spatial determinants of WNV distribution in an area with endemic virus transmission, with special reference to the urban settings, by mapping probable points of human infection acquisition and points of virus detection in mosquitoes, ticks, birds, and mammals during 1999-2016. The suitability of thermal conditions for extrinsic virus replication was assessed based on the approach of degree-day summation and their changes were estimated by linear trend analysis. A generalized linear model was used to analyze the year-to-year variation of human cases versus thermal conditions. Environmental suitability was determined by ecological niche modelling using MaxEnt software. Human population density was used as an offset to correct for possible bias. Spatial analysis of virus detection in the environment showed significant contributions from surface temperature, altitude, and distance from water bodies. When indicators of location and mobility of the human population were included, the relative impact of factors changed, with roads becoming most important. When the points of probable human case infection were added, the percentage of leading factors changed only slightly. The urban environment significantly increased the epidemic potential of the territory and created quite favorable conditions for virus circulation. The private building sector with low-storey houses and garden plots located in the suburbs provided a connection between urban and rural transmission cycles.

DOI: https://doi.org/10.1371/journal.pntd.0010145
PLoS Negl Trop Dis. 2022 Feb 04. 16(2): e0010193

Current knowledge of vector-borne zoonotic pathogens in Zambia: A clarion call to scaling-up "One Health" research in the wake of emerging and re-emerging infectious diseases.

Benjamin Mubemba, Monicah M Mburu, Katendi Changula, Walter Muleya, Lavel C Moonga, Herman M Chambaro, Masahiro Kajihara, Yongjin Qiu, Yasuko Orba, Kyoko Hayashida, Catherine G Sutcliffe, Douglas E Norris, Philip E Thuma, Phillimon Ndubani, Simbarashe Chitanga, Hirofumi Sawa, Ayato Takada, Edgar Simulundu.

BACKGROUND: Although vector-borne zoonotic diseases are a major public health threat globally, they are usually neglected, especially among resource-constrained countries, including those in sub-Saharan Africa. This scoping review examined the current knowledge and identified research gaps of vector-borne zoonotic pathogens in Zambia.
METHODS AND FINDINGS: Major scientific databases (Web of Science, PubMed, Scopus, Google Scholar, CABI, Scientific Information Database (SID)) were searched for articles describing vector-borne (mosquitoes, ticks, fleas and tsetse flies) zoonotic pathogens in Zambia. Several mosquito-borne arboviruses have been reported including Yellow fever, Ntaya, Mayaro, Dengue, Zika, West Nile, Chikungunya, Sindbis, and Rift Valley fever viruses. Flea-borne zoonotic pathogens reported include Yersinia pestis and Rickettsia felis. Trypanosoma sp. was the only tsetse fly-borne pathogen identified. Further, tick-borne zoonotic pathogens reported included Crimean-Congo Haemorrhagic fever virus, Rickettsia sp., Anaplasma sp., Ehrlichia sp., Borrelia sp., and Coxiella burnetii.
CONCLUSIONS: This study revealed the presence of many vector-borne zoonotic pathogens circulating in vectors and animals in Zambia. Though reports of human clinical cases were limited, several serological studies provided considerable evidence of zoonotic transmission of vector-borne pathogens in humans. However, the disease burden in humans attributable to vector-borne zoonotic infections could not be ascertained from the available reports and this precludes the formulation of national policies that could help in the control and mitigation of the impact of these diseases in Zambia. Therefore, there is an urgent need to scale-up "One Health" research in emerging and re-emerging infectious diseases to enable the country to prepare for future epidemics, including pandemics.

DOI: https://doi.org/10.1371/journal.pntd.0010193
Spat Spatiotemporal Epidemiol. 2022 Feb;pii: S1877-5845(21)00073-3. [Epub ahead of print]40 100475

Effects of climate variability and environmental factors on the spatiotemporal distribution of malaria incidence in the Amhara national regional state, Ethiopia.

Teshager Zerihun Nigussie, Temesgen Zewotir, Essey Kebede Muluneh.

  Malaria is a severe public health problem in the Amhara region, Ethiopia. A retrospective study was conducted to model and interpret the effects of climate variability and environmental factors on the monthly malaria surveillance data of 152 districts in the region. The data were analyzed using the Bayesian generalized Poisson spatiotemporal model. Malaria incidence had significant seasonal, temporal, and spatial variations in the region. The risk of malaria incidence was decreased by 24% per 100 m increase in altitude. Monthly minimum temperature decreases the risk of malaria by 2.2% per a 1°C increment. The risk of malaria transmission was increased by 8% per 100 mm rise in the total monthly rainfall of districts. Besides, long-lasting insecticidal net coverage significantly reduces malaria risk by a factor of 0.8955. The finding suggests that malaria transmission was higher in northern and western districts. Hence, concerned bodies should consider seasonal, temporal, and spatial variations and effects of climate and environmental factors for intervention and elimination.

Keywords:  Bayesian hierarchical model; Long-lasting insecticide net; Overdispersion; Random effect; Seasonal effect; Spatial structure

DOI:  https://doi.org/10.1016/j.sste.2021.100475
Nat Commun. 2022 Feb 04. 13(1): 555

The olfactory gating of visual preferences to human skin and visible spectra in mosquitoes.

Diego Alonso San Alberto, Claire Rusch, Yinpeng Zhan, Andrew D Straw, Craig Montell, Jeffrey A Riffell.

Mosquitoes track odors, locate hosts, and find mates visually. The color of a food resource, such as a flower or warm-blooded host, can be dominated by long wavelengths of the visible light spectrum (green to red for humans) and is likely important for object recognition and localization. However, little is known about the hues that attract mosquitoes or how odor affects mosquito visual search behaviors. We use a real-time 3D tracking system and wind tunnel that allows careful control of the olfactory and visual environment to quantify the behavior of more than 1.3 million mosquito trajectories. We find that CO2 induces a strong attraction to specific spectral bands, including those that humans perceive as cyan, orange, and red. Sensitivity to orange and red correlates with mosquitoes' strong attraction to the color spectrum of human skin, which is dominated by these wavelengths. The attraction is eliminated by filtering the orange and red bands from the skin color spectrum and by introducing mutations targeting specific long-wavelength opsins or CO2 detection. Collectively, our results show that odor is critical for mosquitoes' wavelength preferences and that the mosquito visual system is a promising target for inhibiting their attraction to human hosts.

DOI: https://doi.org/10.1038/s41467-022-28195-x
BMC Public Health. 2022 Jan 29. 22(1): 196

Burden of malaria, impact of interventions and climate variability in Western Ethiopia: an area with large irrigation based farming.

Werissaw Haileselassie, Daniel M Parker, Behailu Taye, Randy E David, Endalew Zemene, Ming-Chieh Lee, Daibin Zhong, Guofa Zhou, Tesfahun Alemu, Getnet Tadele, James W Kazura, Cristian Koepfli, Wakgari Deressa, Delenasaw Yewhalaw, Guiyun Yan.

   BACKGROUND: Land use change has increasingly been expanding throughout the world in the past decades. It can have profound effects on the spatial and temporal distribution of vector borne diseases like malaria through ecological and habitat change. Understanding malaria disease occurrence and the impact of prevention interventions under this intense environmental modification is important for effective and efficient malaria control strategy.
METHODS: A descriptive ecological study was conducted by reviewing health service records at Abobo district health office. The records were reviewed to extract data on malaria morbidity, mortality, and prevention and control methods. Moreover, Meteorological data were obtained from Gambella region Meteorology Service Center and National Meteorology Authority head office. Univariate, bivariate and multivariate analysis techniques were used to analyze the data.
RESULTS: For the twelve-year time period, the mean annual total malaria case count in the district was 7369.58. The peak monthly malaria incidence was about 57 cases per 1000 people. Only in 2009 and 2015 that zero death due to malaria was recorded over the past 12 years. Fluctuating pattern of impatient malaria cases occurrence was seen over the past twelve years with an average number of 225.5 inpatient cases. The data showed that there is a high burden of malaria in the district. Plasmodium falciparum (Pf) was a predominant parasite species in the district with the maximum percentage of about 90. There was no statistically significant association between season and total malaria case number (F3,8: 1.982, P:0.195). However, the inter-annual total case count difference was statistically significant (F11,132: 36.305, p < 0001). Total malaria case count had shown two months lagged carry on effect. Moreover, 3 months lagged humidity had significant positive effect on total malaria cases. Malaria prevention interventions and meteorological factors showed statistically significant association with total malaria cases.
CONCLUSION: Malaria was and will remain to be a major public health problem in the area. The social and economic impact of the disease on the local community is clearly pronounced as it is the leading cause of health facility visit and admission including the mortality associated with it. Scale up of effective interventions is quite important. Continuous monitoring of the performance of the vector control tools needs to be done.

Keywords:  Ethiopia; Land use change; Malaria; Prevention Interventions

DOI:  https://doi.org/10.1186/s12889-022-12571-9
PLoS Negl Trop Dis. 2022 Feb 04. 16(2): e0009262

Constructing and validating a transferable epidemic risk index in data scarce environments using open data: A case study for dengue in the Philippines.

Fleur Hierink, Jacopo Margutti, Marc van den Homberg, Nicolas Ray.

Epidemics are among the most costly and destructive natural hazards globally. To reduce the impacts of infectious disease outbreaks, the development of a risk index for infectious diseases can be effective, by shifting infectious disease control from emergency response to early detection and prevention. In this study, we introduce a methodology to construct and validate an epidemic risk index using only open data, with a specific focus on scalability. The external validation of our risk index makes use of distance sampling to correct for underreporting of infections, which is often a major source of biases, based on geographical accessibility to health facilities. We apply this methodology to assess the risk of dengue in the Philippines. The results show that the computed dengue risk correlates well with standard epidemiological metrics, i.e. dengue incidence (p = 0.002). Here, dengue risk constitutes of the two dimensions susceptibility and exposure. Susceptibility was particularly associated with dengue incidence (p = 0.048) and dengue case fatality rate (CFR) (p = 0.029). Exposure had lower correlations to dengue incidence (p = 0.193) and CFR (p = 0.162). Highest risk indices were seen in the south of the country, mainly among regions with relatively high susceptibility to dengue outbreaks. Our findings reflect that the modelled epidemic risk index is a strong indication of sub-national dengue disease patterns and has therefore proven suitability for disease risk assessments in the absence of timely epidemiological data. The presented methodology enables the construction of a practical, evidence-based tool to support public health and humanitarian decision-making processes with simple, understandable metrics. The index overcomes the main limitations of existing indices in terms of construction and actionability.

DOI: https://doi.org/10.1371/journal.pntd.0009262
Acta Trop. 2022 Jan 28. pii: S0001-706X(22)00032-8. [Epub ahead of print]228 106333

The influence of landscape structure on the dispersal pattern of yellow fever virus in the state of São Paulo.

Ramon Wilk-da-Silva, Antônio Ralph Medeiros-Sousa, Gabriel Zorello Laporta, Luis Filipe Mucci, Paula Ribeiro Prist, Mauro Toledo Marrelli.

  Man-made changes to the landscape play a crucial role in altering the epidemiologic patterns of infectious diseases, mainly as a result of pathogen spillover. Sylvatic yellow fever is ideally suited to modeling of this phenomenon as the risk of transmission of the disease as well as its circulation and dispersal are associated with forest fragmentation. In this study we investigated the temporal dispersal pattern of yellow fever virus (YFV) by means of confirmed cases of epizootics in non-human primates in municipalities in the state of São Paulo where there was no recommendation for vaccination in 2017. We analyzed the resistance to dispersal associated with different classes of land use and the geographic distances between the different locations where epizootics were recorded. The model that best explained the temporal dispersal pattern of YFV in the study area indicated that this was influenced by the geographic distance between collection locations and by the permeability of the forest edges (150 m) at the interface with the following core areas: Water, Agricultural, Non-Forest Formation and Forestry. Water, Agricultural, Urban and Forest core areas and the interfaces between the latter two formed important barriers to circulation of the virus. These findings indicate that fragmentation of vegetation tends to decrease the time taken for pathogens to spread, while conservation of forest areas has the opposite effect.

Keywords:  Forest edge; Haemagogus leucocelaenus; Land use; Sylvatic yellow fever

DOI:  https://doi.org/10.1016/j.actatropica.2022.106333
Sci Rep. 2022 Feb 02. 12(1): 1737

Impact of extractive industries on malaria prevalence in the Democratic Republic of the Congo: a population-based cross-sectional study.

Cedar L Mitchell, Mark M Janko, Melchior K Mwandagalirwa, Antoinette K Tshefu, Jessie K Edwards, Brian W Pence, Jonathan J Juliano, Michael Emch.

Extraction of natural resources through mining and logging activities provides revenue and employment across sub-Saharan Africa, a region with the highest burden of malaria globally. The extent to which mining and logging influence malaria transmission in Africa remains poorly understood. Here, we evaluate associations between mining, logging, and malaria in the high transmission setting of the Democratic Republic of the Congo using population-representative malaria survey results and geographic data for environmental features and mining and logging concessions. We find elevated malaria prevalence among individuals in rural areas exposed to mining; however, we also detect significant spatial confounding among locations. Upon correction, effect estimates for mining and logging shifted toward the null and we did not find sufficient evidence to detect an association with malaria. Our findings reveal a complex interplay between mining, logging, space, and malaria prevalence. While mining concessions alone may not drive the high prevalence, unobserved features of mining-exposed areas, such as human migration, changing vector populations, or parasite genetics, may instead be responsible.

DOI: https://doi.org/10.1038/s41598-022-05777-9