Narrative Review on Health-EDRM Primary Prevention Measures for Vector-Borne Diseases

Climate change is expanding the global at-risk population for vector-borne diseases (VBDs). The World Health Organization (WHO) health emergency and disaster risk management (health-EDRM) framework emphasises the importance of primary prevention of biological hazards and its value in protecting against VBDs. The framework encourages stakeholder coordination and information sharing, though there is still a need to reinforce prevention and recovery within disaster management. This keyword-search based narrative literature review searched databases PubMed, Google Scholar, Embase and Medline between January 2000 and May 2020, and identified 134 publications. In total, 10 health-EDRM primary prevention measures are summarised at three levels (personal, environmental and household). Enabling factor, limiting factors, co-benefits and strength of evidence were identified. Current studies on primary prevention measures for VBDs focus on health risk-reduction, with minimal evaluation of actual disease reduction. Although prevention against mosquito-borne diseases, notably malaria, has been well-studied, research on other vectors and VBDs remains limited. Other gaps included the limited evidence pertaining to prevention in resource-poor settings and the efficacy of alternatives, discrepancies amongst agencies’ recommendations, and limited studies on the impact of technological advancements and habitat change on VBD prevalence. Health-EDRM primary prevention measures for VBDs require high-priority research to facilitate multifaceted, multi-sectoral, coordinated responses that will enable effective risk mitigation.

• Details recommendations on VBD prevention and vector control including measures A, B, C, D, E, G, H, I, and J.

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Considerations for the use of human participants in vector biology research: A tool for investigators and regulators Vector-Borne Zoonotic Dis 2015 A Level 5: A research methods tool to guide investigators, as well as scientific and ethical review committee members on vector biology research involving human participation.
• Recommends the wearing of protective clothing to cover parts of exposed skin for HLC participants and minimise risks of potentially infectious vector bites.

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Higher risk of malaria transmission outdoors than indoors by Nyssorhynchus darlingi in riverine communities in the Peruvian Amazon Parasites and Vectors 2019 B Level 4: A cross-sectional study involving four communities to gather baseline information about bionomics of malaria vectors and transmission risk factors in a hyperendemic malaria area of Amazonian Peru.
• Suggests that malaria transmission risk is higher outdoors than indoors in the studied communities.

Risk Factors for Symptomatic and Asymptomatic Chikungunya Infection
Trans R Soc Trop Med Hyg.

2013
A Level 4: A cross-sectional study on the risk factors for symptomatic and asymptomatic chikungunya infection.
• Concludes that being in close proximity to a garbage pile and spending at least eight hours per day outdoors were associated with increased symptomatic and asymptomatic chikungunya infection. • Suggests that individuals aged greater than 58 and with a high level of formal education were less prone to symptomatic chikungunya infections. • Indicates that increased time spent outside at dusk or dawn is a significant risk factor for infection. • Indicates that personal behaviours including the lack of vector-prone area avoidance, outdoor exposure avoidance, protective clothing (long sleeves or long pants) when outdoors and mosquito repellent use when outdoors are associated with increased infection risks. • Indicates that the practising of two or more personal protective behaviour traits was associated with significantly reduced infection risks. • Indicates that source-reduction behaviours including stagnant water drainage and gutter checking and cleaning are associated with decreased infection risks. 32 The global distribution and burden of dengue Nature 2013 B Level 5: A modelling framework mapping global distribution of dengue risk, paired with dengue cohort studies and population surfaces to infer public health burden of dengue in 2010.
• Infers a strong association between high levels of precipitation, high temperature and elevated dengue risk.
Impact of air temperature variation on the ixodid ticks habitat and tick-borne encephalitis incidence in the Russian Arctic: the case of the Komi Republic Int J Circumpolar Health 2017 B Level 5: A study on the relationship between tick-borne encephalitis incidence and changes in different external factors.
• Indicates that the expansion of the range of Ixodes persulcatus contributes to the rise in tickborne encephalitis incidence in recent years. • Concludes with a positive correlation between high air temperature and tick-borne encephalitis incidence, with climate change being a driver of incidence rate growth. 34 The association between temperature, rainfall and humidity with common climate-sensitive infectious diseases in Bangladesh PLoS One 2018 B Level 5: An observational exploratory study on the association between climatesensitive infectious disease occurrence and climate characteristics.
• Infers a strong association between high levels of precipitation, high temperature, high humidity and malaria incidence. • Concludes that long-sleeved clothing and avoiding the sun by seeking shade significantly lower the odds of multiple sunburns.
• Suggests that shade-seeking and wearing of protective clothing may be more effective than sunscreen for protection. 39 Big Book of Self- an attempt to generate recommendations and instructions.
• Suggests that permethrin is another common active ingredient applied to clothing that retains effectiveness for up to six washings. • Indicates that there are alternative 'natural' repellents which are not necessarily safer than DEET or Icaridin and some may not offer adequate protection. • Recommends guidelines on repellent usage such as light application on the basis of it being a chemical which may be harmful if misused. Infants under the age of 6 should be using alternatives to such insect repellents. 63 Tips for using insect repellents Centre for Health Protection Hong Kong 2018 C Others: A compilation of available information on the usage of insect repellents and relevant precautions.
• Makes specific remarks on DEET-containing repellent precautions when applied on children, such as the use of roll-on instead of spray repellents. • Remarks that infants under the age of 6 should not use DEET-containing repellents. • Indicates importance of following the product label for guidelines and precautions, regardless of the repellent chosen. 64 The underlying reasons for very high levels of bed net use, and higher malaria infection prevalence among bed net users than non-users in the Tanzanian city of Dar es Salaam: A qualitative study Malar J 2017 D Level 4: A cross-sectional, qualitative study on the underlying reasons behind high levels of bed net use as well as higher malaria infection prevalence among bed net users than non-users.
• Provides potential explanations for compromised bet net efficacy and thus higher malaria infection prevalence among bed net users than non-users in other studies, bed net sharing, incomplete bed tucking, the touching of the net while sleeping, and the presence of holes in bed nets. • Indicates collateral benefits of bed net use mentioned by bed net users including the prevention of dust from landing on bed sheets and coverings as well as prevention of household pests. 65 The efficacy of long-lasting nets with declining physical integrity may be compromised in areas with high levels of pyrethroid resistance Malar J 2013 D Level 4: A cross-sectional survey on the impact of declining physical integrity in long-lasting insecticide-treated nets on efficacy.
• Indicates that long-lasting insecticide-treated nets with modest hole areas would permit the entrance and feeding of mosquitoes, compromising efficacy. • Suggests that long-lasting insecticide-treated nets are prone to the development of large holes within three years of use, compromising efficacy.
The effectiveness of older insecticide-treated bed nets (ITNs) to prevent malaria infection in an area of moderate pyrethroid resistance Malar J 2020 D Level 2b: A cohort study evaluating the effectiveness of older insecticide-treated bed nets on preventing malaria infection in moderate pyrethroid resistance areas.
• Indicates no statistically significant findings on the different in infection incidence between users and non-users of the bed nets. • Demonstrates that among insecticide-treated bed net uses, malaria incidence was significantly lower in users of bed nets with no holes compared to those who had bed nets with one hole or more. 67 Insecticide • Indicates derivation of immunisation from either passive or active means. • Classifies vaccination as a form of active immunisation which exposes unimmunised individuals to a pathogenic agent. • Indicates that vaccines stimulate the immune system to achieve long-term immunity through strong cellular and antibody responses.
• Concludes that effective immunisation must induce long-term stimulations of both arms of the adaptive immune system. • States that untreated bed nets are estimated to provide half the protective effect of insecticide-treated bed nets, and serves as merely a physical barrier.
• Indicates that insecticide-treated bed nets provide an additional chemical barrier to repel disease vectors. 78 Airflow attenuation and bed net utilization: Observations from Africa and Asia Malar J 2012 D Level 5: An observational study to assess the effect of bed nets on temperature, humidity and airflow in rural homes in Asia and Africa, thus further evaluate the associated thermal discomfort of users.
• Suggests that bed nets reduce airflow compared to unattenuated airflow, and may limit bed net use.
• Suggests that thermal discomfort associated with bed nets is most problematic during hot and humid climates, which is coincidentally the peak of malaria vector densities and pathogen transmission force.
• Indicates no statistically significant different in temperature or humidity between the inside and outside of the bed net.
• Suggests that higher bed net mesh size is correlated with decreased air flow.
• Encourages better designs to overcome such limitations. 79 Reported reasons for not using a mosquito net when one is available: A review of the published literature Malar J 2011 D Level 5: A literature review on the barriers to mosquito net use in malaria-pandemic countries through looking into published research on self-reported reasons.
• Indicates that thermal discomfort due to heat and perceived low mosquito density (complacency) are the two major identified reasons for non-use. • Mentions technical factors related to mosquito net use (unable or inconvenient to wash or hang mosquito net) as a reason for non-use. 80 Assessing the effective use of mosquito nets in the prevention of malaria in some parts of Mezam division, Northwest Region Cameroon Malar J 2016 D Level 4: A laboratory study and crosssectional questionnaire to assess the acceptability and efficacy of long-lasting insecticide-treated bed nets on malaria prevalence.
• Indicates statistically significant malaria prevalence reduction among users of longlasting insecticide-treated bed nets compared to non-users. • Shows that half of the respondents considered heat and the feeling of suffocation as the major problem with long-lasting insecticide-treated bed net use. • Suggests that vaccine underutilisation in the studied community was significantly associated with factors such as parental religious beliefs against vaccination, perceived risk of vaccine preventable diseases as low, and having more than 6 siblings. • Mentions the launch of the pilot RTS,S vaccination program as a potential prophylactic strategy against malaria. • Indicates that the phase 3 clinical trial of RTS,S was large-scale and demonstrated that four in ten cases of malaria can be prevented. • Mentions the integration of the RTS,S vaccine into the national immunisation programs of Malawi, Ghana and Kenya over the next 5 years, in hope of decreasing malaria mortalities. • Mentions that accessibility to all four doses of the vaccine for maximum protection is a challenge to the feasibility of the intervention. • Suggests importance of top-down coordination from government bodies down to community level.
• Emphasises that RTS,S only offers partial protection and is thus only a supplementary primary prevention strategy. 84 Barriers to effective uptake and provision of immunization in a rural district in Uganda PLoS One 2019 E Level 4: A cross-sectional mixed methods study to evaluate immunisation services and identify the gaps in health systems that contribute as barriers to effective uptake and provision of immunisation in Uganda.
• Indicates limited access to immunisation centres due to poor road terrain, in turn affecting program effectiveness and the timely delivery of supplies such as refrigerator gas and vaccines. • Suggests need for improvement in immunisation services in areas including vaccine supply, service delivery point expansion, more health workers, and better transport and tailored mechanisms. 85 The efficacy of some commercially available insect repellents for Aedes aegypti (Diptera: Culicidae) and Aedes albopictus (Diptera: Culicidae) J Insect Sci 2015 C Level 4: An interventional study to evaluate and compare the efficacies of some commercially-available insect repellents.
• Indicates that regarding the two mosquito species tested, Ae. Albopictus were generally less attracted to the subject's hand compared to Ae. Aegypti. • Suggests that different active ingredients in commercially available mosquito repellent products vary in terms of their duration and strength of repellence. • Indicates that citronella, a plant-based repellent, did not have any significant repellence effect. • Concludes that DEET-containing products have more long-lasting repellent effects. 86 The insect repellent N,Ndiethyl-m-Toluamide (DEET) induces angiogenesis via allosteric modulation of the M3 muscarinic receptor in endothelial cells Sci Rep 2016 C Level 5: A laboratory study to investigate the potential of angiogenesis induction of DEET and associated health risks.
• Demonstrates that DEET stimulates endothelial cells and promotes angiogenesis, in turn increasing tumour growth. • Encourages risk of assessment of DEET in humans to provide safe conditions of use.

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Is DEET a dangerous neurotoxicant?
Pest Manag Sci 2019 C Level 5: A review on the safety of DEET when used as an insect repellent.
• Indicates that while some studies reflect that DEET poses minor health risks from human use, a large analyses from the US Poison Centre has concluded that DEET presents little to no risk when applied according to product labels. • Suggests that the number of reports that document serious health effects after proper use of DEET is minimal. • Demonstrates that insecticide-treated net use in nearby compounds had a protective effect for child mortality, moderate anaemia, highdensity parasitaemia, and haemoglobin levels in compounds lacking the bed nets.
• Suggests that the community effect of widespread bed net coverage on nearby compounds without nets is potentially equivalent to that observed in villages with insecticide-treated bed net use.
• Reinforces importance of high coverage with insecticide-treated bed nets to maximise public health impact. 92 Preventing childhood malaria in Africa by protecting adults from mosquitoes with insecticide-treated nets PLoS Med 2007 D Level 5: A model-based study to assess and estimate insecticide-treated net coverage thresholds for entire populations to provide equivalent individual-and community-level protection from disease vectors.
• Indicates that high (80% use) of insecticidetreated nets to exclusive target young children and pregnant women delivers limited protection for these vulnerable groups. • Indicates that relatively modest coverage of all adults and children can achieve more equitable community-wide benefits equivalent to or greater than personal protection. 93 The ability of Anopheles gambiae mosquitoes to bite through a permethrin-treated net and the consequences for their fitness Sci Rep 2019 D Level 5: An entomological research to assess the ability of an insecticide-sensitive strain of Anopheles gambias to bite through a permethrin-treated or untreated net and their subsequent survival and fertility.
• Indicates that a majority of mosquitoes took blood through the insecticide-treated net despite permethrin irritancy. • Suggests that insecticide treatment reduced the biting time, blood-meal size and fertility of the mosquitoes, killing 15% of the mosquitoes within 24 hours of feeding, compared to no treatment of the bed nets. • Mentions that irritancy and toxicity of insecticide-treated nets to mosquitoes may potentially be reduced when mosquitoes contact and feed on bed net users. 94 Vaccines and vaccination against yellow fever -WHO Position Paper WHO 2013 E Others: A WHO position paper on vaccination against yellow fever.
• Mentions that while no human efficacy studies have been performed with the yellow fever vaccine, observations such as the absence of laboratory-associated infections in vaccinated workers and the occurrence of yellow fever only in unvaccinated people in Brazil and other South American countries following initial use support the protective effect of the vaccine. • Indicates that a single dose of yellow fever vaccine would suffice for a sustained life-long protective immunity against yellow fever disease. 95 Review article: Efficacy and duration of immunity after yellow fever vaccination: Systematic review on the need for a booster every 10 years Am J Trop Med Hyg 2013 E Level 2a: A systematic review on the protective efficacy and duration of immunity of yellow fever vaccine in residents living in and travelers to diseaseendemic areas, in turn assessment of the • Concludes that a single dose of yellow fever vaccine is highly efficacious and immunogenic, providing sustained life-long protective immunity against yellow fever.
need for a booster for the yellow fever vaccine.
• Suggests that a booster dose of yellow fever vaccine is not necessary. 96 Vaccines against tick-borne encephalitis: WHO position paper WHO 2011 E Others: A WHO position paper on vaccination against tick-borne encephalitis.
• Mentions that immunisation provides the most effective protection against tick-borne encephalitis.

• Mentions that all 4 vaccines manufactured by
Austria (1) • Mentions the launch of the pilot RTS,S vaccination program that requires four doses as a potential prophylactic strategy against malaria. • Indicates that the phase 3 clinical trial of RTS,S was large-scale and demonstrated that four in ten cases of malaria can be prevented. • Mentions the launch of the malaria vaccine pilot in Malawi, followed by Ghana and Kenya over the next 5 years, in hope of decreasing malaria mortalities. 101 Long-term use of antimalarial drugs in rheumatic diseases Clin Exp Rheumatol 2012 E Level 4: A case series to assess the longterm use of antimalarial drugs and potential causes of discontinuation.
• Suggests potential health risks and adverse events of antimalarials that prompt discontinuation, such as gastrointestinal, neuro-psychiatric and skin problems, as well as ophthalmologic adverse events like antimalarial retinopathy and rare irreversible loss of vision. • Suggests that antimalarials have a good balance between benefit and risk. • Emphasises on importance of ophthalmologic monitoring to look into the potential for rare but severe ophthalmologic toxicities when taking antimalarials. 102 Prophylaxis of Malaria Mediterr J Hematol Infect Dis 2012 E Level 5: A review on the nature, types, and potential barriers or problems that may arise from malaria chemoprophylaxis.
• Indicates that potential challenges to malaria chemoprophylaxis include barriers such as high costs, adverse reactions to medications and fatalities. • Recommends a revised guideline for chemoprophylaxis use by travellers in low risk areas. 103 Prevention of malaria in longterm travellers J Am Med Assoc 2006 E Level 3a: A systematic review on the risk of malaria in long-term travellers, recent developments in personal protective measures, safety and tolerability of malaria chemoprophylaxis during long-term use, and evaluation of relevant prevention strategies.
• Suggests that long-term travellers are at a higher risk of malaria infection than shortterm travellers. • Indicates that personal protective measures and chemoprophylaxis are not adequately used in long-term travellers. • Proposes strategies such as the discontinuation of chemoprophylaxis after the initial period and sequential regimens with different medications for chemoprophylaxis. • Points out that vivax malaria relapses cannot be prevented with current first-line chemoprophylaxis regimens. • Recommends individualised guidelines for malaria prevention in long-term travellers. 104 First FDA-approved vaccine for the prevention of dengue disease in endemic regions The U.S. Food and Drug Administration 2019 E Others: A news release on the first FDAapproved vaccine for dengue prevention in endemic regions.
• Mentions that Dengvaxia, the dengue vaccine, is believed to be 76% effective in targeting all dengue virus serotypes in people ages 9-16 who have laboratory-confirmed previous dengue infection and live in endemic areas. • Mentions that the second infection with dengue is often much more severe than the first, with the potential of developing dengue haemorrhagic fever (DHF • Highlights that families affected by the floods are exposed to greater risks of morbidity and mortality as a result of water-borne disease and VBD risks. • Mentions that VBDs are associated with solid waste accumulation. • Suggests that vectors such as the Aedes species frequently breed in areas such as garbage dumps. • Indicates that the management of solid waste is crucial in order to prevent development of environments which are favourable to vectors such as the Aedes species. 135 Household wastes as larval habitats of dengue vectors: Comparison between urban and rural areas of Kolkata, India PLoS One 2015 G Level 5: An entomological study to investigate the relationship between household wastes such as porcelain and plastic wastes and larval habitats of dengue vectors.
• Indicates that porcelain and plastic wastes are correlated with a higher larval productivity. • Suggests that household waste linkage to the productivity of Aedes is a risk factor for dengue epidemics. 136 Chemical signalling and insect attraction is a conserved trait in yeasts Ecol Evol 2018 J Level 2b: A cohort study on the attraction of insects towards different yeasts.
• Concludes that the flies studied have attraction towards all nine yeasts, which corroborates past research on the mutual interactions occurring between insects and yeasts.