Mosquito Net Use in an Artisanal East African Fishery

Assessing the impact of insecticide-treated nets in the face of insecticide resistance on malaria control

The mosquito-borne disease, malaria, continues to impose a devastating health and economic burden worldwide. In malaria-endemic areas, insecticide-treated nets (ITNs) have been useful in curtailing the burden of the disease. However, mosquito resistance to insecticides, decay in ITN efficacy, net attrition, etc., undermine the effectiveness of ITNs in combatting malaria. In this study, mathematical models that account for asymptomatic infectious humans (through a partially immune class or a separate asymptomatic infectious class), insecticide resistance, and decay in ITN efficacy are proposed and analyzed. Analytical and numerical results of the models when ITN efficacy is constant show that there are parameter regimes for which a backward bifurcation occurs. Local and global sensitivity analyses are performed to identify parameters (some of which are potential targets for disease control) with the most significant influence on the control reproduction (R_c) and disease prevalence. These influential parameters include the maximum biting rate of resistant mosquitoes, ITN coverage, initial ITN efficacy against sensitive mosquitoes, the probability that an infectious mosquito (human) infects a susceptible human (mosquito), and the rate at which adult mosquitoes develop (lose) resistance to insecticides. Simulations of the models show that accounting for asymptomatic infectious humans through a separate class, or not accounting for the decay in ITN efficacy leads to an underestimation of disease burden. In particular, if the initial efficacy of ITNs against sensitive and resistance mosquitoes is 96%, the minimum ITN coverage required to reduce R_c below one (and hence, contain malaria) is approximately 11% (27%) lower when ITN efficacy is averaged (constant) for a model with a separate asymptomatic class. For the model with a partially immune class and decaying ITN efficacy, reducing R_c below one is impossible even if the entire populace uses ITNs. The study shows that replacing ITNs before their prescribed lifespans, or designing ITNs with longer lifespans is important for malaria control. Furthermore, the study shows that piperonyl butoxide (PBO) ITNs (which inhibit or reverse insecticide resistance) outperform regular ITNs in malaria control. Hence, prospects for effectively controlling malaria are enhanced by widespread use of high quality ITNs (e.g. PBO ITNs), especially if the useful lifespans of the ITNs are long enough and the ITNs are replaced before the end of their useful lifespans.

An evolutionary game model of individual choices and bed net use: elucidating key aspect in malaria elimination strategies

Insecticide-treated net (ITN) is the most applicable and cost-effective malaria intervention measure in sub-Saharan Africa and elsewhere. Although ITNs have been widely distributed to malaria-endemic regions in the past, their success has been threatened by misuses (in fishing, agriculture etc.) and decay in ITN efficacy. Decision-making in using the ITNs depends on multiple coevolving factors: malaria prevalence, mosquito density, ITN availability and its efficacy, and other socio-economic determinants. While ITN misuse increases as the efficacy of ITNs declines, high efficacy also impedes proper use due to free-riding. This irrational usage leads to increased malaria prevalence, thereby worsening malaria control efforts. It also remains unclear if the optimum ITN use for malaria elimination can be achieved under such an adaptive social learning process. Here, we incorporate evolutionary game theory into a disease transmission model to demonstrate these behavioural interactions and their impact on malaria prevalence. We show that social optimum usage is a function of transmission potential, ITN efficacy and mosquito demography. Under specific parameter regimes, our model exhibits patterns of ITN usage similar to observed data from parts of Africa. Our study suggests that the provision of financial incentives as prompt feedback to improper ITN use can reduce misuse and contribute positively towards malaria elimination efforts in Africa and elsewhere.

Sub-Saharan Africa Freshwater Fisheries under Climate Change: A Review of Impacts, Adaptation, and Mitigation Measures

Sub-Saharan Africa’s freshwater fisheries contribute significantly to the livelihoods and food security of millions of people within the region. However, freshwater fisheries are experiencing multiple anthropogenic stressors such as overfishing, illegal fishing, pollution, and climate change. There is a substantial body of literature on the effects of climate change on freshwater fisheries in Sub-Saharan Africa. This study reviews the existing literature and highlights the effects of climate change on freshwater fisheries, the adaptation strategies of fishery-dependent households in response to the effects, and fisheries’ management and mitigation efforts in the face of climate change. The general effects of climate change on freshwater environments include warming water temperatures, increased stratification, modified hydrological processes, and increased pollutants. These effects adversely affect the physiological processes of fish and the overall wellbeing of fishery-dependent people. To cope with the effects of fluctuating fishery resources due to climate change, fishery-dependent people have adopted several adaptation strategies including livelihood diversification, changing their fishing gear, increasing their fishing efforts, and targeting new species. Several management attempts have been made to enhance the sustainability of fishery resources, from local to regional levels. This study recommends the participation of the resource users in the formulation of policies aimed at promoting climate change adaptation and the resilience of freshwater fisheries for sustainable development.

Implications of Insecticide-Treated Mosquito Net Fishing in Lower Income Countries

INTRODUCTION

Insecticide-treated mosquito nets (ITNs) are highly effective for the control of malaria. Yet widely distributed ITNs have been repurposed as fishing nets throughout the world.

OBJECTIVES

Herein we present a synthesis of the current knowledge of ITN fishing and the toxicity of pyrethroids and discuss the potential implications of widespread fishing with ITNs. We further review effective management strategies in tropical fisheries to explore a framework for managing potential ITN fishing impacts.

DISCUSSION

Pyrethroids are toxic to fish and aquatic environments, and fishing with ITNs may endanger the health of fisheries. Furthermore, although human toxicity to the pyrethroid insecticides that impregnate ITNs is traditionally thought to be low, recent scientific advances have shown that pyrethroid exposure is associated with a host of human health issues, including neurocognitive developmental disorders, diabetes, and cardiovascular disease. Although it is known that ITN fishing is widespread, the implications for both fisheries and human communities is understudied and may be severe. https://doi.org/10.1289/EHP7001.

"After those nets are torn, most people use them for other purposes": an examination of alternative bed net use in western Kenya

BACKGROUND

Alternative long-lasting insecticidal net (LLIN) use for purposes other than sleeping protection from mosquitoes is widely debated as a limitation to successful malaria control efforts, yet rarely rigorously studied.

METHODS

A cross-sectional survey of 1217 households in an epidemic highland site and an endemic lowland site in western Kenya collected information on alternative use in three ways: direct observations, participant self-report, and participant reporting of community-level practices. LLIN misuse was defined as use of an intact net for alternative purposes and repurposing as alternatively using an old or damaged net. Associations between households with observed repurposed nets and universal access and household net use were examined.

RESULTS

Households describe repurposing nets when they are torn and/or old. Repurposed nets were observed in 8.1% (52/643) highlands households and 33.0% (184/574) lowlands households. Repurposed nets served as chicken coops (33% highlands, 20% lowlands), fences (37% highlands, 25% lowlands), tree covers (22% lowlands), curtains (3% highlands), covering bathrooms (1.5% highlands, 9% lowlands), and washing sponges (13% lowlands). No association was found between repurposing and universal access or household net use. Misuse was rare. Of 379 repurposed nets, 4 (1.06%) were in good condition with no holes. Of 1,758 active nets, 13 (0.74%) were misused.

CONCLUSIONS

Alternative net use in this study involved repurposing rather than misuse. Repurposing was not detrimental to malaria prevention efforts in these communities. Standardized measurement of alternative net use should be used to better understand the practice and its potential impact on the success of malaria interventions.

The perverse fisheries consequences of mosquito net malaria prophylaxis in East Africa

Malaria is a serious global health issue, with around 200 million cases per year. As such, great effort has been put into the mass distribution of bed nets as a means of prophylaxis within Africa. Distributed mosquito nets are intended to be used for malaria protection, yet increasing evidence suggests that fishing is a primary use for these nets, providing fresh concerns for already stressed coastal ecosystems. While research documents the scale of mosquito net fisheries globally, no quantitative analysis of their landings exists. The effects of these fisheries on the wider ecosystem assemblages have not previously been examined. In this study, we present the first detailed analysis of the sustainability of these fisheries by examining the diversity, age class, trophic structure and magnitude of biomass removal. Dragnet landings, one of two gear types in which mosquito nets can be utilised, were recorded across ten sites in northern Mozambique where the use of Mosquito nets for fishing is common. Our results indicate a substantial removal of juveniles from coastal seagrass meadows, many of which are commercially important in the region or play important ecological roles. We conclude that the use of mosquito nets for fishing may contribute to food insecurity, greater poverty and the loss of ecosystem functioning.

Medical equipment donation in low-resource settings: a review of the literature and guidelines for surgery and anaesthesia in low-income and middle-income countries

Background

Medical equipment donation to low-resource settings is a frequently used strategy to address existing disparities, but there is a paucity of reported experience and evaluation. Challenges such as infrastructure gaps, lack of technological and maintenance capabilities, and non-prioritisation of essential supplies have previously been highlighted. This pragmatic review summarises existing guidelines and literature relevant to surgical and anaesthesia equipment, with recommendations for future initiatives and research.

Methods

Retrospective literature review including both academic and grey literature from 1980 to 2018. We conducted a narrative synthesis to identify key factors that were condensed thematically.

Results

Thirty-three biomedical equipment donation guidelines were identified from governments, WHO, World Bank, academic colleges and non-governmental organisations, and 36 relevant studies in peer-reviewed literature. These highlighted the need to consider all stages of the donation process, including planning, sourcing, transporting, training, maintaining and evaluating equipment donation. Donors were advised to consult national guidelines to ensure equipment was appropriate, desirable and non-costly to both parties. User training and access to biomechanical engineers were suggested as necessary for long-term sustainability. Finally, equitable partnerships between donors and recipients were integral to reducing inappropriate donations and to improve follow-up and evaluation.

Conclusion

There is a paucity of evidence on the causes of success or failure in medical equipment donation, despite its domination of equipment sourcing across many low-resource settings. Equitable partnerships, consultation of policies and guidelines, and careful planning may improve equipment usability and life span. A concerted effort is required to increase awareness of guidelines among health professionals worldwide.

The use of mosquito nets in fisheries: A global perspective

Free or subsidised mosquito net (MN) distribution has been an increasingly important tool in efforts to combat malaria in recent decades throughout the developing world, making great strides towards eradicating this hugely detrimental disease. However, there has been increasing concern in the natural resource management and healthcare communities over alternative use of MNs, particularly in artisanal fisheries where it has been suggested they pose a threat to sustainability of fish stocks. So far, little evidence has been presented as to the global prevalence and characteristics of MN fishing, limiting global management initiatives and incentives for action across disciplines. We conducted a rapid global assessment of mosquito net fishing (MNF) observations from expert witnesses living and/or working in malarial zones using an internet survey. MNF was found to be a broadly pan-tropical activity, particularly prevalent in sub-Saharan Africa. MNF is conducted using a variety of deployment methods and scales including seine nets, scoop/dip nets, set nets and traps. MNF was witnessed in a broad range of marine and freshwater habitats and was seen to exploit a wide range of taxa, with capture of juvenile fish reported in more than half of responses. Perceived drivers of MNF were closely related to poverty, revealing potentially complex and arguably detrimental livelihood and food security implications which we discuss in light of current literature and management paradigms. The key policies likely to influence future impacts of MNF are in health, regarding net distribution, and natural resource management regarding restrictions on use. We outline critical directions for research and highlight the need for a collaborative, interdisciplinary approach to development of both localised and broad-scale policy.