Malaria, mangroves, and migration: challenges for small island developing states in the Caribbean

Besides climate change and unsustainable exploitation of the environment, socioeconomic inequality and political unrest may also contribute to infectious disease outbreaks in the Caribbean archipelago. Migration among rural coastal communities can reduce the effectiveness of disease monitoring and hinder the isolation of people in infected communities—both strategies underpinning integrated control of emerging infectious disease (EID). 

Caribbean islands experience high rates of unregulated immigration from several South American counties.1 The worsening economic and political situation in Venezuela in 2018 coincided with a sudden marked rise in malaria, with a reported 51% prevalence.2 This, in combination with civil unrest, may result in more frequent outbreaks of malaria outbreaks in the Caribbean in the future. 

Since the early 2000s the Caribbean has been considered completely malaria-free. Caribbean small island developing states have maintained this status through an integrated control approach, including continued and intensive monitoring, isolation of individuals within infected communities, and the control of mosquito breeding sites by draining stagnant water bodies, community fumigation and other environmental management schemes.3,4

Anopheles is the mosquito vector of Plasmodium; understanding this vector underpins effective malaria control strategies. This mosquito tolerates brackish water habitats, and recent global environmental changes and unsustainable exploitation of the environment have increased the size of this habitat. For example, approximately 10% of Trinidad’s coastline is fringed by mangrove ecosystems,5 which buffer inland saltwater intrusion. However, the loss of coastal mangrove caused by increased sea level and coastal erosion, coupled with coastal infrastructural development, has resulted in saltwater intrusion of watersheds, and inland colonization by mangroves. This habitat provides fertile new breeding grounds for vectors such as brackish water-tolerant mosquitoes. In addition, the increased frequency of tropical storms across the Atlantic and flooding provides more stagnant water habitats for mosquito reproduction.6 These changes undermine the treatment of stagnant water habitats that a successful approach to controlling emerging infectious disease relies on.

Control of EIDs such as arboviruses and malaria require increased resources from governments, particularly focused on disease monitoring in rural, coastal communities. However, more needs to be done. The United Nations has declared 2021 to 2031 as the Decade of Ocean Science for Sustainable Development.7 The aim is to reverse declining oceanic health caused by climate change, but control of EIDs is equally crucial, and this initiative has potentially much wider implications, as the One Health approach suggests.8 Marine spatial planning, a strategy for capitalizing on the blue economy, directly addresses habitat use and loss.9 Particularly in the Caribbean, this strategy should focus on halting the erosion of coastal mangroves.

Like the rest of the world, the small island developing states of the Caribbean face a multitude of challenges related to mass movement of human populations, elevated ambient air temperatures, changes in weather and rainfall patterns, coastal erosion, human-induced habitat change, and the spread of infectious disease vectors. These changes put additional pressures on the control of EIDs, and the consequence is that Caribbean states may soon no longer be considered as completely malaria-free. Indeed, the status of EIDs is in constant need of re-evaluation, demanding increased investment with the vision that our health and wellbeing depend on the health and wellbeing of our environment. For example, the Mayaro arborvirus, which has its origins in South and Central America, is predicted to become a major epidemic in the future, following in the steps of the recent pandemics caused by Chikungunya and Zika viruses.10 The vector Haeamogus sp mosquito was typically found in tropical inland forest but now as coastal temperatures are rise consistently, the vector is also found within mangrove ecosystems as well.10

In line with the One Health approach,11 we need to make significant investments to redress ecological and environmental imbalance resulting from human activities. We need to better anticipate how changes in habitat caused by human activities and climate change can result in range shifts of parasites and their vectors, which enables us to implement control measures before outbreaks take place. In keeping with the UN’s Sustainable Development Goals, we must critically assess and mitigate the novel risks for EID outbreaks associated with the environmental changes resulting from these activities. This is critical for the effective control of EIDs, and health and wellbeing in the Caribbean and elsewhere in the world.

Ryan S. Mohammed, The University of the West Indies, & Environmental Research Institute Charlotteville (ERIC), Tobago

Cock van Oosterhout, University of East Anglia, UK

Competing interests: None declared.

This article is part of a series commissioned by The BMJ for the World Innovation Summit for Health (WISH) 2020. The BMJ peer reviewed, edited, and made the decisions to publish. The series, including open access fees, is funded by WISH. 


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