Environmental Reservoirs of Vibrio cholerae: Challenges and Opportunities for Ocean-Color Remote Sensing

Abstract

The World Health Organization has estimated the burden of the on-going pandemic of cholera at 1.3 to 4 million cases per year worldwide in 2016, and a doubling of case-fatality-rate to 1.8% in 2016 from 0.8% in 2015. The disease cholera is caused by the bacterium Vibrio cholerae that can be found in environmental reservoirs, living either in free planktonic form or in association with host organisms, non-living particulate matter or in the sediment, and participating in various biogeochemical cycles. An increasing number of epidemiological studies are using land- and water-based remote-sensing observations for monitoring, surveillance, or risk mapping of Vibrio pathogens and cholera outbreaks. Although the Vibrio pathogens cannot be sensed directly by satellite sensors, remotely-sensed data can be used to infer their presence. Here, we review the use of ocean-color remote-sensing data, in conjunction with information on the ecology of the pathogen, to map its distribution and forecast risk of disease occurrence. Finally, we assess how satellite-based information on cholera may help support the Sustainable Development Goals and targets on Health (Goal 3), Water Quality (Goal 6), Climate (Goal 13), and Life Below Water (Goal 14).

Cholera Risk: A Machine Learning Approach Applied to Essential Climate Variables

“…Chlorophyll-a concentration is the key variable to estimate primary production in the marine environment [ 69 ], and cholera outbreaks have previously been found to occur following plankton blooms [ 25 ]. Phytoplankton blooms can stimulate bacterial growth by providing a food source, altering the pH of the water, offering host protection and supporting the growth of zooplankton and other marine hosts and reservoirs of V. cholerae [ 1 , 2 , 3 , 4 , 16 , 24 , 28 , 70 ]. Lagged effects are to be expected as the breakdown of phytoplankton increases nutrient availability for V. cholerae to flourish [ 16 , 71 ], and is in agreement with previous studies showing the influence of plankton on cholera to be present up to a lag of eight weeks [ 72 ].…”

“…The bacteria Vibrio cholerae are a native constituent of aquatic environments [ 1 ], existing generally in brackish, coastal and oceanic waters as free floating bacterioplankton or attached to non-living particles and living hosts [ 2 , 3 , 4 ]. These bacteria are heterotrophic and play key roles in aquatic ecosystems, through host-pathogen and predatory-prey interactions, as well as in biogeochemical cycling [ 5 , 6 ].…”

“…To our knowledge, relationships with cholera outbreaks have so far been demonstrated with seven essential climate variables [ 22 ], including sea surface temperature [ 16 , 23 , 24 , 25 , 26 , 27 ]; salinity and saltwater intrusions [ 16 , 25 , 27 , 28 , 29 ]; plankton and chlorophyll-a concentration [ 1 , 4 , 16 , 30 ]; sea level/height [ 24 , 26 , 31 ]; precipitation [ 5 , 26 , 32 ]; land surface temperatures [ 15 , 32 , 33 ]; and soil moisture [ 16 ]. A number of these studies used field or laboratory experiments with V. cholerae while others have taken an epidemiological approach to explore relationships with actual cholera incidence or outbreaks.…”

Dynamics of Vibrio cholerae in a Typical Tropical Lake and Estuarine System: Potential of Remote Sensing for Risk Mapping

“…Cholera is a water-associated disease with up to four million cases and 143,000 deaths reported worldwide every year [1]. Ecosystem-based strategies, which involve identifying reservoirs and elucidating movements of disease-causing organisms, have been found to be successful for managing public health issues related to cholera [2,3]. More than 200 sero-groups of Vibrio cholerae are known, of which O1 and O139 are associated with seven cholera pandemics [4].…”

Ecoepidemiology and Potential Transmission of Vibrio cholerae among Different Environmental Niches: An Upcoming Threat in Egypt

“…Cholera is an upsetting water- and food-borne epidemic and a pandemic life-threatening diarrheal disease caused by Vibrio cholerae that affects different hosts and species [ 1 , 2 ]. The gram-negative bacterium V. cholerae is a facultative pathogen that has both human and environmental stages in its life cycle [ 3 ].…”