Recurrent Cholera Outbreaks in Sub-Saharan Africa: Moving beyond Epidemiology to Understand the Environmental Reservoirs and Drivers

Abstract

Recurrent cholera outbreaks in sub-Saharan Africa (SSA) attracted a lot of research interest, raising questions about the effectiveness of current prevention and control methods. However, research on cholera and other water-borne diseases in Africa is dominated by epidemiological studies, while investigations on the environmental drivers and reservoirs of cholera remain scarce. The current discourse relating cholera to the environment in SSA is often limited to the rudimentary statement that, “cholera is caused by the consumption of contaminated water and food”. Yet, beyond this simplistic view, literature elsewhere shows that cholera outbreaks are controlled by its complex interactions with environmental drivers and reservoirs. This brings to question whether cholera can be eradicated in SSA without understanding these complex interactions. The current review seeks to (1) highlight the nature and dynamics of recent cholera outbreaks in SSA, (2) discuss the importance of environmental reservoirs of Vibrio cholerae, and anthropogenic and hydroclimatic drivers in controlling the dynamics of cholera outbreaks, and (3) highlight key knowledge gaps and future research directions, and the need to harness emerging research tools such as modeling, machine learning, data mining, and genomics techniques to better understand the cholera dynamics. By bringing to fore these often-overlooked issues in cholera research, we seek to stimulate discussion, and promote a shift toward cross-disciplinary research on cholera and other water-borne diseases in SSA and beyond.

Leaving no stone unturned in light of the COVID-19 faecal-oral hypothesis? A water, sanitation and hygiene (WASH) perspective targeting low-income countries

“…Communities with potential high risks of COVID-19 transmission include: (1) densely populated informal settlements such as squatter camps, slums and refugee camps without access to centralised drinking water systems ( Corburn et al, 2020 ; WHO, 2020a , WHO, 2020b , WHO, 2020c ), and (2) urban and peri-urban areas without reliable sources of drinking water, forcing communities to depend on unsafe surface and groundwater sources ( Oswald et al, 2007 ). Evidence exists linking drinking water contamination via wastewater and on-site sanitation to outbreaks of human infections such as cholera and typhoid in developing countries, including those in Africa ( Ahmed et al, 2011 ; Gwenzi and Sanganyado, 2019 ). However, data relating to SARS-CoV-2 are scarce, and it is currently unclear whether or not indicator and pathogenic microorganisms often detected in contaminated aquatic systems are intermediate hosts of SARS-CoV-2.…”

The ‘thanato-resistome’ - The funeral industry as a potential reservoir of antibiotic resistance: Early insights and perspectives

“…In other words, the subject falls in ‘no man's land’, thereby creating a research vacuum. This scenario has been pointed out in the case of water-borne diseases, where research on environmental drivers and reservoirs of cholera received a cursory attention relative to epidemiology ( Gwenzi and Sanganyado, 2019 ).…”

“…This notion is also reflected in the education system, where aspects related to industrial production systems (e.g., heat stress, fatigue, working at heights) tend to dominate the occupational safety, health and environment curricula relative to those pertinent to the funeral industries (e.g., infectious materials). Evidence shows that when a research subject falls between two disparate disciplines, it tends to be neglected by both disciplines ( Gwenzi and Sanganyado, 2019 ). In other words, the subject falls in ‘no man's land’, thereby creating a research vacuum.…”

An Overview of Cholera Epidemiology: A Focus on Africa; with a Keen Interest on Nigeria

“…The bacterium V. cholerae, definitely has reservoirs in the environment, which harbour it until it gets to be released into the definitive host (humans), to cause disease outbreaks. Since its proliferation is fostered by salty environments like estuarine and marine waters, there is, therefore, a close relationship between V. cholerae and marine organisms, especially seafood like crabs, crayfish, bivalves (shellfishes) [19]. However, in the Indian continent, Zanzibar and Malawi in Africa, egg masses of the "non-biting midges" (Diptera Chironomidae), have been reported to serve as reservoirs of V. cholerae [20].…”

“…The political unrest marked by civil war and a humanitarian crisis has left Yemen in a state of cholera rampage since 2016 [19]. The first outbreaks which started in September 2016, and the second in April 2017, have registered above 1000,000 suspected cases.…”