A Review of the Environmental Trigger and Transmission Components for Prediction of Cholera

Abstract

Climate variables influence the occurrence, growth, and distribution of Vibrio cholerae in the aquatic environment. Together with socio-economic factors, these variables affect the incidence and intensity of cholera outbreaks. The current pandemic of cholera began in the 1960s, and millions of cholera cases are reported each year globally. Hence, cholera remains a significant health challenge, notably where human vulnerability intersects with changes in hydrological and environmental processes. Cholera outbreaks may be epidemic or endemic, the mode of which is governed by trigger and transmission components that control the outbreak and spread of the disease, respectively. Traditional cholera risk assessment models, namely compartmental susceptible-exposed-infected-recovered (SEIR) type models, have been used to determine the predictive spread of cholera through the fecal–oral route in human populations. However, these models often fail to capture modes of infection via indirect routes, such as pathogen movement in the environment and heterogeneities relevant to disease transmission. Conversely, other models that rely solely on variability of selected environmental factors (i.e., examine only triggers) have accomplished real-time outbreak prediction but fail to capture the transmission of cholera within impacted populations. Since the mode of cholera outbreaks can transition from epidemic to endemic, a comprehensive transmission model is needed to achieve timely and reliable prediction with respect to quantitative environmental risk. Here, we discuss progression of the trigger module associated with both epidemic and endemic cholera, in the context of the autochthonous aquatic nature of the causative agent of cholera, V. cholerae, as well as disease prediction.

Combating cholera by building predictive capabilities for pathogenic Vibrio cholerae in Yemen

“…Table 2 summarizes the BHC criteria used to evaluate the CRM trigger module, which provides an assessment of cholera risk at least four weeks in advance (based on previously published results 32 ). The motivation for using risk score, rather than prevalence or incidence, is the ability to circumvent missing data during public health emergencies, a situation common during most major cholera outbreaks.…”

“…Disease prediction can be achieved by recognizing that disease progression comprises two components, trigger and transmission, which result in an outbreak and, subsequently, public health emergency 23 , 32 . For cholera, "trigger" represents those mechanisms that stimulate the growth, multiplication, and distribution of V. cholerae bacteria in the environment.…”

Predictive Intelligence for Cholera in Ukraine?

“…The cholera epidemic mode can become endemic if safe drinking water access is not ensured. A cholera outbreak requires distinct trigger and transmission mechanisms (A. S. Jutla et al., 2010; Usmani et al., 2021). The trigger is defined as conditions that start (or initiate) an outbreak with environmental dynamics and a few cases in humans, and the transmission mechanism involves spreading the infection into human communities.…”

“…Cholera outbreaks generally occur in two modes (Codeço, 2001;Khan et al, 2017Khan et al, , 2018Usmani et al, 2021): epidemic, namely a sudden occurrence of cholera in a region where a considerable disturbance occurs that causes interference with access to drinking water and proper sanitation and the human population is not prepared to deal with the disease; and endemic, a continuous occurrence of sporadic cholera cases with quasi-predictable seasonality. The cholera epidemic mode can become endemic if safe drinking water access is not ensured.…”

Major Stressors Favoring Cholera Trigger and Dissemination in Guinea-Bissau (West Africa)

“…Therefore, human exposure to potential pathogenic Vibrio species can be mitigated but not eliminated. Although high-population areas with poor access to safe drinking water and without sanitation contribute to the emergence and spread of cholera, unequivocal evidence that environmental factors have a concomitant major influence on the disease dynamics is now established [ 7 , 8 , 9 , 10 ]. This influence on disease dynamics can either be direct or realized through the control of other organisms that serve as reservoirs for the bacterium, such as copepods [ 9 , 11 , 12 ].…”