In a recent study posted to the medRxiv* preprint server, researchers assessed whether the 2030 goals of the Global Task Force for cholera control are attainable.
Study: Cholera past and future in Nigeria: are the Global Task Force on Cholera Control’s 2030 targets achievable? Image Credit: Kateryna Kon/Shutterstock
This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources
Background
The Global Task Force on Cholera Control (GTFCC) was founded in 1992 as a global cooperation of over 50 institutions. In 2017, the GTFCC issued "Ending Cholera: A Global Roadmap to 2030."
The Roadmap urged partner groups to join the Declaration to End Cholera, which centered on three axes: (1) rapid identification and action, (2) interventions in hotspots for Cholera, and (3) coordination on all levels.
The GTFCC intends to end uncontrolled cholera outbreaks on a national scale by 2030 and eradicate the disease from 20 nations, leading to a 90% reduction in cholera-related mortality. Given the current rate of development and progress, it is uncertain whether these aims will be attained by 2030.
About the study
In the present study, researchers evaluated the feasibility of achieving the GTFCC objectives in Nigeria and highlighted areas wherein the three axes should be reinforced to achieve and exceed these objectives.
Due to the GTFCC's emphasis on lowering mortality, the number of recorded cholera deaths was incorporated into the historical analysis. To make the data more comparable, the cholera deaths were converted from raw numbers to a mortality rate. The World Health Organization (WHO) 's Global Health Observatory (1970-2016) as well as the Global Health Data Exchange (GHDx) (1990-2016), were consulted for cholera mortality statistics.
The forecasted temperature and precipitation information was obtained from WorldClim at administrative level 1 with a monthly temporal resolution. WorldClim data include scaled-down prospective gridded temperature and precipitation estimates from Coupled Model Intercomparison Project 6 (CMIP6), compiled for nine global climate models. The team employed a time series of historic cholera mortalities per 100,000, along with social and environmental factors, to depict the evolution of Cholera and its related risk factors over time.
National annual cholera information was extracted from the WHO Global Health Observatory and translated into a binary outcome variable representing the occurrence of cholera outbreaks. Through a process of covariate selection, 19 environmental and social factors were examined. Multivariate generalized linear models were then fit to the data. Employing the two models, five prediction scenarios for Cholera in the year 2070 were developed:
- Scenario 1 (S1) - The best-case scenario that satisfies the SDG and RCP4.5
- Scenario 2 (S2) - Intermediate advancement scenario from S1 to S3
- Scenario 3 (S3) - Limited development and carbon reductions, but advancement toward SDGs and IPCC targets.
- Scenario 4 (S4) - Some reversal from present standards of sustainable development and higher emissions
- Scenario 5 (S5) - Worst-case situation with a dramatic reversal in development and rising emissions.
Results
The time series demonstrated the historically high cholera burden observed in Nigeria, as was evident from the GHDx data. The GHDx data showed a sharp reduction from 16.0 cases/100,000 reported in 1991 to 1.8 cases/100,000 noted in 2017, with a few plateauing intervals. Comparatively, according to WHO data, Cholera arises rather steadily over time, with high peaks of 5.1 cases per 100,000 in 1971, 7.8 cases per 100,000 in 1991, and 1.7 cases per 100,000 in 1999. In addition, it is important to highlight that the GHDx results indicate a significantly higher death rate per 100,000 individuals.
The autocorrelation function (ACF) for the two datasets demonstrated a steady decline in the confidence interval bands. The ACF decay indicated that the impact of time is not especially important in either of the cholera sets. The limited influence of time was also highlighted by the ARIMA analysis as it revealed a flat projection, forecasting cholera fatalities at the current rate.
Between S1 to S3, the incidence of Cholera in Nigeria declined from 0.95 in all five scenarios to 0.83 in the first and 0.92 in the second scenario by 2070. These changes were comparatively small, and multiple confidence ranges overlapped. The reductions to 2070 were negligible, particularly when the study considered the levels of progress in the S1 scenario. In S4 and S5, wherein environmental and socioeconomic conditions deteriorated, cholera outbreaks increased from 0.95 to 0.98 in S4 and 0.99 in S5.
Several regional heterogeneities were observed in the cholera R subnational predictions, which may assist in understanding a portion of the national projections' uncertainty. The number of states with R values greater than 1 declined from S1 to S3. Furthermore, for S4 and S5, the changes appeared to be more complex, as some states fared better than others in the face of deteriorating socioeconomic and environmental situations.
Conclusion
Overall, the study findings showed that within certain regions of Nigeria, the 2030 goals may be attained by 2030, but on a national scale, more effort is required, especially in terms of access to and incentives for cholera testing, poverty reduction, sanitation expansion, and urban planning. The results demonstrated the significance of modeling studies, how they might be used to improve cholera policy, and the possibility for such an approach to be employed in other contexts.
This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources
Article Revisions
- May 17 2023 - The preprint preliminary research paper that this article was based upon was accepted for publication in a peer-reviewed Scientific Journal. This article was edited accordingly to include a link to the final peer-reviewed paper, now shown in the sources section.
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