Association between air raids and reported incidence of cholera in Yemen, 2016-19: an ecological modelling study

BACKGROUND

Yemen continues to endure cholera outbreaks during ongoing conflict and destructive environmental events. Air raids have been used throughout the conflict to target military and civilian infrastructure. We aimed to assess the association between air raids and cholera incidence while taking into account geographical, environmental, economic, and demographic factors that drive outbreaks.

METHODS

In this ecological modelling study, we used data from Sept 12, 2016, to Dec 29, 2019, for the number of air raids, vegetation coverage, surface water, precipitation, temperature, economic variables, and cholera case and population data to model the association between conflict and the weekly incidence of cholera (per 100 000 people) in Yemen. Data were transformed into weekly intervals and governorates were categorised according to air raid severity (the number of raids in the previous 3 months). We used a negative binomial generalised additive model that accounted for geographical location and environmental, temporal, economic, and demographic variables to estimate incidence rate ratios for the association between air raid severity and cases of cholera.

FINDINGS

During the study period, 2 107 912 cases of cholera were reported in Yemen, and a minimum of 11 366 air raids were recorded. After controlling for relevant factors, compared with no air raids, all other levels of air raid severity were significantly associated with cholera incidence. The largest effect was noted in governorates with severe air raid levels (ie, ≥76 during the previous 3 months), which had an incidence rate ratio of 2·06 (95% CI 1·59-2·69; p<0·0001) for cholera compared with governorates with no air raids in the previous 3 months. Economic factors were also significantly associated with increased cholera incidence.

INTERPRETATION

Air raids were significantly associated with the burden of cholera in Yemen, even after controlling for other relevant factors. Quantification of this relationship further shows that the cholera outbreak is largely a result of human action rather than a natural occurrence, and demonstrates the conflict's devastating effects on health. Our findings highlight the need for ceasefire and peacebuilding efforts, as well as infrastructure and economic restoration, to reduce Yemen's cholera burden.

FUNDING

None.

TRANSLATION

For the Arabic translation of the abstract see Supplementary Materials section.

Communicable diseases in northwest Syria in the context of protracted armed conflict and earthquakes

The earthquakes in Türkiye and Syria in February, 2023, have caused further devastation in northwest Syria-an area already affected by protracted armed conflict, mass forced displacement, and inadequate health and humanitarian provision. The earthquake damaged infrastructure supporting water, sanitation, and hygiene, and health-care facilities. The disruptions to epidemiological surveillance and ongoing disease control measures resulting from the earthquake will accelerate and expand ongoing and new outbreaks of many communicable diseases including measles, cholera, tuberculosis, and leishmaniasis. Investing in existing early warning and response network activities in the area is essential. Antimicrobial resistance, which had already been an increasing concern in Syria before the earthquake, will also be exacerbated given the high number of traumatic injuries and breakdown of antimicrobial stewardship, and the collapse of infection prevention and control measures. Tackling communicable diseases in this setting requires multisectoral collaboration at the human-animal-environment nexus given the effect of the earthquakes on all these sectors. Without this collaboration, communicable disease outbreaks will further strain the already overburdened health system and cause further harm to the population.

Geographical Origin, WASH Access, and Clinical Descriptions for Patients Admitted to a Cholera Treatment Center in Northwest Syria between October and December 2022

Background  On September 10, 2022, a cholera outbreak was declared in Syria for the first time in over a decade of protracted conflict. As of May 20, 2023, 132,782 suspected cases had been reported, primarily in northwest and northeast Syria. We aim to provide a detailed description of water sources and clinical status of a patient cohort seen at a cholera treatment center (CTC) in northwest Syria. Methods  We retrospectively identified patients with confirmed cholera who presented to the CTC in Idlib governorate between October 8 and December 18, 2022. Data were obtained from clinical case records and analyzed in R v4.0.4. Results  Ninety-four patients (55.3% men) were treated at the CTC. Thirty-five patients were severely dehydrated (Plan C treatment), 54 had some dehydration (Plan B), and 5 had no dehydration (Plan A). Most patients were between 11 and 20 years old ( n  = 25, 26.6%) or 31 and 40 years old ( n  = 19, 20.2%). Note that 70.2% ( n  = 66) of patients were seen in November 2022 and most were from Harim district ( n  = 44, 46.8%). Public wells ( n  = 46, 48.9%) and water trucking ( n  = 41, 43.6%) were the most commonly used water sources. Note that 76.6% ( n  = 72) did not have access to chlorine-treated water. Forty-seven patients (50%) had more than five water, sanitation, and hygiene (WASH)-related cholera risk factors. Following treatment, six patients were transferred to another treatment center, three died (case fatality rate: 3.2%), and the remainder were discharged. Conclusion  Most patients reported WASH-related risk factors for cholera, reflecting the poor state of WASH in northwest Syria after over a decade of conflict. This relates to the direct and indirect impacts of urban and periurban violence as well as the underfunded humanitarian response. Strengthening WASH and health promotion are important components to control the outbreak.

Analyzing Health of Forcibly Displaced Communities through an Integrated Ecological Lens

Health care among forcibly displaced persons is frequently driven by siloed approaches. Aspects of the built environment, social factors, and the bidirectional relationship between the changing ecosystem and residents are often ignored in health policy design and implementation. While recognizing factors that create a preference for siloed approaches and appreciating the work of humanitarian agencies, we argue for a new data-driven and holistic approach to understand the health of the forcibly displaced. It should be rooted in the realities of the emergence of new diseases, dynamic demographics, and degrading environments around the displaced communities. Such an approach envisions refugee and internally displaced camps as dynamic, complex ecosystems that alter, and are altered by, spatial and temporal factors. At the root of this approach is the necessity to work across disciplines, to think holistically, to go beyond treating single ailments, and to develop ethical approaches that provide dignity to those who are forcibly displaced.

Syndromic surveillance of respiratory infections during protracted conflict: experiences from northern Syria 2016-2021

OBJECTIVE

Northern Syria faces a large burden of influenza-like illness (ILI) and severe acute respiratory illness (SARI). This study aimed to investigate the trends of Early Warning and Response Network (EWARN) reported ILI and SARI in northern Syria between 2016 and 2021 and the potential impact of SARS-CoV-2.

METHODS

We extracted weekly EWARN data on ILI/ SARI and aggregated cases and consultations into 4-week intervals to calculate case positivity. We conducted a seasonal-trend decomposition to assess case trends in the presence of seasonal fluctuations.

RESULTS

It was observed that 4-week aggregates of ILI cases (n = 5,942,012), SARI cases (n = 114,939), ILI case positivity, and SARI case positivity exhibited seasonal fluctuations with peaks in the winter months. ILI and SARI cases in individuals aged ≥5 years surpassed those in individuals aged <5 years in late 2019. ILI cases clustered primarily in Aleppo and Idlib, whereas SARI cases clustered in Aleppo, Idlib, Deir Ezzor, and Hassakeh. SARI cases increased sharply in 2021, corresponding with a severe SARS-CoV-2 wave, compared with the steady increase in ILI cases over time.

CONCLUSION

Respiratory infections cause widespread morbidity and mortality throughout northern Syria, particularly with the emergence of SARS-CoV-2. Strengthened surveillance and access to testing and treatment are critical to manage outbreaks among conflict-affected populations.

Dynamic mapping of cholera outbreak during the Yemeni Civil War, 2016-2019

Widespread destruction from the Yemeni Civil War (2014-present) triggered the world's largest cholera outbreak. We compiled a comprehensive health dataset and created dynamic maps to demonstrate spatiotemporal changes in cholera infections and war conflicts. We aligned and merged daily, weekly, and monthly epidemiological bulletins of confirmed cholera infections and daily conflict events and fatality records to create a dataset of weekly time series for Yemen at the governorate level (subnational regions administered by governors) from 4 January 2016 through 29 December 2019. We demonstrated the use of dynamic mapping for tracing the onset and spread of infection and manmade factors that amplify the outbreak. We report curated data and visualization techniques to further uncover associations between infectious disease outbreaks and risk factors and to better coordinate humanitarian aid and relief efforts during complex emergencies.

Critical Periods, Critical Time Points and Day-of-the-Week Effects in COVID-19 Surveillance Data: An Example in Middlesex County, Massachusetts, USA

Critical temporal changes such as weekly fluctuations in surveillance systems often reflect changes in laboratory testing capacity, access to testing or healthcare facilities, or testing preferences. Many studies have noted but few have described day-of-the-week (DoW) effects in SARS-CoV-2 surveillance over the major waves of the novel coronavirus 2019 pandemic (COVID-19). We examined DoW effects by non-pharmaceutical intervention phases adjusting for wave-specific signatures using the John Hopkins University’s (JHU’s) Center for Systems Science and Engineering (CSSE) COVID-19 data repository from 2 March 2020 through 7 November 2021 in Middlesex County, Massachusetts, USA. We cross-referenced JHU’s data with Massachusetts Department of Public Health (MDPH) COVID-19 records to reconcile inconsistent reporting. We created a calendar of statewide non-pharmaceutical intervention phases and defined the critical periods and timepoints of outbreak signatures for reported tests, cases, and deaths using Kolmogorov-Zurbenko adaptive filters. We determined that daily death counts had no DoW effects; tests were twice as likely to be reported on weekdays than weekends with decreasing effect sizes across intervention phases. Cases were also twice as likely to be reported on Tuesdays-Fridays (RR = 1.90–2.69 [95%CI: 1.38–4.08]) in the most stringent phases and half as likely to be reported on Mondays and Tuesdays (RR = 0.51–0.93 [0.44, 0.97]) in less stringent phases compared to Sundays; indicating temporal changes in laboratory testing practices and use of healthcare facilities. Understanding the DoW effects in daily surveillance records is valuable to better anticipate fluctuations in SARS-CoV-2 testing and manage appropriate workflow. We encourage health authorities to establish standardized reporting protocols.

Signatures of Cholera Outbreak during the Yemeni Civil War, 2016-2019

The Global Task Force on Cholera Control (GTFCC) created a strategy for early outbreak detection, hotspot identification, and resource mobilization coordination in response to the Yemeni cholera epidemic. This strategy requires a systematic approach for defining and classifying outbreak signatures, or the profile of an epidemic curve and its features. We used publicly available data to quantify outbreak features of the ongoing cholera epidemic in Yemen and clustered governorates using an adaptive time series methodology. We characterized outbreak signatures and identified clusters using a weekly time series of cholera rates in 20 Yemeni governorates and nationally from 4 September 2016 through 29 December 2019 as reported by the World Health Organization (WHO). We quantified critical points and periods using Kolmogorov–Zurbenko adaptive filter methodology. We assigned governorates into six clusters sharing similar outbreak signatures, according to similarities in critical points, critical periods, and the magnitude of peak rates. We identified four national outbreak waves beginning on 12 September 2016, 6 March 2017, 28 May 2018, and 28 January 2019. Among six identified clusters, we classified a core regional hotspot in Sana’a, Sana’a City, and Al-Hudaydah—the expected origin of the national outbreak. The five additional clusters differed in Wave 2 and Wave 3 peak frequency, timing, magnitude, and geographic location. As of 29 December 2019, no governorates had returned to pre-Wave 1 levels. The detected similarity in outbreak signatures suggests potentially shared environmental and human-made drivers of infection; the heterogeneity in outbreak signatures implies the potential traveling waves outwards from the core regional hotspot that could be governed by factors that deserve further investigation.

Increase in vector-borne disease reporting affecting humans and animals in Syria and neighboring countries after the onset of conflict: A ProMED analysis 2003-2018

OBJECTIVES

The protracted and violent conflict in Syria has resulted in large-scale displacement of people and destruction of health and sanitation infrastructure. The aim of this study was to examine epidemiological trends in vector-borne disease (VBD) outbreaks before and following the onset of the Syrian conflict (2011).

METHODS

ProMED, a digital disease surveillance tool, was queried for VBD outbreak reports affecting humans and animals in Syria and select bordering countries between 2003 and 2018. Data were normalized by dividing the number of unique VBD events by the total number of unique outbreak events reported by ProMED for each year. Suspected and confirmed case counts and deaths were manually extracted.

RESULTS

Reports on VBDs increased from a mean of 2.9/year pre-2011 to 12.8/year post-2011, a 343.5% (p < 0.05) increase. After normalization, reports increased by 485.5% (p < 0.05) over the time periods. Post-2011, the most commonly reported VBDs were leishmaniasis, Crimean-Congo hemorrhagic fever, and lumpy skin disease. Reported numbers of suspected and confirmed cases and deaths increased during the conflict period.

CONCLUSIONS

VBD outbreak events in ProMED increased in Syria and select bordering countries after the onset of the Syrian conflict in 2011. Enhanced disease surveillance is critical to detect and manage outbreaks in conflict settings.