A retrospective analysis of oral cholera vaccine use, disease severity and deaths during an outbreak in South Sudan.

Cavin Epie Bekolo,Otim Patrick Ramadan,Debarati Guha-Sapir,Joris Adriaan Frank Van Loenhout,Jose Manuel Rodriguez-Llanes,John Rumunu

doi:10.2471/blt.15.166892

Cavin Epie Bekolo, Otim Patrick Ramadan + Show 4 more

Open Access

https://doi.org/10.2471/blt.15.166892

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Abstract

ObjectiveTo determine whether pre-emptive oral cholera vaccination reduces disease severity and mortality in people who develop cholera disease during an outbreak.MethodsThe study involved a retrospective analysis of demographic and clinical data from 41 cholera treatment facilities in South Sudan on patients who developed cholera disease between 23 April and 20 July 2014 during a large outbreak, a few months after a pre-emptive oral vaccination campaign. Patients who developed severe dehydration were regarded as having a severe cholera infection. Vaccinated and unvaccinated patients were compared and multivariate logistic regression analysis was used to identify factors associated with developing severe disease or death.FindingsIn total, 4115 cholera patients were treated at the 41 facilities: 1946 (47.3%) had severe disease and 62 (1.5%) deaths occurred. Multivariate analysis showed that patients who received two doses of oral cholera vaccine were 4.5-fold less likely to develop severe disease than unvaccinated patients (adjusted odds ratio, aOR: 0.22; 95% confidence interval, CI: 0.11–0.44). Moreover, those with severe cholera were significantly more likely to die than those without (aOR: 4.76; 95% CI: 2.33–9.77).ConclusionPre-emptive vaccination with two doses of oral cholera vaccine was associated with a significant reduction in the likelihood of developing severe cholera disease during an outbreak in South Sudan. Moreover, severe disease was the strongest predictor of death. Two doses of oral cholera vaccine should be used in emergencies to reduce the disease burden.

Highlights

Cholera is an extremely virulent diarrhoeal disease that affects both children and adults and can kill within hours if left untreated
Other factors independently linked to lower odds of severe disease included: (i) presentation in the second wave of the epidemic; and (ii) the absence of multiple symptoms
We found that pre-emptive vaccination with two doses of oral cholera vaccine was associated with a 4.5-fold reduction in the likelihood of developing severe cholera during an outbreak in South Sudan compared with no vaccination

Summary

Introduction

Cholera is an extremely virulent diarrhoeal disease that affects both children and adults and can kill within hours if left untreated. The disease was largely eliminated from industrialized countries over a century ago by water and sewage treatment, it remains a major cause of morbidity and mortality in many areas of Africa and Asia. There are an estimated 3 to 5 million cases and 100 000 to 120 000 deaths due to cholera.[1] Areas where minimum requirements for clean water and sanitation have not been met, such as peri-urban slums and camps for internally displaced people or refugees, are most at risk.[1,2] the attack rate of cholera is high, fewer than 25% of those infected become ill.[1] Among people who develop symptoms, 80% have mild or moderate disease, whereas around 20% develop acute watery diarrhoea with severe dehydration. As many as 80% can be treated successfully through prompt administration of oral rehydration salts and, with good or adequate fluid replacement (oral or intravenous), mortality is reduced to about 1%.3

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