Open Access Volume: 41, Article ID: e2019015, 6 pages https://doi.org/10.4178/epih.e2019015 ORIGINAL ARTICLE Risk factors associated with the recent cholera outbreak in Yemen: a case-control study Fekri Dureab1, Albrecht Jahn2, Johannes Krisam3, Asma Dureab4, Omer Zain5, Sameh Al-Awlaqi1,6, Olaf Müller2 1The Modern Social Association, Aden, Yemen; 2Heidelberg Institute of Global Health, Heidelberg University School of Medicine, Heidelberg, Germany; 3Institute of Medical Biometry and Informatics, Heidelberg University School of Medicine, Heidelberg, Germany; 4Health and Education Association for Development (SAWT), Aden, Yemen; 5Community Medicine Department, Faculty of Medicine, University of Aden, Aden, Yemen; 6Institute of Public Health, Jagiellonian University Medical College, Krakow, Poland OBJECTIVES: The cholera outbreak in Yemen has become the largest in the recent history of cholera records, having reached more than 1.4 million cases since it started in late 2016. This study aimed to identify risk factors for cholera in this outbreak. METHODS: A case-control study was conducted in Aden in 2018 to investigate risk factors for cholera in this still-ongoing outbreak. In total, 59 cholera cases and 118 community controls were studied. RESULTS: The following risk factors were associated with being a cholera case in the bivariate analysis: a history of travelling and having had visitors from outside Aden Province; eating outside the house; not washing fruit, vegetables, and khat (a local herbal stimulant) before consumption; using common-source water; and not using chlorine or soap in the household. In the multivari- ate analysis, not washing khat and the use of common-source water remained significant risk factors for being a cholera case. CONCLUSIONS: Behavioural factors and unsafe water appear to be the major risk factors in the recent cholera outbreak in Yemen. In order to reduce the risk of cholera, hygiene practices for washing khat and vegetables and the use and accessibility of safe drinking water should be promoted at the community level. KEY WORDS: Cholera, Case-control studies, Risk factors, Conflict, Khat, Yemen INTRODUCTION diarrhoea or vomitus. The first cholera pandemic began in 1817, and the current (seventh) pandemic started in 1961in Indonesia Cholera continues to be a significant public health problem in and is caused by the El Tor biotype. After starting in Indonesia, it many developing countries. It manifests as an acute watery diar- spread to Asia, Africa, Europe, the Middle East, and Latin Ameri- rhoeal disease, and it is mainly transmitted through the faecal-oral ca [1]. route by contaminated water or food. The disease is caused by the Yemen is situated in southwest Asia on the Arabian Peninsula. bacterium Vibrio cholerae. It is considered to be laboratory-con- The country has a diverse topography, with mountainous areas in firmed when V. cholerae O1 or O139 is detected in any patient’s the north, desert in the east, and a coastal landscape in the south and the west. The country is divided administratively into 23 gov- Correspondence: Fekri Dureab ernorates (provinces) and 333 districts. The population of Yemen The Modern Social Association, P. O. Box 12567, Aden, Yemen is more than 30 million as of 2017 [2]. Yemen is the most impov- E-mail: [email protected] erished country in the Arabian Peninsula and among the poorest Received: Mar 21, 2019 / Accepted: Apr 21, 2019 / Published: Apr 21, 2019 worldwide, with a gross domestic product (GDP) of US$ 1,106 [3]. This article is available from: http://e-epih.org/ The country is furthermore burdened by low literacy rates, poor This is an open-access article distributed under the terms of the Creative governance, a high prevalence of poverty, frequent food insecurity, Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, and widespread malnutrition [4]. provided the original work is properly cited. The emergence of the armed conflict in March 2015 in Yemen 2019, Korean Society of Epidemiology has exacerbated the already critical economic, political, and hu- www.e-epih.org | 1 Epidemiol Health 2019;41:e2019015 manitarian situation that had prevailed for more than a decade. resulted in further disruption of many healthcare services and Approximately 4 years into the conflict, the country’s GDP has poses a major threat to Yemen’s public health [12]. The conflict contracted by more than 42%, and the humanitarian situation has has led to fragmentation of the health system, with two independ- been further aggravated by increased fighting, population displace- ent ministries for health operational in each region of the country ment, the lack of basic commodities and services, and an accom- (the rebels are seizing the north, while the legitimate government panying overall breakdown of public and social services [5]. controls the southern region). This fragmentation has negatively The occurrence of epidemics, especially cholera, is known to be impacted the health system and the delivery of essential health an obvious sign of the disruption of basic services [6]. Several chol- services [13]. era outbreaks have occurred during the last 10 years in Yemen; The cholera outbreak in Yemen is the largest in the recent histo- there were 3 smaller outbreaks in 2009, 2010 and 2011, with case ry of this disease. The magnitude of this outbreak can probably be fatality rates (CFRs) of 5.5%, 1.3%, and 0.4%, respectively [7-9]. explained by the overall breakdown of public services, including The most recent outbreak started in October 2016, with 1,423,700 hygiene and sanitation, associated with the war in Yemen. How- suspected cases and 4,510 laboratory-confirmed cases reported ever, evidence on specific risk factors is needed to guide an appro- from 306 of 333 districts through January 2019; these cases have priate public health response. This study aimed to identify such resulted in 2,767 deaths, corresponding to a CFR of 0.2% [10]. risk factors for the recent large cholera outbreak in Yemen. The war in Yemen has left 18.8 million people in need of assis- Khat (Catha edulis) is a flowering plant that grows in the horn tance or protection, including the need for access to safe drinking of Africa and in Yemen. It is socially accepted in Yemen, and its water and sanitation, and an estimated 14.8 million people have green leaves are regularly chewed by the majority of people and no or limited access to basic healthcare. Moreover, there is a chron- used as a cognitive stimulant. The amphetamine-like alkaloid cathi- ic shortage of medical supplies, and about half of the health facili- none in khat is known to cause excitement, loss of appetite, and ties are no longer functional [11]. Public health facilities have been euphoria [14]. As there have been rumours that using khat could severely weakened by the escalating conflict, which has been com- be associated with the cholera outbreak, this study included the pounded by the financial crisis of the Ministry of Public Health use of khat as a potential risk factor. and Population (MoPHP). The lack of an operational budget has Figure 1. Map of Aden. 2 | www.e-epih.org Dureab F et al. : Risk factors associated with the recent cholera outbreak MATERIALS AND METHODS nomic information and on possible cholera risk factors such as handwashing practices, water sources, treatment and storage of Study design and procedures drinking water, sources of food, hygiene and sanitation practices, We reviewed the cholera outbreak line list of the MoPHP sur- khat chewing, and attendance at ceremonies. veillance department in Aden, Yemen, from January 1 until March 31, 2018. The department is part of the health authorities of the Data analysis Aden Province (Figure 1), and collects data on communicable Data were entered into Excel spreadsheets, and all data were diseases. The variables recorded in the line list were name, age, checked and cleaned by the local field supervisor. Double-check- sex, residence, date of onset of diarrhoea, date of treatment or ad- ing was done by the principal investigator (FD). Exposure-related mission to a health facility, and outcome status. variables were included in the logistic regression analysis used in This case-control study was conducted from April 1 to 30, the multivariate model if they displayed a p-value< 0.05 in the bi- 2018. A case was defined as any person suffering from watery di- variate analysis. We calculated the ORs and 95% CIs associated arrhoea between January 1 and March 31, 2018, whose illness was with the independent variables. Data were analysed using SPSS confirmed as cholera based on a laboratory analysis (isolation of V. version 25.0 (IBM Corp., Armonk, NY, USA). cholerae serotypes 01 or 0139 in stool culture). Further inclusion criteria were being a resident of Aden and age ≥ 2 years because Ethics statement cholera is not common in children younger than 2 years [15]. The Formal permission to conduct this study was obtained from controls were defined as members of the same community with the MoPHP Ethical Committee in Aden, Yemen. All participants an absence of diarrhoea between January 1 and March 31, 2018. provided oral and written informed consent before the interview. Two controls were matched to each case by sex and residence For participants below 18 years of age, parents or guardians grant- (district) from 7 out of the 8 districts in Aden Province (Table 1). ed consent on their behalf and accompanied them during the in- The 2 controls were randomly selected from the 10 households to terview. No identifiable personal data were associated with the the right and to the left of the household of the case, respectively. reported results, as the questionnaires were coded by numbers If there was more than 1 person of the same sex as the case in a only.