The challenges of cholera at the 2017 Hajj pilgrimage

In September, 2017, up to 2 million pilgrims from all continents will arrive in Saudi Arabia for the annual Hajj pilgrimage.¹ Living and worshipping together in crowded conditions will expose the pilgrims and the local Saudi Arabian community to a range of imported and local infections.¹ Over the past 5 years the Hajj has focused attention on new and re-emerging infectious diseases with epidemic potential such as the Middle East respiratory syndrome coronavirus (MERS-CoV), Zika virus, and pan-antibiotic-resistant bacteria—global health security threats that are ongoing and under active surveillance.² This year the explosive outbreak of cholera in Yemen,³ from where many pilgrims originate, represents a serious risk to all pilgrims during the Hajj, and has the potential for global spread after the pilgrims return to their countries of origin. As of July 21, 2017, the cholera epidemic in Yemen has affected an estimated 356 600 people and caused 1800 deaths, with 5000 new active cases reported every day.⁴

Cholera at the Hajj is not new.⁵ During the 1821 Hajj, 20 000 pilgrims died as a result of the global cholera epidemic, which started in India in 1817 and spread across the world. Another cholera epidemic during the 1865 Hajj killed 15 000 of 90 000 pilgrims, and spread worldwide, including to the USA and Europe, with 200 000 deaths.⁵ Dealing with infectious disease outbreaks and outbreak prevention at the Hajj has been a public health priority for Saudi Arabia because repeated endemic outbreaks of diarrhoeal diseases have occurred as a result of various pathogens prevalent in countries from which pilgrims originate. Since the 1865 outbreak, the Saudi Arabian health authorities have been well prepared to respond to an outbreak and have not had a major cholera outbreak, largely because of improvements to infrastructures for surveillance, rapid detection, and control through the Hajj Command and Control Centre.¹ They have ensured hygienic living conditions for pilgrims, and easy and free access to washing facilities, purified water, and health services.¹

The latest overall cholera prevalence in Yemen has been estimated at 266 per 10 000 population.⁶ In 2016, 19 500 Yemenis obtained a visa for the Hajj. If the attack rate is the same in a similar number of Yemeni pilgrims planning to attend the Hajj in 2017, up to roughly 582 cases of cholera can be expected. Notably, about 80% of individuals infected with Vibrio cholerae do not show symptoms and remain undetected, but are infectious. Thus, cholera poses substantial public health challenges for the 2017 Hajj. The ongoing cholera epidemic in Yemen calls for extreme caution and requires that particular attention is given to prevention, surveillance, and control measures. Advances in the development and assessment of new cholera vaccines provide hope for better control.⁷ The WHO Strategic Advisory Group of Experts (SAGE) on immunisation⁸ concluded at their meeting in April, 2017, that there is mounting evidence over the past 3 years that high coverage with oral cholera vaccine (OCV) results in a significant reduction of cholera transmission in various settings.

Three killed whole-cell OCVs have been prequalified by WHO—Dukoral (Valneva, Stockholm, Sweden), Shanchol (Shantha Biotechnics, Hyderabad, India), and Euvichol (EuBiologics, Seoul, South Korea). All three vaccines have good safety profiles and greater than 60% effectiveness against cholera disease for at least 3 years after two doses. In 2013, WHO formally established an OCV stockpile, which consists of Shanchol and Euvichol. Thus, mandating the cholera vaccine for pilgrims from Yemen, and those countries where cholera is endemic, might be prudent and requires practical and feasible recommendations.

WHO and Saudi Arabia should jointly commission a risk assessment to review the potential benefits, risks, costs, and practicalities of cholera vaccination and come up with feasible recommendations that should be operationally, clinically, financially, and politically sustainable. These recommendations should be included in the 2017 Saudi Arabian health requirements for pilgrims.⁹ Furthermore, WHO guidelines on measures to prevent cholera and community awareness campaigns should be put into practice and strictly implemented. Proactive health education campaigns, implemented before, during, and after the Hajj, using leaflets and social media targeting all pilgrims and local Saudi Arabia populations, are required. These campaigns should include recommendations for basic hygienic toilet practice, including hand-washing after defecation and before handling food and eating, and health-seeking behaviour for those who develop symptoms. Meanwhile, the focus on cholera must not deter the Saudi Arabian authorities from remaining vigilant with regard to other epidemic-prone gastrointestinal and respiratory tract pathogens.²