Zika in Singapore: Implications for Saudi Arabia

Background On 31 August 2016, the Singapore Ministry of Health and the National Environment Agency confirmed a cluster of new infections related to the Zika virus. As of 11 October 2016, 404 cases of Zika virus infections, including 8 cases among pregnant women, were confirmed by the Singapore authorities (1,2). Further, the first pregnant woman in Singapore to be infected with Zika has been identified, living in the south-east part of the state, where other Zika cases had already been identified. Malaysia documented its first Zika infection the next day, Thursday 1 September 2016, indicating the virus had already crossed the border. The Malaysian woman infected had recently visited her daughter, a resident in Singapore, who also tested positive for Zika infection. As Zika is surging at this key international hub, the wider region of Asia is on high alert for potential transmission of the virus to the Arabian Peninsula. Certainly Singapore, a tropical island, is well acquainted with mosquito-borne infections, most notably dengue fever, which shares the same vectors as Zika, Aedes aegypti and Aedes albopictus (3). Recognition is growing that dengue-affected areas can expect and indeed should plan for unfolding Zika outbreaks. Particularly worrisome for Singapore is that over the first 9 months of 2016 a cumulative total of 12 032 cases of dengue fever were notified to the Ministry of Health, suggesting Zika numbers could be equally high, both adding to morbidity and mortality, but also confounding the diagnosis of both conditions. Zika virus and Saudi Arabia In Saudi Arabia the situation is being very closely watched. Global travel of an infected person is a likely mechanism for spreading the pathogen to new territories. In Saudi Arabia dengue virus (DEN-1, DEN-2, DEN-3) was first detected in Jeddah in 1994 and Aedes aegypti was implicated (4,5). After a large outbreak of dengue in Mecca in 2009 the disease became endemic in the city (6). Saudi Arabia is host to tens of millions of Muslims for religious tourism at Mecca, and 6 weeks ago, with the completion of the 2016 annual Hajj pilgrimage, the country had received a total of 1 325 372 international travellers, including from Singapore, Malaysia and neighbouring Indonesia, the most populous Muslim-majority nation in the world. Should Zika impact Indonesia, Saudi Arabia will be particularly threatened. Certainly the numbers of pilgrims traveling to Saudi Arabia from these countries are sobering: while only 100 pilgrims travel from Singapore to Hajj, over 15 000 arrive from Malaysia, and Indonesia sends almost 200 000 to every Hajj, where approximately 2-3 million Muslims gather. A further 6 million Muslims attend Umrah, the minor pilgrimage, most often performed in the months leading up to Hajj (the Hajj season), among whom many tens of thousands of Indonesians can also be expected. For these reasons, should Zika make the leap to Indonesia, the world's fourth most populated country (247 million), Saudi Arabia can expect significant outbreaks of Zika virus infection within a short time frame. In some ways, although the Hajj Healthcare and Emergency Management System is seasoned at managing epidemics, outbreaks and even national effects of global pandemics which coincide with Hajj season, we are certainly fortunate that this year Hajj was a huge success. Next year we may not be so lucky. Zika poses particular challenges to Indonesia: first the assumed lack of population immunity among Indonesians can be expected to lead to significant widespread acute infections among all ages groups. In Indonesia, other arboviral infections (e.g. dengue and chikungunya) are commonly encountered, distinguishing Zika infection may be difficult or delayed and matters could be further complicated by co-infection. Similarities to these other pathogens could be one reason why Zika has not been so frequently reported in Asia in the past when Zika expanded from equatorial Africa to Equatorial Asia between 1969 and 1983. …