Epidemic infections and their relevance to the Gulf and other Arabian Peninsula countries.

Department of Medicine, College of Medicine and Health Sciences, Sultan Qaboos University, PO Box 35, Al-Khod-123, Sultanate of Oman. Email: [email protected] THE STRATEGIC LOCATION OF THE ARABIAN Peninsula between Africa, Asia and Europe, has since early historical times drawn travellers, seafarers, and merchants to this part of the Middle East. It is inevitable that importation of communicable diseases should be a feature of such population movements. In Saudi Arabia, this has been demonstrated repeatedly over past decades, with epidemics occurring during the annual Hajj, when over a million pilgrims from more than 80 countries congregate together with a similar number of local worshippers for a week in Mecca and Medina. Plague used to break out almost every year until 98,1 and other frequent outbreaks have included smallpox,2 cholera,3 and meningococcal infection.3,4 The latter has continued to pose a problem despite the use of bivalent (A,C) vaccination for intending pilgrims, and two recent meningococcal outbreaks in 2000 and 200 caused by new serogroups required planning to introduce quadrivalent (A,C,Y, W35) vaccination in the future.5 All Arabian Peninsula countries have been subject to outbreaks of introduced communicable diseases caused by various micro-organisms, although these have not always been so well documented as the Saudi epidemics. Parasitic infections have not posed a significant threat in recent decades except perhaps, falciparum malaria. It likely that malaria was introduced to the western region of Saudi Arabia and the United Arab Emirates in the very remote past since a large proportion of inhabitants of oases have one or more red cell markers which confer resistance, e.g., thalassaemia or the sickle cell trait.3 Suitable Anopheles mosquito vectors are present in all countries in the region. Although effective malaria-control programmes have been implemented in most countries in the region, the emergence of chloroquine-resistant falciparum malaria contracted overseas has created a new concern, and this has been noted in Saudi Arabia,3 Kuwait,6 Oman,7 and the United Arab Emirates.8 Leishmaniasis occurs widely in the Middle East. The cutaneous form causes minor morbidity in a relatively immune population, but the occasional complication of systemic infection, especially in the non-immune, became significant during Operation Desert Storm when eight American servicemen stationed in the Eastern Province of Saudi Arabia developed visceral leishmaniasis after Leishmania tropica infection.9 The usual species causing visceral leishmaniasis or kala azar in the Middle East is L. infantum. (This is the probable cause of kala azar in Oman.10) As a result of exposure of overseas troops to sandfly vectors of leishmaniasis during the recent war in Iraq, thousands of potential blood donors among the American troops were excluded as future donors. It is probable that schistosomiasis mansoni and haematobium which are widely prevalent in the Middle East, were introduced from the Nile Valley of Egypt in prehistoric times to Saudi Arabia, Yemen and probably Oman.11 Snail vector control programmes in most countries have limited transmission, but the need to implement vector control indefinitely was demonstrated recently in Dhofar province in Oman, when suspension of regular mollusciciding resulted in a new epidemic of schistosomiasis mansoni.12 Bacterial infections of potential epidemic significance to the Arabian Peninsula other than meningococcus infection, are few. Small outbreaks of typhoid fever are not infrequent, but do not pose a major community threat. Cholera has been introduced sporadically, e.g. by illegal immigrants from Pakistan and Afghanistan in Oman in 2000, and occasionally in other countries. In Scrimgeour editorial