Virology tidbits

Virology tidbits

Wednesday, 16 April 2014

Polio in the Middle East - a tinderbox

Apart from MERS another viral disease is spreading in the Middle East: Poliomyelitis.
Poliomyelitis -or Polio for short- is recognised as a disease affecting the spinal cord since 1789 and known to have appeared in epidemics on a global scale until the vaccination became available in the 1950s. Following mass vaccination campaigns the disease was eliminated from the United States and Europe in the mid1970s and from the Middle East in the 1980s, leaving some African countries and swaths of Afghanistan and Pakistan as pockets. In the year 2000, annual cases (worldwide) were less than 1000 -down from an estimated 600000 prior to the arrival of the Polio vaccine. Wild type II Poliovirus was eradicated in 1999, but both Poliovirus type I and III continue to circulate in four countries in Asia and Africa, causing sporadic outbreaks and transmission not only in endemic areas but also those which have been declared free of Polio.
One of these previously Polio free area is Syria, which introduced mass vaccination campaigns in the 1980s (mirrored by similar campaigns in Iraq and Lebanon). 
Polio vaccination rates and cases 1980-2012 (Source: WHO)

As it is well known Syria is ravaged by a civil war, which not killed an estimated 140000 people but also displaced 8 to 9 million people. These refugees often flee to the neighboring countries of Lebanon, Jordan and Iraq where they are confined to cramped refugee camps. These camps often do not have running water and only rudimentary sewage disposal system, which often overflow with the rain. It is not surprising therefore that diarrhea, respiratory diseases, Hepatitis A, scabies and lice are common diseases are particular common among the children which are not only traumatized but also often malnourished. These conditions are also a breeding ground for a resurgence of Polio, a disease transmitted via the oral-fecal route. Indeed, first cases of Polio from Syria were reported in October 2013 from the Deir Al Zour province region bordering Iraq and the region around Aleppo/Edleb in the east (bordering Lebanon). As for the refugee camps, a first unconfirmed case has been reported from a refugee camp in Taanayel/Lebanon. Furthermore, Israel reported in 2013 25 cases of Polio being identified in samples of sewage - so far however no human case has been reported and no link to the outbreak in Syria has been established. The lack of human cases might be attributed to widespread of inactivated Polio vaccine (Salk vaccine) and the high herd immunity in Israel.
Given that mass vaccinations campaigns were conducted in Syria until 2012 it is possible that a larger epidemic among Syrian refugees might have been prevented so far thanks to past immunization. Inside Syria, a mass vaccination campaign in 2012 excluded the rebel stronghold of Deir Al Zou a region that reported the first cases of Polio ten months later. This is mirrored by the resurgence of Polio in the region of Aleppo, another heavily contested area in the conflict. In the past, mass vaccination campaigns in other conflict areas were only possible due to the willingness of the parties involved to allow vaccinators into contested areas. Let’s hope that this time this is the case as well. Until then mass vaccination campaigns are imperative in refugee camps to maintain high herd immunity. Highlighting the need of vaccination campaigns is the identification of a case of Polio in Iraq, which has been linked to the outbreak in Syria.

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