WHO sends mission to Israel following detection of wild poliovirus in sewage
As requested by Israeli health authorities, a team of international poliomyelitis (polio) experts, coordinated by WHO, completed a five-day mission to Israel on 26 June 2013. The team assessed the risks and recommended action following the detection of wild poliovirus type 1 (wPV1) in sewage in the Southern District of the country. No cases of paralytic polio have been detected.
Following the mission, a supplementary immunization campaign with oral polio vaccine is planned, even though Israel continues to maintain high vaccination coverage and polio immunity in the population. The decision to launch the campaign reflects both the estimated extent of circulation of the virus and the Israeli authorities’ commitment to interrupt transmission as rapidly as possible.
The virus was originally isolated from sewage samples collected in Beersheva in February 2013. Since then it has been isolated in further samples from different locations, most recently in early June. Genetic sequencing and epidemiological investigations have established that it is of the South Asian genotype and not related to the virus currently affecting the Horn of Africa. WHO experts are working with scientists from Israel’s national polio laboratory to gain further understanding of the origins of the virus.
Israel has systematically conducted environmental sampling for many years, and the poliovirus was detected thanks to this vigilance. Public health authorities continue to monitor the situation carefully, and measures have been taken to increase surveillance and reporting for possible human cases, regardless of age.
The aim of the supplementary immunization campaign is to protect any children in the country who may have missed routine vaccinations for any reason. In southern areas, adults are also being assessed and those thought to be susceptible are being immunized.
Israel’s Minister of Health, Mrs Yael German, and the Director General of the Ministry of Health, Dr Ronni Gamzu, expressed their appreciation for the mission at a press conference on Wednesday, 26 June, praising the team’s professionalism and supportiveness.
Dr Dina Pfeifer, Programme Manager for Vaccine-preventable Diseases and Immunization at WHO/Europe, acknowledged the Israeli public health authorities’ readiness to cooperate with the WHO-led mission: “We have reviewed the evidence and the steps that have been taken to date. We are thankful to the Government of Israel for their openness and we are fully committed to supporting their efforts.”
Israel and polio
Israel has been free of indigenous wPV transmission for 25 years, the last cases of paralytic polio having occurred in 1988. At that time the authorities launched a mass vaccination campaign immunizing the population aged 0–40 years with oral polio vaccine.
Risk and preparedness
Given the high level of population immunity and the continuing response to the detection of wPV in the environment, WHO assesses the risk of the further international spread of this virus strain from Israel as moderate. The relevant WHO regional offices are working closely to ensure a coordinated response in the area and neighbouring Member States.
Nevertheless, it is vital that all countries, particularly those with frequent travel and contacts with polio-affected countries, strengthen surveillance for cases of acute flaccid paralysis, to rapidly detect any new poliovirus importation and respond.
Countries should also analyse data on routine immunization coverage to identify any susceptible groups in the population. Such information can guide catch-up immunization activities and thereby minimize the consequences of new poliovirus introduction. Priority should be given to areas where the risk of importation is high and vaccine coverage is less than 80%.
WHO’s information on international travel and health recommends that all travellers to and from polio-affected areas be fully vaccinated against polio. Indigenous transmission of wPV remains endemic in 3 countries: Afghanistan, Nigeria and Pakistan. In addition, The Horn of Africa is experiencing an outbreak of wPV, with 31 cases confirmed in Kenya and Somalia.