The global eradication of poliomyelitis, believed to be achievable around the year 2000, relies on strategies which include high routine immunization coverage and mass vaccination campaigns, along with continuous monitoring of wild-type virus circulation by using the laboratory-based acute flaccid paralysis (AFP) surveillance. Israel and the Palestinian Authority are located in a geographical region in which poliovirus is still endemic but have been free of poliomyelitis since 1988 as a result of intensive immunization programs and mass vaccination campaigns. To monitor the wild-type virus circulation, environmental surveillance of sewage samples collected monthly from 25 to 30 sites across the country was implemented in 1989 and AFP surveillance began in 1994. The sewage samples were processed in the laboratory with a double-selective tissue culture system, which enabled economical processing of large number of samples. Between 1989 and 1997, 2,294 samples were processed, and wild-type poliovirus was isolated from 17 of them in four clusters, termed “silent outbreaks,” in September 1990 (type 3), between May and September 1991 (type 1), between October 1994 and June 1995 (type 1), and in December 1996 (type 1). Fifteen of the 17 positive samples were collected in the Gaza Strip, 1 was collected in the West Bank, and 1 was collected in the Israeli city of Ashdod, located close to the Gaza Strip. The AFP surveillance system failed to detect the circulating wild-type viruses. These findings further emphasize the important role that environmental surveillance can play in monitoring the eradication of polioviruses.
Kaposi's sarcoma of the gingiva and skin developed in an HIV-negative renal transplant patient while he was receiving cyclosporine therapy. The Kaposi's sarcoma developed shortly after the patient had an acute infection with cytomegalovirus (CMV). Electron microscopy of the tumor's established cell line showed two types of virus-like particles. CMV DNA was identifiable in the cell line whereas infectious CMV could be isolated only after repeated passages (only after 3 months of culture). The other virus could not be identified, but did not appear to be either HIV or papilloma virus. The patient's tumor regressed after the discontinuation of cyclosporine therapy and the recovery from the acute CMV infection.
An outbreak of poliomyelitis with 20 cases occurred in Israel, Gaza, and the West Bank from October 1987 to October 1988. The wild type 1 poliovirus associated with the outbreak was most closely related to viruses found in the Nile Delta. The epidemiologic links among patients involved in the outbreak and patients with community-acquired infections during the outbreak were inferred from the evolutionary relationships among isolates of the outbreak virus. Complete VP1 sequences (906 nucleotides) were determined for 12 clinical and 4 sewage isolates. A total of 58 nucleotide differences were found among the 16 isolates; 74% of all substitutions were synonymous third-position transitions. An evolutionary tree, representing both the pathways of VP1 sequence evolution and the inferred chains of virus transmission during the outbreak, was constructed under the assumption that each substitution had occurred only once. The combined epidemiologic and molecular data suggest that a single founder strain was introduced into Israel from the vicinity of Gaza in the fall of 1987. Poliovirus circulation was apparently localized to southern communities during the winter and spread north by the following summer into the Hadera subdistrict of Israel, where it radiated via multiple chains of transmission into other communities in northern Israel and the West Bank. The close sequence matches (>99%) between clinical and sewage isolates from the same communities confirm the utility of environmental sampling as a tool for monitoring wild poliovirus circulation.
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