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An outbreak of spotted fever group rickettsiae (SFGR) was investigated by studying free-living and parasitic stages of ticks in two settlements of equal size and population located 20 km apart in the Negev Desert. Although high morbidity from SFGR was found in one of the settlements (Kibbutz Ze'elim), no clinical cases were observed in the second (Kibbutz Re'im). Using flagging and CO2-trapping, approximately 9 times more ticks were collected in Ze'elim than in Re'im. Rhipicephalus sanguineus (Latreille) was the dominant species in Ze'elim, whereas in Re'im R. turanicus Pomerantzev was the most abundant species. Several physical factors that may account for these differences were investigated. Significantly higher maximum soil temperature as well as ambient temperature above the soil were found in Ze'elim. Differences in soil composition in the two sites were also observed. Tick numbers were especially high during April through October in Ze'elim, whereas in Re'im, ticks were found mainly from April to July. A significant positive correlation was found between temperature and tick population size in Ze'elim. Dogs, sheep, goats, Mus musculus, and Meriones crassus, were more heavily infested with ticks in Ze'elim than in Re'im. The percentage of mice and dogs seropositive to SFGR was the same in both sites. In Ze'elim, 7.1% of dog owners acquired Mediterranean spotted fever during the period 1984-1989 compared with only 1.4% of people without dogs.

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In a bluetongue (BT) disease project, light trappings of Culkoides were conducted in 19 localities and 39,000 biting midges were examined. BT virus type 16 was isolated in 1968 at Devora from a pool consisting mainly of Culicoides schultzei gp and C. imicola; BT virus type 4 was isolated in 1969 at Yesodot from a pool of 183 C. imicola; BT virus type 2 was isolated in 1979 at Talme El'azar from pools consisting of 2462 C. imicola; and BT virus type 6 was isolated 3 times in 1980 at Bet Dagan from pools of 204, 258 and from 143 C. imicola, respectively. In the Akabane project (1976 and 1977) 4632 Culicoides and 1867 mosquitoes from four localities were trapped and examined. An arbovirus which was not Akabane, BT or turkey meningo-encephalitis (TME) was isolated from a pool of 44 engorged Culex pipiens complex trapped in Gan Shemuel. In the Rift Valley fever project, which was conducted in 1978 and 1979 due to the presence of an epidemic in Egypt, 351 mosquitoes of four species and 7098Culicoides of 14 species were tested and none were found to harbour an arbovirus. Within the TME project more than 12,000 Culicoides and 9000 mosquitoes from 14 localities were tested. Positive isolations of TME were made from an unsorted pool of mosquitoes from Gesher haziw, an unsorted pool of 13 Culicoides from Nahalal, a pool of 223 unidentified Culicoides from Zetan and a pool of 12 engorged Cx pipiens complex from the same locality. Other pathogens which were not identified to species level were also isolated.

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