Key Words  
  Rats, fleas, mites, lice, helminths
  Amos Wilamowski, Shumel Moran and Zalan Greenburg
  New findings on the geographical distribution and ecto- and endoparasites of Rattus norvegicus, Rattus rattus, and Mus musculuswere recorded in 1999-2000. Seven specimens ofR. rattuswere trapped in the coastal plain of Israel, six of these in the Haifa area and one in Tel Aviv. Up to this record, the coastal plain was known to harbor only R. norvegicus. An adultR. norvegicus was trapped in Jerusalem, a new record of this species inland. The rat flea,Xenopsylla cheopis, is a parasite of R. norvegicusin Israel, and its known geographical distribution was, till now, the coastal plain. X. cheopis is the vector of murine typhus, a few cases of which are recorded each year only in the coastal plain. One specimen ofR. norvegicus trapped in Tel Aviv was infested with a singleX. cheopis. This level of infestation of 0-1 fleas per rat is in accordance with the infestation index recorded in Israel since the beginning of the 1980s. One specimen of X. cheopiswas recorded on the R. norvegicustrapped in Jerusalem, possibly indicating a changing distribution pattern of the rat flea, together with the invasion of R. norvegicusto the inland areas. The most worrying finding was 31 rat fleas recorded on a single R. norvegicusin the Lod area. Such a high infestation level has not been observed in Israel since the 1960s, posing a threat to public health. Only a few mite specimens were found on both rat species. A large population of rat lice, Polyplax spinulosa, was found on R. rattus from the village of Yesodot. Such lice are not a direct danger to man, but it has been shown that they have great epidemiological importance in transferring murine typhus among rats, thus perpetuating the disease cycle. Ten different species of helminths were identified from R. rattusand six were recorded from M. musculus. The incidence of infection in R. rattus was found to be relatively small (38.5%). Bacteriological examination of 37 specimens of commensal rodents revealedCampylobacter jejuni in only four specimens of R. rattus. No Salmonella was found. This is the first record of bacteriological testing ofR. rattusin Israel. The changing patterns of geographical distribution and parasite infestation of commensal rodents since the 1950s is discussed.