Fleas on Roof Rats in Six Areas of Los Angeles County, California: Their Potential Role in the Transmission of Plague and Murine Typhus to Humans

Tom G. SchwanVector Biology and Control Branch, California Department of Health Services, 2151 Berkeley Way, Berkeley, California 94704

Search for other papers by Tom G. Schwan in
Current site
Google Scholar
PubMed
Close
,
Donald ThompsonVector Control Program, Los Angeles County Department of Health, 313 North Figuroa Street, Los Angeles, California 90012

Search for other papers by Donald Thompson in
Current site
Google Scholar
PubMed
Close
, and
Bernard C. NelsonVector Biology and Control Branch, California Department of Health Services, 2151 Berkeley Way, Berkeley, California 94704

Search for other papers by Bernard C. Nelson in
Current site
Google Scholar
PubMed
Close
Restricted access

Roof rats (Rattus rattus) in southern California are rarely involved with plague epizootics and murine typhus. Little evidence exists implicating these rodents as sources of human infection. This might be explained by the absence of fleas capable of transmitting these 2 diseases. From February 1981 through January 1982, roof rats were live-trapped and examined for fleas each month in 4 areas of Los Angeles County. Two other areas were trapped for 9 and 3 months respectively. Areas sampled were in or near the suburban-wilderness fringe where plague and murine typhus occur, and where roof rats coexist with a variety of wild and domestic mammals and humans. From 1,206 roof rats, 827 fleas belonging to eight species were collected. Leptopsylla segnis (54%) and Nosopsyllus fasciatus (39%) were the most abundant and together comprised 93% of all fleas. Xenopsylla cheopis was not found. The relative abundance and diversity of fleas on roof rats varied considerably between areas, making it difficult to predict flea diversity and abundance in unsurveyed areas where similar conditions exist. However, the overall low flea indices and the absence of X. cheopis help to explain why roof rats in Los Angeles County are rarely involved with plague and murine typhus.

Author Notes

Present address: Yale Arbovirus Research Unit, Yale University School of Medicine, P.O. Box 3333, 60 College Street, New Haven, Connecticut 06510. Send reprint requests to this address.

Save