zoonoses and communicable diseases common to ... - PAHO/WHO

LYME DISEASE 179World Health Organization (WHO). Outbreak of listeriosis in 1992. Wkly Epidemiol Rec68(13):89–91, 1993.Young, S. Listeriosis in cattle and sheep. In: Faulkner, L.C., ed. Abortion Diseases ofLivestock. Springfield: Thomas; 1968.LYME DISEASEICD-10 A69.2Synonyms: Lyme borreliosis, Lyme arthritis, erythema migrans (formerly erythemachronicum migrans) with polyarthritis.Etiology: The etiologic agent is a spirochete, transmitted by ticks of the Ixodesricinus complex and named Borrelia burgdorferi in honor of the person who discoveredit (Burgdorfer et al., 1982; Steere et al., 1983; Johnson et al., 1984). Thegenus Borrelia belongs to the family Spirochaetaceae and is made up of spiralshaped,actively motile bacteria. B. burgdorferi is 11 to 39 microns long and has 7to 11 flagella. The strains of B. burgdorferi isolated in Europe have demonstratedsome heterogeneity, particularly in the two principal plasmid-dependent surface proteins(Steere, 1990).Geographical Distribution and Occurrence in Man: The human disease hasbeen recognized in 46 states in the US. Areas with endemic foci in that country arethe Atlantic coast (particularly in the Northeast), Wisconsin and Minnesota in theMidwest, and California and Oregon along the Pacific coast (Benenson, 1990). Thenatural foci of the infection are expanding. In New York State, the number of countieswith recorded human cases increased from four to eight between 1985 and 1989and the number of counties where the presence of the tick Ixodes dammini, the vectorof the infection, was documented increased from 4 to 22 during the same period(White et al., 1991). 1 In the US, more than 40,000 cases were recorded between1982 and 1992, and it is currently the principal disease transmitted by ticks. Themajor vectors of the infection in the US are Ixodes dammini in the East andMidwest, and I. pacificus on the Pacific coast.The etiological agent has also been isolated in Ontario (Canada). Many Europeancountries record cases of Lyme borreliosis and the vector on that continent is Ixodesricinus. The disease has also been recognized in Australia, China, Japan, and coun-1A study indicates that Ixodes dammini and I. scapularis (a tick in the southern US) aregeographic variants of the same species, which would correctly be named I. scapularis (Oliveret al., 1993). Since there are differences in terms of ecology and the rate of infection(Kazmierczak and Sorhage, 1993), we feel it is advisable to retain the terminology commonlyin use for both varieties in order to avoid confusion.