Invasive Species Compendium

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Abstract

Transmission of the agent of Lyme disease on a subtropical island.

Abstract

To determine whether the agent of Lyme disease (Borrelia burgdorferi) perpetuates on a subtropical island, prevalence of spirochaetal infection in Ixodes ricinus ticks collected on Madeira Island was recorded and local reservoir hosts of both pathogen and vector tick identified. Spirochaetes infected at least 1.3% of the nymphal ticks collected in a particular site. Subadult ticks frequently parasitized Norway rats (Rattus norvegicus) as well as black rats (R. rattus) on the island, and Lyme disease spirochaetes were found in these hosts. Each was competent as reservoir host. Canaries (Serinus canaria), lizards (Podarcis dugesii) and domestic ungulates (calves and sheep), on the other hand, were incompetent for Madeiran spirochaetal isolates. Madeiran spirochaetes stimulated rodents to recognize the same antigens as did spirochaetes isolated on the European continent. The polymerase chain reaction amplified identical specific sequences of Madeiran spirochaetes as of European-derived spirochaetes. Rats appear to be the main reservoir hosts of the agent of Lyme disease on Madeira, and cattle and sheep serve as definitive hosts of the vector tick. The agent of Lyme disease is enzootic on this subtropical island some 10° of latitude south of the northern Mediterranean coast. Because I. ricinus frequently attacks people on Madeira, Lyme disease should be considered as a cause of locally acquired human illness.newline˜From AS<new para>ADDITIONAL ABSTRACT:<new para>To determine whether the agent of Lyme disease (Borrelia burgdorferi) perpetuates on a subtropical island, prevalence of spirochaetal infection in Ixodes ricinus ticks collected on Madeira Island was recorded and local reservoir hosts of both pathogen and vector tick identified. Spirochaetes infected at least 1.3% of the nymphal ticks collected in a particular site. Subadult ticks frequently parasitized Norway rats (Rattus norvegicus) as as well black rats (R. rattus) on the island, and Lyme disease spirochaetes were found in these hosts. Each was competent as reservoir host. Canaries (Serinus canaria), lizards (Podarcis dugesii) and domestic ungulates (calves and sheep), on the other hand, were incompetent for Madeiran spirochaetal isolates. Madeiran spirochaetes stimulated rodents to recognize the same antigens as did spirochaetes isolated on the European continent. The polymerase chain reaction amplified identical specific sequences of Madeiran spirochaetes as of European-derived spirochaetes. Rats appear to be the main reservoir hosts of the agent of Lyme disease on Madeira, and cattle and sheep serve as definitive hosts of the vector tick. The agent of Lyme disease is enzootic on this subtropical island some 10° of latitude south of the northern Mediterranean coast. Because I. ricinus frequently attacks people on Madeira, Lyme disease should be considered as a cause of locally acquired human illness.