Critical Needs and Gaps in Understanding Prevention, Amelioration, and Resolution of Lyme and Other Tick-Borne Diseases The Short-Term and Long-Term Outcomes: Workshop Report (2011) / Chapter Skim
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2 An Overview of Tick-Borne Diseases
2 An Overview of Tick-Borne Diseases
Pages 15-24
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From page 15... ...
By 1982, the Centers for Disease Control and Prevention designated Lyme disease as a notifiable disease, but even with this designation, an unknown number of cases remain unreported. Lyme disease is also found in Europe, where it is one of the fastest growing zoonotic diseases.
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From page 16... ...
In most of northeastern United States, the black-legged tick, or Ixodes scapularis, is the primary vector for the transmission of Borrelia burgdorferi, the spirochete bacterium that causes Lyme disease. The Ixodes tick is a three-host tick, and its life cycle includes three post-egg stages: larva, nymph, and adult.
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From page 17... ...
Larval ticks hatch uninfected with Lyme disease spirochetes because of the lack of transovarial transmission of the pathogen from ticks through their eggs. However, the larval ticks will feed on virtually any warmblooded vertebrate they encounter while questing on the forest floor.
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From page 18... ...
However, this is likely because humans and their pets were the only host species available on the island for adult black-legged ticks after the removal of the deer. Other studies that have controlled deer populations and monitored tick populations have found a different outcome when other host species for the black-legged tick were present.
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From page 19... ...
The whitefooted mouse grooms off and kills an average of 50 larval ticks per week, while gray squirrels groom off and kill approximately 843 larval ticks and opossums 5,686 larval ticks. These species also vary in reservoir competence, with infected whitefooted mice infecting approximately 90 percent of larval ticks that feed on them, and the other species, such as the white-tailed deer, raccoons, and opossums, infecting very few larval ticks (see Figure 2-3)
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From page 20... ...
In suburban Duchess County in southeastern New York, there was a significant negative correlation between the size of a forest fragment and the prevalence of Lyme disease infection in the nymphal tick population (Allan et al., 2003)
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From page 21... ...
However, initial work is beginning to test the role of various mammalian and avian hosts in infecting feeding larval ticks with the pathogens of these two emerging TBDs. Knowledge Gaps and Research Opportunities Ostfeld identified a number of key questions that remain for future study: • Which factors other than the size of forest fragments predict the abundance of ticks and the prevalence of Lyme disease?
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From page 22... ...
In other cases, such as opossums or gray squirrels, it is unknown whether low reservoir competence is a function of that complement system, which is innate or of induced immunity, including antibody production. Environmental Factors Affecting Tick Populations One participant questioned the relationship between the population size of larval ticks and the opportunities for feeding on hosts.
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From page 23... ...
Land-Use and Public Health Strategy The relationship of tick and host habitat to the transmission of disease to humans was an area of considerable interest in which participants and Ostfeld discussed land-use strategies and the potential influence on public health. One participant asked whether there is an inherent geographic or landscape scale limit on the spread of Lyme disease.
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