Gram Negative Spiral
Borrelia burgdorferi, the causative agent of Lyme disease, has been isolated from a variety of ticks such as Ixodes scapularis, Amblyomma, Dermacentor, and Ixodes pacificus. Which one of the following statements is true of Lyme disease.
|A||Dermacentor and Amblyomma are significant vectors of B. burgdorferi to humans.|
|B||Dogs and cats are naturally immune to Lyme disease|
|C||I. scapularis and Ixodes dammini are different types of ticks|
|D||Only a small percentage of people who get bitten by a tick develop Lyme disease.|
a. Burgdorferi, the causative agent of Lyme disease, has two principal vectors: I. scapularis in the eastern and Midwestern United States and I. pacificus in the western United States. The ticks are tiny and can easily be missed. Fortunately, relatively few people who are bitten by ticks develop Lyme disease.
b. Lyme disease, usually with joint involvement, is also seen in veterinary patients such as dogs, cats, and horses. White-tailed deer and small rodents are an important reservoir for these ticks.
c. Burgdorferi has been isolated from mosquitoes and Dermacentor and Amblyomma ticks as well as from several Ixodes species. However, the isolation of the bacterium from these ticks is not sufficient evidence to indicate that they transmit the disease to humans.
a. Characterized by recurrent acute episodes of fever followed by nonfebrile periods of increasing duration.
b. Spread by two distinct vector families, namely the human body louse and ticks, and is caused by various species of Borrelia.
c. The human body louse spreads Borrelia recurrentis infection.
d. Tick-borne relapsing fever can be caused by a least 15 different Borrelia species. As mentioned above, Louse-borne relapsing fever is caused only by Borrelia recurrentis.
e. Borrelia turicatae, Borrelia hermsii, Borrelia parkeri, and Borrelia duttonii may cause the tick-borne relapsing fever.
f. Louse-borne and tick-borne relapsing fevers differ in their epidemiology and must be considered separately.
g. The human body louse transmits an epidemic form and is always associated with B recurrentis, whereas tick transmits the endemic relapsing fever and may be caused by several different Borrelia species.
h. Humans are the only host for louse-borne relapsing fever, whereas small mammals and lizards may serve as the natural reservoir for tick-borne Borrelia species.