25.2 Bacterial infections of the circulatory and lymphatic systems  (Page 17/24)

The symptoms of Lyme disease follow three stages: early localized, early disseminated, and late stage. During the early-localized stage, approximately 70%–80% Centers for Disease Control and Prevention. “Signs and Symptoms of Untreated Lyme Disease.” 2015. http://www.cdc.gov/lyme/signs_symptoms/index.html. Accessed July 27, 2016. of cases may be characterized by a bull's-eye rash, called erythema migrans, at the site of the initial tick bite. The rash forms 3 to 30 days after the tick bite (7 days is the average) and may also be warm to the touch ( [link] ). Centers for Disease Control and Prevention. “Ticks. Symptoms of Tickborne Illness.” 2015. http://www.cdc.gov/ticks/symptoms.html. Accessed July 27, 2016. This diagnostic sign is often overlooked if the tick bite occurs on the scalp or another less visible location. Other early symptoms include flu-like symptoms such as malaise, headache, fever, and muscle stiffness. If the patient goes untreated, the second early-disseminated stage of the disease occurs days to weeks later. The symptoms at this stage may include severe headache, neck stiffness, facial paralysis, arthritis, and carditis. The late-stage manifestations of the disease may occur years after exposure. Chronic inflammation causes damage that can eventually cause severe arthritis, meningitis, encephalitis, and altered mental states. The disease may be fatal if untreated.

A presumptive diagnosis of Lyme disease can be made based solely on the presence of a bull’s-eye rash at the site of infection, if it is present, in addition to other associated symptoms ( [link] ). In addition, indirect immunofluorescent antibody (IFA) labeling can be used to visualize bacteria from blood or skin biopsy specimens. Serological tests like ELISA can also be used to detect serum antibodies produced in response to infection. During the early stage of infection (about 30 days), antibacterial drugs such as amoxicillin and doxycycline are effective. In the later stages, penicillin G , chloramphenicol , or ceftriaxone can be given intravenously.

Relapsing fever

Borrelia spp. also can cause relapsing fever . Two of the most common species are B. recurrentis , which causes epidemics of louseborne relapsing fever, and B. hermsii , which causes tickborne relapsing fevers. These Borrelia species are transmitted by the body louse Pediculus humanus and the soft-bodied tick Ornithodoros hermsi , respectively. Lice acquire the spirochetes from human reservoirs, whereas ticks acquire them from rodent reservoirs. Spirochetes infect humans when Borrelia in the vector’s saliva or excreta enter the skin rapidly as the vector bites.