Once Infected with Borrelia Recurrentis, a 2- to 15-Day Incubation

Once infected with Borrelia recurrentis, a 2- to 15-day incubation period follows where high numbers of organisms are found in the blood. The infected individual experiences high fever, rigors, severe headache, muscle pains, and weakness. This febrile period lasts for about 3 to 7 days, but ends quickly with the induction of an immune response. However, a similar but less severe course of symptoms recurs several days to weeks later. What causes this relapse?

A) The organism systematically changes its surface antigens during the course of a single infection.
B) The organism produces extracellular toxins that cause the symptoms.
C) This organism survives inside infected cells and once the cell dies, the organism is released into the blood, causing this relapse.
D) This relapse occurs as the host is trying to mount the secondary antibody response.