This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
A 15-year-old boy is bitten by an Ixodes tick while camping with his parents and presents 1 week later with fatigue, fever, headache, and a reddish rash over his trunk and extremities. Positive IgM antibody (1 :200) to Borrelia burgdorferi is associated with which of the following? 
Select and explain. 
A. Acute Lyme disease, B. Fifth disease, C. Possible hepatitis B infection, D. Possible subacute sclerosing panencephalitis (SSPE)
A: Acute Lyme disease
Answer: A: Acute Lyme disease 
Explanation: Borrelia burgdorferi, the causative agent of Lyme disease, elicits an acute antibody response. IgM appears within days to a few weeks following tick bite, and IgG appears a few weeks later. IgG persists; IgM does not. Cross-reactions occur with other treponemes.