Relapsing fever is caused by which genus of bacteria?

Relapsing fever is caused by which genus of bacteria?

• A. Borrelia
• B. Treponema
• C. Leptospira
• D. Spirillum

Answer: (A)

Relapsing fever is caused by bacteria of the genus Borrelia, a group of spirochetes known for their ability to shift surface proteins and evade the host immune response. This antigenic variation leads to recurrent fever spikes as the immune system clears one variant, only for a new variant to appear and repeat the febrile cycle. There are two main transmission forms: louse-borne relapsing fever from Borrelia recurrentis and tick-borne forms from other Borrelia species such as B. hermsii and B. turicatae. This genus distinction sets it apart from the other options: Treponema includes species that cause syphilis, Leptospira causes leptospirosis, and Spirillum is not associated with relapsing fever. The hallmark feature is the Borrelia genus with antigenic variation driving relapses.

Relapsing fever is caused by bacteria of the genus Borrelia, a group of spirochetes known for their ability to shift surface proteins and evade the host immune response. This antigenic variation leads to recurrent fever spikes as the immune system clears one variant, only for a new variant to appear and repeat the febrile cycle. There are two main transmission forms: louse-borne relapsing fever from Borrelia recurrentis and tick-borne forms from other Borrelia species such as B. hermsii and B. turicatae. This genus distinction sets it apart from the other options: Treponema includes species that cause syphilis, Leptospira causes leptospirosis, and Spirillum is not associated with relapsing fever. The hallmark feature is the Borrelia genus with antigenic variation driving relapses.