Bartonella quintana is a type of bacteria that primarily infects humans and is known to cause trench fever. This disease was historically associated with soldiers during World War I, who often lived in unsanitary conditions. The bacteria are transmitted mainly through body lice, making poor hygiene a significant risk factor for infection. In addition to trench fever, Bartonella quintana can lead to other health issues, such as endocarditis and bacteremia. Symptoms of trench fever include fever, headache, and muscle pain, which can recur over time. Treatment typically involves antibiotics to eliminate the infection.