What vector is primarily responsible for transmitting Bartonella quintana in homeless populations?

Bartonella quintana is known as the causative agent of trench fever, and it is primarily transmitted through body lice. In homeless populations, where hygiene may be limited and close contact occurs, body lice infestations are common. The lice can carry the bacteria and transmit it when they bite a host, leading to infection. This mode of transmission is particularly significant in populations that may experience overcrowding and insufficient access to sanitary conditions, making lice a vector of concern.

Fleas, ticks, and mosquitoes are important vectors for other diseases but are not primarily responsible for the transmission of Bartonella quintana. Each of these vectors has specific disease associations that do not include trench fever, highlighting why understanding the specific vectors linked to particular infections is critical in public health contexts.