Trench fever is caused by the Gram-negative bacterium, Bartonella quintana. The disease is spread by the human louse and is characterized by sudden onset of fever, headaches, myalgias, shin pain, arthralgia, and cutaneous lesions on the chest and back. A high incidence of the illness was reported during the two world wars and is now reported amongst those living in unhygienic conditions or extreme poverty.
Symptoms of trench fever or quintan fever typically appear between 3 to 45 days after contact with the human louse which is the vector transmitting the causative bacteria, Bartonella quintana. The disease has been reported amongst individuals living in unhygienic conditions, such as homeless, in both developing and developed countries .
The fever is accompanied by frontal or retro-orbital headaches with meningismus, photophobia, weakness, depression, restlessness, insomnia, shin and loin pain radiating to the upper back or lower extremities, dyspnea, conjunctivitis, and an erythematous, macular rash on the chest and back. Other symptoms like anorexia, nausea vomiting, diarrhea, or constipation may also be present. Although urban trench fever includes one or more of the above manifestations, its presentation tends to be more variable with abdominal and neurologic symptoms being uncommon      .
Certain syndromes are now known to be associated with Bartonella quintana infection. They may be asymptomatic and may have negative blood cultures. Their clinical features are:
The diagnosis of trench fever should be suspected in individuals with poor personal hygiene and poor immunity. Classical symptoms may raise the suspicion of the disease but in atypical cases diagnosis can be challenging. Laboratory diagnosis of trench fever can be unequivocal. Bartonella quintana can be isolated by subculturing the blood culture broth although results may be available from anywhere between 14 to 45 days . Cross-reactivity with other organisms is the cause of poor specificity of serological tests. In addition, the poor immune response in immunocompromised patients can interfere with tests. Immunofluorescent assays (IFAs) can be confirmatory in acute cases as well as convalescing patients.
Enzyme immunoassay (EIA) and enzyme-linked immunosorbent assay (ELISA) techniques are helpful in detection of antibodies  . Endocarditis is associated with the highest levels of antibodies . Polymerase chain reaction (PCR) assays and histochemical stains can detect Bartonella quintana DNA and are very specific if the results are positive . Bartonella quintana DNA can be detected in vegetations obtained from cases of endocarditis as well as in skin samples if cutaneous lesions of bacillary angiomatosis are suspected  .