Epidemic typhus, also known as louse-borne typhus, is a form of typhus so named because the disease often causes epidemics following wars and natural disasters where civil life is disrupted. Epidemic typhus is spread to people through contact with infected body lice, in contrast to endemic typhus which is usually transmitted by fleas.Though typhus has been responsible for millions of deaths throughout history, it is still considered a rare disease that occurs mainly in populations that suffer unhygienic extreme overcrowding. Typhus is most rare in industrialized countries. It occurs primarily in the colder, mountainous regions of central and east Africa, as well as Central and South America. The causative organism is Rickettsia prowazekii, transmitted by the human body louse (Pediculus humanus corporis). Untreated typhus cases have a fatality rate of approximately 40%.Epidemic typhus should not be confused with Murine typhus, which is more endemic to the United States, particularly Southern California and Texas. This form of typhus has similar symptoms, but is caused by Rickettsia typhi. It is carried primarily in rat feces and fleas, as well as other rodents. It is not as deadly as louse-born typhus. It occurs only during the summer and fall, when rodents are active among humans. Signs and symptoms
Symptoms of this disease typically begin within 2 weeks of contact with the causative organism.
Bacteria
Lyme disease
Syphilis
Leptospirosis
Fungi
Cryptococcal infection
Coccidioidal infection
Drug-induced aseptic meningitis (DIAM)
Irritation of the meninges from drugs administered directly to the spinal canal or subarachnoid space. The hypersensitivity to the drug results in an immune response. Autoimmune diseases
Systemic lupus erythematosus. Cancer-caused aseptic meningitis such as neoplastic meningitis
This affects about 5% of all cancer cases, with a predominance in leukemias. Neurosarcoidosis

Diagnosis
The term aseptic can be misleading, implying a lack of infection. On the contrary, many cases of aseptic meningitis represent infection with viruses or mycobacteria that cannot be detected with routine methods. Medical professionals will take into consideration the season of the year, the medical history of the individual and family, physical examination, and laboratory results when diagnosing aseptic meningitis.One common medical test used when diagnosing aseptic meningitis is lumbar puncture. A medical professional inserts a needle between two vertebrae to remove cerebrospinal fluid (CSF) from the spinal cord. The cerebrospinal fluid collected from the lumbar puncture is analyzed by microscope examination or by culture to distinguish between bacterial and aseptic meningitis. Samples of CSF undergo cell count, Gram stains, and viral cultures, and polymerase chain reaction (PCR). Polymerase chain reaction has increased the ability of clinicians to detect viruses such as enterovirus, cytomegalovirus, and herpes virus in the CSF, but many viruses can still escape detection. Other laboratory tests include blood, urine, and stool collection. Medical professionals also have the option of performing a computed tomographic (CT) scan or magnetic resonance imaging (MRI), these tests help observe calcifications or abscesses.