A biphasic fever is more often seen in children compared to adults. The first fever arrives with the onset of general constitutional symptoms, and the second accompanying the onset of the neurological symptoms.Symptoms can vary depending on the virus responsible for infection. Enteroviral meningitis (the most common cause) typically presents with the classic headache, photophobia, fever, nausea, vomiting, and nuchal rigidity. With coxsackie and echo virus specifically, a maculopapular rash may be present, or even the typical vesicles seen with Herpangina. Lymphocytic choriomeningitis virus (LCMV) can be differentiated from the common presenting meningeal symptoms by the appearance of a prodromal influenza-like sickness about 10 days before other symptoms begin. Mumps meningitis can present similarly to isolated mumps, with possible parotid and testicular swelling. Interestingly, research has shown that HSV-2 meningitis most often occurs in people with no history of genital herpes, and that a severe frontal headache is among the most common presenting symptoms. Patients with varicella zoster meningitis may present with herpes zoster (Shingles) in conjunction with classic meningeal signs. Meningitis can be an indication that an individual with HIV is undergoing seroconversion, the time when the human body is forming antibodies in response to the virus. Causes
The most common causes of viral meningitis in the United States are non-polio enteroviruses. The viruses that cause meningitis are typically acquired from sick contacts.
However, in most cases, people infected with viruses that may cause meningitis do not actually develop meningitis.Viruses that can cause meningitis include:

Mechanism
Viral Meningitis is mostly caused by an infectious agent that has colonized somewhere in its host. People who are already in an immunocompromised state are at the highest risk of pathogen entry. Some of the most common examples of immunocompromised individuals include those with HIV, cancer, diabetes, malnutrition, certain genetic disorders, and patients on chemotherapy. Potential sites for this include the skin, respiratory tract, gastrointestinal tract, nasopharynx, and genitourinary tract. The organism invades the submucosa at these sites by invading host defenses, such as local immunity, physical barriers, and phagocytes or macrophages. After pathogen invasion, the immune system is activated. An infectious agent can enter the central nervous system and cause meningeal disease via invading the bloodstream, a retrograde neuronal pathway, or by direct contiguous spread. Immune cells and damaged endothelial cells release matrix metalloproteinases (MMPs), cytokines, and nitric oxide. MMPs and NO induce vasodilation in the cerebral vasculature. Cytokines induce capillary wall changes in the blood brain barrier, which leads to expression of more leukocyte receptors, thus increasing white blood cell binding and extravasation.The barrier that the meninges create between the brain and the bloodstream are what normally protect the brain from the bodys immune system. Damage to the meninges and endothelial cells increases cytotoxic reactive oxygen species production, which damages pathogens as well as nearby cells.