Patients infected in solid organ transplants have developed a severe fatal illness, starting within weeks of the transplant. In all reported cases, the initial symptoms included fever, lethargy, anorexia and leukopenia, and quickly progressed to multisystem organ failure, hepatic insufficiency or severe hepatitis, dysfunction of the transplanted organ, coagulopathy, hypoxia, multiple bacteremias and shock. Localized rash and diarrhea were also seen in some patients. Nearly all cases have been fatal.

In May 2005, four solid-organ transplant recipients contracted an illness that was later diagnosed as lymphocytic choriomeningitis. All received organs from a common donor, and within a month of transplantation, three of the four recipients had died as a result of the viral infection. Epidemiologic investigation traced the source to a pet hamster that the organ donor had recently purchased from a Rhode Island pet store. Similar cases occurred in Massachusetts in 2008, and Australia in 2013. Currently, there is not a LCMV infection test that is approved by the Food and Drug Administration for organ donor screening. The "Morbidity and Mortality Weekly Report" advises health-care providers to "consider LCMV infection in patients with aseptic meningitis and encephalitis and in organ transplant recipients with unexplained fever, hepatitis, or multisystem organ failure."

Lymphocytic choriomeningitis is not a commonly reported infection in humans, though most infections are mild and are often never diagnosed. Serological surveys suggest that approximately 1–5% of the population in the U.S. and Europe has antibodies to LCMV. The prevalence varies with the living conditions and exposure to mice, and it has been higher in the past due to lower standards of living. The island of Vir in Croatia is one of the biggest described endemic places of origin of LCMV in the world, with IFA testing having found LCMV antibodies in 36% of the population. Individuals with the highest risk of infection are laboratory personnel who handle rodents or infected cells. Temperature and time of year is also a critical factor that contributes to the number of LCMV infections, particularly during fall and winter when mice tend to move indoors. Approximately 10–20% of the cases in immunocompetent individuals are thought to progress to neurological disease, mainly as aseptic meningitis. The overall case fatality rate is less than 1% and people with complications, including meningitis, almost always recover completely. Rare cases of meningoencephalitis have also been reported. More severe disease is likely to occur in people who are immunosuppressed.

More than 50 infants with congenital LCMV infection have been reported worldwide. The probability that a woman will become infected after being exposed to rodents, the frequency with which LCMV crosses the placenta, and the likelihood of clinical signs among these infants are still poorly understood. In one study, antibodies to LCMV were detected in 0.8% of normal infants, 2.7% of infants with neurological signs and 30% of infants with hydrocephalus. In Argentina, no congenital LCMV infections were reported among 288 healthy mothers and their infants. However, one study found that two of 95 children in a home for people with severe mental disabilities had been infected with this virus. The prognosis for severely affected infants appears to be poor. In one series, 35% of infants diagnosed with congenital infections had died by the age of 21 months.

Transplant-acquired lymphocytic choriomeningitis proves to have a very high morbidity and mortality rate. In the three clusters reported in the U.S. from 2005 to 2010, nine of the ten infected recipients died. One donor had been infected from a recently acquired pet hamster while the sources of the virus in the other cases were unknown.

The U.S. Centers for Disease Control and Prevention (CDC) publishes a journal "Emerging Infectious Diseases" that identifies the following factors contributing to disease emergence:

- Microbial adaption; e.g. genetic drift and genetic shift in Influenza A

- Changing human susceptibility; e.g. mass immunocompromisation with HIV/AIDS

- Climate and weather; e.g. diseases with zoonotic vectors such as West Nile Disease (transmitted by mosquitoes) are moving further from the tropics as the climate warms

- Change in human demographics and trade; e.g. rapid travel enabled SARS to rapidly propagate around the globe

- Economic development; e.g. use of antibiotics to increase meat yield of farmed cows leads to antibiotic resistance

- Breakdown of public health; e.g. the current situation in Zimbabwe

- Poverty and social inequality; e.g. tuberculosis is primarily a problem in low-income areas

- War and famine

- Bioterrorism; e.g. 2001 Anthrax attacks

- Dam and irrigation system construction; e.g. malaria and other mosquito borne diseases

An emerging infectious disease (EID) is an infectious disease whose incidence has increased in the past 20 years and could increase in the near future. Emerging infections account for at least 12% of all human pathogens. EIDs are caused by newly identified species or strains (e.g. Severe acute respiratory syndrome, HIV/AIDS) that may have evolved from a known infection (e.g. influenza) or spread to a new population (e.g. West Nile fever) or to an area undergoing ecologic transformation (e.g. Lyme disease), or be "reemerging" infections, like drug resistant tuberculosis. Nosocomial (hospital-acquired) infections, such as methicillin-resistant Staphylococcus aureus are emerging in hospitals, and extremely problematic in that they are resistant to many antibiotics. Of growing concern are adverse synergistic interactions between emerging diseases and other infectious and non-infectious conditions leading to the development of novel syndemics. Many emerging diseases are zoonotic - an animal reservoir incubates the organism, with only occasional transmission into human populations.

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:

It has been proposed that viral meningitis might lead to inflammatory injury of the vertebral artery wall.

The Meningitis Research Foundation is conducting a study to see if new genomic techniques can the speed, accuracy and cost of diagnosing meningitis in children in the UK. The research team will develop a new method to be used for the diagnosis of meningitis, analysing the genetic material of microorganisms found in CSF (cerebrospinal fluid). The new method will first be developed using CSF samples where the microorganism is known, but then will be applied to CSF samples where the microorganism is unknown (estimated at around 40%) to try and identify a cause.