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Japanese Encephalitis Virus is a virus from the family Flaviviridae, that causes inflammation of the membranes around the brain. Japanese encephalitis is spread by infected mosquitoes, Culex tritaeniorhynchus and Culex vishnui groups. It is spread throughout eastern Asia, including India, Japan, China and southeast Asia.
Most Japanese encephalitis virus infections are mild (fever and headache) or without apparent symptoms, but approximately 1 in 200 infections results in severe disease characterized by rapid onset of high fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis and death. The case fatality rate can be as high as 60% among those with disease symptoms; 30% of those who survive suffer from lasting damage to the central nervous system. However, there is no specific treatment for Japanese encephalitis.
 Legionella is a group of bacteria which belong to the family Legionellaceae, with at least 50 species and 70 serogroups identified. Among these species, approximately 90% of infections are caused by L. pneumophila, serogroup 1; and this species is accountable for the Legionnaires' disease which is a lung infection.
Patients who have contracted Legionnaires' disease may feel tired and weak. Most patients who are admitted to the hospital develop high fever often greater than 39.5°C. Cough can be the first sign of a lung infection. The cough may be sufficiently severe to cause sputum production. Gastrointestinal stomach symptoms are common with diarrhea being the most distinctive symptom. Many patients have nausea, vomiting, and stomach discomfort. Other common symptoms include headaches, muscle aches, chest pain, and shortness of breath.
The major source is water distribution systems of large buildings including hotels and hospitals. Cooling towers are also a major source for Legionella. Other sources include mist machines, humidifiers, whirlpool spas, and hot springs. Hospital-acquired Legionella pneumonia has a fatality rate of 28%.
 Noroviruses of genus Norovirus and family Caliciviridae are a group of related, single-stranded RNA, non-enveloped viruses that cause acute gastroenteritis in humans. The most common symptoms of acute gastroenteritis are diarrhea, vomiting, and stomach pain.
Noroviruses spread from person to person, through contaminated food or water, and by touching contaminated surfaces. They are found in the stool and vomit of infected people. Norovirus is recognized as one of the leading causes of foodborne-disease outbreaks, given the ease of transmission and its highly contagious nature of the virus.
Because the above three illnesses are not caused by bacteria, antibiotics do not help treat the infections.
 Respiratory Syncytial Virus (RSV) , is a respiratory virus that infects the lungs and respiratory tract. It is the leading cause of lower respiratory tract infection in infants and young children - virtually all children have had at least one RSV infection by their third birthday. In adults and older, healthy children, the symptoms of respiratory syncytial virus are mild and typically mimic the common cold. Most otherwise healthy people recover from RSV infection in 1 to 2 weeks. However, RSV can also become serious in premature babies and infants with underlying health conditions; older adults and adults with heart and lung diseases.
RSV spreads easily by direct contact, and can remain viable for a half an hour or more on hands or for up to 5 hours on countertops. There is prophylactic medication (not a vaccine), but at present no vaccine exists.
 West Nile Virus (WNV) is also a virus of the family Flaviviridae. It is commonly found in both tropical and temperate regions. The main route of human infection is through the bite of an infected mosquito, which species vary according to geographical area: in the US Culex pipiens (Eastern US), Culex tarsalis (Midwest and West), and Culex quinquefasciatus (Southeast) are the main sources.
Approximately 80% of people who are infected with WNV will not show any symptoms at all. Up to 20% of the people who become infected have symptoms such as fever, headache, and body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. About one in 150 people infected with WNV will develop severe illness, including high fever, headache, neck stiffness, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis.
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