<unk>  refers to instances where<unk>  occurs in an individual with no clear history of exposure to a<unk>  vector. Determining history of contact, usually via the bite of an infected animal, can be difficult if the patient is unconscious or incoherent by the time an attempt is made to collect patient history. Thus, friends and family are needed to fill in patient history of possible bite exposure. Additionally, bites from a vector can be overlooked, particularly for some small bat species. Bites from a bat can be so small that they are not visible without magnification equipment, for example. Outside of bites,<unk>  virus exposure can also occur if infected fluids come in contact with a mucous membrane or a break in the skin.<unk>  virus has also been transmitted when an infected human unknowingly dies of<unk> , and their organs are transplanted to others. While it has been speculated that<unk>  virus could be transmitted through aerosols, studies of the<unk>  virus have concluded that this is only feasible in limited conditions. These conditions include a very large colony of bats in a hot and humid cave with poor ventilation. While two human deaths in 1956 and 1959 had been tentatively attributed to aerosolization of the<unk>  virus after entering a cave with bats, "investigations of the 2 reported human cases revealed that both infections could be explained by means other than aerosol transmission".
Cryptic rabies
Brain fever
Tick-borne encephalitis
Eastern equine encephalitis
Tomato fever
Japanese encephalitis
Postvaccinal encephalitis
Saint Louis encephalitis