5-42. RUSSIAN SPRING-SUMMER ENCEPHALITIS
This disease belongs to the group of viral encephalitides previously
a. Transmission. Epidemiologically, it differs from them in that
it is transmitted by a hard tick (genus Ixodes) rather than a mosquito. Humans are
infected accidentally in the rodent-tick-rodent cycle of infection.
The tick, which apparently is the true reservoir, remains infective for life
and passes the virus to progeny by transovarian passage.
The disease is widespread throughout much of Eastern Europe and
One attack confers immunity.
b. Transmission/Prevention. There is no specific treatment. Prevention is the
same as for other tick-borne diseases.
5-43. COLORADO TICK FEVER
Colorado tick fever is an acute febrile, tick-borne viral disease similar to
dengue. It is usually a mild disease, deaths being uncommon. It is found
throughout the western U.S., especially at high altitudes.
a. Reservoir/Vector. Small mammals, particular ground squirrels, chipmunks,
and porcupines, serve as the reservoir, and it is vectored by the wood tick (Dermacentor
andersoni), a hard tick.
b. Treatment/Prevention. There is no specific treatment or immunization for
the disease. Prevention is the same as for other tick-borne diseases.
5-44. TICK-BORNE VIRAL HEMORRHAGIC FEVERS
Several viral hemorrhagic fevers are transmitted by means of tick vectors.
a. Signs/Symptoms. The hemorrhagic fevers are characterized
Severe pain in the limbs and lower back.
Sometimes--vomiting, abdominal pain, and diarrhea.