Viruses causing hemorrhagic fever are-

Ans. is 'a' i.e., Lassa fever virus Clinical classification of arboviruses . On the basis of usual clinical picture described, three clinical syndromes have been described which can be caused by arboviruses Febrile group (fever and myalgia) - This is the most common group which comprises a large number of undifferentiated fevers, generally begin with or without rashes and joint pain. - Impoant viruses in this group are :- Dengue, Chikungunya, West Nile, Colorado tickfever, Sandfly fever and Sindbis. ii) Encephilitis group - This group affects CNS and causes encephalitis or meningoencephalitis. - Impoant virus in this group are :- California serogroup viruses (California encephalitis, Jamestown canyon, Kesstone, La Cross,Trivittatus), St Louis, JE, central European, Russian spring summer, West Nile, Powassan, Eastern Equine, Western Equine and Venezuela. iii) Hemorrhagic group - Hemorrhagic group is associated with hemorrhage. - Impoant viruses in this group are :- Dengue, KFD, Chikungunya, Yellow fever, Lassa, Crimean HE Congo, Omek, Rift valley, Hanta virus, Marbung or Ebola. . These ( above described) categories are somewhat arbitrary and some arboviruses may be associated with more than one syndrome.eg. Dengue virus can cause all three clinical syndromes.