Alpha viruses

Alpha viruses overview and Definition

Alpha viruses RNA enveloped virus belonging to Toga viridae family.They are mostly mosquitoe borne.The virus mainly affects the brain.Types of the Virus include. 1) eastern equine encephalomyelitis (EEE); 2) Venezuelan equine encephalomyelitis (VEE); and 3) western equine encephalomyelitis (WEE).They are atypical arboviruses and the pathogens include Chikunkunya and other encephalitis causing virus

Structure of Alpha viruses

Alpha viruses small ,single stranded ,enveloped virus.There are two frames in the genome which are termed as Structural Proteins and Non Structural proteins.The non structure proteins aid the virus in the transcription and replication of the viral DNA.The structural protein helps the virus to build the framework such as Core,nucleocapsid and plays a vital role in the receptor recognization and helps the virus to bind with the host.



Routes of Transmission

They are zoonotic pathogens and spreads from animals and birds to human and mosquitos acts as an vector.

Clinical signs & symptoms

The symptoms of the alpha virus include rash,arthralgia and fever. The Incubation period of the virus include 2-10 days. In the early phase, fever, muscle pains, malaise and headache are present. In the long run this can leads to petechiae,purpura,haemetemesis(vomiting of blood),melaena(blood in stools) and  bleeding gums.The joints affected commonly are ankle, wrist and phalanges. The symptoms are similar to other inflammatory joint diseases and it is difficult to differentiate clinically without further investigation.

Differential Diagnosis

Detection of virus-neutralizing antibodies in combination with recent travel history to an endemic area may be meaningful.

Immunosorbent assay- detect the virus specific IgM or IgG antibodies.

Greater than fourfold rise in titer between acute and convalescent sera  and  cerebo spinal fluid containing virus specific IgG or IgM or both are the diagnostic features.

Real Time Polymerase Chain Reaction (RT-PCR)- is valuable in the early confirmation of arbovirus infections, particularly chikungunya. However, the value of RT PCR is limited to diagnosis in the viraemic phase, with later infection requiring serology.

Direct immunofluorescnce assay-to detect chikungunya IgM has a high sensitivity and specificity and is used in the latter stages.However, the use of these tests in the tropics may be limited by financial constraints.

A normal erythrocyte sedimentation rate- and a negative rheumatoid factor are useful to differentiate chikungunya arthritis from rheumatoid arthiritis. Extensive, symmetrical joint involvement, particularly of the metacarpophalangeal and proximal joints, the presence of rheumatoid nodules or anti-cyclic citrullinated peptide (anti-CCP) antibodies favours rheumatoid arthritis over chikungunya with chronic arthropathy. The presence of lower limb asymmetrical joint involvement with axial skeletal affliction favours the diagnosis of spondyloarthropathy over chikungunya.


Use sterilized instruments. and household things

Clean the pets properly

Use mosquito repllents