Question

Disease caused by one of the smallest known viruses
(a) Mumps
(b) Measles
(c) Poliomyelitis
(d) Trachoma

Answer 1

This virus belongs to the family picornaviridae with a diameter measuring about 30nm. It is a non-enveloped virus that attacks the central nervous system.

Complete step by step answer:
The smallest animal virus belongs to the family parvoviridae and picornaviridae. The virus in Parvoviridae measures about 20nm and picornaviridae measure 30nm in diameter. Poliomyelitis is a virus that belongs to the family picornaviridae.
- Mumps is a viral disease caused by the 'mumps virus' that belongs to the family paramyxoviridae. It measures around 150nm in diameter. They are enveloped spherically or pleomorphic. Symptoms of mumps often include fever, muscle pain, headache, swelling of parotid glands
- Measles is also a viral disease caused by the 'measles virus' belonging to the family paramyxoviridae. This virus causes temporary but severe immunosuppression. It measures around $100 \ nm$ to $300 \ nm$ in diameter. Symptoms often include fever, runny nose, inflamed eyes, koplik's spots.
- In $70\%$ of cases there are no symptoms for polio. It is of two types of minor illness and major illness. In minor illness, there is no involvement of the central nervous system. Major illness is further divided into paralytic and non-paralytic. In non-paralytic polio, upper respiratory tract infections, constipation, influenza-like symptoms are seen. In paralytic polio, there is the involvement of the central nervous system, which affects motor neurons which cause partial paralysis or complete paralysis of an organ.
- Trachoma is a bacterial infection caused by 'Chlamydia trachomatis' that belongs to the family Chlamydiaceae. It measures about 0.25 to 0.3 micrometers.
So, the correct answer is 'Poliomyelitis'.

Note:
- Poliomyelitis is cured by the polio vaccine.
- Some of the examples of viruses belong to picornaviridae are enterovirus, herpes simplex virus, cardiovirus A, etc.