Which statement best describes the three clinical outcomes of poliovirus infection?

• A. Mild gastroenteritis, severe gastroenteritis, dehydration
• B. Clinically inapparent, non-paralytic poliomyelitis, and paralytic poliomyelitis
• C. Asymptomatic carriage, chronic fatigue, pneumonia
• D. Meningitis, encephalitis, seizures

Answer: (B)

Poliovirus has a spectrum of illness that ranges from no symptoms to CNS involvement and paralysis. The key idea is that infection can be clinically inapparent, can cause non-paralytic poliomyelitis (inflammatory illness of the meninges without paralysis), or can cause paralytic poliomyelitis (acute flaccid paralysis due to motor neuron damage).

Clinically inapparent infection means the person has no noticeable illness, yet the virus replicates and can be shed, contributing to transmission and immunity. Non-paralytic poliomyelitis presents with signs of meningitis (fever, headache, neck stiffness) but without paralysis. Paralytic poliomyelitis involves destruction of motor neurons, leading to rapid-onset, asymmetric flaccid paralysis and possible respiratory failure; this form can be severe and sometimes fatal.

The option that lists clinically inapparent, non-paralytic poliomyelitis, and paralytic poliomyelitis best describes this complete clinical spectrum. Other choices mix in conditions like gastroenteritis, pneumonia, or seizures that are not the defining outcomes of poliovirus infection.