Picornaviruses are small, nonenveloped, single-stranded RNA viruses that include enteroviruses, rhinoviruses, and hepatovirus, which affect humans. Enteroviruses can cause various diseases, from respiratory infections to poliomyelitis, while hepatitis A virus leads to acute liver disease. Prevention and control of these infections rely on public education, good hygiene practices, and vaccines such as the oral polio vaccine and hepatitis A vaccine.

1. Picornavirus
A virus belonging to the family
Picornaviridae, a family of viruses in
the order Picornavirales
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2. Introduction
• The picornaviruses are small (22 to 30 nm) nonenveloped, single-stranded RNA viruses with cubic
symmetry
• The virus capsid is composed of 60 protein subunits, each consisting of four poly-peptides VP1–VP4
• Because they contain no essential lipids, they are ether resistant
• They replicate in the cytoplasm
• The picornaviruses that affect humans are
• The enteroviruses, found primarily in the gut
• the rhinoviruses, found in the upper respiratory tract
• hepatovirus (Hepatitis A virus) in the intestine and liver.

3. Introduction

4. Classification
The family Picornaviridae comprises five genera:
• Enterovirus
• Hepatovirus
• Rhinovirus, which infect humans
• Apthovirus (foot-and-mouth disease virus), which infects cloven-hoofed animals and occasionally humans;
• Cardiovirus, which infects rodents

5. Classification

6. Clinical Manifestation : Enteroviruses
• Enteroviruses are stable under acid conditions and thus they are able to survive exposure to gastric acid
• Enteroviruses are implicated in many diseases, including:
1. undifferentiated febrile illnesses (fever with uncertain cause)
2. upper and lower respiratory tract infections
3. gastrointestinal disturbances
4. Conjunctivitis
5. skin and mucous membrane lesions
6. diseases of the central nervous system, muscles, heart, and liver

7. Clinical Manifestation : Enteroviruses
Less commonly, enteroviruses are associated with
1. generalized neonatal infections
2. diabetes mellitus
3. Pancreatitis (inflammation of pancreas)
4. Orchitis (inflammation of the testicles)
5. occasionally hemolytic-uremic syndrome (a condition that affects the blood and blood vessels. It results
in the destruction of blood platelets (cells involved in clotting), a low red blood cell count (anemia) and
kidney failure due to damage to the very small blood vessels of the kidneys)
6. intrauterine infections (infection within the womb)

8. • Polio, also called poliomyelitis or infantile paralysis, is an infectious disease caused by the poliovirus
• there is muscle weakness resulting in an inability to move. This can occur over a few hours to a few days
• The weakness most often involves the legs but may less commonly involve the muscles of the head, neck
and diaphragm
• In up to 70 percent of infections there are no symptoms
• Years after recovery post-polio syndrome may occur, with a slow development of muscle weakness
similar to that which the person had during the initial infection
• Poliovirus is usually spread from person to person through infected fecal matter entering the mouth
Poliomyelitis

9. Symptoms include:
• Fever, Sore throat, Headache, Vomiting and Fatigue
• Back pain or stiffness, Neck pain or stiffness, Pain or stiffness in the arms or legs
• Muscle weakness or tenderness
• Loss of reflexes
• Severe muscle aches or weakness
• Loose and floppy limbs (flaccid paralysis)
Poliomyelitis

10. Prevention
• Two types of vaccine are used throughout the world to combat polio
• Both types induce immunity to polio, efficiently blocking person-to-person transmission of wild poliovirus,
thereby protecting both individual vaccine recipients and the wider community
• The first candidate polio vaccine, based on one serotype of a live but attenuated (weakened) virus, was
developed by the virologist Hilary Koprowski.
• The second inactivated polio virus vaccine was developed in 1952 by Jonas Salk
• The Salk vaccine, or inactivated poliovirus vaccine, is based on poliovirus grown in a type of monkey kidney
tissue culture (vero cell line), which is chemically inactivated with formalin
Poliomyelitis

11. Prevention
• Albert Sabin developed another live, oral polio vaccine (OPV)
• It was produced by the repeated passage of the virus through nonhuman cells at subphysiological
temperatures.
• The attenuated poliovirus in the Sabin vaccine replicates very efficiently in the gut, the primary site of wild
poliovirus infection and replication, but the vaccine strain is unable to replicate efficiently within nervous
system tissue
• Because the oral polio vaccine is inexpensive, easy to administer, and produces excellent immunity in the
intestine (which helps prevent infection with wild virus in areas where it is endemic), it has been the vaccine of
choice for controlling poliomyelitis in many countries
Poliomyelitis

12. The switch
• The Sabin oral poliovirus vaccine (OPV), which has been used globally by WHO in the
eradication effort, is a trivalent vaccine that contains all three serotypes.
• In September 2015 WHO declared that wild poliovirus type 2 has been eradicated from the
planet – no cases caused by this serotype had been detected since November 1999
• However, in 2015, there were 9 cases of poliomyelitis caused by the type 2 vaccine. For
these reasons WHO decided to remove the type 2 Sabin strain from OPV, and switch from
trivalent to bivalent vaccine in April 2016
• Removing the type 2 strain from OPV will eliminate vaccine-associated poliomyelitis in
recipients caused by this serotype
• To avoid such risk, developed countries like USA has already switched to IPV from OPV
Poliomyelitis

13. Treatment
• There is no cure for polio
• The focus of modern treatment has been on providing relief of symptoms, speeding recovery and preventing
complications
• Supportive measures include antibiotics to prevent infections in weakened muscles, analgesics for pain,
moderate exercise and a nutritious diet
• Portable ventilators may be required to support breathing
• Treatment of polio often requires long-term rehabilitation, including occupational therapy, physical therapy,
braces, corrective shoes
Poliomyelitis

14. • Coxsackievirus is a virus that belongs to a family of nonenveloped, linear,
positive-sense single-stranded RNA viruses
• Coxsackieviruses share many characteristics with poliovirus
• group A coxsackieviruses tend to infect the skin and mucous membranes,
causing herpangina; acute hemorrhagic conjunctivitis; and hand, foot, and
mouth (HFM) disease
• Picornaviruses, such as coxsackievirus A24 and enterovirus 70 cause acute
hemorrhagic conjunctivitis
Coxsackie Virus

15. • Hepatitis A virus (HAV), classified as hepatovirus, is a small, unenveloped symmetrical RNA virus which
shares many of the characteristics of the picornavirus family, and is the cause of infectious or epidemic
hepatitis transmitted by the fecal-oral route
• virus enters the body by ingestion and intestinal infection
• The virus then spreads, probably by the bloodstream, to the liver, a target organ
• Large numbers of virus particles are detectable in feces during the incubation period, beginning as early
as 10–14 days after exposure and continuing
• Antibody to hepatitis A virus that persists is also detectable late in the incubation period, coinciding
approximately with the onset of biochemical evidence of liver damage
Hepatitis A virus

16. • Fatigue
• Sudden nausea and vomiting
• Abdominal pain or discomfort, especially on the
upper right side beneath your lower ribs (by your
liver)
• Clay-colored bowel movements
• Loss of appetite
• Low-grade fever
• Dark urine
• Joint pain
• Yellowing of the skin and the whites of your eyes
(jaundice)
• Intense itching
Hepatitis A virus

17. • Unlike other types of viral hepatitis, hepatitis A does not cause long-term liver damage, and it doesn't
become chronic
• In rare cases, hepatitis A can cause a sudden loss of liver function, especially in older adults or people with
chronic liver diseases
• Acute liver failure requires a stay in the hospital for monitoring and treatment. Some people with acute
liver failure may need a liver transplant
• The hepatitis A vaccine can prevent infection with the virus
• The vaccine is typically given in two shots. The first one is followed by a booster shot six months later
Hepatitis A virus

18. • Enteroviruses and rhinoviruses may be isolated from feces pharyngeal swabs, saliva, and nasal aspirates, and
some enteroviruses may be isolated from skin lesions, conjunctiva cerebrospinal fluid, spinal cord, brain,
heart, and blood
• Virus is present in respiratory and conjunctival secretions from a few days before onset of illness to about 1
week after
• Virus excretion in feces may continue for several weeks or longer
Diagnosis

19. • Control of picornavirus diseases depends largely on mass education of the public on the mode of virus
transmission, stressing the importance of good personal hygiene, and on provision of a good sewage disposal
system and uncontaminated water supply
• Fecal and pharyngeal discharges are infectious; hence, they must be handled with care and disposed of safely
• Vaccine is commercially available for poliomyelitis and hepatitis A
• There is no established specific therapy
• Treatment is symptomatic and supportive
• Clinical studies show that ribavirin shortens respiratory illnesses and interferon nasal sprays have prophylactic
value for common colds
Control