Enteric Infection Viruses

What are Enteric infection viruses?

Enteric infection virus is a virus that is transmitted mainly through the digestive tract. Many viruses can be infected through the digestive tract, with a focus on the enteroviruses of the picornaviridae family and related viruses that cause acute gastroenteritis.

Small RNA viruses include: polio virus, coxsackie virus and ECHO virus, new enterovirus.

Acute gastroenteritis viruses include: rotavirus, calicivirus and astrovirus, and enterovirus.

What is Small RNA virus?

The Picornaviridae family includes 4 genera, of which enterovirus and rhinovirus are most closely related to human diseases. This section focuses on enteroviruses.

        Enteroviruses are divided into 4 subgroups according to the host range and pathogenicity, namely polio virus, coxsackie virus, Echo virus (ECHO virus) and neo-enteric virus.

According to the neutralization test, it is divided into 1 to 72 serotypes, of which 72 is hepatitis A virus, which is now listed as hepatovirus.

1. Polio virus

        Poliovirus is a worldwide distribution. It is the pathogen that causes poliomyelitis. Most people are asymptomatic after being infected with poliovirus, and they are often subclinical.

Only about 0.1% of infected people invade the central nervous system, destroy motor neurons in the anterior horn of the spinal cord, and cause flaccid paralysis.

This disease is more common in children, so it is also called polio. 

The World Health Organization (WHO) has listed polio as the second infectious disease to be eliminated after smallpox, and polio has now been eliminated in most regions.

2. Coxsackie virus and ECHO virus

         Coxsackievirus is a subgroup of the enterovirus genus, with 30 serotypes. ECHO virus, also known as entero cytopathogenic human orphan virus, is also a member of the enterovirus genus, with 34 serotypes, but 10, 28, 34, 23 and other types belong to other virus genus.

Coxsackie virus and ECHO virus can cause a variety of human diseases, from mild respiratory infections to group B virus-induced myocarditis, pericarditis, meningoencephalitis, and severe infant systemic diseases.

3. What is New enterovirus?

        New enterovirus includes types 68 to 71. These viruses can grow on monkey kidney cells.

        Type 68 was isolated from the respiratory tract of a child with bronchial or pneumonia, suggesting that it is related to both diseases. Type 69 was isolated from a patient in Mexico, and its relationship with human disease remains to be confirmed.

Type 70 is the pathogen of acute hemorrhagic conjunctivitis. Epidemics broke out in Africa and Southeast Asia from 1969 to 1971, and later in Mexico. 

Acute hemorrhagic conjunctivitis is characterized by sudden subconjunctival hemorrhage, from point to sheet bleeding, covering the entire ballar congunctiva, which is easy to diagnose clinically.

The incubation period is 1 to 2 days, and the course of disease is about 8 to 10 days. It is highly contagious. More common in adults. No effective treatment. 

Coxsackievirus A24 variants also often cause acute hemorrhagic conjunctivitis. 

Type 71 was isolated from the feces of a baby with encephalitis in California in the United States in 1969, and the epidemic of the type 71 virus has been reported successively around the world. 

A pandemic also occurred in Taiwan Province of China in 1998, with hundreds of thousands of people infected (> 300,000).

Type 71 virus mainly causes diseases of the central nervous system, such as aseptic meningitis, encephalitis, and poliomyelitis-like paralysis.

Most deaths are accompanied by pulmonary edema and pulmonary hemorrhage. It can also cause hand, foot and mouth disease.

4. What is Acute Gastroenteritis Virus?

        Acute gastroenteritis is the most common disease in humans. According to statistics, about 3.5 million preschool children die each year in developing countries due to diarrhea.

Among biological factors, in addition to bacteria and protozoa, viruses are the main pathogenic factors. It mainly includes rotavirus of the Reoviridae family, Norwalk virus of the Caliciviridae family, small round structured virus (SRSV), and adenovirus. 

Types 40 and 41 of the F genera of the family Adenoviridae and astrovirus of the family Astroviridae.

What is Rotavirus?

       Rotavirus is the most important pathogen that causes gastroenteritis in infants and young children. Every year, 130 million infants and young children suffer from rotavirus diarrhea, with 873,000 deaths.

In 1973, Bishop and others first discovered virus particles, which were shaped like wheels, and named rotavirus from ultrathin sections of duodenal mucosa of children with acute diarrhea.

In 1983, Chinese virologist Hong Tao discovered adult diarrhea rotavirus.

What are Caliciviruses and Astroviruses?

       As early as the 1970s, many viruses, such as Norwalk virus, small circular structure virus (SRSV), and human calicivirus (HuCV), were found in the stools of humans and animals with acute gastroenteritis through electron microscopy And astroviruses.

Nucleic acid sequence analysis of cDNA clones confirmed that Norwalk virus and some SRSV belong to HuCV. 

Epidemiological investigations, human volunteer tests, and laboratory studies have confirmed that HuCV, SRSV and astrovirus are pathogens that cause acute gastroenteritis in infants and young adults.

        The virus is transmitted orally through contaminated food and water sources. It can occur in all age groups. HuCV is susceptible to babies and school-age children, with an incubation period of 12 to 72 hours. SRSV infection is most common in adults.

The incubation period of astrovirus is 3 to 4 days, the course of disease is 1 to 4 days, and occasionally it can last 2 weeks. light. The virus enters the gastrointestinal tract orally and replicates in the jejunum.

The main clinical symptoms are vomiting, diarrhea, fever, abdominal pain, and headache. 

Light microscopy revealed damage to the jejunal biopsy, villi in the small intestine widened and flattened, and lymphocytes and neutrophils increased. 

Electron microscopy showed that the epithelial cells were still intact, but the microvilli were arranged irregularly and became shorter.

What is Intestinal adenovirus?

       Enteric adenovirus (EAd) is an icosahedral stereosymmetric, non-enveloped double-stranded DNA virus with a diameter of 70nm to 75nm. 

It belongs to the human adenovirus F subgenus and includes 40 and 41 serotypes. They are now recognized as one of the important pathogens that cause diarrhea in infants and young children. 

Among them, 41 serotypes are most common. It can occur in all seasons. The main clinical manifestations are watery diarrhea, accompanied by fever. The course of disease can last for 1 to 2 weeks.

Author's Bio

Dr. Shawna Reason

Name: Shawna Reason

Education: MBBS, MD

Occupation: Medical Doctor / Virologist 

Specialization: Medical Science, Micro Biology / Virology, Natural Treatment

Experience: 15 Years as a Medical Practitioner

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