Principles of dietotherapy
Since the development of diarrhea in viral gastroenteritis is predominantly driven by a hyperosmolar mechanism, dietary correction is a crucial step in treatment. Diet therapy serves as the absolute foundation for successful recovery.
Key dietary rules:
- Elimination of dairy products. Milk is completely removed from the patient's diet.
- Restriction of plant-based foods and carbohydrates. The consumption of fresh fruits, vegetables, and carbohydrate-rich foods must be strictly limited.
Drug support
Pharmacotherapy is pathogenetic and symptomatic in nature. It aims to relieve symptoms and assist the digestive system.
- Multienzyme preparations. Used to restore the normal enzymatic status of the gastrointestinal tract. Creon, Mezim Forte, Panzinorm Forte, Festal, and Pancreatin are widely used in clinical practice.
- Antispasmodics, adsorbents, and astringents. This group of drugs has proven clinical efficacy. Drotaverine or papaverine are prescribed to relieve spasms, while Smecta, Polyphepan, and carbolen are used as sorbents.
- Probiotics. Preference is given to preparations based on lactobacilli. Acilact, lactobacterin, or bactisubtil are typically included in the treatment regimen.
Pathogen characteristics: Caliciviruses
A significant proportion of viral gastroenteritis cases are caused by caliciviruses (CV), named after the Latin word calyx (cup). These are small, round, RNA-containing viruses measuring about 27–40 nm, belonging to the family Caliciviridae.
All human enteric caliciviruses are classified based on morphological, genetic, antigenic properties, and genome organization. Two main genera are distinguished:
- Noroviruses. The prototype is represented by Norwalk-like viruses (NLV).
- Sapoviruses. The prototype is Sapporo-like viruses (SLV).
An important biological feature of caliciviruses is their high environmental stability. At the same time, neither noroviruses nor sapoviruses are cultivated on standard tissue cultures. This fact greatly complicates the detailed study of the mechanism of human cell damage and the overall pathogenesis of the disease.
Genetic classification
Currently, the viruses are subdivided into at least 3 genotypes.
Noroviruses:
- Pathogenic for humans (I and II genotypes). The first genotype (GI) includes 7 clusters (from GI/1 to GI/7). The second genotype (GII) is more extensive and consists of 8 clusters (GII/1 - GII/8).
- Non-pathogenic for humans (III genotype). Includes only 2 clusters and causes gastroenteritis exclusively in animals, particularly in pigs and cattle.
The criterion for distinguishing clusters is differences in two regions of the genome: the RNA-dependent RNA polymerase region and the zone responsible for capsid proteins. Notably, the amino acid sequence identity of noroviruses within a single cluster reaches about 80%, whereas across the entire genome it is only 44–55%.
Sapoviruses: Differ from noroviruses by higher genome conservation. As with noroviruses, only representatives of genotypes 1 and 2 are pathogenic to humans.
Briefly: answers to topical questions
What laboratory diagnostic methods are used to verify norovirus infection?
Methods for detecting viral antigens in stool and specific antibodies in blood are used to verify the infection.
Depending on the stage of the disease, the following methods are used:
- Latex agglutination assay — examination of coprofiltrate for viral antigens, performed in the early stages (first days of the disease).
- Enzyme-linked immunosorbent assay (ELISA) — blood test to detect specific antibodies, used in later stages.
Class and exam questions
Is there specific prevention for viral gastroenteritis caused by caliciviruses?
Currently, specific prevention is absent because vaccines are still in the development stage.
Why is it difficult to study the pathogenesis of norovirus infection?
The main problem is that noroviruses and sapoviruses are not cultured on tissue culture, which significantly complicates laboratory research.
What serves as the basis of the diet in viral gastroenteritis?
The main rule is the complete exclusion of milk, as well as strict restriction of carbohydrates, fresh vegetables, and fruits due to the hyperosmolar nature of diarrhea.
What else to study on this topic
- Mechanism of hyperosmolar diarrhea formation in viral infections
- Comparative characteristics of norovirus and sapovirus genetics
- Functions of RNA-dependent RNA polymerase in members of Caliciviridae
- Structure of calicivirus capsid proteins and cluster separation criteria
- Features of using lactobacillus-based probiotics
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