Due to immunity acquired in childhood, most adults are not susceptible to rotavirus; gastroenteritis in adults usually has a cause other than rotavirus, but asymptomatic infections in adults may maintain the transmission of infection in the community. Virology
Transmission
Rotavirus is transmitted by the faecal-oral route, via contact with contaminated hands, surfaces and objects, and possibly by the respiratory route. The faeces of an infected person can contain more than 10 trillion infectious particles per gram;  fewer than 100 of these are required to transmit infection to another person.Rotaviruses are stable in the environment and have been found in estuary samples at levels as high as 1–5 infectious particles per US gallon. Sanitary measures adequate for eliminating bacteria and parasites seem to be ineffective in control of rotavirus, as the incidence of rotavirus infection in countries with high and low health standards is similar. Types
There are five species of rotavirus, referred to as A, B, C, D and E. Humans are mostly infected by species A. All five species cause disease in other animals. Within rotavirus A there are different strains, called serotypes. As with influenza virus, a dual classification system is used based on two  proteins on the surface of the virus. The glycoprotein VP7 defines the  G serotypes and the protease-sensitive protein VP4 defines P serotypes. Because the two genes that determine G-types and P-types can be passed on separately to progeny viruses, different combinations are found.
The embryo, then the fetus and then the baby will have what is called a 45,X/46,XY constitution. This is called a
mosaic karyotype because, like tiles in mosaic floors or walls, there is more than one type of cell.There are many chromosomal variations that cause the 45,X/46,XY karyotype, including malformation (isodicentricism) of the Y chromosomes, deletions of Y chromosome or translocations of Y chromosome segments. These rearrangements of the Y chromosome can lead to partial expression of the SRY gene which may lead to abnormal genitals and testosterone levels. Diagnosis
Identification of 45,X/46,XY karyotype has significant clinical implications due to known effects on growth, hormonal balance, gonadal development and histology. 45,X/46,XY is diagnosed by examining the chromosomes in a blood sample. The age of diagnosis varies depending on manifestations of disease prompting reason for cytogenetic testing. Many patients are diagnosed prenatally due to fetal factors (increased nuchal fold, or abnormal levels of serum), maternal age or abnormal ultrasounds, while others will be diagnosed postnatal due to external genital malformation. It is not uncommon for patients to be diagnosed later in life due to short stature or delayed puberty, or a combination of both.45,X/46,XY mosaicism can be detected prenatally through amniocentesis however, it was determined that the proportion of 45,X cells in the amniotic fluid cannot predict any phenotypic outcomes, often making prenatal genetic counselling difficult. Management
See also
Gonadal dysgenesis
Mosaic (genetics)
Turner syndrome

References


== External links ==