Final answer:
CMV infection's key risk factor is that newborns may be asymptomatic at birth, despite a risk of developing symptoms later on. It can lead to serious health issues, especially in immunocompromised individuals, and is diagnosed via serological tests or more sensitive methods like PCR.
Step-by-step explanation:
The characteristic or risk factor associated with Cytomegalovirus (CMV) infection is the high percentage of infected infants being asymptomatic at birth but potentially developing symptoms later in life. While a majority, approximately 80%, of these infants will never have symptoms or long-term problems, there is still a significant risk for the development of conditions such as hearing loss, visual impairment, or neurodevelopmental disorders as they grow. CMV is a congenital infection that can have severe consequences if the virus crosses the placenta during the embryonic state, potentially leading to growth reta_rdation, jaundice, deafness, blindness, and mental ret_ardation.
For those with weakened immune systems, such as transplant recipients or patients with AIDS, CMV can cause serious disease. The diagnosis of CMV is typically made through serological tests, and in severe cases, it can be detected using more sensitive methods such as PCR to determine viral load. An important characteristic sign of a CMV infection in tissues, which reflects its cytopathic effect, is the presence of enlarged cells with 'owl's eye' inclusions upon microscopic examination.