Which type of infectious agent is more likely to affect patients with Selective IgA deficiency?

Selective IgA deficiency is a condition characterized by an impairment in the immune system's ability to produce Immunoglobulin A (IgA), which is crucial for mucosal immunity. This antibody plays a vital role in protecting mucosal surfaces like those in the respiratory and gastrointestinal tracts, where many pathogens enter the body.

Patients with Selective IgA deficiency often have an increase in the risk of infections, particularly from bacteria that colonize mucosal surfaces. Bacterial pathogens, such as those responsible for respiratory and gastrointestinal infections, can exploit the lack of IgA, as these bacteria often rely on IgA for opsonization and neutralization. Thus, individuals with this deficiency are more susceptible to bacterial infections compared to other types of infections.

While patients may also experience higher rates of viral, fungal, and parasitic infections, the predominant concern associated with Selective IgA deficiency relates to bacterial infections. The absence of adequate IgA allows bacteria that typically would be neutralized by it to cause illness more frequently and severely. Therefore, the increased vulnerability to bacterial infections is a defining characteristic of individuals with this immunological condition.