Immunosenescence is an age-related malfunction of the immune system, which could be accompanied by an increased susceptibility to infections. Many infections occur more common in older individuals and it could be associated with higher morbidity and mortality. During senescence, physiological condition provides situation that causative agents causing infection change, and there is a shift in organisms involved during infection and
comorbidies of infection with greater diversity are more common than those occurred in younger adults. Increased risks and acquiring many types of infections with severe clinical outcome occurred in part due to impairment of immune defenses that might be aggravated by chronic infections, malnutrition, and prolonged medication received during ageing.