In medicine, the window period for a test designed to detect a specific
disease
A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical condi ...
(particularly infectious disease) is the time between first
infection
An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmis ...
and when the test can reliably detect that infection. In
antibody
An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as pathogenic bacteria, bacteria and viruses, includin ...
-based testing, the window period is dependent on the time taken for
seroconversion.
The window period is important to
epidemiology
Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and Risk factor (epidemiology), determinants of health and disease conditions in a defined population, and application of this knowledge to prevent dise ...
and
safe sex
Safe sex is sexual activity using methods or contraceptive devices (such as condoms) to reduce the risk of transmitting or acquiring sexually transmitted infections (STIs), especially HIV. "Safe sex" is also sometimes referred to as safer ...
strategies, and in
blood
Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells.
Blood is com ...
and
organ donation
Organ donation is the process when a person authorizes an organ (anatomy), organ of their own to be removed and organ transplantation, transplanted to another person, #Legislation and global perspectives, legally, either by consent while the d ...
, because during this time, an infected person or animal cannot be detected as infected but may still be able to infect others. For this reason, the most effective disease-prevention strategies combine testing with a waiting period longer than the test's window period.
Examples
HIV
The window period for HIV may be up to three months, depending on the test method and other factors.
RNA
Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...
based
HIV tests has the lowest window period. Modern and accurate testing abilities can cut this period to 25 days, 16 days, or even as low as 12 days, again, depending on the type of test and the quality of its administration and interpretation.
Hepatitis B
Two periods may be referred to as window period in
hepatitis B
Hepatitis B is an infectious disease caused by the '' hepatitis B virus'' (HBV) that affects the liver; it is a type of viral hepatitis. It can cause both acute and chronic infection.
Many people have no symptoms during an initial infection. ...
infection:
:(1) the period that elapses during HBsAg to HBsAb seroconversion, i.e. between the disappearance of surface antigen (HBsAg) from serum and the appearance of HBsAb (anti-HBs), and
:(2) the period between infection and appearance of HBsAg.
During the window of HBsAg to HBsAb seroconversion, IgM anti-core (HBc-IgM) is the only detectable antibody. HBV DNA may be positive as well. This window period does not occur in persons who develop chronic hepatitis B, i.e. who continue to have detectable HBV DNA for greater than 6 months (HbsAg remains positive), or in people who develop isolated
HBcAb positivity, i.e. who lose HBsAg, but do not develop HBsAb (HBV DNA may or may not remain positive).
See also
*
Incubation period
Incubation period (also known as the latent period or latency period) is the time elapsed between exposure to a pathogenic organism, a chemical, or ionizing radiation, radiation, and when symptoms and signs are first apparent. In a typical infect ...
, the time between infection and the appearance of symptoms
References
{{Concepts in infectious disease
HIV/AIDS
Serology