Recent programs such as Hulu’s “The Act” and the HBO documentary “Mommy Dead and Dearest” have introduced audiences to a dangerous and often overlooked phenomenon: Munchausen’s syndrome by proxy.

It is a mental health problem in which a caregiver causes an illness or injury to a vulnerable person – often a child. The disorder is difficult to diagnose and treat. Here are key facts about Munchausen syndrome by proxy, or MSBP.

What is it?

The symptoms of MSBP manifest as child or elder abuse, depending on the circumstances. Officials at the National Institutes of Health describe MSBP as “a special form of child abuse in which an adult repeatedly produces symptoms of illness in a person under his/her care.”

Health professionals distinguish MSBP from Munchausen syndrome, a condition in which people intentionally harm themselves or purposely self-induce illness to satisfy a desire to be cared for. With MSBP, the perpetrator (often a mother) will inflict such symptoms on a child or elder as a way to inspire sympathy from others.

The methods used to garner such attention from others can range from simple lies about an illness to actual physical harm — even poisoning — of the victim.

Health officials say the victim may have been initially healthy but face the risk of becoming seriously ill or even dying in the care of someone with MSBP.

Studies cited by the NIH report a mortality rate between 6 percent and 10 percent for MSBP victims, making it one of the “most lethal forms of abuse.”

The current medical term for such an illness is Factitious Disorder Imposed on Another, although it is more commonly referred to as MSBP. The phenomenon is relatively rare in the U.S. — making up just 1,000 of the approximately 2.5 million cases of child abuse reported annually.

Health experts said it is notoriously difficult to identify and properly treat Munchausen’s syndrome by proxy. People with the disorder are known to be great liars and master manipulators.

One method they use is to alter medical tests and results to make it seem as if the person in their care is sicker than they truly are. People with MSBP can get away with this, health experts say, because they often are familiar with medical terms and concepts.

This could explain why many cases of abuse caused by people with MSBP can go undetected by medical staff and law enforcement for long periods of time.

Online organizations such as the Munchausen Syndrome by Proxy Survivor Support and Awareness Group on Facebook provide those affected by MSBP with a community to vent and to heal.

Two cases of MSBP involving young mothers in Virginia have been publicized in recent years. In both instances, the perpetrator was arrested on child abuse charges.

One case involved a 23-year-old woman whose 3-year-old son was being treated in 2016 at the Children’s Hospital of the King’s Daughters in Norfolk for “ongoing medical issues.”

The woman was arrested after video surveillance from her son’s room showed the young mother allegedly detaching medical equipment being used to give the boy vital medicine. The judge overseeing her case said there was reason to believe the woman gave doctors false information about her child’s medical records.

Earlier this year, 29-year-old Elizabeth Malone admitted to purposely poisoning her 5-year-old son with syringes of her own blood while he was being treated at Inova Fairfax Hospital last spring. She said she did so because she “liked the way staff responded to him once he was bleeding.” Video footage from a security camera shows Malone injecting blood into her son’s IV line and tracheostomy tube.

Had she not been caught, according to doctors, it is likely that her child would have died from the injections, which resulted in high fevers and infections. Malone, who has two other children, will be sentenced in July.