The three-and-a-half-year-old Jerusalem boy whose mother allegedly neglected and starved him until he weighed only 7 kilos - the weight of a five-month-old baby - has gained 20 percent of his weight since nearly two weeks ago, when the mother was arrested. "Physically, he is on the right track," said Dr. Yair Birnbaum, deputy director-general of the Hadassah Medical Organization. The Hadassah administrator explained that the boy, from the Mea She'arim quarter's Toldot Aharon hassidic community, was likely to recover physically with good care, but it was not certain what his traumatic experience would do to him mentally and psychologically. He is being fed orally and by gastric tubes, enabling him to gain 1.7 kilos since entering Hadassah-University Medical Center at Ein Kerem. Meanwhile, Birnbaum said that some hassidim had threatened the hospital, saying they would persuade others not to give birth or get other medical care at Hadassah and would demonstrate there en masse. The Toldot Aharon community has claimed the woman is not guilty of abuse and has objected to her arrest. The father, a yeshiva student who has three other children, has visited the boy occasionally, but has refused to talk to the hospital staffers. Birnbaum said on Wednesday that the boy had learned how to walk, but that the starvation had made it difficult for him to move beyond lying in bed. Before her arrest, the mother had been detaching his feeding tube in the pediatric ward, the hospital realized. The mother reportedly suffers from Munchausen's-by-proxy, a rare syndrome that involves the exaggeration or fabrication of illnesses or symptoms by a primary caretaker. In this mental illness, an individual - usually a mother - deliberately makes another person (usually her or his own preschool child) sick or convinces others that the person is sick. The parent or caregiver misleads others into thinking that the child has medical problems by lying and reporting fictitious episodes. The toddler had originally been hospitalized several times at Hadassah-University Medical Center on Mount Scopus, and after repeated tests, consultations and assessment, the hospital doctors reached the conclusion that it was not cancer, an immunological problem or any other physical illness that had caused him to "fail to thrive." "Before filing a complaint to the social welfare services, we had to have proof," Birnbaum said, adding that "perhaps we could have reached the conclusion a week or so earlier. But abuse is a very complicated phenomenon to recognize and demonstrate." Meanwhile, Eda Haredit spokesman Shmuel Poppenheim charged on Wednesday that the child had been given chemotherapy treatment for nearly a year during his hospitalization at Hadassah, due to concerns that he was suffering from cancer. However, Hadassah spokeswoman Yael Bossem Levy categorically rejected the claim. Etgar Lefkovits contributed to this report.