Zhu Ling (, 24 April 1973 – 22 December 2023) was the victim of an unsolved thallium poisoning case in Beijing, China. In late 1994, while studying chemistry at Tsinghua University, she was poisoned; she subsequently fell into a coma in 1995. Her symptoms were posted online via a Usenet newsgroup by her friend Bei Zhicheng from Peking University, and were reviewed and diagnosed by physicians around the world. Although Zhu’s life was saved, she suffered severe neurological damage and permanent physical impairment.
The investigation was closed in 1998 for lack of evidence and went cold until it drew renewed public attention in the 2010s, becoming one of the most high-profile cases in China and giving rise to widespread speculation and conspiracy theories.
Poisoning First hospitalization In 1994, Zhu Ling was a sophomore in Class Wuhua 2 (Class 2 majoring in physical chemistry) at Tsinghua University in Beijing. Classmates described her as attractive, intelligent, and musically talented. She began to show strange and debilitating symptoms on 24 November 1994, when she reported acute abdominal pain, and loss of appetite. On 5 December she again experienced stomach discomfort, and her hair began to fall out.
On the night of 11 December 1994, despite her illness, Zhu Ling insisted on performing with the Tsinghua University Chinese Orchestra at the Beijing Concert Hall, where she played a Guqin solo of the piece "Guangling San." She had to wear glasses because her eyes were painful and at times she could not see at all. Her hair fell out completely within a few days of the performance.
Zhu was admitted to Beijing Tongren Hospital on 23 December 1994. Her condition gradually improved, she was allowed to return to school, and she was discharged on 23 January 1995.
Second hospitalization A new semester began on 20 February 1995. On 27 February, shortly after returning to school, Zhu experienced intense pain in both legs. Her condition deteriorated further on 6 March, with severe leg pain and dizziness, and her parents took her to Peking University Third Hospital for treatment. Professor Chen Zhenyang (陈震阳), who was involved in her diagnosis and treatment, recorded in his paper "Introduction to a Rare Case of Severe Thallium Poisoning" that on 8 March Zhu "once again experienced intense foot pain, pain in the calves, so severe that she dared not touch any objects. This time it was more severe than the before, and the condition developed rapidly, extending to the lower back."
On 9 March 1995, Zhu Ling's parents took her to the neurology clinic at Peking Union Medical College Hospital (PUMCH). After examining her, Professor Li Shunwei (李舜伟), told Zhu's mother that her condition was "very similar to a case of thallium poisoning at Tsinghua University in the 1960s." In the medical record for that day, Li described Zhu's condition as follows: "(the patient is) mentally clear and articulate, experiencing significant hair loss, limbs hurt by touching, redness at the fingertips and soles which are not swollen but with elevated temperature. Reduced sensation in the fingertips and below the knees, with a symmetric knee reflex. Ankle reflex is slow. Highly suspicious of heavy metal poisoning, such as thallium and beryllium, consulted with Director Zhang Shoulin and professors, including Ding Maobai. On admission, Zhu "had clear Mees' lines on her fingernails, raising suspicion of possible thallium poisoning".
To clarify the diagnosis, Li contacted Professor Zhang Shoulin at the Chinese Academy of Medical Sciences. That same day, Zhu, accompanied by her mother, was examined by Zhang, who suspected acute thallium or arsenic poisoning; the institute, however, was unable to conduct the necessary tests. Zhu denied any contact with thallium in class, a claim confirmed by Tsinghua's chemistry department. PUMCH also cited a lack of equipment to perform such tests, and so–at the hospital where the future suspect Sun Wei's mother worked—no thallium test was carried out.
Diagnosis and treatment On 15 March 1995, Zhu was admitted to the neurology ward of PUMCH, presenting with "hair loss, abdominal pain, and joint and muscle pain for three months, pain in the distal ends of both lower limbs for seven days; and dizziness for three days". The admission note recorded that she had had abdominal pain without an obvious cause for three months before admission (from 8 December 1994), characterized by continuous dull pain with intermittent colicky pain, and that hair loss had occurred, accompanied by soreness in both shoulders and the knee joints. The initial diagnosis was"peripheral neuropathy; cause of limb pain and redness to be determined". The Lumbar puncture performed on the same day yielded normal results. A neurology consultation the next day ruled out autoimmune diseases, poisoning, and metabolic disease, and PUMCH treated her for Guillain-Barré syndrome.
After admission, her condition worsened rapidly. It affected her chest, her facial muscles became distorted, and her speech grew unclear. She was unable to drink water without choking, and breathing difficulties emerged. Treatment involved broad-spectrum antibiotics, antiviral drugs, corticosteroids, immunosuppressants, and albumin injections, among other measures.
Zhu fell into a coma on 20 March. On 23 March she developed central respiratory failure and PUMCH performed a tracheotomy. After a comprehensive neurology discussion the same day, the diagnosis was revised to acute disseminated encephalomyelitis (ADEM), and treatment involved plasma-exchange therapy.
PUMCH began plasma-exchange therapy on 24 March, continuing until 18 April, for a total of seven sessions. Each session involved 1,400-2,000 milliliters of plasma, amounting to about 10,000 milliliters in total. Some commentators believe this played a crucial role in sustaining Zhu's life in the absence of a confirmed diagnosis; during this process, however, Zhu contracted Hepatitis C.
On 28 March, Zhu Ling developed a pneumothorax in the left lung and was transferred to the Intensive care unit (ICU) at PUMCH, where her breathing was supported by a ventilator. A comprehensive neurology consultation was held on 3 April, with experts from PUMCH, PLA General Hospital 301, Boai Hospital, Beijing Hospital, and other institutions. The consultation concluded that the current diagnosis and treatment were appropriate. Afterwards, Zhu's parents learned from some of the experts that, because thallium poisoning had been ruled out, the consultation had felt obliged to explore other possible causes.
Zhu Ling remained in a coma for five months, awakening only on 31 August. PUMCH conducted numerous tests, including for HIV, lumbar puncture, magnetic resonance imaging (MRI), immune system evaluations, chemical poisoning assessments, anti-nuclear antibodies, nuclear antigen antibodies, Lyme disease, and urinary arsenic. All results were negative except for Lyme disease. During this period, the hospital told Zhu's family that thallium poisoning could be "ruled out".
Diagnosis via the Internet Frustrated by local physicians' inability to help Zhu Ling, her friends Cai Quanqing and Bei Zhicheng, undergraduates at Peking University, posted an "SOS" letter on a number of Internet Usenet groups on 10 April 1995, describing her symptoms and asking for help with a diagnosis. By 1995, only a few research institutes in the People's Republic of China had Internet connections, among them the laboratory of Cai's advisor. Responses began arriving within hours, and news reports hailed the event as a milestone in remote diagnosis by Internet, especially within China. Of the more than 1,500 responses Zhu's friends received, roughly one-third suggested thallium poisoning, whose common antidote Prussian blue.
Because of the limited Internet infrastructure in China, Dr. Li Xin, a Chinese student at UCLA, and Dr. John W. Aldis of the U.S. Embassy in Bejing collaborated to establish the UCLA Zhu Ling Thallium Poisoning Telemedicine Network. In 1996, Li and his colleagues published a paper describing the construction and operation of this remote-diagnosis system and its significant role in the case. Bei Zhicheng, Cai Quanqing, and others uploaded Zhu's case information—including photographs taken at the onset of the illness, laboratory results, neurological findings, and radiographic images such as chest X-rays and brain MRIs. Li and his colleagues at the UCLA School of Medicine set up servers to store the data and to collate and categorize emails received from around the world, allowing medical experts internationally to review Zhu's condition and reply with follow-up questions for diagnostic and treatment suggestions.
According to the diagnostic and treatment logs at UCLA, as early as April 10, the day Bei Zhicheng sent the email, there were doctors responding with a diagnosis of thallium poisoning. Dr. Robert Fink, a neurosurgeon in the United States, believed that heavy metal poisoning was highly probable. However, PUMCH replied at that time, stating that all laboratory tests related to heavy metal poisoning had been conducted. With further communication, American doctors eventually discovered that PUMCH had only performed screening tests for metal arsenic. As time went by, more medical experts believed that thallium poisoning could not be ruled out and insisted that Peking Union Medical College Hospital should promptly conduct screening for metal thallium. Doctors from St. Jude Children's Research Hospital pointed out in their response, "Suspected Thallium poisoning can be nearly diagnosed based on symptoms such as hair loss, gastrointestinal problems, and neurological issues". Dr. Fink recalled that as Zhu Ling's condition worsened, they urged PUMCH through various channels to conduct thallium poisoning screening for a quicker and more accurate diagnosis. At that time, in addition to leveraging connections at the U.S. Embassy in Beijing, they directly faxed relevant academic articles to PUMCH. Dr. Aldis also personally communicated with old friends who were healthcare professionals at PUMCH.
On Apr 18, 1995, Bei Zhicheng brought the translated emails to the ICU of PUMCH to provide to the doctors as a reference. There was no proactive response. Few people reviewed it, and the diagnosis of thallium poisoning and the corresponding testing methods mentioned in the email were not adopted. This resulted in the delayed impact of the online remote diagnosis at that time.
When Zhu Ling's parents requested the doctors to consider the opinions presented in the email, PUMCH doctors responded with, "We have the ability to consult international medical databases". They also mentioned "Peking University students bring many problems". Many years later, when Bei Zhicheng had a heated online debate with Sun Wei in 2005 on Tianya BBS, he wrote, "The former director of the ICU at Peking Union Medical College Hospital refused to conduct further tests for heavy metal poisoning. Even after the misdiagnosis at Peking Union Medical College Hospital was discovered, he showed no remorse. Astonishingly, he said at a hospital meeting that 'This matter is an attempt by Western anti-China forces to discredit the Chinese medical community'".
Dr. Aldis documented in Zhu Ling's medical records: until May 16, Bei received nearly 2000 emails. On the other hand, Bei and his friends at Peking University attempted to provide PUMCH with a modem, hoping to facilitate direct communication with overseas medical professionals. Unfortunately, due to some "non-technical reasons," all their attempts were unsuccessful. Dr. Aldis expressed deep regret at the limited communication channels between overseas doctors and PUMCH at that time, which hindered the exchange of information regarding Zhu Ling's diagnosis and treatment.
Subsequent diagnosis and treatment