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China's quiet brucellosis outbreak sickens thousands in northwest

Leak at vaccine plant leaves some Lanzhou residents facing chronic illness

Zhu Zhi and his wife Zhou Xing hold up their laboratory results. The couple and their daughter all tested positive for brucellosis. (Photo by Caixin)

Editor's note: Pseudonyms are used in this story to protect the privacy of people affected by the disease in Yanchangbao.

Last September, 40-year-old shopkeeper Gao Hong in Northwest China's Lanzhou city was hit with crippling joint pain and persistent fever. It took nearly six months for doctors to diagnose her condition as brucellosis, an animal-borne bacterial disease.

By then, she had missed the window for the most effective treatment, leaving her with a hard-to-cure chronic condition that requires long-term medication. Since July, it's been hard for her to walk unassisted because of the joint pain.

Gao is among thousands of residents around a biopharmaceutical plant in Lanzhou who were exposed to the highly contagious, hard-to-treat disease as a result of contaminated factory exhaust last summer. Most of the patients tested positive for brucellosis antibodies, but few were formally diagnosed.

Patients said doctors seemed inexplicably reluctant to issue brucellosis diagnoses or to quickly order aggressive treatments. Although local officials maintained that the disease would dissipate over time, many residents are still suffering damage to their health, undermining their quality of life.

"(My) calf swelled to twice the usual size and joints all over my body hurt," Gao said.

Gao's nightmare began at the Lanzhou Biopharmaceutical Plant, a unit of state-owned China Animal Husbandry Industry, located on the northeastern edge of Lanzhou, the capital of Gansu Province. Local health authorities said on Dec. 26 last year that the factory used expired sanitizers while producing Brucella vaccines between July 24 and Aug. 20. This resulted in the bacteria entering the factory's exhaust and infecting people nearby, officials said.

Liu Ming bought his house in Lanzhou in 2017 and didn’t move in until October 2019. He was also infected with brucella bacteria. (Photo by Caixin)

There are more than 10 communities with a combined population of more than 10,000 located within 1 km of the plant. Caixin learned that antibody tests later showed that more than 3,000 people were infected. There is no evidence of human-to-human transmission of the disease.

Brucellosis commonly occurs among sheep, cattle, goats, pigs and dogs. Humans can contract the disease through close contact with infected animal tissue or through ingestion of unpasteurized dairy products from infected animals.

The disease, also known as Malta fever or Mediterranean fever, can cause recurring fever, joint pain and severe headaches, among other symptoms. Chronic brucellosis is especially hard to cure and causes a general fatigue and a persistent fever. Symptoms can last months or even years, and damage human fertility, although the disease is rarely deadly.

Brucellosis spread in China in the 1970s and 1980s but has been effectively controlled. Sporadic outbreaks often appear in pastoral regions such as North China's Inner Mongolia autonomous region. The country's Law on the Prevention and Control of Infectious Diseases lists brucellosis as a class II infectious disease along with AIDS and SARS.

Several people from the Yanchangbao neighborhood around the Lanzhou Biopharmaceutical Plant told Caixin they started showing unexplained symptoms, including low fever and joint pain around September 2019. It wasn't until a Dec. 26 briefing held by the Gansu Provincial Health Commission and the Lanzhou city government that they realized they might have been exposed to brucellosis.

Officials said at the briefing that as of Dec. 25, 181 of 671 blood samples tested positive for brucellosis antibodies among staff members and students at the Lanzhou Veterinary Research Institute in the neighborhood where the disease was first detected. One person showed clinical symptoms, they said.

The government in late December arranged free blood tests and health consultations for residents in the Yanchangbao district, but no test results were made public.

Caixin learned that by the end of February this year, about 20,000 people in Lanzhou received tests for antibodies for the Brucella bacterium. More than 3,000 came back positive.

Local authorities said the leak at the biopharmaceutical plant contained low levels of bacteria that wouldn't harm people's health and would be cleared from the human body within six months. Those who tested positive but showed no symptoms didn't need medical treatment, officials said.

The home of Zhao Renjun, right, home overlooked the pharmaceutical plant where the bacteria came from. Now he and two family members are infected. They later moved away. (Photo by Caixin)

However, Caixin interviews with 40 Yanchangbao residents who tested positive for the disease found that nearly half of them were still suffering symptoms a year after the leak. Only two of those interviewed were officially diagnosed with brucellosis. Those without a confirmed diagnosis said they were puzzled about treatment options and the severity of their infections. The COVID-19 outbreak made getting access to medical resources harder and forced many to postpone treatment.

Since July 16, Yanchangbao residents who previously tested positive received notice from the community asking them to take another test at designated hospitals for review. None of the residents has received the results.

Fears of outbreak

The unusual emergence of brucellosis in urban Lanzhou was first detected at the Lanzhou Veterinary Research Institute, an affiliate of the Chinese Academy of Agricultural Sciences. The institute is less than 500 meters north of the Lanzhou Biopharmaceutical Plant.

Chen Liwei, a postgraduate student at the institution, recalled that a fellow student told her Nov. 29 that "something serious" had happened at the institute.

"Some people were found to be infected with brucellosis, probably related to lab mice," Chen told Caixin.

According to students at the institute, a researcher in mid-November found that some lab mice were infected with Brucella bacterium, and that the two students involved in the research had tested positive for the pathogen. More staffers went for tests and returned with positive results.

Chen tested positive in early December. Five members of her 20-person research team were also infected, she said. At the same time, news of the brucellosis outbreak at the institute started circulating on the internet, fueling fears.

The Veterinary Research Institute halted all operations to trace the infection and disinfect the facility.

"Everyone was panicked, and every corner in the institution was searched," said Bai Jiawen, a researcher.

But the source of the infection could not be confirmed and people were puzzled that many staffers who had no contact with animals were also infected, Bai said.

It wasn't until the Dec. 26 government briefing that people at the institute realized that the bacteria came from the neighboring factory. The briefing confirmed 181 positive antibody results at the institute without giving further updates. Caixin learned from the institute in June that the final number of infections at the facility was around 210.

Jin, 57, her sons and grandchildren have been infected. In the second half of 2019, she developed a rash, which she initially thought was a skin disease. She tested positive in January. (Photo by Caixin)

Following the official confirmation, people in nearby communities flooded into hospitals for testing. The Lanzhou No. 2 Hospital said it tested 1,274 samples between Dec. 28 and Jan. 1. On Jan. 1 alone, the 11 designated institutions tested about 1,000 people, Caixin learned.

Gao Hong received her positive result on Jan. 5. She had had recurring fevers since September that showed no improvement using cold remedies. Gao's son and husband also tested positive but with lower levels of infection.

Liu Ye, a sanitation worker in the Yanchangbao district, was also infected. Six of her 23 co-workers tested positive. "That's only [those] who took the test," Liu said. "There are more who didn't take the test."

Caixin learned that by the end of February, more 3,000 people had tested positive for brucellosis antibodies in almost all age groups, including 213 from the Veterinary Research Institute, eight from the Lanzhou Biopharmaceutical Plant, more than 2,500 residents of nearby neighborhoods and more than 150 people who lived farther from the plant.

Difficult to diagnose

Officials insisted that the contaminated exhaust contained low levels of bacteria and wouldn't damage people's health, even when tests detected antibodies.

Mao Xiaorong, an infectious disease expert at Lanzhou University No. 1 Hospital who participated in the government-run health consultations for Yanchangbao residents, said the patients she examined all had mild symptoms, but some overreacted. But Mao said she couldn't speak for all patients.

The area around the plant where the contamination occurred: Around 3,000 local residents have tested positive for brucellosis antibodies.

A doctor at the Lanzhou No. 2 Hospital painted a different picture. He said the hospital admitted about 100 Yanchangbao residents in late December, "all with relatively severe symptoms." But the patients were confirmed with Brucella bacterium infection based only on antibody tests, rather than being diagnosed with brucellosis.

Diagnosing brucellosis is complicated as it often presents symptoms similar to common diseases like flu and rheumatism. According to the brucellosis treatment standards issued by the National Health Commission in 2019, brucellosis should be diagnosed through epidemiological contact tracing, clinical manifestations and laboratory tests.

Several Yanchangbao residents who tested positive said doctors mostly seemed reluctant to issue a diagnosis of brucellosis, especially as the COVID-19 outbreak intensified. Most doctors offered prescriptions simply to deal with specific symptoms, they said.

Gao Hong is one of the few who was formally diagnosed with the disease. She received a diagnosis in early March after spending months visiting doctors in different hospitals, getting treatments for osteoarthritis or rheumatoid arthritis. The diagnosis came two months after she tested positive for brucellosis.

A doctor told Gao in March that she had missed the best opportunity to treat brucellosis, and her disease developed into chronic brucellosis requiring long-term drug treatment.

Many patients still have not received a diagnosis. Wang Yiyi started to feel unwell in September last year, developing pain and fever. In late December, she tested positive, but no doctor confirmed whether she had contracted brucellosis. She took treatments to ease joint pain, but as the COVID-19 pandemic intensified, Wang gave up visiting doctors and taking medicine. She still suffers pain from swollen joints.

Unknown future

Some people want to receive brucellosis treatment, even without a formal diagnosis. But they are worried abut signing informed consent documents, which would mean any side effects from treatment would be at their own risk.

Common treatments for brucellosis mainly rely on antibiotics that could damage the heart, lungs, liver and kidneys, as well as causing digestive system reactions, circulatory system damage, allergic reactions or nervous system damage, according to a document shown to Caixin by a patient.

In a meeting with Yanchangbao residents, Lanzhou University No. 1 Hospital's Mao said a positive result from an antibody test doesn't necessarily mean a person is ill. She recommended that people without symptoms not take medical treatments. For those who want to voluntarily take treatments, they should bear the risks themselves, Mao said.

On an evening in May, people in Lanzhou flock to the banks of the Yellow River to enjoy the cool weather. (Photo by Caixin)

"The plant poisoned us, and we have to take responsibility for risks of medication," said one resident who was upset about the policy.

Liu Ming decided to undergo voluntary treatment after suffering persistent pain in his lower back since November. He tested positive for Brucella bacterium in January. Liu was admitted to a hospital for antibiotic treatment, which was provided free by the hospital. But due to concerns over the pandemic, he left the hospital after one week.

"There was neither adverse reaction nor improvement," Liu said. He has felt a constant lack of energy, he said.

Several infectious disease doctors told Caixin that brucellosis is very amenable to treatment within six months of infection. But if that opportunity is missed, patients may suffer irreversible damage even after the bacteria is eliminated, they said.

Several Yanchangbao residents told Caixin that they received follow-up phone calls from the community about their health, but no further information or assistance was provided.

At the Veterinary Research Institute, students discussed whether they could take legal action.

"But the lawyer said it would be a tough fight, and the compensation wouldn't be high," Chen Liwei said.

Meanwhile, some students at the institute are reluctant to come forward because any public record of their illness could affect their careers in animal-related businesses. According to industry rules, people with a history of zoonotic diseases -- that is those that move from animals to humans -- are barred from veterinary or animal husbandry employment.

For some people in Yanchangbao, the infection has caused more pain than physical illness. A woman who was two months pregnant tested positive in January and was warned by doctors that there would be risks in delivering the baby. In June, the woman told Caixin she had an abortion.

For other parents, the deepest concern is whether the infection posed health risks to their children.

Zhang Cuiping, a cleaning lady in her 50s, said the fatigue caused by the bacteria has made it increasingly difficult for her to do her job. Zhang's four family members also tested positive. However, "there is no time to think about [the disease], as we have to earn money to pay the mortgage," Zhang said.

People close to local authorities said the Lanzhou government in March issued an internal report regarding compensation payment to those affected by the bacteria leak, but a formal policy has yet to be published.


Read also the original story. is the English-language online news portal of Chinese financial and business news media group Caixin. Nikkei recently agreed with the company to exchange articles in English.

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