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Chinese institutes investigate pathogen outbreaks in lab workers

Students and staff at two research institutes have tested positive to the Brucella bacterium, which can lead to serious complications.

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A Thai Livestock Officer Throws Bodies of Goats Infected in the First Major Outbreak of Brucellosis.

Outbreaks of brucellosis, caused by the bacterium Brucella, often occur in farm animals.Credit: Rungroj Yongrit/EPA/Shutterstock

Two Chinese agriculture research institutions are investigating how more than 100 students and staff became infected with the bacterium Brucella, strains of which are typically found in farm animals but can also trigger potentially fatal complications in people.

The Lanzhou Veterinary Research Institute in central China confirmed on 7 December that 96 staff and students have tested positive for the infection. In a statement, the institute said most of the infected people are not experiencing signs of brucellosis, the illness caused by the bacterium, which can include fever and flu-like symptoms.

The institute says it has closed its labs following the outbreak. Although some mice have also tested positive to the infection, an investigation has yet to announce the strain of Brucella in the infected people, or the source of the outbreak.

On 10 December, the health commission for the province of Heilongjiang confirmed that 13 students at the Harbin Veterinary Research Institute, around 2,600 kilometres to the northeast of Lanzhou, also had the infection. The 13 students were among 49 students who had previously worked as interns at the Lanzhou institute. The Harbin institute says it is also investigating the outbreak.

Different types of Brucella occur in many mammals species, but infections are most commonly detected in farm animals such as goats, sheep, cattle and pigs. Human infections most commonly result from the ingestion of undercooked meat or raw milk — but the bacteria can also enter the body through the lungs or skin wounds. Brucella strains are not typically transmitted from person to person. If left untreated, the infection can travel to the heart or brain and, in rare cases, be fatal. It can also cause infertility in animals and humans.

The outbreak at the Lanzhou Veterinary Research Institute was first uncovered in November when some students in the institute‘s foot and mouth disease research unit noticed that large numbers of their lab mice were infertile, according to The Beijing News. The mice tested positive for Brucella, as did four students. The institute then tested 317 people, and found that 96 had been infected.

The Beijing News also reported that students at the institute often forgo wearing masks and taking other precautions.

The research institutes in Harbin and Lanzhou did not respond to Nature’s questions about how the outbreak occurred, or their lab‘s safety procedures.

Lab-acquired infection

The US Centers for Disease Control says brucellosis is the most commonly reported bacterial infection acquired in scientific laboratories. Several factors contribute to the risk of infection, such as working on the pathogen without bio-safety-level-3 conditions which recommend closed laboratory safety cabinets, masks, a positive-pressure ventilation system and other precautions. The bacterium is also easily transmitted in aerosols. In 2011, 28 students and staff at an agricultural university also in Heilongjiang province, were infected with Brucella from goats. They each received 61,000 yuan (US$8,740) in compensation.

Felipe Francisco Tuon, coordinator of the Laboratory of Emerging Infectious Diseases at the Pontifical Catholic University of Paraná in Curitiba, Brazil, says that outbreaks in laboratories are usually found to be linked to insufficient safety precautions.

doi: 10.1038/d41586-019-03863-z

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