A biosecurity blunder in the Netherlands left a lab worker hospitalised with typhoid, MailOnline can reveal.
The mishap occurred during the height of the Covid pandemic but details have only come to light now.
Scientists claimed the incident proved how easily lab-acquired infections can occur, even in facilities with strict safety measures.
The unidentified lab worker was only spotted after going to casualty complaining of a headache and fever of ‘unknown origin’.
Tests initially ruled out anything sinister, prompting doctors in Amsterdam to send them home.
Details of the lab-acquired infection in Amsterdam were published in the Diagnostic Microbiology and Infectious Disease earlier this month. But medical centre and research institute Amsterdam UMC told MailOnline that the incident occurred in early 2021 around Spring. It did not share the exact name or location of the laboratory in Amsterdam, or state if it happened at one of its own sites
Samples of the bug were sent to the Dutch Government’s infectious diseases lab. Analysis revealed the lab worker had salmonella typhi, a ‘highly contagious’ bacteria which causes typhoid fever. Pictured, a conceptual image of salmonella typhi causing typhoid
But they were called back 36 hours later by the hospital after blood tests taken by medics at OLVG Amsterdam at the time ended up being positive for salmonella.
The bacteria were also detected in faecal samples taken by the worker.
Samples of the bug were sent to the Dutch Government’s infectious diseases lab for further analysis.
Results revealed the lab worker had salmonella typhi — a highly contagious bacterium which causes typhoid fever.
Sharing details of the incident in a medical journal, the doctors admitted they were baffled because the employee had ‘no history of travel to an endemic country or contact with patients with typhoid fever’.
In hope of solving the riddle of how they caught typhoid, medics contacted the lab worker’s employer.
It transpired that the worker had experimented with a salmonella sample at a BSL-2 lab two weeks before they became ill — roughly how long it takes to develop typhoid’s tell-tale, cold-like symptoms.
Biological safety levels (BSL) are ranked from one to four based on the agents or organisms laboratory workers are researching.
While BSL-1 applies to labs working with low-risk microbes that pose little threat of infection in healthy adults, for instance some strains of E.coli, BSL-4 labs work with highly dangerous and exotic microbes, including Ebola.
Widely-known BSL-4 labs include Porton Down in the UK and the Wuhan Institute of Virology, central to the Covid ‘lab leak’ theory.
Safety protocols in BSL-2 labs involve personal protective equipment (PPE) including face shields, self-closing, lockable doors and performing procedures which could cause infection from aerosols or splashes in a biological ‘safety cabinet’.
Follow-up genetic tests of the bacteria revealed it was the same strain, indicating that it was a ‘lab-acquired infection’.
Writing in the report, experts, including some from the Amsterdam University Medical Center (UMC), said: ‘Despite ongoing improvements in biosafety, lab-acquired infections do occur incidentally.
‘This incident occurred despite good laboratory precautions.’
No breach of biosafety protocols was uncovered, with experts still confused as to how they caught it given the bacteria is not airborne.
Details of the lab-acquired infection in Amsterdam were published in the Diagnostic Microbiology and Infectious Disease earlier this month.
But medical centre and research institute Amsterdam UMC told MailOnline that the incident occurred in early 2021 around Spring.
It did not share the exact name or location of the laboratory in Amsterdam, or state if it happened at one of its own sites.
Dr Gregory Koblentz, an expert in biodefence at George Mason University, stated the lab should be commended for tracking down the origin of the infection.
However, because they could not identify how the worker got infected the incident ‘cannot be used to draw wider conclusions about risk of lab-acquired infections’, he added.
Professor Mark Stevens, chair of microbial pathogenesis at the University of Edinburgh, meanwhile said ‘the most likely explanation was that it was acquired in the laboratory’.
He told MailOnline: ‘This does not necessarily indicate a leak from the lab. It is not airborne and liquid spills would have been contained in the cabinet.
‘If the technician touched liquid or solid media on which the bacteria were growing, then inadvertently touch their mouth or failed to wash hands properly, that could suffice.
‘Lab-acquired accidents are rare. While risks are assessed and control measures are applied, potential for human error cannot be eliminated.’
Professor Willem van Schaik, director of the Institute of Microbiology and Infection at the University of Birmingham, said: ‘These infections do happen, but are fortunately very rare as laboratories need to follow strict biosafety rules.
‘I expect Dutch authorities will have made significant efforts to review procedures in this laboratory.’
He added: ‘For the organism Salmonella Typhi, this case in Amsterdam appears to be only the fourth reported laboratory-acquired case this century, with three of them having been reported in a South African laboratory with problematic biosafety procedures.
‘In contrast, more than 10million people are thought to be infected with salmonella typhi every year, with the consumption of water and food that is contaminated with the bacterium being the most common routes of infection.’
Experts only said that the employee had handled salmonella cultures in a ‘biosafety cabinet’ — a ventilated enclosure which uses High Efficiency Particulate Air (HEPA) filters to clean air going into the work area and out to the environment.
The worker underwent 14 days of antibiotic treatments in hospital, before he ‘fully recovered’, experts said.
It is not the first time lab workers have fallen ill after biosecurity blunders.
In 1972, a laboratory worker at the London School of Hygiene and Tropical Medicine contracted smallpox after poor biosecurity measures were enforced in the lab.
They went on to infect three others, killing two.
Meanwhile in 2014, inadequate laboratory safety led to potential exposure of 75 staff to anthrax at the Centers for Disease Control and Prevention (CDC) Roybal campus in Atlanta.
Typhoid is typically spread through touching contaminated surfaces, with the bug found in poo and urine.
The fever is most common in parts of the world that have poor sanitation and limited access to clean water. But it can be prevented through vaccination.
Without prompt treatment, the highly contagious infection can cause serious complications and can be fatal.
Common symptoms of the infection include a persistent high temperature that gradually increases each day, headaches, fatigue, constipation and general aches and pains.
But it is normally only travellers visiting countries such as Bangladesh, India or Pakistan, who choose to get the jab.
Approximately 21 million cases and 222 000 typhoid-related deaths occur annually worldwide, according to the World Health Organization.
Typhoid fever is uncommon in the UK, with around 300 infections confirmed each year.
In the US each year, around 350 people are diagnosed with typhoid fever, according to the CDC.
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