An investigation into an outbreak in q fever

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This report intends to investigate an outbreak of Q fever which occurred in a small rural abattoir. It will also outline health and safety procedures which were present in the abattoir, as well as the etiology of Q fever, in addition to methods of prevention and whether this outbreak could have been avoided.

Q fever is caused by a bacterium called Coxiella burnetii, which can affect both humans and animals. C.burnetii mostly infects cattle, sheep, and goats. This disease is a zoonotic disease, meaning it is passed from animals to humans. Infection normally occurs by inhalation of endospores from barn yard dust contaminated with dried milk, faeces, urine, and placental material. This organism is resistant to heat, drying and many common disinfectants. ( Only approximately half of people infected with C.burnetii show symptoms. Symptoms of Q fever include high fevers (104-105 F), headaches, feeling generally uncomfortable or uneasy, confusion, throat pain, sweating, chills, coughing, vomiting, diarrhoea, as well as abdominal or chest pain. These symptoms usually last for 1-2 weeks. Q fever has an incubation period of 2-4 weeks ( Chronic Q fever can develop and is potentially more serious, with high fatality rates if left untreated. This is often associated with underlying or pre-existing conditions. The most common complication of chronic Q fever is endocarditis (inflammation of the endocardium within the heart, this condition also effects the heart valves) ( Q fever is normally treated by antibiotics, most notably doxycycline. This is most effective when taken within 3 days of the illness developing, and is taken orally twice daily, for 15-21 days. This disease generally affects veterinarians, meat processing plant workers, dairy workers, and farmers ( In the UK there are around 70 cases of Q fever reported annually; however in 2006 there were more than 100 cases reported during an outbreak of Q fever in a meat processing plant in Bridge of Allan, Scotland (HPS report). The largest outbreak in the UK occurred in Solihull in 1989, where 147 cases were reported. This is believed to be associated with windborne spread from farmland to an urban area (Smith et al, 1993).

Background of the abattoir being investigated

In the current investigation an outbreak of Q fever occurred at a small rural abattoir. Over a two week period approximately 25% of the work force fell ill with a non specific respiratory illness, later diagnosed as Q fever. The outbreak was reported to the health and safety executive (HSE) under the current reporting of injuries, diseases and dangerous occurrences regulations (RIDDOR). This is required by law, and enables the HSE to identify and investigate serious accidents. In turn this allows them to provide advice and support on how to reduce injury and ill health in the workplace ( Exposure of workers to zoonoses also needs to be minimised as required by the control of substances hazardous to health regulations (COSHH) 2002. COSHH requires the employers to assess the risks to health involved in potential exposure to a hazardous substance, prevent exposure to hazardous substances or where this is not possible control the amount of exposure to the dangerous substance. These control measures must also be maintained. Safety training on the risks to employees and the precautions to be taken by employees must also be provided. Finally these measures must be regularly reviewed (

Aims and methods of investigation

This report is being carried out by an independent consultant reporting back to the HSE, who will then make a decision on possible prosecution if they feel that offences have been committed under the health and safety at work act. This report aims to find out if;

This even could have been reasonably foreseen and prevented

The current safety precautions that are currently in place

This report will also carry out a risk assessment to minimise the chances of another outbreak.

The investigative process began by obtaining a list of employees infected with Q fever and their telephone numbers, as well as a list of their main working area in the abattoir were obtained from the abattoir management. Infected employees were then contacted and interviewed via telephone. Verbal consent was obtained from each employee, and the aims of the investigation made clear to them. Employees were asked a series of questions that sought to elucidate information on the possible source of exposure to C.burnetii. Results of this survey seemed to indicate the source of the infection came from the lairage (Animal handling facilities, which include loading and unloading ramps, weigh scales, holding pens, and feed bunkers). It was noted that a higher incidence of illness occurred in people who whose areas of work were near the lairage.

Environmental samples were obtained from the boning and slaughter areas, as well as the animal pens, air vents, and lairage. This was analysed using polymerase chain reaction (PCR) for the presence of C.burnetii. This test confirmed the presence of C.burnetii bacteria on one of the walkways which led into the meat processing area.

The combination of data from the employee interviews and the environmental data makes the lairage, more specifically the walkway from the holding pens to the abattoir, the most probable source of contamination; this may be due to leakage in to the communal courtyard, or possibly from inadequate cleaning of the walkway.

Safety precautions taken by the abattoir

The abattoir in question had a number of safety precautions in place, protective clothing was provided to workers (including gowns, wellington boots and hard hats). In addition to this all staff were required to wash and sterilise hands when moving between different areas of the abattoir, and also required to walk through sterile foot baths. All personal protective equipment (PPE) is regularly maintained and cleaned and stored in a clean area. That abattoir also regularly assesses ventilation systems regularly as they have the potential to disperse micro organisms such as C.burnetii. This may be done fans creating positive pressure within lairage buildings and forcing potentially polluted air into work areas. Lairages and ventilation systems are positioned away from communal area to reduce the chances of exposure. Further safety measures taken by the abattoir in question include informing workers of the symptoms of Q fever, the likely sources of infection, the control measures that can be taken to reduce exposure, and what action to take in the event of an outbreak including appropriate RIDDOR regulations. Further notices are displayed that indicate the importance of good occupational hygiene, such as washing hands before eating, drinking, smoking, going to the toilet, and at the end of the shift. There are also areas where workers can wash, cleanse and dry hands. This is also echoed in notices stating the importance of having any cuts or grazes covered with a waterproof dressing, to avoid infection. It was noted however that these notices were in English only, and that the abattoir has a number of migrant workers whose ability to read and understand these notices may be compromised by English not being their first language.

As Q fever is generally caused by occupational exposure, it is always possible that those who work with cattle, sheep and goats could become infected. It is for these reasons, in addition to the safety procedures described above that this report believes that this outbreak of Q fever could not have been reasonably foreseen.

Possible improvements

Further personal protection equipment (PPE) may reduce the chances of contracting Q fever. Respiratory equipment (EN149-FFP3) ( may reduce the chances of inhaling contaminated material. In addition to this screening employees for pre existing health conditions such as conditions which compromise the immune system, vascular conditions, or are in receipt of transplanted organs.

Risk assessment

A risk assessment was carried out use the health and safety executives five step advice (

Step 1

This involves identifying the hazards which exist in the workplace (in this case the focus is on the bacterium C.burnetii, the cause of Q fever). Initially a walk around the abattoir while looking for obvious hazards was carried out. Employees were also asked to identify any hazards in their working environment. In addition to the manufacturers guidelines on PPE and chemicals involved with disinfection of the abattoir were investigated. This was done to check that the safety equipment was being used in the correct manner. Accident log books were also looked at, to see what accidents had occurred in the past.

Step 2

This step involves identifying both workers and visitors to the abattoir who may be harmed, in addition to how they may be harmed. Workers were divided into different groups, and risks to these groups were identified i.e. what type of health issue or injury may occur (e.g. Workers involved with butchering the meat, may be exposed to reproductive tissue which contains high numbers of C.burnetii). Some workers may have particular requirements such as pre existing health conditions which may put them at particular risk of infection by C.burnetii. Visitors to the abattoir are also made to wear PPE, and have a full health and safety briefing before entering the abattoir.

Step 3

This step involves dealing with hazards that were found in stage 1. Health and safety law requires that everything reasonably possible is done to protect individuals from harm. This can be worked out by the person carrying out the risk assessment, but comparing what is being done to current best practice guides is a good idea. These can be found at It is also prudent to look at what is already being done to meet health and safety standards, and compare it to these best practice guides. Consideration should be given to see if a hazard can be removed altogether, for example, restricting access to a hazard such as the lairage, issuing further personal protective equipment, and providing facilities for washing and showering for the removal of contamination.

Step 4

Step 4 involves the recording and implementing of findings made in previous steps. This should be done in as simple a manner as possible. The document that is produced should be shown to all staff. The law states that if a company employs 5 employees or less than no risk assessment document needs to be created, though it is advisable to do so to allow review of the risk assessment.

Step 5

This step involves the review and updating of risk assessment if necessary. This step is essential as workplaces are in a state of constant change, whether it is changes in employees or changes in the recommended PPE.


This report concludes that the abattoir in question could not have reasonably prevented the outbreak of Q fever. Reasonable precautions were taken to ensure the safety of workers, including PPE, disinfectant baths between areas of the abattoir, and information on correct hygiene procedures. This report has however offered some suggestions as to how to improve current health and safety standards in the abattoir.