Protecting vet professionals from Q fever

Q fever is endemic in the UK and has a varying prevalence reported with 80% of positive bulk milk ELISA tests across 225 GB dairy herds¹ and 70% bulk milk PCR positive in south-west England².

It is caused by the highly infectious, intracellular gram-negative bacterium, Coxiella burnetii, which can infect cattle, goats, sheep and many other animals.

Q fever has been dubbed the “subtle disease” as clinical signs often mimic other diseases. However, Q fever should be considered in ruminants if there are increased pregnancy losses and metritis, as well as more subtle fertility issues such as increased days open.

Infectious organisms may persist for many months after shedding, and can be detectable in the immediate environment, such as a calving area or lambing pen, and also on the wool of infected sheep³.

Close contact to the initial source of infection leads to a high risk of infection, although infectious organisms can be transferred to other areas of the farm through human activity⁴.

Coxiella burnetii infection in ticks appears to be geographically variable and as yet there is no evidence of Coxiella burnetii DNA detection in ticks within northern Europe⁵.

While Q fever can affect herd productivity and fertility in dairy herds, it is also zoonotic and can pose a major health risk to those in contact with infected animals including farmers, farming families, vets, animal health professionals (foot trimmers, mobility scorers or vet techs) and abattoir workers.

Infection usually occurs through inhalation of dust or aerosols from the bacterium in the environment that comes from infected placentas and fetuses, as well as animals shedding through milk/faeces and vaginal mucous.

Coxiella burnetii is inactivated by pasteurisation and ingestion of even unpasteurised dairy products is not a primary route of transmission to humans.^{6, 7, 8}.

Subclinical or asymptomatic infection is the most common presentation in humans. However, about 40% of people infected experience flu like symptoms or atypical pneumonia⁹. Like flu, most people infected with the disease recover within two weeks.

Acute Q fever

Hospitalisation as a result of acute Q fever is high¹⁰. Moreover, 4% of people require hospital admission¹¹ with illnesses like hepatitis and meningitis.

Q fever fatigue syndrome (QFS) effects approximately 20% of acute Q fever sufferers, with humans suffering reduced quality of life similar to that seen in chronic fatigue syndrome¹².

Human-to-human transmission of Coxiella burnetii can occur, but is rare¹¹.

Chronic Q fever

 Chronic Q fever develops in less than 5% of people exposed to the infection¹¹ and clinical signs may only show years after the initial infection. Clinical signs of chronic Q fever include non-specific fatigue, fever, weight loss, night sweats, hepato-splenomegaly, vascular complications as well as endocarditis^{13, 14, 15}.

Aneurysm and endocarditis are relatively common and directly contribute to the high rates of 25% mortality in chronic Q fever sufferers¹⁶. In pregnant women, Q fever infection can cause miscarriage or pre-term births^{17, 18}.

Awareness of Q fever in humans is low and there is no human vaccine in the UK. Treatment includes a number of weeks on the broad-spectrum antibiotic, doxycycline.

Case study: My experience with Q fever

I have a very personal reason for being passionate about protecting both livestock and those in contact with animals from this disease as, unfortunately, I have had Q fever and experienced its effects first-hand.

I was in the second year of vet school when I got poorly for the first time. It was February 2013, and I had what felt like a cold, which then developed into constant migraines that wouldn’t go away.

I’d never had migraines before, so I went to the doctors and they started me on migraine treatment, believing that stress was to blame. The migraines continued, but I then developed neurological issues including blurred vision and dizzy spells.

The pain in my head was just unreal and this went on for several weeks while I was being referred to neurology for a variety of tests and scans, with the consultant mentioning that a brain tumour may be to blame.

It was during this time that another person in my year at vet school suggested that I get a test for Q fever as a few people in our year had the disease.

Unfortunately, it was quite hard to get the test done as awareness of Q fever in human medicine was really low at the time. When I did finally have the test, I was told that the results were fine.

My illness continued and it wasn’t until the third or fourth admission to hospital by my doctor that they gave me a print out of my results to take to the hospital with me, which hadn’t happened on previous occasions. I looked over the results and there it was, clear as day; the test showed that I’d gone from a normal titre to a sky-high titre.

When I arrived at the hospital they confirmed that I had Q fever and asked why I wasn’t being treated for the disease. It was at this point that I started antibiotics and I recovered really quickly. However, I had ongoing problems with my heart rate. This was subsequently diagnosed as postural orthostatic tachycardia syndrome (POTS) and it’s taken several years to get my POTS treatment right.

In late 2017, my six-monthly blood titres had started to rise, but I felt fine. Then in January 2018 the same clinical signs started again – constant migraines, blurred vision and dizziness.

I asked to be referred back to the infectious disease department. They started a work up for chronic Q fever, as my antibody titres suggested it had changed from an acute Q fever infection to the chronic form.

Part of the work up involved tests and scans to see whether they could work out where the infection was in my body, as apparently it likes to hide out in blood vessels, which is why the heart is often affected as it likes to “stick” to the heart valves.

Unfortunately, they couldn’t find the source of the infection, but the clinical signs were making life very hard to function, so the decision was made for me to receive treatment for chronic Q fever.

This consisted of 18 months of antibiotics and malaria treatment. I was back to normal again within a few days of being on antibiotics, but they’ve had long-lasting effects on my gut health.

I would recommend that anybody around livestock with ongoing clinical signs, like a cold or a migraine, is tested for Q fever and that the vet and farming industry do all that they can to take preventive measures to minimise exposure to the bacterium.

Working with animals inevitably involves close contact with contaminated material and a common question from a vet practice owner or head vet when a dairy herd tests positive for Q fever is ‘What advice should I give to my employees?’ to help protect them from the disease.

As with a myriad of other zoonotic diseases, the UK Health Security Agency (UKHSA) stresses that good personal hygiene is essential and appropriate measures should be taken to minimise exposure of all those in contact with the infected herd.

All vet practice and farm personnel should be informed of the possible risks and advised on the precautions that should be taken to reduce the risk of catching Q fever. Advice from the UKHSA includes:

• Wash hands thoroughly several times a day (especially if grossly contaminated) and always before eating and after finishing work for the day
• Wash skin wounds immediately with soap and running water and cover with a waterproof dressing
• Treat potentially infected animal tissues, such as afterbirths and aborted material, with care and handle with waterproof gloves
• Use extra personal protective equipment (including facemasks and goggles) for high-risk activities, such as when handling abortions during confirmed Q fever outbreaks, using a pressure washer, or working in very dusty livestock areas.
• Store protective clothing separately from work clothing and do not wear contaminated or dusty work clothing at home
• Use disposable facemasks that conform to EN149-FFP2 standards
• Avoid eating or drinking in animal areas
• Use appropriate protective clothing and tick repellents if exposure to ticks is unavoidable
• Check the entire body daily to promptly remove any attached ticks
• Pregnant women should avoid close contact with livestock that are giving birth or in the postpartum period.

Diagnosis in dairy herds

Accurate diagnostics in ruminants, particularly after bovine abortion, remains challenging and a diagnosis is not reached in the majority of general bovine abortion/still-birth submissions¹⁸.

Diagnostic tests may include PCR in the bulk milk tank and ELISA blood tests. If there is a series of abortions in a herd, PCR on vaginal samples on at least two aborted dams should be taken.

It is essential that the sampling is done within seven days following an abortion and is sent without delay to a veterinary diagnostic centre. The placenta and stomach content of aborted calves can also be sent as sample materials for investigation.

Diagnosis in small ruminants

Small ruminants are normally diagnosed following an abortion with samples sent to a diagnostic centre, however vaginal swabs and serology can also be used.

Vaccination

The cornerstone of Q fever control is vaccination and a vaccine is available that significantly decreases the excretion of Coxiella burnetii, to decrease abortion rates and improve fertility in dairy cows and small ruminants. The vaccine can be safely used in pregnant animals and can help to minimise shedding and protect naive animals.

As I have found out, Q fever in humans can be nasty and can have a long-term effect. The veterinary and farming industry should be doing all they can to protect both the animals in our care and the people that care for them and this includes preventive measures like herd vaccination in animals diagnosed with Q fever and good hygiene procedures.

Bekky Hobbs is director and farm vet at Castle Veterinary Group in Cornwall. She worked for many years as a registered veterinary nurse in a mixed practice in Nottinghamshire before qualifying as a vet and joining Castle Veterinary Group in 2016.