Q Fever: a very consequential query
By Dr Felicia Pradera and Miss Madeleine Walters
Q fever has recently generated a significant amount of nationwide attention with the rise of farm lobby campaigns for access to the Q fever vaccination and the development of a Q fever National Taskforce. Nonetheless, in the medical countermeasures domain, Q fever has long been of niche interest to scientific researchers.
Q fever was first described in Queensland in 1935. It was dubbed ‘query fever’ as the symptoms were non-specific, consisting of malaise, fever, headache and chills. Infection is caused by the pathogen C.burnetii, commonly transmitted to humans through contact with contaminated agricultural products or exposure to infected livestock.
C.burnetii is highly infectious because of its small inoculum size, meaning only 1.18 bacterial particles of C.burnetii are needed to develop a Q fever infection. The bacteria can also survive for a long time in soil or dust, due to its ability to adapt to harsh environmental conditions, thus increasing the risk of infection. This also means it can travel considerable distances when dispersed by wind, increasing the spread of infection. Due to this high infectivity and the ability C.burnetii has to cause such indiscriminate but serious flu-like symptoms – making it hard to discern from other viral infections such as influenza – it has been listed as a Category B Biological Threat Agent by the US Centre for Disease Control and Prevention (CDC). Q fever has the potential to pose an equally significant threat to public health as it does to the health of military personnel in endemic regions.
Historically, Q fever was studied as an aerosolized threat in both the US and former USSR biological offensive programs. In the US, Operation Whitecoat involved the trial exposure of conscientious objectors to airborne bacteria containing C.burnetti at Fort Derrick during the 1950s and 1960s.
During the Iraq war deployment in 2003, Q fever was identified as a military health threat for the US as it is endemic to the Middle East. In addition, 90 US military cases were reported through the US Army Centre for Health Promotion and Preventative Medicine from January 2007-June 2008. There were also reports of Q fever infection in UK forces operating in Helmand Province, Afghanistan in 2008. Adding to the complexity of Q fever is the fact that it can be difficult to diagnose. The infection’s incubation period can be relatively long (up to 2-3 weeks) and antibodies can take up to several weeks to develop. Furthermore, a chronic form of the illness (Chronic Q) develops in some cases, which can be harder to diagnose than the initial infection. Chronic Q fever occurs in around 10 % of Q fever cases, according to figures provided by the NSW Government. The diagnostic process for Chronic Q is still being refined, as in culture and serum based PCR positive results only occur in approximately 50-60 % of affected patients.
Chronic Q can also cause further physiological complications for the patient. One of the main complications is endocarditis, a potentially fatal condition of the inner lining of the heart. Other associated complications include hepatitis and chronic fatigue syndrome. Significantly, the disability adjusted life-years associated with chronic Q fever is estimated to be between 8-28 times more severe than occurred in H1N1 influenza patients.
In recent years, there have been increasing incidences of widespread outbreaks of Q fever. The largest outbreak recorded was in the Netherlands during 2007-2010, where approximately 4,000 cases were reported, although it was estimated that there were as many as 40,000 cases. It was thought that this outbreak occurred because of the location of contaminated dairy and goat farming close to heavily populated urban areas. More recently, in 2019 there was a Q fever outbreak in Spain attributed to human contact with infected animals.
Over the last decade in Australia there have been on average 472 Q fever cases per year. Since 2010, the number of Q fever cases has increased from 338 in 2010 to 531 in 2019. In order to treat C.burnetii infection, the development of reliable and safe medical countermeasures should be a high national priority. It is a threat to both the wider public and military, especially in rural Australia and for those who work with the livestock industry. While significant progress has been made in the diagnosis and prevention of Q fever, a lot about this disease is yet to be understood.
Q Fever is attracting increased national attention. As recently as its meeting on 31 October and 1 November 2019, the COAG Health Ministers’ Council resolved that a national approach to Q Fever control is a topic of concern and asked the Australian Health Ministers’ Advisory Council (AHMAC) to consider the development of a national approach to Q Fever control. The National Farmers Federation is also pushing to see Q fever listed as a public health threat in Australia. There have also been calls for the development of a new vaccine, as well as requests to improve access to the current Q fever vaccine and companion diagnostic by listing them on the Pharmaceutical Benefits Scheme (PBS).
The complex nature of this pathogen and the broad spectrum of the population who could be infected requires a whole of government approach to tackling this disease. Stakeholders may include State Governments and advocacy groups such as the National Farmers Federation, this collaborative engagement may be the best way forward to ensure that action is taken to reduce the threat of Q fever infection in Australia and prevent the debility that can follow infection with this elusive condition.
UPDATE – In August 2020 the Minister for Regional Health, the Hon Mark Coulton MP, announced an investment of $1.87 million from the Department of Health into DMTC’s MCM initiative to accelerate work on a new, non-reactogenic vaccine candidate. Read more here.Posted by Emily Kibble on February 19th, 2020 Tagged: agriculture, C.burnetii, chronic fatigue, disease, DMTC, livestock, Q fever, Q fever national taskforce, rural