The largest global Q fever outbreak ever took place in the Netherlands between 2007 and 2011, and is still resulting in deaths. This is evident from the latest update of the National Chronic Q fever Database in which 116 deaths were reported in the latest update, compared to 95 in 2018. At that time, a very large number of people became infected with the Q fever bacterium Coxiella burnetii. Q fever is caused by this bacterium that passes from animals to humans, a so-called zoonosis. In most people the bacteria disappear from the body, but not in everyone. In that case we speak of chronic Q fever.

Since then, data from patients with chronic Q fever have been collected in the National Chronic Q fever Database, a collaboration of UMC Utrecht, Radboudumc and Jeroen Bosch Hospital. The team consists of Jan Jelrik Oosterheert, internist-infectiologist, Chantal Bleeker-Rovers professor of infectious disease outbreaks and physician-microbiologist Peter Wever, respectively. They have supervised several researchers who, in addition to their responsibility in collecting the data, have conducted research in areas such as improving the diagnosis and treatment of this chronic infection.

Updated figures

The data for almost all hospitals in the Netherlands has been aggregated again. Meanwhile, the chronic Q fever database counts 585 chronic Q fever patients (350 with a proven chronic Q fever infection, 97 with a probable chronic Q fever infection and 138 with a possible chronic Q fever infection). This is 66 more than were recorded in 2018. It is notable that even 10 years after the end of this major outbreak, new cases of chronic Q fever have continued to be diagnosed in patients who were infected years ago.

Mortality

Of the 585 chronic Q fever patients, 107 patients have died as a result of or related to chronic Q fever. Since the last update in 2018 (86 deaths), 21 more have been added. With the already known 9 deaths due to acute Q fever during the outbreak, this brings the total number of deaths to 116. In the group of 350 patients with proven chronic Q fever infection, over 29 percent died from the infection. Because the diagnosis of chronic Q fever was often missed due to unfamiliarity with the infection, the actual number of deaths due to Q fever will be higher. These data show that an outbreak can cause new victims for a long time afterwards. The prevention of Q fever and other zoonoses remains therefore of great importance in order to prevent illness and death in humans.

Chantal Bleeker-Rovers, Professor of Outbreaks of Infectious Diseases at Radboudumc, is one of the supervisors of the database study and treats many patients with chronic Q fever: "With the focus on corona, other infectious diseases seem to be taking a back seat. Unfortunately, they still play a role in society. This certainly applies to Q fever as well. Every year we still see people become infected and die as a result of Q fever. That is why it remains very important to pay attention to this disease. Research is a crucial part of this."

Jan Jelrik Oosterheert PhD is an internist-infectiologist at UMC Utrecht: "With this collaboration and the National Database Chronic Q fever, there is an improvement in diagnostics and treatment of this zoonosis with serious consequences. It has taught us that bundling expertise in the field of infectious diseases is essential to better treat serious infections."

National Chronic Q fever Database

The Dutch Q fever outbreak, the largest ever to occur in the world, resulted in a significant number of chronic Q fever patients. The National Chronic Q fever Database has been collecting data on all chronic Q fever patients from 45 hospitals since 2010. Chronic Q fever is a rare disease and due to the limited number of patients, performing scientific research in this group is complicated. The database is a collaboration between UMC Utrecht, Radboudumc and Jeroen Bosch Hospital led by internist-infectiologist Jan Jelrik Oosterheert (UMC Utrecht), internist-infectiologist Chantal Bleeker-Rovers (Radboudumc) and physician-microbiologist Peter Wever (Jeroen Bosch Hospital) who are responsible for the content of the database. Jesper Weehuizen is the fourth PhD student who has updated the National Chronic Q fever Database and is trying to answer research questions with the data from the database. Researchers Linda Kampschreur, Sonja van Roeden and Bianca Buijs preceded him and have already successfully completed their PhD projects.