Researchers from the Fraunhofer Institute for Cell Therapy and Immunology IZI were able to prove that ticks transmit the causative agent of Q fever. The tick droppings, in which the bacteria are found in high concentrations, play a particularly important role.
Q fever is one of the notifiable diseases in the EU. It is a zoonosis, i.e. a disease that can be transmitted from animals to humans and is caused by the bacterium Coxiella burnetii is triggered. The bacterium infects cattle, sheep and goats, among others, and veterinarians and animal owners in particular have an increased risk of infection. About half of those infected experience flu-like symptoms. These can be complicated by inflammation of the lungs, liver, heart muscle or brain. Chronic disease progression, mainly heart valve inflammation, is rare but feared because of the severity of the disease.
For Germany, the Robert Koch Institute noted a total of 2018 Q fever cases in its "Infection Epidemiological Yearbook" for 93; according to the "Q fever - Annual Epidemiological Report", published by the European Center for Disease Prevention and Control, 794 cases were reported across Europe Cases reported as confirmed. “All in all, the number of cases is not very high. However, around 100 people have died in the Netherlands in the last ten years as a result of Q fever, although the disease can be treated very well with antibiotics," explains Dr. Gustavo R. Makert dos Santos, who led the studies in the Vaccine Technologies working group at Fraunhofer IZI. The biggest problem from his point of view is that doctors often still have too little knowledge of Q fever and would therefore not diagnose the disease accordingly. This was one of the reasons the interdisciplinary consortium Q-GAPS (www.q-gaps.de), which is funded by the Federal Ministry of Education and Research. The Fraunhofer IZI is involved here in order to work together with human and veterinary physicians to address as yet unsolved questions in connection with Coxiella burnetii to clarify and to conduct enlightenment.
One of these unresolved issues concerned tick transmission. Until now, there has been disagreement in scientific circles as to whether ticks play a role as vectors, i.e. as carriers of diseases. Studies at the Fraunhofer IZI have now shown that ticks act as vectors. And the team around Dr. Gustavo R. Makert dos Santos out. The ticks pick up the bacterium when they bite infected cattle, sheep or goats, and nine days later Coxiella burnetii detectable in tick droppings for at least seven weeks.
The scientists use an in-vitro feeding system specially developed at the Fraunhofer IZI for verification. The ticks were kept in this and fed with infected blood. They also found out that nymphs – after the larva, the second developmental stage of a tick – that were fed infected blood also transmit the bacterium after they have molted to become an adult tick. With another blood meal of uninfected blood, the researchers found Coxiella burnetii afterwards in the feces of the ticks, but not in the pathogen-free blood that the ticks had sucked on. This suggests that Coxiella burnetii is transmitted less by the bite of the tick than by its faeces, e.g. B. about inhaling the same.
Against the background of a changing climate and a further spread of ticks, Makert dos Santos describes the situation as follows: “Due to globalization, significantly more pathogens are traveling around the world. But since the vectors have often been missing up to now, they have not been able to establish themselves. As soon as vectors such as ticks and mosquitoes continue to spread, the risk of contracting pathogens such as Coxiella burnetii To infect.” A better knowledge of Q fever by medical professionals is therefore very important for the diagnosis and treatment of this disease.
The article published in the journal »Parasites Vectors« »Uptake and fecal excretion of Coxiella burnetii by Ixodes ricinus and dermacentor marginatus ticks.« summarizes the results of the study (doi: 10.1186/s13071-020-3956-z).
The article was also published in the "Berliner und Münchener veterinary weekly journal" in April 2020 »Coxiella burnetii: A review article with a focus on the infection process in German sheep and goat herds« (doi: 10.2376/0005-9366-19030).
Source: Press release from Fraunhofer IZI from April 28.04.2020, XNUMX