Infection medicine

Bacteria, viruses and parasites have been with us humans since ancient times. They will be our “companions” in the future, for as we defeat some diseases, new diseases emerge or old re-emerge from the shadows. Most human infections are zoonotic, meaning that they occur mainly in animals but also have the capacity to cross species boundaries and infect humans. At the Section for infectious diseases we use a multidisciplinary approach to study zoonotic infections and antibiotics resistance in our new platform the Zoonosis Science Center.

Our research has a broad base and we focus currently on the following areas:


Josef Järhult, Anna Gillman, Erik Karlsson, Per Eriksson, Patrik Ellström, Björn Olsen

During the last century, Influenza A virus (IAV) caused three pandemics. In 1918-1920, the Spanish Flu killed at least 50 million people. All pandemic viruses contain avian genetic material achieved through a re-assortment process. There are two different strategies used in treatment and prophylaxis of IAV. First, vaccines are effective but the production of vaccines is slow, and second antiviral drugs like the neuramidase inhibitors oseltamivir (OC) (Tamiflu) and zanamivir (ZA) (Relenza). OC is stable in water and not removed or degraded in sewage treatment plants. In the downstream water, ducks, the natural reservoir of IAV, are exposed to OC resulting in resistance induction of viruses in their gastrointestinal tract. With mallards as an animal model and by virological, chemical and molecular techniques we have detected induction of resistance in IAV and retention of resistance mutations in repeated replications and transmission without drug pressure. Our results will be of value for organizations and authorities working with strategic pandemic preparedness planning, like the WHO.

Review article

Tick borne infections

Erik Salaneck, Tove Hoffman, Mats Lindeborg, Björn Olsen

Birds fly. This fact makes them extremely important as vehicle and transmitters of various parasites and potential carriers of pathogenic microorganisms. The new concept “ornithological-medicine” is a research area that will give new insights into the ecology, epidemiology and infection biology of vector borne infections in general and tick born infections in particular. A basic knowledge on the mechanisms of the spread of and occurrence of zoonoses will be very important for agriculture and veterinary medicine. Borrelia spp and Ehrlichia spp. can cause infections in animals and humans and therefore basic research on the biology, pathogenicity and virulence of tick borne zoonoses is important. We will study the importance of seabirds and terrestrial birds in the dispersal of the tick borne pathogens. Further, by developing infection models we can study the interaction, virulence, pathology, and infection biology between host, vector and microorganism.

Campylobacter and other gastrointesitinal pathogens

Campylobacter is our most common zoonotic infection and most human cases can be attributed to the broiler industry. Despite years of research efforts, we still know very little about how Campylobacter reach the food industry, how they survive in the environment or how they transmit between species and cause disease in humans. In our group, we study barriers for transmission of Campylobacter between species. We also study bacterial virulence factors associated with different outcome of infection as well as the role of the gut microbiota in Campylobacter infection. In 1995 we discovered that Campylobacter can survive and replicate in free living amoebae and currently we focus on understanding the role of such protozoans as environmental reservoirs for these bacteria. Campylobacter are globally abundant and wild birds are important hosts. Anywhere there are birds, there seem to be Campylobacter. During a number of expeditions, we have isolated Campylobacter even in Antarctica. Currently, we study the ecology of Campylobacter in these remote areas.

Amoeba, Photo:Diana Axelsson Olsson

Antibiotic Resistance in natural bacterial flora

Jonas Bonnedahl, Josef Järhult, Badrul Hasan, Johan Kaarme, Åsa Melhus, Eva Tano, Björn Olsen.

The main force behind emergence of antibiotic resistance is the use of antimicrobial agents in human and veterinary medicine and domestic animal husbandry.

However, there is also evidence that epidemic spread of drug-resistant bacteria and horizontal transfer of resistance genes are contributing factors to resistance emergence. It is important to realize that there are no closed systems, the bacteria we select for in environments close to humans will find their way to bacterial communities in nature and vice versa. The knowledge of antibiotic resistance in the environment is limited and we need to explore this field and link it to consumption of antibiotics in our societies.

Photo: Evangelos Mourkas

We have brought together experts in different fields to evaluate how bacterial resistance is transferred and maintained within all potential reservoirs, including humans, domestic animals, wildlife and the environment. Our strengths complement each other in terms of methodological and practical skills, and in our team we have physicians, veterinarians, ecologists, micro- and molecular biologists, and environmental chemists.

Spotted fever rickettsiosis; diagnostic procedures, prevalence in vector and mammal hosts and association to clinical disease

Karin Elfving, Katarina Wallmenius, Anders Lindblom, Carl Påhlson, Kenneth Nilsson

Rickettsia in a Vero cell.

The spotted fever group of rickettisae has a world-wide distribution and different species are established depending on the geographic area. Migrating birds may however contribute to a long-distance dispersion of bacteria, and also to an inflow of novel and potentially pathogenic rickettsia species into countries. Rickettsia felis is usually transmitted by fleas while R. helvetica is the only tick-transmitted rickettsia found free in nature where the tick Ixodes ricinus represents the most important potential vector. R. helvetica is the most prevalent and is found endemic in tick populations and there is a need to consider infections when investigating disease after a tick bite. We have shown that patients may present a flu-like self-limiting mild febrile disease sometimes with prolonged fever as well as subacute meningitis or peri myocarditis. Growth characteristics and morphology of R. helvetica were studied to better understand invasiveness and virulence. We found that invasiveness is comparable with other rickettsia, though R. helvetica seems to have a stable but slightly slower growth.