Gruppe Basso

Main research line: Diagnosis and epidemiology of infections by cyst-forming coccidian parasites in domestic and wild animals

The cyst-forming coccidia (Apicomplexa, Sarcocystidae) are a group of protozoan parasites characterized for undergoing indirect life cycles with asexual replication and development of cysts in extraintestinal tissues of their intermediate hosts and sexual multiplication and production of oocysts in the intestine of their definitive hosts. This group includes parasites of major importance in veterinary and human medicine, such as Neospora caninum, Toxoplasma gondii, Besnoitia spp. and Sarcocystis spp.

T. gondii and N. caninum infections represent major causes of abortion in small ruminants and cattle, respectively. Ruminants may become infected either through ingestion of oocysts shed with the faeces by the definitive hosts (i.e. felids for T. gondii; domestic dogs, dingoes, coyotes and wolves for N. caninum), or by transplacental parasite transmission from the dam to the foetus. Whereas cattle and other ruminants are the main intermediate hosts of N. caninum, all warm-blooded species (birds and mammals, including humans) are potential intermediate hosts of T. gondii. Carnivorous and omnivorous animals may as well become infected through consumption of tissues from infected hosts, in which the parasites persist quiescently within tissue cysts, mainly in muscular and neural tissues.

In pigs, T. gondii infections are frequently subclinical; however, chronically infected pigs, as well as other meat-producing animals such as ruminants and game, play an important role in public health because they represent important sources of T. gondii infection for humans through consumption of undercooked meat. In humans, toxoplasmosis can cause serious illness especially after congenital infections or in immunosuppressed patients. The European Food Safety Authority (EFSA) recognized toxoplasmosis as the parasitic zoonosis with the highest human incidence and as one of the major causes of food-borne disease worldwide.

Besnoitia besnoiti is the causative agent of bovine besnoitiosis, a chronic debilitating skin disease that may have a fatal outcome and can be associated with orchitis and infertility in bulls. In Switzerland, it is a reportable disease, within a national eradication program.

Sarcocystis spp. infections may be subclinical or associated with fever, weakness, cyanosis, dyspnoea, neurological signs, abortion and/or death depending on the Sarcocystis and host species. Some Sarcocystis species are zoonotic.

The high clinical and economical significance of these parasites as cause of disease in animals and humans encouraged the research on their biology, epidemiology, and clinical implications, and pointed out the need for development of immunological and molecular tools to improve the routine diagnosis and epidemiological research.

Research Projects

Toxoplasma gondii and Neospora caninum infections in South American camelids (SAC), small ruminants, and cattle in Switzerland

Aims of this research project are (i) to estimate the occurrence and distribution of T. gondii and N. caninum infections in SAC, goats, sheep, and cattle in Switzerland; (ii) to optimize serological tests for diagnosis; (iii) to identify risk factors, which may favour infection with these protozoa; (iv) to assess the association of T. gondii and N. caninum to cases of abortion and reproductive failure in these animal species, and (v) to investigate the molecular epidemiology of these parasites.

Oral fluid as matrix for indirect diagnosis of Toxoplasma gondii infection in pigs

Toxoplasma gondii-infected pigs play a major role as a source of infection for humans. Detection of high-risk herds is essential to implement control measures at the farm level, in order to reduce the prevalence of infection. In recent years, sampling of oral fluid (OF) from pigs for diagnostic purposes using cotton ropes has gained interest and OF already has been used as a matrix for screening of several viral and bacterial swine infections, either by direct detection of pathogens or by indirect detection of specific antibodies. The aims of this project are to determine whether oral fluid (OF) could be used as a matrix for indirect diagnosis of T. gondii infection in pigs, and to which extent OF-based methods could represent alternatives to standard serology.

Toxoplasma gondii infection in protected wild mammals in Switzerland: lynx (Lynx lynx) and beaver (Castor fiber)

Aims of the project are to assess the prevalence, epidemiology, and impact of T. gondii infections in Swiss lynx and beavers; (ii) to assess risk factors for infection; and (iii) to investigate the molecular epidemiology of T. gondii in these wild mammals.

Further research lines

Avian malaria and other haemosporidian parasites in captive birds and white storks (Ciconia ciconia)

Avian malaria is a vector-borne disease caused by Plasmodium species, which may affect a broad spectrum of bird families worldwide. In most endemic and migratory birds, Plasmodium infections seem not to cause severe harm; however, non-indigenous species kept in human care such as penguins and puffins may experience high morbidity and mortality rates.

Aims of the study are (i) to identify infections by haemosporidian parasites (Plasmodium spp., Haemoproteus spp. and Leucocytozoon spp.) in captive birds and free-living white storks in Switzerland, (ii) to characterize the involved parasites at the molecular level, and (iii) to assess the clinical significance of these infections.

Strongyloides stercoralis infections in dogs

Strongyloides stercoralis is a worldwide-distributed intestinal nematode affecting mainly humans and dogs. Canine strongyloidosis is generally characterised by diarrhoea, malabsorption, and bronchopneumonia, and may be fatal in cases of impaired immunity. In recent years, molecular and epidemiological studies suggested that host-adapted populations of S. stercoralis with different zoonotic potential may exist. Clinical and subclinical cases of S. stercoralis infection have been increasingly diagnosed in imported and locally born dogs in Switzerland, showing that this parasite is currently circulating in Europe. The aims of the project are to investigate the occurrence, clinical, therapeutic, molecular, and zoonotic aspects of this parasite infection in dogs.

Occurrence of endoparasites in reindeer (Rangifer tarandus) in Switzerland and actual management situation in Swiss breeding farms. 

Aims of the project are to investigate the occurrence of endoparasites in the Swiss reindeer population, and to get information on the local husbandry and management practices, in order to support breeders and practising veterinarians in making appropriate recommendations for parasite control and sanitary management.