Mycobacterial infections in wild boars (Sus scrofa) from Southern Switzerland: Diagnostic improvements, epidemiological situation and zoonotic potential.

The occurrence of mycobacterial infections in different hosts and their implication as obligate or opportunistic pathogens remain mainly unclear. In addition to the well-known pathogenic members of the Mycobacterium tuberculosis - complex (MTBC), over 180 non-tuberculous mycobacteria (NTM) species have been described. Although the large majority of the NTM is assumed to be non-pathogenic to most individuals, an increasing trend in NTM infections has been observed over the last decades. The reasons of such augmentation are probably more than one: improved laboratory diagnostics, an increasing number of immunocompromised patients and individuals with lung damage are some of the possible aspects. Mandibular lymph nodes of 176 hunted wild boars from the pre-Alpine region of Canton Ticino, Switzerland, were collected. Following gross inspection, each lymph node was subjected to culture and to an IS6110 based real-time PCR specific for MTBC members. Histology was performed of a selection of lymph nodes (n = 14) presenting gross visible lesions. Moreover, accuracy of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) species identification was compared with sequence analysis of a combination of housekeeping genes. Mycobacteria of the MTBC were detected in 2.8% of the wild boars (n = 5; CI95% 1.2-6.5) and were all confirmed to be Mycobacterium microti by molecular methods. In addition, based on the examined lymph nodes, NTM were detected in 57.4% (n = 101; CI95% 50.0-64.5) of the wild boars originating from the study area. The 111 isolates belonged to 24 known species and three potentially undescribed Mycobacterium species. M. avium subsp. hominissuis thereby predominated (22.5%) and was found in lymph nodes with and without macroscopic changes. Overall, the present findings show that, with the exception of undescribed Mycobacterium species where identification was not possible (3.6%; 4/111), MALDI-TOF MS had a high concordance rate (90.1%; 100/111 isolates) to the sequence-based reference method.

PREVALENCE OF CHLAMYDIACEAE AND TETRACYCLINE RESISTANCE GENES IN WILD BOARS OF CENTRAL EUROPE.

Our aim was to investigate the occurrence and distribution of Chlamydia suis and other Chlamydiaceae in the wild boar (Sus scrofa) population of Switzerland and Northern Italy and the detection of tetracycline resistance genes by PCR. We collected a total of 471 conjunctival swabs (n=292), rectal swabs (n=147), and lung tissue samples (n=32) belonging to 292 wild boars. The prevalence of Chlamydiaceae in the investigated wild boar populations was very low (1.4%, 4/292). We found C. suis in rectal or conjunctival swabs but not in lung samples. The low chlamydial prevalence might be attributed to limited contacts between wild boars and outdoor domestic pigs due to strict biosecurity measures or limited numbers of rural pig herds. The tetA(C) gene fragment was detected in six samples, which were all negative for Chlamydiaceae, and was probably not of chlamydial origin but more likely from other bacteria. The low tetracycline resistance rate in wild boar might be explained by the lack of selective pressure. However, transmission of resistance genes from domestic pigs to wild boar or selective pressure in the environment could lead to the development and spread of tetracycline-resistant C. suis strains in wild boars.

Stability of the southern European border of Echinococcus multilocularis in the Alps: evidence that Microtus arvalis is a limiting factor.

SUMMARY The known range of the zoonotic fox tapeworm Echinococcus multilocularis has expanded since the 1990s, and today this parasite is recorded in higher abundances throughout large parts of Europe. This phenomenon is mostly attributed to the increasing European fox populations and their invasion of urban habitats. However, these factors alone are insufficient to explain the heterogeneous distribution of the parasite in Europe. Here, we analysed the spatial interrelationship of E. multilocularis with the known distribution of seven vole species in Ticino, southern Switzerland. Among 404 necropsied foxes (1990-2006) and 79 fox faecal samples (2010-2012), E. multilocularis was consistently found in the north of the investigated area. No expansion of this endemic focus was recorded during the 22 years of the study period. This stable endemic focus is coincident with the known distribution of the vole species Microtus arvalis but not, or only partly, with the distribution of the other autochthonous vole species. Our results give evidence that this vole species plays a crucial role in the maintenance of the parasite's life cycle and that its absence could be a limiting factor for the spread of E. multilocularis in this region.

Detection of Echinococcus multilocularis infection in a colony of cynomolgus monkeys (Macaca fascicularis) using serology and ultrasonography.

Five animals in a colony of cynomolgus monkeys (Macaca fascicularis) died or were euthanatized because of alveolar echinococcosis, during a period of 5 years. The remainder of the colony was screened for possible infection with Echinococcus multilocularis, using serology and ultrasonography. A total of 46 animals out of a group of 55 were examined. The presence of anti-Em2 antibodies analyzed with enzyme-linked immunosorbent assay was demonstrated in 3 monkeys. In 2 of these 3 monkeys, multilocular structures compatible with metacestodal cysts in the liver were identified, using ultrasonography. The presence of alveolar echinococcosis was subsequently confirmed at postmortem examination in 1 animal. The other animals are still alive. Two other monkeys were negative in the serological examination but had cystic structures in the liver, which were identified as bile duct cysts at postmortem examination in 1 animal. The other monkey is still alive. These findings suggest that serology for antibodies against the Em2 antigen may represent a useful method in identifying animals that might be infected with E. multilocularis and are therefore at risk of developing fatal alveolar echinococcosis.

An immunohistochemical study of retinol-binding protein (RBP) in livers of free-living polar bears (Ursus maritimus) from east Greenland.

From 1999 to 2002 samples from 114 free-ranging polar bears (Ursus maritimus) were collected in the municipality of Scoresby Sound, East Greenland, to detect levels of organochlorines and potential histopathologic changes. Livers of 16 female polar bears from this group were evaluated histologically and analyzed for hepatic retinol-binding protein by immunohistochemistry. Retinol-binding protein is the main transport protein for retinol, an important vitamin A metabolite in the polar bear. Only mild pathologic changes were noted on histologic evaluation of the livers. Small lymphocytic or lymphohistiocytic infiltrates were present in all the livers. Small lipid granulomas, mild periportal fibrosis, and bile duct proliferation were found in several cases. Immunohistochemistry for retinol-binding protein of hepatic tissue from free-ranging polar bears showed no distinct difference in staining intensity by a number of criteria: age, season (fasting and nonfasting), or lactation status. The staining was diffuse to finely stippled in the cytoplasm and showed very little variation among the animals. Because of the lack of macroscopic changes and the absence of severe histologic liver lesions, these polar bears were assumed to be healthy. The diffuse cytoplasmic retinol-binding protein staining in hepatocytes of free-ranging polar bears varies markedly from the prominent granular, less intense staining of captive polar bears investigated previously.

Echinococcus multilocularis in a European beaver from Switzerland.

Infection with the larval stage of the cestode parasite Echinococcus multilocularis was diagnosed in a European beaver (Castor fiber) in central Switzerland. The animal was hit, run over by a car, and died of trauma. It was in normal body condition and no signs of disease were seen. At necropsy, multiple cystic structures up to 1 cm in diameter were found in the liver adjacent to the hilus. Within the parasite vesicles, multiple protoscolices were visible. The species was determined to be Echinococcus multilocularis by upon polymerase chain reaction and direct immunofluorescence with MAbG11-FITC. This is the first report of Echinococcus multilocularis in European beaver.

Notoedric and sarcoptic mange in free-ranging lynx from Switzerland.

Between March and December 1999, five free-ranging lynx (Lynx lynx) affected by mange were found dead or shot by game wardens in the Swiss Alps. In the first two cases, Notoedres cati was isolated from the skin; in the third and fourth case, Sarcoptes scabiei was the cause of the infection; and in the fifth case, a mixed infection was diagnosed. Red foxes (Vulpes vulpes) affected with sarcoptic mange and domestic cats infested with N. cati are likely to be the sources of infection. It seems improbable that mange will occur as an epidemic in lynx in Switzerland, but losses due to infections with N. cati and/or S. scabiei may have an impact on this small, geographically limited lynx population. This is the first report of notoedric mange in a free-ranging lynx and the first report of mange in lynx from Switzerland.

Causes of mortality in reintroduced Eurasian lynx in Switzerland.

Seventy-two lynx, found dead in the Swiss Alps and the Jura Mountains (Switzerland) from 1987-99, were evaluated to determine the cause of death. Seventy-two per cent (52/72) of all animals died because of noninfectious diseases or causes such as vehicular collision and poaching. Eighteen percent (13/72) died from infectious diseases, including some which could have been transferred to the lynx from domestic animals or other wild animals such as panleukopenia and sarcoptic mange. If only radio-tagged animals (included in a monitoring program) were taken into consideration, the percentage of mortality caused by infectious diseases rose to 40%, indicating that infections might be underestimated in randomly found mortality events. We hypothesize that even a few cases of infections in a small population like the lynx, which are additionally threatened by noninfectious causes, may threaten the long term survival of the population.