Jesús M. Cuesta

Severity of bovine tuberculosis is associated with co-infection with common pathogens in wild boar

Co-infections with parasites or viruses drive tuberculosis dynamics in humans, but little is known about their effects in other non-human hosts. This work aims to investigate the relationship between Mycobacterium bovis infection and other pathogens in wild boar (Sus scrofa), a recognized reservoir of bovine tuberculosis (bTB) in Mediterranean ecosystems. For this purpose, it has been assessed whether contacts with common concomitant pathogens are associated with the development of severe bTB lesions in 165 wild boar from mid-western Spain. The presence of bTB lesions affecting only one anatomic location (cervical lymph nodes), or more severe patterns affecting more than one location (mainly cervical lymph nodes and lungs), was assessed in infected animals. In addition, the existence of contacts with other pathogens such as porcine circovirus type 2 (PCV2), Aujeszkys disease virus (ADV), swine influenza virus, porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae, Haemophilus parasuis and Metastrongylus spp, was evaluated by means of serological, microbiological and parasitological techniques. The existence of contacts with a structured community of pathogens in wild boar infected by M. bovis was statistically investigated by null models. Association between this community of pathogens and bTB severity was examined using a Partial Least Squares regression approach. Results showed that adult wild boar infected by M. bovis had contacted with some specific, non-random pathogen combinations. Contact with PCV2, ADV and infection by Metastrongylus spp, was positively correlated to tuberculosis severity. Therefore, measures against these concomitant pathogens such as vaccination or deworming, might be useful in tuberculosis control programmes in the wild boar. However, given the unexpected consequences of altering any community of organisms, further research should evaluate the impact of such measures under controlled conditions. Furthermore, more research including other important pathogens, such as gastro-intestinal nematodes, will be necessary to complete this picture.

Reducing Eurasian wild boar (Sus scrofa) population density as a measure for bovine tuberculosis control: effects in wild boar and a sympatric fallow deer (Dama dama) population in Central Spain.

Research on management of bovine tuberculosis (bTB) in wildlife reservoir hosts is crucial for the implementation of effective disease control measures and the generation of practical bTB management recommendations. Among the management methods carried out on wild species to reduce bTB prevalence, the control of population density has been frequently used, with hunting pressure a practical strategy to reduce bTB prevalence. However, despite the number of articles about population density control in different bTB wildlife reservoirs, there is little information regarding the application of such measures on the Eurasian wild boar (Sus scrofa), which is considered the main bTB wildlife reservoir within Mediterranean ecosystems. This study shows the effects of a management measure leading to a radical decrease in wild boar population density at a large hunting estate in Central Spain, in order to assess the evolution of bTB prevalence in both the wild boar population and the sympatric fallow deer population. The evolution of bTB prevalence was monitored in populations of the two wild ungulate species over a 5-year study period (2007-2012). The results showed that bTB prevalence decreased in fallow deer, corresponding to an important reduction in the wild boar population. However, this decrease was not homogeneous: in the last season of study there was an increase in bTB-infected male animals. Moreover, bTB prevalence remained high in the remnant wild boar population.

Influence of Porcine Circovirus Type 2 Infections on Bovine Tuberculosis in Wild Boar Populations

The wild boar is an important reservoir of bovine tuberculosis (bTB) in south-western Spain. Some risk factors such as wild boar density or age have been associated with the presence of high prevalences of bTB in wild boar. However, the influence of other risk factors such as co-infections with other pathogens has not yet been studied. This work aims to assess the influence of porcine circovirus type 2 (PCV-2) infection on bTB prevalence and bTB lesional patterns observed in wild boar. The presence of bTB-like lesions was evaluated in 551 hunted wild boar from 11 different game estates in south-western Spain, with a known history of bTB. Tuberculosis prevalences in each estate were calculated based on the percentage of animals found with bTB-like lesions. The percentage of animals with generalized bTB lesional patterns (bTB lesions in more than one organ) was also assessed. The prevalence of PCV-2 was studied in each estate using a specific PCR assay. The relationship between PCV-2 and bTB prevalences and between PCV-2 infections and the presence of generalized lesional patterns in wild boar were analysed. A statistical relationship between the prevalences of bTB and PCV-2 was found, with bTB prevalences being higher in estates where prevalences of PCV-2 were high. On the other hand, animals infected with PCV-2 were more likely to develop a generalized lesional pattern. Porcine circovirus type 2 prevalences seem to be associated with prevalences of bTB in wild boar. PCV-2 infection may aggravate the development and severity of bTB, favouring the presence of generalized lesional patterns and raising the risk of contagion in these estates. The implementation of sanitary measures that focus on the control of PCV-2 infection may be necessary as a preliminary measure in bTB control programmes for wild boar.

Helcococcus ovis isolated from a goat with purulent bronchopneumonia and pulmonary abscesses.

The current study describes the recovery of Helcococcus ovis from an adult female Verata breed goat that was euthanized because of respiratory problems and emaciation. At necropsy, the affected animal showed a purulent bronchopneumonia with scattered pulmonary abscesses and fibrous pleural adhesions. A Gram-positive, catalase-negative, coccus-shaped bacterium was isolated from the lung tissue and confirmed as H. ovis by 16S ribosomal RNA gene sequencing.

OCULAR LESIONS ASSOCIATED WITH CHLAMYDIA SUIS IN A WILD BOAR PIGLET (SUS SCROFA) FROM A SEMI-FREE RANGE POPULATION IN SPAIN

Abstract:  The role of the wild boar (Sus scrofa) as a reservoir for a large number of pathogens that can affect both domestic animals and humans has been widely studied in the last few years. However, the impact of some of these pathogens on the health of wild boar populations is still being determined. This article presents a clinical case of severe bilateral keratoconjunctivitis affecting a 2-mo-old piglet from a semi–free range population in Spain. Histopathologic and microbiologic analysis revealed lesions in the cornea, choroid, and optical nerve, and Chlamydia suis was detected in the eyes bilaterally. The visual handicap resulting from this type of lesion greatly affects the survival of this affected piglet.

Fatal outbreak of systemic pasteurellosis in a wild boar (Sus scrofa) population from southwest Spain.

Pasteurella multocida is a common pathogen of swine that causes specific diseases with great economic impact. However, the importance of this pathogen in wild boar is still unknown. In the current work, an outbreak of systemic pasteurellosis in wild boar with a high mortality rate is described. A total of 23 wild boar of all ages were found dead over a 5-day period on a game estate in southwest Spain (11.11% mortality). Three animals were necropsied and showed subcutaneous edema, a generalized congestion, and fibrin deposits in the peritoneal cavity. Hemorrhages, general congestion, and intravascular thrombosis were microscopically observed. Pasteurella multocida type B was isolated from all of the studied organs. Outbreaks of systemic pasteurellosis have been described in domestic pigs from Asia and Australia, but not to date in Europe. This outbreak suggests that systemic pasteurellosis affecting wild boar populations may be an important cause of mortality.

FATAL CASE OF STREPTOCOCCUS SUIS INFECTION IN A YOUNG WILD BOAR (SUS SCROFA) FROM SOUTHWESTERN SPAIN

Streptococcus suis is a recognized pathogen that may cause important diseases in pigs and humans. This microorganism has been repeatedly isolated from wild boar (Sus scrofa). However, its health implications for this wild species are still unknown. This article reports a detailed description of a fatal case of septicemia by S. suis affecting a young wild boar. The affected animal, about 15 days old, was found near death and exhibiting neurologic signs at a wild boar estate in southwestern Spain. Postmortem examination showed generalized congestion, brain hemorrhages and lobular pneumonia. Histopathological evaluation demonstrated the presence of meningitis and encephalitis with marked congestion and suppurative bronchopneumonia. Streptococcus suis serotype 2 isolates exhibiting important virulence factors (extracellular factor, muramidase-released protein, and suylisin) were isolated from the affected animal. This study confirms the presence of potentially virulent and zoonotic strains of S. suis in wild boar from Spain.

Pathological observations of porcine respiratory disease complex (PRDC) in the wild boar (Sus scrofa)

Porcine respiratory disease complex (PRDC) is a multifactorial respiratory syndrome related to the infection with different pathogens. Although most of these pathogens have been detected in the wild boar, the PRDC pneumonic lesions in this species have not been characterized. The aims of this study were to assess the presence of the main swine respiratory pathogens in wild boar populations from mid-western Spain and to describe the pathological features present in the lung from animals infected with PRDC pathogens. A pathological assessment based on five histological parameters was carried out in lung sections from 210 hunted wild boar. The presence of Mycoplasma hyopneumoniae, Haemophilus parasuis, Actinobacillus pleuropneumoniae, Pasteurella multocida, Aujeszky’s disease virus, and porcine circovirus type 2 (PCV2) in lungs was assessed by the use of specific PCR assays. Additionally, immunohistochemical techniques were carried out to detect swine influenza virus (SIV) and porcine reproductive and respiratory syndrome virus (PRRSV) infection in the lungs. Furthermore, the distribution of infected cells with PCV2 and the presence of M. hyopneumoniae throughout the pulmonary parenchyma were evaluated using immunohistochemistry and in situ hybridization assays in a subset of animals. Wild boar infected with M. hyopneumoniae, H. parasuis, or P. multocida showed the most severe lesions. M. hyopneumoniae, SIV, PCV2, and PRRSV were detected in single or mixed infections. Animals suffering from mixed infections with M. hyopneumoniae together with different viruses showed severe bronchopneumonia associated with interstitial pneumonia, suggesting that interactions between pathogens might increase the severity of pathological outcomes.

ISOLATION OF AEROMONAS HYDROPHILA IN THE RESPIRATORY TRACT OF WILD BOAR: PATHOLOGIC IMPLICATIONS

Aeromonas hydrophila has been repeatedly reported as an animal pathogen. This study describes a case of a wild boar piglet in Spain with severe purulent pneumonia caused by A. hydrophila. To confirm the presence of A. hydrophila in the respiratory tract of wild boars from the same region, lung samples from 34 adult hunted animals and nasal samples from 12 live animals were collected and cultured in selective medium. Lung lesions were studied in hunted wild boars to determine the presence of A. hydrophila and to assess its role as a possible respiratory pathogen in wild boars. A. hydrophila was isolated in 10.87% of the animals studied (8.82% of the dead animals and 16% of the live animals). However, its presence in the lungs of adults could not be correlated with the lesions found. Thus, the role of A. hydrophila as a respiratory pathogen is likely to be influenced by other factors, such as age, immunologic status, or coinfection with other pathogens. As a zoonotic pathogen, the presence of A. hydrophila in wild boars may pose a potential risk to people who consume their flesh.