Wild boars as possible source of hemorrhagic leptospirosis in Berlin, Germany

Leptospira in Slaughtered Fattening Pigs in Southern Italy: Serological Survey and Molecular Typing

Simple Summary

In this study, serological and molecular assays in 55 pigs in Sicily were conducted in order to investigate Leptospira spp. prevalence and to carry out strain characterization. A seropositivity rate of 16.4% was determined; 3.64% of kidney samples tested positive for pathogenic Leptospiral DNA. Obtained data showed that Leptospira infection is common among pigs in southern Italy, confirming the importance of Leptospiral infection in pigs and reaffirming the potential role of these animals as a source of infection for humans (occupational risk) and other animals. Our study delivers a comprehensive overview based on up-to-date data to deepen the knowledge of swine leptospiral infections, characterize new potential emerging strains, and reinforce control measures able to reduce the infection risk in swine herds.

Abstract

Leptospirosis is a re-emerging zoonosis of worldwide significance; a wide spectrum of wild and domestic animal species act as natural or accidental hosts. Swine can act as maintenance or accidental hosts of pathogenic Leptospira spp. This study aimed at investigation of Leptospira spp. prevalence and diversity in slaughtered pigs in southern Italy (Sicily). In total, 55 samples of kidneys and blood were collected. Microscopic agglutination test and real-time PCR were performed to detect pathogenic and intermediately pathogenic Leptospira. Partial rpoB gene sequencing and multi-locus sequence typing (MLST) were performed to characterize Leptospira species. The analysis showed a seropositivity rate of 16.4%, with Australis representing the most frequently identified serogroup (63.64%); Pomona and Sejroe were detected with a prevalence of 27.27% and 9.09%, respectively. Pathogenic Leptospiral DNA was detected in 2 kidney samples (3.64%). Leptospira were identified through MLST as L. borgpetersenii serovar Tarassovi (serogroup Tarassovi). Obtained data confirmed the presence of Leptospira infection among pigs in southern Italy, suggesting that management of these animals may be considered an occupational risk for humans.

Leptospira Survey in Wild Boar (Sus scrofa) Hunted in Tuscany, Central Italy

Leptospirosis is a re-emerging, worldwide zoonosis, and wild boar (Sus scrofa) are involved in its epidemiology as the reservoir. The aim of this study was to investigate the prevalence of Leptospira with serological, bacteriological, and molecular assays in wild boar hunted in Tuscany (Italy) during two hunting seasons. In total, 287 specimens of sera, kidneys, and liver were collected to perform microscopic agglutination tests (MATs), isolation, and RealTime PCR to detect pathogenic (lipL32 gene), intermediate (16S rRNA gene), and saprophytic (23S rRNA gene) Leptospira. Within sera, 39 (13.59%) were positive to the MAT, and Australis was the most represented serogroup (4.88%), followed by Pomona (4.18%), and Tarassovi (3.14%). Moreover, four Leptospira cultures were positive, and once isolates were identified, one was identified as L. borgpetersenii serovar Tarassovi, and three as L. interrogans serovar Bratislava. Pathogenic Leptospira DNA were detected in 32 wild boar kidneys (11.15%). The characterization through the amplification of the rrs2 gene highlighted their belonging to L. interrogans (23 kidneys), L. borgpetersenii (four), and L. kirschneri (one), while nine kidneys (3.14%) were positive for intermediate Leptospira, all belonging to L. fainei. The results of this study confirmed the importance of wild boar in the epidemiology of leptospirosis among wildlife in Central Italy.

Molecular detection of Leptospira spp. in wild boar (Sus scrofa) hunted in Liguria region (Italy)

Leptospirosis is a re-emerging and widespread zoonosis, worldwide distributed, due to a wide variety of wild and domestic animal species able to act as natural or accidental hosts. During last years, in Europe, as in Italy, wild boar (Sus scrofa) population is increased. This animal represents a reservoir for different etiological agents, such as Leptospira. The aim of this investigation was to evaluate the prevalence of Leptospira spp. in wild boar hunted in Liguria region (Italy) during two-year hunting seasons. From 611 hunted wild boar, kidneys were collected. DNA was extracted from each organ and different targets were used to detect pathogenic (lipL32 gene), intermediate (16S rRNA gene) and saprophytic (23S rRNA gene) Leptospira by Taqman-based RealTime-PCR assays. Overall, kidneys were sampled from 282 adults, 155 sub-adults and 174 young wild boar (in total 314 males and 298 females). By RealTime PCR 77 kidneys were positive and, among these, 74 resulted positive for pathogenic (96.10%) and 3 (3.90%) for intermediate Leptospira. No significant differences in pathogenic Leptospira infection ratio were detected between male (11.50%) and female (12.75%). Only 13 sub-adult animals (8.39%) resulted infected by pathogenic Leptospira; 23 young animals (13.22%) and 38 adult animals (13.47%) were positive. The results of this study confirmed the importance of wild boar in the epidemiology of leptospirosis, which is able to infect other animal species (domestic and wild) including humans. Rarely, intermediate Leptospira could be able to infect wild boar with a renal localization that can contribute to their shedding and circulation.

Leptospira reservoirs among wildlife in Brazil: Beyond rodents

Leptospirosis is a disease of great importance in tropical regions. Infection occurs mainly through contact with water contaminated with the urine of infected animals, especially that of rodents. Despite the diversity and abundance of wild fauna in Brazil, little is known about the role of other wild species in the epidemiology of leptospirosis. This study aimed to investigate new reservoirs of Leptospira among wildlife in Brazil, using serological and molecular diagnoses in a large-sized sample. Biological samples were collected from 309 free-ranging mammals, belonging to 16 species. The majority of the animals included were opossums (Didelphis albiventris) and coatis (Nasua nasua). Blood and urine samples were subjected to the microscopic agglutination test (MAT) and real-time PCR, respectively. Genetic characterization of genomospecies was performed using PCR amplicons. Statistical analysis was applied to test associations between positive diagnoses and age, sex, season and type of environment. The prevalence of infection found via MAT and PCR was 11% and 5.5%, respectively. If these tests are taken to be complementary, the overall prevalence was 16%. The most common serogroups were Djasiman and Australis, while L. santarosai was the prevalent genomospecies. Significant differences in prevalence between animal species were observed. Greater risk of infection was detected among adult opossums than among young ones. The influence of each serogroup and genomospecies was tested for the same variables, and this revealed higher risk of infection by L. santarosai among male opossums than among females. The present study highlights the exposure and carrier status of several wild species in Brazil and it indicates that coatis and other carnivores are priorities for further investigations.

A Review of the Current Status of Relevant Zoonotic Pathogens in Wild Swine (Sus scrofa) Populations: Changes Modulating the Risk of Transmission to Humans

Many wild swine populations in different parts of the World have experienced an unprecedented demographic explosion that may result in increased exposure of humans to wild swine zoonotic pathogens. Interactions between humans and wild swine leading to pathogen transmission could come from different ways, being hunters and game professionals the most exposed to acquiring infections from wild swine. However, increasing human settlements in semi-natural areas, outdoor activities, socio-economic changes and food habits may increase the rate of exposure to wild swine zoonotic pathogens and to potentially emerging pathogens from wild swine. Frequent and increasing contact rate between humans and wild swine points to an increasing chance of zoonotic pathogens arising from wild swine to be transmitted to humans. Whether this frequent contact could lead to new zoonotic pathogens emerging from wild swine to cause human epidemics or emerging disease outbreaks is difficult to predict, and assessment should be based on thorough epidemiologic surveillance. Additionally, several gaps in knowledge on wild swine global population dynamics trends and wild swine-zoonotic pathogen interactions should be addressed to correctly assess the potential role of wild swine in the emergence of diseases in humans. In this work, viruses such as hepatitis E virus, Japanese encephalitis virus, Influenza virus and Nipah virus, and bacteria such as Salmonella spp., Shiga toxin-producing Escherichia coli, Campylobacter spp. and Leptospira spp. have been identified as the most prone to be transmitted from wild swine to humans on the basis of geographic spread in wild swine populations worldwide, pathogen circulation rates in wild swine populations, wild swine population trends in endemic areas, susceptibility of humans to infection, transmissibility from wild swine to humans and existing evidence of wild swine-human transmission events.

Leptospirosis in Hawaii, USA, 1999-2008

Although infrequently diagnosed in the United States, leptospirosis is a notable reemerging infectious disease throughout developing countries. Until 1995, when the disease was eliminated from the US list of nationally notifiable diseases, Hawaii led the nation in reported annual incidence rates. Leptospirosis remains a notifiable disease in Hawaii. To ascertain the status of leptospirosis in Hawaii since the most recent US report in 2002, we reviewed 1999–2008 data obtained from case investigation reports by the Hawaii State Department of Health. Of the 345 case reports related to in-state exposures, 198 (57%) were laboratory confirmed. Our findings indicate a change in seasonal disease occurrence from summer to winter and in the infective serogroup from Icterohemorrhagiae to Australis. Also, during the past 20 years, recreational exposures have plateaued, while occupational exposures have increased. Ongoing surveillance is needed to clarify and track the dynamic epidemiology of this widespread zoonosis.

Detection of hepatitis E virus in wild boars of rural and urban regions in Germany and whole genome characterization of an endemic strain

Background

Hepatitis E is an increasingly diagnosed human disease in Central Europe. Besides domestic pigs, in which hepatitis E virus (HEV) infection is highly prevalent, wild boars have been identified as a possible source of human infection. In order to assess the distribution of HEV in the wild boar population of Germany, we tested liver samples originating from different geographical regions for the presence of the HEV genome and compared the detected sequences to animal and human HEV strains.

Results

A total of 148 wild boar liver samples were tested using real-time RT-PCR resulting in an average HEV detection rate of 14.9% (95% CI 9.6–21.6). HEV was detected in all age classes and all geographical regions. However, the prevalence of HEV infection was significantly higher in rural as compared to urban regions (p < 0.001). Sequencing of the PCR products indicated a high degree of heterogenicity of the detected viruses within genotype 3 and a grouping according to their geographical origin. The whole genome sequence of an HEV isolate (wbGER27) detected in many wild boars in the federal state of Brandenburg was determined. It belongs to genotype 3i and shows 97.9% nucleotide sequence identity to a partial sequence derived from a human hepatitis E patient from Germany.

Conclusion

The results indicate that wild boars have to be considered as a reservoir for HEV in Germany and that a risk of HEV transmission to humans is present in rural as well as urban regions.

Leptospirosis in urban wild boars, Berlin, Germany

We found antibodies to leptospires in 25 (18%) of 141 wild boars from Berlin (95% confidence interval 12–25). Seropositivity was associated with chronic interstitial nephritis (odds ratio 10.5; p = 0.01), and leptospires were detected in kidney tissues. Wild boars represent a potential source for human leptospirosis in urban environments.