Trichinella infection in Serbia from 2011 to 2020: a success story in the field of One Health.

In Serbia, modern pork production systems with implemented control measures, including the detection of Trichinella larvae in meat (ISO18743), have eliminated farmed pork from pigs slaughtered at abattoirs as a source of trichinellosis. Epidemiological data from 2011 to 2020 indicate that the number of human cases and the number of infected domestic pigs has decreased significantly. Over the years, pork was the most frequent source of human infection. Cases generally occurred in small family outbreaks, and the infection was linked to consumption of raw or undercooked pork from backyard pigs. In most of the outbreaks, T. spiralis was the aetiological agent of infection, but in 2016, a large outbreak was caused by consumption of uninspected wild boar meat containing T. britovi larvae. To achieve safe pork, it is important that consumers of pork from animals raised in backyard smallholdings and of wild game meat are properly educated about the risks associated with consumption of untested meat. Laboratories conducting Trichinella testing should have a functional quality assurance system to ensure competency of analysts and that accurate and repeatable results are achieved. Regular participation in proficiency testing is needed.

Methodology and results of integrated WNV surveillance programmes in Serbia.

Studies conducted during the past few years have confirmed active West Nile virus (WNV) circulation in Serbia. Based on these studies and the epidemiological situation, the Veterinary Directorate of the Ministry of Agriculture and Environmental Protection launched national WNV surveillance programmes in 2014 and 2015. The programmes encompassed the territory of Serbia and were conducted by the veterinary service in collaboration with entomologists and ornithologists. The objective of the programmes was early detection of WNV and timely reporting to the public health service and local authorities to increase both clinical and mosquito control preparedness. The WNV surveillance programmes were based on direct and indirect surveillance of the presence of WNV by the serological testing of initially seronegative sentinel horses and chickens as well as through viral detection in pooled mosquito and wild bird samples. The most intense WNV circulation was observed in all seven districts of Vojvodina Province (northern Serbia) and Belgrade City, where most of the positive samples were detected among sentinel animals, mosquitoes and wild birds. The West Nile virus surveillance programmes in 2014 and 2015 showed satisfactory results in their capacity to indicate the spatial distribution of the risk for humans and their sensitivity to early detect viral circulation at the enzootic level. Most of the human cases were preceded by the detection of WNV circulation as part of the surveillance programmes. According to the existing data, it can be reasonably assumed that WNV infection, now an endemic infection in Serbia, will continue to present a significant problem for the veterinary service and public health.

West Nile virus 'circulation' in Vojvodina, Serbia: Mosquito, bird, horse and human surveillance.

Efforts to detect West Nile virus (WNV) in the Vojvodina province, northern Serbia, commenced with human and mosquito surveillance in 2005, followed by horse (2009) and wild bird (2012) surveillance. The knowledge obtained regarding WNV circulation, combined with the need for timely detection of virus activity and risk assessment resulted in the implementation of a national surveillance programme integrating mosquito, horse and bird surveillance in 2014. From 2013, the system showed highly satisfactory results in terms of area specificity (the capacity to indicate the spatial distribution of the risk for human cases of West Nile neuroinvasive disease - WNND) and sensitivity to detect virus circulation even at the enzootic level. A small number (n = 50) of Culex pipiens (pipiens and molestus biotypes, and their hybrids) females analysed per trap/night, combined with a high number of specimens in the sample, provided variable results in the early detection capacity at different administrative levels (NUTS2 versus NUTS3). The clustering of infected mosquitoes, horses, birds and human cases of WNND in 2014-2015 was highly significant, following the south-west to north-east direction in Vojvodina (NUTS2 administrative level). Human WNND cases grouped closest with infected mosquitoes in 2014, and with wild birds/mosquitoes in 2015. In 2014, sentinel horses showed better spatial correspondence with human WNND cases than sentinel chickens. Strong correlations were observed between the vector index values and the incidence of human WNND cases recorded at the NUTS2 and NUTS3 levels. From 2010, West Nile virus was detected in mosquitoes sampled at 43 different trap stations across Vojvodina. At 14 stations (32.56%), WNV was detected in two different (consecutive or alternate) years, at 2 stations in 3 different years, and in 1 station during 5 different years. Based on these results, integrated surveillance will be progressively improved to allow evidence-based adoption of preventive public health and mosquito control measures.

Oral vaccination of backyard pigs against classical swine fever.

Vaccination represents a key pillar of most classical swine fever (CSF) control programmes. In backyard production systems the systematic implementation of parenteral vaccination proves to be difficult and alternative delivery mechanisms might be needed. In this study the use of oral vaccination against CSF in backyard pigs was tested under field conditions. The main objective was to assess uptake efficacy and immune response after oral vaccination of backyard pigs with bait vaccine currently used in the European Union for CSF control in wild boar (RIEMSER(®) Schweinepestoralvakzine). In total 85 backyard pigs belonging to 16 holdings were vaccinated orally by distributing four baits per pig, given on two consecutive days. The baits were distributed on pen floors. 73% of the pigs older than 12 weeks (n=41) had protective antibody titres 28 days after oral vaccination. The seroconversion rate in young piglets (n=44, younger than 12 weeks) was 64%. Based on the results obtained we concluded that in an endemic situation where usual control measures (stamping out, zoning with restrictive measures, parenteral vaccination, etc.) may prove to be insufficient, a systematic vaccination based on the use of oral vaccine can be an appropriate tool for an improved CSF control in backyard production systems.

Molecular characterisation of rabies virus strains in the Republic of Macedonia.

Rabies, a worldwide zoonosis, remains a public-health concern despite oral wildlife vaccination in Europe. After a ten-year break, Macedonia reported eight rabies cases in 2011-2012. Two countries (Serbia and Bulgaria) bordering Macedonia are reporting cases in domestic and wild animals. This report describes the genetic characterisation of eight isolates from Macedonia compared with representative samples from neighbouring countries. All of the isolates tested belong to the Eastern European group, with a high degree of nucleotide sequence identity in the nucleoprotein gene. The close genetic relationship between isolates from the three bordering countries suggests that wildlife is responsible for rabies movements in the region.