the outbreak occurred at a large , indoor , 5,000-sow farm in the poltava region of ukraine where 240 sows per week were kept to give birth , which is referred to as farrowing on porcine farms . clinical signs were first seen in a farrowing sow that was vomiting and had profuse diarrhea 10 days postfarrowing . within hours disease was most severe among piglets < 10 days of age ; the case - fatality rate reached nearly 100% . the decision was made to euthanize piglets < 10 days of age during a 3-week period from the start of the outbreak . disease was less severe in adults , whose appetite returned and diarrhea ceased within 3 days . abortions occurred immediately following the outbreak in 38% of 1 batch of sows that were at 2835 days gestation ; no diagnostic investigation was made to determine the cause . it was not established whether they were a result of the ped outbreak or control methods such as  back - feeding  fecal material to piglets . abortions did not occur in other groups of sows and have not been reported as a feature of ped outbreaks in north america . the reproductive status of sows at other stages of gestation was not substantially affected by the initial ped outbreak , and no higher return rate was observed . postpartum sows did not fail to produce milk , but those affected by pedv had a reduced feed intake and associated reduced milk output . the performance of the pig unit took 20 weeks to return to preoutbreak levels . during that time , a total of 30,000 piglets died , which equates to a loss of 6 weaned piglets per sow per year . lactogenic immunity enhancement was initiated by deliberate reexposure of pregnant sows to infected piglet feces 6 weeks before farrowing . the environmental viral load was reduced by cleaning and disinfection of the area , euthanizing of neonatal piglets , and reduction of transmission by humans and other vectors through enhanced internal biosecurity . we tested them onsite using a lateral flow device , antigen rapid ped / tge ag test kit ( bionote , hwasung - si , korea ) , which indicated the presence of pedv antigen in the feces . we confirmed these findings at the uk animal and plant health agency using an in - house pedv pcr and a commercially available pedv / transmissible gastroenteritis virus quantitative reverse transcription - pcr kit ( qiagen , hilden , germany ) . a blast search ( http://blast.ncbi.nlm.nih.gov/blast.cgi ) of the 160-nt pcr amplicon revealed the highest similarity ( 99% ) to pedv strains from the united states and china . pedv rna was then subjected to deoxyribonuclease i digestion and converted to cdna for preparation of sequencing libraries by using a nextera xt kit ( illumina , san diego , ca , usa ) . the consensus sequence was obtained by de novo assembly by using the velvet 1.2.10 algorithm ( 12 ) of the sequence reads that mapped to the reference strain ( genbank accession no . nucleotide analyses of the full genome of the virus showed the highest similarity to pedv strains reported in 2013 from the united states ; specifically , strains usa / kansas29/2013 ( genbank accession no . the nucleotide identity was substantially lower ( 98.5% ) when compared to those of the 2014 strains isolated in germany , which are similar to another strain isolated in north america , ohio851/2013 ( 8) . accordingly , the ukraine virus clustered phylogenetically with pedv strains from north america in genetic clade ii ( 6 ) but was distinct from strains currently and previously found elsewhere in europe , such as the prototype pedv strain cv777 , with which it shares only 96.5% homology ( figure ) . however , the genetic analysis does not , at this stage , support drawing conclusions regarding the relative pathogenicity of this apparently virulent pedv strain , similar to past instances of pedv in europe , of which very few have been characterized ; parallel experimental infection of pigs would be required for further investigation . phylogenetic analysis of the full - length genome of the porcine epidemic diarrhea virus ( pedv ) ukraine / poltava01/2014 ( bold text ) . the full - length genomes of pedv were aligned by using the megalign software of the dnastar lasergene core suite ( dnastar , inc . , madison , wi , usa ) and phylogenetic analysis was done by using mega 5.2 software ( 13 ) . the tree was constructed by using the neighbor - joining method and 1,000 bootstrap replications . each virus on the tree is represented by accession number , strain , and year of sample collection . ukraine / poltava01/2014 clusters in close proximity to recent strains in the united states other than the ohio851 variant , and both are substantially genetically different from the previous european variants , such as the prototype strain cv777 , which is embedded in another cluster . the farm was found to be free from mycoplasma hyopneumoniae , brachyspira hyodysenteriae , mange , toxigenic pasteurella multocida , porcine reproductive and respiratory syndrome virus , transmissible gastroenteritis virus , aujeszky s disease virus , and classical and african swine fever viruses . persons on the farm practiced strict biosecurity measures to maintain a specific pathogen free status . no breach in biosecurity could be identified after a review of potential pedv introduction routes involving pigs or humans or vehicles , equipment , and other fomites ; the source of infection remains unknown . however , there were reports of a ped - affected pig farm 1.5 km from this unit , and the potential for unidentified fomite or other transmission from this herd , or another undisclosed infected herd , therefore existed . windborne transmission has been suggested to explain some outbreaks in the united states ( 14 ) and is another possibility to consider in this case . this ped outbreak in ukraine showed clinical characteristics similar to outbreaks caused by virulent strains of pedv reported from north america ( 4 ) . the virus clusters phylogenetically with viruses from recent outbreaks in the united states and mexico ( 6 ) . the presence of such a pedv strain in ukraine highlights the threat to neighboring countries and those in the european union where pedv has not been detected ( e.g. , scandinavia ) or has not caused disease in recent decades ( e.g. , the united kingdom ) and where pig herds are considered largely naive to pedv . furthermore , pig farming has changed over recent decades , and the establishment of more large holdings would produce more virus following introduction of pedv .   this outbreak emphasizes the need for decision - makers of countries , pig farms , and allied industries to implement and maintain biosecurity measures to minimize the risk for spread of pedv to new areas . early detection of suspected clinical signs on pig farms and , when these occur , prompt testing for pedv by pcr are also vital ( 15 ) . a coordinated approach is essential to prevent introduction of pedv , promote early detection should introduction occur , control disease , and minimize spread of infection . references for outbreaks of porcine epidemic diarrhea virus in 3 countries in the americas during 2014 .
an outbreak of porcine epidemic diarrhea occurred in the summer of 2014 in ukraine , severely affecting piglets < 10 days of age ; the mortality rate approached 100% . 
 full genome sequencing showed the virus to be closely related to strains reported from north america , showing a sequence identity of up to 99.8% .