Japanese Swine Research Articles

Characteristics of antimicrobial residues in manure composts from swine farms: Residual patterns, removal efficiencies, and relation to purchased quantities and composting methods in Japan

Present study provides first comprehensive results on the residual levels of 19 antimicrobial (AM) residues in 12 Japanese swine manure composting facilities that use open or enclosed types of treatment methods. Tilmicosin (14000 μg/kg d.w.) and tiamulin (15000 μg/kg d.w.) were present in the highest concentrations in manure composts. Morantel (MRT) had the highest detection frequency (100%) in compost, suggesting its ubiquitous usage and resistance to degradation during composting. Sulfamethoxazole had low detection frequencies and concentrations, likely due to limited partitioning to the solid phase. A positive correlation (p < 0.05) between purchasing quantities and residue levels in manure composts was detected for fluoroquinolones (FQs). The removal efficiencies of AMs in enclosed-type facilities were lower and more inconsistent than those in open-type facilities. Tetracyclines (TCs), lincomycin, and trimethoprim were easily removed from open-type facilities, whereas FQs and MRT persisted in both facilities. After discontinuing the usage of oxytetracycline (OTC), TCs concentrations reduced drastically in input materials, remained pseudo-persistent in composts for up to 4 months, suggesting a time lag for composting and were not detected (<10 µg/kg) after 4 months of OTC withdrawal. This study emphasizes on the effectiveness of manure composting methods in reducing AM residues in swine waste.

Genetic Characterization of Influenza A Viruses in Japanese Swine in 2015 to 2019.

To assess the current status of influenza A viruses of swine (IAVs-S) throughout Japan and to investigate how these viruses persisted and evolve on pig farms, we genetically characterized IAVs-S isolated during 2015 to 2019. Nasal swab samples collected through active surveillance and lung tissue samples collected for diagnosis yielded 424 IAVs-S, comprising 78 H1N1, 331 H1N2, and 15 H3N2 viruses, from farms in 21 sampled prefectures in Japan. Phylogenetic analyses of surface genes revealed that the 1A.1 classical swine H1 lineage has evolved uniquely since the late 1970s among pig populations in Japan. During 2015 to 2019, A(H1N1)pdm09 viruses repeatedly became introduced into farms and reassorted with endemic H1N2 and H3N2 IAVs-S. H3N2 IAVs-S isolated during 2015 to 2019 formed a clade that originated from 1999-2000 human seasonal influenza viruses; this situation differs from previous reports, in which H3N2 IAVs-S derived from human seasonal influenza viruses were transmitted sporadically from humans to swine but then disappeared without becoming established within the pig population. At farms where IAVs-S were frequently isolated for at least 3 years, multiple introductions of IAVs-S with phylogenetically distinct hemagglutinin (HA) genes occurred. In addition, at one farm, IAVs-S derived from a single introduction persisted for at least 3 years and carried no mutations at the deduced antigenic sites of the hemagglutinin protein, except for one at the antigenic site (Sa). Our results extend our understanding regarding the status of IAVs-S currently circulating in Japan and how they genetically evolve at the farm level.IMPORTANCE Understanding the current status of influenza A viruses of swine (IAVs-S) and their evolution at the farm level is important for controlling these pathogens. Efforts to monitor IAVs-S during 2015 to 2019 yielded H1N1, H1N2, and H3N2 viruses. H1 genes in Japanese swine formed a unique clade in the classical swine H1 lineage of 1A.1, and H3 genes originating from 1999-2000 human seasonal influenza viruses appear to have become established among Japanese swine. A(H1N1)pdm09-derived H1 genes became introduced repeatedly and reassorted with endemic IAVs-S, resulting in various combinations of surface and internal genes among pig populations in Japan. At the farm level, multiple introductions of IAVs-S with phylogenetically distinct HA sequences occurred, or IAVs-S derived from a single introduction have persisted for at least 3 years with only a single mutation at the antigenic site of the HA protein. Continued monitoring of IAVs-S is necessary to update and maximize control strategies.

Comparative genomics and phylogenetic analysis of Bacillus anthracis strains isolated from domestic animals in Japan

Anthrax, caused by Bacillus anthracis, is a severe zoonosis with a great impact on both human and animal health. In the present study, we identified the phylogenetic relationships among 16 Japanese strains of B. anthracis, including eight bovine strains, two equine strains, five swine strains, and one former vaccine strain, using in silico canonical single nucleotide polymorphism (canSNP) and core genome SNP analyses. The results of our in silico canSNP analysis suggest that these 16 Japanese strains could be divided into four lineages: i) one equine strain in A.Br.Ames, ii) one equine and six bovine strains in A.Br.001/002, iii) five swine and one bovine strain in A.Br.Aust94, and iv) one bovine and one vaccine strain in A.Br.008/011. A comparison with non-Japanese B. anthracis strains revealed a total of 3787 SNPs identified from the whole genome sequences of the Japanese strains; these SNP data were subjected to a phylogenetic analysis using the maximum parsimony (MP) method. Our core genome SNP analysis was also able to detect differences of a few chromosomal SNPs across clonal strains from the same cases that had different storage and passage histories.Additionally, our whole genome SNP analysis clearly indicated that the Japanese swine anthrax cases of 1982 were caused by at least three independent strains; however, their phylogeny revealed no clear relationship with swine strains from other countries. The bovine strain belonging to the A.Br.008/011 lineage differed from a former Japanese vaccine strain by only 12 SNPs. Together with the phylogenic results and epidemiological circumstances, the diversity of strains reveals that the B. anthracis available in Japan probably resulted from multiple relatively recent import events, rather than reflecting the persistence of a more ancient ecologically established group.

Draft Genome Sequence of Mycobacterium virginiense Strain GF75, Isolated from the Mud of a Swine Farm in Japan.

ABSTRACTMycobacterium virginiense, a newly described species of the Mycobacterium terrae complex, is a cause of tenosynovitis and osteomyelitis in the United States. Here, we report the 4,849,424-bp draft genome sequence of M. virginiense strain GF75, isolated from a mud sample taken from a Japanese swine farm.

Characterization of porcine sapelovirus isolated from Japanese swine with PLC/PRF/5 cells.

Porcine sapelovirus (PSV) is a causative agent of neurological disorders, fertility disorders and dermal lesions of swine. In this study, we isolated two PSV strains, Jpsv477 and Jpsv1315, from swine faecal specimens using a PLC/PRF/5 cell culture system. The PSV infection of PLC/PRF/5 cells induced a cytopathic effect (CPE). Two types of virus particles with identical diameter (~35nm) but different densities (1.300 and 1.285g/cm3 ) were observed in the cell culture supernatants. Analysis of the entire genome sequence of Jpsv477 and Jpsv1315 revealed that both strains possess 7,558 nucleotides and the poly (A) tail and have a typical PSV genome organization consisting of a 5' terminal untranslated region (5'UTR), a large open reading frame (ORF), and a 3' terminal untranslated region (3'UTR). The ORF encodes a single polyprotein that is subsequently processed into a leader protein (L), four structural proteins (VP1, VP2, VP3 and VP4) and seven functional proteins (2A, 2B, 2C, 3A, 3B, 3C and 3D). The structural proteins VP1, VP2, VP3 and VP4 have molecular masses of ~35, ~26, ~25 and ~6kDa. The N-terminal amino acid sequence analysis of VP1, VP2, VP3 and VP4 confirmed that the cleavage sites between VP4 and VP2, VP2 and VP3, and VP3 and VP1 are K/A, Q/G and Q/G, respectively. We further confirmed that HepG2/C3A, Vero E6 and primary green monkey kidney cells (PGMKC) were also susceptible to PSV infection. The stability assay demonstrated that PSV was inactivated by heating at 60°C for 10min or 65°C for 5min. The virus also lost infectivity by incubation with 62.5ppm of NaClO for 30min.

Genetic relatedness between Japanese and European isolates of Clostridium difficile originating from piglets and their risk associated with human health.

Clostridium difficile colonization in pig intestine has been a public health concern. We analyzed C. difficile prevalence among piglets in Japan to clarify their origin and extent of the associated risk by using molecular and microbiological methods for both swine and human clinical isolates and foreign isolates. C. difficile was isolated from 120 neonatal piglet fecal samples. Toxin gene profile, antimicrobial susceptibilities, PCR ribotype, and multiple-locus variable-number tandem-repeat analysis (MLVA) type of swine isolates were determined and compared with those of human clinical and foreign isolates. One-hundred C. difficile strains were isolated from 69 (57.5%) samples, and 61 isolates (61%) were toxin gene-positive. Some isolates were resistant to antimicrobials, contributing to antibiotic-associated diarrhea by C. difficile. These results suggest that C. difficile, prevalent among Japanese pigs, is a potential risk for antibiotic-associated diarrhea. Furthermore, PCR ribotype 078 (12 isolates), which has been linked to multiple outbreaks worldwide, was the third-most frequently isolated of the 14 PCR ribotypes identified. Moreover, MLVA revealed that all 12 PCR ribotype 078 isolates were genetically related to European PCR ribotype 078 strains found in both humans and pigs. To date, in Japan, many breeding pigs have been imported from European countries. The genetic relatedness of C. difficile isolates of Japanese swine origin to those of European origin suggests that they were introduced into Japan via imported pigs.

Quantitative associations between outdoor climate data and weaning-to-first-mating interval or adjusted 21-day litter weights during summer in Japanese swine breeding herds

The objective of the present study was to quantify the associations between climate data and either weaning-to-first-mating interval (WMI) or adjusted 21-day litter weights of sows during summer for different herd productivity groups. This study was conducted using 87,428 parity records of 61,558 sows farrowed between June and September in 2007, 2008 and 2009, in 103 Japanese herds mostly located in humid subtropical areas. The 103 herds were classified into high-performing herds and ordinary herds by the basis of the upper 25th percentile of pigs weaned per mated female per year, averaged over the three years. The climate data were obtained from 21 weather stations of the Japan Meteorological Agency. Average values of the daily maximum temperatures (HT), average daily relative humidity (RH) and temperature-humidity index (THI) for 21 days after the farrowing date of a sow were coordinated with sow performance data from a recording system. Two-level mixed-effects models were applied to the data by using a herd at level 2 and an individual record at level 1. Mean values (ranges) of HT, RH and THI were 27.8°C (17.3–36.0°C), 74.6% (57.3–90.9%) and 22.2°C (13.0–27.4°C), respectively. Higher HT, RH and THI were associated with higher WMI and lighter adjusted 21-day litter weights (P<0.05). High-performing herds had lower WMI and heavier adjusted 21-day litter weights than ordinary herds at any HT, RH and THI (P<0.05). The WMI of sows in high-performing herds did not increase as much as those in ordinary herds when HT or THI increased. For example, as HT increased from 25 to 35°C, WMI of sows in high-performing herds increased by 0.3 days, whereas those in ordinary herds increased by 0.8 days. Also, when HT, RH or THI increased, parity 1 sows showed greater increase in WMI than parity 2 or higher sows (P<0.05). For instance, as THI increased from 15 to 25°C, WMI in parity 1 sows increased by 0.9 days, whereas those in parity 2 or higher sows increased by only 0.3 days. In conclusion, high-performing herds alleviate the negative effects of humid subtropical summer climates on WMI or adjusted 21-day litter weight more than ordinary herds. The parity 1 sows were more sensitive to such summer changes in climate than parity 2 or higher sows. Therefore, it is recommended in particular for parity 1 sows that producers practice cooling management during summer.

疫学調査におけるデータの取り方

Appropriate research planning is important to utilize various types of data from the field. This includes selection of research methods, sampling schedules, diagnostic techniques, data managements, utilization of computer software and feedback of the results. A new benchmarking system (PigINFO) has been developed for Japanese swine farms with collaboration of National Institute of Animal Health (NIAH) and Japanese Association of Swine Veterinarians (JASV). In this system, production data obtained from farms are submitted to NIAH for analysis, and the results are returned to farmers by the veterinarians in JASV. Accumulated data through this system has been utilized for epidemiological studies such as the observation of the annual trends of farm productivities and their associations with the existence of some diseases. Data from the field will contribute to a variety of epidemiological research, resulting in benefit for animal owners and veterinarians.

Correlation between villous height and the disaccharidase activity in the small intestine of piglets from nursing to growing

Early weaning induces villous atrophy in the small intestine. Reduction in villous height in the small intestine after weaning is associated with reductions in brush-border enzyme activity. Body weight gain after weaning is, therefore, correlated with villous height. This evidence suggested that the maintenance of small intestinal structure and function after weaning is important for the growth of young pigs. On the other hand, the relationship between villous height and the activity of the digestive enzymes in the small intestine has not been studied with piglets from the suckling to the growing period. Five suckling piglets, four piglets in the proximal stage of weaning, four pigs in the distal stage of weaning and four growing pigs were used. The activities of lactase (LA), sucrase (SA) and maltase (MA) were determined. LA showed a positive correlation with villous height in weaning. SA and MA were positively correlated with villous height from suckling to growing. In a previous study, non-infectious dyspeptic diarrhea was frequently observed in growing piglets on Japanese swine farms. The maintenance of villous height to retain disaccharidase activity may prevent dyspepsic diarrhea in this stage.

Presence of Staphylococcus aureus ST398 and ST9 in Swine in Japan

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is mainly associated with swine and is capable of causing zoonotic infections. The methicillin-resistant S. aureus (MRSA) multilocus sequence type (ST) 398 of swine origin is predominant in Europe and North America, whereas ST9 is predominant in Asia. To evaluate the possible emergence of MRSA in swine, we examined the ST and spa type of 15 methicillin-susceptible S. aureus (MSSA) isolates obtained from swine in 8 different prefectures from north to south Japan between 2003 and 2009. Sequence analyses revealed that 6 porcine MSSA isolates belonged to ST398; 6 to ST9; and 1 each to ST5, ST97, and ST705. Of the 6 MSSA ST398 strains, 4 were classified as spa type t034. This study illustrated that there is a reservoir in Japanese swine of livestock-associated MSSA types.

Pork Production in China, Japan and South Korea

ABSTRACT : Global pork markets are becoming more competitive, riding the wind of the bilateral free trade agreement. China is the world’s largest pork producer with nearly 50% of the world’s total production. China’s fast growing economy has provided its people with higher purchasing power, resulting in a rapid expansion of the Chinese swine industry over the past decades. Worldwide, China consumes the greatest amount of pork and it is believed that this trend will continue. Japan is the world’s largest pork importing country,even though it also produces a lot of pork. The Japanese swine industry encounters weighty obstacles in production costs and environmental limitations which result in reduced domestic supply and creates the situation in which Japan has to import a significant amount of pork for their consumption. South Korea is also a large buyer of pork, with a status greatly influenced by the struggle that the country has faced with Foot and Mouth Disease (FMD) which occurred in 2000, 2002 and 2010. High production costs, low production efficiency, and forced culling following the FMD outbreak resulted in the loss of many hog farming households in the country, reducing supply of domestic pork in the face of continued demand. Overall, pork production in these economically important countries can greatly impact the industry globally. The goal of this review paper is to describe pork production in China, Japan, and South Korea and discuss these countries’ role in global pork export markets. (

Isolation of meticillin-resistant Staphylococcus aureus (MRSA) from swine in Japan

Meticillin-resistant Staphylococcus aureus (MRSA) sequence type (ST) 398 is widely prevalent in swine in Europe and North America. To determine the prevalence of MRSA, and specifically ST398, in Japanese swine, a total of 115 nasal swabs and 115 faecal samples from swine reared at 23 farms located in eastern Japan were investigated. MRSA was isolated from a nasal sample (0.9%) but not from any faecal samples. The strain of MRSA was classified as ST221 by multilocus sequence typing and as t002 by spa typing. The MRSA isolate exhibited resistance to ampicillin, meticillin and dihydrostreptomycin. Interestingly, it remained susceptible to cefazolin, ceftiofur, imipenem, gentamicin, kanamycin, chloramphenicol, oxytetracycline, erythromycin, azithromycin, tylosin, vancomycin, enrofloxacin and trimethoprim. The prevalence of MRSA amongst swine was low and MRSA ST398 was not recovered in the present study.

The occurrence of decreased numbers of pigs born alive in parity 2 sows does not negatively affect herd productivity in Japan

The objectives of this study were to assess the occurrence of decreased numbers of pigs born alive (PBA) in parity 2 (D-PBA) and to evaluate the importance of D-PBA sows and herds by analyzing against using the summed numbers of PBA in parity 1 and 2 (SPBA) and nonproductive sow days (NPD). The study assessed annual data from 2001 to 2005 from 106 herds, and sow data including 137,360 farrowing records of 68,680 sows farrowed in parity 1 and 2. D-PBA was defined as the same or fewer numbers of PBA in parity 2 than that in parity 1 at either the sow or herd level. Sows or herds were categorized into two groups: D-PBA or increased PBA in parity 2 (I-PBA). NPD was defined as the number of days that sows were neither gestating nor lactating in parity 1. Mixed-effects models were used to compare the reproductive performance between the two groups. Of the 68,680 sows, 49.5% had an occurrence of D-PBA. D-PBA sows had 0.3 pigs fewer SPBA than I-PBA sows, but those sows had 1.9 days shorter NPD in parity 1 than I-PBA sows ( P < 0.05). Over the five years studied the average annual proportion of D-PBA herds was 16%. No differences were found between the D-PBA and I-PBA herds in the number of pigs weaned per mated female per year (PWMFY), SPBA or NPD in any year. Additionally, the PWMFY was not correlated in any years with either the proportions of D-PBA sows or the difference in PBA between parity 1 and 2. In conclusion, the occurrence of D-PBA does not appear to be a serious problem in Japanese swine herds studied.

Prevalence of swine Torque teno virus genogroups 1 and 2 in Japanese swine with suspected post-weaning multisystemic wasting syndrome and porcine respiratory disease complex

Torque teno virus (TTV) was first isolated from a human hepatitis patient in 1997. TTV was also identified in several animals, including pigs, cattle, sheep, cats and dogs. In this study, we analysed the prevalence of swine TTV genogroups 1 (TTV1) and 2 (TTV2) in Japanese swine populations with suspected post-weaning multisystemic wasting syndrome and porcine respiratory disease by using a nested polymerase chain reaction method. Of 153 serum samples from 16 different herds in Japan, TTV1 was detected in 46 samples (30%), TTV2 in 47 samples (31%) and both in 15 samples (10%). There was no significant difference in the detection rate among geographical regions. The overall prevalence rate of TTV genogroups was significantly lower in ≤30-day-old pigs (11%) compared to that in older age groups (54–82%). These results suggest that swine TTV may be widespread in post-weaning pigs and could play aetiological roles in pig diseases in Japan. This is the first report on the prevalence of swine TTV in Japan.

Molecular characterization and phylogenetic analysis of the complete genome of a hepatitis E virus from European swine

Hepatitis E virus (HEV) has been detected in humans and in a broad range of animals, including pigs. For the first time the full-length genomic sequence of a HEV of European porcine origin, termed swX07-E1, was determined. Comparative analysis of 76 complete or nearly complete nucleotide sequences showed that swX07-E1 shares the highest nucleotide identity with Japanese swine HEV swJ8-5 and swJ12-4. The whole-genome phylogenetic analysis showed that swX07-E1 from Europe belongs to genotype-3 HEV, clusters with variants from Japan, Mongolia and Kyrgyzstan in subgroup 3c, but it is divergent from the prototype US HEV. Our analysis indicates that swX07-E1 represents a new subgroup of genotype-3 and that analysis of full-length sequences is necessary to discover new subgroups of HEV. According to our knowledge, swX07-E1 is the first full-length genome sequence of HEV from European swine. Knowledge about the full length HEV sequence from European swine is very important for understanding the HEV evolutionary events and the molecular mechanism of infection in human and in animals.

Existence of reassortant A (H1N2) swine influenza viruses in Saitama Prefecture, Japan

During two winter seasons between 1999 and 2001, seven strains of influenza virus were isolated from healthy pigs in Saitama Prefecture, Japan. All isolates were identified as A (H1N2) reassortant viruses. Genetic and phylogenetic analyses indicated that they had classical swine-like hemagglutinin (HA) and internal genes, and relatively early human-like neuraminidase (NA) gene. The HA and NA genes belonged to unique clusters of Japanese swine strains.

Achieving a Nitrogen Balance for Japanese Domestic Livestock Waste: Testing the Scenario of Planting Feed Grain in Land Left Fallow

In this study, we assess the recent changes in the amount of excretion by the livestock industry, and discuss the effects of increasing the ratio of cultivated land on the reduction of surplus nitrogen from a cost-performance perspective. Nitrogen has contributed to acidification of ecosystems and nitrate concentrations in groundwater, especially in Europe. Therefore, we assessed the level of nitrogen waste from the domestic Japanese livestock industry, including cattle, swine and poultry during the period 1987-2001. This assessment assumed that 40% of the nitrogen from the domestic livestock industry was emitted as gas into the air and that 60% of the nitrogen was contained in manure used on domestic cultivated land. Nitrogen excreted from livestock, excluding gas emission, decreased by 11% from 0.504 million tons to 0.447 million tons during 1993-2001. Thus, the peak period of nitrogen excretion from livestock is already past in Japan. However, the area of cultivated land under management also decreased during 1990-2000. In addition, the area of paddy and upland fields left unplanted for a year increased during 1990-2000. Therefore, if all manure from the domestic livestock industry had been utilized on the fields as organic fertilizer, but not on arable land left uncultivated for the past year, the nitrogen per net area of cultivated land would have increased by 5%, from 125 to 131 N kg/ha, during 1990-2000. To reduce the nitrogen ratio on cultivated land through the planting of feed grain to utilize the nitrogen, a comparison of the cost performance of feed grains indicated that barley would be more suitable than wheat, rice or soybean. Had barley been planted in 100% of the land left fallow for the past year in 2000, 4% (20,000 tons) of the nitrogen from livestock waste would have been used in the harvest, and the nitrogen per land unit would have not increased but decreased from 125 to 121 N kg/ha during the same decade. Furthermore, when converted into Total Digestible Nutrients, 7% of imported feed corn could have been replaced with the harvested barley in 2000. Planting barley on this fallow land had three benefits; reducing the risk of manure overload on the land, slowing down the decrease in cultivated land, and raising the feed self-sufficiency ratio. Thus, it would be beneficial to plant feed grain such as barley in land left fallow for the past year through utilization of manure.

Characterization of Japanese swine and human hepatitis E virus isolates of genotype IV with 99 % identity over the entire genome.

The full-length genomic sequences were determined of Japanese swine and human hepatitis E virus (HEV) isolates (swJ13-1 and HE-JA1, respectively) with 100 % identity in the partial sequence of open reading frame (ORF) 2 (ORF2, 412 nt). swJ13-1 was isolated from a 4-month-old farm pig born in Hokkaido, Japan, in 2002 and HE-JA1 was recovered from a 55-year-old patient who lived in Hokkaido and who had contracted sporadic acute hepatitis E in 1997. Both isolates consisted of 7240 nt, excluding the poly(A) tail, and contained three ORFs (ORFs 1-3) that encoded proteins of 1707, 674 and 114 aa. The overall nucleotide sequence identity between them was 99.0 % and the deduced amino acid sequence identities of ORFs 1-3 were 99.8, 100 and 100 %, respectively. The high degree of genomic similarity observed between swine and human HEV isolates in a restricted area of Japan further supports the finding that sporadic hepatitis E in Japan is a zoonosis.

Reproductive productivity measurements in Japanese swine breeding herds.

To set productivity standards and targets, and investigate inter-relationships between key measurements in swine breeding herds, farm productivity measurements were analyzed on 87 Japanese commercial farms in 14 prefectures. The 87 herds were ranked on the basis of number of pigs weaned per mated female per year (PWMFY), and 23 herds in the upper 25th percentile of this ranking were designated as high-performing farms. Productivity measurements on the high-performing farms were compared with values for the remaining farms. The high-performing farms had shorter farrowing intervals, greater litters per mated female per year (LMFY), greater pigs weaned per sow (PWS), and greater mean parity of culled sows than the remaining farms (P<0.01). No difference in lactation duration was found between the two groups (P>0.10). For both farm groups, correlations of key reproductive measurements were determined. Lactation duration was not correlated with LMFY, PWS and PWMFY on the high-performing farms, while short lactation duration was correlated with greater LMFY and PWMFY on the remaining farms (P<0.01). In contrast to lactation duration, farrowing interval was correlated with PWS on the high-performing farms, but not on the remaining farms. Mean parity of culled sows were correlated to PWS and pigs born alive per sow on the high performing farms, but not with any measurements on the remaining farms. These results suggest that high-performing farms have used different herd management from the remaining farms.

Antibody responses of swine to type A influenza viruses during the past ten years in Japan.

A total of 6346 swine sera collected at an abattoir in the city of Obihiro, Hokkaido during the years 1978-87 were tested for the presence of antibodies to swine and human influenza viruses. A high incidence of antibody to A/New Jersey/8/76 (swine type H1N1) virus was observed throughout the 10 years except for the occasional month and a single long period of 15 months. Antibodies to human H3N2 virus in swine appeared to be related to the epidemics of human influenza which occurred in the study area during the years 1980-3, but unrelated to the epidemics during the years 1984-7. A large number of swine were found to be antibody positive to a human H1N1 virus during the period April to June 1964, and a smaller number, during the period November 1986 to June 1987. Both were in relation to human influenza epidemics. However, there were long periods where human H1N1 antibodies in swine could not be found.