The starting point of epidemiology is an infectious disease though epidemiological study is applied to various fields. Moreover, there are several peculiar features to the epidemiology of the infectious disease; (1) “case (infected animal)” becomes “risk factor” to following infection, (2) infected animal usually acquires immunity against pathogen, (3) some infectious diseases have kept persistent or latent infection with unclear clinical symptoms which is not recognized easily, and so on. Epidemiological approach of infectious diseases basically is executed in order of descriptive study, analytic study and countermeasures against infectious diseases. Therefore, the final goal is “Suppression of the infectious disease”. For control of infectious diseases, it is necessary to know three factors indispensable to approve infectious disease ; pathogen, route of transmission, and susceptible host. Moreover, it is also important in the epidemiology of infectious diseases to evaluate effect of countermeasures after carrying out them.

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Concept of risk analysis introduced into food safety management in Japan to recover consumer confidence to the Japanese food safety policy after finding of first Bovine Spongiform Encephalopathy (BSE) cattle in September, 2001. Risk analysis consists of three components, risk management, risk assessment, and risk communication. Food Safety Commission (FSC) was established in Cabinet Office as a risk assessment organization in July, 2003. Ministry of Health and Welfare and Ministry of Agriculture, Forest and Fisheries are risk management organizations, they take management action after risk assessment by FSC.
Counter measures against BSE, including feed ban, importation ban for Meat-and-Bone-Meal, removal of specified risk material (SRM), BSE testing for cattle of all age, and BSE testing for fallen stock in a farm were taken. 36 BSE cattle were found with BSE testing without any symptoms of BSE in a healthy slaughter and fallen stock.
Age of BSE testing was amended from all age to over 21 months since July, 2005, according to the results of BSE risk assessment by FSC. FSC compared with qualitative risk of BSE infectivity in live cattle and contamination of beef with BSE prion, when changing of age of BSE testing for cattle with all age to over 21 months age. FSC concluded that the risk of changing age of BSE testing is negligible to very low with risk assessment results
However, BSE testing for all age of cattle by the local government was continued until April, 2013, depending on the risk communication with stakeholders.
Number of BSE cattle decreased worldwide, cattle with positive test result of BSE testing was not found in Japan since February, 2002. Japan was decided as "negligible BSE risk" country by Office of Animal Health in May, 2013. BSE risk decreased in Japan. Therefore, BSE risk assessment was conducted about the risk difference, when changing the age of BSE testing from over 21 months to over 30 months or more and age of removal of SRM from all age to over 30 months.
Points of risk assessment are follows,
① Passing years after birth date of last BSE case
② Passing years after total feed ban and effectiveness of BSE counter measure
③ Experimental results of oral transmission of BSE with 1g of brain of BSE
④ Relationship between incubation period and amount of intake of BSE prion
According to the data of Europe Union, 97% BSE cattle was detected until 11 years of age. Therefore, if BSE prion were not detected for 11 years in cattle population, there is very low possibility to find new BSE case. New BSE case was not found since February, 2002 as described above. When BSE counter measures will be continued, the possibility of detection of new BSE cattle is considered negligible.
Furthermore, risk assessment for whether the possibility of detection of new BSE case in the birth cohort after indicated year become negligible or not was conducted. Then, whether continuation of BSE test over indicated month of age is necessary or not is discussed.
Results are follows
1. Last BSE case was detected in the cattle younger than 48 months of age. According to the EU data, 98% BSE test positive cattle was estimated over 48 months of age.
2. BSE prion was detected in the brain tissue after oral inoculation of 1g of BSE cattle-brain after 44 months (48 months of age)
3. Incubation period is prolonged along with injestion of the lower amount of BSE prion protein
Depending upon the above results, risk of BSE to human is considered negligible after amendment of BSE test-age of months from 30 to over 48 months of age of healthy cattle in the slaughter house.
On the other hand, target age of months of cattle for SRM is amended from all age to over 30 months of age similar to OIE code, because of the risk assessment results with negligible risk of beef to human.

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A large-scale foot-and-mouth disease (FMD) epidemic occurred in Japan in 2010. During the epidemic, the emergency vaccination strategy was conducted for the first time in Japan. Ultimately, this epidemic was contained within 3 months, and then led a total of 292 detected farms and nearly 290,000 culled animals including vaccinated animals. Such a large-scale epidemic of FMD has never experienced in Japan, and it caused severe damage to the local livestock industry and related industries. In this article, some epidemiological analyses of the FMD epidemic are introduced.
First, descriptive and spatial analyses were conducted to understand the character of the epidemic. The epidemic was primarily localized within 20km of the north-south area of Miyazaki Prefecture. The epidemic area features a densely populated livestock area even in Miyazaki, which has been known as one of the major livestock farming regeion in Japan. A spatial clustering of the disease was detected by the spatial analysis and this cluster was located in an area more densely populated with both cattle and pig. This implies that high density of livestock animals was a crucial aspetc of the epidemic and pig farms played an important role to induce the dissemination of the disase in the area.
Next, a case-control study was conducted to investigate the risk factors associated with FMD transmission under the movement restriction. This study resulted that in the highly affected area the disease was likely to spread regardless of the movements of people and vehicles, and physical barriers around barns such as walls or clumps of trees were found to be a protective factor. Meanwhile, in the less affected area movements of people and vehicles was strongly associated with the disease spread.
Lastly, an FMD transmission model was developed using the epidemic data to evaluate the effects of several control measures.The transmission model demonstrated that prompt culling on infected farms or early detection of an index case could contribute effective and efficient prevention of the disease spread in the epidemic area. As an optional strategy, preemptive culling demonstrated good effectiveness in reduction of the number of infected farms. However, applying this strategy in the densely populated areas may have practical difficulties because it required a large amount of resources. The vaccination strategy with the wide range in the early phase of the epidemic also showed the potential to contain the epidemic on a small scale, but vaccination strategy posed some difficulties in management of vaccinated animals whether they are culled or not.

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From March 2012 to October 2013, 145 cases including 62 deaths of Middle East respiratory syndrome (MERS) have been identified in 9 countries (Saudi Arabia, UAE, Qatar, Jordan, France, Germany, Italy, Tunisia, and UK). Recent studies say, while MERS appears to be more deadly in those it infects, it also seems to be less contagious than severe acute respiratory syndrome (SARS) in 2003. All primary cases were connected to the Arabian Peninsula, and nearly half of the cases died due to severe lung inflammation. Nosocomial transmission was implied in 26 percent of the cases. Human-to-human-transmission was considered the likely source of infection in hospital. From these cases, the median incubation period was estimated as 5.2 days (95 percent confidence interval 2 to 15 days). At the same time, some asymptomatic or mildly symptomatic cases have been reported. All MERS-positive cases were diagnosed by using real-time RT-PCR targeting upE and Orf1a genes of MERS-CoV. Specimens were taken from the upper or the lower respiratory tract and blood. Even though over a year has passed since the emergence of the 1st case, many questions on the origin and transmission patterns of the disease remain. The pathogen of MERS belongs to the lineage C of the beta coronaviruses (CoV), which are genetically similar to various coronaviruses detected in bats in Africa and Europe. And two studies suggest dromedary camels in Oman, the Canary Islands and Egypt may have been infected with the virus or a MERS-CoV-like virus in the past. However, human cases have not been detected in these areas. With the Hajj, the Muslim pilgrimage to Mecca in Saudi Arabia, taking place in October 2013 and attracting 3 million visitors, international public health efforts to mitigate and possibly contain this outbreak need to be reinforced. On alert for a possible pandemic, we prepared the PCR system, and shared it to 74 locations of prefectural public health institutes and quarantines in Japan.

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The objective of the present study was to advance the development of standard operating procedures for postweaning sows by determining associations between the operating procedures and sow reproductive performance. Questionnaires were sent to 115 herds that use the same recording system. The questionnaires included questions about procedures for weaned sows in 2008, such as the type of boar contact for estrus detection, time of insemination and the feeding procedure after insemination. Data from 95 completed questionnaires (82.6%) were coordinated with the reproductive data for relevant individual females (71,743 service records) extracted from the recording system. Two-level mixed-effects models were applied using a herd at level 2 and an individual record at level 1 to determine associations between the surveyed procedures and farrowing rate or pigs born alive. Sows were separately analyzed by four weaning-to-first-mating interval (WMI) groups : WMI 4, 5, 6, and 7 days or later. Means (±SEM) of farrowing rate and pigs born alive were 86.9±0.13% and 11.0±0.01 pigs, respectively. The farrowing rate and pigs born alive were associated with the use of direct boar contact, the timing of first insemination and decreasing diet quantity after insemination (P‹0.05). More specifically, decreasing diet quantity after insemination was associated with improving farrowing rate of parity 1 sows. Parity 1 sows with WMI 4, 5 and 7 days or later had 0.1-5.7% higher farrowing rates in the herds that decreased diet quantity after insemination compared to those in the herds that did not decrease diet quantity (P‹0.05). However, there were no such differences in sows at parity 2-5 and 6 or higher. Our survey indicates that postweaning management procedures should take account of WMI and parity.

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Staphylococcus aureus is the most important gram-positive bacteria causing bovine mastitis. In Engaru-cho, Hokkaido, Japan, the increase of S. aureus mastitis was subjectively observed in 2005 after the introduction of anonymous post-milking dipping Iodine-based product A. The present study was conducted to investigate the association between this product and the incidence of S. aureus mastitis.
Nine farms which experienced S. aureus mastitis were selected and the data stored in Okhotsk Agriculture Mutual Association on the diagnoses with S. aureus mastitis and husbandry practice between April 2005 and March 2007 were used for the analysis. Generalized Estimating Equations (GEE) were performed to examine the association between teat level incidence rate of S. aureus mastitis and farming style, types of pre milking teat disinfectants and post milking teat dip products. A stochastic decision tree analysis was performed for economic analysis.
The use of post-milking teat dip product A was a single risk factor ; the adjusted annual incidence rate was 3.0% (95%CI : 1.5%—5.8%) while that of product B 1.1% (95%CI : 0.6%—2.2%, p=0.042). Although the price of the product B was 1.5 times more expensive than A, the annual cost controlling S. aureus mastitis per teat using the product B was cheaper (JPY 837, 95%CI : 681—1,134) than that of product A (JPY 1,212, 95%CI : 796—2,020).
The degradation of teat skin caused by the lower pH and glycerol concentration of the product A might be the cause of the elevated incidence. The use of Epidemiological and economic analyses were proved to be useful in evidence-based veterinary medicine.

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Rabies situation in different parts of the world is reviewed with emphasis on wildlife rabies. Measures required for the prevention and control of wildlife rabies are listed, and it is stressed that the Ministry of Environment should play a major role in planning and implementing programs related to surveillance and control of wildlife rabies. It is also suggested that veterinary schools and the wildlife research institutes in Japan could form a group to carry out various research and investigations on the subjects related to the surveillance and control of wildlife rabies both in Japan and in the neighboring countries.

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After the chytrid fungus was first discovered in Japan, studies have revealed the following facts,
1)Chytrid fungus is present naturely in Japan.
2)Japanese native amphibians are resistant to chytrid fungus.
3)Wild chytrid fungus in Japan has many haplotypes. In other words, this organism has surprising diversity in Japan. The chytrid fungus that originates from the Giant salamander shows a unique genetic cluster of haplotypes.
On the basis of these facts, we propose a new hypothesis, i.e., “Chytrid fungus has coevolved with native amphibians as a natural host in East Asia, including Japan.”. In other words, in the long process of the evolution of chytrid fungus and amphibians in East Asia, an equilibrium has formed between the hosts (amphibians) and the pathogen (chytrid fungus) which has continued up to the present. This hypothesis may explain the present state of chytrid fungus in Japan.
To prove this hypothesis, it is necessary to survey and analyze the genetic and ecological characteristics of chytrid fungus around the world, and research in East Asia is a priority.

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