近年ウガンダの酪農業は集約化が進み，牛群管理と乳牛の栄養状態への影響が懸念されるが，ウガンダ南西部の牛群管理の現況は報告されていない。本横断研究は，牛群の飼養管理状況を記述し，飼料給与と乳量・血中ケトン体濃度の関係を調査することにより，この地域における飼養方法の現状を把握し今後の発展のための方向性を見いだすことを目的に実施した。

2016年10月から2017年3月に30農場の506成乳牛を対象に聞き取り調査を実施した。飼料給与が乳量と血中β-hydroxybutyrat濃度（BHB）へ及ぼす効果を推定するため原因図式により交絡因子を選択し，混合効果モデルを用いた多変数解析を実施した。

平均牛群規模は35.5頭，平均乳量は9.8L，外来種は74.5%を占めた。濃厚飼料は40%，粗飼料は70%の農場で給与され，放牧は93.3%の農場で実施されていた。分娩後21日以内の牛のケトーシス（潜在性ケトーシス（SCK）を含む）の有病率は10.8%（4/37, 95%信頼区間：3.0-25.4%）であった。濃厚飼料を給与した牛の乳量（9.20L）は非給与牛（5.95L，p＝0.041）より高かった。全対象牛のうち輪換放牧を実施していた牛の乳量（5.78L）は輪換放牧を実施していなかった牛（3.46L，p＝0.017）より高かった。飼料給与はBHBに有意な影響を与えなかった（p＝0.092）。

ウガンダ南西部では外来種が多く導入されており，適切に栄養管理をすることで高い産乳性を期待できることが示された。

サルモネラに感染した搾乳牛は，時としてサルモネラを長期間保菌し，大きな経済損失が発生する。今回，サルモネラの長期間保菌要因の一つと考えられる第一胃発酵状態について，牛のサルモネラ保菌陰転率（陰転率）との関連を隠れマルコフモデルを用いて評価した。調査農場はサルモネラ症が発生した一酪農場で，搾乳牛21頭の糞便培養検査が対策終了までの約1年間に約2週間間隔で23回実施された。第一胃発酵状態は乳脂肪率/乳タンパク質率比（FPR）により推測した。FPR≧1.1かつ≦1.5を正常（OC），発酵不足であるFPR>1.5を栄養不足（NEB），発酵過剰であるFPR<1.1をルーメンアシドーシス（RA）とした。OCの牛に対するNEB及びRAの牛の陰転率のオッズ比は，それぞれ0.0141（95%信用区間：1.08×10^－26，2.75）及び0.0429（95%信用区間：2.00×10^－14，0.628）と推定された。今回の調査から，第一胃発酵状態が異常である牛はサルモネラが排除されにくい可能性があると考えられた。

On 5th January 2020, World Health Organization notified all member states about the new outbreak of pneumonia of unknown cause in Wuhan City, Hubei Province of China. It was a beginning of pandemic of the novel transmissible disease, which was later named as COVID-19. The causative agent was soon searched using whole genome analysis and a new coronavirus that is very similar to the virus causing SARS was identified. The virus was named SARS-CoV-2. COVID-19 rapidly spread inside China and the Government of China decided to shut all public transportation at the end of January. In Japan, a man who travelled back from Wuhan city in early January was the first case. To rescue Japanese nationals trapped in Wuhan, the Japanese Government chartered five flights. All passengers were put under quarantine after arrival and were subjected to PCR testings. On 1^st February, a passenger on a cruise ship ‘Diamond Princess’ that had departed from Yokohama was confirmed to be infected with SARS-CoV-2 at Hong Kong. Therefore, all passengers and crews on the ship were put under quarantine offshore Yokohama, the final destination of the cruise. PCR testings were performed on symptomatic persons and persons that had close contact with cases. The number of cases increased day by day from the start of the quarantine. Epidemiological research was conducted worldwide from an early stage and demonstrate good indices to understand epidemiology of COVID-19. Case reports from China showed presence of many asymptomatic cases especially in younger generations. Mathematical modelling studies estimated the length of incubation period of COVID-19 and its serial interval and the possibility of transmission during asymptomatic period was also highlighted to give warning. Effectiveness of the quarantine measures on the Diamond Princess was evaluated in another study and drastic reduction of the predicted number of future cases was proven. At the end of February, a specialist advisory group was organized under the Ministry of Health, Labor and Welfare. Advised by this group, Japan started to tackle COVID-19 by applying a unique strategy in the world.

Regression modelling is a popular approach for analysing epidemiological data. While its analytical techniques are widely covered by standard textbooks, modelling approaches vary between disciplines, potentially confusing many users. Identifying the motivation behind epidemiological analyses, particularly understanding of causal inference, would naturally guide users. Nevertheless, this subject has not been taught systematically in many of the veterinary epidemiology curriculums. This series of articles aim to showcase the minimum standard for regression modelling, highlighting basic concepts such as confounding. In this first article, a regression modelling approach to making causal inference is explained.