タンザニア国牛ブルセラ病常在地域における持続的かつ支払可能な疾病制御法の検討

Brucellosis is a zoonotic disease spreading across the world. Although the cases and burden of the disease are tremendous, the disease control by the government is not expected due to the lack of recourses in many developing countries. This study was carried out to explore the sustainable and affordable control options of bovine brucellosis in Morogoro region, Tanzania. First study was conducted as a cross-sectional study to compare prevalence and risk factors of bovine brucellosis, and risky behaviours for the human infection between urban and agropastoral areas. Cattle blood sampling and interviews using a structured questionnaire were conducted with farmers. Rose-Bengal test was conducted for the cattle sera, and positive samples were confirmed with competitive ELISA. Farm-level sero-prevalences were 0.9% (1/106, 95% CI: 0.0–5.9%) and 52.9% (9/17, 95% CI: 28.5–76.1%) in urban and agro-pastoral areas, respectively. The animal-level adjusted prevalences were 0.2% (1/667, 95% CI: 0.0–1.1%) and 7.0% (28/673, 95% CI: 5.7–8.4%) in those areas. The final farm-level model including both areas found two risk factors: history of abortion in the herd (P < 0.01) and cattle grazing (P = 0.07). The animal-level risk factors in agro-pastoral areas were age (P = 0.04) and history of abortion (P = 0.03). No agro-pastoral farmer knew about Brucella vaccine. Agro-pastoralists generally had poorer knowledge on brucellosis, and practiced significantly more risky behaviours for human brucellosis such as drinking raw milk (17.6%, P < 0.01) and blood (35.3%, P < 0.01), and helping cattle birth (100%, P = 0.04) than urban farmers (0%, 0% and 79.2%, respectively). Intervention programmes through education including both human and animal health particularly targeting agro-pastoralists would be needed. Thus second study was performed focusing on agro-pastoral areas, investigating the farm level prevalence and risk factors for bovine brucellosis, and perception and behaviours related with brucellosis control among agro-pastoralists. A cross-sectional study involving herd milk diagnosis by Indirect ELISA and questionnaire survey was conducted in 124 farms. The questions included potential risk factors, knowledge of brucellosis, willingness-to-pay for cattle vaccination, and Item Count Technique (ICT) for selling behaviour of cows experienced abortion. The knowledge on brucellosis among study farmers was poor (name of the disease: 13.7%, symptoms: 3.2%, transmission from cattle to human: 2.4%, and Brucella vaccine: 2.4%). The farm-level bovine brucellosis prevalence was 44.4% (55/124, 95% CI: 35.5–53.5). There was no risk factor for bovine brucellosis but a preventive factor, using veterinary service (OR = 0.39, 95%CI: 0.18—0.84, P = 0.02). For the scenarios of vaccinating all cattle and only calves, 59.7% and 89.5% of farmers were willing to pay for vaccination. Being Maasai tribe was a hesitating factor for vaccinating all cattle (OR = 0.39, 95%CI: 0.19—0.83, P = 0.01) and using a veterinary service an encouraging factor for vaccinating calves (OR = 4.0, 95%CI: 1.2—13.0, P = 0.02). The ICT found that 45.1% of the farmers sold out cows that caused abortion. The estimate was not statistically different from that obtained by direct questioning (34.1%, SE = 7.5%, binomial P value = 0.27, factor score = 1.32), suggesting that farmers did not hesitate to do the activity. Maasai conducted the risky behaviours against human infection such as drinking raw milk (P = 0.06) or blood (P < 0.01), and helping delivery with bear hands (P = 0.03) than the other tribes. The results showed that bovine brucellosis is endemic in agro-pastoral areas in Morogoro region, Tanzania. Veterinary service was a preventive factor of bovine brucellosis, suggested that regular preventive health measures may reduce the prevalence. The cattle farmers were willing to pay for brucellosis vaccination, particularly by limiting calves to be vaccinated, indicating the feasibility of community-based calf vaccination programme. Receiving education from veterinarians was again a key to accept vaccination for calves. Farmers were selling cows experienced abortion without hesitation, and this may have contributed to the maintenance of the disease but at the same time suppressed within-herd prevalence. This study showed that One Health approach for joint planning and actions of community-based brucellosis intervention, including health education, is necessary and feasible in Tanzania.ブルセラ病は世界中に広く蔓延している人獣共通感染症である。ブルセラ病は実際の発生数及び被害は甚大である一方、多くの途上国では政府による疾病制御は予算及び資源の不足により期待できない。本研究はタンザニアモロゴロ州における牛ブルセラ病の持続的かつ支払い可能な制御法の検討を目的に実施された。初回は横断研究により都市部と農業・放牧混合地域における牛ブルセラ病の有病率の比較及びリスク因子、ヒト感染に関わるリスク行動の調査研究を行った。牛の採血及び農家への質問票調査を実施した。牛血清の診断にはローズベンガル試験を用い、陽性サンプルにはC-ELISA を実施した。農場レベル有病率は都市部、農業・放牧混合地域でそれぞれ0.9% (1/106, 95% CI: 0.0–5.9%)、52.9% (9/17, 95% CI: 28.5–76.1%)であった。牛個体レベル調整有病率はそれぞれ0.2% (1/667, 95% CI: 0.0–1.1%)、7.0% (28/673, 95% CI: 5.7–8.4%)であった。農場レベルリスク因子は農場における牛の流産 (P < 0.01) 及び放牧 (P = 0.07) であった。ブルセラワクチンに関する知識のある農業・放牧混合地域の農家は皆無であり、同農家らはブルセラ病に関する知識が乏しく、生乳飲用(17.6%, P < 0.01 や牛血飲用(35.3%, P < 0.01)、牛の助産(100%, P = 0.04)等のヒト感染リスク行動を都市部農家と比較して有意に実施していた (各0%、0%、79.2%)。特に農業・放牧混合農家を対象としたヒト及び動物の健康に関する教育を通した介入プログラムの必要と考えられた。そこで、二回目の調査は農業放牧混合農家に焦点を当て、牛ブルセラ病の農場レベル有病率及びリスク因子、農家のブルセラ病制御に関する知識と行動を明らかにすることを目的として実施した。横断研究を用いI-ELISA によるバルク乳診断と質問票調査を124 農家に対して実施した。質問票にはブルセラ病に関わるリスク因子及び知識、ワクチン支払意欲及びItem Count Technique (ICT)法による流産牛売却行動の項目を設定した。調査農家のブルセラ病に関する知識は乏しかった (疾病名: 13.7%、症状: 3.2%、 牛からヒトへの伝染: 2.4%、ワクチン: 2.4%)。農場レベル有病率は44.4% (55/124, 95% CI: 35.5–53.5)であった。牛ブルセラ病リスク因子は無かったが、獣医サービスの利用が防除因子であった (OR = 0.39, 95%CI: 0.18—0.84, P = 0.02)。ワクチン支払について、すべての牛対象の場合59.7%、子牛のみ対象の場合89.5%の農家が受諾した。マサイ族はすべての牛対象のワクチン接種を有意に断る傾向がみられ (OR = 0.39, 95%CI: 0.19—0.83, P = 0.01)、獣医サービス利用農家は子牛のみ対象のワクチン接種を有意に受け入れる傾向がみられた (OR = 4.0, 95%CI: 1.2—13.0, P = 0.02)。ICT 法による解析では45.1%の農家が流産牛を市場に売却しており、直接質問による回答(34.1%, SE = 7.5%, binomial P value = 0.27, factor score = 1.32)と有意な差はみられず、売却行動に隠蔽性は無いと考えられた。マサイ族は生乳飲用 (P = 0.06)、牛血飲用 (P < 0.01)、素手による牛の助産 (P = 0.03)等のヒトブルセラ病感染リスク行動を他部族に比べ有意に取っていた。これらの結果から、タンザニア国モロゴロ州の農業・放牧混合地域では牛ブルセラ病は蔓延していることが分かった。獣医サービスは牛ブルセラ病の防除因子であり、継続的な制御・衛生対策が有病率を減少させる可能性が示された。農家の、特に子牛のみ対象の場合のワクチン支払意欲は高く、コミュニティ主体の子牛ワクチン接種プログラムの実現性が示された。獣医からの教育を受ける機会は、子牛ワクチン接種受け入れにも重要であることが分かった。また、農家は流産牛の市場への売却にためらいはなく、売却行動により他農場への感染を広げている可能性がある一方、農場内有病率を減少させている可能性も考えられた。本研究から、衛生教育を含めたコミュニティ主体によるブルセラ病介入プログラムの作成と実施のためのワンヘルスアプローチの必要性及び実行可能性が示された。酪農学園大

Seroprevalence and risk factors for human brucellosis in agro-pastoral areas in Tanzania

Background: Brucellosis is an endemic zoonosis in Tanzania. This study was conducted to investigate the seroprevalence of human brucellosis and its risk factors in agro-pastoral areas in Morogoro Region, Tanzania. Methods: Questionnaire survey and blood sampling were conducted from January to February 2018 at four villages. Anyone living in the villages and wished to participate were involved. Competitive ELISA was used for diagnosis. Risk factor analysis for sero-positivity in human and analysis for the association of sero-positivity between cattle and human within each farm were conducted, using the data of farm-level bovine brucellosis status from our bovine brucellosis research performed in 2016. Results: The seroprevalence was 33.3% (44/132). In univariable analysis, the Maasai were significantly more sero-positive (56.5%) than other tribes (28.4%) (OR = 3.23, 95% CI: 1.28–8.41). Drinking raw milk was a risk factor in both univariable and multivariable analyses (OR = 3.97, 95% CI: 1.61–10.20). A negative association between sero-positivity in cattle and human within each farm was found (p&lt;0.01). The Maasai performed more risk-taking behaviours for human infection than other tribes: drinking raw milk (p&lt;0.01) or blood (p&lt;0.01) and helping delivery of cattle with bare hands (p=0.03). Conclusions: The Maasai were at high risk of human brucellosis. More detailed survey and educational interventions are urgently needed

Diarrhea illness in livestock keeping households in Cambodia: An analysis using a One Health framework

BackgroundMost of human diarrheal pathogens are zoonotic, and transmission of the pathogens can occur by contaminated food, water, environment and direct contact with animals especially for livestock keepers. Yet little is known of the relative importance of different risk factors especially in under-studied countries. The objectives of this study were to identify risk factors for diarrhea in livestock keepers in Cambodia and detect diarrhea-causing pathogenic bacteria in both humans and livestock within a One Health approach. Of special interest were the links between diarrhea and food consumption and livestock-keeping.Materials and methodsWe used an existing dataset from a questionnaire survey conducted in 400 livestock farms in Prey Veng and Kampot Prefectures between February and March 2013 as well as laboratory results on bacterial isolation from fecal and swab samples from livestock and poultry, and human stool samples. Laboratory results were available for up to three animals of each species kept by a household, and for up to three human samples from households reporting at least one case of human diarrhea in the previous 2 weeks. Presence of Escherichia coli, Shigella spp. and Salmonella spp. was investigated in both animal and human samples, in addition to Aeromonas spp., Vibrio spp. and Plesiomonas spp. in animal samples and Campylobacter spp. in human samples. Univariable and multivariable risk factor analyses were performed by generalized linear mixed model.ResultsHousehold-level diarrhea incidence rate was 9.0% (36/400). The most statistically significant factor associated with diarrhea in multivariable analysis was water treatment for drinking and cooking (OR = 0.33, 95%CI: 0.16–0.69, p = 0.003), followed by number of days consuming egg within 2 weeks (OR = 1.16, 95%CI: 1.04–1.29, p = 0.008), number of children under 5 years old (OR = 1.99, 95%CI: 1.14–3.49, p = 0.016) and keeping poultry (OR = 0.36, 95%CI: 0.14–0.92, p = 0.033). Animal samples for bacterial culture test were collected at 279 cattle, 165 pig and 327 poultry farms, and bacteria were detected from 6 farms with the isolation of Escherichia coli O157 (non H7) from 1 cattle and 1 pig sample, Aeromonas caviae from 1 pig sample and Salmonella spp. from 3 chicken samples. In human samples, 17 out of 67 individual samples were positive for the culture test, detecting Escherichia coli O157 (non H7) from 7 samples and Shigella spp. from 10 samples. None of the households where target bacteria were detected from animal samples had human samples collected due to lack of diarrhea episodes in the household.ConclusionsIt has often been hypothesized that keeping livestock may increase the incidence of diarrhea through multiple pathways. Contrary to this, we found livestock-keeping was not associated with increased risk, but food-related behavior and children under 5 years of age were strongly associated with increased risk. We discuss mediating and confounding factors and make recommendations for reducing the burden of diarrheal disease in Cambodia and more widely in low- and middle-income countries

Diarrhea illness in livestock keeping households in Cambodia: An analysis using a One Health framework

Background: Most of human diarrheal pathogens are zoonotic, and transmission of the pathogens can occur by contaminated food, water, environment and direct contact with animals especially for livestock keepers. Yet little is known of the relative importance of different risk factors especially in under-studied countries. The objectives of this study were to identify risk factors for diarrhea in livestock keepers in Cambodia and detect diarrhea-causing pathogenic bacteria in both humans and livestock within a One Health approach. Of special interest were the links between diarrhea and food consumption and livestock-keeping. Materials and methods: We used an existing dataset from a questionnaire survey conducted in 400 livestock farms in Prey Veng and Kampot Prefectures between February and March 2013 as well as laboratory results on bacterial isolation from fecal and swab samples from livestock and poultry, and human stool samples. Laboratory results were available for up to three animals of each species kept by a household, and for up to three human samples from households reporting at least one case of human diarrhea in the previous 2 weeks. Presence of Escherichia coli, Shigella spp. and Salmonella spp. was investigated in both animal and human samples, in addition to Aeromonas spp., Vibrio spp. and Plesiomonas spp. in animal samples and Campylobacter spp. in human samples. Univariable and multivariable risk factor analyses were performed by generalized linear mixed model. Results: Household-level diarrhea incidence rate was 9.0% (36/400). The most statistically significant factor associated with diarrhea in multivariable analysis was water treatment for drinking and cooking (OR = 0.33, 95%CI: 0.16–0.69, p = 0.003), followed by number of days consuming egg within 2 weeks (OR = 1.16, 95%CI: 1.04–1.29, p = 0.008), number of children under 5 years old (OR = 1.99, 95%CI: 1.14–3.49, p = 0.016) and keeping poultry (OR = 0.36, 95%CI: 0.14–0.92, p = 0.033). Animal samples for bacterial culture test were collected at 279 cattle, 165 pig and 327 poultry farms, and bacteria were detected from 6 farms with the isolation of Escherichia coli O157 (non H7) from 1 cattle and 1 pig sample, Aeromonas caviae from 1 pig sample and Salmonella spp. from 3 chicken samples. In human samples, 17 out of 67 individual samples were positive for the culture test, detecting Escherichia coli O157 (non H7) from 7 samples and Shigella spp. from 10 samples. None of the households where target bacteria were detected from animal samples had human samples collected due to lack of diarrhea episodes in the household. Conclusions: It has often been hypothesized that keeping livestock may increase the incidence of diarrhea through multiple pathways. Contrary to this, we found livestock-keeping was not associated with increased risk, but food-related behavior and children under 5 years of age were strongly associated with increased risk. We discuss mediating and confounding factors and make recommendations for reducing the burden of diarrheal disease in Cambodia and more widely in low- and middle-income countries

The nucleoprotein is responsible for intracerebral pathogenicity of A/duck/Mongolia/47/2001 (H7N1) in chicks

Avian influenza viruses, A/duck/Mongolia/47/2001 (H7N1) (47/01) and A/duck/Mongolia/867/2002 (H7N1) (867/02), were defined as low pathogenic avian influenza viruses (LPAIVs) by intravenous pathogenicity test in chickens. On the other hand, the intracerebral pathogenicity indices of 47/01 and 867/02 were 1.30 and 0.00, respectively. A series of reassortant viruses were generated between 47/01 and 867/02, and their intracerebral pathogenicity was compared in one-day-old chicks to identify the protein(s) responsible for the intracerebral pathogenicity of 47/01. The results indicate that the amino acid positions at 50 and 98 of the nucleoprotein are related to the pathogenicity of 47/01 in chicks by intracerebral inoculation. A significant association was found between mortality of the chicks inoculated intracerebrally with 47/01 and virus replication in the lungs and/or brains. These results indicate that the NP of avian influenza viruses may be responsible for intracerebral pathogenicity in hosts