Celovita kvantitativna ocena tveganja za prisotnost Mycobacterium avium subsp. paratuberculosis v mleku in mlečnih izdelkih

Knific, Tanja (avtor), Ocepek, Matjaž (mentor), Kirbiš, Andrej (komentor)

Cilj disertacije je bil oceniti tveganje za izpostavljenost bakteriji Mycobacterium avium subsp. paratuberculosis (MAP) preko mleka in mlečnih izdelkov za slovenskega potrošnika. Domneva se, da je MAP lahko povezana s Crohnovo boleznijo in nekaterimi drugimi kroničnimi boleznimi ljudi. Čeprav vzročnost še ni bila dokazana, je pomembno izboljšati razumevanje tveganja za izpostavljenost. Glavni vir MAP za ljudi je najverjetneje govedo. MAP pri govedu povzroča paratuberkulozo ali Johne-jevo bolezen, ki zmanjšuje ekonomsko učinkovitost govedoreje po vsem svetu. Zaradi pomanjkanja empiričnih podatkov smo razvili dva modela za pridobitev podatkov o možnem epidemiološkem stanju v sektorju mleka v Sloveniji. S stohastičnim razrednim modelom smo preučili širjenje MAP v tipični slovenski čredi krav molznic. Z modeliranjem širjenja MAP na časovnem omrežju s tako imenovanim SI modelom (angl. susceptible-infectious; dovzeten-inficiran) in štirih scenarijev verjetnosti prenosa MAP pa smo ocenili možno prevalenco. Pridobljene rezultate smo uporabili v modelu kvantitativne ocene tveganja s simulacijami Monte Carlo za oceno možne izpostavljenosti človeka bakteriji MAP preko mleka in mlečnih izdelkov. Poleg tega smo izvedli analizo omrežja premikov goveda v Sloveniji, da bi ocenili možnost izvajanja ciljanih intervencijskih ukrepov. Rezultati kažejo, da analiza omrežja lahko nudi podporo pri optimizaciji nadzora paratuberkuloze v Sloveniji. V nasprotju z našo hipotezo je razredni model pokazal podobno razširjenost MAP znotraj črede, kot so ocenile predhodne raziskave v Sloveniji. Z upoštevanjem danih predpostavk in negotovosti smo ocenili, da je splošno tveganje za izpostavljenost MAP preko mleka in mlečnih izdelkov za slovenskega potrošnika majhno. Kvantitativno oceno izpostavljenosti smo izvedli za surovo mleko, pasterizirano polnomastno mleko in mleko, obdelano pri ultra visoki temperaturi, vendar menimo, da se lahko rezultati do neke mere prenesejo tudi na druge mlečne izdelke na zadevni ravni proizvodnje. Za ljudi, ki uživajo surovo mleko in surove mlečne izdelke s kmetij s paratuberkulozo, je tveganje za izpostavljenost MAP visoko. Vendar je bila simulirana količina MAP na liter surovega mleka v rezervoarju za mleko na kmetiji nizka. Pomembno je poudariti, da je tveganje za izpostavljenost MAP preko pasteriziranega mleka v maloprodaji in preko drugega predelanega mleka najverjetneje zanemarljivo. Naši rezultati bi lahko nudili podporo za informirano odločanje o intervencijskih ukrepih za nadzor MAP v Sloveniji. V primeru, da bo povezava med MAP in boleznimi pri človeku potrjena, lahko naša raziskava služi kot dober začetek prizadevanj za zmanjšanje tveganja. Dobljeni rezultati so lahko uporabni tudi za druge države, ki imajo podobno strukturo mlečnih gospodarstev.

• Jezik: Slovenski jezik
• Ključne besede: Bolezni goveda, epidemiologija, ocena tveganja, metode, paratuberkuloza, prenos, epidemiologija, prevalenca, Mycobacterium avium subsp. paratuberculosis, mleko, mikrobiologija, varnost živil, biološki modeli
• Vrsta gradiva: Doktorsko delo/naloga
• Organizacija: VF - Veterinarska fakulteta
• Leto izida: 2020
• PID: 20.500.12556/RUL-125165
• Datum objave v RUL: 05.03.2021

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Comprehensive quantitative risk assessment on the presence of Mycobacterium avium subsp. paratuberculosis in milk and milk products

Izvleček

The objective of this thesis was to assess the risk of exposure to Mycobacterium avium subsp. paratuberculosis (MAP) via milk and milk products for the Slovenian consumer. MAP is suspected to be linked to Crohn’s disease and some other chronic human diseases. Although causality has not yet been confirmed, it is important to improve the understanding of the risk of human exposure. Cattle are believed to be the main source of MAP for humans. In cattle, MAP causes paratuberculosis or Johne’s disease, a worldwide endemic disease with large economic consequences. Due to the lack of empirical data, we applied two models as tools for obtaining data on the epidemiological situation of MAP, specific for the Slovenian dairy sector. A stochastic compartmental model was developed to study the within-herd spread of MAP in a typical Slovenian dairy herd and a susceptible-infectious model on the temporal network of cattle movements to estimate the prevalence of MAP using four different scenarios for probabilities of transmission. The obtained results were used in the quantitative risk assessment model with Monte Carlo simulations to assess possible human exposure to MAP via milk and milk products. Additionally, network analysis of Slovenian cattle movements was performed to estimate the prospect of targeted MAP intervention measures. The results suggest that network analysis may provide support in the optimization of paratuberculosis control in Slovenia. The compartmental model showed a similar within-herd prevalence of MAP in Slovenia as was previously estimated, which was opposite to what we hypothesized. Concerning the underlying assumptions and uncertainties, we estimated that the overall risk of exposure to MAP via milk and milk products for the Slovenian consumer is low. The quantitative exposure assessment was performed for raw milk, pasteurised whole milk and ultra-high temperature treated milk; nevertheless, we believe that the results can be extended, at least in part, to other milk products at the respective level of production. For people consuming raw milk and raw milk products from farms with paratuberculosis, the risk of exposure to MAP is high. However, the simulated amount of MAP per litre of raw bulk tank milk was low. It is important to emphasise that the risk of exposure to MAP via pasteurised retail milk and via other processed milk is most likely insignificant. Our results could provide support for informed decision-making in MAP intervention measures in Slovenia and in case the link between MAP and human diseases is confirmed also as a start for possible risk mitigation efforts. These results could be applicable to other countries with a similar dairy farm structure.

• Ključne besede: Cattle diseases, epidemiology, risk assessment, methods, paratuberculosis, transmission, epidemiology, prevalence, Mycobacterium avium subsp. paratuberculosis, milk, microbiology, food safety, biological models