Assessment of the control measures for category A diseases of Animal Health Law: Contagious Caprine Pleuropneumonia

Assessing complexity and dynamics in epidemics: geographical barriers and facilitators of foot-and-mouth disease dissemination

Introduction

Physical and non-physical processes that occur in nature may influence biological processes, such as dissemination of infectious diseases. However, such processes may be hard to detect when they are complex systems. Because complexity is a dynamic and non-linear interaction among numerous elements and structural levels in which specific effects are not necessarily linked to any one specific element, cause-effect connections are rarely or poorly observed.

Methods

To test this hypothesis, the complex and dynamic properties of geo-biological data were explored with high-resolution epidemiological data collected in the 2001 Uruguayan foot-and-mouth disease (FMD) epizootic that mainly affected cattle. County-level data on cases, farm density, road density, river density, and the ratio of road (or river) length/county perimeter were analyzed with an open-ended procedure that identified geographical clustering in the first 11 epidemic weeks. Two questions were asked: (i) do geo-referenced epidemiologic data display complex properties? and (ii) can such properties facilitate or prevent disease dissemination?

Results

Emergent patterns were detected when complex data structures were analyzed, which were not observed when variables were assessed individually. Complex properties-including data circularity-were demonstrated. The emergent patterns helped identify 11 counties as 'disseminators' or 'facilitators' (F) and 264 counties as 'barriers' (B) of epidemic spread. In the early epidemic phase, F and B counties differed in terms of road density and FMD case density. Focusing on non-biological, geographical data, a second analysis indicated that complex relationships may identify B-like counties even before epidemics occur.

Discussion

Geographical barriers and/or promoters of disease dispersal may precede the introduction of emerging pathogens. If corroborated, the analysis of geo-referenced complexity may support anticipatory epidemiological policies.

Assessment of the control measures of the Category A diseases of the Animal Health Law: prohibitions in restricted zones and risk-mitigating treatments for products of animal origin and other materials

EFSA received a mandate from the European Commission to assess the effectiveness of prohibitions of certain activities in restricted zones, and of certain risk mitigation treatments for products of animal origin and other materials with respect to diseases included in the Category A list in the Animal Health Law (Regulation (EU) 2016/429). This opinion belongs to a series of opinions where other disease-specific control measures have been assessed. In this opinion, EFSA and the AHAW Panel of experts review the effectiveness of (i) prohibiting the movements of certain products, notably germinal products (semen, oocytes, embryos and hatching eggs), products of animal origin and animal by-products and feed of plant origin, hay and straw, and (ii) risk mitigation treatments for products of animal origin. In terms of semen, oocytes, embryos and hatching eggs, it was agreed that there was a lack of evidence particularly for embryos and oocytes reflected in a varying degree of uncertainty, whether these commodities could potentially contain the pathogen under consideration. The scenario assessed did not consider whether the presence of pathogen would lead to infection in the recipient animal. In terms of animal products, certain animal by-products and movement of feed of plant origin and straw, the assessment considered the ability of the commodity to transmit disease to another animal if exposed. For most pathogens, products were to some degree considered a risk, but lack of field evidence contributed to the uncertainty, particularly as potential exposure of ruminants to meat products is concerned. In terms of the risk mitigating treatments, recommendations have been made for several of these treatments, because the treatment description is not complete, the evidence is poor or inconclusive, or the evidence points to the treatment being ineffective.