A Quantitative Risk Assessment for Bovine Spongiform Encephalopathy in Japan

Abstract

A predictive case-cohort model was applied to Japanese data to analyze the interaction between challenge and stability factors for bovine spongiform encephalopathy (BSE) for the period 1985-2020. BSE risk in cattle was estimated as the expected number of detectable cases per year. The model was comprised of a stochastic spreadsheet calculation model with the following inputs: (1) the origin and quantity of live cattle and meat and bone meal imported into Japan, (2) the age distribution of native cattle, and (3) the estimated annual basic reproduction ratio (R(0) ) for BSE. The estimated probability of having zero detectable cases in Japan in 2015 was 0.90 (95% CI 0.83-0.95). The corresponding value for 2020 was 0.99 (95% CI 0.98-0.99). The model predicted that detectable cases may occur in Japan beyond 2015 because of the assumption that continued transmission was permitted to occur (albeit at a very low level) after the 2001 ban on the importation and domestic use of all processed animal proteins for the production of animal feed and for fertilizer. These results reinforce the need for animal health authorities to monitor the efficacy of control measures so that the future course of the BSE epidemic in Japan can be predicted with greater certainty.

Quarantine Regulations and the Impact of Modern Detection Methods

“…The best approach to minimize the impact of pests and diseases is to contain the organism at the center of origin. This is true independent of host, geography, or timing, from the Ebola viruses in Africa (10) to bovine spongiform encephalopathy in Europe (63) and late blight in Mexico (45,89). Such cases affecting humans, livestock, and plants provide excellent examples as to why quarantine regulations have been developed across the globe.…”

Prevention and control of zoonoses at their source: from the Chinese perspective

“…In recent years, mad cow disease (bovine spongiform encephalopathy) from the UK and other European countries has appeared in Japan, Korea, Hong Kong, Taiwan and other countries near China [39][40][41]. Hang-Nipah encephalitis, first reported in Australia in 1994, appeared in Malaysia in 1998 and then in Bangladesh in 2001, with continuing outbreaks in recent years and an associated mortality rate as high as 74%.…”