Vaccination control programs for multiple livestock host species: an age-stratified, seasonal transmission model for brucellosis control in endemic settings

Brucella melitensis causes production losses in ruminants and febrile disease in humans in Africa, Central Asia, the Middle East and elsewhere. Although traditionally understood to affect primarily sheep and goats, it is also the predominant Brucella species that affects cows in some endemic areas. Despite this, no licensed vaccine is available specifically for use against B. melitensis in cows. The mainstay of most control programs is vaccination of sheep and goats with a live vaccine, Rev-1. The aim of this study was to investigate how critical vaccination of cows might be, in order to control B. melitensis on a mixed sheep-and-cattle farm

Past and Ongoing Tsetse and Animal Trypanosomiasis Control Operations in Five African Countries: A Systematic Review

Background Control operations targeting Animal African Trypanosomiasis and its primary vector, the tsetse, were covering approximately 128,000 km2 of Africa in 2001, which is a mere 1.3% of the tsetse infested area. Although extensive trypanosomiasis and tsetse (T&T) control operations have been running since the beginning of the 20th century, Animal African Trypanosomiasis is still a major constraint of livestock production in sub-Saharan Africa. Methodology/Principal Findings We performed a systematic review of the existing literature describing T&T control programmes conducted in a selection of five African countries, namely Burkina Faso, Cameroon, Ethiopia, Uganda and Zambia, between 1980 and 2015. Sixty-eight documents were eventually selected from those identified by the database search. This was supplemented with information gathered through semi-structured interviews conducted with twelve key informants recruited in the study countries and selected based on their experience and knowledge of T&T control. The combined information from these two sources was used to describe the inputs, processes and outcomes from 23 major T&T control programmes implemented in the study countries. Although there were some data gaps, involvement of the target communities and sustainability of the control activities were identified as the two main issues faced by these programmes. Further, there was a lack of evaluation of these control programmes, as well as a lack of a standardised methodology to conduct such evaluations. Conclusions/Significance Past experiences demonstrated that coordinated and sustained control activities require careful planning, and evidence of successes, failures and setbacks from past control programmes represent a mine of information. As there is a lack of evaluation of these programmes, these data have not been fully exploited for the design, analyses and justification of future control programmes

Systematic review of brucellosis in the Middle East: disease frequency in ruminants and humans and risk factors for human infection

This paper considers the problem of finding global states incoming to a specified global state in a Boolean network, which may be useful for pre-processing of finding a sequence of control actions for a Boolean network and for identifying the basin of attraction for a given attractor, We show that this problem is NP-hard in general along with related theoretical results, On the other hand, we present algorithms that are much faster than the naive exhaustive search-based algorithm. ©2007 IEEE.link_to_subscribed_fulltex

Assessment of the risk of Hepatitis E virus occurrence in pork carcasses at slaughter in the UK

Hepatitis E virus (HEV) is a RNA virus of the genus Hepevirus. HEV genotype 3 is zoonotic and pigs are the main reservoir. This genotype has been identified in the United Kingdom, in sporadic locally-acquired cases without recent history of foreign travel to endemic countries. The number of HEV-confirmed human cases in the UK has increased significantly, from 124 cases in 2003 to 661 in 2013. Non-travel cases now account for the majority (69%) of cases observed annually in the UK. Our aim was to assess the risk of HEV occurrence in pork carcases at slaughter in the UK. We performed a quantitative exposure assessment using Monte Carlo simulation to estimate the number of carcasses contaminated with HEV produced in a high throughput porcine abattoir during one year. The input data used were: a) true prevalence in British pigs, b) probability of viral shedding in bile and faeces c) number of pig carcases with bile and/or faecal contamination detected during post-mortem inspection. The following assumptions were made when data were unavailable: a) sensitivity and specificity of the RP-PCR diagnostic test; b) meat from viraemic pigs was considered HEV-positive; c) visual faecal and bile contamination only considered since microscopic contamination would not be detected through visual inspection. We estimated through our model that 175,152 (2.4%) of carcases produced in high throughput abattoirs would be infected with HEV in one year period. The number of viraemic pigs slaughtered at the abattoir was the largest driver of the uncertainty in carcass contamination. Variations in this parameter would change the output from 62,982 carcasses up to 306,320. Mitigation strategies at farm level should be explored, as it appears that control at this level would likely result in a higher reduction in HEV contamination in pork meat