Rabies Virus in Sierra Leone: Challenges and Recommended Solutions for Elimination by 2030

The objective of this write-up is to find possible solution control canine rabies virus in Sierra Leone and other low-income countries in the world. Rabies is a viral disease affecting both humans and animals in Sierra Leone. The country has no policy on dog ownership and management, two veterinarians, limited access to rabies vaccines and human immunoglobin, and a lack of information about the disease in the country despite increasing dog bite cases and death. There is no wildlife specialist to initiate wildlife vaccination. Continuous vaccination increased awareness, trained personnel in veterinary and wildlife, development of policies on responsible dog ownership and by-laws and increase financial support from the government and private sector will help Sierra Leone eliminate rabies in the first half of the twenty-first century.

Bridging the gap: Using reservoir ecology and human serosurveys to estimate Lassa virus spillover in West Africa

Forecasting the risk of pathogen spillover from reservoir populations of wild or domestic animals is essential for the effective deployment of interventions such as wildlife vaccination or culling. Due to the sporadic nature of spillover events and limited availability of data, developing and validating robust, spatially explicit, predictions is challenging. Recent efforts have begun to make progress in this direction by capitalizing on machine learning methodologies. An important weakness of existing approaches, however, is that they generally rely on combining human and reservoir infection data during the training process and thus conflate risk attributable to the prevalence of the pathogen in the reservoir population with the risk attributed to the realized rate of spillover into the human population. Because effective planning of interventions requires that these components of risk be disentangled, we developed a multi-layer machine learning framework that separates these processes. Our approach begins by training models to predict the geographic range of the primary reservoir and the subset of this range in which the pathogen occurs. The spillover risk predicted by the product of these reservoir specific models is then fit to data on realized patterns of historical spillover into the human population. The result is a geographically specific spillover risk forecast that can be easily decomposed and used to guide effective intervention. Applying our method to Lassa virus, a zoonotic pathogen that regularly spills over into the human population across West Africa, results in a model that explains a modest but statistically significant portion of geographic variation in historical patterns of spillover. When combined with a mechanistic mathematical model of infection dynamics, our spillover risk model predicts that 897,700 humans are infected by Lassa virus each year across West Africa, with Nigeria accounting for more than half of these human infections.

A Perspective on Rabies in the Middle East—Beyond Neglect

Rabies is a neglected but preventable viral zoonosis that poses a substantial threat to public health. In this regard, a global program has been initiated for the elimination of human rabies caused by rabid dogs through the mass vaccination of canine populations. Geographic areas vary greatly towards attainment of this objective. For example, while dog-mediated and wildlife rabies have been largely controlled in major parts of the Americas and Western Europe, the Middle East still grapples with human rabies transmitted by unvaccinated dogs and cats. Rabies prevention and control in the Middle East is quite difficult because the region is transcontinental, encompassing portions of Africa, Asia, and Europe, while consisting of politically, culturally, and economically diverse countries that are often subject to war and unrest. Consequently, one over-riding dilemma is the misinformation or complete lack of rabies surveillance data from this area. This communication is an attempt to provide an overview of rabies in the Middle East, as a cohesive approach for the honing of disease management in each area, based on data compiled from multiple sources. In addition, the related regional transboundary movement of rabies was investigated through phylogenetic studies of available viral gene sequences. Thereafter, the epidemiological status of rabies was assessed for the region. Finally, localities were classified first by the Stepwise Approach towards Rabies Elimination framework and then categorized into four different groups based on management theme: “rabies free”; owned dog and domestic animal vaccination; community dog vaccination; and wildlife vaccination. The classification system proposed herein may serve as a baseline for future efforts. This is especially important due to the severe lack of rabies information available for the Middle East as a whole and a need for a comprehensive program focusing on the entirety of the region in light of renewed international commitment towards canine rabies elimination.

Estimating wildlife vaccination coverage using genetic methods

Vaccination is a potentially useful approach for the control of disease in wildlife populations. The effectiveness of vaccination is contingent in part on obtaining adequate vaccine coverage at the population level. However, measuring vaccine coverage in wild animal populations is challenging and so there is a need to develop robust approaches to estimate coverage and so contribute to understanding the likely efficacy of vaccination.We used a modified capture mark recapture technique to estimate vaccine coverage in a wild population of European badgers (Meles meles) vaccinated by live-trapping and injecting with Bacillus Calmette-Guérin as part of a bovine tuberculosis control initiative in Wales, United Kingdom. Our approach used genetic matching of vaccinated animals to a sample of the wider population to estimate the percentage of badgers that had been vaccinated. Individual-specific genetic profiles were obtained using microsatellite genotyping of hair samples which were collected both directly from trapped and vaccinated badgers and non-invasively from the wider population using hair traps deployed at badger burrows.We estimated the percentage of badgers vaccinated in a single year and applied this to a simple model to estimate cumulative vaccine coverage over a four year period, corresponding to the total duration of the vaccination campaign.In the year of study, we estimated that between 44-65% (95% confidence interval, mean 55%) of the badger population received a vaccine dose. Using the model, we estimated that 70-85% of the total population would have received at least one vaccine dose over the course of the four year vaccination campaign.This study represents the first application of this novel approach for measuring vaccine coverage in wildlife. This is also the first attempt at quantifying the level of vaccine coverage achieved by trapping and injecting badgers. The results therefore have specific application to bovine tuberculosis control policy, and the approach is of significance to the wider field of wildlife vaccination.

Assessment of an Oral Mycobacterium bovis BCG Vaccine and an Inactivated M. bovis Preparation for Wild Boar in Terms of Adverse Reactions, Vaccine Strain Survival, and Uptake by Nontarget Species

ABSTRACTWildlife vaccination is increasingly being considered as an option for tuberculosis control. We combined data from laboratory trials and an ongoing field trial to assess the risk of an oralMycobacterium bovisBCG vaccine and a prototype heat-inactivatedMycobacterium bovispreparation for Eurasian wild boar (Sus scrofa). We studied adverse reactions, BCG survival, BCG excretion, and bait uptake by nontarget species. No adverse reactions were observed after administration of BCG (n= 27) or inactivatedM. bovis(n= 21). BCG was not found at necropsy (175 to 300 days postvaccination [n= 27]). No BCG excretion was detected in fecal samples (n= 162) or in urine or nasal, oral, or fecal swab samples at 258 days postvaccination (n= 29). In the field, we found no evidence of loss of BCG viability in baits collected after 36 h (temperature range, 11°C to 41°C). Camera trapping showed that wild boar (39%) and birds (56%) were the most frequent visitors to bait stations (selective feeders). Wild boar activity patterns were nocturnal, while diurnal activities were recorded for all bird species. We found large proportions of chewed capsules (29%) (likely ingestion of the vaccine) and lost baits (39%) (presumably consumed), and the proportion of chewed capsules showed a positive correlation with the presence of wild boar. Both results suggest proper bait consumption (68%). These results indicate that BCG vaccination in wild boar is safe and that, while bait consumption by other species is possible, this can be minimized by using selective cages and strict timing of bait deployment.