An assessment of shedding with the oral rabies virus vaccine strain SPBN GASGAS in target and non-target species.

A safety requirement for live vaccines is investigating possible shedding in recipients since the presence of replication competent vaccine in secretions could result in direct and indirect horizontal transmission. This is especially relevant for oral rabies vaccine baits that are deliberately distributed into the environment. In the current study, survival of an oral rabies virus vaccine, SPBN GASGAS, was examined in excretions from different target and non-target species; red fox, raccoon dog, small Indian mongoose, raccoon, striped skunk, domestic dog, domestic cat and domestic pig. Saliva - and (pooled) fecal samples collected at different time points after oral administration of the vaccine strain were examined for the presence of viral RNA (rt-PCR). All PCR-positive and a subset of PCR-negative samples were subsequently investigated for the presence of infectious virus by isolation in cell culture (RTCIT). Up to 7 days post vaccine administration viral RNA could be detected in 50 of 758 fecal samples but no infectious virus was detected in any of the examined PCR-positive fecal samples. In contrast, RNA-fragments were detected in 248 of 1053 saliva swabs for an extended period (up to 10 days) after vaccine administration, but viable virus was only present during the first hours post vaccine administration in 38 samples. No infectious vaccine virus was isolated in saliva swabs taken 24 h or more after vaccine administration. Hence, no active shedding of the vaccine virus SPBN GASGAS after oral administration occurred and the virus isolated during the initial hours was material originally administered and not a result of virus replication within the host. Thus, potential horizontal transmission of this vaccine virus is limited to a short period directly after vaccine bait uptake. It can be concluded that the environmental risks associated with shedding after distributing vaccine baits containing SPBN GASGAS are negligible.

Estimating the global burden of endemic canine rabies.

BACKGROUND: Rabies is a notoriously underreported and neglected disease of low-income countries. This study aims to estimate the public health and economic burden of rabies circulating in domestic dog populations, globally and on a country-by-country basis, allowing an objective assessment of how much this preventable disease costs endemic countries. METHODOLOGY/PRINCIPAL FINDINGS: We established relationships between rabies mortality and rabies prevention and control measures, which we incorporated into a model framework. We used data derived from extensive literature searches and questionnaires on disease incidence, control interventions and preventative measures within this framework to estimate the disease burden. The burden of rabies impacts on public health sector budgets, local communities and livestock economies, with the highest risk of rabies in the poorest regions of the world. This study estimates that globally canine rabies causes approximately 59,000 (95% Confidence Intervals: 25-159,000) human deaths, over 3.7 million (95% CIs: 1.6-10.4 million) disability-adjusted life years (DALYs) and 8.6 billion USD (95% CIs: 2.9-21.5 billion) economic losses annually. The largest component of the economic burden is due to premature death (55%), followed by direct costs of post-exposure prophylaxis (PEP, 20%) and lost income whilst seeking PEP (15.5%), with only limited costs to the veterinary sector due to dog vaccination (1.5%), and additional costs to communities from livestock losses (6%). CONCLUSIONS/SIGNIFICANCE: This study demonstrates that investment in dog vaccination, the single most effective way of reducing the disease burden, has been inadequate and that the availability and affordability of PEP needs improving. Collaborative investments by medical and veterinary sectors could dramatically reduce the current large, and unnecessary, burden of rabies on affected communities. Improved surveillance is needed to reduce uncertainty in burden estimates and to monitor the impacts of control efforts.

Control and prevention of canine rabies: the need for building laboratory-based surveillance capacity.

Dogs are the source of more than 99% of human rabies virus infections in endemic regions. Without postexposure prophylaxis, almost all cases are fatal, making rabies the most lethal infectious disease. Tens of thousands of deaths are reported annually, but the official figures are believed to be gross underestimates. Controlling canine rabies, especially in free-ranging dogs, is the first priority to reduce the burden of human disease. Because of their limited medical infrastructure, most endemic countries lack the laboratory facilities needed to diagnose human cases of viral encephalitis. Moreover, the veterinary sectors are often unable to undertake systematic surveillance and reporting of rabies in animals. Without an adequate and functioning risk assessment system that is primed for use, rabies will remain a 'neglected' and omnipresent disease, especially in poverty-stricken regions of the world. Fortunately, experience with the elimination of canine rabies from many industrialized countries has shown that these barriers are not insurmountable. Successful rabies prevention and control strategies that prove the absence of the disease depend on laboratory-based surveillance, rapid data reporting and an adequate system of risk assessment. Future control and prevention programmes should therefore coordinate the development of these key factors, creating synergies to eliminate rabies at its animal source. This article forms part of a symposium in Antiviral Research on the global elimination of canine rabies.

Elimination of terrestrial rabies in Germany using oral vaccination of foxes.

Oral rabies vaccination (ORV) has become the method of choice in fox rabies control in Europe. During the past three decades fox-mediated rabies virtually disappeared from Western and Central Europe. Following Switzerland, Germany was the second European country to launch ORV field trials on its territory in 1983. This paper provides a historical overview on the emergence of fox rabies in Germany; describing the basic principles and milestones of the German rabies eradication programme and presenting results of two decades of efforts to control the disease in foxes. Also, setbacks as well as country-specific differences and particularities on Germany's long way to rabies elimination in comparison to other European countries are addressed. Since the first field trials in Germany the number of rabies cases steadily decreased from 10 484 in 1983 to three cases recorded in 2006. On February 3rd 2006 the last case of terrestrial rabies in Germany was detected in a fox near the town of Mainz, Rhineland-Palatinate. In 2008, ORV ceased after 25 years and Germany was officially declared as free from terrestrial rabies. The German rabies eradication programme did cost approximately 100 million euro of which 37 million euro were covered by the EU. For the future, efforts should focus on maintaining a rabies free status by implementing measures to prevent reintroduction of terrestrial rabies from endemic countries.

Oral vaccination of foxes against rabies in Turkey between 2008 and 2010.

Following a sustained spill-over event from dogs to foxes, fox rabies spread rapidly in the Aegean region, Turkey. In order to control the outbreak a program of oral vaccination of foxes against rabies was introduced. In the selected vaccination area three annual campaigns between 2008 and 2010 were undertaken during the winter months whereby the vaccine baits were distributed exclusively by plane using a density of 18 baits per km2. Subsequently, fox rabies cases were reported only from locations bordering the non-vaccinated areas. Hence, it was shown that fox rabies control by means of oral rabies vaccination is feasible in Turkey. However, for the progress towards the elimination of fox-mediated rabies in Turkey to be maintained, it is necessary that political and financial support is secured to extend oral vaccination where infected foxes remain.

Assessment of the human medical significance of the rabies zoonosis in Germany--analysis of available data and desiderata.

In order to assess the human medical significance of the rabies zoonosis in Germany, the data of the relevant surveillance and of the registration systems as well as prescriptions submitted to the statutory health insurance (SHI) were assessed. In all, 2441 of the 81 280 total examinations for rabies conducted on animals were performed subsequent to contact with humans. In this context 54% of exposures were attributed to wild animals and 46%, to domestic animals. In 2006 and 2007 there were still 0.42 and 0.34 veterinary medical analyses per 100 000 inhabitants, respectively, subsequent to human contact. After the proclamation that Germany was free of terrestrial rabies, these indices dropped to 0.2 in 2009 and 2010. During the survey period, 21 700 doses of rabies vaccine were issued annually for SHI prescriptions on average; they would have been adequate for approximately 7230 complete courses of rabies pre-exposure prophylaxis or 4340 complete post-exposure treatments. For which of these two principal indications the vaccines were actually used cannot be determined from the SHI prescriptions. Taken together, the officially available data from rabies surveillance or registration systems even in combination with a nearly complete record of SHI prescription numbers did not allow an even nearly adequate reconstruction of the human medical significance of the rabies zoonosis in Germany. If one desired to achieve this, one would have to use, for example, an approach that is known from other European countries such as France, Finland, or The Netherlands.

Assessment of inactivated human rabies vaccines: biochemical characterization and genetic identification of virus strains.

The World Health Organization (WHO) recommends the periodic evaluation of the purity of the cell lines used in the production of rabies vaccines, as well as the antigenic identity of the virus strains. Here, we analyzed seventeen marketed inactivated human rabies virus vaccines for viral and non-viral proteins by SDS-PAGE and Coomassie/silver staining. Mass spectrometric analysis of an abundant 60-70 kDa signal indicated that in most vaccines serum albumin of human origin (HSA) was the major component. Quantification of HSA in the vaccines revealed a mean concentration of 22 mg HSA/dose in all tested PVRV (purified vero cell rabies vaccine), HDCV (human diploid cell rabies vaccine) and PHK (primary hamster kidney) vaccines. In contrast, 1000-fold lower HSA levels and no HSA were detected in PCECV (purified chick embryo cell-culture vaccine) and PDEV (duck embryo rabies vaccine), respectively. Western blot analyses further confirmed a high bias in the HSA content, whereas the virus protein levels were rather similar in all tested vaccines. In addition, the vaccine viruses were sequenced within the N- and G-genes to identify the strain. In the majority of sequenced vaccines, the declared vaccine strain was confirmed. However, some discrepancies in the genetic identification were observed, supporting WHO's recommendation for the molecular characterization of vaccine seed strains. This research highlights the variation in purity found between different human rabies virus vaccines, and suggests that further research is needed to establish the impact non-active components have on the potency of such vaccines.

Development of a mouse monoclonal antibody cocktail for post-exposure rabies prophylaxis in humans.

As the demand for rabies post-exposure prophylaxis (PEP) treatments has increased exponentially in recent years, the limited supply of human and equine rabies immunoglobulin (HRIG and ERIG) has failed to provide the required passive immune component in PEP in countries where canine rabies is endemic. Replacement of HRIG and ERIG with a potentially cheaper and efficacious alternative biological for treatment of rabies in humans, therefore, remains a high priority. In this study, we set out to assess a mouse monoclonal antibody (MoMAb) cocktail with the ultimate goal to develop a product at the lowest possible cost that can be used in developing countries as a replacement for RIG in PEP. Five MoMAbs, E559.9.14, 1112-1, 62-71-3, M727-5-1, and M777-16-3, were selected from available panels based on stringent criteria, such as biological activity, neutralizing potency, binding specificity, spectrum of neutralization of lyssaviruses, and history of each hybridoma. Four of these MoMAbs recognize epitopes in antigenic site II and one recognizes an epitope in antigenic site III on the rabies virus (RABV) glycoprotein, as determined by nucleotide sequence analysis of the glycoprotein gene of unique MoMAb neutralization-escape mutants. The MoMAbs were produced under Good Laboratory Practice (GLP) conditions. Unique combinations (cocktails) were prepared, using different concentrations of the MoMAbs that were capable of targeting non-overlapping epitopes of antigenic sites II and III. Blind in vitro efficacy studies showed the MoMab cocktails neutralized a broad spectrum of lyssaviruses except for lyssaviruses belonging to phylogroups II and III. In vivo, MoMAb cocktails resulted in protection as a component of PEP that was comparable to HRIG. In conclusion, all three novel combinations of MoMAbs were shown to have equal efficacy to HRIG and therefore could be considered a potentially less expensive alternative biological agent for use in PEP and prevention of rabies in humans.