Bovine rabies in Turkey: patterns of infection and implications for costs and control. Epidemiol Infect. 2014;142:1925-1933. [PMID: 24280252 DOI: 10.1017/s0950268813002811]

Oral rabies vaccination of foxes in Türkiye, 2019-2022

Background

Rabies in Turkey is maintained by dogs, but following a sustained spill-over, red fox mediated rabies had spread from the Aegean region to the central part of Türkiye. During the past four years from 2019 to 2023 large scale efforts used oral rabies vaccination (ORV) to control rabies in red foxes. Here, we present the results of the largest ORV campaign on the Asian continent.

Methods

ORV campaigns were carried out twice a year in spring and autumn with a targeted bait density of 20-23 baits/km2. Monitoring of ORV campaigns included the GIS-based analyses of bait distribution, the assessment of bait uptake through biomarker detection and the determination of seroconversion (sero-positivity in ELISA) in the target species collected within the vaccination area. For determination of fox rabies incidence in vaccination areas as the main indicator of the performance of the ORV campaigns, epidemiological data was obtained from the national passive surveillance program.

Results

Aerial bait distribution was highly accurate, with >99 % of baits being recorded from targeted zones, thus meeting the desired bait densities. Although the overall bait uptake (28.1 %; 95 %CI: 23.2-32.8) and seroprevalance (36.3 %; 95 %CI: 30.0-43.2) were low, rabies incidence drastically decreased in ORV areas and rabies was eliminated from western and central parts of Turkey, with no reported cases in foxes from ORV areas in 2022 and 2023.

Conclusions

A large-scale ORV campaign against fox rabies using high quality vaccine baits and the GIS-aided and monitored bait distribution was able to control fox mediated rabies in the western and central parts of Türkiye. Rabies control both in dogs and foxes should be expanded to cover also the eastern parts of Türkiye, to become eventually rabies free.

Patterns of Animal Rabies Prevalence in Northern South Africa between 1998 and 2022

Rabies is endemic in South Africa and rabies cycles are maintained in both domestic and wildlife species. The significant number of canine rabies cases reported by the World Organization for Animal Health Reference Laboratory for Rabies at Onderstepoort suggests the need for increased research and mass dog vaccinations on specific targeted foci in the country. This study aimed to investigate the spatiotemporal distribution of animal rabies cases from 1998 to 2017 in northern South Africa and environmental factors associated with highly enzootic municipalities. A descriptive analysis was used to investigate temporal patterns. The Getis-Ord Gi statistical tool was used to exhibit low and high clusters. Logistic regression was used to examine the association between the predictor variables and highly enzootic municipalities. A total of 9580 specimens were submitted for rabies diagnosis between 1998 and 2022. The highest positive case rates were from companion animals (1733 cases, 59.71%), followed by livestock (635 cases, 21.88%) and wildlife (621 cases, 21.39%). Rabies cases were reported throughout the year, with the majority occurring in the mid-dry season. Hot spots were frequently in the northern and eastern parts of Limpopo and Mpumalanga. Thicket bush and grassland were associated with rabies between 1998 and 2002. However, between 2008 and 2012, cultivated commercial crops and waterbodies were associated with rabies occurrence. In the last period, plantations and woodlands were associated with animal rabies. Of the total number of municipalities, five consistently and repeatedly had the highest rabies prevalence rates. These findings suggest that authorities should prioritize resources for those municipalities for rabies elimination and management.

Comparing the genetic typing methods for effective surveillance and rabies control in Georgia

A full nucleoprotein gene sequencing of 68 isolates collected from passive rabies surveillance system in Georgia between 2015 and 2016 identified two distinct dog rabies phylogroups, GEO_V1 and GEO_V2, which both belonged to the cosmopolitan dog clade. GEO_V1 was found throughout the country and was further divided into four sub-phylogroups that overlapped geographically; GEO_V2 was found in the southeast region and was closely related to dog rabies in Azerbaijan. A sequence analysis of the full N gene, partial nucleoprotein gene of N-terminal and C-terminal, and the amplicon sequences of pan-lyssavirus RT-qPCR LN34 showed that all four sequencing approaches provided clear genetic typing results of canine rabies and could further differentiate GEO_V1 and GEO_V2. The phylogenetic analysis results vary and were affected by the length of the sequences used. Amplicon sequencing of the LN34 assay positive samples provided a rapid and cost-effective method for rabies genetic typing, which is important for improving rabies surveillance and canine rabies eradication globally.

Preventable public health challenge: Rabies suspected exposure and prophylaxis practices in southwestern of Turkey

BACKGROUND

Rabies is found in many countries of the eastern Mediterranean and is one of the most important zoonotic diseases in the world. The study aims to describe rabies suspected exposures (RSE) and rabies prophylaxis practices in Antalya-Turkey between 2010 and 2013.

METHODS

All 2513 RSE cases presenting to a rabies vaccination center in Antalya, southwestern Turkey, were retrospectively investigated.

RESULTS

The mean age of the RSE cases was 30.04±19.63 years with male predominance (63.6%). The vast majority was from urban areas (91.7%), and a postexposure rabies vaccination program was applied to 79.7% of participants. Dogs were the primary source of RSE cases (61.2%). The 39.2% of animals were under observation, and 9.53% of them died. Forty-two animals (1.7%) were laboratory confirmed rabid; 61.9% of them were cows. The rabid animal rate in the rural area was significantly higher than the urban area (18.2% versus 0.2%; p=0.001).

CONCLUSIONS

This study includes a large number of RSE cases and prophylaxis practices in southwestern Turkey. Most RSE cases had dog or cat contact. As most RSE cases were in urban areas; more focused efforts should be made for elimination and vaccination of feral dog and cat population in Turkey.

Phylogenetic analysis of the whole genome sequence of a dog lineage rabies virus detected from cattle in eastern China, 2019

Rabies is an important zoonosis worldwide, and this disease is caused by the rabies virus. Dogs and bat are the major hosts of rabies virus; however, many animals could infect with the rabies virus. By biting or scratching by an infected animal, rabies virus can be transmitted to cattle which is an important domestic animal in animal husbandry. Here, we report a case about a rabies virus (abbreviated JSTZ190314) found in cattle in eastern China in 2019. Our findings suggest that this rabies virus JSTZ190314 was a dog-origin rabies virus and belonged to the Asia clade. Furthermore, we found that this JSTZ190314-like rabies virus has been prevalent in China for more than 13 years and infected six species of animals. Our findings suggested that enhanced surveillance and research of rabies virus infection in bovine populations is needed.

Comparison of antibody titres between intradermal and intramuscular rabies vaccination using inactivated vaccine in cattle in Bhutan

In developing countries, the cost of vaccination limits the use of prophylactic rabies vaccination, especially in cattle. Intradermal vaccination delivers antigen directly to an area with higher number of antigen-presenting cells. Therefore, it could produce equivalent or higher antibody titres than conventional intramuscular vaccination even when a lower dose is given. This study aimed to compare the antibody response in cattle vaccinated intramuscularly with 1mL of inactivated rabies vaccine (Raksharab, Indian Immunologicals) against intradermally vaccinated cattle with 0.2mL of the same vaccine. The study was conducted in Haa province of Bhutan where rabies is not endemic. One hundred cattle from 27 farms were selected for the study. Virus neutralising antibody (VNA) response was measured using the fluorescent antibody virus neutralisation test on the day of vaccination (day 0) and 14, 30, 60 and 90 days later. Overall, 71% of intradermally vaccinated cattle and 89% of the intramuscularly vaccinated cattle produced an adequate response (≥0.5IU/mL). On days 14 and 30 post vaccination fewer cattle (P<0.02) in the intradermal group had adequate titres with 36% and 58%, respectively, having titres ≥0.5 IU/mL compared to the equivalent figures of 78% and 77% in the intramuscular group. The mean VNA titres were lower for the intradermal group than intramuscular group (p<0.001) with the mean difference being > 0.6 IU/mL. Although low dose intradermal vaccination did produce a detectable antibody response, it was inferior to intramuscular vaccination. Thus, although intradermal vaccination has the potential to reduce the cost of vaccination by reducing the dose required, this study showed that a single dose of 0.2 mL intradermally was inferior to an intramuscular dose of 1 mL. Further research evaluating dose and dose regimen is needed before intradermal vaccination using the Raksharab rabies vaccine can be recommended in cattle.

Ecology and epidemiology of rabies in humans, domestic animals and wildlife in Namibia, 2011-2017

Rabies is a fatal zoonotic disease that causes a heavy burden on societies. Namibia, a country in southern Africa, is aiming at controlling the disease in its main reservoir, the domestic dog. To facilitate the implementation comprehensive information on the ecology and epidemiology of the disease and surveillance is of utmost importance. The study presented assesses the baseline data for both human and animal rabies surveillance in Namibia in recent times and establishes correlations with ecological and socio-economic data in order to provide an up-to-date picture on the epidemiology of rabies in Namibia. For instance, it was important to identify the main drivers in the epidemiology, and whether the control strategy by mass vaccination of dogs is undermined by cycles of rabies in wildlife. Rabies in humans was reported mainly from the Northern Communal Areas (NCAs), with a total of 113 cases from 2011 to 2017, representing an incidence of between 1.0 and 2.4 annual human rabies deaths per 100,000 inhabitants. Kavango, the region with the highest human rabies incidence was also the region with the lowest animal rabies surveillance intensity. Generally, the vast majority (77%) of dog samples originated from communal farm land, followed by urban areas (17%), while only a small fraction (3%) was submitted from freehold farm areas. In contrast, kudu and eland submissions were almost exclusively from freehold farmland (76%) and urban areas (19%), whereas the submission of cattle samples was evenly distributed among freehold farms (46%) and communal farm land (46%). The likelihood of sample submission decreased exponentially with distance to one of the two laboratories. Overall, 67% (N = 1,907) of all samples submitted tested rabies-positive, with the highest positivity rate observed in kudus (89%) and jackals (87%). The transmission cycle of rabies in dogs appears restricted to the northern communal areas of Namibia, whilst rabies in wildlife species is predominately reported from farmland in central Namibia, mostly affecting kudu (Tragelaphus strepsiceros) and livestock with a likely reservoir in wildlife canids such as jackals or bat-eared foxes. The analysis confirms the presence of two independent transmission cycles in Namibia with little geographic overlap, thus allowing for a sustainable control of rabies in dogs in the NCAs.

Quantifying the burden of vampire bat rabies in Peruvian livestock

Background

Knowledge of infectious disease burden is necessary to appropriately allocate resources for prevention and control. In Latin America, rabies is among the most important zoonoses for human health and agriculture, but the burden of disease attributed to its main reservoir, the common vampire bat (Desmodus rotundus), remains uncertain.

Methodology/Principal findings

We used questionnaires to quantify under-reporting of livestock deaths across 40 agricultural communities with differing access to health resources and epidemiological histories of vampire bat rabies (VBR) in the regions of Apurimac, Ayacucho and Cusco in southern Peru. Farmers who believed VBR was absent from their communities were one third as likely to report livestock deaths from disease as those who believed VBR was present, and under-reporting increased with distance from reporting offices. Using generalized mixed-effect models that captured spatial autocorrelation in reporting, we project 4.6 (95% CI: 4.4–8.2) rabies cases per reported case and identify geographic areas with potentially greater VBR burden than indicated by official reports. Spatially-corrected models estimate 505–724 cattle deaths from VBR in our study area during 2014 (421–444 deaths/100,000 cattle), costing US$121,797–171,992. Cost benefit analysis favoured vaccinating all cattle over the current practice of partial vaccination or halting vaccination all together.

Conclusions

Our study represents the first estimate of the burden of VBR in Latin America to incorporate data on reporting rates. We confirm the long-suspected cost of VBR to small-scale farmers and show that vaccinating livestock is a cost-effective solution to mitigate the burden of VBR. More generally, results highlight that ignoring geographic variation in access to health resources can bias estimates of disease burden and risk.

The number of cases and monetary cost of a disease guides how resources for prevention and control are allocated. In Latin America, rabies transmitted by vampire bats is one of the most recognized zoonoses affecting humans and livestock, but its burden on lives and livelihoods has been difficult to calculate because the percentage of outbreaks that are not reported to surveillance systems is unknown. Here, using surveys to calculate farmers’ tendencies to report livestock deaths, we estimate that over 500 cattle died of rabies in southern Peru in 2014, a loss of approximately US$170,000 or over 700 months of local income. Our results also show that the perceived risk of rabies strongly affected reporting of cattle mortality and vaccination coverage, suggesting that campaigns to increase awareness could reduce the burden of rabies.

Continuous cell lines from the Muscovy duck as potential replacement for primary cells in the production of avian vaccines

Veterinary vaccines contribute to food security, interrupt zoonotic transmissions, and help to maintain overall health in livestock. Although vaccines are usually cost-effective, their adoption depends on a multitude of factors. Because poultry vaccines are usually given to birds with a short life span, very low production cost per dose is one important challenge. Other hurdles are to ensure a consistent and reliable supply of very large number of doses, and to have flexible production processes to accommodate a range of different pathogens and dosage requirements. Most poultry vaccines are currently being produced on primary avian cells derived from chicken or waterfowl embryos. This production system is associated with high costs, logistic complexities, rigid intervals between harvest and production, and supply limitations. We investigated whether the continuous cell lines Cairina retina and CR.pIX may provide a substrate independent of primary cell cultures or embryonated eggs. Viruses examined for replication in these cell lines are strains associated with, or contained in vaccines against egg drop syndrome, Marek's disease, Newcastle disease, avian influenza, infectious bursal disease and Derzsy's disease. Each of the tested viruses required the development of unique conditions for replication that are described here and can be used to generate material for in vivo efficacy studies and to accelerate transfer of the processes to larger production volumes.

Interplay between rabies virus and the mammalian immune system

Rabies is a disease caused following infection of the brain by the rabies virus (RABV). The principle mechanism of transmission is through a bite wound. The virus infects peripheral nerves and moves to the central nervous system (CNS). There appears to be little involvement of other organ systems and little detectable immune stimulation prior to infection of the CNS. This failure of the mammalian immune system to respond to rabies virus infection leads, in the overwhelming majority of cases, to death of the host. To some extent, this failure is likely due to the exclusive replication of RABV in neurons and the limited ability to generate, sufficiently rapidly, an anti-viral antibody response in situ. This is reflected in the ability of post-exposure vaccination, when given early after infection, to prevent disease. The lack of immune stimulation during RABV infection preceding neural invasion is the Achilles heel of the immune response. Whilst many viruses infect the brain, causing encephalitis and neuronal deficit, none are as consistently fatal to the host as RABV. This is in part due to prior replication of many viruses in peripheral, non-neural tissue by other viruses that allows timely activation of the immune response before the host is overwhelmed. Our current understanding of the correlates of protection for rabies suggests that it is the action of neutralising antibodies that prevent infection and control spread of RABV. Furthermore, it tells us that the induction of immunity can protect and understanding how and why this happens is critical to controlling infection. However, the paradigm of antibody development suggests that antigen presentation overwhelmingly occurs in lymphoid tissue (germinal and non-germinal centres) and these are external to the CNS. In addition, the blood-brain-barrier may provide a block to the delivery of immune effectors (antibodies/plasma B-cells) entering where they are needed. Alternatively, there may be insufficient antigen exposure after natural infection to mount an effective response or the virus actively suppresses immune function. To improve our ability to treat this fatal infection it is imperative to understand how immunity to RABV develops and functions so that parameters of protection are better defined.