CynthiaATL
Member
Canine rabies control – a worldwide issue
CANINE RABIES CONTROL – A WORLDWIDE ISSUE
The Wylie Veterinary Centre
Upminster, Essex, UK
This article examines the subject from the perspective of implementation of program, and highlights problems and challenges at the local level stressing opportunities for the veterinary profession and welfare groups. Rabies is often considered in relation to human deaths, so one might question its inclusion within an animal welfare session.
The oath of veterinarians qualifying in the US includes the phrase: “… I solemnlyswear to use my scientific knowledge and skills for thebenefit of society through the protection of animal health,the relief of animal suffering, the conservation oflivestock resources, the promotion of public health, and the advancement of medical knowledge....â€
This underlines our role in ensuring community health as well as animal welfare, thus the commitment to the “one medicine†philosophy. Traditional strategies for rabies control have tended to rely on mass destruction of dogs, often using indiscriminate and inhumane methods. Evidence shows such methods are ineffective (eg, Flores, Indonesia) so alternative coordinated and multifactorial strategies are required. The benefits of the human–animal bond to human health and child development are well documented. Zoonoses and dog bites pose a risk. The challenge is to devise ways to enjoy the benefits of this relationship and yet reduce the risks. This concept is just as valid for those in rural communities in Asia as it is in Western households. The human perception of risk will influence attitudes to dogs and hence the nature of their interaction with them. This in turn affects animal welfare. Improving the welfare of dogs requires changing human attitudes. Effective rabies control will not only reduce the many unnecessary and tragic human deaths, but will help change these attitudes and subsequently improve animal welfare.
RABIES VIRUS VARIANTS WORLDWIDE
Rabies virus variants occur widely throughout the world and have a reservoir in a variety of wildlife and domestic species. In the US during 2006, there were 6940 reported rabies cases in animals, of which 92% were in wildlife. The major animal groups included raccoons (37.7%), bats (24.4%), skunks (21.5%), foxes (6.2%), cats (4.6%), cattle (1.2%), and dogs (1.1%).Of the three human cases, two were attributable to bat rabies virus variants and one to an exposure to a dog in the Philippines. No cases of rabies associated with the dog/coyote rabies virus variant were reported. The last reported case of this strain was March 2004, supporting
the contention that the canine rabies virus variant is no longer in circulation in the US. This success has been achieved by canine vaccination and population control. In 2007, a number of projects in Texas, Florida, and
Alabama using oral bait vaccination were instituted with the aim of eliminating the Texas gray fox rabies virus variant. Dramatic decreases in human rabies cases have been reported in recent years in South America following dog vaccination programs and improved post exposure therapy for humans. In Western Europe, the main reservoir is the fox. In the late 1990s and early 2000 rabies in foxes was eliminated from a number of countries conducting oral vaccination campaigns (Switzerland, 1999; France, 2000; Belgium and Luxemburg, 2001; and the Czech Republic, 2004). The baits included tetracycline which acted as a marker in bones and subsequent surveillance indicated that an uptake of 70% of the baits was required for rabies elimination. The UK had relied on a 6-month quarantine for dogs and cats to maintain its rabies-free status. This has been relaxed for animals traveling under the Pet Passport Scheme which requires the animal be permanently identified using a microchip, vaccinated for rabies, and subsequently blood tested to demonstrate
adequate seroconversion.
THE REAL PROBLEM – AFRICA AND ASIA
Despite the virus being present throughout the world, the massive burden of human deaths is in Asia and
Africa where the dog remains the key reservoir. Indeed 98% of human deaths worldwide follow exposure to a rabid dog. It has been estimated that the annual human death toll from rabies in Africa is 23,700 and 31,500 in Asia. These are more common in poor rural communities (83%) rather than urban ones (17%) and children are especially at risk.
RABIES IN HUMANS – WHO GUIDELINES
Following a bite, the virus travels along nerve trunks to the brain. The length of the incubation period is proportional to the distance traveled, those where the bite is close to the head and neck having a shorter incubation and poorer prognosis. Once the clinical symptoms develop, a prolonged and distressing death will almost invariably follow. Fortunately all these deaths are preventable if the WHO guidelines on Rabies Preand Post-exposure Treatment in Humans (2002) are followed. Recommendations to abandon the production of brain-tissue vaccines and use modern cell-culture biologicals have generally been implemented (in 2008, only Bangladesh, Myanmar and Pakistan within Asia still produced brain tissue vaccines). Further research (eg, monoclonal antibodies) will continue to improve vaccine efficacy and safety. The WHO recommendations outline correct post-exposure wound care and define grades of exposure into three categories, which determine the appropriate post-exposure therapy necessary:
Category I: No exposure; therefore, no treatment if the history is reliable
Category II: Minor scratches or abrasions vaccine only
Category III: Trans-dermal bites or contamination of mucous membranes with saliva rabies immunoglobulin (RIG) plus vaccination. Traditionally multiple-dose intramuscular regimes have been used. Now intradermal regimes are advocated as they are equally effective yet reduce the volume of vaccine required, reducing the cost by 60% to 80%.
IMPLEMENTATION – PROBLEMS AT THE LOCAL LEVEL
Approximately 55,000 human deaths occur annually despite the availability of the tools to prevent them. The challenges at the local level include:
Lack of infrastructure and effective surveillance
Lack of awareness among health professionals
Lack of awareness among population
Lack of availability of biological products
Logistics of maintaining cold chain
Cost
Cultural concerns
The WHO (World Health Organization) guidelines outline the pathway of events from a suspect bite person/animal becoming ill, through medical care, laboratory confirmation, and reporting through the Ministry of Health ultimately to WHO. In reality, many developing countries may lack adequately trained personnel or facilities, and there is often lack of inter-sectorial cooperation. Accurate laboratory confirmation and surveillance is a key to any program, and revised recommendations for sampling and storing specimens has been very useful in the field. Cost remains a major hurdle. In 2004, it was reported that 7,000,000 people underwent post-exposure therapy in China, 2,500,000 in India, 638,000 in Viet Nam, and 80,000 in Sri Lanka. It has been calculated that the postexposure vaccination costs (direct medical costs and indirect patient costs) equate to $39.55 in Africa and $49.3 in Asia. If one considers the full post-exposure program (PEP) of vaccine and RIG (including transport costs and loss of income) the unit cost rises to approx $100. This is equivalent to 50 days wages for the average African and 30 days wages for the average Asian. The cultural concerns are a reflection of cost. In the villages around Jodphur, India, PEP may only be provided to boys as they are valued more highly than girls.
In 2007, there were 3,300 human deaths from rabies reported in China. This is an increasing trend and the
geographic areas affected are becoming more widespread. In a review of human cases, most were diagnosed on clinical signs rather than laboratory confirmation; 88% had been exposed to rabid dogs and 68% received no wound treatment; 97% were not given appropriate vaccination at the correct time, and RIG was not given in 94% of the cases. It has been estimated that the human population of China is 1.36 billion and the dog population approximately 75 to 200 billion. Assuming an exposure rate of 5%, the cost of human post-exposure vaccination (not including RIG) is of the order of 21 times greater than that of compulsory dog vaccination. The problem of basing a strategy on PEP alone is that it is dealing with consequences rather than addressing the problem at source and is not financially sustainable.
ALTERNATIVE STRATEGY BASED ON DOG VACCINATION
Numerous studies indicate that mass vaccination of dogs is effective in reducing the incidence of human rabies, and this could be a more cost-effective strategy in the medium term. In a Tanzanian study, it has also
been shown that reappearance of the disease can follow a reduction in the level of vaccination. Accurate population studies are necessary prior to the implementation of programs since it is important to ascertain which dogs are accessible to parenteral vaccination and which might require oral vaccination. The different components of the free-roaming population are described in “Humane Dog Population ManagementGuidance†(ICAM Coalition, 2008). Engagement of the community might allow a greater proportion of dogs to be targeted by the parenteral route than first expected. Effective engagement requires a full understanding of local cultural and religious considerations. The human consumption of dog meat adds a further complication in some Asian countries. The trade is flourishing and yet is not discussed openly in international meetings. Irrespective of any moral arguments, this trade poses some special problems. It would appear dogs are not vaccinated against rabies as it is considered this might taint the meat. Random sampling of brains from dog meat restaurants in China revealed a significant number of positive samples for rabies virus. Large numbers of dogs are apparently
transported by road from Thailand to Viet Nam.
WILDLIFE AND ENDANGERED SPECIES
Studies in the Serengeti, Tanzania, have demonstrated the complex interaction between wildlife,
humans, and their domestic livestock. Dogs have been a reservoir for both rabies virus and canine distemper virus, which have been implicated in decreases in populations of African Wild Dogs to dangerously low levels. The implementation of mass dog vaccination programs has not only reduced the human death toll, but the African Wild Dog populations are now showing signs of recovery. The logistical challenges associated with the introduction of these programs illustrate the need for understanding and engaging with the local community.
POLITICAL CHALLENGE
We have all the tools at our disposal to practically eliminate rabies but lack the political will. At the local
level, budgets are usually administered by human health ministries rather than veterinary ministries. A change in emphasis from PEP to dog vaccination requires greater inter-sectorial collaboration. There are those in the human health field that are skeptical of a shift to a reliance on dog vaccination—the fact that vaccine failures will occur is a problem in promoting such a change. At the international level, it is easier to attract funds for diseases that have the biggest impact. These are assessed in terms of “disease adjusted life years (DALYs).†Traditionally, rabies has been in the “second division†in comparison to diseases such as malaria, AIDS, and TB. Recent data has indicated that the incidence of rabies is probably significantly higher than reports had suggested, such that it is now being considered as a âœre-emerging†disease.
CANINE RABIES CONTROL – A WORLDWIDE ISSUE
The Wylie Veterinary Centre
Upminster, Essex, UK
This article examines the subject from the perspective of implementation of program, and highlights problems and challenges at the local level stressing opportunities for the veterinary profession and welfare groups. Rabies is often considered in relation to human deaths, so one might question its inclusion within an animal welfare session.
The oath of veterinarians qualifying in the US includes the phrase: “… I solemnlyswear to use my scientific knowledge and skills for thebenefit of society through the protection of animal health,the relief of animal suffering, the conservation oflivestock resources, the promotion of public health, and the advancement of medical knowledge....â€
This underlines our role in ensuring community health as well as animal welfare, thus the commitment to the “one medicine†philosophy. Traditional strategies for rabies control have tended to rely on mass destruction of dogs, often using indiscriminate and inhumane methods. Evidence shows such methods are ineffective (eg, Flores, Indonesia) so alternative coordinated and multifactorial strategies are required. The benefits of the human–animal bond to human health and child development are well documented. Zoonoses and dog bites pose a risk. The challenge is to devise ways to enjoy the benefits of this relationship and yet reduce the risks. This concept is just as valid for those in rural communities in Asia as it is in Western households. The human perception of risk will influence attitudes to dogs and hence the nature of their interaction with them. This in turn affects animal welfare. Improving the welfare of dogs requires changing human attitudes. Effective rabies control will not only reduce the many unnecessary and tragic human deaths, but will help change these attitudes and subsequently improve animal welfare.
RABIES VIRUS VARIANTS WORLDWIDE
Rabies virus variants occur widely throughout the world and have a reservoir in a variety of wildlife and domestic species. In the US during 2006, there were 6940 reported rabies cases in animals, of which 92% were in wildlife. The major animal groups included raccoons (37.7%), bats (24.4%), skunks (21.5%), foxes (6.2%), cats (4.6%), cattle (1.2%), and dogs (1.1%).Of the three human cases, two were attributable to bat rabies virus variants and one to an exposure to a dog in the Philippines. No cases of rabies associated with the dog/coyote rabies virus variant were reported. The last reported case of this strain was March 2004, supporting
the contention that the canine rabies virus variant is no longer in circulation in the US. This success has been achieved by canine vaccination and population control. In 2007, a number of projects in Texas, Florida, and
Alabama using oral bait vaccination were instituted with the aim of eliminating the Texas gray fox rabies virus variant. Dramatic decreases in human rabies cases have been reported in recent years in South America following dog vaccination programs and improved post exposure therapy for humans. In Western Europe, the main reservoir is the fox. In the late 1990s and early 2000 rabies in foxes was eliminated from a number of countries conducting oral vaccination campaigns (Switzerland, 1999; France, 2000; Belgium and Luxemburg, 2001; and the Czech Republic, 2004). The baits included tetracycline which acted as a marker in bones and subsequent surveillance indicated that an uptake of 70% of the baits was required for rabies elimination. The UK had relied on a 6-month quarantine for dogs and cats to maintain its rabies-free status. This has been relaxed for animals traveling under the Pet Passport Scheme which requires the animal be permanently identified using a microchip, vaccinated for rabies, and subsequently blood tested to demonstrate
adequate seroconversion.
THE REAL PROBLEM – AFRICA AND ASIA
Despite the virus being present throughout the world, the massive burden of human deaths is in Asia and
Africa where the dog remains the key reservoir. Indeed 98% of human deaths worldwide follow exposure to a rabid dog. It has been estimated that the annual human death toll from rabies in Africa is 23,700 and 31,500 in Asia. These are more common in poor rural communities (83%) rather than urban ones (17%) and children are especially at risk.
RABIES IN HUMANS – WHO GUIDELINES
Following a bite, the virus travels along nerve trunks to the brain. The length of the incubation period is proportional to the distance traveled, those where the bite is close to the head and neck having a shorter incubation and poorer prognosis. Once the clinical symptoms develop, a prolonged and distressing death will almost invariably follow. Fortunately all these deaths are preventable if the WHO guidelines on Rabies Preand Post-exposure Treatment in Humans (2002) are followed. Recommendations to abandon the production of brain-tissue vaccines and use modern cell-culture biologicals have generally been implemented (in 2008, only Bangladesh, Myanmar and Pakistan within Asia still produced brain tissue vaccines). Further research (eg, monoclonal antibodies) will continue to improve vaccine efficacy and safety. The WHO recommendations outline correct post-exposure wound care and define grades of exposure into three categories, which determine the appropriate post-exposure therapy necessary:
Category I: No exposure; therefore, no treatment if the history is reliable
Category II: Minor scratches or abrasions vaccine only
Category III: Trans-dermal bites or contamination of mucous membranes with saliva rabies immunoglobulin (RIG) plus vaccination. Traditionally multiple-dose intramuscular regimes have been used. Now intradermal regimes are advocated as they are equally effective yet reduce the volume of vaccine required, reducing the cost by 60% to 80%.
IMPLEMENTATION – PROBLEMS AT THE LOCAL LEVEL
Approximately 55,000 human deaths occur annually despite the availability of the tools to prevent them. The challenges at the local level include:
Lack of infrastructure and effective surveillance
Lack of awareness among health professionals
Lack of awareness among population
Lack of availability of biological products
Logistics of maintaining cold chain
Cost
Cultural concerns
The WHO (World Health Organization) guidelines outline the pathway of events from a suspect bite person/animal becoming ill, through medical care, laboratory confirmation, and reporting through the Ministry of Health ultimately to WHO. In reality, many developing countries may lack adequately trained personnel or facilities, and there is often lack of inter-sectorial cooperation. Accurate laboratory confirmation and surveillance is a key to any program, and revised recommendations for sampling and storing specimens has been very useful in the field. Cost remains a major hurdle. In 2004, it was reported that 7,000,000 people underwent post-exposure therapy in China, 2,500,000 in India, 638,000 in Viet Nam, and 80,000 in Sri Lanka. It has been calculated that the postexposure vaccination costs (direct medical costs and indirect patient costs) equate to $39.55 in Africa and $49.3 in Asia. If one considers the full post-exposure program (PEP) of vaccine and RIG (including transport costs and loss of income) the unit cost rises to approx $100. This is equivalent to 50 days wages for the average African and 30 days wages for the average Asian. The cultural concerns are a reflection of cost. In the villages around Jodphur, India, PEP may only be provided to boys as they are valued more highly than girls.
In 2007, there were 3,300 human deaths from rabies reported in China. This is an increasing trend and the
geographic areas affected are becoming more widespread. In a review of human cases, most were diagnosed on clinical signs rather than laboratory confirmation; 88% had been exposed to rabid dogs and 68% received no wound treatment; 97% were not given appropriate vaccination at the correct time, and RIG was not given in 94% of the cases. It has been estimated that the human population of China is 1.36 billion and the dog population approximately 75 to 200 billion. Assuming an exposure rate of 5%, the cost of human post-exposure vaccination (not including RIG) is of the order of 21 times greater than that of compulsory dog vaccination. The problem of basing a strategy on PEP alone is that it is dealing with consequences rather than addressing the problem at source and is not financially sustainable.
ALTERNATIVE STRATEGY BASED ON DOG VACCINATION
Numerous studies indicate that mass vaccination of dogs is effective in reducing the incidence of human rabies, and this could be a more cost-effective strategy in the medium term. In a Tanzanian study, it has also
been shown that reappearance of the disease can follow a reduction in the level of vaccination. Accurate population studies are necessary prior to the implementation of programs since it is important to ascertain which dogs are accessible to parenteral vaccination and which might require oral vaccination. The different components of the free-roaming population are described in “Humane Dog Population ManagementGuidance†(ICAM Coalition, 2008). Engagement of the community might allow a greater proportion of dogs to be targeted by the parenteral route than first expected. Effective engagement requires a full understanding of local cultural and religious considerations. The human consumption of dog meat adds a further complication in some Asian countries. The trade is flourishing and yet is not discussed openly in international meetings. Irrespective of any moral arguments, this trade poses some special problems. It would appear dogs are not vaccinated against rabies as it is considered this might taint the meat. Random sampling of brains from dog meat restaurants in China revealed a significant number of positive samples for rabies virus. Large numbers of dogs are apparently
transported by road from Thailand to Viet Nam.
WILDLIFE AND ENDANGERED SPECIES
Studies in the Serengeti, Tanzania, have demonstrated the complex interaction between wildlife,
humans, and their domestic livestock. Dogs have been a reservoir for both rabies virus and canine distemper virus, which have been implicated in decreases in populations of African Wild Dogs to dangerously low levels. The implementation of mass dog vaccination programs has not only reduced the human death toll, but the African Wild Dog populations are now showing signs of recovery. The logistical challenges associated with the introduction of these programs illustrate the need for understanding and engaging with the local community.
POLITICAL CHALLENGE
We have all the tools at our disposal to practically eliminate rabies but lack the political will. At the local
level, budgets are usually administered by human health ministries rather than veterinary ministries. A change in emphasis from PEP to dog vaccination requires greater inter-sectorial collaboration. There are those in the human health field that are skeptical of a shift to a reliance on dog vaccination—the fact that vaccine failures will occur is a problem in promoting such a change. At the international level, it is easier to attract funds for diseases that have the biggest impact. These are assessed in terms of “disease adjusted life years (DALYs).†Traditionally, rabies has been in the “second division†in comparison to diseases such as malaria, AIDS, and TB. Recent data has indicated that the incidence of rabies is probably significantly higher than reports had suggested, such that it is now being considered as a âœre-emerging†disease.