Stray Dogs and Rabies: What you should know

Image source: www.occupyforanimals.net

The National Animal Interest Alliance published the online article “The Global Stray Dog Population Crisis” by Pattie Strand in 2011. In this publication they emphasized the “epidemic” of stray dogs globally and quoted the World Health Organization estimates of more than 200 million stray dogs worldwide and that 55,000 people die from rabies, while another 15 million receive post exposure treatment to avert developing the disease after exposure. WHO data indicates that 99% of rabies cases occur in Asia and Africa, and 99% of the fatalities are caused by dogs.

“Rabies is a zoonotic disease, caused by the rabies virus. The rabies virus, a member of the Lyssavirus genus of the Rhabdoviridae family, survives in a diverse variety of animal species, including bats, monkeys, raccoons, foxes, skunks, wolves, coyotes, dogs, mongoose, weasels, cats, cattle, domestic farm animals, groundhogs, bears, and wild carnivores. However, dogs are the principal host in Asia, parts of America, and large parts of Africa. Mandatory vaccination of animals is less effective in rural areas, especially in developing countries where pets may be community property and their destruction unacceptable.” (Information source: click here).

The clinical signs of rabies in animals as published by the United States Centers Disease Control (CDC): Rabies virus causes an acute encephalitis in all warm-blooded hosts and the outcome is almost always fatal. The first symptoms of rabies may be nonspecific and include lethargy, fever, vomiting, and anorexia. Signs progress within days to cerebral dysfunction, cranial nerve dysfunction, ataxia, weakness, paralysis, seizures, difficulty breathing, difficulty swallowing, excessive salivation, abnormal behavior, aggression, and/or self-mutilation. Rabies has the highest case fatality rate of most infectious disease in humans.

In African countries, with very sparse documented research data, the estimated numbers of stray dogs are seen to continue to increase with increased risk of exposure to such dogs infected with rabies. A 1988 pilot study conducted jointly by S.I. Oboegbulem and I.E Nwakonobi, in the Department of Community Medicine, University of Glasgow, Glasgow, United Kingdom, and the Department of Veterinary Pathology and Microbiology, University of Nigeria, Nsukka, Nigeria, respectively, focused on population density and ecology of dogs in Nigeria. One of the observations of this study was that “The epidemiological and public health implications of large urban dog populations, partial restriction in urban areas and free range in the rural areas are apparent. These factors promote straying, encourage the gathering of dogs in packs, and facilitate easy contact between stray dogs and wildlife. Given the very low vaccination level observed, there is increased probability of transmission of diseases (especially rabies) from stray to owned dogs. Certainly, this maintains the cycle of endemic canine rabies. In addition, there are the problems of environmental pollution, social nuisance of dog bites, and the heightened human exposure risk to rabies.”

Another study of the epidemiology of rabies in Northern Nigeria was published in 1987 by C.D. Ezeokoli and J.U. Umoh, Faculty of Veterinary Medicine, Ahmadu Bello, University of Zaria, Nigeria. This study identified that “there seems to be a cyclic pattern of distribution of the outbreaks. Most dogs involved in bites had identifiable owners (74.5%), were older than one year (70.0%), and were not vaccinated (75.5%). Male children (under 10 years) were the high risk group for dog bites. Rabies cases seemed to cluster around April and September, corresponding to breeding seasons for dogs in Zaria.”

Interestingly, a more recent another study by Hambolu et al on”Dog Ecology and Population Studies in Lagos State, Nigeria published in the Global Journal of Health Science; Vol. 6, No. 2; 2014 by the Canadian Center of Science and Education had interesting findings: “A total of 1,427 dogs counted from the street counts while a total of 1,447 dogs (2.8 dogs/compound) were counted from the compound count. The dogs comprised of 583 males and 864 females, out of which 64.10% are confined. The dog vaccination coverage in the dog population surveyed was 64.10% and administered majorly (91.30%) by veterinarians. Security (60%) and pets (26%) were the major reasons for keeping dogs. Majority (88.80%) of the respondents were aware of rabies and its mode of transmission, but still believed in the use of concoctions (40.40%), herbs (19.90%) and consumption of the organ of the offending dog (11.50%) for the treatment of rabies. The findings of this study showed a male: female ratio of dog to be 1:1.5 and a dog: human ratio of 1:5.6. There was also a responsible dog ownership as majority of the respondents do confine, vaccinate and provide food for their dogs.” However that study noted that “vaccination coverage of the total dog population was however below the 70-80% target recommended by the World Health Organization to achieve herd immunity.”

Another study Otolorin et al. published in the Journal of Vaccines (Vaccin 2015, 6:1) conducted a review on human deaths associated with rabies in Nigeria. The study noted that detection of rabies antigen in the brain tissue of supposedly healthy dogs killed for human consumption in some states in Nigeria gives an indication of the endemic nature of the disease and the public health risk it poses. The results of the study reported of 78 deaths due to rabies across from 10 States in Nigeria, although not all cases were confirmed in laboratories. While it appeared from the study results that the reported number of cases was lower than expected, the authors attributed it to “poor reporting of cases, cultural beliefs, misdiagnosis of the disease and poor knowledge on the mode of transmission and prevention of the disease. The authors of the publication also noted there are increasing numbers of reported cases of dog bites in humans in both rural and urban areas in Nigeria and that other published researches in Nigeria have reported deaths in humans due to rabies infection.”

An online publication reported that in Sierra Leone it was estimated that the population of stray dogs have increased to half a million.The same online publication noted possible causes of the increase in stray dogs: With the Ebola outbreak, “”Many stray dogs were pets of Ebola victims and abandoned, as neighbors feared contracting the disease from the dog. Dogs living freely on the streets are at the risk of contracting rabies and passing it on by attacking, triggering fears that an entirely new health threat is growing in Sierra Leone.”

As suggested by Otolorin et al (Vaccin 2015, 6:1), it is important that the African governments consider rabies control as high priority and forge a sustainable collaborative effort between Veterinarians and human health care professionals on national rabies control program will help in the control of rabies.

What do we know about the prevalence and mortality report on human rabies?

• Human rabies is present in 150 countries and territories and on all continents, except for Antarctica.

• Rabies is 100% preventable by vaccination, yet continues to kill.

• Rabies is 100% fatal and 100% preventable

Almost all human deaths caused by rabies occur in Asia and Africa. There are an estimated 55,000 human deaths annually from rabies worldwide. Information source.

About Rabies

The following information is from the WHO Fact Sheet (Updated March 2016):

Key facts

• Rabies is a vaccine-preventable viral disease which occurs in more than 150 countries and territories.

• Dogs are the source of the vast majority of human rabies deaths, contributing up to 99% of all rabies transmissions to humans.

• Rabies elimination is feasible by vaccinating dogs.

• Infection causes tens of thousands of deaths every year, mostly in Asia and Africa.

• 40% of people who are bitten by suspect rabid animals are children under 15 years of age.

• Immediate wound cleansing with soap and water after contact with a suspect rabid animal can be life-saving.

• Every year, more than 15 million people worldwide receive a post-bite vaccination. This is estimated to prevent hundreds of thousands of rabies deaths annually.

Rabies is an infectious viral disease that is almost always fatal following the onset of clinical signs. In up to 99% of human cases, the rabies virus is transmitted by domestic dogs. Rabies affects domestic and wild animals, and is spread to people through bites or scratches, usually via saliva.

Rabies is present on all continents with the exception of Antarctica, but more than 95% of human deaths occur in Asia and Africa.

Rabies is a neglected disease of poor and vulnerable populations whose deaths are rarely reported and where human vaccines and immunoglobulin are not readily available or accessible. It occurs mainly in remote rural communities where children between the age of 5–14 years are frequent victims.

The average cost of rabies post-exposure prophylaxis (PEP) can be the cost of catastrophic expenses for poor populations, since a course of PEP can cost US$ 40 in Africa and US$ 49 in Asia, where the average daily income is about US$ 1–2 per person.

Prevention:

Eliminating rabies in dogs

Rabies is a vaccine-preventable disease. Vaccinating dogs is the most cost-effective strategy for preventing rabies in people. Dog vaccination will drive down not only the deaths attributable to rabies but also the need for PEP as a part of dog bite patient care.

Preventive immunization in people

The same safe and effective vaccines can be used for pre-exposure immunization. This is recommended for travellers spending a lot of time outdoors, especially in rural areas, involved in activities such as bicycling, camping, or hiking as well as for long-term travellers and expatriates living in areas with a significant risk of exposure to dog bites.

Pre-exposure immunization is also recommended for people in certain high-risk occupations such as laboratory workers dealing with live rabies virus and other rabies-related viruses (lyssaviruses), and people involved in any activities that might bring them professionally or otherwise into direct contact with bats, carnivores, and other mammals in rabies-affected areas. As children are considered at higher risk because they tend to play with animals, may receive more severe bites, or may not report bites, their immunization could be considered if living in or visiting high-risk areas.

Symptoms

The incubation period for rabies is typically 1–3 months, but may vary from <1 week to >1 year, dependent upon factors such as location of rabies entry and rabies viral load. The initial symptoms of rabies are fever and often pain or an unusual or unexplained tingling, pricking or burning sensation (paraesthesia) at the wound site. As the virus spreads through the central nervous system, progressive, fatal inflammation of the brain and spinal cord develops.

Two forms of the disease can follow. People with furious rabies exhibit signs of hyperactivity, excited behaviour, hydrophobia (fear of water) and sometimes aerophobia (fear of flying). After a few days, death occurs by cardiorespiratory arrest.

Paralytic rabies accounts for about 30% of the total number of human cases. This form of rabies runs a less dramatic and usually longer course than the furious form. The muscles gradually become paralyzed, starting at the site of the bite or scratch. A coma slowly develops, and eventually death occurs. The paralytic form of rabies is often misdiagnosed, contributing to the under-reporting of the disease.

Diagnosis

No tests are available to diagnose rabies infection in humans before the onset of clinical disease, and unless the rabies-specific signs of hydrophobia or aerophobia are present, the clinical diagnosis may be difficult. Human rabies can be confirmedintra-vitam and post mortem by various diagnostic techniques aimed at detecting whole virus, viral antigens or nucleic acids in infected tissues (brain, skin, urine or saliva).

Transmission

People are usually infected following a deep bite or scratch by an infected animal. Dogs are the main host and transmitter of rabies. They are the cause of human rabies deaths in Asia and Africa in more than 95% of all cases.

Bats are the source of most human rabies deaths in the Americas. Bat rabies has also recently emerged as a public health threat in Australia and western Europe. Human deaths following exposure to foxes, raccoons, skunks, jackals, mongooses and other wild carnivore host species are very rare.

Transmission can also occur when infectious material – usually saliva – comes into direct contact with human mucosa or fresh skin wounds. Human-to-human transmission by bite is theoretically possible but has never been confirmed.

Rarely, rabies may be contracted by inhalation of virus-containing aerosol or via transplantation of an infected organ. Ingestion of raw meat or other tissues from animals infected with rabies is not a confirmed source of human infection.

Post-exposure prophylaxis (PEP)

Post-exposure prophylaxis (PEP) means the treatment of a bite victim that is started immediately after exposure to rabies in order to prevent rabies from entering the central nervous system which would result in imminent death. This consists of:

• local treatment of the wound, initiated as soon as possible after exposure;

• a course of potent and effective rabies vaccine that meets WHO standards; and

• the administration of rabies immunoglobulin (RIG), if indicated.

Effective treatment soon after exposure to rabies can prevent the onset of symptoms and death.

Local treatment of the wound

This involves first-aid of the wound that includes immediate and thorough flushing and washing of the wound for a minimum of 15 minutes with soap and water, detergent, povidone iodine or other substances that kill the rabies virus.

Recommended PEP

Depending on the severity of the contact administering with the suspected rabid animal, administration of PEP is recommended as follows (see table):

Table: Categories of contact and recommended post-exposure prophylaxis (PEP)

Categories of contact with suspect rabid animal

Post-exposure prophylaxis measures

Category I – touching or feeding animals, licks on intact skin

None

Category II – nibbling of uncovered skin, minor scratches or abrasions without bleeding

Immediate vaccination and local treatment of the wound

Category III – single or multiple transdermal bites or scratches, licks on broken skin; contamination of mucous membrane with saliva from licks, contacts with bats.

Immediate vaccination and administration of rabies immunoglobulin; local treatment of the wound

All category II and III exposures assessed as carrying a risk of developing rabies require PEP. This risk is increased if:

• the biting mammal is a known rabies reservoir or vector species;

• the animal looks sick or displays an abnormal behaviour;

• a wound or mucous membrane was contaminated by the animal’s saliva;

• the bite was unprovoked; and

• the animal has not been vaccinated.

In developing countries, the vaccination status of the suspected animal alone should not be considered when deciding whether to initiate prophylaxis or not.

WHO continues to promote human rabies prevention through the elimination of rabies in dogs as well as a wider use of the intradermal route for PEP which reduces volume and thereby the cost of cell-cultured vaccine by 60% to 80%.

WHO response

Rabies, a zoonotic disease, requires close co-ordination between animal and human health sectors at the national, regional and continental levels.

In December 2015, a global framework to reach zero human rabies deaths by 2030 was launched by WHO and the World Organisation for Animal Health (OIE), in collaboration with the Food and Agriculture Organization of United Nations (FAO) and the Global Alliance for Rabies Control. This initiative marks the first time that the human and animal health sectors have come together to adopt a common strategy against this devastating but massively neglected disease.

Great strides have been made in the Philippines, South Africa and Tanzania where proof of concept projects as part of a Bill & Melinda Gates Foundation project led by WHO recently showed that a decrease in human rabies is possible through a combination of interventions involving dog vaccination, improved access to PEP, and increased surveillance and public awareness raising. The key towards sustaining and expanding the rabies programmes to new territories and countries has been to start small, demonstrate success and cost-effectiveness, and ensure community engagement.

Stockpiles of dog and human rabies vaccine have had a catalytic effect on rabies elimination efforts. WHO is working to assemble forecasts on the supply of human and dog vaccines and the need for rabies immunoglobulin, to understand the global manufacturing capacity and to explore bulk purchasing options for countries through WHO/UNICEF (human vaccine and RIG) and OIE/WHO (animal vaccine) mechanisms.

The use of stimulus packages consisting of technical and material support to kick-start rabies prevention programs for endemic countries and regions has proven successful. By enabling the implementation of proven control strategies, these create sustainable rabies elimination programs and could ideally be expanded to neighbouring regions and countries.

Rabies transmitted by dogs has been eliminated in many Latin American countries, including Chile, Costa Rica, Panama, Uruguay, most of Argentina, the states of São Paulo and Rio de Janeiro in Brazil, and large parts of Mexico and Peru.

Many countries in the WHO South-East Asia Region have embarked on elimination campaigns in line with the target of regional elimination by 2020. Bangladesh launched an elimination program in 2010 and, through the management of dog bites, mass dog vaccination and increased availability of vaccines free of charge, human rabies deaths decreased by 50% during 2010–2013.