Sources of rabies / transmission routes / emergency treatment / existence and history of prevention and control

According to data released by the World Health Organization (WHO), rabies is prevalent in 150 countries worldwide, mainly in Asia and Africa, resulting in 59,000 deaths each year According to data released by the National Bureau of Disease Control and Prevention, rabies ranks 10th in the national statistics of morbidity and mortality from legally reported infectious diseases in 2021.

Understanding the rabies virus

Rabies is known to be a fatal but preventable zoonotic disease. Rabies is caused by infection with the rabies virus, which is a bullet-shaped, enveloped virus particle (180 x 75 nm in size). According to Yan Jiaxin, a researcher at the Wuhan Institute of Biological Products, there are more than ten different rabies virus genotypes known, and the classical rabies virus (RABV-genotype 1) and its many variants are widely distributed around the world and cause rabies in humans and animals. Rabies in humans is essentially caused by this virus.

Rabies virus mainly invades the body through broken skin or mucous membranes, and the clinical manifestations are specific fear of wind, fear of water, pharyngeal muscle spasms, and paralysis. It is reported that the most common way for the rabies virus to enter the human body is through the bite or scratch of a diseased animal, and infection via incomplete skin. Non-bite exposure routes include inhalation of the aerosolized rabies virus, corneal/organ transplants, abrasions, open wounds, and mucous membranes contaminated with infectious material such as saliva or animal brain tissue containing rabies virus. "The success rate of mucosal contamination exposure to rabies is very low." Yan Jiaxin said. After being bitten by an animal known to have rabies, the probability of an untreated individual developing rabies varies depending on the site of the bite, from 50 to 80 percent for head bites, 15 to 40 percent for hand or arm bites, and 3 to 10 percent for leg bites.

It is important to note that the WHO has determined that ingesting raw meat or other tissue from an animal that has been infected with rabies is not a source of infection for human rabies.

Rabies virus is known to infect all mammals, but not birds, reptiles, amphibians, and all other lower animals. The reservoir hosts of the rabies virus are distributed only in two orders of mammals, Carnivora and Pteropods, and the virus can continue to spread in this species group, and neither the virus nor the animal will become extinct. Ninety-nine percent of human rabies originates in dogs, so dogs are the most important reservoir host animal for the rabies virus. Incidental hosts cannot sustain the persistence of the rabies virus, said Yan Jiaxin. Such animals include domestic animals such as horses, cattle, and pigs, as well as rodents, which do not usually transmit rabies.

Wang Chuanlin, deputy director of emergency surgery and deputy director of the trauma treatment center at Peking University People's Hospital, said that a person infected with the rabies virus will go through three periods: the incubation period, the prodromal period, and the typical period.

The incubation period is the period between the bite of a sick dog and the appearance of clinical symptoms. Rabies is asymptomatic during the incubation period. The incubation period is usually 0 to 3 months, as short as 1 week or as long as 1 year (very rare), and the longest incubation period found so far is 8 years. The closer the wound is to the central nerve, the faster the onset.

The virus in the prodromal phase travels along the nerve and retrogrades upward to the spinal cord. There are abundant nerve roots in the spinal cord where the virus will replicate in large numbers, causing spinal radiculitis. At this point, the patient will experience early symptoms such as headache, nausea, numbness, and pain in the area of the bite.

In the typical stage, the virus reaches the brain along the spinal cord and replicates profusely, breaking the blood-brain barrier. The virus then disperses along the peripheral nerves throughout the body, at which point typical clinical manifestations occur, such as fear of water, fear of wind, pharyngeal muscle spasms, and excessive salivation. Once it enters the typical stage, the patient will be in great pain. A foreign scholar has said that disease in the world can compare to the suffering of rabies.

Rabies can be eliminated

The main purpose of GARC's World Rabies Day is to raise awareness of rabies prevention and the progress made by mankind in the fight against this terrible disease, and to join in the global campaign to eliminate rabies.

This year's theme is intended to focus on "One Health" and to remind people of the goal of "Zero by 30" by 2030 --The elimination of dog-mediated rabies in humans is entirely possible.

In December 2015, WHO and the World Organization for Animal Health (OIE), in collaboration with the Food and Agriculture Organization of the United Nations (FAO) and the Global Alliance for Rabies Control, launched the Global Framework for Zero Human Rabies Deaths by 2030, a global goal to eliminate rabies by 2030. This initiative marks the first time that human and animal health sectors have come together to adopt a common strategy to conquer this terrible but still neglected disease. It is an important new milestone in the global process of rabies elimination.

The Global Strategic Plan to Eliminate Dog-Induced Human Rabies Deaths by 2030 is an ambitious document with achievable goals. It is aligned with the WHO Roadmap on Neglected Tropical Diseases (NTDs), which states that integrated interventions for NTDs will be prioritized and NTD planning will be mainstreamed into national health systems.

The Global Rabies Strategic Plan and the Roadmap are directly related, and the integrated approach advocated therein is of great importance, especially to rebuild and strengthen health systems and rabies control planning in collaboration with stakeholders, advocates, and people at the community, local, national, and global levels. Rabies can be eliminated through collaboration and resource integration, community mobilization, and a commitment to the ongoing universal vaccination of dogs.

Rabies has been known for ages

The earliest record of rabies in ancient Chinese texts is found in the Zuo Zhuan, which states, "In the seventeenth year of the eleventh month of the eleventh month (i.e., 556 B.C.) of the seventeenth year of the reign of Duke Xiang (Lu), the people of the state banished hydrophobic dogs." This indicates that mad dogs (i.e., rabies) existed in China 2500 years ago, and it was recognized at that time that mad dogs were extremely harmful to people, and measures were taken to expel them. According to the modern view, more than 95% of rabies in humans are caused by rabid dogs, and the expulsion of rabid dogs can significantly reduce the incidence of the disease in the population.

In 1708, an outbreak of rabies in domestic dogs of considerable size was first recorded in Italy. Many rabid dogs were also seen in England between 1734 and 1735, and in the 19th century, rabies was prevalent in almost every European country, causing great fear in the population. In Africa, rabies has been clearly documented since 1772, when it was introduced from England and gradually developed throughout Africa, more in North Africa and East Africa and less in West Africa.

A combination of historical data from various countries suggests that rabies probably originated in Asia or Europe in the Eastern Hemisphere. Rabies in the Western Hemisphere was most likely introduced in Europe in the 18th century. Rabies was not first detected in North America until 1753 in dogs in the Virginia colony, and human rabies was first detected in Boston in 1768. By 1785 rabies was found throughout the northern United States. In South America, canine rabies was not discovered in Peru until 1803, and rabies in Argentina dates back to 1806 when it was introduced by a dog carried by a British official.

A short history of prevention and control

Yan Jiaxin noted that the history of effective human prevention and control of rabies is only a little more than 100 years old, a history that includes the following six major events.

In 1885, French microbiologists such as Pasteur, who did not yet understand the nature of the rabies virus, worked out in practice a method for producing a rabies vaccine, laying the foundation for a fundamental solution to the prevention and control of rabies. The prevention of viral diseases by vaccines, except for the smallpox vaccine, the rabies vaccine was one of the first to be successfully applied.

In 1903, the Italian Necchi discovered rabies virus inclusion bodies, Necchi's bodies, within infected nerve cells, which could be used in early diagnostic studies of rabies (this method is now mostly replaced by the fluorescent antibody test or FAT).

In the 1940s scientists began to apply effective rabies vaccines to dogs in large numbers, which significantly reduced the incidence of human rabies and contributed to the creation of more rabies-free countries and regions.

In 1954, researchers added super immune antiserum (immunoglobulin) to the human rabies immunization program, further improving the survival rate of people severely bitten by rabid dogs.

In 1958, scientists successfully adapted the rabies virus to proliferate in cell culture. Subsequent cell culture vaccines produced using this technology have been refined in terms of safety and efficacy and have become popular in developed countries such as Europe and the United States, but at a higher cost.

In recent years, new oral recombinant vaccines produced using genetic engineering techniques (e.g., pox vaccine - rabies virus glycoprotein recombinant vaccine) have proven to be extremely effective and convenient in experimental animals and have been tried on a large scale in wild animals in Europe and the United States.

Yan Jiaxin said that since more than 95 percent of rabies in humans is dog-related, the successful experience of many countries that have eradicated rabies proves that by controlling rabies in dogs and other domestic pets, the incidence of rabies in humans can be greatly reduced.

Gao Fu, an academician of the Chinese Academy of Sciences, also mentioned that the elimination of rabies requires strengthening rabies surveillance in animals, including wild animals, improving the rate of laboratory diagnosis of reported cases, continuing to do a good job of analyzing rabies surveillance data and risk assessment; prioritizing rabies prevention and control in animals, preventing the spread of rabies in wild animals to the canine population and spillover, and the immunization rate of dogs in high-risk areas must reach more than 70%.

At the same time, Wang Chuanlin pointed out that civilized dog breeding and dog breeding according to the law should be promoted, the stray dog shelter system should be improved, the knowledge of rabies prevention and treatment should be continuously popularized, and public awareness of rabies should be enhanced. Only if the whole society pays enough attention can human rabies be eliminated as soon as possible to prevent tragedies from happening again.

Learn to deal with emergencies

The WHO has proposed the "ten-day observation method", which means that if the injured animal does not develop rabies within 10 days, the person is safe. Theoretically, a sick animal will not survive 10 days without treatment. However, China is a high-risk country for rabies, if the animal died on the 10th day, at this time, and then is treated according to rabies, there is a delay of 10 days.

Therefore, Wang Chuanlin introduced the emergency treatment "three steps".

To prevent wound infection, early treatment is the key. Rabies infection and tetanus infection have a certain incubation period, after being wounded by animals, even small wounds should not be taken lightly and carelessly. Rabies and tetanus are both serious diseases that are difficult to treat and have a high death rate once they strike. But at the same time, both are completely preventable, and the key to prevention is early treatment. For example, if you are bitten or scratched by a dog or cat, the first time cleaning and disinfecting the wound can effectively reduce the local germ load and reduce the risk of wound infection. At the same time, timely medical treatment, according to the wound situation and personal immunization history to do rabies post-exposure disposal and tetanus prophylaxis measures.

Wounds are divided into light and heavy, and treatment has principles. For the treatment of heavy wounds, especially active bleeding wounds, compression should be used to stop bleeding before rushing to the hospital; the principle of handling light wounds is to rinse, rinse, rinse again, disinfect or go directly to the hospital to find medical professionals for standardized disposal. If the wound is not large, you can first wash the wound at home with flowing water assisted by soapy water (or weak alkaline detergent) for 15 minutes. After rinsing, use a clean cloth or towel to absorb the residual fluid from the wound, cover the wound and seek medical attention as soon as possible.

To eliminate rabies, animal immunization comes first. After being injured by an animal with a high risk of spreading or contracting rabies, prompt medical attention and post-exposure prophylaxis are recommended, and post-exposure treatment is almost 100% effective.

Vaccines for safety

Wu Chihong, the deputy chief physician of the Department of Infectious Diseases at Peking University First Hospital, said the only way to prevent rabies is through vaccination. The human rabies vaccination is a remedial measure, the last line of defense against rabies. To eliminate canine-to-human rabies, dogs must not be diseased, and rabies vaccination for dogs is the most economical, effective, and long-lasting strategy.

Human rabies vaccines can be divided into two categories, post-bite prophylaxis, and no-bite prophylaxis. "Bites and scratches by animals (including seemingly healthy animals) must be vaccinated with post-bite prophylaxis. In addition, people who frequently come into contact with stray cats and dogs should have pre-exposure rabies vaccination." Wu Chihong explained.

"Rabies vaccination needs to be administered in stages, and common injection methods include the 'five shot method' and the '211' method." Wu Chibhong introduced the "five shot method", that is, one shot on day 0, day 3, day 7, day 14, and day 28 of exposure; the "211" method, that is, one shot on the left and right upper arms on day 0, one shot on day 7 and one shot on day 21 after exposure.

The rabies vaccine is an inactivated vaccine. The inactivated vaccines can be used at the same time or at any time interval with any other type of vaccine and will not affect each other's effect. If simultaneous vaccination is required, it is recommended to take different sites to avoid local adverse reactions when the source cannot be identified. If simultaneous vaccination is not possible, the rabies vaccine should be given priority because the death rate from rabies is almost 100%.

Must the rabies vaccine be administered within 24 hours of the injury? Rabies is a lethal disease and requires prompt and standardized post-exposure care after exposure. The earlier the rabies vaccination is given, the better, but it is still effective if given more than 24 hours after the injury. For those who have not had post-exposure treatment after a rabies exposure, even after several months, if the health status of the injured animal is unknown, it is recommended that rabies vaccination be administered according to procedures to avoid risk.

Rabies vaccination for pregnant and lactating women is also safe and will not adversely affect the fetus or infant.