Rabies is caused by the rabies virus. Humans can be infected through bites by rabid dogs, and other warm-blooded animals infected with this disease such as cats, wolves, and foxes can also transmit it. Its characteristic symptom is hydrophobia, meaning that when drinking water, patients experience spasms of the swallowing muscles and cannot swallow water; subsequently, patients feel extremely thirsty but dare not drink water, hence it is also called hydrophobia. Data shows that rabies has appeared in more than 100 countries worldwide, claiming tens of millions of lives.
Most human rabies cases result from bites (or scratches) by animals carrying the rabies virus. The incubation period can be as short as 10 days or as long as 2 years or more, generally 31 to 60 days; 15% occur after 3 months, depending on the distance of the bite from the central nervous system, the severity of the bite, or the dosage of the virus. Rabies has an extremely high fatality rate; almost all patients die once symptoms appear, with only a few survival reports worldwide.
However, if preventive injection is given timely after a rabid animal bite, the onset of the disease can almost always be avoided. Therefore, it is very important to widely spread knowledge about rabies so that bite victims can receive vaccination early. Rabies is found worldwide, and still occasionally occurs in China. Because this disease also exists in wild animals, complete eradication is very difficult, but good management of domestic dogs can greatly reduce morbidity. Rabies usually has a short prodromal period of about 1 to 4 days, presenting moderate fever, discomfort, loss of appetite, headache, nausea, and other symptoms; then it enters the neurological symptom phase, lasting about 2 to 20 days, with increased excitability, chest oppression, chest pain, and aerophobia, meaning that air blown onto the face can induce spasms of the throat muscles—a typical symptom helpful for diagnosis.
The wound area experiences pain or abnormal sensations, and some patients exhibit heightened reactivity to light, noise, and sensory stimuli, usually with increased muscle tone and facial muscle spasms. After damage to the sympathetic nervous system, symptoms include excessive sweating, salivation, manic behavior, anxiety, painful spasmodic muscle contractions, and muscle spasms in the throat during swallowing causing fear of drinking water, hence also called hydrophobia. Within 14 days after symptom onset, patients often develop secondary respiratory and heart failure after spasms, progressing to coma and death.
Rabies can be prevented by vaccine, but there is no specific effective treatment. More than 90% of patients die after onset, so prevention is crucial. Records of rabies in China date back to ancient times. The "Zuo Zhuan" mentioned driving away mad dogs to prevent rabies. The medical writings from the Han tomb of Ma Wang Dui in Changsha include the name "rabies." During the Jin dynasty, Ge Hong's "Emergency Prescriptions for Arm" recorded: "For all mad dog bites, symptoms appear in seven days; if after 37 days no symptoms appear, the patient recovers; it takes over 100 days to be completely safe."
The Sui dynasty's "Treatise on the Origins and Symptoms of Various Diseases" had detailed discussions on the incubation period, clinical symptoms, and treatments for rabies. Although early people had preliminary understanding of rabies, breakthroughs in prevention and treatment were achieved by modern scientists, especially French microbiologist Pasteur. In the 19th century, rabies claimed hundreds of French lives annually. Starting from 1880, Pasteur began researching how to combat rabies.
Pasteur discovered that the longer the pathogen is oxidized in air, the weaker its toxicity becomes. If the weakened pathogen is placed in a favorable growth environment, such as a person or animal body, it would proliferate again. However, the pathogen produced in this way has very weak toxicity, insufficient to cause disease, but stimulates the immune system to produce antibodies, achieving immunity. This was Pasteur's "artificial attenuation method" (later called artificial immunization).
After developing the rabies virus vaccine, Pasteur successfully tested it on dogs but hesitated to try it on humans. One morning in 1885, a worried middle-aged woman came to Pasteur's institute, begging him to save her child Joseph, who had been bitten by a rabid dog. That morning, Joseph was severely bitten by a mad dog outside his home, a critical condition that, without timely treatment, would likely result in death within 5 days.
Pasteur knew that vaccinating Joseph would have only two possible outcomes: save Joseph or accelerate his death. After careful consideration, he risked vaccinating Joseph. On the first day, he used a very small dose, gradually increasing it daily. A few days later, Joseph miraculously recovered, marking the birth of the rabies vaccine for humans.
Pasteur's artificial immunization method laid a strong foundation for modern immunology.