Happy World Rabies Day!
Although we’re a few days late, World Rabies Day is celebrated annually on September 28 since its inception in 2007. It was initiated to raise awareness about rabies, a fatal but completely preventable disease, in hopes to decrease its presence around the world.
Rabies is caused by the bullet-shaped rabies virus. It is considered a zoonotic disease, which means it can be transmitted from animals to humans. Animals like raccoons, dogs, foxes, skunks, cats, and bats are known to be reservoirs, or carriers, of the disease. The reason why rabies is so important that it gets its own World Rabies Day is because exposure to it spells certain doom. It causes irreparable neurologic damage that results in death.
But this is not a modern disease. It can be traced back to 500 B.C. when Democritus first described canine rabies1. Aristotle later wrote about the disease and how it caused irritability and madness in dogs and other animals that were bitten by these particularly abnormal dogs. Ever since then, we’ve seen the same cycle again and again. An agitated animal bites another animal or human, which then becomes agitated and irritable as well.
Fortunately, a person cannot get rabies from merely petting an infected animal. Instead, the virus has to enter the body through a cut or abrasion like an animal bite. Petting an infected kitten in a park won’t result in much, but if the kitten bites your hand, it could serious.
The trajectory of a rabies virus in a human body relies on a few factors:
1. Where the person was bitten (a bite on the foot is quite different than a bite on the face)
2. Severity of the wound (a deep bite that takes a chunk of your hand off versus a nibble that barely punctures the skin)
3. Amount of virus introduced into the body (this is not easy to detect like the first two factors)
These factors are interdependent, meaning they work together to create the firestorm that is rabies. Best case scenario is that someone gets bitten by a raccoon on their ankle, but the wound is not deep. Although the person should seek immediate medical attention, the chances of getting rabies after receiving the post-exposure vaccine should be pretty slim. However, if a rabid animal mauls someone’s face or neck, the chances of getting rabies considerably increases even with the post-exposure vaccine.
It’s all about how close the bite is to the brain because that’s where the rabies virus wants to go. It’s in the brain where it wreaks havoc. So the farther from the brain the bite is, the better. The less severe the wound is, the better. Smaller amounts of virus in an infected animal’s saliva means there might be less virus that enters the human body via the bite wound.
To be frank, rabies symptoms are not pleasant. Depending on three factors I mentioned earlier, the disease could take anywhere from a week to a few years to show any symptoms. This is because the virus must make its way to the brain, undetected by the immune system. Until then, one might experience the prodrome phase, which includes fever and itching near the site of the healed bite or wound2.
Once it reaches the brain, more serious symptoms become evident. One could develop what is called furious rabies, which commonly involves hydrophobia (violent muscle spasms and indescribable terror when trying to drink water – so the person ends up fearing water), hallucinations, fear, aggression, increased salivation, tear production, asphyxiation, sweating, coma, paralysis, and death. Furious rabies is the most common form of the disease, accounting for 80% of cases.
Another less common form of rabies is paralytic rabies, which involves ascending paralysis, loss of reflexes, apathy, depression, hallucinations, increased blood pressure, confusion, disorientation, coma, respiratory failure, and death.
These manifestations are extremely hard to watch as they reduce a human to animal-like behavior through loss of cognition and awareness. It is truly a sad disease and many underestimate it here in the United States simply because we hardly see it. But it is 100% fatal and should be taken as seriously as any other deadly disease.
But vaccines could help prevent this fate, which is why public health efforts are so focused on keeping animals and humans healthy to ensure a healthy environment. (This triad of animal-human-environment interaction is called One Health and will be a future topic!).
There are two types vaccines that pertain to rabies. Post-exposure prophylactic vaccines are administered after someone is bitten by a wild animal. This vaccine is given just in case the animal was infected so that the virus is eliminated before it can start to cause damage. Post-exposure vaccines are what people receive when they are rushed to the doctor to receive rabies treatment.
Then there are pre-exposure prophylactic vaccines, but these are usually given to veterinarians. They help protect a person against rabies before an exposure occurs. Since vets handle all kinds of creatures on a daily basis that may or may not be vaccinated, it makes sense for vets to be prepared in case they are ever bitten or scratched by an infected animal. Just be sure that your pets are up to date on their rabies vaccinations, too!
Unfortunately, human vaccines are not cheap. At all. Post-exposure prophylaxis vaccines are given in four doses over two weeks and cost about $3,000. In fact, overall public health costs associated with rabies prevention and control (i.e. pet vaccinations, human vaccinations for pre- and post- exposure, animal control programs, and laboratory testing) total about $300 million annually. But these public health measures save lives, so we continue to do what we can to ensure our communities are safe.
But vaccines aren’t the only prevention method we can use. We can make sure we stay away from animals acting erratically (i.e. nocturnal animals that are out during the day), vaccinate our companion animals regularly, abstain from feeding wildlife, call animal control to remove stray wildlife from our neighborhoods, and spay/neuter our companion pets to reduce the propagation of feral animals.
In the United States, we hardly see rabies cases. Actually, 90% of rabies-related deaths are due to wildlife transmission from raccoons, foxes, and skunks, among others3. Some still get rabies from contact with bats, which are known reservoirs of rabies. Even a bat scratch or graze is enough to send someone rushing to the doctor. Aside from those problematic winged mammals, prevention programs have been effective in reducing domestic rabies in our cats and dogs since the 1960s.
However, other countries are still battling rabies as an endemic, or well-established, disease in their communities. For example, Haiti is one of five remaining countries in the Western Hemisphere that still struggles with rabies among dogs. It also has the highest rate of human rabies deaths with about 2 deaths per week. Furthermore, Haiti has more than 1 million dogs of which only 45% are vaccinated against rabies. This presents a problem for controlling and preventing the spread of rabies among such a large population of animals amidst poor infrastructure and a severe shortage of healthcare access.
Cases like the one reported by the Centers for Disease Control and Prevention in 2015 describes the death of a villager from a dog bite. Upon reaching the village to investigate, CDC personnel learned that ten others were bitten by the same dog. Laboratory results confirmed the dog was positive for rabies and post-exposure vaccines were distributed despite shortages in the area.
In the summer of 2016, the CDC vaccinated 3,000 dogs in four days and plans to vaccinate 5,000 more dogs this year in Haiti. It may not be much compared to the 1 million total dogs in the country, but with other recent problems, it seems Haiti has a lot more on its plate that should also take precedence (See news about Hurricane Matthew and Cholera Outbreak).
Beyond Haiti, 95% of rabies-related deaths worldwide are reported solely in Asia and Africa, where rabies is still an endemic disease. In rural areas of these continents, rabies has seemingly slipped off the radar due to initiatives from other public health programs like HIV/AIDS, malaria, and Ebola. Additionally, dogs are not livestock, so they contain zero economical value or interest; therefore, they also slip off the radar. Like in Haiti, vaccinations are scarce in these areas of the world since they are not part of the Expanded Programme on Immunization system that monitors vaccine purchasing and administration.
But there’s hope amidst all this bleak news. Perhaps it’s the World Health Organization (WHO) being naively altruistic, blindingly optimistic, or ambitious to the point of exaggeration. But maybe they’re really onto something, and maybe they’re confident that everything will go as planned. Either way, the WHO wants to eradicate rabies by 2030. In a joint statement between the WHO, the World Organization for Animal Health (OIE), and the Food and Agriculture Organization of the United States (FAO), an agreement was reached on World Rabies Day on September 28, 2016. These organizations called on countries around the world to do three things:
“EDUCATE by raising awareness of rabies among at-risk populations
VACCINATE by implementing large-scale dog vaccination and ensuring prompt delivery of post- exposure treatment to humans in areas at risk of rabies
ELIMINATE by targeting a world free from dog-mediated human rabies deaths by 2030”
Maybe it’s the cynic in me that casts a shade of doubt over these goals. As a public health professional, I would love to assist with these initiatives and see them come to fruition. But in a world with re-emerging diseases and new diseases that we are still learning about (i.e. Ebola and Zika), we may or may not achieve the lofty goals we set for ourselves 14 years down the road. Who knows what new disease will come barreling through the population next year? Next week? Tomorrow? Who knows what other disease will take priority the way Zika did? (See Zika funding). We can certainly try to do our best to put an end to rabies because it is absolutely possible – absolutely necessary. We just need to ensure we stay on that long, winding, complicated, expensive road to eradicating rabies once and for all.
1Blanton, J.D., & Wallace, R.M. (2015). The ancient curse: Rabies. Microbiology Spectrum, 3(6). doi:10.1128/microbiolspec.IOL5-0018-2015.
2Warrell, M.J., & Warrell, D.A. (2015). Rabies: The clinical features, management and prevention of the classic zoonosis. Clinical Medicine, 15(1), 78-81.
3Centers for Disease Control and Prevention. (2016). Rabies in the U.S. Rabies. Retrieved From https://www.cdc.gov/rabies/locations/usa/index.html
Image Credit to Sarah EearlyWine.