This month, New York City saw its first resurgence of rabies in racoons since 2011 in several upper Manhattan parks. Due to the disease’s acute and fatal nature, the Department of Health has implemented an aggressive plan to combat the spread of rabies in the region. People living in these areas have been advised to keep safe distances from wild animals, to vaccinate their pets at home, and to immediately report and seek medical attention for any bites or scratches from animals. Additionally, the Department of Health has placed baited oral rabies recombinant vaccines throughout the affected areas to immunize potential vectors. These aggressive efforts have all been taken to help keep New York City rabies-free.
Stemming from Rhabas, meaning “to do violence”, rabies is a zoonotic viral infectious disease that attacks the central nervous system of mammals, typically resulting in delirium, hydrophobia, aggression or stupor, and eventual death. The virus responsible for causing rabies is known as rabies virus and is a part of the Rhabdoviridae family and Lyssavirus genus (Yousaf et al). It is most commonly transmitted through bites by an infected mammal or wounds in the skin, and canines make up its global reservoir. Rabies virus enters a break in the skin via saliva and replicates in the surrounding muscle cells. There, the rabies virus interacts at the neuromuscular junction and attaches to the nicotinic acetylcholine receptors on the peripheral nerve cells. The virus undergoes retrograde axonal transport along the microtubules of the nerve cell via dynein-dynactin/viral phosphoprotein interaction. This initiates a slow “crawl” of the virus towards the host’s central nervous system. Once the rabies virus reaches the cell body of the peripheral nerve cell, the bullet-shaped, glycoprotein-studded virus consisting of a negative-sense single-stranded RNA genome coding for five highly-conserved genes – nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G), and viral RNA polymerase (L) – undergoes “start-stop” transcription. Negri bodies are produced, the viral progenies are released by cell budding, and the new viruses are transported to the host’s salivary glands where they may be shed to cause a new infection (Yousaf et al).
An individual infected with rabies will first present with neuropathic pain, or a “tingling” sensation, at the site of their bite. Next, primary symptoms resembling other infectious diseases – headache, malaise, fever, nausea, and vomiting – appear. As the infection progresses, secondary symptoms arise. Secondary symptoms may be “furious” or “paralytic.” Patients experiencing furious rabies present with hydrophobia (“fear of water”), difficulty swallowing, agitation, anxiety, hallucinations, hypersalivation, bizarre behavior, biting, and jerky or violent contractions of the diaphragm. Patients experiencing paralytic rabies present with lack of hydrophobia, lack of hyperactivity, lack of seizures, and weakness or ascending paralysis. Eventually, an individual infected with rabies will slip into a coma and die. In fatal cases of rabies, death typically occurs approximately 18 days after the initial onset of symptoms. There have been some cases of spontaneous recovery in those affected by rabies which is why the disease is no longer considered 100% fatal; however, these cases are few and far between, and nearly half of these survivors were left with permanent neurological disorders.
Rabies is diagnosed through several routine tests such as RT-PCR or serology of saliva, tears, and cerebral spinal fluid. Other means of diagnosing rabies are Skin Punch Biopsies (where collections made from the nape of one’s neck are examined for rabies virus antigens) in humans that have been attacked or a post-mortem Direct Fluorescent Antibody technique performed on the nervous tissue of the animal that attacked. Once diagnosed, an unvaccinated individual will undergo a treatment consisting of Human Rabies Immunoglobulin (HRIG) at the site of the bite and the buttocks in combination with a series of Human Diploid Cell Rabies Vaccine (HDCV) or Purified Chick Embryo Cell Vaccine (PCECV). The immunoglobulin treatment derived from human plasma provides passive immunity to the affected individual until active antibodies spawn from the vaccination(s). This post-exposure prophylactic treatment requires early intervention to intercept the rabies virus before it reaches the central nervous system, otherwise it is essentially ineffective, and the infected individual is expected to die approximately 18 days after the onset of his or her symptoms. Because of the severity of rabies virus and urgency of treatment, preventing combating rabies has become a public health concern (Shors).
Initially, in the mid-twentieth century, rabies prevention strategies implemented in the United States caused a great decline in the number of domestic animal rabies cases; however, in the 1960s, it still remained a challenge to eliminate the virus in wild canines. To address this, the United States Department of Agriculture initiated the Wildlife Service (WS) Program, which provides efficacious federal assistance in control efforts of wildlife diseases, such as rabies, through the distribution of Raboral V-RG ® oral rabies vaccine (ORV) baits in affected areas. Since the implementation of this program, the majority of human rabies cases have been moved outside of the United States in countries where canine rabies is not controlled by vaccination and euthanasia (The majority of rabies cases in the United States today are derived from bats) (Burgos-Cáceres). That said, the World Health Organization (WHO) still estimates that nearly 55,000 people worldwide experience rabies-related deaths occur each year. To put that in perspective, that death toll equates to 150 human lives lost across the globe to rabies per day. This is tremendous. Contrary to popular belief, rabies is in no way a rare or insignificant disease in humans, especially in developing and transitioning countries. In fact, cases are grossly under-reported and its stats are still high. A largely believed reason for the lack of movement to control rabies is the lack of awareness of its true power (Coleman). This points to a larger ecological public health issue, and change must be made.
There are ample safe and effective pre-exposure prophylactic (PREP) methods, such as vaccines, for both animals and humans available for the disease’s prevention and control; however, the more significant challenge rabies poses is in the realm of wildlife management and public health in developing world areas with limited control efforts (Coleman). India and China are both incredibly high-risk environments for rabies, with unvaccinated, free-ranging canines throughout their countries. Recently, the incidence of rabies in these countries has increased (Zhang et al.). As seen in the United States, canine vaccination is an effective means to prevent human rabies, and if countries such as India and China would be willing to adopt such mass vaccination policies, it would be theoretically possible to eliminate deadly cases of rabies virus in people not only in these countries, but worldwide as well (Zhang et al.).
Today, the Global Alliance for Rabies Control (GARC) works to do just this – prevent rabies around the world. This organization and ones similar to it employ surveillance programs to identify what animals have rabies, where these animals reside, what humans have been infected by rabies, and which animals these infected humans have come in contact with. In considering all of these factors, the GARC and agencies alike are able to strategize the most effective and efficient ways to combat rabies worldwide (Shors).
Overall, rabies is a 100% controllable viral disease that has gone awry due to misinformation and negligence. It is time for a change. Future outbreak prevention and control of rabies calls for increased discussion between the medical, veterinary, and ecological approaches to the problem (Singh). With its lethal nature, treatment of humans from the medical realm alone is not enough to keep rabies at bay. Steps must be taken to prevent rabies from infecting humans in the first place. Enhancing surveillance to be more accurate as well as implementing a requirement for effective immunization programs for both wild and domestic animals would be a strong first step. Additionally, ongoing epidemiological data collection regarding the prevalence of rabies in both human and animal populations would be necessary. Lastly, public outreach and education is a must. With all of these approaches enforced, the world has the potential to eradicate rabies and bite back.
2019-4-26-1556245425