Information about rabies

Rabies causes tens of thousands of human deaths every year, mostly in Asia and Africa, and it also affects domestic and wild animals. Dogs are responsible for up to 99% of transmission cases to humans, highlighting the importance of controlling the disease within the canine population.

Early detection, preventive vaccination, and rapid response after exposure are critical to reducing mortality. Rabies also has a strong economic impact due to the costs of post-exposure treatments, animal control programs, losses in the livestock sector, and trade restrictions in endemic areas.

The causative agent is a virus belonging to the genus Lyssavirus, family Rhabdoviridae. It has a helical capsid structure wrapped in a lipid envelope containing viral glycoproteins essential for entry into host cells. Its genome consists of negative-sense single-stranded RNA.

This virus shows high neurotropism, meaning it has an affinity for nervous tissue. Once it enters the body through a wound, it travels through the peripheral nervous system until it reaches the brain, where it multiplies and triggers a lethal encephalitis.

There are several variants of the rabies virus adapted to different animal reservoirs. In Latin America, the main hosts are dogs, hematophagous bats (such as Desmodus rotundus), foxes, and raccoons. The circulation of the virus in wildlife represents a major challenge for eradication.

In countries where canine rabies has been eliminated, bats remain a source of transmission. Variants may present genetic and antigenic differences that impact epidemiological surveillance and vaccination strategies.

Rabies is mainly transmitted through the bite of an infected animal, as the virus is present in high concentrations in saliva during the last days before the animal's death. It can also be transmitted through scratches or when infected saliva comes into contact with mucous membranes or open wounds. Transmission via inhalation or organ transplantation is extremely rare but has been documented.

In animals, the disease spreads through close contact between individuals, particularly in areas with large populations of stray dogs or uncontrolled wildlife. Human interaction with domestic or wild animals in rural or peri-urban areas increases the risk of transmission.

The main reservoirs of the virus are dogs in urban and rural areas, and bats in wild or agricultural areas. Other species such as raccoons, skunks, and foxes can also act as reservoirs. Although technically there is no biological vector as in other diseases (i.e., an insect vector), wildlife plays an essential role in the persistence of the virus in the environment.

In the Americas, mass vaccination programs have drastically reduced transmission in dogs, but outbreaks associated with bats remain a challenge. Monitoring these reservoirs is key to implementing effective prevention strategies.

Human rabies has an incubation period that varies between 1 and 3 months, although it may extend depending on the site of viral entry and viral load. Initially, symptoms are nonspecific: fever, headache, general malaise, and tingling or itching at the wound site.

As the disease progresses, neurological symptoms appear, such as anxiety, confusion, hallucinations, hydrophobia (fear of water), aerophobia (fear of air), muscle spasms, and paralysis. At this stage, rabies is almost always fatal. There are two clinical forms: furious rabies (the most common) and paralytic rabies (less obvious but also lethal).

Signs in animals vary by species. In dogs and cats, early symptoms may include behavioral changes, loss of appetite, fever, and isolation. Later, they may develop aggressiveness, excessive salivation, difficulty swallowing, and movement disorders. Some develop progressive paralysis leading to death.

In livestock, rabies may manifest as muscle weakness, incoordination, abnormal vocalizations, and even aggressive behavior. In bats, signs often go unnoticed, making these animals silent reservoirs of the disease.

Clinical diagnosis of rabies in humans and animals is based on exposure history, neurological symptoms, and rapid progression to coma and death. However, definitive confirmation can only be made through laboratory tests. The most common test is direct immunofluorescence on post-mortem brain tissue, especially in animals.

Other methods include PCR (polymerase chain reaction) for viral RNA detection in saliva, skin biopsies, or cerebrospinal fluid. Serological tests can detect antibodies but are not useful in early stages.

Active and passive surveillance is essential to detect rabies outbreaks in animals and humans. Reporting systems make it possible to quickly identify risk areas, assess the effectiveness of vaccination campaigns, and coordinate public health responses.

In many countries, reference laboratories centralize diagnosis and maintain databases for trend analysis. Joint work among ministries of health, agriculture, and environment is key for comprehensive surveillance under the One Health approach.

Vaccination is the most effective tool to prevent rabies. In humans, it is administered both as post-exposure prophylaxis (PEP) and pre-exposure prophylaxis (PrEP), especially in high-risk groups such as veterinarians, field biologists, and laboratory staff. In animals, systematic vaccination of dogs and cats is essential to break the transmission chain. Mass vaccination campaigns in risk areas have proven highly successful in drastically reducing cases.

A critical part of rabies control is the ethical and effective management of stray animal populations. Sterilization programs, responsible adoption, and control of animal abandonment are part of a comprehensive approach. Community collaboration is also important for reporting animals with suspicious behavior and avoiding unnecessary contact with wildlife.

Educational campaigns targeting the general population are essential to raise awareness about the risks of rabies and the actions to take after exposure. It is vital that people know the importance of vaccinating their pets, how to act in the event of a bite, and when to seek medical attention. Schools, media, and social networks can be key allies in spreading these messages.

Rabies represents a considerable economic burden for both public health systems and livestock. In humans, costs are related to emergency medical care, administration of immunoglobulins and vaccines, and productivity losses due to premature death. In veterinary settings, it causes losses from animal deaths, reduced livestock production, and trade restrictions. Additionally, vaccination campaigns and control programs require significant investment, especially in endemic regions.

Despite the initial cost of prevention programs, investment in mass dog vaccination, canine population control, and community education has proven highly cost-effective in the long term. Countries that have eradicated canine rabies have drastically reduced human cases and associated medical expenses. Sustained implementation of coordinated strategies between human and animal health sectors is key to advancing toward rabies elimination.

There are multiple reliable sources for those seeking to deepen their knowledge about rabies, its prevention, and management. Organizations such as the World Health Organization (WHO), the World Organisation for Animal Health (WOAH), the Pan American Health Organization (PAHO), and the Centers for Disease Control and Prevention (CDC) offer technical resources, prevention guidelines, surveillance protocols, and control strategies. These are aimed at health professionals, veterinarians, policymakers, and the general public.

In addition, universities and research institutions such as Iowa State University and its Center for Food Security and Public Health (CFSPH) publish updated scientific studies and educational materials. These resources are available online through academic platforms such as PubMed and Google Scholar, facilitating global access to quality information.

In case of suspected rabies exposure or an outbreak, it is essential to immediately contact the public health or veterinary authorities of the respective country. In the SICA region, each country has a ministry or secretariat of health responsible for zoonotic disease management. These agencies can provide guidance on the steps to follow, the location of healthcare services, and the available vaccination schemes. Official websites often provide hotlines, contact emails, and reporting guides.