Zoonotic diseases, also identified as zoonoses, are maladies spread from animals to humans. Throughout most of human history, they have posed a persistent danger, causing massive outbreaks and affecting global health. Reflecting on the lessons learned from the COVID-19 pandemic, it is clear that comprehension and managing zoonotic diseases is critical for both human and animal health.
Dr. Swati Rajagopal, Consultant – Infectious Disease and Travel Medicine, Aster CMI Hospital, Bangalore shares, “When microbes such as bacteria, viruses, parasites, or fungi are transferred from animals to humans, zoonotic diseases occur. Transmission can occur via a wide range of means, including direct contact with infected animals, intake of contaminated food or water, acute exposure to infectious particles, or vectors such as ticks and mosquitoes. There is a wide variety of zoonotic diseases, including examples such as rabies, Lyme disease, and salmonellosis. Many zoonoses, however, are less well-known to the general public. The Nipah virus, which first appeared in Malaysia in 1998, for example, is spread to people from infected pigs or bats and can potentially cause respiratory and neurological symptoms.”
The frequent contact between humans and animals is one important factor that has contributed to the increase of zoonotic diseases. As human populations grow and intrude on natural habitats, the probability of encountering endangered animals and domesticated animals increases. Furthermore, climate change, agricultural intensification, and illegal wildlife trade all contribute to the spread of zoonoses.
Understanding the various zoonotic diseases is essential to successful prevention and control.
Bacterial Zoonoses: Brucellosis, leptospirosis, and Lyme disease are examples of bacterial zoonotic diseases. Coming into contact with infected animals, their urine, or contaminated environments can spread these diseases.
Viral Zoonoses: Famous viral zoonotic diseases include rabies, Ebola, and the recently discovered COVID-19. These diseases can be transmitted through direct contact with infected animals or by inhaling respiratory droplets.
Parasitic Zoonoses: Parasites such as Toxoplasma, Giardia, and Trichinella produce parasitic zoonotic diseases. These parasites can be spread by consuming contaminated food or water, coming into contact withinfected animals, or by vectors such as mosquitoes.
Fungal Zoonoses: Although less common, fungal zoonotic diseases can still be dangerous. Histoplasmosis and ringworm are two examples of diseases that can be spread through contact with contaminated soil, animals, or excrement.
Some zoonotic diseases are more common and pose a greater risk of human transmission.
Rabies: It is a viral zoonotic disease spread mainly through the bite of an infected animal, most commonly dogs or bats. It impacts the brain and spinal cord and is almost always fatal if left untreated.
Lyme disease: It is a result of the bacteria Borrelia burgdorferi and is transmitted to humans through the bites of infected ticks. This could cause flu-like symptoms, and joint pain, and can lead to more serious complications if not treated quickly.
Salmonellosis: It is a bacterial zoonotic infection that is commonly linked to contaminated food, particularly raw or undercooked eggs, poultry, and meat. It can cause diarrhoea, fever, and cramps in the abdomen.
Toxoplasmosis: It is induced by the parasite Toxoplasma gondii, which can be found in contaminated soil or in infected cat faeces. It is spread through the consumption of raw meat or unwashed fruits and vegetables. While most healthy people have mild or no symptoms, it can be dangerous for pregnant women and people with compromised immune systems.
Hantavirus Pulmonary Syndrome: Caused by inhaling particles from infected rodents’ urine, droppings, or saliva, such as mice and rats. The flu-like early symptoms include fever, muscle aches, and fatigue, followed by respiratory distress.
The symptoms and signs of zoonotic diseases can greatly differ based on the disease and the organ systems affected. Fever, cough, respiratory distress, diarrhoea, nausea, vomiting, muscle aches, and fatigue are all common symptoms. It is worth noting, however, that some zoonotic diseases can display asymptomatically or with mild symptoms, making early detection and prevention difficult.
The worldwide impact of the COVID-19 pandemic has highlighted the critical need for effective zoonotic disease control measures. COVID-19 is caused by the novel coronavirus SARS-CoV-2, but it shares characteristics with other zoonotic diseases. The virus is believed to have started in a wildlife market in Wuhan, China, where various animal species were sold. The lessons learned from COVID-19 can help us plan for future outbreaks. It is critical to improve early detection and surveillance systems in order to identify potential zoonotic threats as soon as possible. Furthermore, strengthening biosecurity measures in animal markets, farms, and wildlife habitats is critical to reducing disease transmission risk. Another crucial aspect of zoonotic disease control is collaboration between the human health, animal health, and environmental sectors. By encouraging interdisciplinary collaboration, we can gain a better understanding of the complex factors that contribute to disease emergence, devise effective prevention strategies, and respond to outbreaks more quickly.
Individual accountability and consciousness are the first steps in preventing zoonotic diseases. You can substantially reduce the risk of infection by implementing a few simple practices:
Maintain good hygiene: Hands should be washed with soap and water on a daily basis, especially after managing animals, visiting farms or animal markets, or cleaning pet waste. Hand hygiene is necessary to avoid the spread of zoonotic pathogens.
Vaccinate your animals: Ensure that your pets’ vaccinations are up to date, as several zoonotic diseases can be transferred from animals to humans. Regular veterinary examinations and precautionary measures such as flea and tick control are also required.
Handle food with caution: Meat should be properly cooked to destroy any potential pathogens and avert foodborne zoonotic diseases like salmonellosis. To avoid cross-contamination, use separate cutting boards and utensils for raw and cooked foods.
Protect against vectors: When spending a lot of time in areas with high vector activity, utilise insect repellents, wear protective clothing, and take precautions to avoid tick bites. This reduces the risk of zoonotic diseases like Lyme disease and West Nile virus significantly.
Inform yourself: Keep up to date on zoonotic diseases that are prevalent in your area. Recognize the symptoms of these diseases and seek medical attention as soon as possible if you suspect an infection.
Zoonotic diseases continue to be a significant threat to human health around the world. We can minimize the danger and safeguard ourselves and our communities by realising disease transmission mechanisms, learning from previous outbreaks, and taking preventative measures.
