Common Disease Of Human And Animal Population (Zoonotic Diseases)

Pashu Sandesh, 05 May 2022

VAIBHAV BHARDWAJ¹*, GAURAV KUMAR²

¹Department of Veterinary Surgery and Radiology, International Institute of Veterinary Education and

Research, Rohtak, Haryana, India

²Department of Veterinary Surgery and Radiology, College of Veterinary Sciences, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India.

 A zoonosis (zoonotic disease) is an infectious disease shared by both animal and human populations which are mainly caused by bacteria, viruses and parasites. Some zoonotic diseases don’t make the animal sick but affect the human. Zoonotic diseases range from minor short-term illness, which causes some minor clinical signs, to major life-threatening illness which may cause serious health problems. Certain diseases can cause death in both man and animal. Zoonotic diseases can be transmitted to humans in many ways:

• By air
• By consuming contaminated meat, milk or products
• Close contact with an affected animal
• Body secretions of an infected animal
• Through bites of some insects like mosquitoes or ticks

Bacterial diseases

1. Brucellosis

Brucellosis is a bacterial disease caused by a bacteria from the genus Brucella. Both humans and animals can be affected. Domestic and pet animals can spread brucellosis, including goats, cattle, and dogs. Most cases of human brucellosis are caused by B. melitensis and mainly affect sheep and goats. The bacteria can be transmitted through ingestion of raw milk or meat (eating), inhalation (through the air), or through an open wound. The clinical signs and symptoms of brucellosis in humans may develop from some days to months after the initial exposure to the bacteria. Clinical signs may vary from inpidual to inpidual. Some may develop mild symptoms, while others may develop long-term chronic symptoms. They include intermittent or relapsing fever (common sign), sweating, body aches, joint pain, weakness, dizziness, headache, irritability, loss of appetite, cough, difficulty breathing, chest pain and abdominal pain.

2. Listeriosis

Listeriosis is a bacterial food-borne disease caused by Listeria. It often affects pregnant women, newborns, the elderly, and immunocompromised people. These bacteria are most commonly present in foods such as unpasteurized milk products, raw meats and raw vegetables. Listeriosis causes miscarriage or stillbirth in pregnant women. In some cases, if the baby survives, it may develop a serious life-threatening infection of the brain or blood. The symptoms of Listeria infection are likely to last for 1-3 days like muscle aches, fever, flu-like symptoms, nausea, diarrhoea etc.

3. Bovine tuberculosis

Bovine tuberculosis (TB) is a chronic bacterial disease of animals caused by Mycobacterium bovis and is closely related to the human and avian tuberculosis bacteria. All mammalian species could be affected by TB, causing a general state of illness, weakness, coughing and eventually death may occur. The tuberculosis word denotes nodules or tubercles which occur in the lymph nodes of affected animals. The disease is highly contagious and spread by contact with infected animals. The common route of infection is by inhaling infected droplets through coughing from an infected person. Ingesting raw milk of infected cows could be a possible source of infection in calves and men. The main symptoms of active TB are achronic cough with blood-tinged mucus along with fever, night sweats and weight loss. Others may include chest pain and a prolonged cough producing sputum. A tuberculosis infection most commonly involves the lungs (in about 90% of cases).  Infection in organs, other than the lungs, can cause a wide range of symptoms. 

Viral diseases

1. Bird flu

Bird flu, also known as avian flu or avian influenza, refers to different strains of influenza that mainly affects wild as well as domesticated birds. Humans may also get bird flu from direct contact with affected birds (mainly chickens) or their infected droppings and body secretions. The chances of getting an infection in the human population are mainly by caring for infected birds, killing infected birds, and preparing infected birds for consumption. Clinical symptoms may occur two to eight days after exposure. An infected person experiences typical flu-like symptoms like fever (more than 38^◦C or 100.4^◦F), feeling unwell (anxiety), cough (usually non-productive), sore throat, muscle aches and/or pain, nausea, vomiting, diarrhoea, headache, joint pain, lethargy, nasal secretions (runny nose or sneezing), insomnia, and eye infections (conjunctivitis).

2. Rabies

Rabies, one of the most popular viral diseases, primarily infects mammals. Transmission of animal rabies and human rabies is similar, with virus-laden saliva from infected animals entering the body through bite wounds or by direct contact with unprotected mucosal surfaces. This virus is usually transmitted through a bite. Dog rabies (most common) is characterized by clinical manifestations, including abnormal behaviour of the dog, such as biting without provocation,  eating abnormal non-consumable items such as sticks, nails, faeces, etc., running for no apparent reason, vocal changes (like hoarse barking and growling) or inability to produce sounds, excessive salivation or foaming from the mouth. The early symptoms of rabies in humans may be very similar to those of the flu and may persist for a few days. Later signs and symptoms may include fever, headache, anxiety, confusion, hyperactivity, difficulty swallowing, excessive salivation, fear brought on by attempts to drink fluids because of difficulty swallowing water, hallucinations, insomnia and lastly partial paralysis, coma and death.

3. Japanese fever

Japanese encephalitis (JE) is a serious viral disease transmitted by mosquitoes. Equines (mainly horses) are the primary affected domestic animals of JE though essentially a dead-end host; other equids (like donkeys) are also susceptible. The actual transmission of the JE virus occurs by means of mosquito bites (principally Culex spp.). Culex tritaeniorhynchus is more important as it has a variety of host range that includes birds, horses, swine and also humans. A person can get JE from the bite of an infected mosquito. Most human infections have limited or sub-clinical signs of illness. When clinical signs are present, they may have a quick onset of high fever, headache, and neck stiffness. Infection of the brain (encephalitis) can cause disorientation, tremors or convulsions (especially in newborn), paralysis and coma, in some cases, death. Infections are generally more serious in newborn and elderly people.

Prevention tips:

Zoonotic diseases are present everywhere in the world. One of the most effective ways of prevention is by creating food safety regulations. These regulations help to reduce the chances of getting a zoonotic infection from items you eat in a country.

There are also some other ways to prevent getting a zoonotic disease. These include the following:

• Wash your hands properly and regularly.
• Use some insect repellent or any effective methods to keep mosquitoes, fleas, and ticks away from the surrounding.
• Don’t eat, drink, or touch your eyes or face while you’re handling or in close contact with any animal.
• Practice safe food handling.
• Contact your veterinarian about appropriate flea and tick preventatives for your pets.
• Use gloves to handle an animal that is or appears to be sick.
• Avoid being bitten or scratched by an animal.
• Vaccinate your pet and take them for regular annual visits to the veterinarian.
• Don’t handle or approach any sick animal in the wild.