Animal Diseases / Zoonosis - Dr. Srikant Sharma

Q1) What are Zoonotic diseases?

A) Zoonotic diseases are those which are transmitted to humans from animals. Those diseases and infections which are naturally transmitted between vertebrate animals and man. (Shakespeare, 2009).

Q2) What are the benefits of keeping pets?

A) Pets offer Comfort and companionship and we also love them as family members. The recent study found the famous” puppy dog eyes” glare triggers a whopping 300 per cent increase in owners Oxytocin levels - the ‘love hormone’ involved in maternal bonding. Household pets are associated with stronger social skills, in children with autism. Also, a study published in Circulation journal says, pet owners are with reduced risk of heart diseases.

Q3) What are Transboundary zoonotic diseases?

A) Defined as diseases that are of significant economic, trade and food security importance for a number of countries, which can easily spread to other countries and reach epidemic proportions, and where controlling needs cooperation between several countries. Emergency prevention system for animal health focuses on 12~14 diseases (foot and mouth disease, rinderpest, contagious bovine pleuropneumonia, sheep and goat pox, highly pathogenic avian influenza, Rift valley fever, Newcastle disease, rabies and African and classical swine fever).

Q4) What are the transmission ways of zoonotic diseases?

A) They are direct contact with diseased flesh( tularemia), eating insufficiently cooked meat( trichinosis),drinking raw or unpasteurized milk( tuberculosis), inhalation of dust contaminated with animal excreta( psittacosis ),bite of insect vectors carrying infection agents (plague), bite of disease animal (rabies).

Q5) What are the respiratory zoonotic diseases?

A) Anthrax, Brucellosis, Psittacosis, Q fever, Pasteurellosis, Melioidosis, plague (pneumonic) and Hantavirus, are spread by inhalation of aerosol.

Q6) What are hazards related to working with animals?

A) Hazards can be Physical,Chemical or Biological.

(1) Physical hazards include bite, kicks, crushing by animals. Domesticdog, foxes, raccoons, skunks, bats, cats or ferrets involved in human bite must be quarantined for 10 days observation to eliminate the risk of rabies transmission.

(2) Chemical: some Chemicals are introduced as part of experiment in animals. These are metabolized into different compounds and present in animals’ body fluids, urine, feces, bedding and caging equipment. Hence one should be familiar with safety details in handling these animals.
Most allergens are found in urine of rats, and urine, saliva and pelts of Guinea pigs. These allergens can cause sneezing, cough, Breathless, chest tightness, skin hives, occupational asthma (approximately 50% of the workers will go on to develop asthma) etc.

(3) Biological hazards include allergens produced by fur, saliva, danders or urine. Infections also can be exposed to infected animals to especially those humans who are immunocompromised.

• Campylobacter infection is caused by eating meat and eggs, or exposure to the stool of an infected animal (cat or dog). Campylobacter can cause abdominal pain, fever and diarrhoea. Around 49 per cent of dogs and 45 per cent of stray cats carry campylobacter in United States. Puppy and kitten (younger than six months) shed it in their faeces.


• Hookworm, roundworm and tapeworm are other biological hazards. The hookworm parasite can be shed through feces of animals, and humans contract it from the soil where such contaminated faeces are present. Cutaneous larva migrants caused by hookworm larva penetration to injured skin, causing red itchy and painful rash. Hookworm can cause abdominal pain, diarrhea and anemia also.Toxocariasis(roundworms, infect more than 14% Americans) from dogs and cats feces are shed in the soil, where from if ingested, then infect the human. This can cause ocular toxocariasis (vision loss) abdominal pain, fatigue, and coughing.


• Reptiles are carrier of Salmonella. Simply by touching pet reptiles and ingesting this bacteria, humans contract this disease.Turtles are also culprits for salmonella. Turtles less than 4 inches were even banned in US by FDA, because of their high risk for transmission of disease among young children, elderly and immunocompromised.


• Parrot fever (psittacosis) is a bacterial disease (Chlamydia psittaci) that humans can contract through inhalation of birds’ secretions, including urine and feces.This can cause encephalitis, hepatitis and inflammation of other organs like pneumonia gastroenteritis etc.


• Leptospirosis (Weil's disease): Leptospira bacteria typically infect some farm animals, dogs, and rodents. Human can become infected with the bacteria if your eyes, mouth, nose, or your skin come into contact with: urine, blood, or tissue from an animal that carries the bacteria. You can also contract leptospirosis if you’re bitten by an animal that is infected by it.


• Toxoplasmosis can be contracted in humans, either by eating undercooked or contaminated meat or coming in contact with contaminated cat feces. (Felines are carrier for it).This manifest as Muscle aches, swollen glands. Eye and brain manifestations are also possible especially in immunocompromised persons, pregnant women, elderly and young children.


• Cat scratch disease is caused by bartonella henselae bacteria. Cats are carriers. Kitten (<1 year) by scratches, spread this bacteria to humans. After 3 to 14 days of scratch it manifests as local swelling pain and tenderness. Fever, headache, fatigue, anorexia are usual manifestation, rarely brain and heart may be involved. Children under 5 years and immunocompromised experience severe symptoms


• Q fever, People get infected by breathing in dust that has been contaminated by infected animals’ (sheep, cattle, goat, cat, rodents) feces, urine, milk, and birth products that contain CoxiellaBrunetti. Direct contact (e.g. touching, being licked) with an animal is not required to become sick with Q fever. People may also get sick with Q fever by eating contaminated, unpasteurized dairy products. Rarely, Q fever has been spread through blood transfusion, from a pregnant woman to her fetus, or through sex. This manifest as fever, drycough, breathlessness, joint and muscle pain, anorexia, nausea, vomiting and nose bleeding.


• Contagious ecthyma (orf) from mouth of infected sheep transmitted to humans causing focal skin lesions on hands.


• Avian influenza is a global threat to all countries who have poultry industries.


• Plague(Y.Pestis) transmitted by bite of flea that has fed on infected animal (e.g. rat). This transmits from person to person through aerosol(pneumonic). This also is a threat for bioterrorism weapon. If not treated in 24 hours mortality is high.


• Anthrax is a respiratory zoonotic disease in tribal community. Mortality with or without treatment respectively is less than 1 and 20%.


• Tularemia (aka rabbit fever) occurs in moist climate, mud and decaying animal carcasses in North America. Highly contagious disease with life threatening potential, if not treated.


• Lyme disease (erythema marginatum rash- spreading rash). Can spread from localized disease to systemic, involving heart, brain and joints etc.


• Rocky Mountain spotted fever usually in United States, tick-borne, manifest as triad of fever, skinrash (centripetallymoving) and headache. Usually occurs in spring and summer.

Q7) What are common viral hemorrhagic fever transmitted by zoonosis?

• Dengue transmitted by A. Aegyptus, prevalent in tropical /subtropical coasts, and manifesting joint, bone, and petechiae.


• Yellow fever transmitted by mosquitoes, prevalent in tropical Africa, South and Central America, manifesting hepatic failure and Blood oozing.


• Argentinian fever transmitted by rodents’ urine in South America manifesting petechiae.


• Crimean Congo fever transmitted by tick in Asia, Africa, Eastern Europe, manifests as petechiae.


• Ebola virus disease transmitted by monkeys’ body fluid in Central Africa manifesting blood oozing.


• Lassa fever transmitted by rat urine/ body fluid in West Africa manifesting as encephalopathy and ARDS.

Q8) What is Nipah virus disease?

A) Nipah virus discovered from Malaysia in 1988, there after detected from Singapore, India (2001, 2007and 2018), Bangladesh, Philippines (2014).It transmitted through respiratory, oral, nasal secretions and urine. Bats' saliva contaminate fruits, and if that fruit is eaten by human, Nipah virus is transmitted. It can manifest as respiratory (ARDS, pneumonia), encephalopathy and Cardiac (myocarditis).It has very high mortality, in recent Kerala Nipah attack, out of 18 only 2 survived.

Q9) How to be safe from Zoonotic diseases?

• Hand hygiene is the key. Wash hands with soap and water for minimum 5 minutes after handling with pets’ saliva, feces and urine.


• Wearing protective clothing such as face mask, face shield, gloves, laboratory coat, and wearing goggles while handling animals. Leaving these coverings at the workplace to avoid problems for family members.


• Bites or scratches should also be washed with soap in running water for a minimum of 15 minutes followed by application of Betadine or tincture of iodine followed by spirit wash.


• Pet’sfeces disposal should be quick. Don’t sweep animal excreta without wearing mask and protective gear.


• Rabies vaccine should be taken for scratches or leaks over open skin areas and in addition specific immunoglobulin also should be taken if blood has come out or animal bite grade 3 lesion (also bats secretion inhalation).


• Get the pet vaccinated.


• Prophylactic immunization should be done against tetanus, influenza, typhoid Vaccine with Q fever is advised for persons working with large handling milk plants, wool, hides, and bones, entrails from cattle, sheep or goat. Brucella vaccination for Mongolians.


• Avoid applying contact lens while around animal’s. Avoid rubbing face or eyes with contaminated gloves and hands.


• If a worker is having severe Life-threatening allergic reaction, he should be strongly advised to change job, since no prevention strategies is completely effective.


• Modification of ventilation and filtration systems is done by increasing the ventilation rate and humidity in the animal housing areas.


• Increasing animal density (number of animals per cubic meter of room volume) is also helpful.


• Keep animal areas and cages clean.


• Bathe and groom your dog regularly. Broad spectrum deworming given on regular basis.


• Use flea and tick control product regularly.