This document discusses zoonotic diseases, which are diseases that can be transmitted between animals and humans. It provides an overview of important factors for emerging zoonotic diseases, modes of transmission, etiology, laboratory diagnosis, control methods, and details several important bacterial zoonotic diseases including Brucellosis, Anthrax, Ornithosis, Leptospirosis, and Q-Fever. Laboratory diagnosis involves culture, microscopy, serology, PCR and other molecular methods. Control relies on prevention and treatment in humans and animals as well as controlling transmission routes.

1. ZOONOTIC DISEASES
PRESENTED BY
Dr Abhishek Kumar Jain
Assistant Professor
Microbiology department
JNU IMSRC Jaipur
1
Monday, September 21,
2020

2. OVER VIEW
 Introduction
 Important factors for emerging zoonotic diseases
 Mode of transmission
 Etiology
 Laboratory diagnosis
 Control of zoonoses
 Few important bacterial zoonotic diseases
2

3. INTRODUCTION
 Zoonoses are diseases and infections of animal.
 An infection or infectious disease that can
transmitted between animals and humans with or
without vectors.
 The FAO and WHO Expert Committee in 1967
defined zoonoses as “those diseases and infections
which are naturally transmitted between vertebrate
animals and man”.
3

4.  Anthropozoonoses : infection transmitted to man from
vertebrate animals.
 Ex- rabies, plague, hydatid disease, anthrax and trichinosis.
 Zooanthroponoses : infections transmitted from man to
vertebrate animals,
 Ex- human tuberculosis in cattle.
 Amphixenoses : infection maintained in both man and
lower vertebrate animals that may be transmitted in
either direction.
 Ex- T. cruzi, and Schistosoma japonicum
4

5. IMPORTANT FACTORS FOR EMERGING ZOONOTIC
DISEASES
1) The transportation of humans and animals to new
areas,
2) Increased contact between animals and humans,
3) Changes in the environment and husbandry practices,
4) A larger immuno-compromised population,
5) Increased recognition of diseases as zoonotic in origin,
and
6) The discovery of new organisms not previously
recognized. 5

6. MODE OF TRANSMISSION
1) Through animal bites and scratches;
2) Through direct fecal oral route, contaminated animal food
products, improper food handling, and inadequate cooking.
3) Farmers and animal health workers (i.e., veterinarians) are
at increased risk of exposure and could also become carriers
4) Via vectors, (arthropods), such as mosquitoes, ticks, fleas,
and lice can actively or passively transmit zoonotic diseases.
5) Soil and water recourses are contaminated with manure
contains a variety of zoonotic bacteria, creating a risk for
zoonotic bugs and immense pool of resistance genes
6

7. ETIOLOGY; A - BACTERIAL INFECTION
S. No. Disease in
Man
Animal principally
involved
Causative agent
1 Brucellosis Cattles, sheep, goats, camels ,
pigs, dogs, horses, buffaloes.
Brucella spp.
2 Anthrax Herbivores, pigs Bacillus anthrax
3 Ornithosis Wild and domestic birds Chlamydophila psittaci
4 Q-fever Cattles, sheep, goats, wild
animals, ticks.
Coxiella burnetii
5 Leptospirosis Rodents, mammals. Leptospira
6 Plague Rodents Yersinia pestis
7 Tuberculosis Cattles, sheep, goats, pigs,
cats, dogs.
Mycobacterium bovis 7

8. B- VIRAL INFECTIONS
S.
No.
Disease in Man Animal principally involved Causative agent
1 Rabies Dog, fox, mongoose, bat and jackal. Rhabdovirus
2 Cowpox Cattles Orthopoxvirus.
3 Monkey pox Monkey, and rodents. Orthopoxvirus.
4 Eastern equine
encephalitis
Horses, rodents. Alphavirus
5 Ross river fever Horses, cattles, goats, sheep, dogs, rats,
bats, pigs.
Alphavirus
6 Yellow fever Monkeys Flavivirus fibricus
(Group B- arbovirus)
7 Japanese encephalitis Wild birds Flavivirus
8 Lassa fever Multimammate rat Arenavirus
9 Kyasanur Forest
disease (KFD)
Monkeys Flavivirus
8

9. C- PROTOZOAN INFECTIONS
S.
No.
Disease in
Man
Animal principally
involved
Causative Agent
1 Leishmaniasis Dogs, cats, swine Leishmania donavani
2 Toxoplasmosis Cats, mammals, birds. Toxoplasma gondii
3 Trypanosomias
is
Cattles Trypanosoma spp.
4 Babesiosis Cattles Babesia microtii
9

10. D- HELMINTHIC INFECTIONS
S. No.
Disease in Man Animal principally involved
1 Taeniasis Pigs and Cattles.
2 Echinococcosis Dogs, wild carnivores, domestic and wild
ungulates
3 Clonorchiasis Dogs, cats, swine, wild mammals, fish.
4 Fasciolopsis Swine, dogs.
5 Schistosomiasis Rodents
6 Trichinellosis Swine, rodents, wild carnivores, marine
mammals.
10

11. LABORATORY DIAGNOSIS
 Laboratory diagnosis is important for the diagnosis
of zoonoses.
 Both in humans and animals, It is based on
 Isolation of causative agent.
 Microscopy
 Serology
 Autopsy
11

12. CONTROL OF ZOONOSES
 Control in animals:- it comprise-
 Diagnosis, treatment, destruction, quarantine and
immunization.
 Control of vehicles of transmission:- includes
 Establishment of food hygiene practices,
 Ensuring safety of animal products such as wool, hides,
horn, bones, fat etc. ;
 Proper disposal of animal carcasses and wastes, and
disinfection procedures. 12

13.  Prevention and treatment in man:- involves
 Protection of high risk groups by immunization,
chemoprophylaxis,
 Monitoring of health status including occupation health
programmes,
 Prevention of spread by man,
 Early diagnosis and treatment,
 Health education,
 Prevention of environment contamination
 Prevention of food contamination
 Improvement of diagnostic facility. 13

14. FEW IMPORTANT BACTERIAL ZOONOTIC
DISEASES
14

15. 1. BRUCELLOSIS
 Mediterranean fever, Malta fever and undulant fever
 Characterised by intermittent or irregular febrile
attacks, with profuse sweating, arthritis and enlarge
spleen.
 Agent- Brucella species.
 Gram negative, non-motile, non-sporing and intracellular
coccobacilli.
 Four species infect man are B. melitensis, B. abortus, B.
suis, and B. canis.
 Reservoir of infection- Goats, sheep, cattle, buffaloes,
swine, horses and dogs. Animal may remain infected
for life. 15

16.  Mode of infection- Acquired from animals, directly or
indirectly.
 Person-to-person spread does not occur.
1. Contact infection- (m.c.) by direct contact with infected
tissues, blood, urine, vaginal discharge, aborted foetuses and
especially placenta. Infection takes place through abraded
skin, mucosa or conjunctiva.
2. Food born infection- ingestion of raw milk, dairy
products(cheese), fresh raw vegetables, water contaminated
with infected animal excreta.
3. Air-borne infection
 Incubation period- highly variable, usually 1-3 weeks. 16

17. LAB DIAGNOSIS
 Specimen collection, transport, and processing-
 Isolation of organism in cultures of blood, bone marrow, CSF,
pleural and synovial fluids, urine, abscess or other tissues.
 Direct detection methods-
 Conventional and real-time PCR assays- reliable and specific
means of directly detecting Brucella organisms in clinical
specimens.
 Sensitivity varies among assays, ranging from 50% to 100%.
 Several gene targets have been used, including a cell surface
protein (BCS P31), a periplasmic protein (BP26), 16S rRNA,
and transposon insertion sequence 711(IS711). 17

18. CULTURE-
18
 Grow on blood and
chocolate agar.
 Brucella agar or infusion
base agar is recommended
for specimen types other
than blood.
 Incubate at 5-10% CO2 in
humidified atmosphere at
37oC. For up to 3 weeks.
 Castaneda method is also
used for blood culture.
Growth of Brucella spp. on chocolate agar

19. APPROACH TO IDENTIFICATION
 On culture, colonies appear small, convex, smooth,
translucent, nonhemolytic, and slighty yellow and
opalescent after at least 48hours of incubation.
 Brucella spp. are nonmotile, catalase, urease,
oxidase, and nitrate positive, and strictly aerobic.
 Particle agglutination test- The most rapid test for
presumptive identification of Brucella spp. with
anti–smooth Brucella serum
19

20. SERODIAGNOSIS
 Standard agglutination test (SAT)
 Microplate agglutination test (MAT)
 A titer of 1 : 160 or greater in the SAT is considered
diagnostic if this result fits the clinical and
epidemiologic findings.
 ELISA- purified LPS or protein extracts are used.
 Can detect IgG and IgM Abs.
 Rapid methods- rapid dipstick test (>90%
sensitivity) and Rose Bengal card test can be used. 20

21. 2. ANTHRAX
 Caused by Bacillus anthracis
 Reservoir of infection- cattles, and spores in soil.
 Gram positive, non-acid fast, non-motile, spore
forming bacilli of 3-10µm x 1-1.6µm size.
 Anthrax may be-
 Cutaneous anthrax- Hide porter’s disease
 Pulmonary anthrax- Wool sorter’s disease
 Intestinal anthrax- rare, violent enteritis with bloody
diarrhoea with high case fatality rate.
21

22. LAB DIAGNOSIS
 Microscopy
 Gram’s stain- Gram positive bacilli with characteristic
bamboo stick appearance.
 Sudan black B stain- fat globules seen with in the bacilli.
 Polychrome methylene blue- blood film stained for few
seconds and examined under microscope, an
amorphous purplish capsular material is observed-
M’Fadyean’s reaction is used for presumptive diagnosis.
 Immunofluorescent microscopy can confirm the
identification. 22

23.  Culture- on nutrient agar, blood agar, geletine stab
culture, or on selective medium (PLAT medium-
polymyxin, lysozyme, EDTA and thallous acetate added
to heart infusion agar).
 Inoculated plate incubated at 35-37oC aerobically for
overnight incubation.
Biochemically- they ferment glucose, maltose and sucrose
with acid production without gas, NR and catalase
positive.
 Animal inoculation
 Serological demonstration-
 Ascoli’s thermoprecipitin test demonstrate anthrax antigen in
tissue extracts. 23

24.  Serology for antibody-
 Gel diffusion, complement fixation, antigen coated
tanned red cell agglutination and ELISA test.
 Molecular methods-
 PCR with specific primers.
 MLST (multilocus sequence typing)
 MLVA (multiple locus variable number tandem repeat
analysis) or
 AFLP (amplified fragment length polymorphism)
24

25. 3. ORNITHOSIS OR PSITTACOSIS
 Agent- Chlamydiae psittaci or Chlamydophila.
 Reservoir- parrots and other birds.
 Lab diagnosis-
 Diagnosis of psittacosis is almost always by serologic
means.
 Laboratories with Biosafety Level 3 biohazard
containment facilities can culture C. psittaci safely from
blood (early stage) and from sputum (later stage of
disease)
 Cell culture is the preferred mode of isolation (McCoy
and HeLa cells are commonly used.
25

26.  Infected cell show inclusion bodies- Levinthal-Coli-
Lilli or LCL bodies.
 Diffuse and irregular, not stained by iodine and not
inhibited by sulphadiazine or cycloserine.
26

27.  Complement fixation
 Indirect microimmunofluorescence
 used to detect anti–C. psittaci antibodies
 fourfold rise in titer between acute and convalescent
serum samples, or
 a single IgM titer of 1 : 32 or greater considered
diagnostic of an infection.
 PCR assay - amplification of rDNA sequences
 Restriction fragment length polymorphism (RFLP)
analysis 27

28. 4. LEPTOSPIROSIS
 Weils disease is one of manifestation of human
leptospirosis.
 Agent- Leptospira interrogans
 Actively motile, delicate, flexible, helical rods about 6-20µm
long and 0.1µm thick.
 Visible by dark field illumination and silver staining.
 Source of infection- Excreated in urine of infected
animal for along time or entire life time in case of
rodent.
 Reservoir – cattles, sheep, buffalo, pigs and rats and
small rodents R. norvegicus and Mus musculus (m.c.)
28

29. LAB DIAGNOSIS
 Direct detection-
 Dark field microscopy of Blood, CSF, and urine directly.
 Leptospira exhibit corkscrew-like motility.
 Fluorescent antibody staining
 Hybridization techniques-using leptospira-specific DNA
probes.
 Conventional and real time PCR assay.
 Molecular diagnosis-
 PCR- not useful for serovars differentiation.
 PFGE (Pulsed field electrophoresis)
 RFLP 29
Useful for serovar
identification

30.  Culture- a)- Blood culture
 Can grow in media enriched with rabbit serum
 Korthof’s, Stuart’s, and Fletcher’s media and EMJH
(Ellingghausen, McCullough, Johnson, Harris) is
commonly used.
 Inoculated plate are incubated aerobically at 28-32oC.
 Examined by dark ground microscopy every third day
up to 6 weeks before discarding it as negative.
b)- Urine culture
 Urine should be inoculated soon after collection,
because acidity (diluted out in the broth medium) may
harm the spirochetes.
30
Note- addition of 200 μg/mL of 5-fluorouracil (an anticancer drug) may
prevent contamination by other bacteria without harming the leptospires.

31.  Serology- Serodiagnosis of leptospirosis requires a
fourfold or greater rise in titer of agglutinating
antibodies.
1. Microscopic agglutination (MA) test- using live cells is
the standard serologic procedure.
2. Indirect hemagglutination and
3. An ELISA test for IgM antibody are also available;
during the first week of illness.
 Molecular diagnosis
 Convensional PCR, real-time PCR, and
 Loop-mediated isothermal amplification.
 To date, no commercial molecular assays are available for
diagnostic use.
31

32. 5. Q-FEVER
 Agent- Coxiella burnetii is the causative agent of Q
fever, an acute systemic infection that primarily
affects the lungs.
 Pleomorphic coccobacilli with Gram negative cell
wall, occur as rods 0.2-0.4µm x 0.4-1.0µm or as
spheres 0.3-0.4µm in diameter.
 Is obligate intracellular pathogen, primarily
infecting monocyte-macrophage cells.
32

33. LAB DIAGNOSIS
 Diagnosis is by serology, as it culture is done in a biosafty level
3 containment facility.
 Sample– blood for microscopy, culture and serology
 Microscopy- blood or vegetation from heart valves is used to
prepare a smear.
 Smear is stained with Macchiavello’s stain- Coxiellae appear very
minute red coccobacilli.
 Culture-
 By shell vial assay with human lung fibroblasts to isolate the
organism from buffy coat and biopsy specimens.
 once inoculated, cultures are incubated for 6-14 days at 37oC in
CO2.
 Direct immunofluorescent assay used to detect it. 33

34.  Serology-
 Microagglutination
 Complement fixation
 Immunofluorescence
 ELISA
 Molecular diagnosis
 PCR- help to improve early diagnosis of acute Q fever.
34

35. 6. PLAGUE
 Also known as ‘black death’
 Agent- Yersinia pestis
 Is a short, plump, ovoid, Gram-negative bacillus, about
1.5 x 0.7µm in size, with rounded end and convex sides.
 Smear stained with Giemsa or Methylene blue- shows
bipolar staining (safety pin appearance).
 It is non-motile, non-sporing, and non-acid fast.
 Reservoir of infection- rodents
 Mode of infection-
 direct or via rat fleas (Xenopsylla cheopis)
35

36. LAB DIAGNOSIS
 Specimen-
 In buboni plague- buboes fluid.
 In pneumonic plague- sputum.
 In septicemic plague- blood is collected.
 Microscopy-
 smear of bubonic fluid and sputum is stained with
methylene blue (Wayson stain) to look for bipolar
staining.
 Culture- can grow on basal media. 36

37.  Blood culture are positive in apprx. 80% of bubonic
plague and 100% in septicemic plague patients.
 Serology-
 Direct fluorescent antibody test
 Antigen capture ELISA are specific tests.
 Four fold or greater change in antibody titer.
 Rapid diagnostic test-
 Simple dipstick test using monoclonal Abs to detect the
F1 antigen (protein) i.e. specific to Y. pestis. Gives
results within 15 min.
37

38. 7. BOVINE TUBERCULOSIS
 Mycobacterium bovis (M. bovis) is another
mycobacterium that can cause TB disease in people
 Found in cattle and other animals such as bison, elk, and
deer.
 M. bovis is now included in the M. tuberculosis complex.
 M. bovis are-
 Niacin- negative
 Nitrates not reduced to nitrites.
 Pyrazinamidase is not produced.
 Selective inhibition of growth by T2H; M. bovis will not grown
in medium containing T2H
38

39. LAB DIAGNOSIS
 Microscopy- sputum for AFB.
 Culture-
 On LJ media growth requires 6 to 8 weeks of incubation
 Medium most favourable to M. bovis contains 0.4%
pyruvate without glycerol.
 Note- Certain laboratory strain of M.bovis are
known as BCG (bacille Calmette-Guérin) .
 Used as vaccine in highly endemic area of world. 39

40. REFERANCE
1. Park’s textbook of Preventive and Social Medicine 19th Edition. P 242-
249.
2. Mandell, Douglas and Bennett`s Principles and Practice of Infectious
Diseases 7th Edition. P 3999-4007.
3. Koneman’s Colour Atlas and Textbook of Diagnostic microbiology. 6th
Edition.
4. Bailey & Scott’s diagnostic microbiology 13th Edition.
5. Textbook of Microbiology by Ananthanarayan, Paniker, Arti Kapil. 9th
Edition.
6. Isolation of Brucella melitensis from a human case of chronic additive
polyarthritis.*R Chahota, A Dattal, SD Thakur, M Sharma. Indian
Journal of Medical Microbiology, (2015) 33(3): 429-432.
40