Zoonotic Diseases, Community Health

1. Prepared by:
Mrs. Namita Batra Guin
Associate Professor
Community Health Nursing Department
Namita Batra Guin

3. ž Primarily a zoonotic disease. Caused by
Yersinia pestis, involving rodents and fleas.
ž Plague occurs in many forms- enzootically,
epizootically, sporadically and in epidemics
of all types.
ž HISTORY:epidemics are mentioned in Bible
also. It is also mentioned in Bhagwat Puran
that as soon as dead rat is seen the residence
should be immediately abandoned.
ž It was also known as “Mahamari”
ž Since the Christian era there has been 3
pandemics: in year 542, 1346, 1894which
continued till 1930.
ž In India, plague reappeared in 1994, after
the silent period of atleast 28years.
Namita Batra Guin

4. ž Agent: Yersinia pestis, gram-tive, non motile
cocco-bacilli. Occurs in abundance in blood, liver,
spleen and viscera of infected persons.
ž Plague bacilli can survive and multiplies in soil of
rodent burrows where conditions are favourable.
ž Reservoir of infection: wild rodents are natural
reservoirs of plague. Found in mountains, deserts,
cultivated areas and forests in temperate and
tropical regions.
ž In india, wild rodent, Tatera indica and Rattus
rattus are main reservoir.
ž Source of infection:infected rodents and fleas
and case of pneumonic plague.
Namita Batra Guin

5. ž Host factors: Age and sex: all ages and both
sexes.
ž Human activities: hunting, grazing,
cultivation, harvesting and construction
activities.
ž Movement of people and cargo by sea or land
may also be associated with plague.
ž Immunity:man has no natural immunity.
Namita Batra Guin

6. ž Environmental factors: season: in northern
india- september to may. The disease tends to
die out in hot weather. In south India, there is
no definite plague season. The disease was
found to be active all year round.
ž Temperature and humidity: mean temperature
20 to 25˚C and relative humidity of 60%
ž Rainfall: heavy rainfall.
ž Urban and rural areas
ž Human dwellings: where housing conditions are
poor, abundant rats, rat fleas all round year and
contact with man occurs readily.
Namita Batra Guin

7. ž Rat fleas are most common and efficient
vectors of plague.
ž Both sexes of flea bite and transmit the
disease.
ž A flea may ingest upto 0.5 cu mm of blood
which may contain 5000 plague bacilli.
ž They multiply in gut of rat flea which blocks
their proventriculus and no food can pass
through. It is unable to obtain blood meal, so
it makes frantic efforts to bite and suck
blood and in doing so transmit the bacilli.
ž Infected fleas can live upto an year.
Namita Batra Guin

8. ž Wild rodents: reservoir of plague in nature
common wild rodents are: Taetera indica,
Bandicota bengalensis and Mus booduga etc.
ž Commensal rodents: rodents which live close
to man. Futher divided into domestic and
peridomestic species. Domestic species
seldom live in fields. Peridomestic live in
both fields and houses. Rattus norvegicus
lives in sewers and is example of
peridomestic species in India.
Namita Batra Guin

9. Namita Batra Guin

10. Namita Batra Guin

11. ž Wild plague: it is defined as
plague existing” in nature
independent of human
population and their
activities. This spreads
among wild rodents by wild
rodent fleas.
ž Domestic plague: it is
defined as plague that is
intimately associated with
man and rodents living with
him and has a definite
potential for producing
epidemics.
Namita Batra Guin

12. ž Field rodents spread infection very slowly
from burrow to burrow, field to field.
ž In the process they infect village rats
(commensal rodents), especially the
peridomestic species.
ž Perodomestic species act as a liason rodents
between man and field rodents.
ž Outbreak of human plague is always
preceded by rat plague
ž After death of house rats, fleas leave the
rats and are forced to seek man for food.
ž Unusual mortality among rodents should
arouse the suspicion of plague.
Namita Batra Guin

13. ž Collection and forwarding of dead rats:rodents
found dead should be carefully packed in several
layers. Neck of the bag should be tied properly.
Should be placed in tin/ wooden box filled with
saw dust to eliminate chances of leakage of
effluents. Details are labeled and sent for
investigation.
ž Autopsy and collection of smears: rat is held
with pair of tongs and dipped in solution of 5%
cresol. Small portion of viscera are cut and
smears are made on slides. Smears are dried and
treated with alcohol and fixed by exposure to
open flame. And then it should be sent for
examination.
Namita Batra Guin

14. ž Animal inoculation: small portion of spleen
or liver are taken. Small portion are
inoculated in guinea pigs or white mouse. If
there is plague infection – guinea pig will die
in 7 days and white mouse in 48 hours.
ž Pathological changes: edema and necrosis at
site of injection, lymph nodes are enlarged,
spleen gets enlarged and congested and
shows necrotic patches. Liver shows
mottling, lungs shows necrotic lesions and
there is S/C congestion and hemorrhages.
Namita Batra Guin

15. ž Mode of transmission: human plague is
contracted from:
¡ Direct contact with the tissues of infected
animal.
¡ By droplet infection from cases of pneumonic
plague patients.
¡ By the bite of an infected fleas.
Namita Batra Guin

16. ž Commensal rats à rats fleas à man (basic
cycle in epidemic bubonic plague)
ž Wild rodentsà wild rodents fleas or direct
contact àman (by direct contact).
ž Wild rodents, peridomestic rodents,
commensal rodent àwild rodent fleas,
peridomestic rodent fleas, commensal rodent
fleasà man (interaction of rodents and their
fleas convey the infection to man).
ž Manà human flea (Pulex irritans) à man
(variety may encountered in certain areas)
ž Man àman (in case of pneumonic plague).
Namita Batra Guin

17. ž Bubonic plague: 2 to 7 days.
ž Septicemic plague: 2 to 7 days.
ž Pneumonic plague: 1 to 3 days.
Namita Batra Guin

18. ž Bubonic plague:
¡ most common type.
¡ Infected fleas usually bite on lower extremities
and inoculate bacilli.
¡ Bacilli proliferate in lymphatic region.
¡ Patient develops sudden fever, chills, headache,
painfull lymphadenitis.
¡ It cannot spread from person to person as bacilli
are locked up in buboes and do not find way.
Namita Batra Guin

19. ž Pneumonic plague:
¡ Primarily rare.
¡ Generally follows as complication of bubonic-
septicemic plague.
¡ Highly infectious
¡ Spreads from man to man by droplet infection.
¡ Plague bacilli are present in the sputum.
Namita Batra Guin

20. ž Septicemic plague:
¡ Primarily rare except for accidental laboratory
infections.
¡ Bubonic plague may develop into septicemic
plague.
Namita Batra Guin

21. ž Staining: smear is prepared from the clinical
material (e.g. bubo fluid, sputum) which
should be fixed with alcohol and then stained
with Giemsa stain to demonstrate bipolar
bacilli.
ž Culture: under ideal circumstances
appropriate culture media should be
inoculated on spot to ensure speedy isolation
of plague bacilli. Otherwise it should be
transported to lab in Carry Blair transport
medium.
ž Serology: acute and convalescent specimens
of blood sera is collected for study.
ž Others: include inoculation of guinea pigs or
mice or immunoflourosent microscopic test.Namita Batra Guin

22. ž Early diagnosis: acute fever and painful
lymph node enlargement developing into
buboes in the inguinal region.
“Rats falls” also provide useful warning.
Diagnosis is made by examining the smears
that shows bipolar stained plague bacilli.
ž Notification: case notification is required by
International Health regulations.
ž Isolation: all cases of pneumonic plague
require isolation. Bubonic plague cases are
also recommended isolation.
Namita Batra Guin

23. ž Treatment: must start without waiting for
confirmation of diagnosis. Drug of choice is
streptomycin 30mg/kg body weight. It is
given I.M. in 2 divided doses for 7 to 10 days.
Tetracycline is an alternative drug given
orally in dosage of 30-40mg/kg body weight.
ž Disinfection: disinfection of sputum,
discharges and articles soiled by the patient
should be carried out. Dead bodies should be
handled with aseptic precautions.
Namita Batra Guin

24. ž DDT and BHC dusts containing 10% and 3% of
active ingredient respectively.
ž In areas of resistance to one or both, dusts of
carbaryl(2%) or malathion (5%).
ž Spraying is done covering entire floor area,
bottoms of all walls upto 3 feet above floor
level, back of doors, roofing, crevices of
walls, clothings, bedding, cats, dogs and
other pets.
ž Rat burrows to be insufflated with
insecticidal dust.
ž Flea index should drop down within 48 hrs of
application. Spraying should be done up to
radius of 5 miles around each infected
locality. Namita Batra Guin

25. ž By proper sanitation measures-
¡ Proper storage, collection and disposal of
garbage.
¡ Proper storage of food stuffs
¡ Construction of rat proof buildings, godowns and
warehouses.
¡ Elimination of rat burrows by blocking them with
concrete.
ž Trapping: trapping the rats is simple
operation. Captured rats must destroyed.
ž Rodenticides: single dose and multiple dose.
Commonly used are: barium carbonate, zinc
phosphide (extensively used in India).
Multiple dose poisons- warfarin, coumafuryl
etc. Namita Batra Guin

26. ž Fumigation: fumigants used are- calcium
cyanide (cyanogas), carbon disulphide,
methyl bromide, sulphur dioxide etc.
ž Cyanogas is extensively used in India. 2
ounces of poison are pumped in rat burrows
after closing exit and then burrow is
promptly sealed with wet mud.
ž Chemosterilants: chemical that can cause
temporary or permanent infertility in either
sex or both sexes. They are still in
experiment stage.
Namita Batra Guin

27. ž Vaccination should be carried out a week
before an anticipated outbreak, and vaccine
should be given in 2 doses.
ž Vaccine is given S/C in two doses of 0.5 and
1.0 ml at an interval of 7 to 14 days.
ž Immunity lasts for about 6 months
ž Booster doses are recommended to persons
at continuing risk of infection.
Namita Batra Guin

28. ž Chemoprophylaxis is offered to all plague
contacts.
ž Drug of choice is tetracycline. Adult dosage-
500mg 6 hourly for 5 days.
ž Another drug –sulfonamide, 2-3g daily for 5
to 7 days.
Namita Batra Guin

29. ž Surveillance should cover all aspects of
rodent and human plague e.g. microbiology,
serology, entomology, epidemiology and
ecology.
ž On basis of information provided by
surveillance, effective control measures must
be established.
Namita Batra Guin

30. ž Locality an administrative area shown on
map.
ž Date of first case noticed.
ž Period of investigation.
ž Number and type of plague cases.
ž Contacts of known cases (serological and
throat swab results)
ž Chemotherapy applied
ž Vertebrate host population – wild, domestic
rodents.
ž Vector population- identification, lab.
Results, insecticide results, control measures
applied.
Namita Batra Guin

31. Namita Batra Guin