CHAPTER SEVEN Prevention and control of

zoonotic diseases

Outline

Instructional ObjectiveIntroductionSpecific description of zoonosis

Instructional objective

At the end of this session students will able to

1. List at least four common zoonotic disease

2. Describe the common means transmission

3. Discuss common prevention and control

methods of zoonotic disease

4. Discuss management approaches of zoonotic

disease accordingly

IntroductionZoonosis

Communicable diseases common to man and

animals

Causes significant morbidity and mortality.

For most the diseases, human is a dead end

of the transmission cycle.

Introduction cont’d common types of zoonotic disease When animals used as a food

TaeniasisBrucellosis Trichinellosis or trichinosisToxoplasmosis

Animal Bite diseasesRabies

Direct contact diseases Anthrax

Animal reservoir diseasesLeishmaniasisAfrican Trypanosomiasis

Anthrax An acute bacterial disease primary of grass eating animals, and occasionally infect human. In human ,it primary affects skin but very rarely lower respiratory tract ,oropharynx, mediastinum or intestinal tract.

CauseBacillus anthracis

ReservoirAnimal normally herbivores

Anthrax-Mode of transmission

Occupational Hazard of workers who process

Hides

Hair

Bone and bone products

Anthrax-Mode of transmission Coetaneous anthrax

¨ contact with tissue of animals dying of anthrax

¨ Bite of flies that had partially feed on such animal

¨ Contaminated materials.

In halation Anthrax

Inhalation of spores in risky industrial process

Intestinal or oropharyngeal anthrax

Ingestion of contaminated meat

Anthrax cont’d IP

Few hours to seven days, most cases 48 hr.PCTransmission from person to person is rare,

but contaminated article remain communicable for years

Susceptibility and resistance Uncertain

Anthrax-C/M

Cutaneous Anthrax 95% of the cases At first small red maculs appear on exposed areas, head,

neck, face, then to papule that changed to blackened necrotic centre surrounded by highly expanding zone of oedema

Pain less swelling, Extensive oedema, no fever Non specific pain full regional L/Adenopathy 80-90% spontaneous healing with persistent oedema 10-20% infection progress & with high fever and rapid

death.

Cutaneous Anthrax

Anthrax-C/M

Inhalation anthrax

Mild symptom of URTI (early sign)

Acute phase occur after 1-3 days with increasing

fever, dyspnoea, stridor, hypoxia, and hypotension

usually leading to death with in 24 hr.

High fatality rate

Anthrax-C/M Gastro intestinal anthrax

Early sign: vomiting , watery& bloody diarrhoea

Variable fever, abd pain

sometimes rapid developing ascetics.

Oropharyngeal anthrax

Fever, sore throat ,Dysphasia

Painful regional L/Adenophathy

Primary lesion most often on tonsil

Respiratory distress

Anthrax-Dx

Clinical data

Lab Dx from fluid of vesicle, sputum and stool

Gram stain

Culture

Anthrax-RX

Penicillin G 10Mu IV daily

or

TTC 2gm PO daily for two wks

Clean & cover the Cutaneous lesion

Prevention & Control of Anthrax ¨ Decontamination of wool and goat’s hair or

others ¨ Improvement of working condition of animal

product ¨ Vaccination of susceptible groups & animals ¨ Treat all exposed animal.¨ HE

Brucellosis (Undulant Fever) A systemic bacterial disease with acute onset

transmitted to humans from infected animalsAgent B. melitensis acquired primary from goats, sheep, and

camel B. abortus from goats B. suis from pig B. canis from dogs They are aerobic gram –ve bacilli, intercellular parasite Reservoir Cattle, goat sheep, dogs

Brucellosis cont’d MT

contact with tissue, blood, urine, vaginal discharge aborted

foetuses especially placentas

Ingestion of row milk most commonly

Ingestion of diary products from infected animal

Air born infection those working in Abattoirs

Brucellosis cont’d

IP

1-3 wks or longer

PC

No evidence from person to person

Brucellosis-C/MAbrupt onset of fever, chills, diaphoresis, head ache,

myalgia, fatigue ,anorexia, joint pain sore throat dry cough

Spinal tenderness

Hepatospleenomegally

Asymmetric poly arthritis (knee, hip shoulder,)

Epididymo orchitis

Skin rash, Cardiac murmur, Pneumonia

Multiple organ involvement

Brucellosis cont’d DX

Clinical features with history of exposure or contact

Blood or bone cultures

RX

Doxy + aminoglycoside for 2wks

Doxy + refampicin for 4-8 wks

Bactrim + Refampicin in children <7 years and pregnant mother

for 8-12 wks

Prevention & Control Brucellosis

Elimination of disease in domestic animals

HE

Proper disposal system

Animal examination and Rx

Toxoplasmosis

Chronic or acute systemic Protozoal disease caused by

Toxoplasma gondii

Reservoir:Cats

MT

Ingestion of cyst in raw &under cooked meat.

Ingestion of Oocyte in food, drink, or from hands contaminated

with faeces of infected cat.

Transpalcental

Organ donation

Toxoplasmosis cont’d

IP

10-23 days

PC

Not directly from person to person except

transpalcental

Toxoplasmosis-C/m

Acute form Chills, Fever, head ache, myalgia , fatigue lymphadenitis Maculopapular rash Encephalomyelitis Retinochorditis that may leads to blindness

In infected child if transpalcental/ congenital Hydrocephaly Convulsion Motor disturbance

Toxoplasmosis cont’d DX C/m Cell cultureRX:-Pyrimethamine 100-200mg PO daily followed by

maintenance dose 25mg PO/d for 4 wks. Note – Rx indicated in sick immunocompromised caseFolinic acidPrevention & Control

Eat cooked meat and animal products (60c)

Rabies An acute viral disease of CNS invariably fatal Affect all animals Transmitted by infected secretion mainly saliva.

AgentRabies virus (lyssavirus)ReservoirDog, rats

Rabies cont’d

PC :Usually 3-7 days before the onset of the disease and

throughout the course of disease.

MT

¨ Transmitted with saliva of infected animal and introduced to

body by bite or scratch

¨ Occasionally inhalation, ingestion and tissue transplantation

but unusual

IP: 3-8wks (40 days)

Rabies cont’d

Pathogenesis

A bullet shaped virus which has many strain recovered from

rabid street dog called “street virus”

The virus multiplies in muscle at site of inoculation then

ascends along the nerve to CNS where from it subsequently

spread to all parts of the body via emerging net work of ANS.

Entrance to saliva propagates transmission

Infected animal identified as Negri body in 80% cases

Rabies cont’d Classification of animal bite

Class I Abraded skin, scratches that bleed

Class II Bite any part of the body other than head, neck &fingers None ulcerated wounds less than 5 in number

Class III ¨ All cases of bite on finger, hand or neck ¨ Wounds >5 anywhere on the body ¨ Lacerated wounds ¨ All cases bitten by wild animal

Rabies -C/MProdormal phase

Head ache FeverNausea Abnormal sensation at site of inoculation

Excitatory phase or Aerophobia ¨ Slight sound and wind excites the victim ¨ Irritability restless, nervousness ,tendency to bite Paralytic phase (full blown rabies) Spasm of swallowing muscle leads to drooling of saliva and fear of

water (hydrophobia) Delirium Convulsion Death due to respiratory muscle paralysis

Rabies -DX

History of bite by known rabid animal Nigri bodies

Rabies -RX1. Wound care Wash the wound with soap and water Stop bleeding, Cover the wound Never stitch as it may facilitate the spread 2. TAT 3. Anti Rabies vaccination 5ml S/C (preumbilical area) daily for 14 days

and two booster doses on 14th and 30th days

Rabies -RX

Indication for anti rabies vaccination Bite from known rabid animal or contact with

salve to lesioned tissue The animal escaped The animal show clinical pictures after 10 days

observation The animal died

4.Sadation if necessary

Rabies -Prevention and control

Immunize all dogs and cats

Detain & clinically observe for 10 days any unhealthy

appearing dog or cat known to have bitten a person

Post exposure prophylaxis

Keep dogs and cats at home

Destroy stray animals where rabies is endemic

Kill rabid animal.

Trichinellosis or Trichinosis Trichinosis is a disease caused by intestinal round worm whose

larvae (trichinae) migrates to and become encapsulated in the

muscles

Infectious agent

Trichinella spiralis, an intestinal nematode

Epidemiology

Occur worldwide, but variable incidence, depending in part on

practices of eating and preparing pork or wild animal meat.

Trichinellosis-cont’d

Reservoir

Swine, dogs, cats, horses, rats and many wild

animals, including fox wolf etc

Mode of transmission

By eating raw or insufficiently cooked flesh of

animals containing viable encysted larvae

Trichinellosis-cont’d

I/P

Systemic symptoms usually appear about 8-15

days after ingestion of infected meat.

Susceptibility and resistance

¨ Susceptibility is universal.

¨ Infection results in partial immunity

Trichinellosis-Clinical manifestations

Infection ranges from mild febrile illness to a severe progressive illness with multiple system involvement.

Fever(low-high grade)

Muscle pain mainly up on movement

oedema and spasm (periorbital and facial|)

photophobia and conjunctivitis

Weakness ; pain on swallowing

Dyspnoea , coughing and hoarseness

subconjuctival, retinal and nail splinter haemorrhage and rashes

Diarrhoea abdominal cramps, nausea and vomiting.

Trichinellosis-Clinical manifestationsInflammatory reactions around larvae that

reach tissues other than muscles may result in: ¨ Meningitis¨ Encephalitis ¨ Myocarditis¨ Bronchopneumonia¨ Nephritis¨ Peripheral ¨ Cranial nerve disorders

Trichinellosis - Diagnosis

Hx of ingestion of raw or inadequately cooked pork

Larvae in muscle biopsyPositive serologic test Oesinophilia

Trichinellosis -Treatment

Hospitalization of the PtMebendazole or Albendazole or

ThiabendazoleHigh dose of corticosteroids for 1-2 days

followed by lower doses for several days or weeks. But not for intestinal stage.

Trichinellosis-Prevention and control

Educate the public on the need to cook all fresh pork and pork products and meat from wild animals

Freezing of pork and its products inactivates trichinae

Summary

1. List at least four common zoonotic disease

2. Describe the common means transmission

3. Discuss common prevention and control

methods of zoonotic disease

4. Discuss management approaches of

zoonotic disease accordingly