المحاضرات التأهيلية لاختبارات الوظائف الحكومية اليوم الاول

2. Bacterial and viral diseases

3. Tuberculosis
►It is a chronic diseases ( may acute or sub acute ) of man and
animals caused by mycobacterium tuberculosis.
There are 3 common types of tubercle bacillus:
1- Human type  M. tuberculosis
This affects man, cattle and pigs ( lesser extent ) it is only of
importance in animals as it causes reaction to the tuberculin test
in cattle.
2- Bovine type  M. Bovis
This affects man, cattle and pigs. It is most virulent for cattle and pigs.
3- Avian type  M. avium
This affects birds, pigs and to a much lesser extent cattle and sheep.

4. Tuberculosis
►It is interesting to note that sheep are rarely infected with T.B.
There is a fourth type which affects fish
mode of infection:
1- Respiration
2- Ingestion
3- Inoculation
4- Genital
5- Congenital

5. Lymph nodes
T.B. can remain viable
 over 2 year in frozen carcass (-9C).
 18 day in pickled meat.
 167 days in decomposed lungs as decomposition has no
effect

6. Pathogenesis
●Infection of animals especially T.B.  digestive system (pig) or
respiratory (cattle)  exudation of fluid + involvement of Reg.
l.n . Or ●if bacilli are few in number.
●less in virulence.
●if the defensive powers of the body are high  T.B.
undergo necrosis, cassation and calcification  primary
infection ( Chronic form  chronic generalization )  raises the
body resistance against a second infection. ( Allergic resistance )

7. Pathogenesis
►When the defensive power of the body is low  Reification
exogenous and endogenous  ● Acute haematogenous
military T.B.
Chronic localized organ T.B.
Chronic isolated organ T.B.
►Chronic isolated organ T.B.
a- chronic acino nodular T.B of the lungs.
b- lung cavitation.
c- chronic T.B of the udder.
d- chronic T.B of the testes.

8. Pathogenesis
►Spreading of T.B by pre –existing channels.
( Bronchi- milk ducts- semen porous tubule)
● lymph or blood stream is not invaded.
●L.n is not infected  but if infected  primary infection.
Reinfection  acute late generalization
Stress factor  body resistance  virulence, profuse
exudation  dilute bacteria  spreading via pre – existing
channels, lymphatic or haema-togenous channels

9. Break down of T.B
1- multiple lobular caseous pneumonia.
2- acute acinonodular of the lungs.
3- caseous pleurisy.
4- caseous nephritis.
5- caseous metritis.
6- caseous mastitis.

10. Break down of T.B
 Macroscopically appeared as dry cascous masses
interspersed with blood spots + regional L.n. 
continuous supply of T.B.  blood.
 ►T.B. in pigs.
 (Bovine Type)
 Primary infection  digestive system of tonsils sub
maxillary L.ns  ●lesion may be healed.
Or break down Lymph heamatog enous generalization
 Miliary T.B.

11. Break down of T.B
►Avian T.B. in pigs:
● tissue reaction is of production type .
Tumour like lesion (no cassations or calcification)
● L.ns are enlarged, firmer, no tubercle.
In later stage small discrete yellow foci or large areas of
necrosis at the centre of L.n (early enucleated from L.n ).

12. T.B. of different organs and tissues
1-T.B. of lungs:
a- Isolated encapsulated and calcified foci:
When the primary lesion present a limited area of bronchi
pneumonia +regional L.n  healing  fibrosis + calcify.
b- Chronic acino-nodular and cavitation:
When scattered case us foci of various sizes involving the
acini of one or both lungs and emoceses by fibrous C.T
separate it from surrounding healthy tissues  chronic
acinened .

13. T.B. of different organs and tissues
 lung cavitations: are example of chronic organs T.B. and
caused by reinfection via spreading though the bronchi
the blood or lymph and L.n are free. If the lesion present
in L.n  old and calcified  primary inf.
 L.c. appear as solid cereous area  liquefied enter
the main bronchus cavity in the upper caudal parts of
the main lung lobes the cavity has a congested wall
and contain yellow-ish purulent material.

14. T.B. of different organs and tissues
 T.B. areas in lungs are surrounded by healthy pulmonary
tissue or zone of hepatization.
c-Acute acino-nodular :
As caseous foci of even distribution of one or both lungs 
break down of body resistance  spreading 
● localized ● haem
►haematog enous spread:
L.n is show signs of recent infection
Military T.B. are seen the lungs, liver and kidney cortex.

15. T.B. of different organs and tissues
►localized spread:
a- L.n is either free or show old calcified lesion  primary
infection.
b- no military T.B. in the lungs or else where.
c- caseous pneumonia:
this mean coalescence of caseous lung tissue,
interspersed with blood spots these areas sharply
separated from the healthy tissues by a zone of
inflammation  encapsul.

16. T.B. of different organs and tissues
► Late generalization:
Its importance revealed to it lead to acute military T.B. of
both wng  regional L.n is unaffected.
The bacilli present in the blood and meat in 80-90% of
cases.
e- early generalization:Miliary T.B.  uniformly disturb
same age and size.
● The lungs are enlarged, heavy  edematous and
emphysematous ehanges.
● L.n. is quite enlarged show caseation of a stellate
appearance.
● Bacilli  muscle of blood in 70%

17. T.B. of different organs and tissues
► Tuberculosis tracheitis and laryngitis:
Appearas nodules or ● ulcer on mucous membrane.
● due to coughing of T.B. materials.
►T.B. of pig lungs due to avian bacilli:
●is of productive nature.
●especially caseation or calcification.
●lesion appear as metastatic tumours.
●L.ns are enlarged and appear unaffected pleura

18. T.B. of different organs and tissues
In cattle visceral T.B pleurisy is more common than the
parietal T.B pleurisy.
Methods of infection:
a- lung infection  direct lymphatic drainage visceral
pleura  pleural cavity.
b- Rarely by direct haematogenous spread:
c- Rarely from the peritoneum by lymphatics of the
diaphragm.
d- Rupture of lung lesion or thoracic L.ns.

19. T.B. of different organs and tissues
The acute from:
●It is mainly during late generalization.
●the pleura is thickened to 1 inch or more and composed
of a dry caseaus material interspersed especially blood
spots.
●massive entry of bacilli  blood stream  acute case
us pneumonia.

20. T.B. of different organs and tissues
The chronic form:
● in early stages nodules  soft, reddish velvety
granulation  enter in ehronic generaliz  coalese
forming large casrous.
Masses, varying in size  typical grapes form.
●the pleura is very much thickened.
●on section, there is dry caseous moss especially
calcified center.

21. T.B. of different organs and tissues
►In pig:
T.B. of serous membranes are not common in pigs.
●The lesions appear as :
Small, scattered nodules  grains  on palpation may
penetrate to the sub- pleural tiss.
●The lesions may be of the diffuse type.
Peritoneum
T.B. peritonitis occur either in caver or in adults .

22. T.B. of different organs and tissues
►In calves:
The infection  extension from a primary lesion from the
liver.
The lesions are found in the peritoneum and diaphragm
which in contact especially anterior surface of the live

23. T.B. of different organs and tissues
►In adults:
a-direct extension of infection from liver or uterus.
b-from pleura  peritoneum ( by lymphatle of the
diaphragm)
c-breakdown lesions of lungs  ingestion of massive
doses of bacini into the digestive tract  infection of
the mesenteric L.ns

24. T.B. of different organs and tissues
T.B. of pleura and peritoneum may occur especially
entery of bacilli into the systemic civeulation chronic
T.B. of pleura of peritoneum is not serious in
judgment.
The pericardium
T.B. pericarditis  extension of infection from T.B.
pleurisy.
T.B. appear as red velvety patches near the base of the
heart or as a caseous nodules involving the whole
pericardium.
T.B. lesions of the myocardium or the endocardium
are rare.