Lecture 9 the infectious disease

Prof.Dr.
Khalil Hassan Zenad
Aljeboori
Copyrights©2017lAliraqiaUniversitylDentistrylPathologylProf.Dr.KhalilHassanZenadAljeboori.
THE INFECTIOUS DISEASE
Lecture 9

Viral diseases :
Rhinoviruses and influenza viruses :
Responsible for common cold , both RNA viruses type A,B,C, both types caused
pandemic infection 1918, it contain both hemagglutinin and neuraminidase
mutation of these protein resulted in to escape of virus from the antibodies
(antigenic drift)
Avian influenza (bird flu) H5N1 cause massive outbreak in poultry and jump
to human and cause outbreak. An outbreak at 2009 in virus H1N1 an epidemic
of a new strain referred to as swine flu. The resulted mutation of (4) strains of
influenza virus A H1N1 an endemic in human and endemic in birds and two
endemic in pigs in both the rhinitis , sinusitis , otitis media , Pharyngitis,
tonsillitis , tracheitis , bronchitis , bronchiolitis , and secondary bacterial
infection by Streptococcus Pneumonia .
Some human infections diseases

Herpes virus DNA, HSV-1, HSV2 neurotropic virus , replicate in skin and mucous membranes at the site
of entrance of virus ( oropharynx or genitalia ) cause vesicular lesions and infect neuron of the location
. the virus remain in nerve cells latent and reactivate and infect skin and mucous membrane. Cells form
multinucleated syncytia containing inclusion of virus particles diagnostic in smear of the blisters fluid .so
the viral infection clinically show fever blisters (cold sore) . intraepithelial vesicle ( hydropic
degeneration) of skin around the lips , nose , burst ,crust formation at the vesicles. The forms of viral
infection include:
1-Gingivostomatitis . vesicles in mouth, tongue, pharynx. (HSV-1)
2-Genital herpes vesicles seen at genital mucosal layer and external genitalia, associated with
ulceration and rimmed by inflammation (HSV-1,2) neonates will affected during delivery in neonates ,
splenomegaly liver lesion , lymphadenopathy, CNS lesion .
3-Herpetic eye infection
A- Herpes epithelial keratitis lysis of corneal epith.
B-Herpes stromal keratitis due to immunological reaction to viral infection
4-other herpetic infections :
Herpes encephalitis , Kaposi sarcoma, eczema Herpeticum ,herpes Oesophagitis ,
Bronchopnenmonia and hepatitis.
Herpes viruses infections

Hemophilus influenza :
Gram negative bacteria cause lower respiratory tract infection and meningitis . so there is pharyngitis sinusitis ,
laryngitis, otitis media . Bronchitis especially complicate viral respiratory tract infection obstruction of air ways by fibrin
rich exudate similar to Streptococcus Pneumonia infection. H. influenza also produce suppurative meningitis in children.
Tuberculosis :
Mycobacterium tuberculosis and M.bovis kill 3 million patient each year
M. tuberculosis transmitted by inhalation mainly, M.bovis is transmitted by milk as for M. avium and M.intracellurar
cause infecting in aids patients ,M. leprae is the cause of leprosy
Pathogenesis of T.B. depend on
1- Virulence of bacteria
2- Relationship of hypersensitivity to immunity
3- Infection degree
So T.B give no toxins ,no endotoxin and no histolytic enzymes but enter macrophages and cause delayed type of
hypersensitivity in which macrophages secrete TNF- which cause tissue damage and fever
DTH reaction cause destruction of tissue initially non specific reaction by mononuclear cells (lymphocytes
macrophages . plasma cells )and few neutrophils then by 2-3 weeks developed in to granuloma with caseous necrosis
at the center forming typical tubercle .the host response depend on either the primary infection (first exposure to T.B or
2nd exposure (previous infection ) the role of interferon gamma (INF-ɤ) secreted by sensitized lymphocytes (CD4+ ), and
activate the macrophages for phagocytic activity to kill T.B and cause tissue damage .
Bacterial infections

When inhaled T.B in to the lung phagocytosis by alveolar macrophages the T.B still
multiply and lyse macrophages and enter new cells which transport T.B to hilar lymph
nude during few weeks, the granuloma developed with central necrosis .
this under effect of (INF-ɤ) released by CD4+ cells and granuloma developed under effect
of (INF-ɤ) and TNF-α which cause activation of macrophages ,and later on tissue damage
.(caseation) followed by calcification in lung and hilar lymph node termed Ghon complex.
Secondary and disseminated T.B this occur when reinfection or reactivation of dormant
bacilli from primary infection when too much virulence of bacilli or patient susceptible to
infection (low immunity ) also disseminated T.B in blood circulation , lymphatic and cause
caseation and granuloma in kindly lungs , meninges, bone marrow and other organs.
The caseation may followed by cavitation and T.B reach blood circulation and cause
military T.B in various organs.
Primary T.B.

Pathological features :
1- Tuberculosis leprosy:
when high cellular immunity tuberculuid leprosy and epithelioid granuloma in skin localized
flat red in colour with induration ,depressed center , Nerve when affected lead to atrophy in
skin and muscles when trauma , this part were ulcerated ,contraction , microscopically,
epithelioid granuloma , giant cells. Lymphocytes (CD4, CD8) aggregation .
2- Lepromatous leprosy:
Involve skin , nerves ,eye, testes , hand ,feet no infection in vital organ brain.. because high
temp. more than in peripheral organs . the lesions began macules, papules or nodular lesion ,
coalese of lesion give a lion facies .in nerve lead to loss of sensation in feet ,hand.
Microscopically:
Macrophages laden with bacilli (AFB) some time in liver, lymph nude , spleen . in advanced
cases in testes cause destruction and erythema nudosum vasculitis .
• Lepromin test like T.B by injection of lepromin Ag M.leprae
Leprosy (Hansen disease):
Caused by M. leprae infect skin and peripheral nerve it transmitted through inhalation taken
by alveolar macrophage , through blood reach skin and peripheral organs.

Staph epidermidis :
cause opportunistic infection in catheterized patients, prosthetic valves , drug addicts
Staph aureus :
Causes : boil, carbuncles in skin, pharyngitis, pneumonia , endocarditis ,food poisoning, infections of burn,
surgical wound infections, toxic shock syndrome.
virulence factors include:
1- Protein surface protein help bacteria to attach to tissue
2- Lytic enzymes , proteases ,lipase
3- Toxins include hemolytic , leucocidin enterotoxin, hemolytic toxins ,exfoliation toxin associated with
scaled skin syndrome . toxic shock syndrome toxin .
Streptococcal infection :
Associated with pharyngitis , scarlet fever , erysipelas , impetigo (infection of superficial epidermis)
rheumatic fever, glomerulonephritis .
In mouth strept. Viridanse endocarditis
In mouth strept.Mutans dental caries
Strep. Faecalis (enterococcus faecalis) UTI and endocarditis
Strep. Agalactiae UTI ,neonatal sepsis, meningitis.
Pyogenic bacteria

Virulence :
1- M protein prevent phagocytosis
2- C5a peptidase (degrade C5a )
3- Surface molecules (protein ) to attach to host extracellular matrix
4- Polysaccharides inhibit phagocytosis
5- Pneumolysin activate classical pathway lysis target cells
6- Pyogenic exotoxin cause fever rash
7- Metabolism of sucrose in to lactic acid by streptmutans cause demineralization of tooth ,plaque,
caries formation
8- Anti Strept M protein antibodies cause cross react with cardiac myosin lead to rheumatic fever .
Gastrointestinal infection :
occurred when host detenses were weakend
1- Low gastric acidity.
2- Antibiotic.
3- Decrease peristalsis movement.
4- Mechanical obstruction.

Enteropathogenic bacteria cause disease by;
1- Production of enterotoxins it cause food poisoning e.g. : S. typhimurium
2- Exotoxin by E.coli , vibrio cholera cause intestinal damage , secrete too much water
3- Invasion of mucosal layer by shigelladysentria , salmonella cause hemorrhage ,ulceration
4- S- typhi cause damage mucosal layer to peyer,s patches and to blood stream causing
enteric fever.
Normal defense in GIT :
1- Acidic ph gastric juice.
2- Mucus layer covering the gut epith.
3- Pancreatic and bile salts lyse microbial agents .
4- IgA( Anti septic paint ) and M cells modified epith. Cover mucosal associate lymphoid tissue
take the pathogen to MAIT area to destroy bacteria.
5- Bacterial flora inhibit pathogens establishment.

Helicobacter pylori :
causes :
1) chronic superficial gastritis .
2)chronic atrophic gastritis .
3) carcinoma of the stomach, and sometimes lymphoma when reactive, invasion of B and
T cells clones.
Clostridial infection :
anaerobic bacteria produce the following disease :
1)Anaerobic cellulites and gas gangrene by Cl. perfringes (welchii)
2)Tetanus by Cl. tetani all these infection occurred by contaminated wound, the toxins of
these bacteria (neurotoxin) potent toxin cause skeletal muscle contraction .
3)Botulism caused by Cl. botulinum in contaminated canned food, also neurotoxin released
and block acetylcholine release so paralysis of muscles fibers occur .
4)Pseudo membranous colitis by Cl. difficile also release multiple toxins.

Caused by Treponema pallidum detected by :
1- silver stain .
2- dark filed examination .
3- immunofluorescence .
The infection occur in 3 stages :
Primary stage : occur within 3 weeks, the infection in the form of firm non tender red
raised lesion ( chancre ), located in external genitalia composed of plasma cells, macrophages
infiltrate, with obliterative endarteritis.
Secondary stage : occur within 2-10 weeks as a diffuse rash in palms and soles, with white
oral lesion, fever, arthritis, and lymphadenopathy.
Tertiary stage : occur later on in years after the primary the inflammatory lesions in
aorta, heart, CNS, liver, bone, skin, called gummas composed of granuloma with central
necrosis surrounded by macrophage palisading with fibroblasts and outer plasma cells.
Syphilis:

Genital syphilis :
the treponema transmitted from infected mother to placenta and cause :
1) late abortion
2) still birth
3)death of newborn
4)persist a latent in child life.
Gonorrhea:
caused by Neisseria gonorrhoeae, gram negative diplococcus their pathogenesis occur
when bacteria invade epithelial cells and facultative intracellular bacteria depends on host
cell actins filaments, their capsule inhibit phagocytosis, secrete protease cleave IgA and
release endotoxin which give TNF-∝ cause shock and multisystem failure.the infection by
this microbe begin purulent exudates, granulation tissue formation, fibrosis in urethra with
mucopurulent exudates and spread to epididymis, prostate, seminal vesicles and in chronic
cases sterility occur.

Obligate intracellular organisms in 2 forms either elementary bodies or
reticulate bodies both cause :
1-Lymphogranulomavenereum with epidermal vesicles on the genitalia then ulcerate and
oozes fluid, the ulcer base, granuloma formation with stellate obscesses in the center of
granuloma.
2-Inclusion conjunctivitis: in infants from mother with cervical infection caused by C.
trachomatis.
3-Reiter syndrome : a combination of conjunctivitis, genital infection and polyarthritis.
4-Trachoma : kerato conjunctivitis cause blindness in poor societies and transmitted by hand
contacts, flies.
5-Ornithosis :pneumonia by C. psittaci secreted from infected birds inhaled with dust particles.
Diagnosis; by fluorescent antibody reaction, culture on cell culture and by PCR.
Chlamydial infection

• schistosomiasis, bilharziasis :
caused S. mansoni, S. hematobium and S. japonicum. larvae penetrate skin, migrate by B. circulate to traverse the lung,
reaching pelvic or portal vein. in pelvis develop into adult with egg production and granuloma develop around the
egg in pelvis, bladder. Some eggs from portal vein to intestine wall depend on type of parasite with granuloma. (S.
mansoni) In pelvis. granuloma develop into carcinoma when in bladder occurred (S.hematobium), egg in stool or urine.
• S.mansoni in liver when present in portal vein cause :
1- Hepatotoxic effect by egg toxin
2- Granuloma in liver mediated by TNF, H1, H2, cells .
3- TH2 secret IL 3,4 stimulate mast cells level.
4- TH2 secrete IL5 important for eosinophils and give basic protein kill the larvae.
5- egg stimulate the lymphocyte to give fibroblasts growth factor to form fibrosis in portal area or in other site
.
Complication of schistosomiasis include :
1-granuloma in liver, gut, pelvis, in the center ova present, portal fibrosis pipe – stem fibrosis .
2-granulomatous pulmonary arteritis.
3-glomerulonephritis due to Ag- Ab complexes deposition.
* S.hematobium in urinary bladder cause hematuria, calcified granuloma, later on develop to carcinoma ( transitional
cell carcinoma ) or (squamous cell carcinoma ).
Parasitic infection :

Hydatid cyst :
caused by Echinococcusgranulosus and sometime Echinococcusmulticularis .
the hexacanth embryo (larvae) hatch in intestine of intermediate host ( taken
contaminated food with egg ). the larvae migrate to liver mainly and to the
lung and other organs cause hydatid cyst enlarged gradually and cause
space equipying lesion. the wall of cyst composed of germinal layer with
protosolices surrounded by laminated hyalinized layer and fibrous capsule
outside infiltrated with mononuclear cells, giant cells and easinophils.
Trichomoniasis :
sexually transmitted disease, protozoa flagellated, cause superficial infection
in genital tract of male and female with watery fluid in vagina and itching,
urethritis with mononuclear cells and neutrophils infiltration.

Aspergillosis :
associated with allergic lesions, sinusitis, pneumonia, the fungus appear branching filaments hyphae and budding
spores. The fungus surface had;
1) sialic acid to bind with protein matrix laminin, fibronectin.
2) produce a flatoxins (carcinogenic).
3) had restrictocin and mitogillin – both ribotoxin inhibit protein synthesis.
4)allergic reaction through IgE mediated hypersensitivity,allergicalveolitis and bronchopneumonia with asthma
mediated by mitogillin.
5) aspergilloma colonization of the pre-existing cavity caused by T.B ,bronchiectasia.
6) massive aspergillosis in immunodeficient individuals with infection of all organs.
•Candidiasis : associated with superficial infection of oral cavity (thrush), valvovaginitis or systemic infection
associated with Bronchopulmonary disease and oesophagitis. candidiasis caused by candida albicans .
•Sporotrichosis : caused by sporotrichiumschenkii ulceration with abscess formation in skin and subcutaneous
tissue.
•Disease of trichophytonrubrum include Tineacorporis (Ring worm) tineapedis ( Athlet's foot).
•Disease include histoplasmosis, Histoplasmacapsulatum and coccidiodomycosis ( Coccidiodesimmitis )
cryptococcusis (Cryptococcus neoformans ) both associated with pneumonia and meningitis.
MYCOTIC INFECTION

Lecture 9 the infectious disease

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