Parasitic
1. Leishmania produce 3 kinds of disease in man

- visceral leishmaniasis (kala azar) due to Leishmania donovani complex, 
- cutaneous leishmaniasis due to Leishmania tropica complex, and 
- mucocutaneous leishmaniasis due to Leishmania braziliensis. 
 
 - cutaneous (Oriental sore) and mucocutansous leishmaniasis limit themselves to the skinalone (ulcers) in the former disease and skin plus mucous membranes in the latter variant. 

 - the diagnosis of cutaneous or mucocutaneous leishmaniasis is made by biopsy, culture, skin test, or serologic tests
 
 - the laboratory diagnosis of visceral leishmaniasis is made by performing a bone marrow aspirate and finding the leishmanial forms in macrophages, by culture, by hamster inoculation, or by serology. 
 - recovery from the cutaneous form incurs immunity.
 - treatment: stibogluconate 

THROMBOPHLEBITIS AND  PHLEBOTHROMBOSIS 
- The deep leg veins account for more than 90% of cases (DVT) 
- the most important clinical predispositions are: congestive heart failure, neoplasia, pregnancy, obesity, the postoperative state, and prolonged bed rest or immobilization 
- local manifestations: distal edema, cyanosis, superficial vein dilation, heat, tenderness, redness, swelling, and pain 
- migratory thrombophlebitis (Trousseau sign): hypercoagulability occurs as a paraneoplastic syndrome related to tumor elaboration of procoagulant factors 

Str. agalactiae

β-hemolytic, with its capsule being the major virulence factor.  Capsule inhibits phagocytosis and complement activation.  The CAMP factor (a hemolysin) is another virulence factor.

Group B strep are normally found in GI tracts and vaginas. 

Major disease is neonatal sepsis/meningitis after passage through infected birth canal.  May lead to meningitis, and CNS damage is high.  Mothers colonized with Group B strep should be treated pre-delivery.

Infectious Mononucleosis

It is an Epstein Barr virus infection in children and young adults.

Features

-Constitutional symptoms.
-Sore throat.
-Lymphnode enlargement.
-Skin rashes
-Jaundice.
-Rarely pneumonia, meningitis and encephalitis.

Blood Picture

- Total count of I0,000. 20,000 /cu.mm.
- Lymphocytosis (50-90%) with atypical forms. They are larger with more cytoplasm which may be vacuolated or basophilic. Nucleus may be indented. with nucleoli (Downy type I to III).
- Platelets may be reduced.
- Paul Bunell test (for heterophil antibody against sheep RBC) is positive
 

FUNGAL INFECTION

Aspergillosis

Opportunistic infections caused by Aspergillus sp and inhaled as mold conidia, leading to hyphal growth and invasion of blood vessels, hemorrhagic necrosis, infarction, and potential dissemination to other sites in susceptible patients.

Symptoms and Signs: Noninvasive or, rarely, minimally locally invasive colonization of preexisting cavitary pulmonary lesions also may occur in the form of fungus ball (aspergilloma) formation or chronic progressive aspergillosis.

Primary superficial invasive aspergillosis is uncommon but may occur in burns, beneath occlusive dressings, after corneal trauma (keratitis), or in the sinuses, nose, or ear canal.

Invasive pulmonary aspergillosis usually extends rapidly, causing progressive, ultimately fatal respiratory failure unless treated promptly and aggressively. A. fumigatus is the most common causative species.

 Extrapulmonary disseminated aspergillosis may involve the liver, kidneys, brain, or other tissues and is usually fatal. Primary invasive aspergillosis may also begin as an invasive sinusitis, usually caused by A. flavus, presenting as fever with rhinitis and headache

Immunoglobulins. (Ig)

 These are made up of polypeptide chains. Each molecule is constituted by two heavy and two light chains, linked by disulfide (S-S) bonds. The h~ chains are of 5 types, with corresponding, types or  immunoglobulin. IgG (gamma), IgM (mu µ ), IgA(alpha α), IgD(delta ), IgE(epsilon)

Each of these can have light chains of either kappa (k) or lambda type.Each chain has a constant portion (constant for the subtype) land a variable portion (antigen specific).

Enzyme digestion can split the Ig molecule into.2 Fab (antibody binding) fragments and one Fc (crystallisable, complement binding ) fragment.

Characteristics of Immunoglobulin subclasses

I. Ig G:

(i) Predominant portion (80%) of Ig.

(ii) Molecular weight 150, 000

(iii) Sedimentation coefficient of 7S.

(iv) Crosses placental barrier and to extra cellular fluid.

• (v) Mostly neutralising effect. May be complement fixing.

(vi) Half life of 23 days.

2.IgM :

(i) Pentamer of Ig.

(ii) Molecular weight 900, 000

(iii) 19S.

(iv) More effective complement fixation and cells lysis

(v) Earliest to be produced in infections.

(vi) Does not cross placental barrier.

(vii) Halflife of 5 days.

3. Ig A :

• Secretory  antibody. Found in intestinal, respiratory secretions tears, saliva and urine also.
• Secreted  usually as a dinner with secretory piece.
• Mol. weight variable (160,000+)
• 7 S to 14 S.
• Half life of 6 days.

4.Ig D :

• Found in traces.
• 7 S.
• Does not cross placenta.

5. Ig E

• Normally not traceable
• 7-8 S (MoL weight 200,000)
• Cytophilic antibody, responsible for some hypersensitivity states,