Smallpox (variola)
 - vesicles are well synchronized (same stage of development) and cover the skin and mucous membranes.
 - vesicles rupture and leave pock marks with permanent scarring.

Summary 
Hepatitis A → ssRNA → Picornavirus → Oral–anal
Hepatitis B → dsDNA → Hepadnavirus → Sexual contact , Blood (needles), Perinatal
Hepatitis C → ssRNA → Flavivirus → Sexual contact , Blood (needles)
Hepatitis D → ssRNA → Deltavirus → Sexual contact, Blood (needles)
Hepatitis E → ssRNA → Calicivirus → Oral–anal 

Cardiac arrhythmia

Cardiac arrhythmia is a group of conditions in which muscle contraction of the heart is irregular for any reason.

Tachycardia :A rhythm of the heart at a rate of more than 100 beats/minute , palpitation present
Causes : stress, caffeine, alcohol, hyperthyroidism or drugs

Bradycardia : slow rhythm of the heart at a rate less than 60 beats/min 

Atrial Arrhythmias 

- Atrial fibrillation

Atrial Dysrhythmias 

- Premature atrial contraction
- Atrial flutter
- Supraventricular tachycardia
- Sick sinus syndrome

Ventricular Arrhythmias 

- Ventricular fibrillation

Ventricular Dysrhythmias 

- Premature ventricular contraction
- Pulseless electrical activity
- Ventricular tachycardia
- Asystole

Heart Blocks 

- First degree heart block
- Second degree heart block 
o    Type 1 Second degree heart block a.k.a. Mobitz I or Wenckebach
o    Type 2 Second degree heart block a.k.a. Mobitz II
- Third degree heart block a.k.a. complete heart block

Atrial fibrillation

Atrial fibrillation  is a cardiac arrhythmia (an abnormality of heart rate or rhythm) originating in the atria.
AF is the most common cardiac arrhythmia

Signs and symptoms

Rapid and irregular heart rates
palpitations, exercise intolerance, and occasionally produce angina and congestive symptoms of shortness of breath or edema
Paroxysmal atrial fibrillation is the episodic occurence of the arrhythmia  Episodes may occur with sleep or with exercise

Diagnosis: 

Electrocardiogram
- absence of P waves
- unorganized electrical activity in their place
- irregularity of R-R interval due to irregular conduction of impulses to the ventricles

Causes:

- Arterial hypertension
- Mitral valve disease (e.g. due to rheumatic heart disease or mitral valve prolapse)
- Heart surgery
- Coronary heart disease
- Excessive alcohol consumption ("binge drinking" or "holiday heart")
- Hyperthyroidism
- Hyperstimulation of the vagus nerve, usually by having large meals

Treatment

Rate control by 
Beta blockers (e.g. metoprolol)
Digoxin
Calcium channel blockers (e.g. verapamil)

Rhythm control

Electrical cardioverion by application of a DC electrical shock
Chemical cardioversion is performed with drugs eg amiodarone

Radiofrequency ablation : uses radiofrequency energy to destroy abnormal electrical pathways in heart tissue It is used in recurrent AF

In confirmed AF, anticoagulant treatment is a crucial way to prevent stroke

Atrial flutter

Atrial flutter is a regular, rhythmic tachycardia originating in the atria. The rate in the atria is over 220 beats/minute, and typically about 300 beats/minute

he morphology on the surface EKG is typically a sawtooth pattern.

The ventricles do not beat as fast as the atria in atrial flutter

Supraventricular tachycardia

apid rhythm of the heart in which the origin of the electrical signal is either the atria or the AV node
it is important to determine whether a wide-complex tachycardia is an SVT or a ventricular tachycardia, since they are treated differently

Sick sinus syndrome : a group of abnormal heartbeats (arrhythmias) presumably caused by a malfunction of the sinus node, the heart's "natural" pacemaker.

Ventricular fibrillation

is a cardiac condition which consists of a lack of coordination of the contraction of the muscle tissue of the large chambers of the heart. The ventricular muscle twitches randomly, rather than contracting in unison, and so the ventricles fail to pump blood into the arteries and into systemic circulation.

Ventricular fibrillation is a medical emergency: if the arrhythmia continues for more than a few seconds, blood circulation will cease, as evidenced by lack of pulse, blood pressure and respiration, and death will occur. Ventricular fibrillation is a cause of cardiac arrest and sudden cardiac death
 

Congestive heart failure (CHF)
A. Left-sided CHF

1. May result from nearly any heart disease affecting the left ventricle (e.g., ischemic heart disease, hypertension, valvular disease).
2. Common signs and symptoms include:
a. Dyspnea (shortness of breath) exacerbated by exertion.
b. Paroxysmal nocturnal dyspnea.
c. Orthopnea.
d. Tachypnea.
e. Pleural effusion.
f. Consequences include pulmonary edema.

B. Right-sided CHF

1. The most common cause of right heart failure is left heart failure. It uncommonly occurs in isolation. Other causes include left-sided lesions (mitral stenosis), pulmonary hypertension, cardiomyopathy, and tricuspid or pulmonary valvular disease.
2. Frequently presents with peripheral edema, especially in the ankles and feet (i.e., dependent edema), enlarged liver or spleen, and distention of the neck veins.

SHOCK

Definition. It is a clinical state of acute inadequacy of perfusion to tissues due to fall in effective circulating blood volume.

This inadequacy can be caused by :

• Increased vascular capacity
• Decreased blood volume
• Altered distribution of available blood
• Defective pumping system

Causes:

(1) Hypovolemic

• Massive hamorrhage (external or  internal).
• Loss of plasma as in bums.
• Dehydration due to severe vomiting, diarrhea  diabetic coma.
• Generalized capillary permeability as in anaphylaxis.

 (2) Cardiogenic

• Myocardial infarction.
• Pulmonary embolism.
• Cardiac tamponade

(3) Peripheral pooling:

• Endotoxic shock.
• Disseminated intravascular coagulation (DIC).

(4) Neurogenic:

• Syncope.
• Contributory factor in trauma, bums etc.

Metabolic changes in shock

• Hyperglycaemia due to glycogenolysis.
• Increased blood lactate and pyruvate due to anaerobic glycolysis. This results in metabolic acidosis.
• Protein catabolism and increased  blood urea.
• Interference with enzyme systems.

 Organs involved in shock

(1) Kidneys:

• Renal tubular necrosis.
• Cortical necrosis.

(2) Lungs:

• Oedema, congestion and haemorrhage.
• Microthrombi.

(3) G.I.T. :

• Mucosal oedema.
• Ulceration and haemorrhage

(4) Degeneration and focal necrosis in:

• Heart.
• Liver.
• Adrenals

(5) Anoxic encephalopathy

PERTUSSIS (Whooping Cough)

An acute, highly communicable bacterial disease caused by Bordetella pertussis and characterized by a paroxysmal or spasmodic cough that usually ends in a prolonged, high-pitched, crowing inspiration (the whoop).

Transmission is by aspiration of B. pertussis

Symptoms and Signs

The incubation period averages 7 to 14 days (maximum, 3 wk). B. pertussis invades the mucosa of the nasopharynx, trachea, bronchi, and bronchioles, increasing the secretion of mucus, which is initially thin and later viscid and tenacious. The uncomplicated disease lasts about 6 to 10 wk and consists of three stages: catarrhal, paroxysmal, and convalescent.