Epidemiology

Epi means above, upon
demos means people
logy means knowledge
Definition:
     The study of distribution and determinants (risk factors) of health related states or events in a specified population and the application of this study is to control health problems is called as Epidemiology.
It involves:
a) Distribution of Disease
b) Disease Frequency
c) Determinants of Risk factors
Types of Epidemiology
Descriptive epidemiology:
     The study of distribution of diseases in the society is called as descriptive epidemiology.
Analytical Epidemiology:
The study of determinants of risk factors of disease is called as analytical epidemiology.
Explanation

Disease Frequency:

     Epidemiology is the measurement of frequencies of diseases such as disability and deaths and summarize this information in the form of rates and ratios e.g. Prevalence (number of existing cases) rate, Incidence (number of new cases) rate, Death rate, Morbidity (disease) rate etc.

Rate and Ratio is the basic measurements of epidemiology in the frequency of the diseases. These rates are essential for comparing disease frequencies in different population or sub groups of the same population.

Distribution of Diseases:
     An important function of the epidemiology is to study these distribution patterns in various subgroups of the population by time, place, person etc. i.e. epidemiologist examine whether there has been an increase or decrease of disease over time spin. Whether there is a high concentration of disease in one geographic area than in other. Whether the disease occur more often in age related factors such as male, female or children etc. Such type of study is called as descriptive study.
Determinants of Disease:
     A unique feature of epidemiology is to test etiological factors and identifying the underlying cause. This require the epidemiological  principles and methods. Such type of study is called analytical study. Such study helps in the causation of the underlying risk factors and develop preventive measures and preventive programs for the promoting of good health.
Difference between Epidemiological and Clinical medicine:

• Epidemiology is the unit study in a defined population whereas clinical medicine is a case study.
• In epidemiology, the epidemiologist is concerned with the disease in the entire population whereas in clinical medicine individual patient is treated.
• Epidemiologist deals with the sick people as well as healthy people whereas in clinical medicine the doctor deals with the sick people.
• Epidemiologist goes to population and examine the patients whereas in clinical medicine the patient comes to doctor for examination.

Finally it is concluded that epidemiology and clinical medicine are not antagonizing each other but both are closed related and co relevant with each other. Without epidemiologiist , doctor do nothing and vice versa.
Approach of epidemiology:
Asking question and comparison.
Asking question:
Some of the question are as follows.
What is the event?
What is its magnitude?
What did it happen?
When did it happen?
Who are affected?
Why did it happen?
Measurement in epidemiology
     The scope of measurement in epidemiology is very broad and give us specific values for the specific measurements. These measurements are the following.

• Measurement of Mortality (death rate)
• Measurement of Morbidity (disease cases)
• Measurement of Disability 
• Measurement of specific infant Mortality
• Measurement of presence, absence or distribution of the characteristics attribute of the disease
• Measurement of medical needs, health care facilities, utilization of health services and other related events

Tools of measurement

• Rate 
• Ratio
• Proportion

      Rate is the number of particular events in a population during a given period of time e.g. crude rate, specific rate, standard rate. Ratio is the comparison b/w the two or division of one quantity by another quantity e.g. the sex of children attending an immunization clinic male and female).
                                                                  n
      Ratio, proportion, rate =  x     × 10
                                                y                                                                                                                                                                                               n
Rate =  number of  cases or events occurring during a given timeperiod   ×10      
              population at risk during the same time period

Aims of epidemiology
     According to the international epidemiological association, epidemiologyhas the three main aims.

• To describe the destribution and magnitude of health and disease problems in human population.
• To identify the risk factors in pathogenesis of disease.
• To provide the data essential for planning, implementation and evaluation  of services for the prevention, control and treatment of disease.

     These are the general applications of epidemiology. According to WHO, the ultimate aims of epidemiology are:

• To eliminate or reduce the health problems and its consequences.
• To promote, protect and restore the health.

Read more »

History of Community Medicine

Origin of Community Medicine

• Primitive Medicine:

               The medicine which were used primarily by the Religious people etc.

• Indian Medicine:

               It includes Homopathic and Unites

• Egyptian Medicine:

               These medicine were more technical and advanced.

• Chinese drugs:

               They developed Immunization(Edward Jinner) for the first time.

• Roman Medicine:

               They develop the units of drugs.

• Greek Medicine:

               It involves the Medicine and health advancement.

• Birth of Community Medicine:

              Curative Medicine: The medicine used for curing the disease.
              Preventive Medicine (community medicine): The medicine used for prevention from diseases.

Read more »

Hypertension

Definition:

Sustained high blood pressure is known as hypertension.

Blood pressure is the pressure of the blood on the walls of the vessels.

Normal BP is 120/80 mmhg

In Hypertension BP > 130/90

         i.          Grade 1 hypertension: Also called Mild hypertension

Systolic BP = 130-140 mmhg          Diastolic BP = 85-90 mmhg

       ii.           Grade 2 hypertension: Also called Moderate hypertension

Systolic BP = 140-160 mmhg          Diastolic BP = 90-95 mmhg

      iii.           Grade 3 hypertension: Also called Severe hypertension

Systolic BP = 160-180 mmhg          Diastolic BP = 95-100 mmhg

     iv.            Grade 4 hypertension: Also called Malignant hypertension

Systolic BP >180mmhg          Diastolic BP > 110mmhg

Etiology:

Primary /Essential/ Ideopathic Hypertension:

In about 95% cases no cause of hypertension can be identified and the form of hypertensionis called primary or essential hypertension.

Secondary hypertension:

In about 5% cases, cause of hypertension can be discovered and the form of hypertension is called secondary hypertension.

Causes of secondary hypertension:

Ø  Renal and renovascular diseases:

o   Chronic renal failure

o   Glumerulonephritis

Ø  Endocrine disease:

o   Pheochromocytoma

o   Cushing’s syndrome

o   Conn’s syndrome

Ø  Drugs:

Oral contraceptive containing estrogens, NSAIDs and sympathomimetic agents

Ø  Alcohol consumption (chronic)

Ø  Coarctation of aorta ( localized narrowing of aorta)

Ø  Pregnancy

Read more »

Myocardial infarction (MI)

Definition:

The complete necrosis of the myocardium due to complete cessation (occlusion) of blood supply is called myocardial infarction.

Etiology:

·         Atherosclerotic plaque (unstable)

·         Embolic occlusion of coronaries

·         Severe and prolonged vasospasm

·         Drugs (Cocain and Amphetamine)

Clinical features:

Symptoms:

Ø  Chest pain

o   Severe and prolonged means more than 30 min not relieved with nitrates

o   Left side of chest and then radiates to left arm to left arm or back or neck

Ø  Vomiting

Ø  Sweating

Ø  Symptoms of heart failure in case of massive MI

o   Dizziness

o   Drowsiness

o   Severe shortness of breath

o   Unconsciousness (in some cases)

Signs:

§  Fist sign

§  Sweating/ diaphoresis

§  Vomiting

§  BP will be either increased or decreased

§  Pulse:

o   Tachycardia: Due to anxiety, low cardiac output or arrhythmias

o   Bradycardia: If there is inferior wall infarction

§  Chest (pericardium) examination:

Usually normal examination of the heart or having the following

o   Ventricular septal defect (VSD)

o   Pain systolic murmur (PSM)

o   A soft first heart sound

o   Fourth heart sound

o   Third heart sound reflects left ventricular dysfunction

§  Lungs:

Crepts at the bases of lungs

Investigation of MI:

ECG:

Ø  ST segment elevation

Ø  May be tachycardia or bradycardia

o   V3-V4 show anterior wall MI due to LAD involvement

o   II, III, aVF show inferior wall MI due to RCA involvement

o   I, aVL show high lateral wall MI due to circumflex

Cardiac enzymes:

Troponin T and I are raised up to 2 weeks while CK-MB remains elevated up to 3 days. Creatine kinase (CK) has three isoenzymes.

§  CK-MB: present in heart

§  CK-MM: present in skeletal muscle

§  CK-BB: present in brain

Echocardiography:

ü  It asses the myocardial movements i.e. whether Hypokinetic or Akinetic (no movement)

ü  It also asses the valves, whole function of the heart and aorta.

Routine investigation:

·         CBC (Complete Blood Count)

·         RBS (Random Blood Sugar)

·         Urea, creatinine

·         Serum electrolytes (especially K)

·         Cardiac X-ray

Treatment:

All the patients with suspected myocardial infarction should be confined to strict bed rest and admitted in hospital preferably in CCU.

General:

v  The aim of general treatment is to relieve the symptoms.

v  To relieve the pain, so strong analgesics especially opoid group (Morphine, codein) and anti-emetics (Gravinate) are used.

v  Complete bed rest for 24 hrs.

v  To treat other co-morbidities (diseases like HTN, DM)

Specific:

Antiplatelets:

Aspirin 300mg and clopidogril 300 mg are given as first (loading) dose then 75mg OD.

Thrombolytics:

§  Streptokinase

§  If once it is used then the patient become allergic to it

Beta blockers:

Atenolol, Propranolol, Metaprolol (cardio selective)

Nitrates:

Angised, isoket (nitroglycerine) should be given to relieve chest discomfort.

ACE inhibitors (Angiotensin Converting Enzymes):

They prevent or at least reduce the left ventricular dilatation and cardiac failure following myocardial infarction. These are Ramipril and Captopril (Tab. Capoten 25mg).

Read more »

Acute coronary syndrome (ACS)

Acute coronary syndrome includes unstable Angina and Non ST segment Elevation MI.

Angina:

Definition:

The clinical state in which a person have chest pain mostly on the left side with radiation to left arm and relieved within 30 minutes is called Angina.

Or

The clinical syndrome characterized by chest pain occurring as a result of decreased O2/ blood supply lasting within 30 minutes is called Angina.

Etiopathogenesis of Angina:

There is narrowing of the coronary arteries either by coronary vasospasm or by atherosclerosis (deposition of fats).

Types of Angina:

1.      Classical or exertional Angina:

It occurs due to increased myocardial oxygen during exertion or emotion in a patient of narrow coronary arteries. In such angina the typical pain is felt during exertion.

2.      Decubitus Angina:

This is angina that occurs when the patient lies down. It is the pain in chest during lying position usually present in case of cardiac failure.

3.      Prinzmetal’s or variant Angina:

This is angina that occurs at rest due to coronary vasospasm. The sympathetic overdrive (hyperactivity) causes the coronary vasospasm which leads episodic reduction of myocardial blood supply.

4.      Nocturnal Angina:

This is the angina that awakes the patient from sleep. It is chest pain at night during sleep especially because of vivid dreams.

5.      Unstable Angina:

This refers to angina of recent onset (less than one month), in which there is severe pain in chest last more than 10 to 15 minutes but less than 30 minutes and there is associated nausea/vomiting.

6.      Cardiac syndrome X:

There is a typical anginal pain with normal coronary arteries but there is some abnormality in the coronary microcirculation.

Risk factors of Angina:

·         Age: old age above 50 years

·         Sex: male> female above 50 years

·         Race: initially it was considered that rich people have greater chances of angina but now excluded

·         Hypertension (HTN): damaging the vessels

·         Diabetes Mellitus (DM): fat deposition

·         Smoking: damage the endothelium of the vessels

·         Obesity: hyperlipidemia

·         Family history: any angina in the family history

Clinical features of Angina:

Symptoms:

        i.            Chest pain:

Pain may arise on the following sites.

·         Left shoulder

·         Central chest

·         Throat

·         Epigastrium (if lower part of heart is involved)

·         Middle or lower of sternum

      ii.            Radiation of pain:

Pain can radiate to any dermatome from C8 to T4 including the following sites.

·         Left arm

·         Whole of chest (right chest)

·         Back of intrascapular region

·         Throat

   iii.            Weakness

    iv.            Nausea/ vomiting

       v.            Dyspnea:

Shortness of breath or abnormal awareness of respiration

Signs:

         i.            Fist sign: clenching of chest by fist

      ii.            Sweating

   iii.            Pale face

Investigations of Angina:

A.     ECG (ElectroCardioGraphy):

During pain:

Ø  ECG shows T wave inversion.

Ø  Elevation of ST segment in Prinzmetal’s angina

B.     ETT (Exercise Tolerance Test):

ü  Recording of ECG during exercise (on jogging machine)

ü  ST segment depression and T wave inversion

C.      ECHO cardiography:

·         It reveals the regional wall motion weakness.  

·         It asses the function of heart, valves and great vessels

D.     Cardiac enzymes:

Troponin I, troponin T and CK-MB are the enzymes normally present in the myocardium called cardiac enzymes. In case of MI they are increased in the blood but normal in Angina.

E.      Coronary angiography:

In this procedure, the coronary vessels are directly visualized in order to know the location and severity of coronary artery stenosis.

Management of Angina:

Treatment of Acute attack:

·         Nitrates:

Sublingual Nitrates (Angised) are given to relief the pain.

The MOA of nitrates is coronary and peripheral vasodilatation leading to decrease afterload and preload.

·         Ca channel blockers:

Amlopdipine (Norvasc 5mg) is used which block Ca channels leading to vasodilatation mainly arterial thus decreasing workload on the heart.

·         Analgesics:

Opoid analgesics (Morphine) along with (because of ‘vomiting’ side effect of opoid analgesics) antiemetic are used for the relief of pain.

Prevention of further attacks:

·         Anti platelets:

Aspirin and clopidogril (Noclot 75mg) are platelet-inhibiting agents preventing coronary thrombosis that is responsible for unstable angina and MI. The MOA is prevention of platelets adhesion with athero-sclerotic plaque and so the further stenosis or narrowing is prevented.

·         Nitrates:

Oral nitrates like Cardnit tablets are given to the patient.

·         Beta blockers:

Atenolol, propranolol, bisoprolol or metaprolol is used to reduce the myocardial oxygen demand by reducing the heart rate, force of cardiac contraction and therefore decreasing the cardiac output.

·         Lipid lowering drugs:

Rosuvastatin (Rast) or Atorvastatin (Ator) is used to lower the lipid level in the blood and thus preventing the further narrowing of the vessel.

Revascularization:

Indication of revascularization in the form of either Angioplasty (PTCA) or Bypass (CABG) is in Refractory Angina when the patient with unacceptable symptoms despite of maximum tolerable medical therapy or patient with left main coronary artery stenosis >50% with or without symptoms.

A.      Percutaneous Transluminal Coronary Angioplasty (PTCA): by the cardiologist

PTCA is performed by passing a fine guide-wire with deflated balloon through femoral artery, moved up to the diseased coronary artery. The balloon is then positioned across the stenotic area and inflated under pressure causing the dilatation of lumen. Now metallic stent is inserted that significantly reduces the chances of restenosis.

B.      Coronary Artery Bypass Grafting (CABG): by the surgeon

It is a major surgical method in which narrowed segments of coronary artery are bypasses using either free grafts of saphenous vein or the patient’s internal mammary artery (long thoracic artery). Radial artery graft is also commonly used now. Graft is sutured between aorta and coronary arteries distal to the obstruction.

Read more »

WHO (World Health Organization) 1948

Objectives:

ü  To strengthen the health services

ü  To promote standards of education, training and health related professions

ü  To provide information, assistance and counsel in health fields

ü  To promote nutrition, housing sanitation, and other aspects of environmental health

ü  To promote and conduct research

Read more »

Basic terms of Community Medicine

Infection:

The process of entry of microorganisms into human followed by their multiplication and development within the human body is called infection.

Example: colonization of staphylococcus aureus in the nasopharynx and skin.

Infestation:

It is the state of having parasite in or on the body which includes arthropods or animal parasites.

For person or animal the lodgment, development and reproduction of some organisms on the surface of the body or on the clothes

Host:

The lodgment to an infectious agent under natural conditions is called host. The place in which the parasite attains maturity and passes sexual stages is called primary host or definitive host.

Contagious disease:

A disease that is transmitted through contact is called contagious disease.

Example: Scabies, STD, leprosy etc

Communicable disease:

Any illness due to specific infectious agent or its toxic products capable of being directly or indirectly transmitted from man to man, animal to animal or from the environment to man or animal is called communicable disease.

Epidemic:

Any disease, injury or health related events occurring suddenly in members clearly in excess of normal expectancy. It is increased level of diseases in a specific area and population is called as epidemic.

Endemic:

The constant presence of a disease or infectious agent within a given geographic area or population group is called endemic. It is the number of constant disease people in the specific area.

Pandemic:

An epidemic usually affecting a large proportion of the population and occurring over a wide geographic area such as a section of nation, the entire nation, a continent or the world is called pandemic. In short the disease in the vast geographic area is termed as pandemic.

Sporadic:

The cases occur irregularly, haphazardly time to time to time and generally infrequently, showing a little or no connection with each other, nor a recognizable common source of infection. The disease in the scattered area of the country is called sporadic e.g. polio, tetanus etc

Exotic:

Diseases which are imported to the country are called exotic. These are diseases which are not present in that area but came from outside e.g. Rabies in UK

Zoonosis:

An infection or infectious disease transmissible under natural conditions from vertebrate animals to man is called zoonosis e.g. rabies, anthrax, brucellosis etc

 Epizoonosis (epizootic):

An outbreak (epidemic) of disease in animal population is called epizootic e.g. influenza etc

Epornthetic:

Outbreak of disease in birds is called Epornthetic e.g. bird flu

Nosocomial infection:

It is hospital acquired infection originating in a patient while in a hospital denoting a new disorder is called nosocomial infection e.g. scabies, surgical wounds, hepatitis B, UTI etc

Opportunistic infection:

This is infection by an organism that takes the opportunity provided by low resistance or immunity to infect the and hence cause disease e.g. AIDS by HIV

Iatrogenic disease:

These diseases are caused by the negligence of physicians or other health professionals.

Read more »