Fever - Definition, Types, Causes and Effects

The body temperature refers to the temperature of the viscera and tissues of the body. It is kept within the normal level by maintaining a balance between the heat gain and heat loss, which is regulated by the hypothalamus.

The body temperature is best recorded with a mercury thermometer which should be kept in position for about a minute. Usually temperature is recorded in the axilla. However, if there is a lot of perspiration, oral temperature should be taken. In cholera, rectal temperature is recorded which may be high, whereas the skin temperature may be subnormal.

The normal body temperature varies from 36 degree Celsius - 37.5 degree Celsius. There is normally a diurnal variation of 1 degree Celsius, the lowest temperature being between 2-4 am and highest in the afternoon.

Fever or pyrexia is an increase of more than 1 degree Celsius or any rise above the maximal normal temperature.

Types of Fever

1. Continuous fever: The temperature remains above normal throughout the day and does not fluctuate more than 1 degree Celsius in 24 hours e.g. lobar pneumonia, typhoid, urinary tract infection, infective endocarditis, brucellosis, typhus, etc.
2. Remittent fever: The temperature remains above normal throughout the day and fluctuates more than 2 degree Celsius in 24 hours e.g. typhoid, infective endocarditis, etc. This type of fever is most common in practice.
3. Intermittent fever: The temperature is present only for some hours in a day and remains to normal for the remaining hours. When the spike occurs daily, it is quotidian, when every alternate day, it tertian and when every third day, it is quartan. Intermittent fever is seen in malaria, kala-azar, pyemia, septicemia etc.
4. Hectic or septic: The temperature variation between peak and nadir is very large and exceeds 5 degree Celsius e.g. septicemia.
5. Pel Ebstein type: There is a regular alternation of recurrent bouts of fever and afebrile periods. The temperature may take 3 days to rise, remains high for 3 days and remits in 3 days, followed by apyrexia for 9 days.
6. Low grade fever: Temperature is present daily especially in the evening for several days but does not exceed 37.8 degree Celsius at any time. Usually it does not indicate disease, but it is commonly present with tuberculosis.

Causes of Fever

1. Infection: Bacterial, viral, rickettsial, fungal parasitic, etc.
2. Neoplasms: Fever may be present with any neoplasm but commonly with hypernephroma. Lymphoproliferative malignancies, carcinoma of pancreas, lung and bone and hepatoma.
3. Vascular: Acute myocardial infarction, pulmonary embolism. Pontine hemorrhage, etc.
4. Traumatic: Crush injury
5. Immunological:

• Collagen disease, SLE, rheumatoid arthritis.
• Drug fever
• Serum sickness

6. Endocrine: Thyrotoxicosis, Addison’s disease.

7. Metabolic: Gout, porphyria, acidosis, dehydration

8. Hematological: Acute hemolytic crisis

9. Physical agents: Heat stroke, radiation sickness.

10. Miscellaneous: Factitious fever, habitual hyperpyrexia, cyclic neutropenia

Special Types of Fever

1. Fever with rigors: This occurs in:

• Malaria
• Kala azar
• Filariasis
• Urinary tract infection
• Cholangitis
• Septicemia
• Infective endocarditis

2. Fever with herpes labialis: Elevated body temperature may activate the herpes simplex virus and cause small vesicles around the angle of the mouth (herpes labialis). It occurs with:

• Pneumonia
• Malaria
• Meningitis
• Streptococcal infection

3. Fever with rash: This is seen in:

• Chicken pox
• Small pox
• Measles
• Rubella
• Typhus
• Allergy

4. Fever with membrane in the throat: occurs in:

• Diphtheria
• Infectious mononucleosis
• Agranulocytosis
• Moniliasis
• Vincent’s angima

5. Fever with delirium: This is common in:

• Encephalitis
• Typhoid state
• Meningitis
• Pneumonia (especially in alcoholics and elderly people with senility)

6 Hyperpyrexia
Hyperpyrexia is said to occur when body temperature is more than 105 degree Fahrenheit.

1. Tetanus
2. Malaria
3. Septicemia
4. Heat Stroke
5. Encephalitis
6. Pontine hemorrhage

Benefits of Fever

In some human disease, fever is beneficial, e.g. widespread cancer, neurosyphilis, chronic arthritis, etc. Fever was often induced in these diseases by injection of milk protein or BCG vaccine.

It has been suggested that fever is associated with release of endogenous pyrogens, which activate the T cells and thus enhance the host defense mechanism.

Harmful Effects

1. Hypercatabolism-nitrogen wastage and weight loss.
2. Fluid and electrolyte imbalance-due to sweating.
3. Convulsions and brain damage
4. Circulatory overload, arrhythmia, etc.

What is Jaundice and When Does It Occur

Jaundice is a symptom complex which is characterized by yellow coloration of tissues and body fluids due to an increase in bile pigments i.e. Bilrubin and related products

It may arise due to:

• Increased bile pigment load to the liver.
• Affection of bilirubin diffusion into the liver cells.
• Defective conjugation.
• Defective excretion.

Other causes of yellow coloration of tissues

Yellow coloration of tissues can occur due to carotenemia and mepacrine therapy.

Bilirubin Metabolism

1. Breakdown phase: Hemoglobin released by breakdown of aged cells is broken down into globin and heme. The heme is further broken into iron and bilirubin. Bilirubin attaches to serum albumin and is transported to the liver where it is taken up.
2. Conjugation phase: In the liver, bilirubin is separated from albumin and conjugated to glucuronide by glucuronyl transferase. The conjugated bilirubin is water soluble and can be excreted by kidneys.
3. Alimentary phase: The conjugated bilirubin is excreted through the bile canaliculi and reaches the intestines where it is converted to stercobilinogen and urobilinogen by the intestinal bacteria. About 70% of this is absorbed in the colon and brought back to the liver and re-excreted (enterohepatic circulation). Unabsorbed stercobilinogen gives brown color to the faces.
4. Excretion phase: Circulating urobilinogen is carried to the kidneys for excretion in the urine as urobilinogen.

Normal values

Serum bilirubin: Total: 1 mg%; Direct: 0.25 mg%. Urinary bilirubin is present if direct bilirubin is greater than 0.4 mg% in serum.

Urine Urobilinogen: 100-200 mg/day.

Fecal stercobilinogen: 300 mg/day

Distribution of Jaundice

High concentration of bilirubin (hyperbilirubinemia), the bile product and its congeners are responsible for yellow discoloratrion of skin in jaundice. They bind with circulating proteins.

Bilirubin has more affinity for nervous tissue like basal ganglia and elastic tissues such as skin, sclera and blood vessels.

Infections:

• Viral hepatitis
• Weil’s disease (Leptospirosis)
• Septicemia
• Malaria
• Typhoid

Toxicity

• Anesthetic agents: Halothane, chloroform
• Anticoagulants: Phenindione
• Anti-tuberculous drugs: Rifampicin, P.A.S., I.N.H., Thiacetazone
• Metals: Arsenic, mercury, gold, bismuth
• Chemicals: DDT
• X-ray irradiations

Cirrhosis

• Portal Hypertension
• Biliary cirrhosis
• Hemochromatosis

Extra Hepatic Obstruction

• Stone
• Stricture
• Parasites
• Acute cholecystitis
• Carcinoma of the head of the pancreas
• Neoplasm of bile ducts, gall bladder and ampulla of Vater
• Congenital: Biliary atresia

Intra Hepatic Obstruction
1. Cholestatic phase of infective hepatitis
2. Drugs – Steroids, chlorpromazine, PAS, sulfonamides, chlorpropamide tolbutamide, methyl testosterone

Hemolytic Causes of Jaundice

There is an increased destruction of red blood cells which causes increase in production of bilirubin. This may occur due to

• Infections like Malaria, Clostridium welchi
• Drugs like L. Methyldopa, quinine, phenacetin, sulfonamides
• Burns
• Irradiation
• Poisons as in: Snake Venom, Favism
• Mismatched blood-tranfusion
• Paroxysmal Cold Hemoglobinuria
• Lymphoma
• Leukemia
• Systemic lupus erythematosis
• Uremia

Congenital Hyperbilirubinemia

• Gilbert’s syndrome
• Crigler-Najjar syndrome
• Dubin Johnson syndrome
• Rotor’s syndrome.

What Can Cause Diarrhea?

1. Osmotic Causes
   • Laxative abuse
   • Maldigestion of food
2. Infections
   • Typhoid
   • Cholera
   • Amebiasis
   • Giardiasis
   • Helminthiasis
3. Endocrine diseases
   • Thyrotoxicosis
   • Diabetes
   • Addison’s disease
4. Drugs
   • Thyroxine
   • Prostigmine
   • Ampicillin
   • Phenolphthalein
5. Anxiety:
   • Irritable bowel syndrome
6. Miscellaneous
   • Malignant carcinoid syndrome.

What Are Possible Causes of Weight Loss

Weight loss is a common sympom that occurs in many conditions. Most common of these are

Caloric malnutrition-Fasting, inappropriate diet

Chronic infections-Infective endocarditis, tuberculosis, amebic liver abscess, fungal infections, etc.

Acute infections-Viral hepatitis, typhoid, septicemia

Malignancy

Malabsorption syndrome

Endocrine Diseases

Diabetes mellitus, thyrotoxicosis, panhypopituitarism, Addison’s disease, etc.

Anorexia nervosa