Bacterial diseases

Bacterial diseases

Venereal Diseases (V.D.)/Sexually Transmitted Diseases (S.T.D.)

1. Gonorrhoea. It is a venereal bacterial disease (Neisseria gonorrhoeae) which is spread through sexual contact, common toilets and under clothes. Some 150 million persons suffer from the disease worldwide. Incubation period is 2-5 days. The bacterium lives in genital tubes, produces pus-containing discharge, pain around genitalia and burning sensation during urination. It may lead to arthritis and eye infection (gonococcal ophthalmia) in children of gonorrhoea afflicted mothers. Disease can be cured through use of appropriate antibiotics e.g., Penicillin, Ampicillin.

2. Syphilis. It is highly infectious venereal bacterial disease (spirochaete Treponema pallidum) with incubation period of 3-5 weeks. Some 50 million persons suffer from the disease worldwide, Transmission is through sexual contact and from mother to children. In the first stage there is indurated infectious and painless ulcer or chancre on the genitals and swelling of local lymph glands, In the second stage, chancre is healed and there are skin lesions, rashes, hair loss, swollen joints and flu-like illness occasionally. In the tertiary stage chronic ulcers (gummata) appear on palate, nose and lower leg. There can be paralysis, brain damage, blindness, heart trouble and aortic impairment. The disease is curable through appropriate antibiotics, e.g., Pencillin, Tetracycline.

   A number of other sexually transmitted diseases are known. They include

   (a) Genital Herpes. Caused by Herpes simplex virus 2.
   (b) Genital Warts (Condyloma Acuminatum). Caused by Human Papilloma Virus.
   (c) Chlamydia. Caused by Chlamydia trachomatis.
   (d) Chancroid. By Gram (-) bacterium Haemophilus ducreyi.
   (e)Trichomoniasis. By flagellate protozoan called Trichomonas vaginalis.

Viral Diarrhoea or Gastroenterltis

1. Rotaviruses. They cause gastroenteritis with acute watery diarrhoea in infants and children.
Vomiting and fever also occur. Vaccine and drugs are unavailable. Mother's milk gives some protection through a glycoprotein (lactadherin) that binds to rotavirus (Newberg, 1997). Deaths occur due to dehydration.

2. Norwalk Viruses. The viruses cause gastroenteritis in all age groups, accounting for one third of all cases. Infection occurs through faecal contamination of food. It results in diarrhoea, nausea,vomiting and abdominal pain.

Bacterial Diarrhoea

1. Salmonellosis. It is caused by salmonella enteridis and S. typhimurium. The bacterium often contaminates meat and other proteinaceous food articles. The pathogen causes diarrhoea, vomiting, nausea, headache and paratyphoid fever. Antibiotics are helpful in curing. Oral or intravenous rehydration is required. Salmonellosis is more common in summer and early fall. Source is faecal contamination.

2. Shigellosis. It is due to bacterium Shigella shigae, S. flexneri and other species. The disease spreads through contaminated food. Shigellosis is characterised by frequent passage of stool with mucus, blood and abdominal cramps. Effective antibiotics are available. Oral or intravenous rehydration is required.
3. Campylobacter Gastroenteritis. It is caused by Campylobacter coli and C. jejuni. Transmission occurs through food and faeces. The gastroenteritis is characterised by abdominal pain, diarrhoea for 2-4 days and fever. Erythromycin is effective. Rehydration is required.

Diphtheria

It is an acute infectious disease produced by Gram (+) rod-shaped bacterium Corynebacterium diphtheriae. Diphtheria has three forms-gravis, intermedius and mitis. Infection occurs mostly in children of 2-5. Years. It spreads through droplet method by kissing, coughing, sneezing and contaminated articles. Incubation period is 1/2-5 days. Portal of entry is upper respiratory tract though implantation may occur anywhere. Exotoxin produced by pathogen causes epithelial necrosis of nose (nasal diphtheria), throat tonsils (pharyngeal diphtheria) and laryngotrachea (layngotracheal diphtheria). In the beginning there is mild fever, sore throat, mild headache and lassitude. Later on semisolid material oozes out of infected region where a grey false tough membrane may develop choking air passage. An offensive odour is produced. Toxaemia may reach heart, nervous system and kidneys resulting in their defunctioning. Antitoxin given within 12 hrs may give relief. Antibiotics (e.g., penicillin, erythromycin) may also provide some relief. Membrane has to be removed surgically. Schick test can indicate susceptibility. Triple vaccine, DPT, is useful.

ORS

It is oral rehydration solution used for correcting dehydration caused by diarrhoea in all age
groups. One litre of ORS contains 1.5 gm glucose, 3·5 gm NaCl, 2·9 gm KCI and 2·9 gm trisodium
citrate.

Cholera

It is a highly communicable bacterial disease caused by vibrio cholerae (= V. commae) which is
transmitted through contaminated food, water, drinks (formite transmission) and direct as vomits and stool of patient contain innumerable pathogens. Houseflies spread the pathogens. Floods, fairs, ware, and other calamities often lead to epidemic outbreak. Incubation period is a few hours to five days. There is acute diarrhoea with rice water stool (upto 40 per day), vomiting, muscular cramps, anuria and rapid dehydration. Oral rehydration (oral intake of sweetened and salted rice water or electrolyte
solution), intravenous rehydration and antibiotics (e.g., chloramphenicol, tetracycline) can treat the disease. Vaccination gives immunity for a few months. It is useful during fairs. Chlorination (by chlorogen or tropical chloride of lime/TCL) or ozone treatment of water, boiled water, disinfected food and antifly measures are essential for prevention. If untreated, the disease leads to collapse marked by sunken eyes, hollow cheeks, bluish colour, subnormal temperature, washerman's hands and feet, shallow quick breathing which may lead to death or slow recovery.

Pneumonia

Pneumonia is an inflammatatory disease of lungs with an incubation period of 1-3 days and characterised by accumulation of mucus/fluid in alveoli and bronchioles so that breathing becomes difficult. It occurs in all age groups and is major cause of death in young, old and chronically ill patients. Pneumonia is of several types. Common pneumonia is caused by Gram positive nonmotile paired bacterium called Streptococcus or Diplococcus pneumoniae and flu bacterium Haemophilus influenzae. The dieease is of two types-bronchopneumonia (young children, elderly persons) and lobar pneumonia (10-50 years). The disease is transmitted through droplets (sputum), aerosol of infected person, sharing utensils and other articles used by the patient. There is sudden chill, chest pain, cough with rusty mucoid sputum, rise in temperature and rapid shallow breathing. Abdominal distension and headache are also common. Useful drugs are erythromycin, tetracycline and sulphonamide. If untreated pneumonia leads to death.
Another acute infectious pulmonary disease is primary atypical pneumonia. It is caused by several types of pathogens like Mycoplasma pneumoniae, Chlamydia, Rickettsia, Parainfluenza virus, etc.

Plague/Bubonic Plague

Plague is due to rod shaped non-motile bacterium called Pasteurella/Yersinea pestis. It is primarily a disease of rats which is spread by rat flea (Xenopsylla cheopis). The disease kills the rats. Rat fleas leave the dead rats and attack humans. Death of rats is an indication of outbreak of plague. Plague is of three types. (I) Bubonic Plague. Incubation period is 2-6 days. Pathogen multiplies in lymph nodes, especially of armpit and groin which swell up into painful buboes. Other symptoms are high fever, chill, delirium, exhaustion and haemorrhages which turn black. The patient dies thereafter. Hence, plague is also called black death. It used to cause large scale deaths. For example, plague of 1348 killed over 60% of the europeans. Plague reached India for the first time in 1895 from Hong Kong. (II) Septicemic plague. Buboes do not occur. It is characterised by sepsis, severe headache, rapid pulse, fever, chill, nausea, vomiting and delirium leading to death within two days. (iii) Pneumatic/Pneumonic plague. It spreads from human to human (without rat flea) through droplets and fomites (soiled articles). It infects lungs causing pulmonary oedema, fever, anoxia, delirium and death within 24 hours. Streptomycin injection/oral tetracycline is effective drug. Plague occurred recently in Mamla village in Beed (Maharashtra) in 1993, from where it spread to Surat in Gujarat in pneumatic form. Anti-plague vaccine, spray of insecticides, killing of rats, nose caps and high cots (rat flea can jump upto 45 cm) are some preventive measures.

Peptic Ulcers

They are eroded areas in the lining of stomach and duodenum believed to be caused by excessive secretion of acid in gastric juice. Worry, stress, smoking, drinking and aspirin tend to increase the incidence. However, non-acid producing regions also develop gastritis and ulcers. It is now believed that ulcers are due to attack of Helicobacter pylori. It is passed on through food and faeces. Amoxicillin and bismuth subsalicylate are effective with chances of recurrence being common.

Pertussis/Whooping Cough

It is an infectious Gram negative nonmotile coccus bacterial disease (Bacillus = Bordetella = Haemophilus pertussis) of children which is characterised by attack of irritating cough accompanied by inspiratory whoop/gasp. The disease spreads through direct contact and droplet method. Incubation period is 10-15 days. There is inflammation of respiratory passage, cold, cough and mild fever in beginning, leading to accumulation of mucus and inspiratory whoop. Other symptoms are vomiting, cyanosis and haemorrhage of nose, eyes, brain, etc. Ieading to death. Convulsions and pneumonia may occur. Antibiotics eryhromycin, chloramphenicol, ampicillin and streptomycin are effective. Vaccination is available in form of DPT (diphtheria, pertussis, tetanus) for thrice inoculation to infants at monthly intervals.

Leprosy (Hansen's Disease ; Hansen, 1873)

Leprosy is contagious chronic bacterial disease (Mcobacterium leprae) of warmer climates as in
India and parts of Africa. Out of some 10.7 million leprosy patients, 3 million occur in India. The disease does not occur in children separated from patients in their infancy. It is because the disease is contracted on prolonged closer contact through skin lesions, nasal and throat discharges. Incubation period is 2-5 years, The bacterium can enter and damage nerves, skin, lymph nodes, eye, nose, mouth, muscles, spleen, etc. Infection begins with appearance of hypopigmented skin patches with little sensation thickening of peripheral nerves, numbness in some body parts, pain in some others, unexplained fever, finally appearance of ulcers, nodules, lesions, scaly scabs, followed by deformities in fingers, toes and wasting of body parts. Lepromata (singular leproma) are granulomatous cutaneous eruptions of leprosy. Presence of lepromin in skin tests can indicate appearance of leprosy. Surgery along with multidrug treatment (diaminodiphenyl sulphone or dapsone, rifampicin, clofazimine, ofloxacin,
alepol chaulmoogra oil) can cure the disease. However, the disease carries a social stigma.
National Leproey Control Programme (NLCP) is in progress in India. A vaccine has also been developed (Talwar, 1994).

Tuberculosis/TB

It is a bacterial (rod-shaped Gram +ve Mycobacterium tuberculosis; Koch, 1882) disease where the pathogen destroys the infected tissue and releases toxin called tuberculin (test called Mantoux reaction is tuberculin specific). Tuberculosis is of two types, pulmonary tuberculosis and extra pulmonary-tuberculosis. Pulmonary or lung tuberculosis is more common but other forms (intestinal, bone, skin, meningitis) also occur in appreciable number. Milk is a source of bovine tuberculosis,
Disease is spread by direct contact and droplet method. Incubation period is from a few days to several
months. The symptoms include evening-night fever, night sweating, loss of weight, cough, difficult breathing and haemoptysis (blood in sputum) in case of pulmonary TB while there is acute pain in other cases. Meningitis leads to coma. Sputum, tuberculin, X-ray and gastric analysis are carried out to diagnose disease. Antituberculosis drugs are streptomycin, isoniazid, thiacetazone, PAS (para-amino
salicylic acid), ethambutol, pyrazinamide, kanamycin, rifampin, etc. Treatment takes 8-9 months. It cannot be stopped mid way as the parasite tends to develop resistance to the drugs. Surgery is required for removing infected lump. Vaccination with BCG (Bacillus Calmette Guerin) provides immunity. lt was obtained from bovine bacillus by Calmette and Guerin in 1921. Mycobaeterium uaccae, a soil bacterium, has been found to combat tuberculosis (Stanford et al, 1997).

Typhoid

It is an acute infectious disease caused by Gram(-) anaerobic flagellate bacillus called Salmonella typhi. Typhoid spreads through food, milk and water contaminated with intestinal discharges and urine either directly or through flies and faulty personal hygiene. Some 2.5 million persons suffer from it annually. Certain humans function as carriers without suffering from it. Mary Mallon, popularly called typhoid Mary was one such carrier. She was a cook who continued to spread the diseases for several years through her food preparations
         The pathogenecity of bacterium is due to two antigens, O-antigen of liposaccharide outer membrane and H-antigen present over flagella. After reaching intestine, the bacteria enter intestinal wall and multiply inside macrophages in mesentric lymph nodes. After multiplication, they are released in blood stream to be passed into liver, gall bladder, spleen, bone marrow, lungs, kidneys, etc, for further multiplication. After multiplication the bacteria are released and reach the intestinal wall where they
produce typhoid ulcers. Incubation period is 1-3 weeks. Toxin released by lysed bacteria in blood causes high fever in steps. There is pea soup diarrhoea which may become haemorrhagic. A rose coloured rash may occur on upper abdomen at the end of first week. Untreated typhoid passes through 4 stages, each lasting about a week. Unless treated a member of complications begin to develop in third week including intestinal perforations, anaemia, arthritis, nephritis, bronchitis, meningitis, myocarditis, cholecystisis.
       Lately, resistant typhoid has appeared. Vaccine (oral and injectible alone or along TAB) provides immunity for 1-3 years. Antibiotics are available. They are ampicillin and chloramphenicol. Resistant cases are treated with quinoline derivative (e.g., Ciprofloxacin, Ofloxacin). Treatment should be prolonged as the patient may continue to pass bacteria for weeks even after recovery. Surgical removal of gall bladder (cholecystectomy) is sometimes carried out in order to remove source of infection. Typhoid isdiagnosed by Widal test.

Tetanus/Lock Jaw (Dhanustamba)

It is an incurable bacterial disease (Clostridium tetani) characterised by painful muscular contraction of jaw. The incidence of its occurrence is quite common in India with high mortality in infants and mothers. The bacterium occurs in intestine of horse and other animals from where they pass out as spores (viability 60 yrs) in their excreta that mixes in street dust and contaminates various articles including rusted iron. Wounds and cuts, surgical instruments coming in contact with road dust may cause entry of spores into body. The bacteria are released inside the body. They multiply and begin to secrete a toxin named tetanospasmin. Incubation period is 3-28 days. Injection of ATS within 24 hours of injury gives passive immunity while tetanus toxoid (T.T.) gives active immunity. Children are immunised at the age of 6 weeks, 10 weeks, 14 weeks, 4 yrs. 2-3 vaccinations are given during pregnancy. Disease is caused by tetanospasmin reaching the CNS. It begins with headache, chill irritability followed by back pain, stiff neck and spasm of jaw. Ultimately there is lock jaw, spasm of chest, abdomen and spine leading to death due heart failure, suffocation and exhaustion.

viral diseases

VIRAL DISEASES

Viral diseases

Chikungunya

It is a temporarily debilitating disease caused by Alphavirus and spread through mosquitoes, Aedes aegypti

and Aedes albopictus (Tiger Mosquito). Monkey and some humans function as reservoirs. The name chikungunya is derived from Bantu or Makondo language of Africa which means "bent up" because of stooped posture of patients caused by development of arthritic symptoms. It has appeared in good number in India during 2006 with 13,27,636 reported cases and 70 confirmed deaths. The patient has maculopapular (stains and eruptions) rash on limbs and trunk, and arthritis of multiple joints. There is fever (120°F or 39°C) which lasts for about two days. It is accompanied by conjunctivitis and photophobia. Even after disappearance of fever, headache insomnia prostration and arthritis continue for 5-7 days. Chloroquine phosphate has been found to reduce the impact of the disease. Protection against Aedes mosquitoes by use of long sleeves, full pants, socks, windows and doors with wire gauze screens and mosquito repellents are preventive measures. There should be no stagnant water (e.g., coolers) nearby.

Poliomyelitis/Infantile Parmlysis/Polio

It is highly infectious viral disease of infants and

children (hence infantile paralysis) that may attack adults also. Causal agent is a very small RNA containing Polio Virus. Disease is transmitted through faeces, urine and nasal secretions contaminating food, water, drinks, either directly or through flies with an incubation period of 5-17 days. During incubation period, the virus multiplies in alimentary canal. Then it passes to lymph, blood and finally central nervous system in dorsal horn cells of spinal cord and brain stem. Preparalytic stage (1-4 days) is characterised by fever, sore throat, nausea, vomiting, diarrhoea, headache, stiff back, stiff neck, twitching and convulsions. During paralytic stage, motor nerves are affected resulting in atrophy of muscles, generally of arms and legs but may affect those of diaphragm (only iron lung can save), larynx and pharynx (fatal). Vaccine (Salk's vaccine),

Influenza/Flu






Influenza is endemic, epidemic and pandemie. Endemic influenza is localised. It is caused by a Gram negative bacterium Haemophilus influenza. Epidemic influenza spreads throughout the area while pandemic influenza spreads over wide geographical regions. It is viral in origin, occurs in certain regions after every 1-3 years, while globally it recurs every 10-15 years. Asian flu is viral influenza which originated in China in 1957. Influenza virus or Myxovirus influenza is a ribovirus with fragmented genome. It has three forms A, B and C. Mutation rate is high. Certain strains are potent killers. For example, Spanish Flu (1918) claimed 20 million lives. Influenza causes inflammation of upper respiratory tract, nose, throat and eyes. It results in coryza (profound discharge or running nose), sneezing, sore throat, coughing, muscle pains, headache, chill and fever for 4-5 days. Influenza is highly infectious. Incubation period is 2-3 days. Complications include development of bronchitis, ear infection and pneumonia. The disease spreads through direct contact, unclean hands and droplet method. However, it can also attack humans directly from birds e.g., chicken to human beings in Hong Kong (1997). Reservoir is pig which gets it from Water Fowl. Vaccine is available against influenza virus A.

Common Cold/Rhinitis

It is one of the most common infectious diseases of humans which is caused by some 100 types of Rhino viruses, Corona viruses and small bacterium Dialister pneumosintes. The pathogens do not reach the lungs. They infect nose and upper respiratory passage causing inflammation of mucous membranes. There is initation of nasal tract, nasal congestion, flow of mucus, sneezing, sore throat, hoarseness, cough, tiredness, headache and slight fever. Some persons also suffer from allergic rhinitis. Common cold spreads through droplets from talking and sneezing, direct contact, hand shake and common articles of use like pens, pencils, books, cups, door handles, computer key board, computer mouse, etc. It cures automatically after 3-7 days. Medicines are taken to reduce severity of nasal irritation and clearing nasal tract.

Yellow Fever

It is viral fever transmitted from infected

humans (urban type) and infected animals (jungle type) by mosquitoes in tropical Africa and America. The virus is called Flavivirus. It has both mild and sever forms. In sever form it causes fever, hemorrhage, jaundice and renal demage. In mild form it produces fever with inapparent infections. Aedes and Haemagogus mosquitoes act as vectors.

Dengue Fever

It is a viral disease which is caused by viruses DEN-1, DEN-2, DEN-3 and DEN-4, and spread by female Tiger Mosquito or Aedes aegypti and related species. Once infective, the mosquito remains
infective for life. Dengue is of two types:-  
(I) Classical Dengue Fever (Break Bone Fever). It is more severe in adults, starting with mild conjunctivitis or coryza but within hours the patient has high fever, retro-orbital pain, severe splitting headache which increases with movements, backache, breakbone or
joint pains, muscle pain and chill with or without pin-sized vesicles on hinder part of soft palate and rashes on inner side of arms, chest and back. The disorder persists for 5-7 days. It can recur in mildform. 

(ii) Dengue Haemorrhagic Fever (DHF). It is fatal form that starts with fever (101°-105°F), nausea, headache, vomiting, abdominal pain, palpable liver, cold extremities with haemorrhage spots (also on fore-head), internal bleeding leading to blood in stool, urine and vomiting. Blood platelet number falls below 70,000/mm3. It leads to dengue shock syndrome with rapid weak pulse. Paracetamol with replenishment of blood platelets may be helpful. Aspirin and dispirin are harmful. Dengue occurred in India in 1988, 1996 and 2015. In 1996 over 400 persons died of the disease. Vaccine has been developed in Thailand against the disease.

Chicken Pox

It is a contagious and fomite transmitted eruptive viral disease which is more common but less severe in children of upto 10 years and severe but rare in adults. winter and spring are chicken pox time.

The disease is caused by virus varicella zoster with incubation period of 14-16 days. Illness begins with slight fever, shivering and backache. There are then prodormal or transitory rashes with crops of pinkish centripetal spots appearing first on trunk, fore-head and face. Uneasiness, aches and high fever accompany each new crop. Spots turns into fluid filled vesicles and then scabs in five days. Scabs fall off without leaving any mark. Use of boric acid, calamine and benzyl benzoate reduces itching and tendency to scratch. No drug, no vaccine. Antibiotics are given for covering any complication. Passive immunity is possible through zoster immunoglobulins. Single attack gives life long immunity.

Small Pox

It is an eruptive viral disease which has been completely eradicated through widespread compulsory vaccination (10 year Global

Eradication Programme by WHO starting 1966). The last case was reported in Somalia in 1977. WHO declared the planet free from small pox in 1980. The disease is caused by brick-shaped DNA virus called Variola Virus. Infection spreads from oral, nasal, vesicular discharges, pustules and scabs. Incubation period is 12 days. The disease begins with headache, backache, chill, high fever, rashes appearing on third day of illness as reddish spots which change into papules, vesicles, pustules and finally scabs in third week. The spots appear first on the hair line, then face followed over rest of the body but fewer on the trunk. The scabs fall down leaving permanent pox marks, especially over face. Complications include blindness. Death could occur. First vaccination developed by Edward-Jenner (1796) wae against small pox. Disease used to spread through coughing, sneezing and fomite transmission.

Hepatitis (Gk. Hepaticus-liver, itis-inflammation) It is an infectitious disease characterised by inflammation of liver. Hepatitis usually results in blockage of biliary excretion and production of jaundice. Jaundice is a syndrome of hyperbilirubinemia (excessive concentration of bilirubin in blood) and deposition of bilirubin in skin, mucous membranes and sclera resulting in yellow appearance of patient or icterus. Hepatitis is of two types, viral and toxic. Viral hepatitis is caused by viral infection. It is of five types-A, B, C, D (delta) and E.
Hepatitis A

It is also called inflectious epidemic hepatitis or epidemic jaundice. The disease is caused by Hepatovirus or hepatitis A virus (HAV). It is a small sized (27 nm), naked, icosahedral virus which contains a linear single stranded RNA. The virus can withstand heating at 56 degree Celsius for 30 minutes as well as many disinfectants. It is transmitted by faecal-oral route by food, drink or contact. Incubation period is 30 days (15-50 days). In India, the infection commonly occurs in children upto age of 15 years due to poorer hygienic conditions but the disease can occur at any age. Immunity occurs thereafter. A carrier stage is absent. Recovery takes 8-12 weeks. The disease is self limiting. The patient begins to pass HAV in stool even before the onset of symptoms. The virus multiplies in intestinal epithelium. It ultimately reaches liver through blood. There is brief influenza-like illness with fever, malaise, nausea, vomiting, anorexia and liver tenderness. pain may occur in right upper abdominal quadrant. It leads to jaundice. Hepatitis A is, therefore, also called catarrhal jaundice. Diet control and bed rest are required. Antibiotics are given to prevent secondary infection. Since infection can spread from one Person to another, complete hygienic conditions must be observed. Fatality is less than 0·5%. Short term protection can be obtained through injection of immunoglobulin. Vaccine is also available but is Costly.

Hepatitis B


It is popularly called serum hepatitis or transfusion hepatitis. The disease is caused by hepatitis B virus or HBV. It is also called Dane particle. The virus is spherical and double shelled. Genetic material is circular dsDNA. Mature virus has a size of 42 nm. Two subvirion morphological forms are also formed. They are 22 nm diameter spherical and tubular. Virus occurs in blood and body fluids (saliva, mother's milk, semen, vaginal secretion). Therefore, infection can spread through kissing, sharing of safety razor, needlestick injury, use of contaminated needles and syringes, ear and nose
piercing, tatooing, sexual contact, etc. Average incubation period is 90 days (40-180 days). Patient develops malaise (feeling of fatigue), weakness, myalgia (pain in muscles), anorexia, vomiting, pain in right upper abdominal quadrant, pale stool, brownish urine and jaundice. Fatality is less than 1%. Complete recovery occurs in 90-95% cases. Others develop liver complications like active hepatitis,cirrhosis and hepatocellular carcinoma. Even after recovery, many individuals become carrier. Infection can be tested by presence of antigens HBsAg (surface or Australian antigen), HBcAg (core antigen) and HBeAg ('e'antigen). Bed rest, fat free diet and antibiotics are required for protection against aggravation Contact with body fluids should be checked. Vaccine is available. A drug from Phyllanthus amlarus provides relief.

Hepatitis C








It is similar to hepatitis B in being serum or transfusion hepatitis which spreads through needlestick injury, cuts, contaminated needles and syringes, sexual contact, contaminated blood, etc. The virus HCV has single stranded positive RNA. Incubation period is 6-8 weeks but may require several months. Majority of infections are subclinical with milder symptoms, little or no jaundice. As a result the disease remains unattended. It often becomes chronic leading to liver damage, cirrhosis and hepatocellular carcinoma.

Hepatitis D (Delta Hepatitis)

It is caused by simultaneous infection of HBV and delta virus HDV. Delta virus is spherical, 36-38 nm in diameter. It has single strtnded small circular minus sense RNA. The genome can encode only for its nucleoprotein but not the capsid. The latter requires genome of HBV. The support provided by HBV in forming HD virion is called piggy backing. HBV carriers are the worst sufferers
as delta virus can replicate without any long interval. Symptoms are similar to those of hepatitis B but
are more severe and cause large scale damage. Mortality is 20%.

Hepatitis E


It is enterically transmitted non A, non B hepatitis (HNANB). The virus is naked and spherical with a diameter of 27-38 nm. It possesses a single positive stranded RNA. Capsid has characteristic surface depressions. Quite a sizeable number of epidemie, endemic and even sporadic hepatitis cases are due to it. Hepatitis E was first recorded in 1955 in Delhi when some 29000 cases were identified. Like hepatitis A, hepatitis E spreads through faecal contaminated water and food.
Incubation period is 5-6 weeks (2-8 weeks). Symptoms are similar to those of hepatitis A but bilirubin levels are usually higher. Jaundice is deeper and prolonged. Fatality rate is 0·5-3·0% but 10-20% in pregnant women. Carrier stage is absent. Personal cleanliness, boiled water, properly heated, cooked and clean food articles and control of flies are required in period of epidemic. Vaccine is available.

German Measles

It is milder form of measles which occurs in all age groups and is caused by Rubella Virus. Rash appears on fore-head, face and then other body parts. It is accompanied by mild conjunctivitis, headache, swelling of lymph glands (especially posterior cervical) and fever. The disease is harmful if it occurs to pregnant women as it is transferred to foetus through placenta (congenital rubella) resulting in eye defects, deafness and cardiac problems. Immunoglobulins are useful. Vaccination is provided as MMR.

Rabies/Hydrophobia





It is a fatal viral disease (Rabies or Rhabdo Virus) that is transmitted to human beings by biting/saliva of rabid dog or cat. A number of wild animals also carry the virus, e. g., jackals, wolves,
foxes, mongoose, bat, skunk, coyote (prairie wolf) etc. Incubation period is 1-3 months. Multiplication occurs in neurons (nourotrophic). It leads to encephalitis, fear of water, severe headache, high fever, alternate excitement and depression, spasm of throat and chest leading to death. Bitten person should be immediately administered vaccine that develops antibodies before the virus becomes active. The vaccine was developed by Louis Pasteur. Earlier it consisted of 14 inoculations but now 6 doses of vaccine are administered. Dog should be watched for 10 days for the development of rabies symptoms(Running amuck, change of voice, excessive salivation). Stray dogs and cats must be eradicated while pets should compulsorily be immunised. Pre-exposure vaccine is given to forest rangers and naturalists.

Toxic Hepatitis
It is hepatitis or jaundice caused by toxic chemicals called hapatotoxins. The toxins damage or destroy liver cells, e.g., Amanita toxin, carbon tetrachloride, yellow phosphorus, alcohol and some drugs. They many enter the body from any route.

Measles
It is a highly infectious eruptive viral disease of children below the age of five and caused by RNA-containing Rubeola Virus/polynosa morbillorum. Disease is transmitted by 


contact, fomite and droplet methods. Portal of entry is respiratory tract and conjunctiva. Incubation period is 10-14 days. In preeruptive stage (3-4 days), there is hoarseness, cough, sneezing and running nose or coryza due to inflammation of respiratory tract, redness or watering of eyes (conjunctivitis), loss of appetite and fever. Blue-white Koplick's spots (with reddish base) appear opposite molar teeth in buccal cavity on third day. Fourth day begins with itching, skin rash, small raised red spots (rubeola) in crescent shaped groups starting from back of ears, reaching fore-head, face (bloated and blotchy) and then body. By 5-6th day the rashes begin to subside. Antibiotics and vitamin A are given to prevent complications, Vaccination (MMR or Mumps Measles and Rubella) is available which is given at the age of one. Prior to that the infant carries passive immunity from mother.

Mumps
It is an acute infectious one time viral disease of school going children which is characterised by
swollen parotid salivary gland, hence infectious parotitis. Adults without previous infection may
catch the disease. The pathogen ie RNA-containing Paramyxo/Mumps Virus. It is transmitted by direct
contact, droplet method and fomite method. Incubation period is 12-26 days. Due to mumps the
patient has difficulty in swallowing and opening of mouth. There is high fever, chills, headache,
malaise (general body aches), anorexia (loss of appetite). Secondary infections are common especially in
adulte-pancreatis (pancreas), meningo-encephalitis, mastitis (mammary glands), myocarditie (heart),
orchitis (male gonads), saphingo-oophoritis (fallopian tube and ovary). The last two result in infertility.
Antibiotics are given to prevent secondary infection. Vaccination is available (MMR-mumps, measles
and rubella/German measles

Types of diseases

TYPES OF DISEASES

1. Congential diseases.

These are inborn diseases which are present before birth due to defective heredity, physiological disturbance.

e.g., haemophilia, sickel-cell anaemia, alkaptonuria, colour blindness, Down's syndrome, Klinefelter's syndrome, etc.

2. Acquired diseases.

They contracted after birth and are non-inheritable.

Acquired diseases are broadly differentiated into two types :-

A. Communicable or infectious diseases and,

B. Non-communicable or non-infectious diseases.

A. Communicable or infectious diseases :-These diseases can be transmitted from an infected person to a healthy person by means of food, water, air, physical contact or by pathogens/Biological agents. so,are also called infectious diseases.

Depending upon the caustive agents communicable diseases are of following types :-

• Bacterial diseases e.g., whooping cough, leprosy, typhoid, syphilis etc.
• Viral diseases e.g., polio, chickenpox, common cold, rabies, AIDS, japanese encephalitis etc.
  
• Fungal diseases e.g., candidiasis, athlete's foot, ring worm etc.
• Protozoan diseases e.g., sleeping sickness, kala azar, malaria, amoebiasis etc.
• Rickettsial diseases e.g., Rocky mountain spotted fever, typhus fever, trench fever, Q-fever etc.
• Helminth diseases e.g., elephantiasis, trichinosis, taeniasis, liverrot etc.

B. Non-communicable or non-infectious diseases :- These diseases cann't be transmitted from an infected person to a healthy person by any means(like; air, water, food and physical or sexual contact).

These are further of following types on the basis of their caustive agents :-

• Deficiency diseases :- Diseases caused by absence of an essential element (e.g., kwashiorkor, goitet, anaemia, beri-beri etc.
• Degenerative diseases :- These occur due to degeneration of certain body tissue e.g., cardiovascular diseases, stroke diseases and arthritis.
• Allergiec diseases :- These occur due to hypersensitivity of an individual to a foreign substance or agent, known
  as allergens, e.g., asthma, hay fever, etc.
  
• Cancerous diseases :- These occur due to uncontrolled growth and division of cells in certain body tissue leading to tumor formation.

What is health and diseases?

DISEASES