Classification of infective diseases in relation to water supplies:
I. Water borne diseases (fecal-oral):
(a) by bacterial organisms: cholera, typhoid, paratyphoid, dysentery, diarrhea, weil’s disease (leptospirosis) and tuberculosis
(b) by phage virus or bacteriophages: infectious hepatitis, jaundice and poliomyelitis
(c) by protozoan: amoebic dysentery, ascarsis and amoebic meningo cephalitis (fatal encephalitis usually acquired while swimming in ponds)
Preventive measures: improve quality of drinking water. Prevent causal use of the unhygienic sources.
II. Water washed diseases:
Scabies, skin diseases, typhus fever, leprosy, trachoma, conjunctivitis and bacillary dysentery
Preventive measures: increase water quantity for (washing/cleaning) use. Improve accessibility and reliability of domestic water supply.
III. Water based diseases:
Schistosomiasis (liver fluke), dracunculosis (guinea worm disease)
Preventive measures: control snail populations; filter the water through a fine mesh cloth to remove larvae/cyclops/snail. Disinfect contaminated water.
IV. Water related diseases (by vector organisms):
Malaria, filaria, dengue fever, sleeping sickness (African sleeping sickness)
Preventive measures: destroy breeding sites of insects. Decrease the need to visit breeding sites. Use mosquito nets.
Water borne diseases of biological origin
| S.No | Disease | Causative agent/Type of organism/Life cycle (pathogenicity) | Clinical features |
|---|---|---|---|
| 1. | Dracunculiasis (guinea worm infestation) | Dracunculus Medinensis / Nematode worm / Adult stage in human host larval stage in fresh water crustaceans cyclops | A stinging / burning sensation heralds the appearance of a blister, which ruptures to form an ulcer when the site of the skin is placed in water. The symptom appears when the female worm reaches the skin surface and is ready to discharge her larvae. Occasionally, there may be generalized symptoms of rticaria, nausea, vomitting and dyspnoea when the blister first appears. |
| 2. | Schistosomiasis [group of diseases lschistosome dermatitis (swimmer's itch), katayamafever, urinary schistosomiasis, intestinal schistosomiasis, hepatic schistosomiasis] | schistosoma haematobium, s. mansoni, s. japonicum, s. intercalatum, s. mekongi / Trematode flatworms / For s. mekongi (usage of only lowercase characters suggested) host is dog - for other species host is man - eggs are passed in the urine or faeces - in fresh water, the first larval stage, a miracidium penetrates body of freshwater snail - within the snail miracidia multiplies asexually to form numerous sporocysts - after 4 to 6 weeks released from snail as free swimming cercariae - cercaria penetrates the skin of man | Schistosome dermatitis (swimmer's itch): it is caused due to the penetration of the free swimming cercariae through the skin. It is an itchy popular skin rash, which occurs within about 24 hours. The eruption is probably allergic in nature. Katayama fever: this occurs about 4 to 6 weeks after infection, usually due to s.japonicum or s.mansoni and rarely to s.haematobium. There is an acute onset of fever, headache and cough. There is also enlargement of the liver, spleen and the lymph nodes. Examination of the blood film shows eosinophilia. Occasionally, katayama fever results in death. Urinary schistosomiasis, especially when the infestation is light, is frequently asymptomatic. Painless haematuria is usually the first sign. Terminal haematuria, passing small amounts of blood at the very end of micturition is characteristic. More serious disease is due to damage of the bladder and kidneys, as a result of obstruction to the flow of urine. Severe contraction of the bladder can occur, with fibrosis and calcification. Intestinal schistosomiasis can also be asymptomatic in light infestations. Patients may complain of fatigue, abdominal pain and diarrhoea, which can be bloody. Anaemia is common due to the blood loss. There is polyp and ulcer formation, which can occasionally cause bowel obstruction. Hepatic schistosomiasis can occur when there is a heavy infestation. This usually presents as a symptomless hepatomegaly, with or without enlargement of the spleen. In advanced cases portal hypertension may develop, with massive enlargement of the spleen and the appearance of oesophageal varices, which can bleed repeatedly. |
| 3. | Giardiasis | giardia lambia (g.duodenalis)/Protozo / g. lambia exists in two forms. The trophozoites found adherent to the mucous membranes of the upper small intestines - passed along the intestines - passed in the faeces - in the new host passes into the duodenum - produces two daughter trophozoites which then colonize the small bowel. | In symptomatic patients, the predominant feature is the acute onset of diarrhoea, which is often explosive, abdominal cramps, bloating and flatulence. There is no blood or pus in the stool, which is often pale and at times almost white in color. Malaise is common and sulphuric belching is quite characteristic. Untreated, the acute illness usually lasts for at least 10 days and often for much longer (4-12 weeks). During this illness patients often lose considerable weight. |
| 4. | Cryptosporidiosis | c. parvum (above 20 species are now known, of which c. Parvum pathogenic for humans) / protozoa / oocyst is ingested and passes through the stomach -excystation occurs with release of four motile sporozoites - sporozoites attach to the epithelial cell wall - sporozoite matures into a trophozoite -divides forming a meront and releases merozoites - microgametes and macrogametes formed and fertilize - zygotes formed and matured as oocyst - oocyst is the infective stage and is passed in the faeces. | Diarrhoea stools, watery and offensive and contain mucus or slime, but rarely pus or blood cells. Patients may also complain of mild abdominal pain and a few also have a mild fever. Symptoms usually last from 2 to 26 days. In individuals suffering from aids, the disease is much more severe and more persistent. Illness can last for several months or until death. |
| 5. | Cyclospora | Cyclospora cayetanensis / Protozoa / life cycle not known | Diarrhoea, abdominal pain, nausea, vomiting and anorexia. Flatulence and bloating are also features. The diarrhoea is characteristically prolonged, lasting from one to eight weeks. |
| 6. | Naegleria (free-living amoebo flagellate) | naegleria fowleri / Amoeboflagellates / n. Fowleri has three stages in its life cycle - in trophozoite stage (found in mud and surface of vegetation) the organism feeds and multiplies - motile biflagellate stage is found in surface layers of water - finally, the organisms are found as cysts - both trophozoite and biflagellate forms are potentially infectious for humans - infection occurs during swimming - pathogens penetrate through the nose - enters cerebrospinal fluid - finally penetrates and feed on brain. | Primary amoebic menigoencephalitis (pam). Initial symptoms are headache and a slight fever. Vomiting, stiff neck, increasing fever and severe headache leads to coma. |
| 7. | Illness caused due to cyanobacteria | Cyanobacteria / Algae (but truly prokaryote bacteria)/Illness related to cyanobacteria is mediated by toxins - toxins include hepatotoxins, neurotoxins and lipopolysaccharides. | Clinical presentation of disease that implicates cyanobacteria is wide. The commonest clinical presentation is a self limiting diarrhoea, which lasts for a few days. Erythematous skin rashes are also commonly described. |
| 8. | Cholera and other vibrios (gram.negative, neotile, comma shaped bacilli) | Vibrio cholerae / Bacilli/the infectious dose is high i.e. 106 to 108 organisms. If gastric acidity is neutralized, then the infectious dose falls to as low as 103 organisms. The organism proliferates in small intestine - penetrates mucus barrier to attach to the mucosal surface - colonizes the lining of gut -secretes a potent enterotoxin - intracellular level of cyclic adenosine monophosphate (camp) increases - increased secretion of chloride and inhibition of sodium uptake. | Painless watery diarrhoea. In mild cases, faeces are passed 2-3 times per day for 5-7 days. In a typical severe case, passage of copious water stool can be continuous. Within a matter of a few hours the stool becomes colorless, known as rice-water stool. The life threatening effects of cholera are due to the rapid depletion of body fluids. Shock can develop within 4 - 12 hours, with death soon after. Complications include renal or cardiac failure due to the dehydration of the body. Metabolic acidosis due to loss of bicarbonate in the stool. |
| 9. | Typhoid and paratyphoid | Salmonella typhi and salmonella paratyphi/ bacilli / Infectious dose is below 1000 and possibly 10 organisms. After passing through the stomach, the organism penetrates the lining of the small bowel - then passes to the mesenteric lymph nodes and multiplies - the organisms are then released into the blood stream -any organ can be infected, gall bladder is mainly infected - again intestine is affected, perforation of intestine occurs - increase in the excretion of infective agent in the stool. | Diarhoea, watery stool with blood, colicky abdominal pain and fever. Nausea and mild vomiting. |
| 10. | Shigellosis (bacillany dysentery) | Shigella dysenteriae, shigella flexneri, shigella boydii, shigella sonnei/ bacilli/ can cause disease in healthy adults with the administration of fewer than 200 viable organisms. The disease is produced by invasion and subsequent destruction of the superficial mucosa. | Diarrhoea accompanied by vomiting and leading to dehydration. Then fever, meningism and severe abdominal pain may occur/ diarrhoea mostly mucous with varying amounts of blood/ cholera type illness with watery diarrhoea or with a gangrenous form. May be associated with severe abdominal pain and the passage of stools containing altered blood and necrotic mucosa (lining of the bowel wall). |
| 11. | Campylobacterios | Campylobacter spp/ bacilli/ these are sensitive to stomach -acid and infection is enhanced by the buffering effect of foods. | Diarrhoea with watery and occasionally bloody. Pus in the faeces. Cramping abdominal pain and can mimic appendicitis, acute crohn's disease and ulcerative colitis. Fever and malaise are also features. |
| 12. | Escherichia coli | Escherichia coli/ bacilli/ adhere to gut wall and produce toxins. | Urinary tract infections, meningitis and septicaemia. Cause dehydrating diarrhoea in children. It is a common cause of traveller's diarrhoea. In infants can cause fever and watery mucoid diarrhoea. |
| 13. | Yersinia infections | Yersinia pestis/ bacilli/ infective dose is high, up to 109-infection of the terminal ileum leads to ulceration and inflammation of the mesenteric lymph nodes. | Affects children under five years. It causes fever, diarrhoea and abdominal pain which lasts for about one to three weeks. |
| 14. | Plesiomonas infections | Plesiomonas shigelloides/ bacilli/ pathogenic mechanism not known. | Gastroenteritis. Mild to severe mucoid and bloody diarrhoea. In some cases bacteraemia, osteomyelitis, septic arthritis and meningitis. |
| 15. | Aeromonas infections | Aeromonas hydrophila, aeromonas caviae, aeromonas sobria/ bacilli/ pathogenesis unclear. | To start with mild, self limiting diarrhoea then develop fever, abdominal pain and bloody diarrhoea. |
| 16. | Pseudomonas infections (aerobic, non- spore forming, gram negative bacilli) | Pseudomonas aeruginosa/ bacilli/pathogenesis differs with the syndrome and source of infection. | Respiratory infection, bacteraemia, meningitis and brain abscess, and ear, eye, bone and joint, urinary tract, gastrointestinal, and skin and soft-tissue infections. The most water-related skin rash is folliculitis. |
| 17. | Melioidosis | Burkholderia pseudomallei/ bacilli/causes purulent abscesses, which can affect several body systems. | Asymptomatic infections. Clinically melioidosis may present as an acute localized suppurative lesion, an acute pulmonary or septicaemic illness or as a chronic suppurative infection. |
| 18. | Legionnaire's disease | Legionella pneumophila/ bacilli/ enters the lung by direct inhalation of aerosols. | Pneumonia, pontiac fever (self limiting, influenza like illness characterised by malaise, myalgia, fever, chills and headache. |
| 19. | Leptospirosis | Leptospira interrogans, l.biflexa, l.parva/ obligate aerobes/ gains access to the bloodstream, either through intact mucous membrane, conjunctivae or damaged skin. Bacteraemia then carries the organisms to sites throughout the body including the liver, kidneys, csf and eye. Multiplication at these sites is then responsible for end-stage disease. | Non-specific flu-like illness, which lasts for three to seven days. Sudden onset of high fever, prostration, rigors and muscle pains headache, photophobia and abdominal pain. |
| 20. | Mycobacterial disease | Mycobacteria ulcerans, m. Avium (usage of the same case suggested), m.gordonae, m.marinum/ bacilli/ the skin diseases follow inoculation of the bacterium into the skin. Other infections follow from inhalation. | Tuberculosis and leprosy. |
| 21. | Tularaemia | Francisella tularensis/ bacilli/ infection through skin abrasion or by inhalation. Initially, organisms reproduce at the site of entry for three to five days. From here, they are spread to regional lymph nodes, followed by bacteraemia. Disseminated infection can affect several organs, causing focal necrotic lesions and granulomas. | Clinical disease can be either of the cutaneous-lymphatic type where a nodular, suppurative or ulcerative lesion develops at the site of entry. In the typhoidal presentation the main feature is high fever with occasional pneumonitis. |
| 22. | Helicobacter infections | Helicobacter pylori/ bacilli/ pathogenesis not known. | Nausea and abdominal pain which lasts for 3 - 14 days. Gastritis develops hypochlorhydria may persist for up to a year. In most patients, infection persists for several years or more. |
| 23. | Viral hepatitis | Hepatitis A, hepatitis B/ virus/ acquired orally - virus passes through the stomach, where it replicates in the lower intestine before being carried to the liver, where most replication occurs. Virus is shed from the liver in the bile, from which it contaminates the faeces. Liver damage occurs at the point when circulating antibody appears in the blood. | Jaundice. Initial symptoms are non-specific, and include malaise, lassitude, myalgia, arthralgia and fever. Inflammation of the liver, darkening of the urine and pale or clay colored stools. |
| 24. | Viral gastroenteritis | Rotaviruses (a, b & c)/ virus/ rotaviruses replicate in the villus epithelial cells of the small intestine and causes a loss of the absorptive cells. | Fever, vomiting and diarrhoea. |
| 25. | Enterovirus infections including poliomyelitis | (1) polio virus (2) coxsakie viruses A (3) coxsackie viruses B (4) echoviruses (5) enteroviruses/ virus/ infection follows the ingestion of faecally contaminated material. Initial site for replication is the submucosal tissue of the pharynx or distal small intestine. From the gut, virus may then spread directly to regional cervical or mesenteric lymph nodes or via the blood to various reticuloendothelial tissues such as liver, spleen, other lymph nodes and the bone marrow. Replication may then cease. | (1) aseptic meningitis, encephalitis, paralytic-poliomyelitis. (2) aseptic meningitis, encephalitis, paralytic disease, hand, foot & mouth disease; ulcerative stomatitis, lymphonodular pharyngitis, acute catarrh; pneumonitis, hepatitis; conjunctivitis, splenomegaly. (3) aseptic menigitis, paralytic disease, pericarditis, myocarditis, hepatitis, conjunctivitis, splenomegaly. (4) paralytic disease, respiratory -enteric disease, gastroenteritis, conjunctivitis. (5) paralytic poliomyetitis, epidemic conjunctivitis. |
| 26. | Adenoviral infections | Adenovirus a,b,c,d,e&f/ virus/ virus infects the cell, replicates to produce up to a million new viruses and then kills the cell by lysis to release new infective particles. | Gastroenteritis, pharyngitis and conjunctivitis. |
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