Disease Types: Top 10 Major Types of Diseases – Explained!

This article throws light upon the ten major types of diseases. The types are: 1. Water Borne Diseases  2. Enteric Fevers 3. Cholera and Other Acute Diarrheal Diseases 4. Dysenteries 5. Infective Hepatitis 6. Air Borne Diseases 7. Plague 8. Food Borne Diseases 9. Bacterial Food Poisoning 10. Poliomyelitis.

Disease Type # 1. Water Borne Diseases:

The majority of these diseases are commonly spread by contaminated water, although the infractive agent is mainly excreted in the faces and subsequently contaminates the environment. They are intestinal infections such as typhoid, cholera, and other acute di­arrheal diseases, while others are non-intestinal, such as hepatitis A and poliomyelitis.

Much of the ill health in the underdeveloped countries is largely due to lack of safe drinking water. There can be no state of positive community health and well-being without safe water supply. Since the beginning of the 20th century when international cooperation in public health began, safe water has been a major concern.

A survey conducted by WHO in 1975 on Community Water Supplies revealed the fact that, in India, while 80 per cent of the population in water areas had access to community water supplies, only 18 per cent’ of the rural population has reasonable access to safe water.

The WHO attributed the slow pace of progress to shortage of funds and trained man­power, weakness in national programs, difficulties in system operation and maintenance and insufficient involvement of potential users.

Water intended for human consumption should not only be “safe” but also whole­some. A safe water is one that cannot harm the consumer, even when ingested over prolonged periods. Water may be safe, but if it has an unpleasant taste or appearance it may drive the consumer to other, less safe, sources.

Therefore, Drinking Water should be not only completely safe but agreeable to use or wholesome, such a supply may be termed “acceptable or “potable”. Therefore the definition of safe and wholesome water is “free from pathogenic agents, free from harmful chemical substances, pleasant to the taste and usable for domestic purposes”. The causative agents of water and food borne diseases are numerous and include bacteria, viruses, protozoa, and helminths.

The agent normally lives and multiplies in a person who either suffers from specific disease or is apparently healthy. It escapes from the reservoir of infection via the intestinal tract and is subsequently ingested by the susceptible host — either directly or indirectly.

Disease Type # 2. Enteric Fevers (Typhoid and Paratyphoid):

Enteric fevers comprise typhoid and paratyphoid, and are caused by salmonella typhi and S. paratyphi A, B, and C, respectively. In developing countries, typhoid is more prevalent than paratyphoid. The predominant paratyphoid infection in S. E. Asia is paraty­phoid A. Children and young adults are the susceptible population in endemic areas.

It is usually spread through iced drinks, shellfish, inadequately purified water, chlo­rinated-or cross-contaminated between potable and polluted water or sewage. Several types of whole-cell parenteral typhoid vaccines have been developed.

The remedy to be introduced for control of this disease is through epidemiological investigations. Food handlers who are found to be carriers should be kept under surveillance and prohibited from preparations and sale of food to the public as long as they are carriers.

Disease Type # 3. Cholera and Other Acute Diarrheal Diseases:

Cholera is an acute communicable disease of the gastrointestinal tract, caused by the bacteria Vibro-cholerae. The disease occurs in both epidemic and endemic forms.

The disease is spread by the fecooral route, through ingestion of water or food con­taminated by the bacteria from the stool of a cholera patient.

The control of cholera and other acute Diarrheal Diseases is through sanitation mea­sures, immunization and educating the people via medias.

Disease Type # 4. Dysenteries:

Dysentery is an acute communicable disease characterized by gripping pain in the abdomen accompanied by the passage of frequent stools. It may be caused by bacteria or by a protozoan Entameba histolytica – and is called, respectively, bacillary dysentery and amebic dysentery.

It has a worldwide distribution and is endemic. However, epidemics frequently occur where there is poor sanitation. It is more common in children below 10 years. The disease is spread by feco-oral route, through contaminated food and by direct personal contact. Persons transmitting the disease are generally those who observe poor personal hygiene.

Sanitation measures like improved methods of sanitation are of utmost importance in the prevention of dysenteries. In fact, that is how the occurrence of the disease has been considerably lowered in Western countries.

The following measures can be taken for the control and remedies of the disease:

(a) Safe Water Supply:

This is very essential. In rural areas this can be achieved by chlorination of water, replacement of shallow wells by sanitary wells and boiling of drinking water.

(b) Sanitation Barrier:

This implies the proper disposal of excreta so that infection does not reach water, soil, milk, food or flies. This is very crucial as the main source of infection is excreta. A sanitation barrier can be effectively achieved by the constructions and use of sanitary latrines.

(c) Health Education:

It is essential to educate people for improvement in sanita­tion. Apart from that the people should be made specially conscious for improv­ing their personal hygiene, i.e. the importance of washing the hands after defec­tion and prior to handling food must be emphasized. Also, nails must be cut short and kept clean. People must be advised not to eat raw vegetables and fruits with­out washing them thoroughly in running water.

(d) Food and Sanitation:

Boiling and pasteurization of milk help to control the spread of disease. Food should be protected from flies and dusts. Uncovered food, cut fruits and food from roadside vendors should not be eaten. Pre-placement and periodic examination of food handlers should be conducted.

(e) Fly Control Measures:

These include proper disposal of garbage, to prevent fly- breeding, the use of insecticides and protection from flies by screening kitchen with wire gauze mesh for doors and windows.

(f) Immunization:

It is recommended under the Expanded Programme on Immuni­zation (EPI) that all children be immunized with vaccine at the time of entry to school, i.e., at the age of 5.

Disease Type # 5. Infective Hepatitis:

It is an endemic disease characterized by jaundice and caused by a virus. It is common in children and young adults.

The disease is spread by the feco-oral route. The virus is excreted in the stools of the patient and contamination of water and food may lead to explosive outbreaks. It is also spread by direct contact. Therefore, persons living is the same house are at great risk, particularly when standards of personal hygiene are low.

The improvement in sanitation is the only permanent method for reducing the occur­rence of the disease.

The vaccine is now available, therefore immunization in adults and children are ad­vised accordingly.

To sum up about water borne diseases, we must remember one thing — with the advancement of civilization, new diseases are also attacking human race which need special scientific and technology based attention from all advanced nations of the world.

The major water borne diseases prevalent in the under-developing countries are tabulated below.

The routes of transmission as well as the main preventive measures to control these diseases are also outlined.

Disease Type # 6. Air Borne Diseases:

Air borne diseases include only those infectious diseases which are transmitted by air through the respiratory tract into the body. Apart from that, diseases which are not caused by an infectious agent but are caused by inhalation of polluted air, e.g. silicosis, asbestosis.

Air borne diseases, grouped by their causative agents, include bacteria, viz. pharyn­gitis, tonsillitis, bronchitis, pneumonia, mycobacterium tuberculosis, which causes tuberculosis, viruses such as those causing measles, rubella, variola and influenza. Apart from these diseases, the most dangerous and notorious is plague which is caused by bac­teria transmitted by rodents.

Disease Type # 7. Plague:

Plague is transmitted to man mainly through the rat flea which acts as a vector and transmits the disease from infected rodents. The infected rat flea transmits the disease mainly through bites. Pneumonic plague is transmitted from the diseased to a new host through droplet infection. The incubatory period of plague is usually 4-6 days which is followed by symptoms of fever, painful enlargement of lymph nodes, body ache, headache and high fever, breathlessness.

The preventive and control measures of plague include destruction of rats, eradication of fleas, vaccination and chemoprophylaxis of human population. During the period of outbreaks, flea control is of primary importance. Spraying insecticides, e.g. DDT, as also mass vaccination should be done during an outbreak. Rat burrows should also be insuf­flated with the insecticidal dust.

The other important measures to be taken are early diagnosis, Notification, Isolation, Treatment, Disinfection of sputum, discharges from lymph nodes and articles used by the patient, Handling of dead bodies aseptically and Health Education.

For prevention and control the same procedure of water borne diseases cannot be applied for airborne diseases. To whatever degree that air is contaminated, we cannot prevent human beings from breathing it. Specific protection is by immunization only. In general, only certain immunization programmes are carried out in such developing coun­tries and these include diphtheria, pertussi, tuberculosis. Immunization against mumps, measles and rubella are carried out only in those countries which can afford these immu­nization programmes.

Disease Type # 8. Food Borne Diseases:

It is known that water borne and food borne diseases are very much interlinked. There is a large group of communicable diseases in which the infective agent is mainly excreted in the feces and subsequently contaminated the environment. The majority of these dis­eases are intestinal infections such as typhoid, cholera and other acute diarrheal diseases, while others are non-intestinal, such as hepatitis A and poliomyelitis.

As these water borne and food borne diseases are closely related to environmental sanitation, they create major socio-economic and public health problems in many developing countries where basic sanitation and hygiene are inadequate. The most common food borne diseases in the de­veloping countries are Bacterial Food Poisoning, and poliomyelitis.

Disease Type # 9. Bacterial Food Poisoning:

Food poisoning is a general term which refers to an acute attack of gastrointestinal illness with abdominal cramps, nausea, vomiting, diarrhea, with or without fever, ac­quired through ingestion of contaminated food or water. Bacterial food poisoning is usu­ally mild and rarely fatal.

The other food borne diseases are mainly Entameba gingivitis which is generally found to be present in pus-pockets of teeth of pyorrhea infected persons and in the cysts of infected tonsils. It is usually transmitted by cooks who cough into the food at the time of dishing.

Then comes Entameba histolytica which is cosmopolitan in distribution; it is com­monly found in epidemic form in tropical and sub-tropical regions. The trophozoites of this parasite penetrate the wall of the intestine and feed upon its cells causing the forma­tion of ulcers. These ulcers rupture and discharge blood and mucus into the intestine that pass out with the stool.

The fecal contamination of drinking water and raw vegetables or contamination by infected and careless food handling is the mode of transmission of this parasite. Under this category the other diseases which are most prevalent are Entameba Coli, Balantidium Coli, Giardia lambila intestinalis, Schistosoma manooni and Ascaris lumbricoides. The symptoms of all these other than Ascaris lumbricoides have many factors common with Entameba histolytica. But Ascaris lumbricoides — more com­monly known as “Round Worm” — inhabits the small intestine of man and is more com­mon in children, Round worms are cosmopolitan in distribution.

Disease Type # 10. Poliomyelitis:

The most dreadful disease of this group which calls the attention of all is paralytic poliomyelitis, an important childhood disease in developing countries. By the age of four years, more than 90 per cent of the children in some developing countries are already infected. The virus mostly enters by mouth and multiplies in the oropharynx and intestine before invasion of the nervous system.

The infection is mainly spread by close contact with those with apparent infections, either by pharyngeal or intestinal route. The virus is readily, therefore, spread within the family. Indirect transmission by contaminated food, milk, water, and sewage is rare.

To sum up, the main causes of food borne diseases lie with the habits of personal hygiene of the people in general. With improvement in sanitation the chances of infection through food and water become less as the epidemiology and control of all these diseases are generally similar. A system of notification and epidemiological investigation of com­municable diseases should be developed in areas where this is lacking.