Read this essay to learn about Diseases. After reading this essay you will learn about: 1. Infectious Diseases 2. Minamata Disease 3. Plague 4. Insect-Borne Diseases 5. Allergic Rhinitis (Hay Fever) 6. Asthma 7. Hypersensitivity Pneumonitis 8. Typhoid 9. Amoebiosis 10. Malaria.

  1. Essay on Infectious Diseases
  2. Essay on Minamata Disease
  3. Essay on Plague
  4. Essay on Insect-Borne Diseases
  5. Essay on Allergic Rhinitis (Hay Fever)
  6. Essay on Asthma
  7. Essay on Hypersensitivity Pneumonitis
  8. Essay on Typhoid
  9. Essay on Amoebiosis
  10. Essay on Malaria.

Essay on Disease # 1. Infectious Diseases:

For most people in the world, the greatest environmental health threat continues to be pathogenic (disease- causing) organisms. Although much of our attention is focused on toxic synthetic chemicals, we also should be aware of the biological hazards to which we are exposed.

In the less developed countries, where nearly 80 per cent of the world population live, infectious agents, parasites and nutritional deficiencies still are the main cause of morbidity (illness) and mortality (death).

Gastrointestinal infections (diarrhea, dysentery and cholera) probably cause more deaths worldwide than any other group of diseases. Again, malnutrition and diarrhea create a vicious cycle. Poor nutrition makes people more susceptible to infection and infections, in turn, make it more difficult to obtain, absorb and retain food.

Improved sanitation and better nutrition could prevent most, if not all. Similar other infectious diseases like malaria, parasitic worm infections, tuberculosis and allied respiratory hazards, tetanous, etc., took lives of millions, particularly in poor nations.

Essay on Disease # 2. Minamata Disease:

It was in the early 1950s that fishermen and their families in the city of Minamata, Japan, first began to show the symptoms of what was to become known as the Minamata Disease. The first signs were loss of sensation at the extremities of the hands and feet and in areas around the mouth.

These symptoms were followed by difficulty in walking, slurred speech, reduced vision and hearing loss. Unfortunately, many persons fell prey to eventual paralysis, followed by coma and death.

Public Health Department officials were at first unable to ascertain the cause of such new disease. Similar symptoms were also reported from sea birds and cats in Minamata. Later it was evidently proved that this is a disease of Industrial Toxicity, more precisely “mercury poisoning”. This poisoning of the food chain was local and quite direct. The Chisso Corporation, a plastic manufacturer, was releasing mercury laden wastes into Minamata Bay.

The mercury—in its toxic methyl form—was then concentrated in the predatory fish through food chain of the bay ecosystem. The fisher folk were first to suffer the effect of the disease, for they subsisted largely on fish. By 1976, over 10,000 people were suffering from this disease.

Essay on Disease # 3. Plague:

Plague is often regarded as a scourge of medieval times, from which the world is now largely free. But the latest evidence suggests that incidence of the disease is on the increase. During 1995, at least 1,400 cases of human plague (including at least 50 deaths) were notified to WHO.

The disease occurs particularly in rodents. It spreads from rat to rat and from rats to humans mainly by rat fleas biting first a sick rat and then a person, thus transmitting Yersinia perstis, the bacterium of the disease.

Plague most commonly has two forms: bubonic and pneumonic. The more frequent form is bubonic, in which there is sudden onset of severe malaise, headache, shaking chills, fever and pain in the affected regional lymph nodes. Large and painful lumps appear under the skin, called buboes.

The more dangerous form of the disease is pneumonic or pulmonary plague, which affects the lungs and can be transmitted from person to person by droplets in the air from sputum discharged by the infected individuals.

Some countries in Africa, the America and Asia report cases almost every year. Madagascar, United Republic of Tanzania and Zaire in Africa; Bolivia, Brazil, Peru and the United States in the Americas, and China, Kazakhstan, Mongolia, Myanmar and Vietnam in Asia.

However, cases occur in areas that had apparently been free from the disease for many decades. For example, it has reappeared in Botswana, India and Malawi in recent years after “calm” periods of up to 30 years. Peru experienced a large outbreak of plague in 1984, followed by another in 1990 and again 1992. These outbreaks are linked to cyclical epidemics of plague in rodents.

Over the last 30 years, the mean annual global plague case fatality rate has been 9 per cent, ranging from just over 14 per cent in Africa to just under 6 per cent in the Americas. These high rates persist despite the availability of highly effective drugs against the disease.

Other factors are involved in the apparent increase in plague. In the United States, for example, rapid suburbanization has resulted in increasing numbers of people living in or near areas where plague exists in nature. The number of states of that country reporting plague cases increased from three during 1944- 1953 to 13 during 1984-1994.

Surveillance of plague in rodents indicates that the disease has spread eastwards in the United States to areas believed to have been free of plague during the previous 50 years (up to 1990).

Essay on Disease # 4. Insect-Borne Diseases:

The five main diseases spread by mosquitoes—malaria, dengue, yellow fever, Japanese encephalitis and filariasis—do not lend themselves to a single, comprehensive approach. Each has to be tackled in its own right. At the same time, however, some methods of prevention or control are common to all of them.

Vaccines against yellow fever and Japanese encephalitis already exist and others are being developed against malaria and dengue, although it will be several years at least before they become available. There is an effective drug against filariasis.

The two key measures to prevent the spread of these five diseases are the elimination of mosquito breeding places and the prevention of mosquito bites. The first involves community action, such as covering water storage containers and removing discarded containers from inside and around houses, house-to-house inspection; and control programmes using insecticide sprays.

The second involves people protecting themselves with insecticide-impregnated materials such as curtains and nets, repellents and screens.

Vector and disease surveillance are extremely important, as are rapid intervention and control when an outbreak occurs. Other important measures are health education campaigns and preparations to guard against outbreaks.

Following high-level political commitment for a Global Malaria Control Strategy made in 1992 at a Ministerial Conference in Amsterdam, a target was set for achieving a reduction in malaria mortality of at least 20 per cent by the year 2000 in at least 75 per cent affected countries.

In 1994, the United Nations General Assembly called upon WHO, as the lead agency for health, to promote the international mobilisation of technical, medical and financial assistance to intensify the struggle against malaria. But malaria resurgence in tropical countries were reported in past three decades.

Drugs such as mefloquine and halofantrine have been developed and registered and artemisinin derivatives developed and brought close to registration. In Africa, large-scale multi centre trials of the effectiveness of insecticide-treated bed nets have demonstrated a dramatic reduction in mortality of children under the age of 4. These research-based results are now being translated into operational recommendations for national control programmes.

Essay on Disease # 5. Allergic Rhinitis (Hay Fever):

Characteristic symptoms of hay fever, induced following exposure of the nasal mucosa to the allergen through inhalation, include profuse watery nasal discharge with sneezing, frequently accompanied by redness, irritated and watery eyes and headache.

The inciting allergens are often found in windborne plant structures called aeroallergens. The spores from fungi and even certain algae may persist through the year, especially under warm humid conditions; but particularly in temperate regions, wind-pollinated plants elicit symptoms during certain flowering periods.

In North America there are three peaks in the pattern of seasonal rhinitis: the first occurs in the spring when trees shed their pollen; the second, during the summer months, involves pollen from many grasses as well as late flowering trees and weeds; and the last peak, in the autumn, is typified by weed and secondarily by grass pollen grains. Ragweed pollen (Ambrosia) predominates during this time and is the most allergenic pollen found in North America.

In tropical areas both perennial and seasonal patterns can also be observed with this disorder. Fungal spores and grass pollen are common aeroallergens, whereas those from weeds and wind-pollinated trees are of secondary importance. However, the determination of aeroallergens in the more equatorial zones requires further study.

Although the majority of plants that induce allergic rhinitis are wind-pollinated, a number of plants that are typically pollinated by animals (insects, birds, bats) have also been implicated. For example, old- fashioned roses, which are infrequently found in gardens today, are often heavily scented and their anthers are exposed by the loose and open form of the floral bud.

Thus their attractiveness frequently used to lead to sensitization through inhalation of the pollen and the term rose-fever or rose-cold was used to describe plant-associated rhinitis.

Essay on Disease # 6. Asthma:

Attacks of bronchial asthma are usually precipitated by inhalation of the specific allergen and this form of allergy often has a more chronic course than that seen in allergic rhinitis even though the eliciting agents may be the same. Histamine and, perhaps, serotonin, are involved in symptoms that are characterised by bronchospasm and accompanied with excessive viscid bronchial secretion, which produces the asthmatic “wheezing”.

Extrinsic asthma occurs typically in children and young adults and is often aggravated by emotional factors. It is considered to be an IgE mediated disease caused by the inhalation of aeroallergens such as pollen, spores, feathers and animal dander’s. Although not a common aeroallergen, pollen from the lodge-pole pine of Colorado (Pinus contorta) has also been known to cause bronchial asthma.

The mechanism for induction of intrinsic asthma is somewhat more obscure and is generally found in an older age group. The likely agents are allergic reactions to infectious materials, such as bacteria or viruses, or the inflammatory processes they elicit.

Unlike extrinsic asthma antigens cannot be demonstrated and thus skin testing is of no value. The separation of purely extrinsic from intrinsic asthma can be diagnostically difficult whenever allergic phenomena are combined with infectious factors.

Possibly another IgE-mediated Type I disease is the coffee bean and castor bean workers disease that is characterised by rhinitis, asthma and dermatitis following inhalation of the hapten, chlorogenic acid. As it is widespread in plants and is concentrated in coffee beans and castor beans, chlorogenic acid may act more as a universal allergen than was first suspected.

Essay on Disease # 7. Hypersensitivity Pneumonitis:

Another type of allergic respiratory condition—known as hypersensitivity pneumonitis or extrinsic allergic alveolitis—is often associated with specific professions. In these instances, animal, vegetable or bacterial enzyme material may induce the disease.

For example, inhalation of Thermoactinomyces vulgaris or fungal spores of Microsporum faeni, which can contaminate hay, moldy sugarcane, or mushroom compost, have been causally related to farmer’s (thresher’s) lung, bagassosis and mushroom worker’s lung.

In a similar way, Cryptostroma corticale has been associated with maple bark disease of woodworkers, Penicillum caseii to cheese worker’s disease, Aspergillus clavatus and A. fumigatus to brewer’s lung disease and Graphium and Aureobasidium pullulans to sequoiosis. By inhalation of the enzyme of Bacillus subtilis, those who work with detergents may also develop an allergic pneumonitis.

Diseases produced by inhalation of airborne algae such as Gloecapsa and chlorella, are of more general incidence, however Wood and paper mill workers may also develop bronchial asthma through sawdust inhalation of the Gymnosperms, redwood (Sequoia sempervirens), western red cedar (Thuja plicata), cedar of Lebanon (cedrus libani) and the Angiosperms, iroko or African oak (Chlorophora excelsa), Nicaragua rosewood (Dalbergia retusa), and other exotic woods. The immunopathology suggests that a mixture of many types of immune or allergic reactions may be involved in extrinsic allergic alveolitis and thus is classified as Type III.

It is also possible that symptoms similar to those of allergic respiratory illness may be elicited by inhalation of airborne leaf hairs. Such a series of cases was recently reported among gardeners who had tended saplings of Oriental sycamores or the tree of Hippocrates (Platanus orientalis) at a medical school campus.

It is interesting that, about 2000 years ago, Dioscorides (40-90 AD) had noted watery eyes, sneezing, an irritating sensation in the nasal passages, soreness of the throat, an irritating dry cough and other similar symptoms. 

Essay on Disease # 8. Typhoid:

Typhoid fever is caused by Salmonella typhosa bacteria by ingesting contaminated food or water. Symptoms are characterised by headache, nausea and loss of appetite. About 12 million people get affected by typhoid every year.

Prevention:

Typhoid can be prevented by providing access to safe drinking water, sanitation and good hygiene.

Essay on Disease # 9. Amoebiosis:

This water borne disease is caused by Entamoeba histolytica and is characterised by liquid stools with mucus and blood, hepatitis or abscess. Man gets the infection through cut fruits, salads, vegetables, contaminated water.

E. histolytica are found as motile trophozoites or cysts. Trophozoites cause ulcer in the large intestine. Some amoebas reach liver through portal vein and may cause hepatitis or abscess. Intestinal and hepatic amoebiasis are the main manifestations of the disease. The cysts can survive for 6 to 7 weeks outside the human body, if kept moist and cool. They do not survive at moderate (50°C) temperature.

Diagnosis is based on the detection of Entamoeba histolytica in stool. The antibody of the parasite can be easily detected by Immuno-fluorescence method.

Prevention:

(i) Sanitary disposal of human excreta.

(ii) Drinking boiled and filtered water,

(iii) Protecting food against flies.

(iv)Washing vegetables with disinfectants by iodine solution (200 ppm) or 5% acetic acid. Cysts can be killed in milk by pasteurisation.

Treatment:

The drugs usually prescribed by physicians are:

i. Tnnidazole (1-2 g) to be taken one tablet for 3 days.

ii. Metronidazole (Flagyl) (400-800 mg)—one tablet thrice a day for 5 days.

iii. Furamide (500 mg)—one tablet thrice a day for 7 days.

iv. Entrozyme (250 mg)—one tablet thrice a day for 7 days.

Essay on Disease # 10. Malaria:

Malaria is caused by parasite, Plasmodium and is transmitted by female Anopheles mosquitoes. The credit of this discovery goes to Ross (Kolkata) in 1903. The symptoms are periodic paroxyms of fever, associated with shivering and terminating with sweating. Fever is intermittent and occurs after 3 or 4 days.

Control of Malaria:

(i) Destruction of mosquito by spraying with DDT and oil dissolved in freon in houses.

(ii) Destruction of mosquito larvae in water bodies by spraying with DDT or malathion.

(iii) Eliminating the breeding places in stagnant water pools by spraying with pesticides.

Treatment:

Antimalarial drugs are quinine, chloroquinine and camoquinine etc.

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