Water Borne Diseases
WHO estimates that, in India, about 38 million people are affected by waterborne diseases each year, of which over 75% are children; 780,000 deaths are attributable to contaminated water and more than 400,000 can be attributed to diarrheal alone.
The thirteen common communicable diseases found in India are as follows:
Worldwide, the lack of clean water for drinking, cooking and washing, and the lack of sanitary waste disposal are to blame for over 12 million deaths a year, say researchers. About 1.2 billion people are at risk because they lack access to safe fresh water. India too has its share of infectious epidemics; and though mortality owing to these is decreasing, it is a significant part of the disease burden our society carries.
The most common diseases are as follows :
1) Malaria :
Malaria is a very common disease in developing countries. The word malaria is derived from the word 'mal-aria meaning bad air. Malaria is one of the most widespread diseases in the world.
Each year, there are 300 to 500 million clinical cases of malaria, 90 percent of them in Africa alone. Among all infectious diseases, malaria continues to be one of the biggest contributors to disease burden in terms of deaths and suffering. Malaria kills more than one million children a year in the developing world, accounting for about half of malaria deaths globally.
The risk of getting malaria extends to almost the entire population in India (almost 95 percent). The following states that have the highest number of malaria cases are Madhya Pradesh, Maharashtra, Orissa, Karnataka, Rajasthan, Assam, Gujarat and Andhra Pradesh.
2) Typhoid :
Typhoid fever is an acute, systemic infection presenting as fever with abdominal symp-toms, caused by Salmonella typhi and paratyphi. Before nineteenth century, typhus and typhoid fever were considered to be the same. Enteric fever is an alternative name for typhoid. Salmonella typhi and paratyphi colonise only humans.
The organisms are acquired via ingestion of food or water, contaminated with human excreta from infected persons. Direct person-to-person transmission is rare. Typhoid is a global health problem. It is seen in children older than the age of one.
Outbreak of typhoid in developing countries results in high mortality. The recent development of antibiotic resistant organisms is causing much concern. Typhoid fever is more common in the tropics. It tends to occur in places, where the sanitation standards are poor. A bacterial organism called salmonella typhi causes typhoid fever.
Salmonella paratyphi can also cause fever and abdominal symptoms. The disease caused by both these entities is called enteric fever. The disease presents with a typical, continuous fever for about three to four weeks, relative bradycardia with abdomi-nal pain (due to enlargement of lymph nodes in the abdomen), and constipation.
Indian Statistics Typhoid fever is endemic in India. Health surveys conducted by the Central Ministry of Health in the community development areas indicated a morbidity rate varying from 102 to 2,219 per 1,00,000 population in different parts of the country. A limited study in an urban slum showed 1 percent of children up to 17 years of age suf-fer from typhoid fever every year.
Carriers of Typhoid Fever Typhoid infection is mainly acquired from persons who are carriers of the disease. Carriers are the people who continue to excrete salmonella through their urine and feces a year after an attack of typhoid. A chronic carrier state develops in about 2 to 5 percent of the cases. The organisms in such cases make the gall bladder their habitat.
3) Hepatitis :
Hepatitis is the inflammation of liver. It can be caused by viruses (five different viruses— termed A, B, C, D and E cause viral Hepatitis), bacterial infections, or continuous expo-sure to alcohol, drugs, or toxic chemicals, such as those found in aerosol sprays and paint thinners, or as a result, of an auto-immune disorder.
Hepatitis results in either damage or reduction in the livers ability to perform life-preserving functions, including filtering harmful, infectious agents from blood, storing blood sugar and converting it into usable energy forms, and producing many proteins necessary for life.
Symptoms seen in Hepatitis differ according to the cause and the overall health of the infected individual. However, at times, the symptoms can be very mild. The com-monly seen clinical features are general weakness and fatigue, loss of appetite, nausea, fever, abdominal pain and tenderness. The main feature is the presence of jaundice (yel-lowing of skin and eyes that occurs when the liver fails to break-down excess yellow- coloured bile pigments in the blood).
Depending on the progress and intensity, Hepatitis can be categorized as acute or chronic. In acute Hepatitis, clinical features often subside without treatment within a few weeks or months. However, about 5 percent of the cases go on to develop into chronic Hepatitis, which may last for years. Chronic Hepatitis slowly leads to progressive liver damage and cirrhosis.
Hepatitis A :
Hepatitis A is a self-limiting disease that is found all across the world. It is usually transmitted through oral ingestion of infected material (mainly water), but sometimes transmitted parenterally; most cases resemble the symptoms of a mild flu attack and jaundice is mild too.
Hepatitis B :
Hepatitis B is an acute vital disease. It primarily spreads parenterally, but sometimes orally as well. However, the main mode of spread is intimate contact and from mother to the new born. Fever, anorexia, nausea, vomiting are the initial symp-toms, and they soon lead to severe jaundice, urticarial skin lesions, arthritis, etc. Some patients become carriers or even remain chronically ill, even though most patients recover in about three to four months.
Hepatitis C :
Hepatitis C is a viral disease commonly occurring after transfusion or par-enteral drug abuse. It frequently progresses to a chronic form that is usually asympto-matic, but may involve liver cirrhosis.
Hepatitis D :
Hepatitis D or Delta Hepatitis is caused by the Hepatitis D virus. It usually occurs simultaneously with or as a super infection in case of Hepatitis B, thus increasing its severity.
Hepatitis E :
Hepatitis E is transmitted by the oral fecal route; usually by contaminated water. Chronic infection does not occur but acute infection may be fatal in pregnant women.
4) Jaundice :
Jaundice, also known as icterus, is a condition, which is characterized by yellowish dis-colouration of the skin and whites of eyes. It is a symptom or clinical sign, not a disease by itself. The yellow colouration is caused by an excess amount of bile pigment known as bilirubin in the body. Normally, bilirubin is formed by the breakdown of haemoglobin during the destruction of worn-out red blood cells.
5) Leptospirosis :
Leptospirosis is a disease caused by a type of bacteria and is associated with animals. It is more common in the tropical countries. The disease is also known as canefield fever; cani- cola fever, field-fever, mud fever, seven day fever and swineherd disease. Leptospirosis is caused by different strains of bacteria of the genus Leptospira. Of all the varieties that cause disease, Leptospira icterohaemorrhagiae is the most serious type.
If not treated properly, it could lead to serious complications. Leptospirosis is a disease of animals that can spread to humans. Rats are the most common carriers. Soil contaminated with urine of infected animals can also transmit the disease to persons exposed to cattle urine, rat urine or to foetal fluids from cattle. Sewage workers, agricultural workers, butchers, meat inspectors, workers in contact with contaminated waters and veterinarians are generally at risk.
Person to person transmission is not possible. Leptospirosis can spread due to con-tact with urine, blood or tissues from infected persons. The organisms enter the body through the breaks in the skin or through mucous membranes.
The organisms can also be acquired by drinking contaminated water. Infection is commonly acquired by bath-ing in contaminated water. The organisms multiply in the blood and tissues of the body. Though the organism can affect any organ of the body, the kidney and liver are com-monly involved. The incubation period is usually 10 days. It may vary from 2 to 20 days.
6) Diarrhoeal Diseases :
The term gastroenteritis' is most frequently used to describe acute diarrhoea. Diarrhoea is defined as the passage of loose, liquid or watery stools. These liquid stools are usually passed more than three times a day. The attack usually lasts for about 3 to 7 days, but may also last up to 10 to 14 days.
Diarrhoea is a major public health problem in developing countries. Diarrhoeal dis-eases cause a heavy economic burden on health services. About 15 percent of all paediatric beds in India are occupied by admissions due to gastroenteritis. In India, diarrhoeal dis-eases are a major public health problem among children under the age of 5 years. In health institutions, up to a third of total paediatric admissions are due to diarrhoeal diseases.
Diarrhoea related diseases are a significant cause of mortality in children less than five years of age. Incidence is highest in the age group of 6 to 11 months. The National Diarrhoeal Disease Control Programme has made a significant contribution in averting deaths among children less than five years of age.
7) Amoebiasis :
Amoebiasis is an infection caused by a parasite 'Entamoeba Histolytica. The intestinal disease varies from mild abdominal discomfort and diarrhoea to acute fulminating dys-entery. Extra intestinal amoebiasis includes involvement of the liver (liver abseess), lungs, brain, spleen, skin, etc.
Amoebiasis is a common infection of the human gastroin-testinal tract. It has a worldwide distribution. It is a major health problem in the whole of China south-east and west Asia and Latin America, especially Mexico. It is generally agreed that amoebiasis affects about 15 percent of the Indian popula-tion. Amoebiasis has been reported throughout India.
8) Cholera :
Cholera is an acute diarrhoeal disease caused by V. Cholera (classical or El T). It is now commonly due to the El T or biotype. The majority of infections are mild or symptomatic. Epidemics of cholera are characteristically abrupt and often create an acute public health problem. They have a high potential to spread fast and cause deaths. The epidemic reaches a peak and subsides gradually as the 'force of infection declines. Often, when time control measures are instituted, the epidemic has already reached its peak and is waning.
9) Brucellosis :
Brucellosis is one of the major bacterial zoonoses, and in humans is also known as undulent fever, Malta fever or Mediterranean fever. It is occasionally transmitted to humans by direct or indirect contact with infected animals.
The disease may last for several days, months or occasionally, even years. Brucellosis is both a severe human disease and a disease of animals with serious economic consequences. Brucellosis is a recognized pub-lic health hazard that is found the world over.
It is endemic wherever cattle, pigs, goats and sheep are raised in large numbers. The important endemic areas for Brucellosis exist in Mediterranean zones, Europe, Central Asia, Mexico and South America. Animal Brucellosis has been reported from practically every state in India. However, no statisti-cal information is available about the extent of infection in humans in various parts of the country. The prevalence of human Brucellosis is difficult to estimate. Many cases remain undiagnosed either because they are not apparent, or because physicians in many countries are unfamiliar with the disease.
10) Hookworm Infection :
Hookworm infection is defined as: 'any infection caused by Ancylostoma or Necator'. They may occur as single or mixed infections in the same person through various fac-tors, which have to be prevented. Hookworm infection is widely prevalent in India.
Necator americanus is predomi-nant in south India, and Ancylostoms duodenal in north India. Recently, another spe-cies, A. ceylanicum has been reported from a village near Calcutta. The heavily infected areas are found in Assam (tea gardens).
West Bengal, Bihar, Orissa, Andhra Pradesh, Tamil Nadu, Kerala and Maharashtra. More than 200 million people are estimated to be infected in India. It is believed that 60 to 80 percent of the population of certain areas of West Bengal, Uttar Pradesh, Bihar, Orissa, Punjab, and the eastern coast of Tamil Nadu and Andhra Pradesh are infected with hookworms.
11) Influenza :
Influenza is an acute respiratory tract infection caused by influenza virus of which there are three types—A, B and C. All known pandemics were caused by influenza A strains, due to various factors. Influenza is found all over the world.
It occurs in all countries and affects millions of people. Outbreaks of influenza A occur virtually every year. Major epidemics occur at intervals of two to three years, and pandemics at intervals of about 10 to 15 years. The first pandemic during the present century occurred in 1918-19, which affected an esti-mated 500 million people and killed more than 20 million.
In India alone, over six mil-lion people died during this pandemic. This pandemic was caused by what is now known as the swine influenza virus. Recent pandemics occurred in 1957-58 owing to the influ-enza A (H2N2) and in 1968 owing to the influenza A (H3N2). Outbreaks of influenza B also occur annually with epidemics occurring at intervals of407 years. Influenza brought on by the type C virus occurs sporadically as small outbreaks.
The unique features of influenza epidemics are the suddenness with which they arise, and the speed and ease with which they spread. The short incubation period, a large number of subclinical cases, a high proportion of susceptible population, short duration of immunity, and an absence of cross-immunity, all contribute to its rapid spread. The fate of the virus during inter-epidemic periods is also known. Possible expla-nations include transmission of virus to extra-human reservoirs (pigs, horses, birds. etc.,) latent infection or continuous transfer from one human to another. This explains the occurrence of sporadic cases.
12) Filariasis :
It is caused by a parasite, which belongs to the nematode family Filariasis. According to WHO reports, an estimated 751 million people are at 'risk' for infection, and 120 million have actually been infected. The public health problem of lymphatic filariasis is greatest in China, India and Indonesia. These three countries account for about two-thirds of the estimated world total of persons infected.
Filarial Problem in India :
Filariasis is a major public health problem in India. There are an estimated six million attacks of acute filarial disease per year, and at least 45 million persons currently have one or more chronic filarial lesions. Heavily infected areas are found in Uttar Pradesh, Bihar, Andhra Pradesh, Orissa, Tamil Nadu, Kerala and Gujarat.
The infection is acquired from a person who has filariasis. The maximum infectivity is when the organisms are circulating the blood. The largest number appears in the blood at night time, and retreats from the blood stream during the day. Their usual habitat is in the lymph nodes.
The mosquito feeds on such a person and acquires the filarial parasite. The filarial organism is transmitted when the mosquito bites a person. The parasite is deposited near the site of puncture. It passes through the punctured skin or may penetrate the skin on its own and finally reach the lymphatic system. Filariasis affects all age groups.
Causative Factors which Favour the Spread of Disease :
Filariasis is seen mainly in developing countries. Lymphatic filariasis is often associated with urbanization, indus-trialization, illiteracy, poverty and poor sanitation. Migration of people favoured the spread of filariasis. The movement of people from one place to another has led to the extension of filariasis into areas where filariasis was not so prevalent. It largely explains the presence of filariasis in the urban areas of the Third World countries.
Climate is an important factor in the epidemiology of filariasis. Regions which are damp and moist and have stagnant water all year round afford a good breeding ground for mosquitoes. It influences the breeding of mosquitoes, their longevity and also deter-mines the development of parasite in the insect vector.
13) Tuberculosis :
Tuberculosis remains a worldwide public health problem, particularly in the Third World countries. Tuberculosis is India's biggest public health problem. An estimated that 5, 00,000 deaths annually are reported due to this disease, while a similar number of persons get cured.
The population in the Third World countries like India is exposed to tuberculo-sis. The disease, however, does not develop in everyone who is exposed. Poor nutrition, overcrowding, low socio-economic status, are more likely to develop the disease.
The prevalence of people who are infected is about 30 percent of the population. The prevalence of infection is more common in the younger population. The vast majority of cases are to be found in rural and semi-urban areas, where more than 80 percent of the country's population lives. In urban areas, tuberculosis is found more frequently in slum-dwellers and lower socio-economic groups than in well-off groups.