6 Major Water Borne Diseases Part I

Dr. Sunil Mittal

7.1         Introduction

Water is one of the essential components for human life. The contamination of water with various biotic and abiotic elements leads to negative effects on human health. These negative effects include various acute and chronic diseases, collectively known as water related diseases. In water related diseases, water borne diseases are more dangerous due to the involvement of viral, bacterial and parasitic infections and pathogenesis. These infections use water as a common means of transmission. These transmissions results from direct or indirect exposure to water through consumption and skin exposure during bathing and recreational use of water. Historically, first scientifically documented outbreak of water borne disease occurred in London, England, in 1854. In this event, John Snow, a prominent local physician, reported that the consumption of water from a sewage-contaminated public well led to cholera. The WHO in 2004 reported that there are 2.1 million deaths from diarrheal diseases every year in the world, most of them being children. Further it is also reported that approx. 65% of these deaths could be prevented by water hygiene and sanitation interventions. The top five water borne diseases are cholera, diarrhea, malaria, Typhoid and dysentery. In India as per the data given in the National Health Profile published by Central Bureau of Health Investigation (Ministry of Health and Family Welfare), approximately 32 crore cases and 10 thousand deaths were recorded between 2011-2013, due to the bacterial based water borne diseases like Acute Diarrhea, Typhoid and Viral Hepatitis.

7.2         Classification of water related disease

Water associated or water related disease covers a wide range of disease in which water plays a major role (figure 1). These diseases can be classified in the six categories. These are

1. Water hygiene diseases: Diseases whose incidence, prevalence and severity can be reduced by the use of clean and safe water for personal and domestic hygiene e.g. Scabies, Shigellosis.

2. Water contact diseases: Diseases caused by skin contact with microbial, pathogens and chemical contaminated water e.g. Schistosomiasis.

3. Water based chemical diseases: Disease caused by contact and consumption of water contaminated by some chemicals e.g. Arsenicosis.

4. Water aerosol diseases: Disease caused by inhalation of water aerosols containing water suspended pathogens and chemicals e.g. Gestroentrosis.

5. Water scare disease: Diseases transmitted through inadequate sanitations due to the scarcity of water. e.g. Trichuriasis or whipworm infection

6. Water Borne microbial diseases: Diseases caused due to the presence of virus, bacteria and parasites in the drinking water sources. e.g. cholera, diarrhea.

Among all the water related diseases, Water borne microbial diseases are the most common and frequent diseases. These diseases are further classified on the basis of their causative agents. It may be bacteria, virus, protozoa and worms. In this chapter various bacterial and viral water borne diseases are discussed along with their symptoms and preventive majors.

7.2.1     Water Borne Bacterial Diseases

Water borne bacterial diseases covers all those bacterial infections which transmitted through the use of bacterial contaminated water (figure 2). The contaminated water may be used for the drinking purpose, food preparation and bathing. The major reason of water contamination by bacteria is faces of warm-blooded animals (birds and mammals) (figure 3). Major water borne bacterial diseases are cholera, typhoid fever, dysentery, Brainerd diarrhea and Botulism.

7.2.1.1 Cholera (Causative agent: Vibrio cholera)

Pathogenesis: Vibrio cholera inhabits in the small intestine and discharges enterotoxin which results in considerable outburst of fluid from the intestinal wall (figure 4).

Incubation Time: 2-3 days

Symptoms and signs: Thirst due to dehydration, sunken eyes, wrinkled skin, postural hypotension, weakness and oliguria progress fast.

Clinical features: Incubation period of 24 – 48 hours develops sickness which is initiates with abrupt watery diarrhea followed by vomiting.

Treatment

• Sufficient amount of liquid and electrolyte (oral or intravenous) should be replenished.
• Specific treatment with antibiotic like Tetracycline, Doxycycline.

Prevention and Control

• Provision of safe water, proper sanitation, and food safety are critical for preventing occurrence of cholera.
•  Health education for proper sanitation and hygiene especially in developing countries.

7.2.1.2 Typhoid fever (Causative agent: Salmonella typhi)

Pathogenesis: After entering the body through ingestion of contaminated food or polluted water, the bacterium breaches the mucosal barrier at the colon and distal ileum where their intracellular proliferation takes place. The bacteria then results in persistent fever and an inflammatory response is induced due to attack of bacterium to gall bladder and intestine (figure 5).

Incubation Period: 8–14 days

Symptoms and signs: continued restiveness, spleen and liver expansion. Development of rashes called “rose spots” which are small red spots on the abdomen and chest.

Clinical features: Extended and stubborn fever and daily rise in temperature up to 40-41°C, connected with headache, chills and malaise.

Treatment & Diagnosis: Vidal test is widely used in the diagnostic of typhoid fever. Patients treated with an antibiotic may fever for 3–5 days, although the height of the fever generally decreases each day. Patients may actually feel worse during the several days because of weakness arises due to long fever.

Prevention and Control: Frequent hand-washing in hot, soapy water is the best way to control infection, an alcohol-based hand sanitizer for times when water isn’t available. Avoid raw fruits and vegetables, drinks with ice, old and preserved foods.

7.2.1.3 Bacterial dysentery (Causative agent: Shigella)

Pathogenesis: Bacteria of the genus Shigella – secrete substances known as cytotoxins, which kill and damage intestinal tissue on contact (figure 6).

Incubation period: 12 hours to 7days

Symptoms and Clinical features: The most common symptoms normally consisting of mild stomach pains and frequent passage of stool or diarrhea. The large volume of liquid feces passed, with the presence of mucus, pus and blood. Vomiting, rapid weight-loss, and muscle aches also caused during dysentery.

Treatment & Diagnosis: For bacterial infections such as shigella, the diagnosis is carried out by culture of the stool. Antibiotics like ciprofloxacin, ofloxacin, levofloxacin, or azithromycin are used to treat the organisms causing bacillary dysentery. In normal cases, soft drinks, juices, and bottled water will be enough. More severe cases should be treated with solutions that contain electrolytes such as potassium, salt, and sucrose.

Prevention and control:

Consumption of cooked foods that have been heated to a high temperature is recommended. Consumption of cooked foods that have cooled down should be avoided. Boiled water should be used for cooking and other purposes such as to wash and to cook food in, to wash hands, and to brush teeth. Consumption of fruits without peel should be avoided.

7.2.1.4 E. coli Enteritis or Acute Gastroenteritis or Stomach flu (Causative agent: E. coli)

Pathogenesis: Watery diarrhea causes by enterotoxic E.coli. The bacterial toxin produced by this organism acts upon the upper small intestine. The bacterium causes inflammatory diarrhea by incursion of the colon (figure 7).

Incubation period: 3 to 4 days

Symptoms and Clinical features: Most strains of E. coli have incubation period of typically 10 hours to 6 days. It causes acute onset of watery diarrhea that is usually minor and self-limiting. It infection also causes abdominal cramps, anorexia and maliase.

Treatment & Diagnosis: Diagnosis done by stool culture to test for the presence of disease-causing E. coli. Drinking fluids and hydration of body is extremely important. If body does not become hydrated due to intense vomiting or diarrhea, intravenous fluid therapy is necessary.

Prevention and control

• Avoid raw fruits or vegetables that have not been washed well.
• Avoid uncooked meats or eggs.
• Use the Water from a well or stream after treatment.
• Supply treated water in city or town water.

7.2.1.5. Botulism (causative agent: Clostridium botulinum)

Pathogenesis: Botulism can be spread several different ways. The bacterial spores which cause it are found in both soil and water. They produce the botulin toxin when exposed to low oxygen levels and certain temperatures (figure 8).

Incubation period: 12-36 hours

Symptoms and Clinical features: The disease begins with weakness, trouble in seeing, feeling tired, and trouble in speaking. This may then be followed by weakness of the arms, chest muscles, and legs.

Treatment & Diagnosis: For botulism, diagnosis should be made on signs and symptoms. Confirmation of the diagnosis is made by testing of a stool or enema specimen with the mouse bioassay. Botulism is generally treated with botulism antitoxin. Supportive care is also required for botulism which includes monitoring of respiratory function. In some abnormal cases, physicians may try to remove contaminated food still in the digestive tract by inducing vomiting and using enemas.

Prevention and control:

•  Use good quality and fresh produce.
•  Use foods which are sufficiently acidic (for example, lemon juice, citric acid or vinegar).
•  Consume properly heated and processed Food.
•  Fermented food making should be properly done.
• Avoid consumption of foods from damaged cans or bottles

Keep food below 5°C and heat above 60°C before consumption

                                                       Figure 8: Botulism transmission

7.2.2     Water Borne Viral Diseases

Water borne viral diseases can get transmitted through contact or consumption of the virus contaminated water. The virus is known for their parasitic nature. The major water borne viral diseases are Hepatitis A, Viral gastroenteritis, Poliomyelitis, SARS (Severe Acute Respiratory Syndrome).

7.2.2.1 Hepatitis A (Causative agent: Hepatitis A Virus)

Pathogenesis

• Transmitted exclusively by fecal oral route. A typical Hepatitis virus is illustrated in figure 9.
• Its transmission takes place due to poor particular hygiene and overcrowding.
• Viral multiplication is restricted to the liver but virus may be present in the blood, liver, bile, and stool after the late incubation period.

Incubation Period: 14–28 days

Clinical Features

The clinical features usually occur in three phases.

1. Asymptomatic cases: – common, especially in children.
2. Prodromal symptoms: symptoms like cough, headache, anorexia, vomiting, myalgia, low grade fever, photophobia, etc.
3. Clinical jaundice: occurs 1 – 2 weeks after the prodromal symptoms. 1 to 5 days earlier to onset of clinical jaundice, urine becomes dark and stool becomes clay

colored. In some cases, cervical adenopathy hepatomegaly and splenomegaly may occur.

Treatment & Diagnosis: abnormal liver function tests like alkaline phosphates, aspartate aminotransferase (AST), alanine aminotransferase (ALT) and bilirubin. Specific diagnosis may be done through serology. Acute viral hepatitis has no specific therapy. Treatment requires care and rest with high calorie diet.

Prevention and Control:

•  Maintain personal hygiene and proper sanitation help prevent the spread of the HAV virus. Practices of hands wash with soap and water after using the bathroom, changing a diaper, and before preparing, serving, or eating food.
•  People who have hepatitis A should not be preparing or serving food, or caring for the elderly or for young children, until at least 2 weeks have passed since the first sign of hepatitis A illness.
•  Boiling or cooking food and drinks for at least 1 minute to 185°F (85°C) inactivates HAV. Foods and drinks heated to this temperature and for this length of time do not transmit HAV infection unless they become contaminated after heating.

7.2.2.2 Poliomyelitis (Causative agent: Poliovirus)

Pathogenesis: once inside the body, epithelial cells in the intestinal mucosa are infected by the virus, which further extents and replicates in the sub mucosal lymphoid tissue. This is followed by invasion of virus to regional lymph node and the blood stream. A typical polio virus is depicted in figure 10.

Incubation Period: 7 to 21 days

Clinical features

• Maximum infections are asymptomatic.
• Some patients may develop slight sickness exhibited by sore throat, fever, headache, malaise, myalgia and anorexia.
• A less common clinical feature is paralytic disease due to paralysis of lower motor neuron.
• Severe muscle, neck and back pain may be preceded by quick or slow progress of paralysis.
• Unequal weakness commonly disturbs the lower limbs.

Diagnosis

• Stool culture is the most common diagnostic tool, which may be accompanied with cultures of other body fluids.

Treatment

• Vaccination is available (live attenuated oral vaccine).
• Appropriate Care and rest.

Prevention and Control:

There is a vaccine available to prevent polio. All healthy children between the ages of six weeks and 6 years should be vaccinated against polio as part of their complete vaccination schedule.

                    7.2.2.3   Acute Viral Gastro- enteritis (Rota Virus)

Pathogenesis

Small intestine is infected by the virus, which reduces absorption and causes diarrhea. A typical Rota virus is depicted figure 11.

Incubation Period: 7 to 21 days

Clinical Features

Incubation period ranges from 2-4 days, which causes mild to severe diarrhea initiated by sudden inception of vomiting. Mucus is commonly found in the stool. It is commonly related with severe dehydration.

Treatment

The treatment of rotavirus diarrhea is based primarily on replacing fluids and electrolytes, as directed by the estimated degree of dehydration. Oral rehydration therapy is recommended for preventing and treating early dehydration and continued replacement therapy for ongoing loses. Shock, severe dehydration, and unconsciousness require intravenous therapy.

7.2.2.4 Severe acute respiratory syndrome (SARS) (SARS corona virus) Pathogenesis: The pathogenesis of SARS is highly complex, with multiple factors leading to severe injury in the lungs and dissemination of the virus to several other organs. The SARS coronavirus targets the epithelial cells of the respiratory tract, resulting in diffuse alveolar damage (figure 12).

Incubation Period: 2-7 days

Clinical Features: Initial symptoms are flu-like and may include sore throat, cough, fever, myalgia, lethargy and other nonspecific symptoms. The most common symptom is fever above 38 °C (100 °F). SARS may eventually lead to shortness of breath and/or pneumonia; either direct viral pneumonia or first bacterial pneumonia.

Prevention and Treatment:

Till date there is no known vaccine for SARS, and segregation and confinement is the most effective means to avert its spread. Other precautionary actions include:

Wash hands frequently

Wear surgical mask when communicating with SARS infected person. Avoid contact with bodily fluids of infected personal.

Wash the personal items of SARS infected person in hot, soapy water (eating utensils, dishes, bedding, etc.)

Keep children with symptoms at home (away from school).

                                                                  Figure 12: SARS corona virus

7.2.2.5                 Coxsackie A disease (Hand, foot and mouth disease) (Coxsackie A virus)

Pathogenesis: Coxsackie virus’s genome contains linear single-stranded RNA. They are non-enveloped viruses divided into two group A and B. Group A coxsackie viruses have a tendency to infect the skin and mucous membranes, which causes hand-foot-and-mouth (HFM) disease, herpangina and acute hemorrhagic conjunctivitis (AHC). Group B coxsackie viruses infect the pancreas, liver, heart and pleura which causes pericarditis, pleurodynia, myocarditis and hepatitis. Coxsackie viruses are transmitted through the fecal-oral route and respiratory aerosols. The viruses initially replicate in the upper respiratory tract and rest up to 3 weeks after initial infection. The viruses may also multiply in the sub mucosal lymph tissue and flown to the reticuloendothelial system. Further it act upon the target organs and leads to secondary viremia.

Incubation Period: 21 days

Prevention: Prevention is difficult; avoid direct contact with anyone with Coxsackie A disease, and their stool, saliva, and blister fluid. Washing hands frequently and cleaning of items handled by Coxsackie A diseased patients are the best practices.

Treatment: There is no specific treatment or vaccine available for coxsackie virus infections.