Cholera

Causes

Cholera is caused by the short, rod-shaped, gram-negative bacterium called Vibrio cholera of O1 or O139 serogroups. The pathogenic Vibrio cholera of O1 or O139 serogroups produce an enterotoxin which affects the intestinal cells. Usually the incubation period is 12-28 hours and in case of V. cholera O1 the incubation period ranges from 12 hours to 5 days.

Risk Factors

Ø Lacking of hygienic water supplies and poor sewage disposal. Ø Cholera cannot survive in acidic conditions, so acids in the stomach serves as a defence against infection. But, in individuals with decreased stomach acids i.e, children, elderly population, individuals on H2 blockers (famotidine, ranitidine etc.) and proton-pump inhibitors (PPIs) like pantoprazole, esmoprazole, lansoprazole, omeprazole, rabeprazole etc are at greater risk for cholera infection. Ø Individuals with type O blood group are twice at risk to develop cholera when compared to other blood groups. Ø Individual who consumes raw or under-cooked food like shell, fish and crab which are caught is waters polluted with sewage. Ø Vegetables grown with polluted water containing human wastes. Ø When a person is infected with cholera, the people living along with them and around them are at higher risk to develop cholera. Transmission Ø Generally cholera bacteria is passed through the stools. An individual can be infected with cholera either by drinking water or eating food that is contaminated by the bacteria. Ø The source of contamination is usually when feces (stool) of an infected individual contaminates the food and water. Ø Bacteria usually attaches themselves to the chitin containing shells of crabs, shrimps, and other shell fish which could be the source of infection in the humans, when an individual consumes raw or under-cooked food.

Symptoms

Cholera is an acute infection of the small intestine which presents with extreme watery diarrhoea and causes rapid and extreme loss of water and salts. severe depletion of salts and body fluids. Individuals could be asymptomatic or symptomatic. Asymptomatic individuals generally have diarrhoea for a few days whereas, among the symptomatic individuals the duration is 2 days to 2 weeks and very rarely to a longer duration. Once the bacterium enters into the intestines and infects the intestines by producing enterotoxin from its surface of the the coating. This enterotoxin goes and binds to the cells lining the small intestine and enters into the cells and controls the movement of water and electrolytes between the intestines and the circulatory system. Thereby switch on the pumps and causes huge amounts(up-to 1 litre per hour) of fluids to move into intestinal tract. Thereby causes severe depletion of salts and water from the body. The symptoms of cholera will be present for about 2 - 7 days and includes the following: Ø Extreme watery diarrhoea with specks of mucus so, often it is called as “rice water stools” Ø Fever, weakness, muscle cramps Ø Diarrhoea, often associated with vomiting which leads to severe dehydration Ø Thirsty, dry toungue Ø Eyes become hallow and sunken Ø Low blood pressure Ø Loss of serum electrolytes Ø The skin on the hands appears like of those whose hands are immersed in fluid for long duration which is referred to as “washerwoman hands” Ø Children may also have seizures in case of severe dehydration. Ø Enormous amounts of watery diarrhoea I.e. up-to 1 liter per hour leads to hypotensive shock and death within few hours after the onset of symptom, this is known as “cholera gravis”. Ø Complications of cholera include kidney failure, stroke, shock, coma and death if untreated.

Diagnosis

Most cases of cholera are diagnosed based proper history taking and physical examination on the clinical presentation when an individual presents with acute watery diarrhoea. However, watery diarrhoea could be present in various other conditions. So, the diagnosis can be confirmed by performing a few tests like stool cultures which is the considered as the gold standard for the laboratory diagnosis as it helps in isolating the organism, but this method is time-taking, few biochemical tests and PCR methods like stool bio-fire GI panel helps in early and rapid detection of cases of cholera.

Treatments

The treatment of cholera mainly focuses on to replenish the depleted salts and fluids. In treating cholera, it is crucial to replace the lost salts and fluids with oral re-hydration therapy(ORS) and intravenous alkaline solution of sodium chloride Treatment differs based upon the effected individual i.e. adults, pregnant women and children. Treatment with antibiotics like tetracycline's, fluoroquinolones or macrolides is advised in severe cases of cholera which reduces the duration of illness and also reduces the requirement of fluids to a certain extent. In children (6months and older), supplements like zinc of about 20mg a day and vitamin A supplementation would be helpful in reducing the severity and duration of the illness. Nutritional interventions like high energy diet is recommended to prevent malnutrition else would lead to complications like hypokalemia (decreased potassium levels) and hypoglycemia (decreased blood sugar levels).

Preventive Measures

Ø Maintaining good hand hygiene practices like hand-washing with soap and water, especially after using the toilet for about 15 seconds and before handling food would be helpful in preventing the infection. Ø Drinking boiled water and water from sealed water bottles would be helpful in prevention of acquiring the infection. Ø Always eat fresh fruits which are peeled by yourself and vegetables that are peeled and boiled at high temperatures. Ø Avoid eating raw and under-cooked sea food in order to prevent the infection. Ø Dukoral, Shancol and Euvichol oral vaccines are available in India which could protect against cholera for about 2 years and 3 years respectively. Dukoral can be given to all the individuals greater than 2 years of age. Immunization schedule contains a minimum interval of 7 days and no more than 6 weeks delay between each dose. Children between 2 to 5 years of age may require third dose in case of Dukoral and it is mainly used for travellers. Two doses of this vaccine would provide protection against cholera for 2 years. Ø Shancol and Euvichol should be given as two doses, given with a minimum interval of 2 weeks. Two doses of these vaccines would protect against cholera for 3 years.

Do's & Don’t's

Do’s Always maintain good hand hygiene Drink boiled tap water and in case of travelling always opt for water from sealed water bottles. Eat fresh fruits which are peeled by yourself Always eat cooked seafood. Don’t s Avoid eating raw and under-cooked sea food Avoid food by the street vendors and unhygienic places.

If you exhibit sudden onset of severe watery diarrhea and have a history of travel to cholera-endemic areas, seek immediate consultation with an Infectious Disease specialist in the Internal Medicine department to address potential Cholera infection.