Cholera

Causes Of Cholera

Cholera is caused by a bacteria called Vibrio cholerae. There are approximately 200 strains of this bacteria. However, only two strains i.e O1 and O139 are known to be associated with cholera outbreaks. Both strains cause the same level of illness. 

Where are these bacteria found?

The bacteria are usually found in water that is contaminated with feces of an infected person. These bacteria are also found in the rivers that have saline water as they grow best in the presence of salt. 

What is the mode of transmission?

Cholera can be transferred from person to person by infected fecal matter entering the mouth or via water or food contaminated with Vibrio cholera bacteria.

What are the common sources of cholera infection in a community?

• Drinking water from sources such as unprotected wells, boreholes, and standpipes contaminated by feces during transportation or supply

• Food, drinks, and ice made from contaminated water

• Cooking and eating in utensils washed in contaminated water

• Food that is stored for a long period of time at room temperature

• Seafood especially crustaceans and shellfish grown in contaminated water

• Raw fruit and vegetables that are irrigated with water containing human waste or rinsed with contaminated water
  
  

Is cholera contagious?

Cholera usually does not spread through direct physical contact. However, during outbreaks, it becomes highly contagious. It can spread indirectly and directly due to widespread fecal contamination of food, water, and items like contaminated bedding, clothing, utensils etc.

What does bacteria do inside the body?

All individuals are not affected by the bacteria as the majority are killed by gastric acid. In case, bacteria survive, it forms colonies in the small intestine. These colonies produce cholera toxin which is responsible for most of the symptoms.

Symptoms Of Cholera

Cholera is asymptomatic in most of the individuals. However, even the asymptomatic individual can shed the bacteria into the environment through their feces for up to 10 days. 

The majority of individuals who develop symptoms often have mild to moderate manifestations. The incubation period (the period between exposure to an infection to the appearance of the first symptom) can range from 12 hours to 5 days. 

The classical symptom of cholera is massive and smelly diarrhea which is termed as “rice water stool”. The term is coined due to its similarity with the water in which rice is washed. 

The various signs and symptoms of cholera infection include:

• Acute watery diarrhea

• Fishy smell from stools

• Dehydration

• Vomiting

• Thirst

• Leg cramps

• Restlessness or irritability

• Muscle cramps

• Sleepiness and Tiredness

• Dry mouth

• Wrinkled skin

• Rapid deep breathing

• Rapid heart rate

• Fever (rarely seen and indicates some secondary infection)

• Hypoglycemia (mostly observed in children)

• Low blood pressure
  
  

Other signs and symptoms that may occur in severe cases, include the following:

• Sunken eyes

• Low or no urine output

• Skin pinch goes back very slowly

• Lethargic or unconscious

• Absent or weak pulse

• Respiratory distress

• Seizures

• Shock

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Risk Factors For Cholera

Several social, environmental, and biological risk factors can increase the risk of cholera. They are discussed as follows: 

1. Poor sanitation 

Lack of access to clean water and poor disposal facilities of feces increases the risk of cholera transmission. 

Approximately 97% of cholera cases are seen in countries having the lowest level of water and sanitation services in the year between  2010 to 2021. 

2. Open air defecation

Open-air defecation is associated with an increased risk of surface water contamination and hence more risk of waterborne diseases like cholera.

3. Source of water supply

People using improved (piped household, protected well or spring, or collected rainwater) water supply is at a lesser risk of contracting cholera.

4. Monsoon Season

The risk of contracting cholera is high during monsoons. This is because of the contamination of drinking water by sewage or polluted water bodies. 

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5. Improper hand hygiene

Avoiding handwashing with soap and water after toileting, before eating, and during handling food increases the risk of transmission of cholera bacteria. 

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6. Certain Medications

Cholera bacteria are not able to survive in the acidic environment of the stomach. So, individuals that are on any acid-neutralizing therapy such as proton pump inhibitors and antihistamines are at higher risk of infection. Such medications are also known to be associated to increase the severity of symptoms. 

7. Consuming Seafood

Individuals who consume raw or partially cooked seafood, crabs or shellfish, dried fish, and seafood salad have more chances of contracting cholera. 

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8. Bottle feeding

Studies suggest that bottle-fed infants and children are more prone to infection than ones breastfeeding. This is due to the lack of exposure to contaminated bottle feedings for breastfed infants. Breastfeeding also provides protective functions that boost immunity to fight infections. 

Most cases of cholera are seen in infants aged 6 to 11 months who are on their weaning journey. 

9. Achlorhydria

Individuals having a condition called achlorhydria – the absence of hydrochloric acid in digestive stomach juices are more prone to contracting cholera. This is because cholera bacteria grow rapidly in a low acidic environment.

10. Vitamin A deficiency

The deficiency of Vitamin A is also associated with an increased risk of cholera. 

11. Human immunodeficiency virus (HIV) infection

Studies suggest an increased risk of infection in people with HIV due to low immunity. 

12. Socioeconomic status

People with low incomes are more prone to cholera due to a lack of access to clean water. 

People are at high risk of cholera include:

• Healthcare personnel treating cholera patients

• Cholera response workers

• Travelers in an area of active cholera transmission 

Did you know?

There is a strong link between cholera and the human O blood group. The blood group O does not increase the risk of cholera but it impacts the severity of the disease. This association is proved by several previous outbreaks. In 1991 during an outbreak in Peru, the number of hospitalized patients was more with blood group O. Similarly, the Ganges delta has very less cases of cholera during outbreaks due to the low prevalence of people with blood group O.

Diagnosis Of Cholera

The diagnosis of cholera is important as it may turn into a widespread outbreak. It cannot be distinguished from any other infection-causing watery diarrhea without testing a stool sample. 

Stool culture

It is the most widely used method for the diagnosis of cholera. In this, stool samples are incubated with a solution that isolates the bacteria from it. The appearance of yellow clumps indicates cholera.
The exact strain of bacteria is identified through further testing. This confirmatory test is helpful in differentiating cholera from other bacterial, protozoa, or viral causes of dysentery. 

Darkfield microscopy

It involves an examination of stools under a dark field microscope. It is a rapid method. The vibrio-shaped cells with motility indicate cholera bacteria. 

Dipstick test

This test is often used in endemic areas. It involves placing a dipstick strip into a sample of stool. The two red lines on the dipstick confirm the presence of cholera. It takes between 2 and 15 minutes for the test to make a diagnosis.
The sensitivity and specificity of this test is not optimal. That is why, the fecal specimens should always be confirmed using culture-based methods. 

Prevention Of Cholera

Cholera is a preventable disease. There are several measures that can be taken at an individual and community level to prevent the outbreaks.

1. Preventing cholera at an individual level

Ensure safe drinking water 

• Drink only filtered or boiled water

• Use filtered or boiled water to prepare food, brush teeth, and make ice

• Avoid using water bottles without a seal

• Store water in a clean and covered container

Maintain hand hygiene

Cholera can be prevented by following basic hand hygiene. It is advised to thoroughly wash the hands with soap and water:

• After using the washroom

• Before, during and after preparing food

• Before and after eating food 

• Before and after feeding your children

• After changing your child’s diaper or washing their stools

• After taking care of someone suffering from cholera

Note: In case soap and water are not available (as in traveling), alcohol-based hand rub with at least 60% alcohol can be used. 

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Be cautious while using a washroom

• Use toilets to get rid of the feces instead of open defecation

• Dispose off the used diapers of children in toilet

• In case a toilet is not available, pee or poop at least 30 meters away from any body of water. 

Cook and consume food vigilantly

• Prepare food in filtered or boiled water

• Wash fruits and vegetables with filtered or boiled water

• Consume fruits and raw vegetables after peeling

• Cook food thoroughly especially seafood such as shellfish that has the maximum chances of contamination.

• Eat hot food

Maintain cleanliness

• Clean kitchen surfaces and utensils thoroughly with soap and water 

• Use kitchen utensils and surfaces to cook food after drying

• Wash clothes 30 meters away from drinking water sources

• Disinfect any stool contaminated surfaces with household bleach 
  
  

2. Preventing cholera at community level

A multifaceted community approach involving the following helps to mitigate the risk of cholera:

Implementing WaSH Services

Almost all cases of cholera arise due to poor access to safe drinking water and inadequate sanitation. WaSH is an acronym that stands for water, sanitation and hygiene. Availability of adequate and safe water and effective solid and liquid waste management plays a major role in decreasing the risk of contracting cholera. 

Promoting surveillance

Since cholera is a highly infectious disease, close monitoring of the cases by the government agencies at local level helps in preventing the outbreaks. It should be a part of a disease surveillance system that involves the sharing of information at global level. 
Any clinically suspected individual should be tested for cholera. Detection can be done using rapid diagnostic tests (RDTs) where positive cases indicate a cholera alert. It aids as a tool to control the cases by implementing the preventive strategies early. 

Engaging community

The local or central government should launch effective and engaging programmes with an aim to prevent cholera at mass scale. People and communities are a part of the process of developing and implementing strategies. 

The aim of the programmes are educating people about the:

• Basic hygiene measures such as handwashing with soap 

• Sanitation interventions such as safe disposal of feces of the children

• Safe preparation and handling of food

• Risk and symptoms of cholera

• Funeral practices for individuals who die from cholera to prevent infection among attendees.

Provision of Vaccination

The cholera vaccines are available in oral dosage form and denoted as oral cholera vaccine (OCV). The World Health Organisation (WHO) suggests using these vaccines in the cholera endemic areas. All three vaccines require two doses for full protection.

• Dukoral: This vaccine is given along with a buffer solution. It can be given to all the individuals that are over 2 years of age. The time duration between the two doses is 7 days to 6 weeks. This vaccine (2 doses) provides protection for 2 years. 

• Shancol and Euvichol: They have the same composition. Both of these vaccines are given without a buffer solution. Individuals over one year of age can take this vaccine. 

While, a two-dose OCV, has obtained license for use in India, mass vaccination covering the entire population in the country has not been implemented as of yet. This is due to factors like 

• Cholera has a tendency of localized outbreaks

• Mortality due to cholera has considerably reduced over time due to increasing use of oral rehydration salt solution

Specialist To Visit

Individuals should consult the doctor immediately in case of any symptoms of watery diarrhea or returning from any cholera-endemic country. 

The doctors that might help include:

• General physician

• Internal medicine specialist

• Gastroenterologist

• Pediatrician

A general physician will examine your symptoms and initiate treatment.

In case of severe cases, they may refer you to an Internal Medicine specialist who provides comprehensive care for adult patients, managing complex cases and addressing underlying health conditions.

Gastroenterologists can also be consulted as they have expertise in diagnosing and treating gastrointestinal disorders like cholera.

A pediatrician can be consulted for medical treatment and preventive healthcare services for children and adolescents.

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Treatment Of Cholera 

The success of cholera treatment depends upon the time to initiate the treatment. Prompt treatment reduces the risk of severe dehydration and its complications. 

The main aim of the therapy is to restore the hydration status of the patient, combat infection and support overall recovery.

1. Rehydration

• The goal of the therapy is to maintain normal hydration status by replacing ongoing losses. 
• Immediate administration of oral rehydration solution (ORS) is recommended.
• Make ORS in sterile water (previously boiled or chlorine treated)
• ORS should be taken sip by sip frequently 

Interesting fact!

The approximate amount of ORS (in milliliters) needed over 4 hours can also be calculated by multiplying the patient’s weight in kg by 75.

• In case ORS is not available, drink water, broth, and/or other fluids
• Avoid taking sugary drinks such as juice, soft drinks, or sports drinks as they could worsen diarrhea
• ResoMal should be given instead of ORS in severely malnourished people
• Breastfeeding should be encouraged for infants

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2. Intravenous (I.V). Fluids

• The severely dehydrated individuals (fluid loss greater than 10% of body weight) are prone to shock. 
• Such patients need rapid administration of intravenous fluids to compensate the fluid loss.
  
  

3. Antibiotics

• Antibiotics therapy is initiated once an appropriate volume status has been achieved.
• They are known to reduce the duration and severity of diarrhea. The use of antibiotics is associated with reducing the volume of stool by 50%.
• Studies also suggest that antibiotics reduce the duration of shedding of bacteria in stool. 

The common examples of antibiotics used are

• Tetracycline 
• Doxycycline

In case of antibiotic resistance, the following antibiotics may be prescribed

• Ciprofloxacin
• Azithromycin 
• Erythromycin

The antibiotic therapy is usually given for about 3-5 days.

Note: Tetracycline is not recommended in pregnant women and children under 5 years of age because it causes permanent discolouration of teeth.

In cholera, zinc deficiency can lead to reduced water and electrolyte absorption. Therefore, zinc plays an important role in recovery from the symptoms. Zinc combined with ORS reduces the duration, severity, and recurrences of episodes of diarrhea. 

5. Nutritional interventions

It includes taking a high-energy diet immediately after initial restoration of fluids. It helps in preventing malnutrition and several other complications such as hypokalemia (reduced level of potassium) and hypoglycemia (low blood glucose).

Complications Of Cholera 

Most of the complications develop due to severe volume depletion in the body. The fluid loss can reach up to 1 liter per hour in adults and 20 ml/kg/hr in children. This can lead to complications like:

• Hypovolemic shock

• Metabolic acidosis (build up of acid in the body due to imbalance in the acid base balance as a result of electrolyte loss)

• Hypotension (low blood pressure)

• Hypoglycemia (low blood glucose)

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In rare cases, the severe hypotension can even lead to:

• Stroke

• Kidney dysfunction

Persistent vomiting can lead to aspiration pneumonia (condition in which food or liquid is breathed into the airways of lungs, instead of being swallowed)