Cholera

Cholera is asymptomatic in most individuals. However, even asymptomatic individuals 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 and the appearance of the first symptom) can range from 12 hours to 5 days.

The classical symptom of cholera is massive, smelly diarrhea, referred to as “rice water stool,” due to its similarity to 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:

• Sunken eyes
• Low or no urine output
• Skin pinch goes back very slowly
• Lethargy or unconsciousness
• Absent or weak pulse
• Respiratory distress
• Seizures
• Shock

Here are some tips that help prevent dehydration in diarrhea!

Cholera is caused by a bacteria called Vibrio cholerae. There are approximately 200 strains of this bacteria; however, only two strains, 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 the feces of an infected person.
• These bacteria are also found in rivers with 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 fruits 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, and utensils.

What does bacteria do inside the body?

Not all individuals are affected by the bacteria, as the majority are killed by gastric acid. In cases where bacteria survive, they form colonies in the small intestine. These colonies produce cholera toxin, which is responsible for most of the symptoms.

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

• Poor sanitation: Lack of access to clean water and inadequate disposal facilities for feces increase the risk of cholera transmission. Approximately 97% of cholera cases are reported in countries with the lowest levels of water and sanitation services from 2010 to 2021.
• Open air defecation: Open-air defecation is associated with an increased risk of surface water contamination, leading to a higher risk of waterborne diseases like cholera.
• Source of water supply: Individuals using improved water sources (such as piped household water, protected wells or springs, or collected rainwater) have a lower risk of contracting cholera.
• Monsoon season: The risk of contracting cholera is heightened during monsoons due to the contamination of drinking water by sewage or polluted water bodies.
• Improper hand hygiene: Failing to wash hands with soap and water after using the toilet, before eating, and while handling food increases the risk of cholera bacteria transmission.
• Certain medications: Cholera bacteria are unable to survive in the acidic environment of the stomach. Therefore, individuals on acid-neutralizing therapies such as proton pump inhibitors and antihistamines are at a higher risk of infection. These medications may also be associated with increased severity of symptoms.
• Consuming seafood: Individuals who consume raw or partially cooked seafood, crabs, shellfish, dried fish, and seafood salads are at a greater risk of contracting cholera.
• Bottle feeding: Studies indicate that bottle-fed infants and children are more susceptible to infection compared to breastfed infants. This is due to the lack of exposure to contaminated bottle feedings for breastfed infants, who also receive protective functions that boost immunity against infections. Most cholera cases occur in infants aged 6 to 11 months who are in the weaning phase.
• Achlorhydria: Individuals with achlorhydria, a condition characterized by the absence of hydrochloric acid in digestive juices, are more prone to contracting cholera due to the rapid growth of cholera bacteria in a low-acidic environment.
• Vitamin A deficiency: Deficiency of Vitamin A is associated with an increased risk of cholera.
• Human immunodeficiency virus (HIV) infection: Studies suggest that individuals with HIV are at an increased risk of cholera infection due to compromised immunity.
• Socioeconomic status: Individuals with low incomes are more susceptible to cholera due to a lack of access to clean water.

People at high risk of cholera include:

• Healthcare personnel treating cholera patients
• Cholera response workers
• Travelers in areas of active cholera transmission

Did you know? There is a strong link between cholera and the human O blood group. While blood group O does not increase the risk of cholera, it affects the severity of the disease. This association has been demonstrated in several previous outbreaks. For instance, during the 1991 outbreak in Peru, a higher number of hospitalized patients belonged to blood group O. Conversely, the Ganges delta experienced fewer cholera cases during outbreaks due to the low prevalence of individuals with blood group O.

The diagnosis of cholera is crucial as it may lead to a widespread outbreak. It cannot be distinguished from other infections causing watery diarrhea without testing a stool sample.

Stool Culture
This is the most widely used method for diagnosing cholera. Stool samples are incubated with a solution that isolates the bacteria. The appearance of yellow clumps indicates the presence of cholera. Further testing identifies the exact strain of bacteria, which is helpful in differentiating cholera from other bacterial, protozoal, or viral causes of dysentery.

Darkfield Microscopy
This method involves examining stools under a dark field microscope. It is a rapid technique. The presence of vibrio-shaped cells with motility indicates cholera bacteria.

Dipstick Test
This test is often used in endemic areas. It involves placing a dipstick strip into a stool sample. The appearance of two red lines on the dipstick confirms the presence of cholera. Diagnosis takes between 2 and 15 minutes. However, the sensitivity and specificity of this test are not optimal; therefore, fecal specimens should always be confirmed using culture-based methods.

Cholera is a preventable disease. There are several measures that can be taken at an individual and community level to prevent 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 hands with soap and water:
• After using the washroom.
• Before, during, and after preparing food.
• Before and after eating food.
• Before and after feeding children.
• After changing a 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.
• Be cautious while using a washroom:
• Use toilets to dispose of feces instead of open defecation.
• Dispose of used diapers in the toilet.
• If a toilet is not available, urinate or defecate 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 highest 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 at least 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 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 cases by government agencies at the local level helps in preventing outbreaks. It should be part of a disease surveillance system that involves sharing information at the 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. This aids in controlling cases by implementing preventive strategies early.

• Engaging the community:

The local or central government should launch effective and engaging programs aimed at preventing cholera on a mass scale. People and communities are part of the process of developing and implementing strategies. The aim of the programs is to educate people about:

• Basic hygiene measures such as handwashing with soap.
• Sanitation interventions such as safe disposal of children’s feces.
• 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, denoted as oral cholera vaccine (OCV). The World Health Organization (WHO) suggests using these vaccines in 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 individuals 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 and are given without a buffer solution. Individuals over one year of age can take this vaccine.

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

• Cholera has a tendency for localized outbreaks.
• Mortality due to cholera has considerably reduced over time due to the increasing use of oral rehydration salt solution.

The success of cholera treatment depends on the timely initiation of therapy. 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 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 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 individuals.
• Breastfeeding should be encouraged for infants.

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2. Intravenous (I.V.) Fluids

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 for fluid loss.

3. Antibiotics

Antibiotic therapy is initiated once an appropriate volume status has been achieved.

Antibiotics are known to reduce the duration and severity of diarrhea, and their use is associated with a 50% reduction in stool volume.

Studies also suggest that antibiotics reduce the duration of bacterial shedding in stool.

The common examples of antibiotics used are:

• Tetracycline
• Doxycycline

In cases of antibiotic resistance, the following antibiotics may be prescribed:

• Ciprofloxacin
• Azithromycin
• Erythromycin

Antibiotic therapy is usually given for about 3-5 days.

Note: Tetracycline is not recommended for pregnant women and children under 5 years of age due to the risk of permanent discoloration of teeth.

4. Zinc

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

5. Nutritional Interventions

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

Most 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 such as:

• Hypovolemic shock
• Metabolic acidosis (buildup of acid in the body due to an imbalance in the acid-base balance as a result of electrolyte loss)
• Hypotension (low blood pressure)
• Hypoglycemia (low blood glucose)

In rare cases, severe hypotension can even lead to:

• Stroke
• Kidney dysfunction

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

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