Communicable diseases
Subtopic:
Cholera
Cholera is an acute diarrheal illness caused by infection of the small intestine with the bacterium Vibrio cholerae.
This serious infection is characterized by the rapid onset of profuse, watery diarrhea, often described as “rice water” stool, accompanied by vomiting. This leads to rapid and severe dehydration, electrolyte imbalances, and potentially life-threatening circulatory collapse and acidosis if left untreated. Cholera is an internationally notifiable disease, highlighting its potential for global spread and the need for immediate public health response.
Causative Agent: Vibrio cholerae
The bacterium responsible for cholera is Vibrio cholerae, a comma-shaped, Gram-negative organism. Key characteristics include:
Morphology and Staining: Possesses a curved, rod-like shape and stains pink with Gram staining (Gram-negative).
Metabolism and Growth: It is a facultatively anaerobic bacterium, capable of growth with or without oxygen. It thrives in alkaline environments (optimal pH around 8.0) and prefers temperatures between 30-40°C, outside of which its growth is inhibited.
Motility and Adhesion: Vibrio cholerae is highly motile due to the presence of a single polar flagellum, enabling movement. It also possesses pili (fimbriae), hair-like appendages that facilitate attachment to the lining of the small intestine.
Transmission Pathways
Cholera spreads primarily through the fecal-oral route, with several key mechanisms:
Contaminated Water: The most significant source of transmission is drinking water contaminated with the feces of infected individuals.
Contaminated Food: Ingesting food, particularly raw or undercooked seafood and produce, that has come into contact with contaminated water or been handled by infected individuals.
Direct Person-to-Person Contact: While less common, direct contact with the feces of an infected person, especially in environments with poor sanitation and hygiene, can lead to transmission.
Asymptomatic Carriers: Individuals infected with Vibrio cholerae may not exhibit symptoms but can still shed the bacteria in their feces, contributing to the spread.
Factors Influencing Susceptibility
Several factors can increase an individual’s likelihood of contracting cholera or experiencing a more severe infection:
Infectious Dose: A relatively high number of bacteria (typically estimated at 100 million for healthy adults with normal stomach acidity) must be ingested to establish infection. This underscores the importance of the concentration of bacteria in contaminated sources.
Age: Young children, especially those between two and four years old, are more susceptible due to potentially less developed immune systems and increased exposure through play and hygiene practices.
Compromised Immunity: Individuals with weakened immune systems, such as those living with HIV/AIDS, malnutrition, or other immunocompromising conditions, are at a significantly higher risk of severe disease.
Reduced Gastric Acidity: Conditions or medications that reduce stomach acid (e.g., antacids, proton pump inhibitors) can decrease the body’s natural defense against ingested bacteria, increasing susceptibility.
Pathogenesis: How Cholera Develops
The pathogenesis of cholera involves a series of steps within the small intestine:
Colonization: Vibrio cholerae bacteria that survive the acidic environment of the stomach reach the small intestine. Their flagella aid in navigating the mucus layer, and pili facilitate adherence to the intestinal epithelial cells. The bacteria then multiply rapidly on the intestinal surface.
Enterotoxin Production: Once established, Vibrio cholerae produces a potent enterotoxin called cholera toxin (CT). This toxin does not invade the intestinal cells or enter the bloodstream directly but exerts its effects on the surface of the epithelial cells.
Disruption of Cellular Function: CT binds to specific receptors on the intestinal epithelial cells, triggering a cascade of intracellular events. This leads to the activation of an enzyme called adenylate cyclase, which increases the levels of cyclic adenosine monophosphate (cAMP) within the cells.
Massive Fluid and Electrolyte Secretion: Elevated cAMP levels disrupt the normal transport of ions across the cell membrane. This results in a massive outflow of chloride ions and inhibits the absorption of sodium ions. Water follows these electrolytes into the intestinal lumen due to osmosis.
Profuse Watery Diarrhea: The excessive secretion of fluids and electrolytes into the small intestine overwhelms the absorptive capacity of the colon, resulting in the characteristic profuse, watery diarrhea.
Dehydration and Electrolyte Imbalance: The rapid and substantial loss of fluids and electrolytes (sodium, potassium, bicarbonate) leads to severe dehydration. The body attempts to compensate, drawing fluid from various tissues.
Consequences of Dehydration: Dehydration manifests as:
Dry mucous membranes: Including the mouth, tongue, and eyes.
Decreased skin turgor: The skin loses its elasticity and appears wrinkled.
Hypovolemia: Reduced blood volume leading to a rapid, weak pulse and low blood pressure.
Muscle cramps: Due to electrolyte imbalances.
Metabolic acidosis: Loss of bicarbonate leads to an increase in blood acidity.
Organ dysfunction: Severe dehydration can lead to kidney failure, lung failure, and ultimately, multi-organ failure.
Clinical Manifestations: Signs and Symptoms
The incubation period for cholera is typically short, ranging from a few hours to 2-3 days. The clinical presentation progresses through distinct stages:
Diarrheal Stage (Onset): This initial phase lasts for 3-12 hours and is marked by the abrupt onset of:
Profuse watery diarrhea: Characterized by high volumes of “rice water” stool, a thin, milky white fluid that may contain mucus.
Vomiting: Frequent vomiting contributes significantly to fluid and electrolyte loss.
Muscle cramps: Often experienced in the legs and abdomen due to electrolyte imbalances.
Mild dehydration: May be present initially but can rapidly worsen.
Collapse Stage (Rapid Dehydration): Developing within 6-12 hours, this stage is characterized by:
Worsening diarrhea and vomiting: Leading to rapid and severe fluid depletion.
Intense thirst and weakness: As the body becomes increasingly dehydrated.
Sunken eyes and dry mucous membranes: Visible signs of fluid loss.
Decreased skin turgor and elasticity: The skin loses its ability to return to its normal shape after being pinched.
Hypovolemia: Manifesting as a rapid heartbeat (tachycardia), weak pulse, and low blood pressure (hypotension).
Rapid breathing (tachypnea): The body attempts to compensate for metabolic acidosis.
Electrolyte imbalances: Potassium loss can lead to cardiac arrhythmias.
Acidosis: The buildup of acid in the blood contributes to rapid breathing and lethargy.
Hypoxia: Reduced oxygen delivery to tissues due to decreased blood volume.
Shock Stage (Life-Threatening): This critical stage requires immediate intervention and involves:
Circulatory collapse: Severe dehydration leads to inadequate blood flow to vital organs.
Rapid and weak pulse: The heart struggles to maintain circulation.
Significantly low blood pressure: Often difficult to measure.
Altered mental status: Confusion, lethargy, and potentially coma.
Kidney failure: Reduced blood flow to the kidneys impairs their function.
Respiratory failure: Severe dehydration can compromise lung function.
Diagnosis
Diagnosis of cholera involves a combination of clinical assessment and laboratory testing:
Clinical History: Evaluating the patient’s travel history to endemic areas, exposure to potential sources of contamination, and characteristic symptoms (profuse watery diarrhea).
Physical Examination: Assessing for signs of dehydration, including dry mucous membranes, sunken eyes, decreased skin turgor, and vital signs (heart rate, blood pressure).
Laboratory Tests:
Stool Culture: The gold standard for diagnosis. Stool samples are cultured on selective media to identify Vibrio cholerae.
Rapid Diagnostic Tests (RDTs): Immunochromatographic tests that can detect Vibrio cholerae O1 or O139 antigens in stool samples, providing quicker results for initial screening.
Polymerase Chain Reaction (PCR): Molecular tests that detect the genetic material of Vibrio cholerae in stool samples, offering high sensitivity and specificity.
Prevention
Preventing cholera relies on interrupting the fecal-oral route of transmission through comprehensive public health measures and individual precautions:
Preventing cholera involves a multi-faceted approach focused on hygiene, sanitation, and vaccination. Key steps include:
Hand Hygiene: Thoroughly wash hands with soap and water for at least 20 seconds:
Before preparing, serving, or consuming food.
After using the latrine or toilet.
Safe Drinking Water: Ensure drinking water is safe by:
Boiling water for at least one minute.
Treating water with appropriate chlorine solutions or purification tablets.
Storing treated water in clean, covered containers to prevent recontamination.
Food Safety: Practice safe food handling:
Consume food while it is still hot.
Wash raw fruits and vegetables thoroughly with safe water; peeling them when possible is recommended.
Food Storage: Protect food from contamination by:
Covering all food to prevent contact with dust, flies, and cockroaches.
Reporting and Burial Practices: In the event of a cholera-related death:
Report the death immediately to health authorities.
Ensure prompt and safe burial practices.
Avoid serving food during funeral gatherings to minimize potential spread.
Surveillance and Reporting:
Implement active surveillance systems to detect potential cases early.
Report suspected cholera cases promptly to facilitate rapid containment efforts.
Disinfection: Effectively kill cholera germs by:
Sprinkling germicidal solutions (e.g., containing sodium hypochlorite) on stool or vomitus.
Disinfecting materials used by infected individuals.
Water and Sanitation Improvement: Enhance public health infrastructure by:
Improving access to clean and safe water sources.
Implementing and maintaining proper waste management and sanitation systems.
Outbreak Investigations:
Conduct thorough investigations of diarrheal outbreaks to identify the source of contamination.
Implement appropriate control measures based on the investigation findings.
Cholera Vaccination:
Consider immunization with oral cholera vaccines (OCV), especially in areas prone to outbreaks or for individuals at high risk.
Treatment of Malnutrition:
Address malnutrition as individuals with weakened immune systems are more susceptible to severe cholera.
Provide adequate nutrition to improve overall health and resilience.
Management and Treatment of Cholera
Cholera is a medical emergency requiring prompt and effective treatment. The primary goals are to restore fluid and electrolyte balance and prevent the spread of infection.
Patient Admission:
Admit patients to designated facilities (temporary hospitals, isolation wards).
Utilize cholera beds with a central hole and a calibrated bucket containing disinfectant placed underneath to collect and measure stool output.
Oral Rehydration Solution (ORS):
ORS is the cornerstone of cholera treatment, crucial for rehydrating patients and replacing lost electrolytes.
Administer ORS orally as the primary method of rehydration.
In cases of severe dehydration, supplement with intravenous fluids (Ringer’s lactate or normal saline) alongside ORS.
Reassess the patient’s hydration status every one to two hours and continue fluid replacement as needed.
If hydration does not improve, increase the intravenous fluid administration rate.
During the first 24 hours, patients may require 200 ml/kg or more of fluid.
Once hydration improves and the patient can drink, transition to ORS alone.
Nasogastric Tube:
In young children unable to drink adequately, a nasogastric tube can be used to administer fluids.
Antibiotics:
Antibiotics can help reduce the duration and severity of illness in certain cases.
Commonly used antibiotics include:
Doxycycline (300mg single dose, contraindicated in pregnancy).
Ciprofloxacin (1g single dose, contraindicated in pregnancy).
For pregnant women: Septrin (trimethoprim/sulfamethoxazole).
For children: Cotrimoxazole, doxycycline, ciprofloxacin, or erythromycin may be considered based on local guidelines and resistance patterns.
Hypoglycemia Management:
If the patient presents with hypoglycemia (low blood sugar), administer intravenous dextrose to correct the levels.
Zinc Supplementation:
Zinc supplementation is beneficial in treating and preventing diarrhea, particularly in children.
Isolation and Infection Control:
Isolate patients to prevent the spread of the highly infectious bacteria found in stool and vomit.
Ensure proper disposal of stools and vomit, ideally into a pit latrine or a designated disinfection system.
Equipment and Instrument Disinfection:
Clean hospital equipment with appropriate disinfectants (e.g., sodium hypochlorite).
Sterilize instruments to prevent transmission.
Fluid Balance Chart:
Maintain a detailed fluid balance chart to closely monitor the patient’s hydration status, including intake and output.
Cholera Management: Aims and Actions
Aims of Cholera Management:
Immediate Reduction of Electrolyte and Fluid Loss: The top priority to ensure patient survival.
Prevention of Infection Spread: Implementing strict isolation measures within healthcare facilities and the community.
Notification of Authorities: Promptly informing public health authorities about the outbreak.
Elimination of Bacteria: Utilizing antibiotics to reduce the bacterial load and shorten illness duration.
Patient and Public Education: Raising awareness about cholera transmission, prevention, and management.
Actions in Cholera Management:
First Aid:
Reception: Healthcare personnel, wearing proper protection, assess the patient’s airway, breathing, circulation (ABCs), dehydration signs (sunken eyes, dry mucous membranes, skin turgor), level of consciousness, and vital signs.
Immediate IV Line: Establish an intravenous line and begin fluid replacement with Ringer’s Lactate (R/L), Dextrose 5%, or Normal Saline, adjusting the rate based on the severity of dehydration.
Positioning and Oxygen: Place the patient in a comfortable position and provide oxygen therapy if needed.
Hygiene: Ensure patient hygiene, including clean clothes, skin, and perineum.
History Taking: Gather a detailed history of the illness, including duration and severity of diarrhea and vomiting, level of consciousness, vital signs, and relevant medical information.
Doctor’s Orders: Follow the doctor’s orders meticulously.
Treatment of Shock: Administer intravenous fluids as prescribed (e.g., rapid bolus of 100ml/kg over 30 minutes, followed by 70ml/kg over 2.5 hours), and reassess the patient’s response frequently. Increase fluid administration if there is no improvement.
Oxygen Therapy: Provide supplemental oxygen as needed.
Admission:
Isolation: Isolate the patient in a designated cholera bed with appropriate waste disposal mechanisms.
Personal Protective Equipment (PPE): Healthcare personnel must wear appropriate PPE (aprons, masks, isolation gowns, caps, gumboots, disposable gloves) and explain the rationale to the patient.
District Health Authority: Inform the district health authority about the case for public health action.
Drugs:
Administer appropriate antibiotics as prescribed by a physician (examples provided previously).
Frequent Assessment:
Vital Signs: Monitor vital signs frequently (initially every 15 minutes, then gradually less often as the patient stabilizes).
Dehydration Signs: Assess dehydration signs regularly (every 30 minutes) and adjust treatment accordingly.
Level of Consciousness: Observe the patient’s level of consciousness for any changes.
Fluid Output: Measure and record the volume, frequency, consistency, and characteristics of diarrhea and vomiting.
Other Immediate Care:
Infection Control:
Disinfect all stool and vomitus with 1% sodium hypochlorite (JIK) before disposal.
Thoroughly clean and disinfect bedpans, buckets, urinals, and other contaminated items.
Maintain patient hygiene (skin, mouth, perineum).
Soak contaminated linen in disinfectant, wash thoroughly, and handle with care.
Dispose of excreta and food remains safely after measurement.
Ensure proper cleaning and disinfection of utensils.
Provide safe, boiled, and treated water.
Ensure proper food preparation practices.
Maintain environmental hygiene by cleaning and disinfecting patient rooms and equipment.
Minimize direct contact with patient’s waste.
Diet:
Parenteral Nutrition: Provide intravenous or nasogastric tube feeding in severe cases.
Fluid Diet: Start with a fluid diet to rehydrate the patient.
Light Diet: Gradually transition to a light, nourishing, well-balanced, non-irritating diet.
Normal Diet: Progress to a normal diet once the patient is stable.
Rehabilitation/Physiotherapy:
Passive ROM: Initiate passive range of motion exercises while the patient is bedridden.
Active ROM: Encourage active movement, starting with sitting up in bed and progressing to walking.
Reassurance: Provide continuous reassurance to the patient.
Health Teaching: Educate the patient about cholera, its causes, transmission, prevention, hygiene practices, food and water safety, vector control, reporting new cases, and limiting shared equipment.
Discharge:
Provide the patient with comprehensive discharge information and follow-up appointment details.
Advise the patient on maintaining adequate fluid intake, good nutrition, and consuming only safe food and water.
Complications of Cholera
Untreated or severe cholera can lead to serious complications:
Severe Dehydration and Vascular Collapse: Leading to circulatory shock and potential death.
Electrolyte Imbalance and Acidosis: Disrupting bodily functions and potentially causing organ damage.
Shock: A life-threatening condition due to insufficient blood flow.
Organ Failure: Affecting the heart, kidneys, liver, and lungs.
Hypoxia and Brain Malnutrition: Leading to seizures, coma, and death.
Gangrene: Due to severely reduced blood flow to extremities.
Hypostatic Pneumonia: In bedridden patients due to reduced lung capacity.
Tetany: Muscle spasms and seizures due to electrolyte imbalances.
Abortion and Intrauterine Fetal Death: In pregnant women due to increased intra-abdominal pressure.
Related Question
a) List 5 cardinal signs and symptoms of cholera.
b) Outline 10 specific nursing care in an outbreak of cholera.
Solutions
a) Five cardinal signs and symptoms of cholera include:
1. Watery diarrhea, sometimes in large volumes.
2. Nausea and vomiting.
3. Dehydration.
4. Rice-water stools.
5. Loss of skin elasticity.
b) Ten specific nursing care measures in an outbreak of cholera:
1. Wash hands with soap and running water frequently, especially after using the toilet and before handling food.
2. Advise people to drink only safe water, such as bottled water or water that has been boiled.
3. Encourage individuals to consume food that is fully cooked and hot, and to avoid street vendor food whenever
possible.
4. Discourage the consumption of sushi, as well as raw or improperly cooked fish and seafood.
5. Monitor intake and output, taking note of the number, character, and amount of stools.
6. Promote the use of latrines or proper disposal of feces, emphasizing not to defecate in any body of water.
7. Ensure that any articles used are properly disinfected or sterilized before use.
8. Maintain strict asepsis during dressing changes, wound care, intravenous therapy, and catheter handling.
9. Practice hand hygiene by washing hands or using hand sanitizer before and after having contact with the
patient.
10. Implement proper waste management procedures, particularly for human excreta