Typhoid Fever (Enteric Fever)

Typhoid fever is an acute, life-threatening systemic bacterial infection characterized by prolonged fever and is primarily spread through the fecal-oral route via contaminated food and water. The term "Enteric Fever" collectively refers to both typhoid and paratyphoid fevers.

• Primary Cause: Salmonella enterica serotype Typhi (commonly referred to as Salmonella typhi).
• Secondary Causes (Paratyphoid): Salmonella paratyphi A, B, and C (which usually cause a milder illness with a similar clinical picture).

Typhoid fever is contracted by the ingestion of the bacteria in contaminated food or water. The spread is classically summarized by the "5 Fs": Feces, Fingers, Food, Fomites, and Flies.

• Contaminated Water/Food: Patients with acute illness shed the bacteria in their stool and urine, containing a high concentration of the pathogen. If sewage contaminates the surrounding water supply, or if infected food handlers do not wash their hands, the bacteria spread rapidly.
• Environmental Survival: The bacteria are highly resilient and can survive for weeks in water, ice, dust, or dried sewage.
• The Chronic Carrier State: About 3-5% of patients become chronic carriers of the bacteria after the acute illness resolves.
  • Some patients suffer a very mild illness that goes completely unrecognized, yet they become long-term carriers.
  • The bacteria persistently multiply in the gallbladder, bile ducts, or liver and pass continuously or intermittently into the bowel and out in the stool.
  • These chronic carriers may have absolutely no symptoms but can be the source of new outbreaks of typhoid fever for many years.

Understanding how Salmonella typhi behaves inside the body is crucial to understanding the timeline of symptoms and the appearance of complications. It is a highly specialized intracellular pathogen.

1. Ingestion and Gastric Survival: The bacteria are ingested via contaminated food/water. They must survive the highly acidic environment of the stomach. (Patients on antacids or with low stomach acid are at higher risk of infection with a lower bacterial dose).
2. Intestinal Invasion (Peyer's Patches): The bacteria reach the distal end of the small intestine (the terminal ileum). Here, they attach to and invade specialized immune tissues called Peyer's patches (specifically via M cells).
3. Intracellular Survival: Once they cross the intestinal lining, they are engulfed by macrophages (immune cells). However, instead of being destroyed, S. typhi survives and multiplies inside these macrophages.
4. Primary Bacteremia (Incubation Period): The infected macrophages travel through the lymphatic system to the mesenteric lymph nodes, and then enter the bloodstream. This brief, asymptomatic spread is the primary bacteremia.
5. Reticuloendothelial System (RES) Multiplication: The bacteria are carried to organs rich in macrophages: the liver, spleen, bone marrow, and gallbladder. Here, they multiply massively over 1 to 3 weeks (the incubation period).
6. Secondary Bacteremia (Onset of Symptoms): Once critical mass is reached, large numbers of bacteria burst from these organs back into the bloodstream. This triggers the onset of clinical symptoms (fever, headache, malaise) characterizing the First Week of illness.
7. Re-invasion of the Bowel: From the infected gallbladder, bacteria are dumped into the bile and back into the intestine in massive numbers. This causes severe secondary inflammation of the Peyer's patches, leading to necrosis (tissue death), sloughing, and ulceration by the Third Week.

Classically, the course of untreated typhoid fever is divided into four distinct stages, each lasting approximately one week. Modern early antibiotic treatment often halts this progression, but understanding the natural course is essential for recognizing delayed presentations.

The secondary bacteremia begins. The Peyer's patches of the distal ileum are invaded by the bacillus and become inflamed.

• Step-Ladder Fever: A gradual, daily rise in temperature, dropping slightly in the morning but peaking higher each successive evening (resembling a step-ladder).
• Relative Bradycardia (Faget's Sign): Normally, heart rate rises with a high fever. In typhoid, the pulse is unexpectedly slow relative to the high temperature.
• Constitutional Symptoms: Severe persistent frontal headache, general malaise, generalized body aching, anorexia, nausea, vomiting, restlessness, and a dry cough.
• Intestinal Upset: Both diarrhea or constipation can occur early on.
• Epistaxis: Nosebleeds are observed in about a quarter of cases.
• Lab Findings: Depression of bone marrow causes leukopenia (low WBCs), eosinopenia, and relative lymphocytosis. The classic Widal test is negative, but Blood Culture is positive.

The patient becomes severely ill and toxic as the Peyer's patches form a slough (a layer of necrotic, dead tissue).

• High Fever: Temperature plateaus, remaining constantly high, often reaching around 40°C (104°F), maintaining the relative bradycardia.
• Neurological: Delirium is common, characterized by a state of calmness, apathy, or at times, severe agitation.
• Rose Spots: Faint, pink, blanching macules (spots) appear on the lower chest and abdomen in about one-third of patients (more visible on lighter skin). They fade after 2-4 days.
• Abdominal Signs: The abdomen becomes distended and painful, especially in the right lower quadrant (over the terminal ileum).
• Pea-Soup Diarrhea: Diarrhea may occur, with stool appearing green and having a characteristic foul smell resembling pea soup. (However, severe constipation can also remain frequent).
• Hepatosplenomegaly: The spleen and liver enlarge and become tender to palpation.
• Severe Toxemia Signs: The tongue is coated with a brownish/white fur. The patient develops sordes (dark, foul crusts on the teeth and lips indicating severe dehydration and toxemia).
• Lab Findings: Widal reaction shows strong positivity. Blood cultures may still be positive, and stool cultures become positive.

This is the most dangerous phase. The slough over the Peyer's patches separates, leaving deep, raw ulcers in the intestinal wall.

• Extreme Toxicity: The patient becomes extremely ill, emaciated, and toxic. Temperature remains very high and intermittent; pulse becomes rapid and feeble.
• The "Typhoid State": The patient lapses into a profound state of apathy, muttering delirium, confusion, and fluctuating levels of consciousness (described historically as coma vigil).
• Neuromuscular Signs:
  • Carphologia: Aimless picking at the bedclothes or imaginary objects (interpreted previously as "carforragic picking").
  • Subsultus Tendinum: Involuntary twitching of the limbs and tendons (partially due to electrolyte loss, e.g., calcium in diarrheal states).
• Dehydration & CCF: Severe dehydration from profuse diarrhea leads to dry, cracked lips. Toxemia weakens the myocardium, leading to signs of Congestive Cardiac Failure (CCF).
• Gastrointestinal Emergencies:
  • Hemorrhage: Ulcers erode into blood vessels, causing sudden, massive GI bleeding (melena or hematochezia).
  • Perforation: Ulcers perforate completely through the ileum wall, spilling intestinal contents into the peritoneal cavity, leading to acute, life-threatening Peritonitis.

If the patient survives the third week, healing begins.

• The deep intestinal ulcers begin to heal slowly through granulation tissue formation.
• The fever begins to gradually decline (lysis), and other toxemia symptoms slowly reduce as the temperature normalizes.
• Recovery is protracted and extremely slow. Relapses are common (occurring in 5-10% of cases as bacteria emerge from intracellular hiding).
• If left completely untreated, typhoid fever proves fatal in up to 25% of all cases.

Accurate diagnosis relies on isolating the organism or detecting antibodies. The timing of the tests is crucial based on the disease week.

Complications generally manifest in the 3rd week of untreated illness and can affect nearly every organ system due to the systemic nature of the bacteremia and toxemia.

• Hemorrhage: Erosion of blood vessels by deep Peyer's patch ulcers causes GI bleeding (melena), leading to sudden hypovolemic shock and severe anemia.
• Intestinal Perforation: The ulcer eats completely through the ileum wall, causing intestinal contents to leak into the abdominal cavity.
• Peritonitis: Resulting from perforation; inflammation of the peritoneum causing a rigid, board-like abdomen, severe pain, rebound tenderness, and rapid progression to septic shock. Requires emergency surgery.

• Cholecystitis: The bacteria massively colonize the gallbladder, causing acute inflammation, right upper quadrant pain, fever, and tenderness. This is the primary site leading to the chronic carrier state.

• Pneumonia: Secondary bacterial pneumonia or direct typhoid pneumonia causes severe coughing, chest pain, and respiratory distress.

• Toxic Myocarditis / Heart Failure: The profound toxemia puts severe strain on the heart muscle, leading to weak pulse, arrhythmias, and congestive heart failure (fluid accumulation in the lungs and periphery).

• Typhoid Encephalopathy/Encephalitis: Severe brain inflammation leading to the "typhoid state," confusion, altered mental state, and muttering delirium.
• Meningitis: Infection spreads to the meninges (membranes covering the brain/spinal cord).
• Mental Confusion: Delirium and paranoia induced by high fever and neurotoxins.

• Osteomyelitis: Bacteria spread to the bone/bone marrow. Clinical note: Patients with Sickle Cell Disease are particularly prone to Salmonella osteomyelitis.

Management requires a multidisciplinary approach focusing on eradicating the bacteria, preventing complications, and supporting the patient's fluid and nutritional needs.

• Hospital Admission: Essential for severe cases to provide continuous monitoring for GI bleeding or perforation (checking for sudden drops in blood pressure, rising pulse, or rigid abdomen).
• Isolation / Barrier Nursing: Institute strict contact precautions. Proper disposal of all feces and urine is critical to prevent nosocomial spread.
• Hygiene & Infection Control: Meticulous handwashing by staff and patient. Limit close contact. Ensure sterile handling of food and water.
• Fluid and Electrolyte Management:
  • Monitor strict Intake and Output (I&O).
  • Administer IV fluids (Normal Saline, Dextrose 5%) for rehydration due to fever and diarrhea. Use Oral Rehydration Salts (ORS) for mild cases.
• Nutrition: Metabolism is highly elevated, but the bowel is deeply ulcerated. Provide a bland, low-fiber, soft, and easily digestible diet (high calorie, high protein) to avoid irritating the ulcers. Withhold oral feeding entirely (NPO) if perforation or severe hemorrhage is suspected.
• Symptom Control:
  • Antipyretics: Administer Paracetamol (PCM) and use tepid sponging to safely manage high fevers. Avoid NSAIDs/Aspirin as they increase the risk of GI bleeding.
  • Delirium: Keep the environment quiet and safe. Administer mild sedatives like Phenobarbital (30-60 mg) if delirium or severe agitation occurs.

Antibiotic therapy is the cornerstone of curing the infection and preventing mortality. Note: Multi-Drug Resistant (MDR) typhoid is common globally, so therapy is often guided by local sensitivity patterns.

• After clinical signs have completely passed, serial stool tests (usually 3 negative cultures taken weeks apart) must be conducted to ensure clearance.
• Patients identified as chronic carriers (bacteria residing in the gallbladder) require a prolonged 28-day course of high-dose antibiotics (often Ciprofloxacin or Amoxicillin) to eradicate the bacteria.
• In rare, refractory cases with co-existing gallstones, a cholecystectomy (surgical removal of the gallbladder) may be required to cure the carrier state.

Because Typhoid is heavily linked to poor sanitation, public health infrastructure and personal hygiene are the ultimate preventive tools.

• Safe Water Supply: Ensure drinking water is free from pathogens. Water should be boiled, chlorinated, or adequately filtered before consumption. Treat and store water properly in clean, covered containers.
• Waste Disposal: Maintain clean premises, construct proper latrines away from water sources, and ensure hygienic disposal of sewage and rubbish.
• Personal Hygiene: Wash hands thoroughly with soap and water after using the toilet, changing diapers, and before eating or handling food. Maintain short, clean fingernails.
• Food Safety ("Boil it, cook it, peel it, or forget it"):
  • Avoid high-risk, raw, or semi-cooked foods (especially raw shellfish, unpasteurized milk, and street-vendor food).
  • Food handlers must wear clean aprons and caps.
  • Scrub and rinse all raw fruits and vegetables in safe water; peeling is preferred.
  • Cook food thoroughly and serve/consume while steaming hot.
  • Refrigerate perishables and leftovers promptly; reheat thoroughly before eating.
• Carrier Exclusion: Legally exclude known infected individuals and identified asymptomatic carriers from handling public food supplies, working in restaurants, or providing direct care to children/elderly until they are medically cleared with negative stool cultures.

Vaccination is highly recommended for travelers heading to endemic areas, clinical microbiology lab workers, and close contacts of known carriers.

• Oral Live-Attenuated Vaccine (Ty21a): Given as 4 capsules taken every other day. Provides protection for about 5 years. (Requires refrigeration and cannot be given with antibiotics).
• Injectable Vi Capsular Polysaccharide Vaccine: A single IM injection given at least 2 weeks before travel. Provides protection for about 2 years.
• Typhoid Conjugate Vaccine (TCV): A newer, highly effective injectable vaccine that can be given to children as young as 6 months and provides longer-lasting immunity.