Typhoid fever

Typhoid fever is a bacterial infectious disease that is endemic in multiple countries across Asia, sub-Saharan Africa, Oceania, and Latin America.

Typhoid fever is transmitted through the ingestion of contaminated food (vegetables, dairy products, seafood) or contaminated water with Salmonella typhi bacteria. Food contamination can occur during preparation, but the bacteria can also be spread by flies that come into contact with contaminated feces or food.

Typhoid fever can be a life-threatening infection, which is why its treatment and prevention are considered top priorities in healthcare systems worldwide.

Paratyphoid fever is a bacterial infectious disease caused by Salmonella paratyphi that presents a clinical picture similar to typhoid fever. Both diseases are often grouped together due to their similarities in symptoms, diagnostic procedures, and treatment approaches.

After a period of 1-2 weeks without any symptoms, typhoid fever patients typically begin to experience a gradual onset of several symptoms.

It is usual for the fever to remain high (39-40º C) for one to two weeks and may take up to a month to resolve. Though the fever is the characteristic symptom of the disease, it is possible for a person to not experience it.

It is considered a clinical case of typhoid fever if there is a prolonged fever or at least two of the following four symptoms:

1. Headache
2. Bradycardia (slower than normal heart rate) along with fever (because the fever and rapid heart rate usually occur together)
3. Dry cough
4. Diarrhea, constipation and abdominal pain

The symptoms of paratyphoid fever are similar to those of typhoid fever, but are generally less severe in nature.

Additionally, 5 to 10% of patients may experience psychiatric symptoms, such as confusion and delusions, known as "coma vigil".

Finally, as intestinal lesions worsen, patients may experience profuse diarrhea with blood.

The convalescence period can last for months with persistent excretion of the bacteria in the stool.

Untreated typhoid fever can lead to many complications (such as cholecystitis, hepatitis, intestinal hemorrhage, intestinal perforation, or infections in other parts of the body).

In pregnant women, it may cause miscarriages or premature births.

A common complication is a relapse of symptoms two weeks after the curation, especially in those treated with antibiotics, although the reason is unknown.

In some patients, the bacterium can remain in the body (gallbladder) for a long time without causing disease but with the possibility of infecting others (carrier state).

Approximately 2-5% of individuals can become asymptomatic carriers of Salmonella, potentially remaining infectious and capable of spreading the disease to others.

The diagnosis of typhoid fever (and paratyphoid fever) requires the fulfillment of three types of criteria:

• Clinical criteria: The symptoms already mentioned must be present to establish a clinical case.
• Laboratory criteria: Isolation of Salmonella bacteria in a sample for culture that can be from stool, blood, or bone marrow.
• Epidemiological criteria: At least one of the following three situations must be present:
  1. Exposure to the same source that caused another case of typhoid fever.
  2. Contact with a patient with typhoid fever.
  3. Exposure to food, water, or animals with Salmonella.

An outbreak of typhoid fever is diagnosed with two or more cases in contact with the same source of contamination.

Additional laboratory tests or rapid diagnostic tests are not recommended as they are not useful.

Treatments are based on:

• Antibiotics: Ideally, they should be administered after an antibiotic sensitivity test because in many parts of the world, antibiotic resistant bacteria are emerging. The most commonly used are fluoroquinolones, especially ciprofloxacin. Others include chloramphenicol and third-generation cephalosporins.
• Supportive measures: Hydration, frequent meals, rest, and avoidance of laxatives and enemas. Intravenous fluids when necessary.
• Treatment of relapses: Same as initial disease, but for only 5 days.
• Treatment of carrier state: Antibiotics (trimethoprim-sulfamethoxazole, amoxicillin, or fluoroquinolones) are used for four weeks, and when necessary, the gallbladder is removed.

The prevention measures for typhoid fever include:

• Primary preventive measures: consumption of uncontaminated water, effective sewage systems, pasteurization of milk, and control of food handlers.
• Adequate facilities and education to promote handwashing, especially for food handlers and caregivers of children and the elderly.
• Control of fly populations.
• Avoiding consumption of raw fish and seafood.
• Maximizing the avoidance of contagion by proper disposal of excretions and continuous handwashing with soap and water in the household of confirmed cases.
• Obtaining three consecutive negative stool cultures with one-week intervals during convalescence to rule out carrier status.
• Treating all carriers.
• Epidemic control measures: reporting of cases and vaccination. Currently, vaccination is recommended for international travelers, people who handle the bacteria in laboratories, and individuals in close contact with people with the disease.
• Travelers to endemic areas should be cautious with food and drinks, opting for a diet of packaged and well-cooked foods, and boiling or chlorinated water.