Typhoid fever
Introduction
Typhoid fever, also known as enteric fever, is a potentially severe and life-threatening infection caused by the bacterium Salmonella enterica serotype Typhi. It is a systemic disease characterized by fever and abdominal pain, and it is spread through contaminated food, water, or close contact with an infected person.
Etiology
Typhoid fever is caused by the bacterium Salmonella enterica serotype Typhi, a Gram-negative bacterium. Unlike other Salmonella species, S. Typhi is adapted to humans and does not occur in animals. Another serotype, Salmonella enterica serotype Paratyphi, can cause a similar but usually less severe illness known as paratyphoid fever.
Transmission
Typhoid fever is transmitted through the fecal-oral route. The bacteria are ingested by consuming contaminated food or water. The bacteria can survive in water and on surfaces for several weeks. People who recover from typhoid fever can continue to carry the bacteria, becoming long-term carriers and can spread the disease.
Pathogenesis
Once ingested, the bacteria pass through the stomach and multiply in the intestinal tract. They then penetrate the intestinal wall and enter the bloodstream. From there, they spread to various tissues and organs, such as the liver, spleen, and bone marrow.
Clinical Manifestations
The incubation period of typhoid fever is usually 1-2 weeks, and the duration of the illness is about 3-4 weeks. Symptoms include high fever, malaise, headache, constipation or diarrhea, rose-colored spots on the chest, and enlarged spleen and liver. If not treated, the illness can lead to serious complications, such as intestinal bleeding or perforation.
Diagnosis
Diagnosis of typhoid fever is made by detecting the bacteria in blood, bone marrow, or stool samples. The Widal test, although commonly used in developing countries, has low sensitivity and specificity. More accurate tests, such as blood cultures, are preferred but are not always available in resource-limited settings.
Treatment
Typhoid fever is treated with antibiotics. The choice of antibiotic is guided by the susceptibility pattern of the S. Typhi strain, which varies by geographic region. In recent years, multi-drug resistant strains have emerged, complicating treatment.
Prevention
Prevention of typhoid fever involves improving sanitation and vaccination. Two vaccines are available: an oral live attenuated vaccine and a parenteral inactivated vaccine. Both vaccines are about 50-80% effective.
Epidemiology
Typhoid fever is a global health problem, especially in developing countries with poor sanitation. It is estimated that about 21 million cases and 200,000 deaths occur each year worldwide.
History
Typhoid fever has been recognized since ancient times, but the bacterium was first isolated by Karl Joseph Eberth in 1880. The disease was a major cause of illness and death in the crowded, unsanitary conditions of military camps and urban areas until the early 20th century.