Typhoid fever – An overview
Cause of Typhoid fever
Typhoid fever or Enteric fever is a potentially fatal bacterial infection caused by the bacteria, Salmonella typhi. It’s common in developing countries and accounts for approximately 200 000 deaths every year.
How does it infect? /Pathophysiology
Salmonella typhi primarily infects a part of the immune system known as the reticuloendothelial system. It enters the body through the gastrointestinal system where it penetrates the wall of the intestine to get caught up by the immune cells. The immune cells present the pathogen to the lymphoid tissues within the intestinal wall (Peyer patches). Through it, the bacteria enter the circulation and seed into the gallbladder directly or via the liver. It hides and proliferates inside the gallbladder. As the number increases, bacteria re-enter the intestine along with the bile secreted by the gallbladder. Most of the them, re-infect the Peyer patches. This cycle repeats again and again. Ultimately it causes severe inflammation and destruction of the payer patches. The bacteria that failed to re-infect the Peyer patches pass through the stools. Therefore, contaminated food and water are the main modes of transmission.
Clinical course and the symptoms of typhoid fever
Since multiple cycles of bacterial invasion are needed for the disease manifestation, symptoms have a gradual onset and progression. Furthermore, the symptoms have a characteristic pattern, disseminated in time.
During the 1st week of infection gastrointestinal symptoms predominate. It includes:
- Abdominal pain and tenderness
- Abdominal bloating (distension)
- Dry cough
- Frontal headache
- Whitish coated tongue
- Fever that shows a stepwise rising pattern; Each day the fever is higher than the previous day
During the 2nd week following symptoms and signs start to appear
- Rose spots – Pinkish spots of the body
- Relative bradycardia; heart rate is low relative to the body temperature
- Enlarged liver and spleen
- Previous abdominal symptoms worsen
As the patient enters the 3rd week, the condition becomes severe. The following changes are characteristics of the 3rd week.
- Severe abdominal distension
- Diarrhea similar to a pea soup
- Mental disorientation
- Neurological defects
- Sepsis and shock
Untreated patients who have proceeded to the 4th week, usually are in an unconscious or comatose state. However, if the patient survives the 4th week, he will gradually recover. Having said that, some neurological defects may remain even after a complete recovery.
Complications of typhoid fever
- Intestinal perforations and intestinal bleeding are extremely common in untreated patients.
- Pneumonia is common during the 3rd week.
- Myocarditis (heart muscle damage)
- Neurological damage
- Septic shock and multi-organ failure
Rarely, about 1-2% of the infected people (particularly females) become carriers, a state where the person harbors the bacteria in the gallbladder without having any symptoms or complications. Yet they are capable of spreading the infection. Typhoid Mary (a cook) was such a woman who lived in 19th century and she was responsible for 51 typhoid infections and 3 typhoid deaths.
Diagnostic tests for typhoid fever
The gold standard method of diagnosis is the isolation of Salmonella typhi by bacterial culture. This is done using blood and stool samples of the patient. Along with it, an antibiotic susceptibility test (ABST) is also done.
Serological tests to find antibodies against the bacteria is a widely available diagnostic method.
Polymerase chain reaction (PCR) for bacterial antigens is a rapid diagnostic test with high accuracy.
Treatment of typhoid fever
Since diagnostic tests take time, treatments are initiated on clinical suspicion without any laboratory confirmation. Later it’s adjusted or changed according to the findings.
Typhoid fever is primarily treated with antibiotics. At 1st, broad-spectrum antibiotics are given until the results of the bacterial culture and ABST arrives. Once the necessary information is available, treatment is narrowed down. Along with the antibiotics, supportive medical therapies are given depending on the patient’s status. If the patient has developed complications like intestinal perforations, surgical treatment is needed.
Diet in Typhoid fever
Only the soft, digestible foods are preferred to be given orally. If the patient has intestinal perforations, intravenous/ parenteral nutrition is needed. In general, the following advices are given to a Typhoid patient with regards to the diet.
Eat small, easily digestible meals frequently. Don’t eat high fiber food.
Eat soft cooked vegetables like mashed potatoes and fruits like banana or apples.
Avoid heavy foods, deep-fried foods, fatty (butter) or spicy foods.
If diarrhea is present increase the fluid intake. Always drink clear fluids.