Fever Mysteries: Typhoid & Paratyphoid

Typhoid is an acute systemic illness caused by infection due to salmonella typhi. A fever similar to typhoid is caused by salmonella paratyphi, which is called paratyphoid fever. 

Typhoid is characterised by fever, malaise, pain abdomen, rash and lecupenia. The untreated patients may develop complications during 2nd and 3rd week due to toxaemia ( blood poisoning by toxins from a local bacterial infection ) and septicaemia ( Condition in which bacteria enter the bloodstream and cause blood poisoning )

Unraveling The Culprits 

The sequence of events that occur during the course of typhoid fever and development of pathological lesions is as follows 

• First of all, Salmonella typhi infects peyer’s patches of small intestine and multiples there without causing damage to the intestine. Then it enters the bloodstream producing a short period of asymptomatic bactereraemia.
• Now the viable bacteria re-enter the intestine and localise in the lymphoid tissue of the small intestine multiply and produce continuous bacteraemia for days and weeks.
• During the phase of persistent bacteraemia, lymphoid follicles lead to ulceration and bleed. During this period, salmonella typhi enters other organs and produces bacteraemia. 
• All late clinical manifestations and complications are due to endotoxemia of typhoid fever. 

Symptoms And Signs OF Typhoid And Paratyphoid Fever

•  First 5 – 7 days ( Before 1st week ) 
  •  Remittent fever
  •  Aches
  •  Malaise
  •  Headache
  • Constipation
  • Leucopenia
  •  Relative bradycardia

• Between 1st and 2nd week 
• •  Rose spots
  •  Bronchitis
  • Abdominal pain
  •  Abdominal distention
  • Diarrhoea

• Beyond 2nd week 
• •  Confusion
  • Delirium
  •  Complications
  •  Coma
  •  If untreated death may occur. 

Laboratory diagnosis 

Suspected fever may be based on symptoms, medical and travel history. The diagnosis of typhoid fever is confirmed when there is a presence of Salmonella typhi a sample of blood. Laboratory diagnosis can be based on the triggering range of the symptoms. 

First week 

• There may be normocytic normochromic anaemia, leucopenia, and albuminuria. 
• Blood culture may be positive in 70 to 90 % cases. 

Second week   

• Anaemia, leucopenia may persist.
• Widal tests become positive, and may show a four-fold rise in agglutinins against somatic ‘O’ antigen.
•  Blood culture may be positive. 
• In case of negative blood culture, bone marrow culture is indicated. 
• In Case of paratyphoid, several reports have shown that culture from bone marrow specimens is more sensitive when isolating S. paratyphi.
• In 80% to 95% of cases, the culture of bone marrow showed positive results

Third week 

• Anaemia and leucopenia persist. 
• Blood culture is positive in only 30 to 40 % cases. 
• Positive Widal test with rising titres.
• Positive urine culture for S.typhi. 

Treatment Tactics

Several antibiotics are effective against salmonella typhi. Antimicrobial resistance is common with likelihood of more complicated and expensive treatment options required in the most affected regions. The change of antibiotics may be needed in multi-drug resistant typhoid, where choice of antibiotics will be according to culture and sensitivity. Following instructions should be followed when being treated for typhoid fever : 

•  Take prescribed antibiotics according to doctors instructions.
•  Avoid serving food for other people.
•  Wash hands with the soap properly after using the washroom.
•  Have proper laboratory tests to ensure the presence of salmonella typhi bacteria remains in the body.  

Prevention : shielding against bacteria 

Immunisations may be used for household contacts for travellers to endemic areas and during endemics. Vaccination plays an important role in preventing typhoid fever. Typhoid conjugate vaccine, consisting of the purified Vi antigen linked to a carrier protein, is given as a single injectable dose in children from 6 months of age and in adults up to 45 years or 65 years. Typhoid vaccination should be compulsory to travellers, to destinations will help ensure safety measures, which are as follows : 

• Avoid raw milk and products made from raw milk.
• Ensure food is properly cooked, when eaten. 
• After coming in contact with pets or animals, wash hands properly with soap. 
• Wash fruits and vegetables properly. If possible, vegetables and fruits should be peeled.
• Drink boiled water. 
• Avoid ice unless it is made from safe water.

Complications 

A typhoid fever now-a-day does not remain enteric fever but is a systemic disorder. A Large number of complications may occur during the second week or onwards which are divided into two groups which are intestinal and extra-intestinal. Intestinal includes haemorrhage ( bleeding from the intestine ),  paralytic ileus ( condition where the motor activity of the bowel is impaired ), peritonitis ( redness and swelling in the abdomen ), and perforation ( a hole that develops through the wall of a body organ ). Extra-intestinal includes pneumonia, nephritis, bone and joint infection, meningitis etc.