Typhoid Fever

TYPHOID AND PARATYPHOID

(ENTERIC) FEVERS

OBJECTIVES

At the end of this lecture the student is supposed to:
Mention the etiology of typhoid fever
Write brief notes on epidemiology of typhoid fever.
Discuss the pathology of enteric fever
Talk about the clinical features of typhoid fever
Define paratyphoid fever.
Mention the prognosis of typhoid fever
Enumerate the complications of typhoid fever
Recall the investigations that are done to diagnose typhoid fever.
Discuss the management of typhoid fever.
Mention the prognosis of typhoid fever.

TYPHOID AND PARATYPHOID

(ENTERIC) FEVERS


Aetiology
Typhoid fever is caused by Salmonella typhi
Paratyphoid fever is caused by S. paratyphi A and B
They are Gram-negative enteric bacilli, belonging to the family Enterobacteriaceae
It is isolated in 1880 by Karl J. Erberth,

Epidemiology

Typhoid is a worldwide disease
It affects roughly 17 million people annually.
Causing nearly 600,000 deaths.
Humans are the only known natural reservoir.
Transmitted the fecal-oral route
The earliest recorded epidemic occurred in Jamestown.
6,000 people died of typhoid fever in the early 17th Century.
It is important cause of fever in developing countries as India, sub-Saharan Africa and Latin America.
Elsewhere they are relatively rare

Pathology

The bacteria are ingested in drinking water, milk, or solid food contaminated by urine and feces of infected individuals.
The inoculum size necessary for infection is 100,000 bacteria.
The bacteria reach via the lymphatics to the submucosal lymph nodes of the terminal ileum. There they multiply in the small intestine over a period of 1-3 weeks.
From the intestinal submucosal lymph nodes it dissimnate to the blood producing bacteremia (for few days).
Thereafter it is dissiminated all over the body but mainly localize in the lymphoid tissue of the small intestineforming what is called Peyer's patches and follicles → swell → ulcerate→ heal. These patches may perforate or bleed.


Clinical features
Incubation period of typhoid fever is about 10-14 days, but of paratyphoid is shorter.
Onset -may be insidious
Features in the first week (week of bacteremia)
Fever is an important symptom. The temperature rises in a stepladder fashion for 4 or 5 days.
The pulse shows a relative bradycardia and diacritic character.
Malaise, headache ,and drowsiness
Epistaxis –may develop
Myalgia and aching in the limbs.
Constipation may be present, succeeded by diarrhea and abdominal distension with tenderness.
In children diarrhea and vomiting may be prominent early in the illness.
At the end of first week Rose Spots may appear on the upper abdomen and on the back. They are sparse, slightly raised, 1-2 mm, rose-red spots, that fade on pressure, and usually visible only on white skin.
Features in the second week
Splenomegaly appears in the 7th-10th day. It is soft.
Bronchitis- may develop with cough, and diffuse rhonchi
Abdominal distension
Diarrhoea
At the end of second week the patient may be profoundly ill unless the disease is modified by antibiotic treatment.
At the end of the second week the patient shows;
Toxic facies
Coated tongue
Musty odor
Mental confusion
Delirium
Complications may occur
The third week
Toxaemia increases
Complications are frequent.
The patient may pass into coma and die if untreated (rare in countries with developed health services).
Following recovery (spontaneous or after therapy
Up to 5% of patients become chronic carriers of S. typhi. Classically such patients have gallbladder disease.
The bacilli may live in the gall bladder of carriers for months-years after clinical recovery
The bacilli pass intermittently in the stool and less commonly in the urine.


Paratyphoid fever
The course tends to be shorter and milder than that of typhoid fever
The onset is often more abrupt with acute enteritis.
The rash may be more abundant
The intestinal complications less frequent.

Prognosis

Most of cases recover spontaneously
20% of untreated cases develop complications and may be death.

Complications

Complications due to septicaemia during the first week:
Cholecystitis
Pneumonia
Arthritis
Osteomyelitis
Meningitis
Bone and joint infection (especially in children with sickle-cell disease).
Myocarditis
Nephritis
Complications due to perforation of ulcerated Peyer's patches:
Haemorrhage
It may occur at the end of the 2nd week or during the 3rd week of the illness.


Investigations
In the first week (the week of bacteremia)
Clinical diagnosis may be difficult as the symptoms are those of a generalised infection (bacteremia) without localising features.
A white blood count - typically a leucopenia.
Blood culture is the most important diagnostic method in a suspected case during this period.
Proteinuria (often present)

In the second and third weeks

The faeces and urine culture will contain the organism more frequently
The Widal reaction detects antibodies to the causative organisms.
It is not a reliable diagnostic test
It should be interpreted with caution

Management

Chloramphenicol (500 mg 6-hourly)
Ampicillin (750 mg 6-hourly)
Co-trimoxazole (2 tablets or i.v. equivalent 12-hourly)
All these drugs are important therapies but are losing their effect due to resistance in many areas especially India and South-east Asia.
Fluoroquinolones are the drugs of choice (e.g. ciprofloxacin 500 mg 12-hourly).
Ceftriaxone and cefotaxime are useful alternatives but have a slightly increased treatment failure rate.
Azithromycin (500 mg once daily) is an alternative where fluoroquinoline resistance is present. It has not been validated in severe disease.
Treatment should be continued for 14 days.
Pyrexia may persist for up to 5 days after the start of specific therapy.
Even with effective chemotherapy there is still a danger of:
Complications
Recrudescence
Development of a carrier state.
The chronic carrier should be treated for 4 weeks with ciprofloxacin
cholecystectomy may be necessary in some case


Prevention
Improved sanitation and living conditions reduce the incidence of typhoid.
Travellers to countries where enteric infections are endemic should be inoculated with one of typhoid vaccines:
Inactivated vaccine- injectable
Attenuated live- oral.