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Typhoid/Enteric fever

Enteric fever is a systemic syndrome

produced by a group of certain Salmonella

organisms

Typhoid feverS.Typhi

paratyphoid feverS.paratyphi- A,B or C

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Background: Typhoid fever, also known asenteric fever, is a systemic infection/syndromeby Salmonella typhiorSalmonella paratyphi

A,B,C(less virulent).

Since ancient times, these bacteria have thrivedduring wartime and during the breakdown ofbasic sanitation.

S typhi:developing nations where sanitation is

generally poor. Sporadic outbreaks occur in developed nations,

H/O travel to endemic areas

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Epidemiology

Of all Salmonella serotypes, only S typhi

and S paratyphiare pathogenic

exclusively in humans.

Typhoid fever is potentially fatal if

untreated

Humans are the only natural reservoir , so

direct or indirect contact with an infected

person (sick/carrier) is necessary for inf

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Mode of transmission

1)Ingestion of food or water contaminated with

human excreta/sewage-most common

2)Water borne outbreaks - poor sanitation

3) direct fecal-oral spread - poor personal hygiene

4)Oysters and shellfish cultivated in water (1)

5) International travellers to Asia, Latin America

6)Cong transmission-transplacental or intrapartum

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Pathogenesis

After ingestion the bacilli reach the intestine,passing the gastric barrier.

Attach to the microvilli of the ileal brush border &

invade the intestinal epth thru the peyerspatches

Reach the int lymph nodes,multiply within themononuclear cells

Monocytes unable to destroy the org.in earlystages of the dis.carry them to the mesentericlymph nodes and

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Thru the thoracic duct reach the blood

stream transient bacteremia

Reach the RES and other organs&

proliferate bacteremia recurs

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Pathogenesis

Hyperplasia of the peyers patches with

necrosis &sloughing of the epithelium,

produce ulcers(longitudinal) that may

bleed, but heal without scarring.

The inflammatory lesion may penetrate the

muscularis and the serosa of the intestines

perforation

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Mesenteric lymph nodes, liver, gall bladder(GB)

and spleen are inflammed with focal necrosis.

Local multiplication of the organism in the walls

of GBlarge no. of salmonellaintestines Hyperplasia of the reticuloendothelial tissues

with proliferation of mononuclear cells is the

predominant finding, areas of focal necrosis

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After a period of transient bactremia, the bacilli rseeded in various organs, liver, spleen,gallbladder, & bonemarrow, further multiply

This phase heralds the onset of clinical illness.

Bile serves a good culture media for the org tocontinue multiplying and the gall bladderdischarges large no. of org. into the intestines

Peyers patches and other lymphoid follicles get

inflammed and slough off to form typhoid ulcersand lead to the 2 most dreaded complications ,hemorrhage and perforation

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Salmonellae are grouped based on the somaticO antigen and further divided into serotypesbased on flagellar H and surface virulence (Vi)antigens.

S typhi, the cause of typhoid fever, has O and Hantigens, an envelope (K) antigen, and alipopolysaccharide macromolecular complexcalled endotoxin that forms the outer portion ofthe cell wall.

S typhi, S paratyphi C, and Salmonella Dublinare the only Salmonella serotypes that carry Viantigen

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It is an imp public health problem

Recently it has developed increasing bact

resistance to various antibiotics

Gram negative bacilli,motile and have

flagella.

They possess flagellar antigen H andsomatic antigen O

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Epidemiology: S.typhioccurs only in

humans

Transmission: feco oral route ,thru

contaminatedwater or food

Acutely infected patients excrete bacilli in

their stool or urine for a variable period

5% of the adults become chronic carriers

(resevoir)

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Food handlers and cooks are potent

source of infection

Most of the infected children stop

excreting the bacilli within 2 -3 mths and

rarely become carriers

Epidemics occur : contaminated drinking

water, poor sanitation and personal

hygiene, overcrowding & poverty

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Older children & young adults most

infected ,10% occur in under 5s and 1-2%

below 2yrs of age

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Clinical picture

Incubation period: 7- 14 days, (3-30days)

Clinical manifestations depend on age:

school-age &adolescents:

First week:

Onset is insidious, fever, malaise, anorexia,

myalgia, headache &abd pain over a period of 2

3 days,(more severe in the 2

nd

week)Diarrhea-pea soup consistency initially, later

constipation is prominent

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Temp rises in a step ladder pattern,

becomes unremitting ,high within a week

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Rose spots in 50% cases ,macular or

maculopapular,discreet,erythematous,1-5

mm, blanch on pressure

Appear in crops ,10-15 on the lower chest

and abdomen, last for 2 -3 days,culture of

the lesion positive forS.Typhi

Rhonchi and rales on auscultation

If no complications ,resolve in 2- 4 weeks

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Malaise and lethargy may persist for 1-2

mths

Patient may be emaciated by the end of

the illness

enteric fever by non typhoidal salmonella

is milder

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Infants and young children: RARE, milder,

present as acute gastroenteritis, LRTI, or

VF

Neonates: transmission is vertical. Begins

within 3 days of delivery.vomiting,

diarrhea, and abd distension are

common. temp variable 40.5 C seizures,hepatomegaly, jaundice, wt. loss

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Diagnosis: Culture of the organism is the

basis

1st week: Blood culture

2nd week: Agglutination test

3rd week: Stool culture

4th

week: Urine culture BASU

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LAB FINDINGS:anemia, normochromic,

normocytic blood loss/bonemarrow depression

Leucopenia , never below 2,500

leucocytosis,20,000-25,000(abscess)

Thrombocytopenia

LFT deranged

ProteinuriaPUS &RBCs in stool

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D/D: GE

VF

BRONCHITIS /BP LATER ; SEPTICEMIAS

ANICTERIC HEPATITIS

LEUKEMIAS /LYMPHOMAS

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Treatment

Antibiotic is essential for treating entericfever.

The fluoroquinolones and third generation

cephalosporins are the current mainstay oftherapy.

Ceftriaxone recommended for ped age grp

80mg/kg/day in a single dose

Relapse rate is low and prevents carrierstate

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Quinolones have the adv of dose and costeffective

Probable toxic effect on growing cartilage,

not recommended A short course of steroids improves the

survival rate of patients with shock,

obtundation, stupor/coma. initial dose of dexamethasone 3mg/kg

followed by 1mg/kg 6 hrly for 48 hrs

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Supportive treatment & maintenace of fluid

and electrolytes ,

Surgical intervention

Blood transfusion

Diet

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Complications

Intestinal hemorrhage & perforation after

the first week

Hemorrhage : drop in temp &blood

pressure increase in pulse rate

Perforation : marked increase in abd pain,

tenderness, vomiting& signs of peritonitis.

Pneumonias : superinf

Toxic myocarditis, myogenic shock

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Neurological :increased intracranial

tension, thrombosis, ataxia, chorea,

aphasia, deafness, psychosis& transverse

myelitis. Permanent sequlae are rare.

Osteomyelitis and septic arthritis are more

common in kids with hemoglobinopathies

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Prognosis

Depends on prompt therapy, age, previous

state of health, Salmonella serotype and

the appearance of complications

In developing coutries , mortality rate is

higher 10%.

Relapse known to occur in untreated

cases, (numerous), milder, shorter

duration

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Carriers :

Risk is low in kids and increases with age

Patients who excrete S.typhi@ 3mths orlonger,are excretors @ one yr &defined as

chronic carriers.

Incidence of biliary tract dis is higher.

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Prevention

Improved sanitation & clean water,

essential

Personal hygiene measures,

handwashing,

Attention to food prep practice

Course of 4-6 wks of high dose ampicillin(amoxycillin) plus probenecid or TMX-SMX

Ciproflox in adults, cholecystectomy

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Vaccines:3 types available

Parenteral , inactivated vaccine confers

limited protection(50-75%) ass with side

effects.

Approved for children 6 mths and above

2 doses (0.25ml -6mths-10yrs) &( 0.5ml-

above 10yrs),S/C, 4 weeks apart.

Boosters every 3 yrs necessary

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Oral live vaccine Ty21a strain (80%)

Three capsules given on alternate days,

repeated every 3yrs

Not recommended

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Vi polysacch typhoid vaccine : Vi antigen

is a capsular antigen

Effective after the age of 2 yrs

0.5 ml I/M deltoid area ,booster 2-3 yrs

yrs

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