Recent advances in enteric fever by Dr. Diwan (D1) Shrestha

1. Recent advances in
ENTERIC FEVER
By DIWAN SHRESTHA
INTERN
Department of Paediatrics, NMCTH

2. Newer Diagnostic
Methods
1. Recent advances include the IDL Tubex® test
by a Swedish company, which reportedly can
detect IgM O9 antibodies.
 The O9 antigen used in the test is extremely
specific because its immunodominant epitope is
a rare dideoxyhexose sugar in nature.
 This antigen has been found in serogroup D
salmonellae but not in other microorganisms.
 A positive result given by Tubex® invariably
suggests a Salmonella infection.

3. Newer Diagnostic
Methods Cntd
 Tubex® detects IgM antibodies but not IgG. This
makes it invaluable as an aid in the diagnosis of
current infections.
2. Another rapid serological test, Typhidot®, makes
use of the 50 kD antigen to detect specific IgM
and IgG antibodies to S. Typhi and takes three
hours to perform.

4. Newer Diagnostic
Methods Cntd
 This dot enzyme immuno assay (EIA) test offers
simplicity, speed, specificity (75%), economy,
early diagnosis, sensitivity (95%) and high
negative and positive predictive values.
 The detection of IgM reveals acute typhoid in
the early phase of infection
 The detection of both IgG and IgM suggests
acute typhoid in the middle phase of infection

5. Newer Diagnostic
Methods Cntd
3. A newer version of the test, Typhidot-M®, was
recently developed.
 It detects specific IgM antibodies only.
 This test can replace the Widal test, when used
in conjunction with the culture method, for the
rapid and accurate diagnosis of typhoid fever.

6. Newer Diagnostic
Methods Cntd
4. The typhoid IgM dipstick assay is also being
designed for the serodiagnosis of typhoid fever ,
through the detection of S.Typhi specific IgM
antibodies in serum or whole samples.
5. Salivary IgM test has also been used, though
not yet available.

7. Newer Diagnostic
Methods Cntd
6. There has been study on validation of a
PCR for diagnosis of typhoid fever and
salmonellosis by amplification of the hilA
gene in clinical samples from Colombian
patients.
But, it may not be cost-effective.

8. Newer Treatment
methods
Resistance to third and fourth generation
cephalosporins is emerging and will gain
significance in the coming decade.
Azithromycin has shown promise in a
limited number of trials.
The main advantage of aztreonam and
azithromycin is that they can be used in
children and in pregnant or nursing
females.

9. Newer Treatment
methods
 Quinolones and zidovudine have a synergistic
antibacterial effect against Salmonella
administration of both drugs may dramatically
decrease the risk of recurrent infection.
 The use of glucocorticoid has been advocated
for the treatment of severe typhoid fever based
on a randomized, double blind, placebo
controlled trial carried out in Indonesia
 This study showed a significant reduction in
mortality in patients with severe typhoid fever

10. Vaccines against
Typhoid Fever
Two vaccines against typhoid fever
(Parenteral Vi polysaccharide and oral
Ty21a) have been licensed in many
countries
 A new typhoid vaccine composed of the Vi
capsular polysaccharide has been
reported
• The Vi polysaccharide vaccine has been
put to trial and provided more than 65%
protection

11. Vaccines against
Typhoid Fever
 Attenuated Salmonella type vaccine Strain CVD
908, which harbors deletion mutation, in aro-C
and aro-D has been shown to be well tolerated
and highly immunogenic
 A further derivative prepared by introducing a
deletion in htr-A resulted in CVD 908-htr A
 Both CVD 908 and CVD 908-htrA are useful as
live vector vaccines to deliver foreign antigens to
the immune system