Discussion
The case illustrates the acute multi-bacterial infection ofSalmonella typhi and Orientia tsutsugamushi in patient
with Dengue fever. All the diagnosis was made on the basis of rapid
serology test kit. Rapid serology kits can be questioned for their
accuracy, but due to lack of resources in the settings and deteriorating
condition of patient, the need for quick diagnostic approach was needed.
Clinical laboratory parameters also played a vital role for taking the
medical decision in addition to rapid serological tests. Other tests
such as ELISA and/or polymerase chain reaction would lead to more
confirmatory identification but were not accessible.
Dengue infection was diagnosed based on IgM positivity. Manufacturer (SD
Bioline™ Dengue Duo, Abbott, Santa Clara, USA) reported sensitivity of
94.2% and specificity of 96.4% for diagnosis of acute IgM dengue
infection. Salmonella typhi IgG/IgM (Bioline Diagnostics LLP,
Delhi, India) was also identified based on IgM positivity with
sensitivity and specificity of 91% and 99.3% respectively. Suspecting
the possible cross-reactivity of Rapid Salmonella typhi IgM in
dengue fever, which is also concluded with the study performed by Bhatti
et al, follow-up test was
requested5. Three to
four days following the initial test, a follow-up test showed that both
the IgG/IgM tests for S. typhi and dengue were IgG positive. The
study performed by Bhatti et al concluded cross-reactivity based on
positive S. typhi IgM but negative IgG on dengue patients using
rapid kits but our test showed positive IgM-Ab on initial test and
subsequent IgG positivity on
follow-up5. ImmuneMed
Scrub Typhus Rapid test kit was used for qualitative detection of
IgM/IgG Ab specific to Orientia tsutsugamushi. The sensitivity
and specificity was 97.3% and 99.7% respectively.
Our patient works primarily in agricultural fields in Dang district of
Nepal. Her work may have had her be exposed to ticks and mites.
Furthermore, climatic condition as well as seasonal factors also played
a role in co-infection4. Various studies and
case reports have been documented regarding co-infection of Dengue virus
and scrub typhus 6,
scrub typhus and enteric fever7 as well as dengue and
enteric fever 8 in
Nepal. Few cases of all three i.e. dengue, scrub typhus and S.
typhi co-infection was reported in
India9. A study
conducted by Murdoch DR et aldid not observe any eschar in patient with
scrub typhus-typhoid co-infection which is also consistent with our
non-finding of eschar7.
Thrombocytopenia, transaminitis, hyperbilirubinemia along with
subsequent hypoalbuminemia was seen in our patient which is also
consistent with dengue-scrub infection as conducted by Basheer A et al10. Another study in
scrub- typhoid and dengue- typhoid co-infection revealed low hemoglobin
level, thrombocytopenia, and increase in transaminases level11,12.