Page 140 - JSOM Summer 2018

TABLE 2 Laboratory Testing Results of Seroprevalence Study in strains of Salmonella are present in Georgia and that these
Military Personnel, October 2014–February 2016 are responsible for the high degree of prevalence noted in this
Seropositive study and many of the reported cases of gastrointestinal ill-
Assay patients, No. (%) ness. This is an especially attractive hypothesis given that Sal-
Brucella spp IgG ELISA 51 (5) monella exposure was detected in sera of patients from every
Leptospira spp IgG ELISA 28 (2.8) region of the country and given that most patients originated
Coxiella burnetii, IgG ELISA 6 (0.6) from the capital of Tbilisi (where most travelers tend to stay
Salmonella enterica serovar Typhi IgG ELISA 233 (23) during their visit). Furthermore, it can be hypothesized that
CCHFV IgG ELISA 10 (1) native Georgians have developed an immunity to many of the
Hantavirus IgM ELISA 59 (5.9) endemic Salmonella strains via repeated exposure, whereas vis-
itors, lacking a history of repeated exposure, are susceptible to
WNV IgG ELISA 8 (0.8) illness. If true, this hypothesis would resolve the discrepancy
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Francisella tularensis IgG ELISA 61 (6.1) between the high level of seroprevalence among Georgian mil-
Bacillus anthracis IgG ELISA 32 (3.2) itary recruits and the general absence of reported symptoms.
Rickettsia Typhus group IgG ELISA 19 (1.9)
Rickettsia Spotted Fever group IgG ELISA 22 (2.2) Interestingly, similar seroprevalence was detected between
Borrelia burgdorferi IgG ELISA 13 (1.3) common and uncommon pathogens. For example, the se-
Bartonella henslae/B quintana IgG 57 (5.7) roprevalence for Brucella spp, hantavirus, F tularensis, and
CCHFV, Crimean-Congo hemorrhagic fever; ELISA, enzyme-linked Bartonella spp were 5%, 5.9%, 6%, and 5.7%, respectively.
immunosorbent assay; IgG, immunoglobulin G; IgM, immunoglobu- Among these pathogens, Brucella spp are endemic to Georgia
lin M; WNV, West Nile virus. and are a common cause of human disease (100–150 cases per
year), F tularensis is endemic to Georgia but disease cases are
especially dangerous pathogens, 3.2%were seropositive for rare (1–2/year), hantavirus infection is rarely described, and
Bacillus anthracis, 5% were positive for Brucella spp, and Bartonella is an uncommon but emerging pathogen. 15–17
about 6% were positive for either F tularensis or hantavirus.
The seroprevalence of F tularensis was low compared with
The largest number of total seropositive patients came from the that of neighboring countries. For example, the seropreva-
Shida-Kartli region in east-central Georgia and the lowest num- lence of F tularensis in Azerbaijan was greater than 15%.
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ber of total seropositive patients came from the Racha-Lech- However, this may be due to sampling error, and although it is
khumi and Kvemo Svanteti region in northern Georgia (Figure reflective of the military-age population in Georgia, it may not
1; Table 3). Significantly, S Typhi and Brucella spp. were the reflect the population as a whole.
only two bacterial agents and hantavirus was the only viral
agent that gave positive serologic results in sera collected from Oral communication with clinicians has revealed that Lyme
patients originating from every region of Georgia, which poten- disease is often encountered in routine clinical practice in
tially indicates widespread distribution. It was noted that rural Georgia. However, presently, there is very little published in-
residence alone was not related to the rate of seropositivity (in formation about prevalence or geographic distribution of this
this study, sera positive for all of the agents under study were disease in the region. Recent reports have listed Lyme borreli-
only derived from patients originating from Tbilisi, the capital osis among the endemic diseases in Abkhazia, a breakaway
city of Georgia). Logistic regression analysis of risk factors did region of Georgia, and it is well known that Lyme disease is
not reveal statistically significant differences in seropositivity common in several neighboring countries, including Turkey
for exposure to any agent under study between groups with and Russia. In addition, the vector of Lyme disease, Ixodes
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or without known risk factors. Furthermore, none of the par- ricinus, has been detected at 67 locations throughout Geor-
ticipants had a medical history that was significant for signs gia. As a whole, these factors indicate that Lyme borrelio-
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or symptoms associated with any of the pathogens evaluated. sis is a potentially important and underdiagnosed disease in
this country. However, only 1% of the patients in this study
Discussion were seropositive for Borrelia spp, and this factor was not pos-
itively associated with regions bordering endemic countries.
Interestingly, the highest seroprevalence was detected for S Ty- Additional research will be required to fully characterize the
phi. Although this result may indicate a high degree of prev- geographic spread of this disease and to identify regional res-
alence of this organism in Georgia, it is also possible that it ervoirs and hot spots.
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stems from antibody cross-reactivity. Cross-reactivity occurs
intraspecifically between various Salmonella spp serovars and Throughout this study, the clinical correlates of infection did
interspecifically between Salmonella spp and various non- not always match serologic results. This may suggest that se-
Salmonella pathogens, such as members of the genus Brucella ropositivity in these cases was primarily an indicator of sub-
or other members of the Enterobacteriaceae. Because neither clinical exposure rather than of previous clinically manifested
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culture nor molecular diagnostics were used in this study, ad- illness. There were 74 participants who were seropositive for
ditional research will be needed to resolve this discrepancy. more than one type of infectious agent and few were seropos-
However, it is interesting to note that although anecdotal evi- itive for up to seven pathogens simultaneously. These findings
dence suggests that international visitors to Georgia often have suggest that a high rate of pathogen exposure is occurring in
diarrheal disease soon after arrival, typhoid fever has not been Georgia without the development of clinical disease in the na-
recently detected in Georgia by active or passive surveillance. tive-born population. A greater understanding of the nature of
these exposures and how they relate to clinical illness and host
Because Salmonella spp have not been extensively charac- immune status will be essential for the advancement of force
terized in Georgia, it is possible that unique or undescribed health protection and public health efforts.

138 | JSOM Volume 18, Edition 2/Summer 2018