|
|
Letter
Serologic Evidence of Human
Granulocytic Ehrlichiosis, Greece
To the Editor: Human granulocytic ehrlichiosis (HGE), a tickborne
infectious disease, was first described in 1994 (1).
Several cases have been reported in the United States; reports of acute
cases in Europe have been rare, although European serosurveys of the prevalence
of antibodies to the HGE agent have been conducted (2–4).
No similar serosurvey has been conducted in Greece, although Ixodes
ricinus, thought to be the principal tick vector in Europe (5),
is present in northern Greece (6). Lyme disease, which
is transmitted by the same tick, has never been reported, and the seroprevalence
of Lyme borreliosis in Greece is very low (7).
We examined sera of 300 persons (100 men and 200 women) ages 15–78 years
(mean age ± standard deviation 52.7±18.0 years), which were collected
at six county hospitals in northern Greece and sent to our laboratory
from April to October 2000. The participants were mostly farmers, all
of whom lived in rural areas of northern Greece. All participants were
healthy and had been hospitalized for routine blood tests. Each patient
completed a questionnaire about medical history. The selected patients
had no known history of rickettsiosis and reported no febrile or influenza-like
illness during the past 6 months. Each participant provided oral consent
for the serum to be used for detecting antibodies against several infectious
agents related to zoonoses. The following information was recorded for
each participant: age, sex, occupation, and area of residence.
Serum samples were tested by indirect immunofluorescence (IFA) with commercially
available antigen (Focus Technologies, Cypress, California), which uses
HGE-1–infected HL60 cells. Titers >64 were considered positive.
All sera were also tested for Rickettsia conorii, R. typhi,
Coxiella burneti, and Ehrlichia chaffeensis by IFA and for
Borrelia burgdorferi by enzyme-linked immunosorbent assay and Western
blot. Sera that reacted positively to more than one of these agents were
excluded. Biostatistical analysis was performed by using the statistical
package SPSS for Windows 10.0.1 (Standard version, SPSS Inc., Chicago,
IL).
The overall prevalence of antibodies to the HGE agent was 7.3% (8.0%
for men and 7.0% for women). No statistically significant differences
were observed in the prevalence of antibodies in the six prefecture hospitals.
Participants had no statistically significant differences in sex or age.
Antibody titers to HGE were low (of 22 positive sera, 12 had titers >64
and 10 had titers >128).
Several serosurveys of the prevalence of antibodies to the HGE agent
have been conducted across Europe in both healthy persons and patients
with suspected or confirmed Lyme borreliosis (2,3,8).
Since cases of B. burgdorferi infection are rare or nonexistent
in Greece and the seroprevalence of Lyme borreliosis is very low, we selected
as participants 300 healthy farmers who lived in rural areas. These persons
compose a group at high risk for exposure to tick bites and therefore
to I. ricinus. Our prevalence is higher than those observed in
Bulgaria (2.9%) and Germany (1.9%) (2,3). This finding
could be attributed to the fact that the prevalence in these countries
was based on blood donors, unlike our survey. However, our prevalence
is substantially lower than that in Slovenia, where 15.4% of the examined
population had detectable antibodies to the HGE agent and several cases
of HE have been confirmed (4). Our observation that no
significant differences occurred in the prevalence of antibodies to the
HGE agent in the six prefectures studied could be explained by the fact
that these districts are small, with little variation in environmental
and climatic conditions. Even though the antibody titers to the HGE agent
were low in our survey, they suggest infection at an undetermined time
(9). Seven of our sera were antibody positive to both
the HGE agent and at least one other rickettsial agent or B. burgdorferi.
This fact, which has been observed elsewhere (9), may
result from coinfection or crossreaction. These sera were excluded. Our
data suggest the possibility that HGE cases exist in Greece. Since such
cases have been not been reported to date, they are likely underdiagnosed.
Further research is needed to clarify the presence of the HGE agent in
Greece.
Stella Alexiou Daniel, Katerina Manika, Malamatenia Arvanitidou, Eudoxia
Diza, Nikolaos Symeonidis, Antonis Antoniadis
Aristotelian University of Thessaloniki, Thessaloniki, Greece
References
- Chen SM, Dumler JS, Bakken JS, Walker DH. Identification
of a granulocytotropic Ehrlichia species as the etiologic agent
of human disease. J Clin Microbiol 1994;32:589–95.
- Christova IS, Dumler JS. Human
granulocytic ehrlichiosis in Bulgaria. Am J Trop Med Hyg 1999;60:58–61.
- Fingerle V, Goodman JL, Johnson RC, Kurtti TJ, Munderloh UG, Wilske
B. Epidemiological
aspects of human granulocytic ehrlichiosis in southern Germany.
Wien Klin Wochenschr 1999;111:1000–4.
- Cizman M, Avsic-Zupanc T, Petrovec M, Ruzic-Sabljic E, Pokorn M.
Seroprevalence of ehrlichiosis, Lyme borreliosis and tick-borne encephalitis
infections in children and young adults in Slovenia. Wien Klin Wochenschr
2000; 112:842–5.
- Petrovec M, Sumner JW, Nicholson WL, Childs JE, Strle F, Barlic J,
et al. Identity
of ehrlichial DNA sequences derived from Ixodes ricinus ticks
with those obtained from patients with human granulocytic ehrlichiosis
in Slovenia. J Clin Microbiol 1999;37:209–10.
- Papadopoulos B, Morel PC, Aeschlimann A. Ticks
of domestic animals in the Macedonia region of Greece. Vet Parasitol
1996;63:25–40.
- Stamouli M, Totos G, Braun HB, Michel G, Gizaris V. Very
low seroprevalence of Lyme borreliosis in young Greek males. Eur
J Epidemiol 2000;16: 495–6.
- Skarphedinsson S, Sogaard P, Pedersen C. Seroprevalence
of human granulocytic ehrlichiosis in high-risk groups in Denmark.
Scand J Infect Dis 2001;33:206–10.
- Comer JA, Nicholson WL, Olson JG, Childs JE. Serological
testing for human granulocytic ehrlichiosis at a national referral center.
J Clin Microbiol 1999;37:558–64.
|
