Rickettsiosis is a vector-borne disease due to Rickettsia spp, an intracellular bacteria causing infections in human and animals. In Tunisia. Rickettsioses are one of the most important vectorial infectious diseases; more than one hundred cases being registered every year. In this context, an epidemiological survey (Multicentric study) was carried out during 2014-2015 in 5 governorates of the North of Tunisia. Suspected patients with febrile, rashes and/or eschar were subjected to a serological test (IFI) and qPCR analyses (skin biopsies). In addition, entomological survey using molecular tools were performed to identify Rickettsia in 2245 ticks infecting domestic animals. Among 40 tested patients, the seroprevalence of Rickettsia was 53.6%. By qPCR, three skin biopsies were infected by R. conorii conorii. Using qPCR, the global prevalence of Rickettsia infection in ticks was 46% with an average bacterial rate of 105 Rickettsia spp/tick. R. conorii was the most prevalent bacteria infecting ticks.

1. Rickettsiosis in Northern Tunisia
Fatma KHROUF1, Youmna M’GHIRBI1, Saba ZOUARI1, Souha BOUGATEF2, Ali BOUATTOUR1
1 Université Tunis El Manar, IPT, LR11IPT03, Service d’entomologie médicale
2. Observatoire Nationale des Maladies nouvelles et émergentes
Introduction
Rickettsiosis are anthropozoonotic vector borne diseases caused by an obligate
intracellular bacteria of Rickettsia genus. These organisms are classically
transmitted to animals (and accidentally to humans) via arthropod vector bites.
In recent years, the re-emergence of these diseases has attracted scientific
attention. Domestic animals are preferential hosts of several ticks (Ixodidae)
that are principal vectors for this disease. Two rickettsial groups, spotted fever
group and typhus group, have been described since the beginning of the 20th
century, and more than 26 species have been described all over the world [1].
In Tunisia, about 200 cases were registered every year in different medical
centers. However, there is scarce information about the epidemiological
situation of rickettsiosis. Our aim was to determine Rickettsia species infected
in suspected patients through a multicentric study and to detect and
characterise Rickettsia species in ticks collected from domestic animals.
Materials and Methods
During our survey (2014-2015), we received human blood and skin biopsies
samples from different hospitals, in addition, ticks infesting domestic animals
(cattle, sheep and goats), were collected from several farms located in 5 cities
(Bizerte, Béja, Tunis, Ariana, Nabeul). DNA extraction was performed from
samples using QIAamp DNA tissue extraction kit to determine rickettsial
infection by molecular (qPCR and IFI) (Figure 1, Map 1). The DNA of ticks and
human samples was tested by qPCR for Rickettsia infection. The amplified
23S-5S intergenic spacer and citrate synthase gene (gltA) of some positive
samples were sequenced to confirm the infection [2] (Figure 2).
Map 1. Sudied area (collection of human samples and ticks)
Using qPCR, the global prevalence of Rickettsia infection in
ticks was 46% with an average bacterial rate of 105 Rickettsia
spp/tick. This prevalence varies according to ticks species ,
season and localities (Map 2).
Figure 2. Target genes
Figure 1. Collection of tick and
Human samples
Results and discussion
Map 2. Rickettsial infection of ticks using qPCR
We first elucidated the important role of tick infesting domestic
animals in the transmission of rickettsial bacteria and as well as a
reservoir of several Rickettsia species. Then, we demonstrated
the importance of the infection rate of Rickettsia in suspected
patients. Thus, we should improve the surveillance of these
vectorial diseases such as Mediterranean Spotted Fever caused
by R. conorii and Typhus caused by R. typhi, in Tunisia.
More investigations in animals and studies on the vectors are
needed to determine the risk zones of such diseases in Tunisia.
Conclusion
1. Parola P, Paddock CD, Socolovschi C, Labruna MB, Mediannikov O, Kernif T, et al. Update on Tick-Borne Rickettsioses around the
World: a Geographic Approach. Clin. Microbiol. Rev. 2013;26:657–702.
2. Khrouf F, M’Ghirbi Y, Znazen A, Ben Jemaa M, Hammami A, Bouattour A. Detection of Rickettsia in Rhipicephalus sanguineus ticks and
Ctenocephalides felis fleas from southeastern Tunisia by reverse line blot assay. J. Clin. Microbiol. 2014;52:268–74.
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annulatus
Hyalomma
excavatum and Hy.
marginatum
Rhipicephalus
turanicus and Rh.
bursa
Ixodes ricinus
R. aeschlimannii R. helveticaR. massiliae R. massiliae
Laboratoire d’Epidémiologie et Microbiologie Vétérinaire
Service d’Entomologie Médicale
Université Tunis El Manar
Institut Pasteur de Tunis
Béja
9%
Bizerte
20%
Nabeul
37%
Tunis
34%
Total of tested patients
IgM IgG
R. conorii R. typhi R. conorii
Réaction croisée
10/4014/40 18/40
40 patients were tested
by IFI and 4 skin biopsies
by qPCR.
Three skin biopsies were
positives against R.
conorii
The seroprevalence of
Rickettsia infection in
suspected patients
was 53.6%
Finance