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.

Bibliography

Boophilus annulatus

Hyalomma excavatum and Hy.

marginatum

Rhipicephalus turanicus and Rh.

bursa

Ixodes ricinus

R. aeschlimannii R. helvetica R. 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

10/40 14/40 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