Ecology of Cutaneous Leishmaniasis in Sinai: Linking Parasites, Vectors and Hosts

Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 109(3): 299-306, May 2014 299 Ecology of cutaneous leishmaniasis in Sinai: linking parasites, vectors and hosts Abdallah Mohammed Samy1,2/+, Said Abdallah Doha3, Mohamed Amin Kenawy1 1Department of Entomology 3Research and Training Center on Vectors of Diseases, Faculty of Science, Ain Shams University, Abbassia, Cairo, Egypt 2Biodiversity Institute/Department of Ecology and Evolutionary Biology, The University of Kansas, Lawrence, KS, USA Cutaneous leishmaniasis (CL) is a neglected clinical form of public health importance that is quite prevalent in the northern and eastern parts of Egypt. A comprehensive study over seven years (January 2005-December 2011) was conducted to track CL transmission with respect to both sandfly vectors and animal reservoirs. The study identified six sandfly species collected from different districts in North Sinai: Phlebotomus papatasi, Phlebotomus kazeru- ni, Phlebotomus sergenti, Phlebotomus alexandri, Sergentomyia antennata and Sergentomyia clydei. Leishmania (-)-like flagellates were identified in 15 P. papatasi individuals (0.5% of 3,008 dissected females). Rodent populations were sampled in the same districts where sandflies were collected and eight species were identified: Rattus norvegi- cus (n = 39), Rattus rattus frugivorous (n = 13), Rattus rattus alexandrinus (n = 4), Gerbillus pyramidum floweri (n = 38), Gerbillus andersoni (n = 28), Mus musculus (n = 5), Meriones sacramenti (n = 22) and Meriones crassus (n = 10). Thirty-two rodents were found to be positive for Leishmania infection (20.12% of 159 examined rodents). Only Leishmania major was isolated and identified in 100% of the parasite samples. The diversity of both the vector and rodent populations was examined using diversity indices and clustering approaches. Key words: sandfly - Phlebotomus - leishmaniasis - Leishmania major - Sinai - Egypt Cutaneous leishmaniasis (CL) is a neglected clinical of endemicity (Reithinger et al. 2007). The ability to dis- form that is highly prevalent in the northern and east- tinguish between Leishmania species is, therefore, crucial ern parts of Egypt. Leishmania major and Leishmania for correct diagnosis, prognosis, treatment and control tropica circulate in Sinai (Shehata et al. 2009). L. major measures. In Egypt, however, little is known about para- is known to be transmitted by the sandfly Phlebotomus site genotypes (Shehata et al. 1988). Recent studies have papatasi; however, no vector information is available depended on internal transcribed spacer (ITS)-1 sequenc- in the sole report documenting L. tropica from Egypt es to differentiate between imported and autochthonous (Shehata et al. 2009). A new focus of CL was identified infections (Jacobson et al. 2003); other methods can be on the border between Egypt and neighbouring Palestine used to complement ITS-1 sequences, such as microsat- and Israel (Jacobson 2003, Nasereddin et al. 2008). The ellites and kinetoplastid DNA (Schwenkenbecher et al. presence of CL caused by L. tropica remains unclear 2006). Epidemics of leishmaniasis are known to occur with regard to the two scenarios described by Shehata in many foci throughout the world (Seaman et al. 1996, et al. (2009): that historical difficulties in distinguishing Rodríguez-Barraquer et al. 2008, Wang et al. 2010). None- L. major from L. tropica (Jacobson 2003) have masked theless, molecular studies to date have not often taken ad- the presence of L. tropica in past studies vs. that recent vantage of phylogenetic or population genetic approaches incursion by L. tropica from adjacent endemic regions is for data analysis in Middle Eastern countries (Tibayrenc responsible for this species’ recent detection. 2005, Nasereddin et al. 2008), even though successful ex- Leishmaniasis diagnosis is a major challenge due to its amples are available from other locations (Katakura 2009, diverse clinical manifestations, which make the concrete Miranda et al. 2009). Consequently, CL public health im- diagnosis of present and past cases difficult. However, pacts have been underestimated, as a substantial number differential diagnosis is important because other diseases of cases go unrecorded: approximately 1.5-2 million new with a similar clinical spectrum [e.g., leprosy, skin can- cases are estimated to occur annually, but only 600,000 cer and tuberculosis for CL, malaria and schistosomiasis are officially declared (WHO 2008). for visceral leishmaniasis (VL)] often co-occur in areas Leishmaniasis dynamics have changed in response to environmental, demographic and human behavioural factors (Campbell-Lendrum et al. 2001). The response of leishmaniasis to environmental changes may result from a change in the geographic distribution of the potential vectors/animal reservoir, either by the identification doi: 10.1590/0074-0276130426 of new habitats or by range shifts for the same species Financial support: RTC/Vectors of Diseases, Department of Ento- (Parmesan 2006). In Egypt, however, CL cases are still mology/Ain Shams University underestimated due to the Bedouin traditions of prevent- + Corresponding author: [email protected] Received 2 September 2013 ing females from visiting clinics and their dependence on Accepted 19 February 2014 routine heat therapy for the treatment of CL (Samy 2009). online | memorias.ioc.fiocruz.br 300 Leishmaniasis in North Sinai, Egypt • Abdallah Mohammed Samy et al. Here, we report our findings from a comprehensive study tion sites were chosen to represent the most productive conducted over seven years to track the CL transmission ones for fly capture based on our preliminary studies cycle. Our findings suggest the continuous circulation of conducted in different sites of Sinai. The traps were set L. major in Sinai and identify both the vector(s) and ani- before sunset and recovered the next morning. The re- mal reservoir(s), providing new insight into the ecology covered ST were placed in labelled plastic bags, trans- of CL and disease transmission in Egypt. ported to a temporary field laboratory and then sent to MATERIALS AND METHODS the Research and Training Centre Laboratory (RTC) of Ain Shams University, Cairo for processing. Dead flies Study sites - North Sinai is located in the northeast- were stored in 70% alcohol for species identification. ern part of Egypt (30.5ºN 33.6ºE), marking the point of The live flies captured by the CDC traps were collected connection between Asia and Africa. North Sinai is bor- with a mechanical aspirator and dissected in saline with dered by the Gulf of Suez, the Red Sea and the Mediter- 50 U/mL of amikacin sulphate on a glass slide. The di- ranean Sea and is inhabited mainly by Bedouins. The gestive tract was examined under an optical microscope regions comprise the following districts: El-Hassana, with 400X magnification to identify flies harbouring Beer El Abd, Nekhel, Sheikh Zuweid, Beer Lehfen and parasites in their gut and for species identification via Rafah (Fig. 1). The study sites were selected based on the morphological keys (Lane 1986). The identification of distribution of CL cases in Sinai to understand the po- Phlebotomus sergenti followed Depaquit et al. (1998). tential role of both the sandfly and rodent in the dynam- Female digestive tracts that had flagellates were trans- ics of Leishmania transmission (Samy 2009, Ministry of ferred to an Eppendorf tube with saline containing 50 U/ Health of Egypt, unpublished observations). These dis- mL of amikacin sulphate and then inoculated into Novy tricts have diverse geographic and demographic charac- Mac Neal Nicolle (NNN) culture medium. teristics and their “crossroads” nature and environmental changes may create new potential risks for disease Rodent trapping and processing - Rodents were transmission. The weather in North Sinai is character- trapped using wire-box rodent traps (Morsy et al. 1992, ised as hot and dry, with marked differences in tempera- Hamadto et al. 2007) (Fig. 2A) placed adjacent to out- ture between day and night. Dramatic weather-related door and indoor rodent burrows. Each district was rep- resented by five-eight collection sites where 10-18 traps changes, as presented by the annual averages of envi- each were used; the traps were set before sunset and re- ronmental factors during the study period from January covered the next morning. The rodents were identified 2005-December 2011, are listed in Supplementary data using regional taxonomic keys (Osborn & Helmy 1980) and some habitats are illustrated in Fig. 2. and then transported to the Ain Shams animal facility Sandfly collection and processing - Sandfly collec- where they were maintained for at least six months to tion was carried out using sticky paper traps and CDC observe the development of any characteristic Leishma- light traps (LT) (John W Hock, Gainesville, FL, USA) nia lesions. Full-thickness punch-biopsies were removed for eight nights/year. Five collection sites were selected from the border of suspected lesions and processed for randomly to represent each district in the study; 10 CDC parasite isolation in NNN medium. Giemsa-stained im- LT and 50 sticky traps (ST) were used for each study pression smears were also performed for the lesions and district (2 CDC and 10 ST/collection site). The collec- Fig. 2: sampling localities showing different habitat types. A: wire- Fig. 1: regional and local map of the study sites in North Sinai. The box rodent traps used during the study with an individual rodent col- six districts of North Sinai are

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