Trypanosomes and Gut Microbiota Interactions in Triatomine bugs and Tsetse Flies: A vectorial perspective.

Triatomines (kissing bugs) and tsetse flies (genus: Glossina) are natural vectors of Trypanosoma cruzi and Trypanosoma brucei, respectively. T. cruzi is the causative agent of Chagas disease, endemic in Latin America, while T. brucei causes African sleeping sickness disease in sub-Saharan Africa. Both triatomines and tsetse flies are host to a diverse community of gut microbiota that co-exist with the parasites in the gut. Evidence has shown that the gut microbiota of both vectors plays a key role in parasite development and transmission. However, knowledge on the mechanism involved in parasite-microbiota interaction remains limited and scanty. Here, we attempt to analyse Trypanosoma spp. and gut microbiota interactions in tsetse flies and triatomines, with a focus on understanding the possible mechanisms involved by reviewing published articles on the subject. We report that interactions between Trypanosoma spp. and gut microbiota can be both direct and indirect. In direct interactions, the gut microbiota directly affects the parasite via the formation of biofilms and the production of anti-parasitic molecules, while on the other hand, Trypanosoma spp. produces antimicrobial proteins to regulate gut microbiota of the vector. In indirect interactions, the parasite and gut bacteria affect each other through host vector-activated processes such as immunity and metabolism. Although we are beginning to understand how gut microbiota interacts with the Trypanosoma parasites, there is still a need for further studies on functional role of gut microbiota in parasite development to maximize the use of symbiotic bacteria in vector and parasite control.

Fauna, Seasonal Activity, and Altitudinal Distribution of Phlebotomine Sand Flies (Diptera: Psychodidae) in Leishmaniasis Endemic Area, Aydin Mountains, and Surroundings in Western Turkey

Objective: Human and canine leishmaniasis (CanL) are endemic in Turkey, and cutaneous leishmaniasis (CL) is a primary public health problem among vector-borne diseases, with 1500-2000 autochthonous cases per year. In this study, we aimed to perform a comprehensive entomological survey, including the detection of sand fly fauna, seasonal activity, and altitudinal distribution, together with the ecological features of Aydin Mountains and their surroundings that are endemic areas for CL caused by Leishmania tropica and CanL caused by L. infantum MON-1. Methods: The survey was carried out from June 2009 to July 2010. Ten localities with different altitudes were selected. Sand fly collection was done every 15 days in July and August when sand flies are most active and every 30 days between September and June (14 months, 16 samplings) using CDC light traps and sticky traps. During the collection, the temperature, humidity, and ecological and environmental features were recorded. Sand fly specimens were dissected and identified at species level using written keys. Results: A total of 6712 sand fly specimens (3268 females and 3444 males) were collected from 10 localities throughout all study periods. Species identification revealed that nine and three species belonging to Phlebotomus (P. major s.l. 30.38%, P. tobbi 22.93%, P. papatasi 5.88%, P. sergenti s.l. 4.51%, P. alexandri 4.26%, P. simici 3.50%, P. burneyi 0.63%, P. brevis 0.45%, and Transphlebotomus spp. 0.28%) and Sergentomyia (S. dentata 23.17%, S. minuta 2.43%, and S. antennata 1.58%) were found, respectively. The seasonal activities of these 12 sand fly species were determined, and P. major s.l. and P. tobbi, which were probable vectors of VL and CanL, were present in the study area. P. sergenti s.l., a probable vector of CL, was also found in the region and was active for seven months between April and October. P. sergenti s.l. was found in the 400-600 m altitude in July, while P. major and P. tobbi were found in high densities in the 200-400 m altitude in September. Conclusion: Our results showed that leishmaniasis vectors are present in different altitudes in the Aydin mountains and surroundings. The findings revealed the time intervals of parasite transmission in the area and the period of applying protective measures, such as insecticide application.

Host-Parasite Interactions: Regulation of Leishmania Infection in Sand Fly.

PURPOSE: Sand flies are the only proven vectors of leishmaniases, a tropical neglected disease endemic in at least 92 countries. Vector-parasite interactions play a significant role in vector-borne disease transmission. There are various bottlenecks to Leishmania colonization of the sand fly midgut. Such bottlenecks include the production of innate immune-related molecules, digestive proteases, parasite impermeable peritrophic membrane, and resident gut microbiota. These barriers determine the parasite load transmitted and, consequently, the disease outcome in mammalian host. Therefore, it is important to understand the molecular responses of both sand fly and Leishmania during infection. METHOD: Here, we reviewed the published literature on sand fly-Leishmania interactions bringing together earlier and current findings to highlight new developments and research gaps in the field. CONCLUSION: Recent research studies on sand fly-Leishmania interaction have revealed contrasting observations to past studies. However, how Leishmania parasites evade the sand fly immune response still needs further research. Sand fly response to Leishmania infection can be best understood by analyzing its tissue transcriptome. Better characterization of the role of midgut components could be a game changer in development of transmission-blocking strategies for leishmaniasis.

Determination of sand fly fauna and molecular detection of Leishmania in sand flies in Antalya Province, Southern Turkey.

Visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) are diseases transmitted by infected female sand flies. Since the eradication of malaria in Turkey, CL is the main vector-borne disease in the country, with more than 2000 cases per year, making it a significant public health problem. The aims of this study were to carry out an entomological survey in Antalya Province, an endemic area for CL in the Mediterranean Region of Turkey, to identify sand fly fauna and to screen female specimens for the presence of Leishmania parasites (Leishmania infantum, L. tropica, L. major, and L. donovani) using molecular analysis. Sand flies were collected in 42 localities of seven districts in Antalya Province using CDC miniature light traps in two different periods, June 2012 and September 2013. The specimens were kept in 96% ethanol until the dissection was done. The head and genitalia of the specimens were cut for preparing individual slides for species identification. The rest of the body of female specimens was kept separately. The specimens were identified at the species level, and 27 pools were generated according to the locations and species for screening the presence of Leishmania. A commercial kit was used for DNA extractions. Real-time and conventional polymerase chain reaction (PCR) targeting the internal transcribed spacer region (ITS1) were then performed. In total, 1306 specimens comprising nine species belonging to the Phlebotomus genus were collected in the study region, with Phlebotomus neglectus/syriacus (38.82%) the most abundant, followed by P. alexandri (21.67%) and P. tobbi (20.44%). In the 27 pools, Leishmania infantum DNA was detected in four pools containing P. neglectus/syriacus and one pool containing P. tobbi. In conclusion, the sand fly fauna in the Antalya Province is diverse. The probable vector sand fly species are P. neglectus/syriacus and P. tobbi with high dominance (59.26%), which indicates a high risk of CL transmission. The data presented here may help to shed more light on the transmission cycles of the Leishmania parasite in this CL endemic area.

Entomological Survey of the Sand Fly Fauna of Kayseri Province: Focus on Visceral and Cutaneous Leishmaniasis in Central Anatolia, Turkey

Objective: In Turkey, leishmaniasis occurs in two clinical forms: cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL). CL has been reported mainly from south-eastern Anatolia and the eastern part of the Mediterranean region, whereas VL is sporadic in almost all geographical regions of Turkey. Both clinical forms of the disease have been recorded in Kayseri province for decades, but no study has been conducted on the sand fly fauna in this area. Therefore, we determine the species composition and population dynamics of sand flies prevalent in Kayseri province and identify possible vector species. Methods: Data related to the recent locations of CL and VL cases were obtained from the Ministry of Health, and sand flies were collected in 14 localities of different districts using CDC light traps. The specimens were transferred to the laboratory in 70% ethanol, and morphological identification to the species level was performed using previously written keys. Results: A total of 1,636 sand fly specimens were collected. Morphological identification revealed eight species of the genus Phlebotomus (P. perfiliewi s.l., P. halepensis, P. simici, P. major s.l., P. papatasi, P. tobbi, P. sergenti and P. mascittii) and one species of the genus Sergentomyia (S. dentata). Among all specimens, members of subgenus Adlerius (54.58%) formed the dominant group, followed by the subgenus Larroussius (43.76%). Conclusion: Our results showed that P. halepensis, belonging to subgenus Adlerius, and P. perfiliewi, belonging to the subgenus, are probable vectors of cutaneous and VL in the province, respectively.

Investigation of Intestinal Parasites in Living Nursing Home

Objective: Intestinal infections are common in the elderly, presented with atypical symptoms and may be the cause of mortality with a more severe clinical manifestation. The weakening of cellular and humoral immunity by aging affects the intestinal flora and increases the risk of infection in the presence of chronic diseases. The aim of this study was to investigate the presence of possible parasitic agents in the intestinal system of ≥65-year-old nursing home residents through fecal examination, and to determine the demographic features (age and gender) of this elderly group. Methods: A total of 82 stool samples were examined (100x, 40x) with saline and iodine preparations, formol-ethyl acetate concentration process, trichrome and modified Erlich Ziehl Neelsen stained preparations. Results: One or more parasitological agents were detected in 17 (20.7%) of the 82 stool samples examined. The most common agent was Blastocystis spp. (13.4%), followed by Cryptosporidium spp. (2.4%) and Dientamoeba fragilis (2.4%). Conclusion: In this study, it was determined that attention should be given to elderly population with regard to intestinal parasitic infections. Because of changes in the immune system, more opportunistic factors could be detected. More frequent screening in public areas such as nursing homes is important for preventing infections.

Vector and reservoir surveillance study in a canine and human leishmaniasis endemic area in most western part of Turkey, Karaburun.

Leishmaniasis is an arthropod borne disease that is endemic in 102 countries and one and half million new cases are reported each year. Sand flies are the one and only proven vectors of the disease and dogs are the main reservoirs in urban areas. Karaburun peninsula is located in most western part of Turkey and is reported to be an endemic area for human and canine leishmaniasis. The most recent study was undertaken more than 15 years ago in The peninsula and no clear data available for vectors or reservoirs. Thus, we aimed to update the information regarding sand fly diversity, infection status of reservoirs and vectors in the study area. Sand flies were collected using CDC light traps at 13 different sites of Karaburun and species identification was made using previously published keys. Monospecific pools were generated using midguts with blood retention and were screened for the presence of Leishmania spp. DNA by molecular techniques. A non-invasive conjunctival swab sampling was performed to identify the infection status among reservoirs and species typing of the causative agent was also undertaken using ITS1 PCR. Three out of 30 pools were found positive for Leishmania infantum that were generated using guts of Phlebotomus tobbi (n:36). Among all sampled dogs (44) and cats (19), 11 and one of them were found positive for L. infantum, respectively. There was a decrease in the number of P. papatasi during the study period, while increase was observed in the number of P. tobbi. The presence of proven vectors and reservoirs as well as Leishmania DNA in cats was shown in the present study. Sand fly fauna is updated and Leishmania DNA presence in cats was reported in the study area for the first time.

Eustigmaeus johnstoni Zhang - Gerson (Acari: Stigmaeidae) a Parasitic Mite Species Detected in Phlebotomus papatasi (Diptera: Psychodidae) Specimens Collected from Aydin, Turkey.

OBJECTIVE: We aimed to report the presence of the parasitic mite Eustigmaeus johnstoni Zhang - Gerson (E. johnstoni) on the sand fly species Phlebotomus papatasi (P. papatasi) collected in Aydin province, Turkey. METHODS: Sand flies were collected from nature by CDC light traps in Nazilli town in Aydin province and were separated according to collection localities. Head and genital areas were cut and mounted for species identification, and midgut contents were checked for the possible presence of Leishmania parasites under a light microscope. Mites detected in sand flies were diagnosed on the species level based on the literature. RESULTS: A total of 360 female and 378 male sand flies were caught. During dissection and preparation, two female E. johnstoni parasitic mite specimens belonging to the genus Eustigmaeus were detected on the abdominal pleura of P. papatasi specimens. CONCLUSION: To our knowledge, this is the first study to report the presence E. johnstoni on P. papatasi in Turkey. Previous studies showing the relationship between parasitic mites and sand flies have indicated that this relationship is not accidental. More studies are needed to understand this relationship for obtaining more detailed information.

[An epidemiological study on canine leishmaniasis (CanL) and sand flies in Northern Cyprus]. / Kuzey Kibris'ta Kanin Leishmaniasis ve Kum Sineklerinin Epidemiyolojisi.

OBJECTIVE: In this study, the investigation on the prevalence of canine leishmaniasis (CanL) and sand fly species incriminated as potential vectors of leishmaniasis in the northern part of the Cyprus were aimed. METHODS: This research was conducted in two periods; 2004 and 2012. Serological (IFAT and rK39) and molecular (PCR) tests were performed on 83 dog blood samples during the 2004 survey. PCR was performed using primers 13A/13B targeting kinetoplastid minicircle constant region. Genomic Nested-PCR was applied using R221/R332 and R323/333 primers for 5 clinically suspected dog samples in 2012. Sand flies were collected from the Lapithos town and Kyreniae province using CDC light traps and midgut dissection was done for the presence of Leishmania parasites during the 2012 survey. RESULTS: Three (3.61%) out of 83 dogs were found to be positive for CanL in 2004, while 3 out of 5 clinically suspected dogs were positive in 2012. In total 296 female sand flies were dissected and 9 species belonging to Phlebotomus and Sergentomyia genera were determined. No promastigote was found in the dissected females. CONCLUSION: The results obtained in two different periods showed that the importance and risk of canine disease are increasing in the northern Cyprus and further studies should be performed in northern Cyprus for determining the incidence of canine and human leishmaniasis.