Sandflies (Diptera: Psychodidae) in the Bar area of Montenegro ...

1 downloads 0 Views 4MB Size Report
Oct 8, 2002 - For many years, Montenegro (Yugoslavia) ... Montenegro, the coastal district of Bar, was ..... B. Chaniotis (Faculty of Medicine, University.
Sroe02-0?O'1 Allnals of Tropical Medicine & Parasirology, Vol. 97, No.2, 193-197 (2003) afler allogeneic l.on JOllrnal of Masera, G., ii, G. (1985). ren with aClllC IPY· JOllrnal of ). Clinical and leficiency virus ,fused patients ialysis. Leballese ., !\-tokhbat, J., I and HTLV-I1 I and high-risk n, 45, 29- 3l. , Haraki, 5., n, R. (2002). ~patilis-G-virus

cs. Alltlals of , 197-202. cco, F. (1991). :sponse during 'pressed HCV ,50,52-60. 'dairy, S. & fami-HTLV-I non-Hodgkin's 10,626-628. Tuke, P. W., $: Garson, J. A. . and viraemia .ophilia. Bloirish , Zhang, L. Q., 1992). Use of lssays 10 deter\'irus infeclion rus inactivated :rish JOllrnal of Reddy, K. R., . Collaborative IS geno[}'Pes in ,ogenicily, and als of [memal

Sandflies (Diptera: Psychodidae) in the Bar area of Montenegro (Yugoslavia) v. IVOVIC*, M. IVOVICt and Z. MISCEVIC* *Laboratory ofAtledical Arachno-elllomology, Institute for Atledical Research, P. O. Box 102, 11129 Belgrade, Yugoslavia tNalllral History Museum, P.O. Box 401, 11000 Belgrade, Yugoslavia Received 8 October 2002, Accepted 21 November 2002

The spccies and ecology of sandflies present in Ihe coastal district of Bar, which lies in I\'lontenegro, an cndemic focus of \'isceral leishmaniasis (VL), were investigated in 1996-1999. A mean of 10 cases of VL and a greater number of viral infections (some of which are altributed to pathogens transmitted by sandfties) are diagnosed each year in this district. Phlebotomus paparasi, P. pe1jili/!'lui, P. robbi, P. mglecrus and Sergemomyia minuUl were collected, P. pe1jiliewi being recorded for the first time in Montenegro. The ecology and distribution of each of these five species are described and Iheir role, if any, in the transmission of Leishmania to humans is discussed.

For many years, Montenegro (Yugoslavia) has been a major endemic focus of visceral leishmaniasis (VL). In consequence, the region has been the subject of extensive research, both on the prevalence and distribution of the VL and on the species of phlebotomine sandfl.y that act as vectors of the leishmaniaI parasites involved (Simic et aI., 1950; Zivkovic and Miscevic, 1970). In 1996, concern was expressed that the VL in one area of Montenegro, the coastal district of Bar, was becoming a particular problem. According to the medical records of hospitals in Bar and Belgrade, annual incidence ofVL in this district had increased from a mean of just three cases before 1970 to one of 10 cases between 1986 and 1996 (unpubl. obs.). The aim of the present, 4-year study was to explore the species and ecology of the 'lIevidi' (the 'invisible ones', as sandflies are called by Reprinr requests to: V. Ivovic, Department of Clinical Bacteriology, Parasitology, Zoonoses and Geographical Medicine, WHO Collaborating Cenrre for Research and Training in Mediterranean Zoonoses, School of Medicine, Universiry of Crcle, P.O. Box 1393, 71409 Heraklion, Greece. E-mail: [email protected]; fax: +302810394740. -,I::' 2003 The Liverpool School of Tropical Medicine

DOl: 10.1179/000349803235001543

the local residents) that occurred in this district, and try to relate the findings to the epidemiology of the VL (and sandflytransmitted viral infections) in the area.

MATERIALS AND METHODS Study Area The 505 km 2 of land that fonn the district of Bar, in southern Montenegro, are outlined by 46 km of the Adriatic coast to the south-west, the Albanian border to the'.east and the mountain ridges of Sutorman and Rumija to the north. Although the coastline is densely populated, with many villages and tourist resorts, there are only sparsely distnbuted villages on the karst plains and hills further north. The coastal city of Bar (42 c 05'N, 19°06'E), the largest Montenegrin port, was almost completely destroyed by an earthquake in 1971 but was rebuilt and has become a modem cultural and economic centre. For the present study, sandfl.ies were collected in four sites: the village of Zagradje (near the city of Sutomore) and in the areas of Stari Bar, Rap and Bartula.

194

IVOVIC ET AL.

Collection and Identification of Sandflies In each of 4 years (1996-1999), adult sandflies were collected, on alternate mornings (between 08.00 and 10.00 hours) during their seasonal period of peak activity (1 July31 August), from 10 houses in each study site. Sandflies in the bedrooms and living rooms of the study houses were collected, by hand, using test-tubes, each of which contained a wad of ether-soaked cotton wool (covered with a circle of filter paper to stop the flies becoming tangled in the cotton). Such tubes were also used to collect flies landing on the external walls of houses, close to outside lights; in an attempt to determine at what time of night their activity peaked, sandflies were collected from such walls from dusk until dawn and pooled at 30-min intervals. The tube-collected flies were preserved in 80% ethanol. Sticky traps, made ofwriring paper (either A4 or measuring 120 cm x 80 em) smeared with motor oil and often folded into tubes and cones to fit the particular microhabitat being sampled, were also used to collect sandflies. The traps were set within the settlements at the four study sites (in animal quarters and outbuildings) and outside of them (within walls, in treeholes in the olive groves, in the open, surrounding, phrygana-type scrubland, and in rodent or lizard burrows or on rodent runs in the scrubland). Each trap was checked for sandflies and replaced with a new trap every 6 days, in the July and August of each study year. The sandflies trapped on the sticky paper were removed with watercolour

TABLE.

brushes, fixed in 96% alcohol for 24 h, and finally stored in test tubes containing 80% ethanol. For identification to sex and species, each sandfly was cleared in lacto-phenol, mounted permanently in a drop of Canada balsam on a microscope slide, and compared against the relevant taxonomic keys (Theodor, 1958; Perfiliev, 1966; Lewis, 1982).

RESULTS During the 4-year study, 4770 sandflies (2397 males and 2373 females) were collected from all of the localities investigated. Of the collected females, 1043 were unfed, 687 fed but not gravid, and 643 gravid (see Table). The most frequently collected species was Phlebotomus 11eglectlls (accounting for 60% of all the sandflies collected), followed by P. tobbi (16%), Sergelltomyia milluta (12%), P. papawsi (II %) and, finally, P. perfiliewi (1 %). Phlebotomus papawsi appeared both synanthropic and markedly anthropophilic; no flies of this species were collected outside of human settlements, and all of the P. papawsi caught in two of the four study sites (Zagradje and Stari Bar) were collected, by hand, from dark corners of bedrooms and living rooms. The numbers of this species varied seasonally even within the annual, 2-month sampling period, generally being most abundant at the beginning of July, with, in 1996 and ".1997, a smaller peak in the second week of August. In 1998, when the summer was particularly

The sex racio arid categories offemale sa'ldjiies collemd in Bar dim;cl

0/0 of females

Species PhlebotomllS ,teglecllls P. IObbi P. paparwi P. perfiliewi Sergemomyia minllta

% of collection female

Unfed

Fed but not gravid

Gravid

46 60 67 70 37

44 56 21 46

26

16 64 22

55

19

30 28 15 32 26

SANDFUES IN MONTENEGRO

II for 24 h, and ontaining 80%

,d species, each tenol, mounted lada balsam on npared against lbcodor, 1958;

sandtlies (2397 vere collected tigated. Of the unfed, 687 fed id (see Table). :d species was :ing for 60% of Iwed by P. cobbi !%), P. papawsi Qi (I %). ed both synan'opophiJic; no ;ted outside of the P. paparasi sites (Zagradje by hand, from I living rooms. .ried seasonally Jnth sampling bundant at the 196 and 1997, eck of August. as particularly

hot and dry, the first peak was prolonged and numbers did not fall until mid-August. In contrast to the peridomestic P. papalasi, most of the P. negleetus were collected on the illuminated outside walls of houses and on sticky traps set in cracks and crevices of supporting stonewalls, in the hollows of olive trees, in the open, surrounding scrubland, and in the burrows of rodents living in such scrubland. The numbers of P. neg/eetus caught peaked both seasonally (in the first and second weeks of August) and, on the external walls, at a panicular time of night (22.00-23.00 hours). The relatively rare P. perfiliewi was only found very sporadically, mostly close to lights on the outside walls of houses. Several were found indoors but only two specimens were collected on sticky traps placed outside of the settlements (both in hollows of olive trees). None was found in any rodent burrow. The numbers of this species peaked in the first half of August and, within each night'S collection from illuminated walls, between 22.30 and 23.00 hours. Most of the P. tobbi (the second most abundant species collected) were caught either on illuminated external walls (with peak activity between 22.00 and 22.30 hours) or on sticky traps set within the settlements studied, although 20% were caught indoors. lvlany of the S. minuta collected also came from illuminated walls (with peak activity between 22.30 and 23.00 hours) but a similar number came from sticky traps placed in rodent and lizard burrows outside of the settlements; relatively few were collected indoors. DISCUSSION

j

Gravid 30

28 15

32 26

The summer climate of Bar district, which is characteristic of much of the Adriatic coast (with temperatures of25-30°C, high relative humidities and occasional summer showers), permits large populations of adult sandflies [0 develop. As a result of the catastrophic earthquake that hit the area in 1971, there are still many ruined houses and toppled walls

195

in the area and these provide numerous resting (and, perhaps, breeding) sites for the flies. The results of relatively small-scale studies on the sandflies of Montenegro revealed the presence of just four species: P. papalasi one of the most abundant Palearctic species (Perfiliev, 1966), P. negleetus, P. cobbi and S. minltta (Simic et al., 1950; Zivkovic and Miscevic, 1970). Perhaps not surprisingly, the present results, of a more detailed and extensive investigation, added another species (P. perfiliewi) to this list. Phlebotomus perfiliewi has been found throughout Serbia, but it is most abundant in the south-east, especially in the area between the cities of Nis and Prokuplje, one of the driest regions (Zivkovic and Miscevic, 1972; Zivkovic et af., 1973; Miscevic, 1979). The results of earlier studies of sandfties, in south-eastern Serbia, have shown that P. perfiliewi can act as vectors of several viruses, including those causing 'sandfly fevers' in humans (Gligic et af., 1982, 1983). Zivkovic and Miscevic (1970) surveyed the sandfties of the Adriatic coast from Trogir (near to Split) in the north to Ulcinj (in Bar district, close to the Albanian border) in the south, collecting sandflies from 34 sites in Montenegro and 28 in Dalmatia. The species they caught most often, close to artificial lights and in ruined houses and walls outdoors, was P. neg/eetus, and this species became increasingly predominant in outdoor catches (reaching 85% of the total catch in the area of Sutomore, close to the city of Bar) as the collectors moved south-east along the coast (Zivkovic and Miscevic, 1970). In the present study, P. negleetus was also the most abundant species in the microhabitats investigated outside of the settlements, such as rodent burrows and tree holes in olive groves. Simic el al. (1950) also found this species to be the most abundant in the collections they made outside of human settlements in Montenegro. Significantly, in tenns of human disease, since this species is considered the probable vector of Leishmania infamum (Leger et ai., 1988), P. negfectus made up to 10% of the indoor collections made during the present study.

196

IVOVIC ET AL.

Elsewhere in Yugoslavia, P. negleetus is rarely caught indoors (Miscevic, 1979). It seems possible that the relatively high frequency with which P. negleetus is found inside houses in Bar district may explain, at least in part, why the incidence of human VL (caused by Le. infamum) also appears relatively high in the area. Phlebotomus tobbi, like P. /legleerus, is a member of the subgenus Larroussius, which includes all the vectors of the parasites causing human VL. As, in several Mediterranean countries, P. tobbi often feeds on humans (Leger et al., 1988), it seems that it too may be an important vector of the parasites causing human leishmaniasis. The results of recent studies in Cyprus implicate P. cobbi as a vector species in the eastern part of the Mediterranean basin, where P. negleetus is absent (Leger et a/., 2000). Although Simic et al. (1950) never found P. tobbi indoors, this species represented 6.8% of all the sandflies collected, 20 years later, inside rooms by Zivkovic and MiScevic (1970), and 20% of the sandflies collected indoors in the present study. If the species is a local vector of the parasites causing human leishmaniasis, the apparent increase, over several decades, in the number of P. tobbi caught indoors in the coastal regions of Yugoslavia and the growing incidence of VL in thc same areas may be linked. In conclusion, it secQ1s likely, that, in Bar district, both P. neg/emtS and P. tobbi are vectors transmitting the parasites causing human leishmaniasis. Increascs, over se\'eral decades, in the size of the local populations of these species andlor in the frequency with which flies of thcse species enter rooms may havc led to an increase in the incidence of VL. When sandflies were collected recently from the homes of several clinical cases of VL, almost all (95%) of the total catch was either P. neg/eccllS or P. tobbi (unpubl. obs.). The aims of future research in this region will be to isolate and type the Leishmania parasites present in the sandfly and human populations and reservoir hosts, in order to have a complete picture of the local transmission cycle.

The authors thank Dr B. Chaniotis (Faculty of Medicine, University of Crcte, Greece), for his helpful comments on the manuscript, and S. Roberts (Marine Biology Institute, Heraldion, Crete, Greece) for his contributions to the revision of the text.

ACKNOWLEDGEMENTS.

REFERENCES Gligic, A., Misce\'ic, Z., Tesh, R. 8., Travassos da Rosa, A. & Zivkovic, V. (1982). First isolation of Naples sand fl}' fe\'er virus in Yugosla\·ia. Alikrobiologija, 19, 16i-175. Gligic, A., Tesh, R. n., Miscevic, Z., Travassos da Rosa, A. & Zivkovic, V. (1983). Jug Bogdanovac virus - a new member of the vesicular stomatitis virus serogroup (Rhabdoviridae: Vesiculo\ims) isolated from phlebotomine sand fi:es in Yugoslavia. MikrobiololflJa, 20,9;-105.

Leger, N., Gramiccia, 1"1., Gradoni, L., MaduloLeblond, G., Pesson, B., Ferte, H., Boulanger, N., Killick-Kendrick, R. & Killick-Kcndrick, M. (1988). Isolation and typing of Leishma"ia infa"tulll from Phlebotomus neglccClls on the island of Corfu, Greece. Transactiolls of the Royal Society of Tropical Medici"e ami Hygiene, 82, 419-420. Leger, N., Depaquit, J., Fenc, H., Rioux, J. A.,

Gantier, J. C., Gramiccia, M., Ludovisi, A., Michaelides, A" Christophi, N. & Economides, P. (2000). Phlebotomine sandfiies (Diptera: Psychodidae) of Ihe isle of Cyprus. II. Isolation and typing of Lcishmam'a (Leisll1llallia) ilifalllllm Nicolle, 1908 (zymodeme MON I) from PlUebolrJmllS (Lammssius) tobbiAdler and Thcodor, 1930. Parasite, 7,143-146. Lewis, D. J. (1982). A taxonomic review of the genus Phlebotomus (Diplera, Psychodidae). BlIllctili of the En'tish ,Huselllll (NaCllral His,oo'). Emomology Senes, 45, 171-209. ~ Miscevic, Z. (1979). The Faunistic alld Ecological Swdy of Salld Flies (Diplera, Phlebotomidae) ill Southeastern Serbia, Area ofDobric, with Special Emphasis Oil Feeding Preferences alld Possible Trallsmissio" of Disease-callsi,lg Agems. Ph.D. thesis, University of Belgrade (in

Serbian). Perfiliev, P. P. (1966). Phleboumlidac (Sandfiies). (Fauna of the USSR: Diplera, Vol. 3). Leningrad: Nauka (in Russian). Simic, t., Gvozdeno\;c, M. & KostiC, D. (950). Contribution to the knowledge of phlebolomine sandflies of Yugoslavia. Part II. The phlebotomine sandfly fauna of Montenegro. Voice of the Serbiall Academy of Sciellce: Medical Scit1lce, 2, 2i-31 (in Serbian). TheodoT, O. (1958). Psychodidae - Phlebotominae. In Die Flicgen der Paliiarillischell Region, Vol. 9, ed. Lindner, E. pp. 1-55. Stuttgart: E. Schweizerbart.

SANDFUES IN MONTENEGRO 10rs thank Dr ine, University ful comments berts (Marine :rete, Greece) ion of the text.

I., Travassos da .olation ofNaplcs ·tiknJbiolol.~)a, 19,

:., Travassos da Jug Bogdanovac Ir stomatitis virus :lis) isolated from :a. ,tJikrobiologija, i, L., Madulo· Boulanger, N., rick, .\;1. (1988). I infatlllll1l from f Corfu, Greece. "ropical Medicine • Rioux, J. A., Ludovisi, A., Economides, P. ,ra: Psychodidae) I and typing of Nicolle, 1908 illS (Larrowsills) lile, 7,143-146. ew of the genus · Bullelin of lhe tIlol1lology Series,

Eclll