INTRODUCTION
Phlebotominae sandflies (Diptera: Psychodidae) are biologic and proven vectors of human leishmaniases across the world1–2. These insects are also capable of transmitting some other pathogens to human such as Bar- tonella spp—the agent of bartonellosis (Carrion’s dis- ease or Oroya fever), papatasi fever virus (family Bunyaviridae, genus Phlebovirus), Toscana virus, Chagres, Punta Toro, and Flaviviruses, Orbiviruses, Vesiculoviruses etc2–3. The phlebotominae sandflies of the subgenus Adlerius are well-known vectors for all types of visceral and cutaneous leishmaniasis (CL) in the Old World countries such as Iran2. Among >800 species of these insects, only 98 species have role in disease transmission to human, including 42
Phlebotomus species in the Old World and 56 species of the Lutzomyia genus in the New World1. Sandflies in- habit in human dwellings, stables, pet shelters, cracks on walls and cliffs, natural caves of mountainous areas, ro- dent burrows, fallen and decaying leaves in forests floor etc4. They have a wide geographical distribution ranging from Australia, through the Indian subcontinent to Cen- tral Asia, and Mediterranean countries in Europe, Africa and America5.
The sandfly vector species, P. papatasi is reported as the main vector of Leishmania major species in many countries such as Uzbekistan, Turkmenistan, Azerbaijan, Saudi Arabia, Jordan, Tunisia, Morocco and Iran6. This species is also recognized as the vector of L. arabica in Saudi Arabia and some arbovirus diseases in Iran and other countries in the world6–7. Moreover, P. papatasi is
Bioassay evaluation of residual activity of attractive toxic sugar-treated barrier fence in the control of Phlebotomus papatasi (Diptera: Psychodidae)
Abedin Saghafipour
1–2, Hassan Vatandoost
1, 3, Ali Reza Zahraei-Ramazani
2, Mohammad Reza Yaghoobi-Ershadi
2, Yavar Rassi
2, Mohammad Reza Shirzadi
4& Amir Ahmad Akhavan
2–31Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran; 2Department of Public Health, School of Public Health, Qom University of Medical Sciences, Qom; 3Department of Chemical Pollutants and Pesticides, Institute for Environmental Research, Tehran University of Medical Sciences, Tehran; 4Communicable Diseases Management Center, Ministry of Health and Medical Education, Tehran, Iran
ABSTRACT
Background & objectives: Phlebotomus papatasi is the main vector of the zoonotic cutaneous leishmaniasis (ZCL) in Qom Province and many other provinces of Iran. Attractive toxic sugar baits (ATSB) treated barrier fence is one of the new methods for controlling the vectors such as sandflies. The present study was designed to evaluate the residual activity of ATSB-treated barrier fence that was used in control of P. papatasi.
Methods: Following the selection of villages in Markazi district of Qom Province, central Iran during 2015 for ATSB and ASB (bait containing no active ingredient) methods; barrier fences on the ground in front of the rodent’s colony were installed. A total of four conical tubes were installed and fixed on surfaces of treated barrier net of dimension 25 × 25 cm at biweekly interval. In each conical tube, 10 sand flies were released and after 3 min of exposure they were transferred to sterile cups. After 24 h, the obtained results were recorded according to the survival and mortality rate of sandflies. These tests were carried out five days after the installation of barrier fences, and repeated every 15 days until the mortality rate decreased to 60–65%.
Results: The bioassay tests results showed that the mortality rate of P. papatasi on ATSB-treated barrier fence for 5, 15, 30 and 45 days after spraying was 100, 95.83, 88.18 and 66.67% respectively, which decreased to 50.83%
after 60 days.
Interpretation & conclusion: Persistence and residual activity of the active ingredient of the bait in the hot and dry climatic conditions of Qom Province remained significantly effective for at most 45 days, which subsequently decreased at a high rate. Hence, every 45 days barrier fences need to be impregnated with ATSB bait. The method also appeared cost-effective and could be practical in implementation of vector control programmes against ZCL.
Key words Attractive toxic sugar bait; bioassay test; Iran; Phlebotomus papatasi; Sandflies
the main vector of leishmaniasis in the Qom province of central Iran8. So far, various methods have been tested for the control of sandflies in different areas of the world such as: the use of pyrethroid insecticides in insecticide- treated bed nets and indoor residual spraying (IRS)9, the use of lace, curtains and bed nets soaked with insecti- cide10–11. Recently, a new promising strategy based on
“attract and kill” phenomenon/process for controlling vec- tors like sandflies, called attractive toxic sugar bait (ATSB) method12. In this method, vectors/sandflies are attracted to a surface or vegetation that coated/applied with ATSB containing oral toxins such as boric acid, which upon ingestion kills the insects12. It has been used in recent studies in three forms ATSB-treated barrier fence, spraying of ATSB on vegetation, and the intro- duction of ATSB on bait stations which have been suc- cessful against vectors such as Anopheles, Culex, Aedes and sandflies in different parts the world12–14. ATSB- treated barrier fence method has been exploited in the control of the populations of P. papatasi in Markazi dis- trict, a ZCL focus in Qom province, central Iran. In vari- ous investigations where insecticides have been used for vector control in the form of insecticide-treated bed nets, bioassay test has been used in the evaluation of residual activity of insecticides and the determination of next re- peated impregnation15–16. Interestingly, this study was designed to evaluate the residual activity of attractive toxic sugar treated barrier fence in the control of P.
papatasi by using bioassay test in Markazi district, Qom province in 2015.
MATERIAL & METHODS Study sites
This study was carried out in the rural regions (Koohsefid, Faraj Abad) of the Markazi district (latitude 34°09'–35°11'N and longitude 50°06'–51°58'E) in the Qom province of central Iran (elevation 1500 m above the sea level) from May to October 2015. This region is located near rodent burrows where P. papatasi (as the main vector) and Meriones libycus (as the reservoir) of ZCL have high abundance8. The soil profile consists mainly of clay and tamarix shrubs (T. aphylla) represent- ing the predominant vegetation in this region. Other plant species that grow in this district are Astragalus spp and Crataegus hawthorn. The climate is arid, with annual rainfall of 150 mm. The average maximum and mini- mum monthly relative humidity were 84 and 28% in De- cember and June, respectively. The average annual mini- mum and maximum temperature were –16.5 and 49°C in January and July, respectively.
Preparation of ATSB solutions
A solution of the bait was prepared as described by Beier et al14, with a little modification. The treatment sites consisted of 10% w/v brown sugar, 1% w/v boric acid and water (ATSB). A food dye, instead of boric acid, 10% w/v brown sugar and water (ASB) were used in the control site.
ATSB-treated barrier fence
In two villages of Koohsefid and Faraj Abad, rolls of semi rigid plastic net dimensioned 100 cm wide and suit- ably long enough depending on the extent of rodent colo- nies and 1 × 2 mm thick was used for building a bait barrier fence (Mesh size = 156 holes/inch2, 25 holes/cm2, denier = 75). Strips of cotton cloth 5 × 60 cm2 were con- nected transversally to the net, and their ends were folded around the margins and stapled. The strips were thus fixed to the net at intervals of 20 cm. After fixing the cloth strips, the net was rolled into a cylinder that was dipped into a bucket containing ATSB solution or solution with- out toxins. Initially, the number, location and extent of rodent colonies around the village were identified and characterized. Then, the nets of fences treated with ATSB and ASB were installed. This was done 500 m away from the distal houses of the outskirts of the village. In the experimental and control sites, barrier fences were in- stalled on the ground in front of the colony of rodents, using about 150 cm metal rods that were driven 50 cm deep into the ground at the suitable distances and another 100 cm on the ground as a barrier to prevent the movement of sandflies towards the village. Residual efficacy rates of ATSB-treated barrier were evaluated using the World Health Organization protocols of bioassay test17.
Sandflies collection
Sandflies for bioassay test were collected from in- door (bedroom, bathroom, toilets, hall and stables) fixed places in Mir Abad and Bagher Abad villages of Markazi district in Qom province from the first half of April 2015 to the first half of November 2015. To capture the sand flies, aspirators were used twice a month from sunset to sunrise 1 h before the bioassay test operation. The caught sandflies were transferred in holding tubes to the labora- tory in Qom Health Center. Following the bioassay test, sand flies were mounted in Puri’s medium18 and identi- fied after 24–72 h by considering the morphological char- acters19. Then, these were counted and segregated by sex.
The females were examined abdominally and the num- bers of unfed, fresh-blood fed and gravid (semi-gravid)
sandflies were recorded. The results of physiological situ- ation (parous and nulliparous) of sandflies were also re- corded as shown in Table 1.
Bioassay test
The ATSB-treated barrier fence nets (25 × 25 cm) were removed from the installed barrier in the villages and were fixed by fiberglass sheets with a dimension of 25 × 25 cm and four quarters of a circle with equal inter- vals on the nets for stabling the cones (Fig. 1). The diam- eter of each circle was 9 cm, separated by a distance of 3 cm from one another, while the distance from the circles to the edge was 2 cm. Both the fiberglass sheets were connected with scotch tape and immobilized from one side. In order to enhance and improve the test accuracy and pollution prevention frameworks to various chemi- cals, disposable plastic sheets were installed on the in- ternal surfaces with same dimensions, where the frame and the disposable plastic sheets were fixed to the inter- nal surfaces framework by using scotch tape. The ATSB- treated nets (25 × 25 cm) were removed and placed into the plastic sheets, cones placed on the quarters of the
circle of nets and the other fiberglass frame were fixed with clamps. Sandflies were immediately transferred to the laboratory, and after 1 h the sensitivity test was com- pleted. For the determination of the residual effect of ATSB bait on barrier fence, bioassay test (cone test) was used in the treatment village by conforming to the World Health Organization protocol, using conical chamber at biweekly interval17. In the case of reduced residual ef- fect of ATSB on barrier fences due to rainfall and so on, thesse were impregnated with ATSB solution again. In each conical tube, 10 sandflies were gently released in any cone at three replicates. Overall, in each biweekly interval, 120 sandflies were tested by using aspirator with a minimum exposure of 3 min on the treated surfaces.
Three replicates of untreated surfaces were used as nega- tive controls (ASB barrier fence nets) simultaneously.
After 3 min exposure, these sandflies were transferred into clean paper cups and kept in suitable conditions (25° ± 2°C and 80 ± 10% relative humidity) by placing a wet towel over the cups for 24 h. After the exposure time, both living and dead sandflies were transferred in netted cups to the laboratory, and the mortality was recorded after 24 h. If mortality rate of control tests was recorded between 5–20%, then the rates were corrected using Abbott’s formula. For the comparison of the residual ac- tivities in each sprayed surfaces, one-way ANOVA test was used. The criteria for the residual effect of tested insecticide were based on the mortality rates, and when this rate decreased to 60–65%17, the bioassays were stopped and the data were analyzed. To control the con- founding effect on the results of deaths at all stages of caught sandflies released in each cone, the sandflies were caught again gently and carefully by using an aspirator.
The obtained results were recorded according to the sur- vival and mortality rate of sand flies. These tests were carried out from 5 days after spraying and repeated ev- ery 15 days until the mortality rate decreased to 60–65%17. In addition, the barrier fences were reviewed and repaired every 15 days.
Fig. 1:Bioassay test (cone test) for evaluating residual efficacy rate of ATSB-treated barrier fence.
Table 1. Status of sandflies before exposed to ATSB, at bioassay tests on ATSB-treated barrier fence against Phlebotomus papatasi
Catch place Gender of sandflies Physiological status Age group
Male Female Gravid Semi- Blood- Unfed Nulli-parous Parous Total
gravid fed
Stables 283 234 34 37 64 99 79 155 517
Bedroom 9 7 1 2 2 2 0 7 16
Bathroom 15 7 1 3 0 3 1 6 22
Toilets 17 16 5 5 1 5 2 14 33
Halls 3 9 0 0 7 2 1 8 12
Total 327 273 41 47 74 111 83 190 600
this behavioral characteristic of the insect may be con- sidered to control the sandflies. ATSB has been success- fully used in vector control programs, especially in the control of sandflies which are leishmaniasis-transmitting vectors, in three applicable forms: (i) spraying of ATSB on vegetation; (ii) ATSB presented on bait stations; and (iii) ATSB-treated barrier fence12, 21. In some studies, ATSB consisted of 10% w/v brown sugar, boric acid 1%
w/v and water14. Boric acid (H3BO3), also called hydro- gen borate, is a weak, monobasic Lewis acid of boron often used as an antiseptic, insecticide, flame retardant, neutron absorber, or precursor of other chemical com- pounds. It exists in the form of colorless crystals or a white powder that dissolves in water22. Boric acid is a safe oral toxin, and an effective stomach poison for in- sects23. After introducing it to ATSB, sandflies ingest the toxic solutions and are killed. Boric acid may be much cheaper and locally made24.
One of the important endemic vector-borne diseases in Qom province is CL8. Based on epidemiological and molecular studies, the type of CL prevalent in the dis- tricts of the Qom province is ZCL8. The two endemic foci of ZCL are Kahak and Markazi district8. Previous studies have revealed that, in these ZCL foci, usually Leishmania-infected sandflies move from rodents bur- row towards human dwellings in order to continue biting and feeding on human sources25.
In the present study, ATSB-treated barrier fence was used in the study villages located in close proximity to the frontal view of rodent borrows facing toward human dwellings. The P. papatasi species is the main sandfly vector of ZCL in Iran26. The residual efficacy would help in the determination of next repeated impregnation. In many previous studies insecticides have been applied for phlebotomine sandflies control such as insecticide-treated bed nets, bioassay test has been used and tested15–16. Based on the bioassay test, ATSB-treated barrier fence
Table 3. Results of bioassay tests on ASB-treated barrier fence against Phlebotomus papatasi in Markazi district, Qom province 2015
Days after No. of No. of Mortality rate ±
application sandflies exposed sandflies died S.E. of sandflies to ATSB-treated after exposure exposed to ATSB
barrier fence to ATSB
5 120 8 6.67 ± 2.28
15 120 6 5.00 ± 4.24
30 120 10 8.34 ± 8.75
Monthly mean 120 8 6.67
45 120 8 6.67 ± 10.35
60 120 14 11.67 ± 7.84
Monthly mean 120 11 8.92
RESULTS
The bioassay test results showed that the mortality rate of sandflies exposed to ATSB-treated barrier fence on Days 5, 15, 30 and 45 after spraying was 100, 95.83, 88.18 and 66.67%, respectively (Table 2). Subsequent persistence and residue effect of this method decreased, as the mortality rate after 60 days decreased to 50.83%.
Table 2. Results of bioassay tests on ATSB-treated barrier fence against Phlebotomus papatasi in Markazi district,
Qom province 2015
Days after No. of No. of Mortality rate ±
application sandflies exposed sandflies died S.E. of sandflies to ATSB-treated after exposure exposed to ATSB
barrier fence to ATSB
5 120 120 100
15 120 115 95.83 ± 4.35
30 120 106 88.18 ± 6.24
Monthly mean 120 113.67 91
45 120 81 66.67 ± 7.4
60 120 61 50.83 ± 65
Monthly mean 120 71 58.75
Fig. 2:The month-wise density of Phlebotomus papatasi in Markazi district, Qom province, 2015.
But the mortality rate of exposed sandflies to ASB-treated barrier fence after 5, 15, 30, 45 and 60 days were 6.67, 5, 8.34, 6.67 and 11.67%, respectively (Table 3). The activity of P. papatasi in the region started from May and ended in November, with two peaks observed in early June and late July (Fig. 2).
DISCUSSION
This is the first formal report on the field evaluation of ATSB-treated barrier fence active ingredient in Qom province, central Iran. The control method employed in this study is quite considerable, as both male and female phlebotomine sandflies, like other biting flies, require sugar nectar from plants and shrubs for survival20. Hence,
in Qom province climate (arid climate) was found effec- tive for 45 days at most. Therefore, every 45 days barrier fences need to be impregnated with ATSB bait. The mor- tality rate of sandflies exposed to ATSB treated barrier fence on Days 5, 15, 30, 45 and 60 was 100, 95.83, 88.18, 66.67 and 50.83%, respectively. But the mortality rate of exposed sandflies to ASB-treated barrier fence after 5, 15, 30, 45 and 60 days was 6.67, 5, 8.34, 6.67 and 11.67%, respectively. This value of the mortality rate was both normal and expected. Possibly, the mortality rate among sandflies which was exposed to ASB may be attributed to the relocation and transportation of sandflies. Because P. papatasi activity started from May and ended in No- vember in the study region, and residents received most infected bites during July to September, a majority of patients come to clinics for treatment from October until late December27. ATSB method correlates well with other sandfly control methods that create a barrier between humans and sandflies such as insecticide-treated bednets (ITNs) or indoor residual spraying (IRS). Also residual efficacy of 45 days can be cost-effective and affordable in comparison is to control methods. Although the re- sidual effect of ITNs may be >45 days as reported in some studies, bednets are exposed to washing and sun- shine and might lose their residual effect quickly28–29. In addition, ITNs bednets or IRS are not user-friendly most of the time. Eventually, ATSB method is done in desert areas away from human dwellings, and remains accept- able and convenient for inhabitants.
CONCLUSION
The results indicated that persistence and residual ac- tivity of the active ingredient of the bait in the climatic conditions of Qom province is effective for at most 45 days, which subsequently decrease at a higher rate. Hence, every 45 days barrier fences need to be impregnated with ATSB bait. So, in ZCL foci, ATSB can be one of the integrated CL vector control program. Based on the re- sults of study, this method is cost-effective and it can work as a new tool for vector control that can be integrated with other control methods in integrated vector manage- ment (IVM) in ZCL foci such as in Qom province.
Conflict of interest
The authors declare no conflict of interest.
ACKNOWLEDGEMENTS
The study was funded by the Tehran University of Medial Sciences, Iran through project No. 29826. The
authors thank health workers in Qom Health Center for helping in the field work.
REFERENCES
1. Maroli M, Feliciangeli MD, Bichaud L, Charrel RN, Gradoni L.
Phlebotomine sandflies and the spreading of leishmaniases and other diseases of public health concern. Med Vet Entomol 2013;
27(2): 123–47.
2. Zahraei-Ramazani A, Wannigama DL. Phlebotominae sandflies- morphological and molecular approaches. Germany: Laplam-bert Publishing 2016; p.1–3.
3. Alkan C, Bichaud L, de Lamballerie X, Alten B, Gould EA, Charrel RN. Sandfly-borne phleboviruses of Eurasia and Africa:
Epidemiology, genetic diversity, geographic range, control mea- sures. Antiviral Res 2013; 100(1): 54–74.
4. Vieira VP, Ferreira AL, Biral dos Santos C, Leite GR, Ferreira GE, Falqueto A. Peridomiciliary breeding sites of phlebotomine sandflies (Diptera: Psychodidae) in an endemic area of Ameri- can cutaneous leishmaniasis in southeastern Brazil. Am J Trop Med Hyg 2012; 87(6): 1089–93.
5. Killick-Kendrick R. The biology and control of phlebotomine sand flies. Clin Dermatol 1999; 17(3): 279–89.
6. Killick-Kendrick R, Leaney AJ, Peters W, Rioux JA, Bray RS.
Zoonotic cutaneous leishmaniasis in Saudi Arabia the incrimi- nation of Phlebotomus papatasi as the vector in the Al-Hassa oasis. Trans R Soc Trop Med Hyg 1985; 79(2): 252–5.
7. Tesh R, Saidi S, Javadian E, Loh P, Nadim A. Isfahan virus, a new vesiculovirus infecting humans, gerbils, and sandflies in Iran.
Am J Trop Med Hyg 1977; 26(2): 299–306.
8. Rassi Y, Saghafipour A, Abai MR, Oshaghi MA, Rafizadeh S, Mohebai M, et al. Phlebotomus papatasi and Meriones libycus as the vector and reservoir host of cutaneous leishmaniasis in Qomrood district, Qom province, central Iran. Asian Pac J Trop Med 2011; 4(2): 97–100.
9. Maroli M, Khoury C. Current approaches to the prevention and control of leishmaniasis vectors.Vet Res Commun 2006; 30: 49–
52.
10. Kroeger A, Avila EV, Morison L. Insecticide-impregnated cur- tains to control domestic transmission of cutaneous leishmania- sis in Venezuela: Cluster randomized trial. Brit Med J 2002; 325:
810–13.
11. Courtenay O, Gillingwater K, Gomes PA, Garcez LM, Davies CR. Deltamethrin-impregnated bednets reduce human landing rates of sandfly vector Lutzomyia longipalpis in Amazon house- holds. Med Vet Entomol 2007; 21(2): 168–76.
12. Müller GC, Schlein Y. Different methods of using attractive toxic sugar baits (ATSB) for the control of Phlebotomus papatasi. J Vector Ecol 2011; 36 (Suppl 1): S64–70.
13. Xue RD, Kline DL, Ali A, Barnard DR. Application of boric acid baits to plant foliage for adult mosquito control. J Am Mosq Control Assoc 2006; 22(3): 497–500.
14. Beier JC, Müller GC, Weidong Gu, Arheart KL, Schlein Y. At- tractive toxic sugar bait (ATSB) methods decimate populations of Anopheles malaria vectors in arid environments regardless of the local availability of favoured sugar-source blossoms. Malar J 2012; 11: 31.
15. Denlinger DS, Lozano-Fuentes S, Lawyer PG, Black WC IV, Bernhardt SA. Assessing insecticide susceptibility of laboratory Lutzomyia longipalpis and Phlebotomus papatasi sandflies (Diptera: Psychodidae: Phlebotominae). J Med Entomol 2015;
52(5): 1003–12.
16. Bongiorno G, Panchetti F, Zaim M, Maroli M. Laboratory study to investigate the efficacy of cyfluthrin EW-treated nets against phlebotomine sandflies. Ann Ist Super Sanità 2005; 41(2): 247–
52.
17. Guideline for testing mosquito adulticides for indoor residual spraying and treatment of mosquito nets. Geneva: World Health Organization 2006. WHO/CDS/NTD/WHOPES/GCDPP/2006.3;
p. 1–60.
18. Smart J, Jordan K, Whittick RJ. Insects of medical importance.
IV edn. British Museum of Natural History. Oxford: Alden Press 1965; p. 286–8.
19. Theodor O, Mesghali A. On the phlebotominae of Iran. J Med Entomol 1964; 1: 285–300.
20. Müller GC, Schlein Y. Nectar and honey dew feeding of Phle- botomus papatasi in a focus of Leishmania major in Neot Hakikar oasis. J Vector Ecol 2004; 29(1): 154–8.
21. Schlein Y, Müller GC. Experimental control of Phlebotomus papatasi by spraying attractive toxic sugar bait (ATSB) on vegetation. Trans R Soc Trop Med Hyg 2010; 104(12): 766–71.
22. Allen AH, Tankard AR. The determination of boric acid in ci- der, fruits, etc. Analyst 1904; 29: 301–4.
23. Habes D, Kilani-Morakchi S, Aribi N, Farine JP, Soltani N. Bo- ric acid toxicity to the German cockroach, Blattella germanica:
Alterations in midgut structure, and acethylcholinesterase and gluthatione S-transferase activity. Pest Biochem Physiol 2006;
84(1): 17–24.
24. Müller GC, Junnila A, Schlein Y. Effective control of adult Culex pipiens by spraying an attractive toxic sugar bait solution in the vegetation near larval habitats. J Med Entomol 2010; 47(1):
63–6.
25. Mascari TM, Foil LD. Oral treatment of rodents with ivermectin for the control of Phlebotomus papatasi (Diptera: Psychodidae) under laboratory conditions. Vet Parasitol 2010; 171(1–2): 130–
5.
26. Yaghoobi-Ershadi MR. Phlebotomine sandflies (Diptera: Psy- chodidae) in Iran and their role on Leishmania transmission. J Arthropod-Borne Dis 2012; 6(1): 1–17.
27. Saghafipour A, Rassi Y, Abai MR. Fauna and monthly activity of sandflies at cutaneous leishmaniaisis focus in Ghanavat district, Qom province. J Ilam Univ Med Sci 2013;
21(3): 64–71.
28. Raeisi A, Abai MR, Akbarzadeh K, Nateghpour M, Sartipi M, Hassanzehi A, et al. Residual effects of deltamethrin WG 25%
as a new formulation on different surfaces against Anopheles stephensi in southeastern Iran. J Arthropod-Borne Dis 2010; 4(1):
60–5.
29. Vatandoost H, Abai MR, Abbasi M, Shaeghi M, Abtahi M, Rafie F. Designing of a laboratory model for evaluation of the residual effects of deltamethrin (K-othrine WP 5%) on different surfaces against malaria vector, Anopheles stephensi (Diptera: Culicidae).
J Vector Borne Dis 2009; 46(4): 261–7.
Correspondence to: Prof. Hassan Vatandoost, Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
E-mail: [email protected]; [email protected] Received: 9 May 2016 Accepted in revised form: 26 September 2016