Background & objectives: Phlebotomus argentipes is the vector for visceral leishmaniasis in India. Thedevelopment of resistance in kala-azar vector to DDT has been reported from various parts of India. The mainobjective of this study was to generate information on insecticides susceptibility status of P. argentipes to DDT,malathion and deltamethrin in different parts in three states of India.Methods: Phlebotomus argentipes were collected from different villages, identified and used to investigate thesusceptibility status against DDT, malathion and deltamethrin as per the WHO standard methods.Results: Phlebotomus argentipes was resistant to DDT in different areas, viz. PHCs Murumgaon in Maharashtra;Ramgarh in Jharkhand; Kodah, Falka, Mahua and Lalganj in Bihar. In Phulwari Shareef PHC of Patna districtin Bihar, DDT produced 89% mortality in P. argentipes, indicating resistant/tolerance (verification required) toDDT. The corrected percent mortality to malathion (5%) in different areas ranged between 98 and 100%; and todeltamethrin (0.05%) between 98.4 and 100%. The results showed that the tested P. argentipes are susceptibleto malathion and deltamethrin.Conclusion: Phlebotomus argentipes are still susceptible to malathion and deltamethrin, but resistant to DDT.The susceptibility status of P. argentipes should be monitored regularly in diversified situations to ascertain thejudicious use of insecticides being used for indoor residual spraying in the programme for rational use ofappropriate insecticide

R.K. Singh, P.K. Mittal & R.C. Dhiman

Directory of Open Access Journals

J Vector Borne Dis 49, December 2012, pp. 254–257Insecticide susceptibility status of Phlebotomus argentipes, a vector ofvisceral leishmaniasis in different foci in three states of IndiaR.K. Singh, P.K. Mittal & R.C. DhimanNational Institute of Malaria Research (ICMR), New Delhi, IndiaABSTRACTBackground & objectives: Phlebotomus argentipes is the vector for visceral leishmaniasis in India. Thedevelopment of resistance in kala-azar vector to DDT has been reported from various parts of India. The mainobjective of this study was to generate information on insecticides susceptibility status of P. argentipes to DDT,malathion and deltamethrin in different parts in three states of India.Methods: Phlebotomus argentipes were collected from different villages, identified and used to investigate thesusceptibility status against DDT, malathion and deltamethrin as per the WHO standard methods.Results: Phlebotomus argentipes was resistant to DDT in different areas, viz. PHCs Murumgaon in Maharashtra;Ramgarh in Jharkhand; Kodah, Falka, Mahua and Lalganj in Bihar. In Phulwari Shareef PHC of Patna districtin Bihar, DDT produced 89% mortality in P. argentipes, indicating resistant/tolerance (verification required) toDDT. The corrected percent mortality to malathion (5%) in different areas ranged between 98 and 100%; and todeltamethrin (0.05%) between 98.4 and 100%. The results showed that the tested P. argentipes are susceptibleto malathion and deltamethrin.Conclusion: Phlebotomus argentipes are still susceptible to malathion and deltamethrin, but resistant to DDT.The susceptibility status of P. argentipes should be monitored regularly in diversified situations to ascertain thejudicious use of insecticides being used for indoor residual spraying in the programme for rational use ofappropriate insecticide.Key words Kala-azar; Phlebotomus argentipes; resistance; susceptibilityINTRODUCTIONVisceral leishmaniasis (VL) also known as kala-azar,Black fever, and Dumdum fever, first came to the atten-tion in the year 1824 in Jessore, India (now Bangladesh),where it was initially thought to be a form of malaria.Leishmaniasis is a disease caused by protozoan parasitesof the Genus-Leishmania. The agent of the disease wasalso first isolated from endemic area of West Bengal inIndia by Scottish Doctor William Leishman and Irish Phy-sician Charles Donovan. The species was named after bothof them Leishmania donovani. Today, the name kala-azaris commonly used along with the scientific name visceralleishmaniasis for the severe form of the disease causedby L. donovani1.In southeast Asia, approximately 200 million peopleare at the risk of VL and five lakh new cases are regis-tered annually2. VL is a serious public health problem inIndia since 1970s, in the state of Bihar and latter spreadto West Bengal and eastern Uttar Pradesh. In 1977, asample survey estimated the number of cases to be aboutone lakh with 4500 deaths in Bihar3. The vector of leish-maniasis world over belongs to order Diptera of classInsecta (Phylum- Arthopoda). Fauna of Indian sub-zoneis represented by phlebomine and sergentomyia species4.In India, VL caused by L. donovani is transmitted by Phle-botomus argentipes5, 6. About 165.4 million populationand 12 states are suffering from kala-azar, of which 48districts in four states, namely West Bengal, Bihar, Uttar-Pradesh and Jharkhand are endemic7. In the year 2010,28,941 cases of kala-azar and 105 deaths were reported.The control strategy is based on the use of insecticidesfor reducing populations of kala-azar vector. In Bihar,two rounds of DDT spraying in a year have been con-ducted in kala-azar endemic districts since 1953, firstround of indoor residual spraying (IRS) with DDT inFebruary–March and second round in May–June3,8,9.These measures are now failing to control kala-azar inWest Bengal, Bihar, Uttar Pradesh and Jharkhand states.The reason may be due resistance in P. argentipes to DDTused in the national vector control programme in India.A recent review on P. argentipes susceptibility to differ-ent insecticides in the Indian subcontinent since 1978showed that DDT resistance has been reported in India 255Singh et al: Susceptibility of P. argentipes to insecticides in Indian statessince early 1990’s but the results were variable. Thoughsome workers have reported development of resistancein kala-azar vector to DDT from various parts ofIndia3,10–20, the present study was initiated to generatemore information on insecticide susceptibility status ofP. argentipes to DDT, malathion, and deltamethrin inkala-azar endemic villages of five primary health centres(PHCs)/districts of different states, viz. Vaishali, Katiharand Patna (Bihar), Dumka (Jharkhand) and Gadchiroli(Maharashtra).MATERIAL & METHODSInsecticide susceptibility tests were carried out in themonths of February–March 2008 in Vaishali, Patna;March–April 2008 in Katihar (Bihar); March–April 2009in Dumka district (Jharkhand) and January–March 2010in Gadchiroli (Maharashtra) as per the World Health Or-ganization (WHO) procedure against various insecti-cides21–22. Sandflies were collected from unsprayed hu-man dwellings and mixed dwellings of different villagesand PHCs of different states in the early morning (0500to 0700 hrs) with the help of suction tube and were pro-vided 10% glucose solution soaked in cotton pads.Sandflies collected from the fields were transported inBarraud cages covered by wet cloth to the field laborato-ries at the PHC level for identification of P. argentipeswhich can easily be distinguished from P. Papatasi basedon blackish body colour and silvery legs in P. argentipes.From a pool of collection five sandflies were killed andidentified through proboscis and genitalia using identifi-cation key4 for confirmation. After confirming P.argentipes the remaining population was used for sus-ceptibility test. Insecticide impregnated and control pa-pers for respective insecticides received from WHO Col-laborating Centre at the University of Malaysia, withdifferent diagnostic dosages were used for detection ofresistance to DDT (4%), malathion (5%) and deltamethrin(0.05%).Full-fed P. argentipes were exposed to WHOinsecticide papers impregnated with diagnostic doses ofinsecticides, i.e. DDT (4%), malathion (5%) anddeltamethrin (0.05%) as per the standard WHO methodfor one hour22. Temperature and humidity were controlledat 26 ± 2°C and 70–80% RH respectively. Four to fivereplicates containing 25 female sandflies were used si-multaneously for each insecticide. Two replicates of 20–25 sandflies for control were also held parallel to eachtest. After exposure to the requisite period, the holdingtubes were kept for recovery in dark and cool places im-mediately. Cotton pads soaked in 10% glucose solutionwere given as supplementary food during the recoveryperiod for 24 h. The percent mortalities were calculatedby scoring the dead and alive sandflies after 24 h of re-covery period and mortality in sandflies was correctedby using Abbott’s formula23, in case the control mortal-ity was within 5–20% that was expressed as correctedpercent mortality.RESULTS & DISCUSSIONResults of susceptibility tests on P. argentipes againstDDT (4%), malathion (5%) and deltamethrin (0.05%) aregiven in Table 1. The corrected percent mortality of adultP. argentipes to DDT (4%) ranged between 31 and 89%in different areas, which indicate resistance/tolerance toDDT. Though the species was resistant to DDT in differ-ent areas in PHCs Murumgaon, Ramgarh, Kodah, Falka,Mahua and Lalganj, in Phulwari Shareef PHC of Patnadistrict in Bihar, DDT produced 89% mortality in P.argentipes, indicating tolerance (verification required) toDDT. The corrected percent mortality to malathion (5%)ranged between 98 and 100%; and to deltamethrin (0.05%)between 98.4 and 100%. The results were almost same indifferent areas indicating that the tested P. argentipes arestill susceptible to malathion and deltamethrin. InMurumgaon PHC of Gadchiroli district in Maharashtra,DDT resistance was very high as compared to other areasstudied, showing only 31% mortality in sandflies againstDDT.DDT is still being used in the kala-azar controlprogramme in Bihar and other endemic states. Most ofearlier research workers have reported development oftolerance/resistance in sandflies against DDT from vari-ous parts of India3,10–19. Development of resistance toDDT in P. argentipes has been reported from Samastipur,Bakhtiyarpur, Dharbhanga and Vaishali districts of Bihar.However, P. argentipes has been reported to be suscep-tible to DDT in Samastipur and Patna districts13,18. Thereare only a few reports showing susceptibility status ofsandflies to malathion and deltamethrin. Most of thesereports have shown P. argentipes to be fully susceptibleto malathion and deltamethrin in India18. However,sandflies have shown to be resistant to malathion andalso deltamethrin from Puducherry, a non-endemic areafor kala-azar20. Our study has shown resistance in P.argentipes to DDT only, while these are still susceptibleto malathion and deltamethrin. Resistance to DDT in P.argentipes may be due to prolonged use of DDT for in-door residual spray since 1976 in vector control activitiestargeting kala-azar.Our study reveals an increasing resistance trend in J Vector Borne Dis 49, December 2012256P. argentipes to DDT but still susceptible to deltamethrinand malathion. Similar results showing 100% suscepti-bility of P. argentipes to deltamethrin and malathion havebeen reported by other authors from different areas18. Thecurrent failure to control the transmission of L. donovaniin these districts of Bihar relying on IRS with DDT canbe partially explained by the resistance to this compoundand thus other insecticides should be evaluated to replaceit. District-wise susceptibility status of sandflies to theinsecticides being used in the programme should be moni-tored for judicious use of effective insecticides for kala-azar control. However, the first requirement for a suc-cessful vector control programme remains the quality ofIRS implementation24. There is also a need to educatecommunity for enhanced spray coverage of >85% ofhouses and rooms at least. There is a need to strictly moni-tor whether two rounds of IRS activities are done duringcoverage of houses.High endemicity of kala-azar in Bihar and Jharkhandarea, which is receiving two rounds of IRS with DDT,warrants that synthetic pyrethroids use should be under-taken especially in Bihar and Jharkhand states as pernorms of the National Vector Borne Disease ControlProgramme. Given the constraints of using IRS activityfor control of VL, alternative tools such as insecticidalbed nets (ITNs)/ long-lasting insecticidal nets (LLINs)may also be used. Although untreated nets may providesome degree of personnel protection against sandfly bites,but insecticide treated net25, particularly long-lasting in-secticidal nets can provide better protection againstsandfly as well as control of VL26. There are, however,conflicting reports about the role of LLINs in control ofvisceral leishmaniasis vectors25–28. Dinesh et al25 showedthat LLINs although reduced the density of P. argentipesmales but not of females, as LLINs failed to reduce theentry rate of females in selected households27. However,another study by Picado et al26 reported that LLINs sig-nificantly reduced the density of P. argentipes in a vil-lage-scale trial and suggested that LLINs can be success-fully deployed as part of the VL control programme28.Recently, a trial with deltamethrin-impregnated LLINsagainst P. argentipes has shown successful control of kala-azar in the study areas in Bihar state (unpublished per-sonnel communication) suggesting that large-scale inter-vention may be undertaken with LLINs in areas with DDTresistant kala-azar vectors.ACKNOWLEDGEMENTSThe laboratory and field assistance given by the staff ofNIMR, Messrs V.P. Singh, Surender Kumar and H.K.Jha is gratefully acknowledged. Authors are also thank-ful to the DMOs of Vaishali, Katihar, Dumka, Gadchirolidistricts and their staff for providing the information onkala-azar incidence and use of insecticide in IRS in vec-tor control. This paper bears the NIMR publication screen-ing committee approval No. 008/2012.Table 1. Susceptibility of P. argentipes to insecticides in different states of IndiaName of state/ Insecticide Sandflies exposed Sandflies dead %  Mortality in Corrected Statusdistrict/PHC  (% conc. tested)   sandflies  mortality inTest Control Test Control Test Control  (%)Maharashtra/ DDT (4) 100 (4) 25 (1) 31 0 31 0 31 RGadchiroli/ Malathion (5) 100 (4) 25 (1) 98 0 98 0 98 SMurumgaon Deltamethrin (0.05) 100 (4) 25 (1) 100 1 100 4 100 SJharkhand/ DDT (4) 100 (4) 45 (2) 69 0 69 0  69 RDumka/Ramgarh Malathion (5) 100 (4) 45 (2) 100 0 100 0 100 SDeltamethrin (0.05) 100 (4) 45 (2) 100 1 100 2.2 100 SBihar/Katihar/ DDT (4) 125 (5) 40 (2) 83 0 66.4 0 66.4 RKodah, Falka Malathion (5) 125 (5) 40 (2) 125 1 100 2.5 100 SDeltamethrin (0.05) 125 (5) 40 (2) 123 0 98.4 0 98.4 SBihar/Vaishali/ DDT (4) 100 (4) 25 (1) 61 0 61 0 61 RMahua, Lalganj Malathion (5) 100 (4) 25 (1) 100 0 100 0 100 SDeltamethrin (0.05) 100 (4) 25 (1) 100 1 100 0 100 SBihar/Patna/ DDT (4) 100 (4) 25 (1) 89 0 89 4 89 VRPhulwari Shareef Malathion (5) 100 (4) 25 (1) 100 0 100 0 100 SDeltamethrin (0.05) 100 (4) 25 (1) 100 1 100 4 100 SFigures in parentheses indicate the number of replicates; S–Susceptible (mortality ≥98%); R–Resistant (mortality ≤80%); VR–Verificationrequired; Tolerant (81–97%). 257Singh et al: Susceptibility of P. argentipes to insecticides in Indian statesREFERENCES1. Available from: http://en.wikipedia.org/wiki/visceral_leishmaniasis (Accessed on October 16, 2012).2. Desjeux P. Leishmaniasis: Current situation and new perspec-tives. Comp Immuno Microb Infect Dis 2004; 27: 305–18.3. Kishore K, Kumar V, Kesari S, Dinesh DS, Kumar AJ, Das P,Bhattacharya SK. Vector control in leishmaniasis. Indian J MedRes 2006; 123: 467–72.4. Kalra NL, Bang YH. Manual on entomology in visceral leish-maniasis. New Delhi: World Health Organization 1988. Docu-ment SEA/VBC/35.5. Swaminath CS, Shortt HE, Anderson LAP. Transmission of In-dian kala-azar to man by the bites of Phlebotomus argentipes.Indian J Med Res 1942; 30: 473–7.6. Singh SP, Picado A, Boelaert M, Gidwani K, Andersen EW. Theepidemiology of Leishmania donovani infection in high trans-mission foci in India. Trop Med Int Health 2010; 2(15 Suppl):12–20.7. Available from: http://nvbdcp.nic.in/ (Accessed on  May 9, 2011).8. Chemical methods for the control of arthropod vectors and pestsof public health importance. Geneva: World Health Organiza-tion 1984; p. 43.9. Kumar V, Kesari S, Dinesh DS, Tiwari AK, Kumar AJ, KumarR, et al. A report on the indoor residual spraying (IRS) in thecontrol of Phlebotomus argentipes, the vector of visceral leish-maniasis in Bihar (India): An initiative towards total eliminationtargeting 2015 (Series-1). J Vector Borne Dis 2009; 46: 225–9.10. Kaul SM, Bhatnagar VN, Mathur KK, Wattal BL. Preliminaryobservations on the susceptibility status P. argentipes and P.papatasi to DDT in two districts of North Bihar. J Commun Dis1978; 10: 208.11. Joshi GC, Kaul SM, Wattal BL. Susceptibility of sand flies toorganochlorine insecticides in Bihar. J Commun Dis 1979; 11:209.12. Rahman SJ, Wattal BL, Mathur KK, Joshi GC, Kumar K. Sus-ceptibility of laboratory strain of P. papatasi to organochlorineinsecticides. J Commun Dis 1982; 14: 122–4.13. Mukhopadhyay AK, Saxena NB, Narasimham MV. Susceptibil-ity of Phlebotomus argentipes to DDT in some kala-azar en-demic area of Bihar (India). Indian J Med Res 1990; 91: 458–60.14. Joshi RD, Rai RN. Impact of DDT spraying on populations of P.argentipes and P. papatasi in Varanasi district of Uttar Pradesh.J Commun Dis 1994; 26: 56–8.15. Basak B, Tandan N. Observations on susceptibility status of P.argentipes to DDT in district south 24 Parganas, West Bengal. JCommun Dis 1995; 27: 196–7.16. Dhiman RC, Mittal PK. A note on susceptibility of P. papatasi(Scopoli) populations to insecticides. J Commun Dis 2000; 32(1):65–6.17. Singh R, Das RK, Sharma SK. Resistance of sand flies to DDTin kala-azar endemic districts of Bihar, India. Bull WHO 2001;79: 793.18. Dhiman RC, Raghavendra K, Kumar V, Kesari S, Kishore K.Susceptibility status of Phlebotomus argentipes to insecticidesin Districts Vaishali and Patna (Bihar). J Commun Dis 2003;35(1): 49–51.19. Kishore K, Kumar V, Kesari S, Bhattacharya SK, Das P. Sus-ceptibility of Phlebotomus argentipes against DDT in endemicdistricts of North Bihar, India. J Commun Dis 2004; 36: 41–4.20. Amalraj DD, Sivagnaname N, Srinivasan R. Susceptibility ofPhlebotomus argentipes and P. papatasi (Diptera: Psychodidae)to insecticides. J Commun Dis 1999; 31: 177–80.21. Manual on practical entomology in malaria. Pt. II: Methods andtechniques. Geneva: World Health Organization 1975; p. 191.22. Instructions for determining the susceptibility or resistance ofadult black flies, sand flies and biting midges to insecticides.Geneva: World Health Organization 1981; WHO/VBC/81.810,p. 1–6.23. Abbott WS. A method of computing the effectiveness of an in-secticide. J Econ Entomol 1925; 18: 265–7.24. Mondal D, Singh SP, Kumar N, Joshi A, Sundar S. Visceral leish-maniasis elimination programme in India, Bangladesh, and Nepal:Reshaping the case finding/case management strategy. PLoS NeglTrop Dis 2009; 3: 355.25. Dinesh DS, Das P, Picado A, Davies C, Speybroeck N, Ostyn B,Boelaert M, Coosemans M. Long-lasting insecticidal nets fail athousehold level to reduce abundance of sandfly vector Phleboto-mus argentipes in treated houses in Bihar (India). Trop Med IntHealth 2008; 13(7): 953–8.26. Picado A, Kumar V, Das M, Burniston I, Roy L, Suman R, DineshD, Coosemans M, Sundar S, Shreekant K, Boelaert M, DaviesC, Cameron M. Effect of untreated bed nets on blood-fed Phle-botomus argentipes in kala-azar endemic foci in Nepal and In-dia. Mem Inst Oswaldo Cruz 2009; 104(8): 1183–6.27. Ostyn B, Vanlerberghe V, Picado A, Dinesh DS, Sundar S,Chappuis F, Rijal S, Dujardin JC, Coosemans M, Boelaert M,Davies C. Vector control by insecticide-treated nets in the fightagainst visceral leishmaniasis in the Indian subcontinent, what isthe evidence?. Trop Med Int Health 2008; 13(8): 1073–85.28. Picado A, Das ML, Kumar V, Kesari S, Dinesh DS, Roy L, RijalS, Das P, Rowland M, Sundar S, Coosemans M, Boelaert M,Davies CR. Effect of village-wide use of long-lasting insecti-cidal nets on visceral Leishmaniasis vectors in India and Nepal:A cluster randomized trial. PLoS Negl Trop Dis 2010; 4(1): e587.Correspondence to: Dr R.K. Singh, Research Scientist, National Institute of Malaria Research, Sector 8, Dwarka, New Delhi–110 077, India.E-mail: singhriku@yahoo.co.inReceived: 21 June 2012 Accepted in revised form: 22 October 2012

Journal of Vector Borne Diseases

Insecticide susceptibility status of Phlebotomus argentipes, a vector of visceral leishmaniasis in different foci in three states of India

http://doaj.org/search?source=%7B%22query%22%3A%7B%22bool%22%3A%7B%22must%22%3A%5B%7B%22term%22%3A%7B%22id%22%3A%22022e4391de8741e2b18b1364d8519f1a%22%7D%7D%5D%7D%7D%7D

Insecticide susceptibility status of Phlebotomus argentipes, a vector of visceral leishmaniasis in different foci in three states of India

Abstract

Similar works

Full text

Available Versions

Directory of Open Access Journals