An outbreak investigation of visceral leishmaniasis among residents of Dharan town, eastern Nepal, evidence for urban transmission of Leishmania donovani

BMC Infectious Diseases

Marleen Boelaert¹  Suman Rijal²  Narayan Raj Bhattarai²  Murari Lal Das²  Filip Meheus¹  Lalita Roy²  Epco Hasker¹  Surendra Uranw¹ 

[1]Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium

[2]B.P. Koirala Institute of Health Sciences, Ghopa, 56700, Dharan, Nepal

关键词: Nepal;    Sand fly infection;    Disease transmission;    Outbreak;    Risk factor;    Visceral leishmaniasis;    Kala-azar;   

Others  :  1158572
DOI  :  10.1186/1471-2334-13-21

 received in 2012-06-15, accepted in 2013-01-14,  发布年份 2013

【 摘 要 】

Background

Visceral leishmaniasis (VL) is a predominantly rural disease, common in the low lands of eastern Nepal. Since 1997 VL cases have also been reported among residents of the city of Dharan. Our main research objective was to find out whether there had been local transmission of VL inside the city.

Methods

We conducted an outbreak investigation including a case–control study; cases were all urban residents treated for VL between 2000 and 2008 at BP Koirala Institute of Health Sciences, a university hospital in the city. For each case, we selected four random controls, with no history of previous VL; frequency-matched for age. Cases and controls were subjected to a structured interview on the main exposures of interest and potential confounders; a binominal multilevel model was used to analyze the data. We also collected entomological data from all neighborhoods of the city.

Results

We enrolled 115 VL patients and 448 controls. Cases were strongly clustered, 70% residing in 3 out of 19 neighborhoods. We found a strong association with socio-economic status, the poorest being most at risk. Housing was a risk factor independent from socio-economic status, most at risk were those living in thatched houses without windows. ‘Sleeping upstairs’ and ‘sleeping on a bed’ were strongly protective, OR of 0.08 and 0.25 respectively; proximity to a case was a strong risk factor (OR 3.79). Sand flies were captured in all neighborhoods; in collections from several neighborhoods presence of L. donovani could be demonstrated by PCR.

Conclusion

The evidence found in this study is consistent with transmission of anthroponotic VL within the city. The vector P. argentipes and the parasite L. donovani have both been identified inside the town. These findings are highly relevant for policy makers; in VL endemic areas appropriate surveillance and disease control measures must be adopted not only in rural areas but in urban areas as well.

【 授权许可】

   
2013 Uranw et al.; licensee BioMed Central Ltd.

【 图 表 】

Figure 1.

Figure 2.

【 参考文献 】

• [1]World Health Organisation: Control of the leishmaniasis. World Health Organ Tech Rep Ser 2010, 949:186.
• [2]World Health Organisation/TDR: Press release for the Elimination of Kala-azar from endemic countries in the South-East Asia region. Health Ministers Sign Memorandum of Understanding. Geneva/New Delhi: WHO; 2005. [document on the internet]. Available from: http://www.who.int/tdrold/publications/tdrnews/news75/leish_elimination.htm webcite. (accessed on 17 May 2011)
• [3]Bista MB: National overview of Kala-azar in Nepal. In Kala-azar in Nepal: principals, practices and public health perspectives. Edited by Bastola S, Karki P, Rijal S, Gautam A. Kathmandu, Nepal: EDCD/BPKIHS/WHO; 1998:1-5.
• [4]Bern C, Joshi AB, Jha SN, Das ML, Hightower AW, Thakur GD, Bista MB: Factors associated with visceral leishmaniasis in Nepal: bed-net use is strongly protective. AmJTrop Med Hyg 2000, 63(3–4):184-188.
• [5]Rijal S, Boelaert M, Regmi S, Karki BMS, Jacquet D, Singh R, Chance ML, Chappuis F, Hommel M, Desjeux P, Van der Stuyft P, Le Ray D, Koirala S: Evaluation of a urinary antigen-based latex agglutination test in the diagnosis of kala-azar in eastern Nepal. Trop Med Int Health 2004, 9(6):724-729.
• [6]Joshi A, Narain JP, Prasittisuk C, Bhatia R, Hashim G, Jorge A, Banjara M, Kroeger A: Can visceral leishmaniasis be eliminated? J Vector Borne Dis 2008, 45(2):105-111.
• [7]Boelaert M, Meheus F, Sanchez A, Singh SP, Vanlerberghe V, Picado A, Meessen B, Sundar S: The poorest of the poor: a poverty appraisal of households affected by visceral leishmaniasis in Bihar, India. Trop Med Int Health 2009, 14(6):639-644.
• [8]Schenkel K, Rijal S, Koirala S, Vanlerberghe V, Van der Stuyft P, Gramiccia M, Boelaert M: Visceral leishmaniasis in south-eastern Nepal: A cross-sectional survey on Leishmania donovani infection and its risk factors. Trop Med Int Health 2006, 11(12):1792-1799.
• [9]World Health Organization: Urbanization: an increasing risk factor for leishmaniasis. Wkly Epidemiol Rec 2002, 44:365-370.
• [10]Barnett PG, Singh SP, Bern C, Hightower AW, Sundar S: Virgin soil: the spread of visceral leishmaniasis into Uttar Pradesh, India. AmJTrop Med Hyg 2005, 73(4):720-725.
• [11]Rijal S, Uranw S, Chappuis F, Picado A, Khanal B, Paudel IS, Andersen EW, Meheus F, Ostyn B, Das ML, Davies C, Boelaert M: Epidemiology of Leishmania donovani infection in high-transmission foci in Nepal. Trop Med Int Health 2010, 15(Suppl.2):21-28.
• [12]Bhattarai NR, Das ML, Rijal S, Van der Auwera G, Picado A, Khanal B, Roy L, Speybroeck N, Berkvens D, Davies CR, Coosemans M, Boelaert M, Dujardin JC: Natural infection of Phlebotomus argentipes with Leishmania and other trypanosomatid in a visceral leishmaniasis endemic region of Nepal. Trans R Soc Trop Med Hyg 2009, 103(11):1087-1092.
• [13]Picado A, Das ML, Kumar V, Kesari S, Dinesh DS Roy L, Rijal S, Das P, Rowland M, Sundar S, Coosemans M, Boelaert M, Davies CR: Effect of Village-wide use of long-lasting insecticidal nets on Visceral Leishmaniasis vector in India and Nepal: A cluster Randomized Trial. PLoS Negl Trop Dis 2010, 49(1):e587.
• [14]Peak J, Rana S, Rai LB: HIV and injecting drug use in selected sites of Terai, Nepal. 2001, 13-15. [Asian Harm Reduction Network and Family Health International Report]
• [15]Government of Nepal, Ministry of Health and Population: National health profile of Nepal. 2004, 1-5. [Report of USAID/National centre for AIDS and STDs control in Nepal]
• [16]Desjeux P: Human leishmaniasis: epidemiology and public health aspects. World Health Stat Q 1992, 45(2–3):267-275.
• [17]Molina R, Gradoni L, Alvar J: HIV and the Transmission of Leishmania. Ann Trop Med Parasitol 2003, 97(Suppl. 1):S29-S45.
• [18]Boelaert M, Rijal S, Regmi S, Singh R, Karki B, Jacquet D, Chappuis F, Campino L, Desjeux P, Le Ray D, Koirala S, Van der Stuyft P: A comparative study of the effectiveness of diagnostic tests for visceral leishmaniasis. AmJTrop Med Hyg 2004, 70(1):72-77.
• [19]Rijal S, Yardley V, Chappuis F, Decuypere S, Khanal B, Singh R, Boelaert M, De Doncker S, Croft S, Dujardin JC: Antimonial treatment of visceral leishmaniasis: are current in vitro susceptibility assays adequate for prognosis of in vivo therapy outcome? Microbes Infect 2007, 9(4):529-535.
• [20]Rijal S, Bhandari S, Koirala S, Singh R, Khanal B, Loutan L, Dujardin JC, Boelaert M, Chappuis F: Clinical risk factors for therapeutic failure in Kala-azar patients treated with pentavalent antimonial in Nepal. Trans R Soc Trop Med Hyg 2010, 104(3):225-229.
• [21]Picado A, Das ML, Kumar V, Dinesh DS, Rijal S, Singh SP, Das P, Coosemans M, Boelaert M, Davies C: Phlebotomus argentipes seasonal pattern in India and Nepal. J Med Entomol 2010, 47(2):283-286.
• [22]Dinesh DS, Das P, Picado A, Davies C, Speybroeck N, Boelaert M, Coosemans M: The efficacy of indoor CDC light traps for collecting the sand fly Phlebotomus argentipes, vector of Leishmania donovani. Med Vet Entomolol 2008, 22(2):120-123.
• [23]Cerbino Neto J, Loureiro Werneck G, Henrique Nery Costa C: Factors associated with the incidence of urban visceral leishmaniasis: an ecological study in Teresina, Piaui State, Brazil. Cad Saude Publica 2009, 25(7):1543-1551.
• [24]Albuquerque PL, Silva Júnior GB, Freire CC, Oliveira SB, Almeida DM, Silva HF, Cavalcante Mdo S, Sousa Ade Q: Urbanization of visceral leishmaniasis (Kala-azar) in Fortaleza, Ceará, Brazil. Pan Am J Public Health 2009, 26(4):330-333.
• [25]Raina S, Mahesh DM, Kaul R, Satindera KS, Gupta D, Sharma A, Thakur S: A new focus of visceral leishmaniasis in the Himalayas, India. J Vector Borne Dis 2009, 46(4):303-306.