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  Indian J Med Microbiol
 

Figure 2: Kala-azar re-emerges whenever the effect of dichlorodiphenyltrichloroethane (DDT) diminishes. In the period under study (1977-2011), DDT spray was carried out three times (1, 2 and 3) when visceral leishmaniasis (VL) cases flared up. The first spray operation was carried out in 1977, 1978 and discontinued in 1979. The effect of DDT was persistent up to 1982.[18] During this period the VL cases declined (green arrow 4) from as high as 41,953 in 1978 to 14,388 in 1982.[21] When the cases peaked an ever high level of 77,099[16] the second spray operation was started, continued through 1992-1994 and discontinued in 1995 and the effect was persistent up to 2001.[18] In the corresponding period, the VL cases declined from 77,099 in 1992 to 12,176 in 2001[16] (green arrow 5). Third spray operation was carried out in the mid 2007 with corresponding declining [green arrow 6] of cases from 44,508 to 24,169 in 2009.[17] But this decline was only short lived and the cases started to resurge to 25,060 in 2010 and 33,108 in 2011[17] (red arrow 9). After the withdrawal of DDT spray and fading residual effect of sprayed DDT, the VL started to re-emerge as happened in 1983 and 2003 (red arrow 7 and 8). Although reports of improper[11] spray with insufficient concentration of DDT,[24,25] no data is presently available about withdrawal of spray that started in 2007. The declining of cases (green arrows) always correlates with corresponding DDT spray and its residual effect periods. The absence of DDT spray and no residual effect always correlates with the resurgence of cases. Surprisingly, the deaths did show any correlation with DDT spray operations

Figure 2: Kala-azar re-emerges whenever the effect of dichlorodiphenyltrichloroethane (DDT) diminishes. In the period under study (1977-2011), DDT spray was carried out three times (1, 2 and 3) when visceral leishmaniasis (VL) cases flared up. The first spray operation was carried out in 1977, 1978 and discontinued in 1979. The effect of DDT was persistent up to 1982.[18] During this period the VL cases declined (green arrow 4) from as high as 41,953 in 1978 to 14,388 in 1982.[21] When the cases peaked an ever high level of 77,099[16] the second spray operation was started, continued through 1992-1994 and discontinued in 1995 and the effect was persistent up to 2001.[18] In the corresponding period, the VL cases declined from 77,099 in 1992 to 12,176 in 2001[16] (green arrow 5). Third spray operation was carried out in the mid 2007 with corresponding declining [green arrow 6] of cases from 44,508 to 24,169 in 2009.[17] But this decline was only short lived and the cases started to resurge to 25,060 in 2010 and 33,108 in 2011[17] (red arrow 9). After the withdrawal of DDT spray and fading residual effect of sprayed DDT, the VL started to re-emerge as happened in 1983 and 2003 (red arrow 7 and 8). Although reports of improper[11] spray with insufficient concentration of DDT,[24,25] no data is presently available about withdrawal of spray that started in 2007. The declining of cases (green arrows) always correlates with corresponding DDT spray and its residual effect periods. The absence of DDT spray and no residual effect always correlates with the resurgence of cases. Surprisingly, the deaths did show any correlation with DDT spray operations