_Productivity Loss Per Case_ It is important to note that the benefits accruing from the availability of more productive labor days (as a result of reduction in the number of cases of Guinea worm) is not easily estimated. Since transmission occurs seasonally, usually coinciding with the period of peak agricultural labor demand, there is a significant adverse impact on agricultural productivity. The methodology for computing the enhanced productivity of labor as a result of GDEC is as follows. We assume that production of agricultural output is represented in the form of a Cobb-Douglas production function: Y _= AEaKb.l_<sup>_7_</sup> Denote E as the effective labor force (in efficiency units 8) without GDEC. One non-infected worker is assumed to supply one year of productive labor in any given year. An infected worker, due to disease-related incapacitation, is assumed to provide _less than_ one year of productive labor in any given year.<sup>19</sup> The prevention of the loss in productive labor time due to Guinea worm infection is the estimated benefit accruing from GDEC.

Every case of dracunculiasis prevented is projected to add k worker-years of productive labor input time in a given year. This degree of incapacitation k may be expressed in terms of the percentage of labor days per year not worked as a result of infection. As mentioned earlier, a review of twelve published studies yielded an average duration of disability from infection of about 8 weeks, with estimates ranging from 2 to 20 16 weeks. This implies that over 20% of annual work-time is lost per case of infection. In order to be conservative, we assume that on average 5 weeks of production time is lost per case of Guinea worm: a loss of 12.5% of annual work time. We elect a conservative estimate as a benchmark to allow for the possibility that other members belonging to the households of infected individuals may pick up some of the slack in income generation during the period of disability. Furthermore, there may be attempts at long-term

- 17 See footnote 13 for additional details.

- 18 We are measuring the labor force _E_ in terms of the labor service inputs (i.e., time worked) instead of in terms of natural units (i.e., number of workers).

- 19 The framework is similar to that in Cuddington (1993). The effective labor force, in the absence of GDEC, may therefore be decomposed as the sum of the labor input supplied by infected and noninfected individuals in any given year. If z is the proportion of the labor force _L_ that is infected in any given year then the effective labor force _E_ may be characterized as: _E = (1-z) L + z (1-k) L,_ where (1- _z) L_ is the labor supplied by non-infected workers and _z (1-k) L_ is the labor supply of infected workers; _k_ (taking a value between 0 and 1) represents the fraction of work year _lost_ per Guinea worm-stricken worker. In the presence of GDEC, the effective labor force _EG_ is similarly given by: _EG = (I-ZG) L + ZG (1-k) L,_ where _ZG_ is the fraction of the labor force infected with dracunculiasis in a given year. With GDEC, _ZG_ is progressively lower than z. The incremental labor input available as a result of GDEC is given by _(EG - E)_ or _k(z- zG)L,_ where _(z- zG)L_ is simply the number of cases of Guinea worm prevented due to GDEC in the productive segment of the population. Therefore, (z- _zdL_ times k gives us the additional productive labor input available as a result of reducing the incidence of dracunculiasis.

- 20 This is assuming a 40 week work-year, given the seasonality of agricultural production and its coincidence with disease transmission.

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