Dynamics of people's socio-economic status in the face of schistosomiasis control interventions in Ukerewe district, Tanzania.

There is a paucity of research on micro-level assessment of the dynamics of socio-economic status following health interventions. The use of household asset data to determine wealth indices is a common procedure for estimating socio-economic position in low-income countries. Indeed, in such settings information about income is usually lacking and the collection of individual consumption or expenditure data would require in-depth interviews, posing a considerable risk of bias. In this study, we determined the socio-economic status of 159 households in a village in north-western Tanzania before and 1 year after participatory hygiene and sanitation transformation (PHAST) intervention to control schistosomiasis. We constructed a household 'wealth index' based on durable assets ownership (e.g. bicycle and radio) and household characteristics dealing with ownership of land and house construction features (e.g. type of walls and roof). We employed principal components analysis and classified households into wealth quintiles. The study revealed that asset variables with positive factor scores were associated with higher socio-economic status, whereas asset variables with negative factor scores were associated with lower socio-economic status. Overall, households which were rated as the poorest and very poor were on the decrease, whereas those rated as poor, less poor and the least poor were on the increase after PHAST intervention. This decrease/increase was significant. The median shifted from -0.761 to -0.448, and the mean from -0.204 (standard deviation (SD) 1.924) to 0.193 (SD 2.079) between pre- and post-intervention phases. The difference in socio-economic status of the people comparing the pre- and post-intervention phases was highly statistically significant (p<0.001). This observation was confirmed by a multinomial model with a random effect on the households. We argue that significant changes in the socio-economic status observed in our study are attributable to the PHAST intervention, despite other sporadic interventions against schistosomiasis.