Flooding and Health Outcomes in Zambia
Presented by:
Theresa Ng'andu
Practice Job Talk
Department of Agricultural and Applied Economics
University of Wisconsin-Madison
Friday, October 2, 2026
12:00 pm-1:30 pm
Taylor-Hibbard Seminar Room (Rm103)
I study the impact of flooding on the incidence of vector-borne diseases such as malaria, and waterborne diseases such as cholera, typhoid, dysentery, and non-typhoid non-dysentery diarrhea in Zambia. I use monthly data on confirmed (tested) cases of malaria and cholera, and clinical (symptom-based) cases of typhoid, dysentery, and non-typhoid non-dysentery diarrhea from the Ministry of Health, and satellite 2-day flood products from NASA MODIS, for 2012 to 2024. I analyze the data at the ward level, which is the smallest administrative boundary in Zambia. I use month-year fixed effects to capture seasonality, ward fixed effects for baseline ward characteristics, and district-by-year fixed effects to control for regional shocks. Estimating Poisson pseudo-likelihood with high-dimensional fixed effects (ppmlhdfe) with lags up to three months, I find that when a ward has an additional day of sustained 3-day flooding, the cumulative effects of such a flood event over three months are 3.7 % or 14 more cases above the baseline number of malaria cases, and for a week of sustained flooding, this effect more than quadruples to 16.5% or 63 cases above the baseline number of malaria cases. For cholera, the percentage of flooded area significantly affects incidence over two months: an additional day when a ward floods 0.1% to 1% of its area increases cholera incidence by 32%. For dysentery, contemporaneous floods matter more, and over 2 months, an additional day of sustained flooding for at least 3 days increases the incidence by 4.5%, and this number rises to about 16% when sustained flooding is at 7 consecutive days. Regarding typhoid, I find that floods have a mitigating or flushing effect on the incidence, and for non-typhoid non-dysentery diarrhea, floods do not have an impact. In this specific context and under these conditions, the findings in this paper are consistent with the public health literature. A back-of-the-envelope calculation on the costs incurred due to the incidence of diseases due to flooding shows that for malaria, in the absence of one additional sustained 3-day flood event, 10 malaria cases can be prevented, and for a lower-bound treatment cost of malaria of $4, this translates to about $40 in prevented costs of treating these cases at a government health facility.