Although NMND excretion was alsoincreased during Giardia infection, the TCA cycle activity was not.Instead, during Giardia infection, there was an accumulation ofcis-aconitate, a precursor to the irreversible firstNAD-requiring enzyme isocitrate dehydrogenase (IDH) in the TCA cycle. The gene discussed is IDH3A; the disease is giardiasis.