Diphtheria keeps striking northern Nigeria harder than the rest of the country, and the causes are largely preventable. Vaccination rates in the region trail far behind, leaving many children unprotected against a disease a routine shot can stop. Poverty makes things worse, because families often cannot reach a clinic or pay for care once symptoms show. Crowded housing and poor sanitation give the bacteria more room to spread. Health workers warn the outbreaks will keep coming back until those gaps are fixed.