A famine weakens body resistance and leads to increases in infectious diseases, especially cholera, dysentery, malaria, and smallpox. Human response to famine could spread the disease as people migrated in search of food and work. On the other hand, railways also had a separate impact on reducing famine mortality by taking people to areas where food was available, or even out of India. By generating broader areas of labor migration and facilitating the massive emigration of Indians during the late 19th century, they provided famine-afflicted people the option to leave for other parts of the country and the world. By the 1912–13 scarcity crisis, migration and relief supply were able to absorb the impact of a medium-scale shortage of food. Drèze concludes, "In sum, and with a major reservation applying to international trade, it is plausible that the improvement in communication towards the end of the nineteenth century did make a major contribution to the alleviation of distress during famines. However, it is also easy to see that this factor alone could hardly account for the very sharp reduction in the incidence of famines in the twentieth century".