Without doubt, cases where disease was introduced deliberately into populations would count. I can't see how simply introducing diseases to a new continent would count as deliberate genocide, although this is small comfort to native populations. The Europeans didn't particularly want the diseases either, and had no idea how they were spread through most of this history.

This is discussed on the source I posted below:

Not to be overlooked is that democide associated with the clash of civilizations and in particularly the European conquest of the Americas. There is no ambiguity about the outright massacres that occurred, such as the Puritan killing of 500-600 Pequot Indians at Mystic Fort in 163768 and the French annihilation of perhaps 1,000 Nanchez Indians in the lower Mississippi after defeating them in 1731. As everyone knows, such also occurred with the post-conquest expansion of national frontiers, as in the United States. Although cowboy and Indian movies leave the impression that Indians were massacred by the tens of thousands, actual body counts show otherwise. To consider one notorious massacre, in 1864 citizen and military troops enlisted from the Colorado territory and led by Colonel John Chivington surrounded and surprised Cheyenne at Sand Creek in the Colorado Territory. Two-thirds of them women and children, the Indians tried to surrender and parley, but all were killed without mercy, their bodies being scalped and mutilated. In total from 70 to 600 were massacred, the latter the upper estimate of the Colonel; 130 killed seems closer to the truth. It was argued that this massacre did not reflect government policy, and it was the subject of army and congressional investigations. But other than Chivington resigning his commission, no one was punished. Just to note the other most well-known massacres by Calvary: at Washita 103 Cheyenne were killed in 1868; in 1870 at Piegan Village 173 Indians were killed; and at Wounded Knee in 1890 it was possibly 146 Sioux. Also often cited is the Bear River Massacre of 1863 in which 250 Shoshoni were wiped out. This began as a battle between Indians and soldiers, but degenerated into a slaughter of helpless and wounded Indians.

While these were the largest American massacres, there undoubtedly were numerous small ones. Moreover, many Indians were killed by vigilantes while local government looked the other way, or were murdered individually by settlers. Taking all the army-Indian battles and massacres into account, probably no more than some 3,000 Indians were killed in the years 1789 to 1898. Settlers and vigilantes likely killed a thousand more. Since many of these Indians were killed in pitched battles, it seems very unlikely that the number of Indians massacred outright by Calvary and settlers in the American West could have been more than 4,000, and was probably a good number less. But this is not the whole story. Many Indians also died from barbarous mistreatment or conditions purposely forced upon them.

For example there was the fate of the Californian Yuki Indians. Originally having a population of around 3,500, in a little more than thirty years its numbers fell to about 400 through "kidnapping, epidemics, starvation, vigilante justice, and state sanctioned mass killing." Moreover, there was the so-called Trail of Tears deaths. In the 1835 treaty of New Echota with the U.S. government Cherokee leaders of a minority faction, and without the approval of the majority, agreed to the nation moving out of Georgia to West of the Mississippi River. Although many prominent Americans publicly opposed such a deportation, in 1838 President Van Buren ordered the army to enforce the treaty. At gun point the Cherokees were thus made to trek westward to Oklahoma in the winter of 1838-39. The resulting exposure and disease killed off nearly 25 percent of the tribe, or about 4,000 people. While the Federal Government's responsibility is mitigated by the treaty, the cruelty of the enforcement amounts to indirect massacre. It was democide. Perhaps overall, considering these and other cases and including massacres, by 1900 some 10,000 to 25,000 Indians may have been killed.

But these estimates are only a fraction of the overall democide among Indians that inhabited all the Americas. Before the conquest of the New World the Indian population may have numbered from 8,000,000 to 110,000,000; perhaps even 145,000,000. A moderate population estimate consistent with the latest research is of 55,000,000 Indians. Almost totally as a result of several waves of disease carried to the Americas by the conquering and colonizing Europeans, the Indian population dropped steeply by tens of millions, even possibly by as much as 95 percent. In Mexico alone the Indian population may have fallen by 23,000,000 to under 2,000,000. Including those Indians who were killed in warfare and democide, perhaps 60,000,000 to 80,000,000 Indians of Central and South American and the Caribbean died as "a result of the European invasion."

Judging what proportion of this mammoth toll constituted democide by the invading armies and colonists is hardly better than picking a number out of the air. No doubt there was much indiscriminate and outright murder. No doubt conditions were forcibly imposed on whole tribes that led to their rapid near extinction. No doubt large numbers of Indians died from inhuman treatment, especially under forced labor. And no doubt in some cases disease may have been knowingly spread. But even Professor David Stannard, author of the American Holocaust, who clearly blames Europeans for many of these deaths, is unwilling to give even a rough approximation of the "genocide." I found one overall estimate of 15,000,000 Indians killed in what appears to be democide, but this figure is given without citation or elaboration. In any case, judging by the bloody history of this period of colonization throughout the Americas, a democide of 2,000,000 would seem a rough minimum and 15,000,000 dead a maximum. Even if these figures are remotely true, then this still make this subjugation of the Americas one of the bloodier, centuries long, democides in world history.

Just as a point of perspective, in the first 70 years of its regime, the Soviet Union--not included in the display in the article--murdered or starved over 60 million of its own people.