Density Dependence - Implications For Parasite Distribution

Implications For Parasite Distribution

Anderson and Gordon (1982) propose that the distribution of macroparasites in a host population is regulated by a combination of positive and negative density-dependent processes. In overdispersed distributions, a small proportion of hosts harbour most of the parasite population. Positive density-dependent processes contribute to overdispersion of parasite populations, whereas negative density-dependent processes contribute to underdispersion of parasite populations. As mean parasite burden increases, negative density-dependent processes become more prominent and the distribution of the parasite population tends to becomes less overdispersed.

Consequently, interventions that lead to a reduction in parasite burden will tend to cause the parasite distribution to become overdispersed. For instance, time-series data for Onchocerciasis infection demonstrates that 10 years of vector control lead to reduced parasite burden with a more overdispersed distribution.

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