Ecology of Infectious Diseases

Science Center Objects

The public is most familiar with parasites' role in spreading infectious diseases to people and domestic animals. In tropical developing countries, malaria, schistosomiasis, and other infectious diseases cause significant human suffering. While most related studies focus on treating patients, Dr. Kevin Lafferty is studying how ecology of the local environment affects transmission of infectious diseases.

A snapshot of an interactive display of salt marsh parasites in Carpinteria Salt Marsh Nature Park.
Salt marsh parasites of Carpinteria Salt Marsh Nature Park.

Determinants of Parasite Populations in an Estuarine System

California estuaries are defined systems (you know when you are in or out of an estuary), accessible at low tide, distributed across a range of latitude and human influence, have well-known and identifiable species, and are of considerable concern due to the wildlife habitat and ecosystem services (filtering out toxins from water, etc.) they provide, making them ideal sites for scientific projects. Three decades of study in these systems have revealed that parasites are abundant and important in estuarine food webs. The background information gathered on parasites in these systems makes it possible to address a range of previously unanswered questions about the role of parasites in natural ecosystems.


Assisting River Prawn Restoration Along the Senegal River

Large river prawns like Macrobrachium vollenhovenii are valuable to fisheries and important to riverine ecosystems. However, because river prawn larvae grow up in downstream estuaries before migrating upstream as juveniles, dams can limit upstream populations. Along the Senegal River, M. volenhovenii was once fished as far as 800 km upstream in Kayes, Mali. Now, river prawns are rare above the Diama Dam and are fished in reduced numbers downstream. Reduced prawn numbers below the dam could, in part, be related to habitat changes or over fishing, while the most likely explanation for the prawns’ rarity upstream is that the dam blocks migrating juveniles. Restoring prawns above the dam should have several benefits, including reducing schistosomiasis, a parasitic disease that passes from freshwater snails to humans, causing anemia and fatigue among other symptoms. This restoration project could also increase food for birds and fishes, control nuisance aquatic plants, and improve fisheries. To restore prawn populations above Diama requires that juvenile prawns be able to complete their upstream migration. Along with colleagues in Senegal, Stanford University, University of California, Santa Barbara, and elsewhere, Dr. Kevin Lafferty has been collaborating on strategies to restore river prawns. The project’s focus is to design a prawn passage that will help larval prawns migrate up river where they can prey on the snails that transmit schistosomiasis.

A photo of the Diama Dam on the Senegal River, West Africa
A photo of the Diama Dam on the Senegal River, West Africa.