DOCTORAL RESEARCH
I am part of the Bill and Melinda Gates funded Program for Enhancing the Health and Productivity of Livestock. As part of this program I study a virus called peste des petits ruminants virus, which causes sheep and goat plague. I work with Dr. Ottar Bjørnstad, Dr. Peter Hudson, Dr. Isabella Cattadori, and Dr. Vivek Kapur in collaboration with Tanazanian colleagues Dr. Lughano Kusiluka (Mzumbe University), Dr. Emmanuel Mpolya, and Dr. Joram Buza at the Nelson Mandela African Institute of Science and Technology to study the multi-host disease dynamics and persistence of peste des petits ruminants virus (PPRV) in Tanzania.
The livestock-wildlife interface in northern Tanzania, especially areas near Serengeti National Park and Ngorongoro Crater, is species rich with pastoralists and agropastoralists herding cattle, sheep, and goats on grazing grounds shared with wildlife including African buffalo, wildebeest, and various antelope, bat, and rodent species. I am developing a multi-host model that will describe the system and allow me to test the impact of various seasonal forces on disease dynamics. This model will be informed by a large, age structured serosurvey among sheep and goats in Northern Tanzania collected by my collaborators at the University of Glasgow: Dr. Sarah Cleaveland, Dr. Will de Glanville, and Dr. Brian Willett. PPRV has been selected as one of the next diseases for global eradication, but currently there is much that is unknown about its transmission dynamics in multi-host systems, such as those found in Tanzania. The role of each livestock species and of regional wildlife species in transmission and persistence of PPRV needs to be better understood to help guide eradication campaign efforts. Papers from this work are featured on my Publications Page and here: Herzog, C.M., de Glanville, W.A., Willett, B.J., Kibona, T.J., Cattadori, I.M., Kapur, V., Hudson, P.J., Buza, J., Cleaveland, S., Bjørnstad, O.N. Pastoral production is associated with increased Peste des petits ruminants seroprevalence in northern Tanzania across sheep, goats, and cattle. Epidemiology and Infection 2019; 147: 1–9. doi: 10.1017/S0950268819001262 Herzog, C.M.; de Glanville, W.A.; Willett, B.J.; Cattadori, I.M.; Kapur, V.; Hudson, P.J.; Buza, J.; Swai, E.S.; Cleaveland, S.; Bjørnstad, O.N. Identifying Age Cohorts Responsible for Peste Des Petits Ruminants Virus Transmission among Sheep, Goats, and Cattle in Northern Tanzania. Viruses 2020, 12, 186. doi: 10.3390/v12020186 Herzog, C.M.; de Glanville, W.A.; Willett, B.J.; Cattadori, I.M.; Kapur, V.; Hudson, P.J.; Buza, J.; Swai, E.S.; Cleaveland, S.; Bjørnstad, O.N. Peste des petits ruminants Virus Transmission Scaling and Husbandry Practices That Contribute to Increased Transmission Risk: An Investigation among Sheep, Goats, and Cattle in Northern Tanzania. Viruses 2020, 12, 930. doi: 10.3390/v12090930 These publications were covered in the media here:
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RESEARCH IN ACTION
Catherine tested sheep, goat, and cattle serum samples in the lab using a competitive enzyme linked immunosorbent assay (cELISA) which detects antibodies in the serum. Here, she explains and demonstrates the technique and how she is using it to further her research on peste des petits ruminants virus. |
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SHEEP & GOAT PLAGUE
What is it? Sheep & goat plague infects goats, sheep, and cattle - though to a lesser extent. Sheep & goat plague is caused by the peste des petits ruminants virus (PPRV). This virus is in the Morbillivirus genus, which also includes human measles virus, distemper viruses (canine, phocine, ceteacan), and the now eradicated rinderpest virus which caused the cattle plague. What is the impact of sheep & goat plague? Sheep & goat plague is highly contagious and can cause up to 100% mortality in infected flocks. Currently, sheep & goat plague is present in over 70 countries and threatens ~ 80% of the global sheep and goat population, according to the Food and Agricultural Organization (FAO). Sheep & goat plague has received increased media coverage in recent years from NPR and The Economist, and has raised concerns for conservation as it has decimated saiga antelope populations in Mongolia. Furthermore, PPRV has been found to infect several other ruminant wildlife species. How does it affect humans? Given it's geographical distribution, sheep & goat plague may impact over 330 million farmer's livelihoods, who rely directly on sheep and goats for meat, milk, and income. Without these, poverty, malnutrition, and social and economic instability rises. As women and youth tend to manage sheep and goats, they are most impacted by losses in their flocks due to sheep & goat plague. Imagine a world with out products from sheep and goats, as was done in the bottom video on the right. Luckily, an effective vaccine is available and international organizations such as FAO and OIE are putting together a global control and eradication campaign with a goal of eradicating sheep & goat plague by 2030. |
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