A field report from Kenya by Liverpool PhD student Sara Silva Pereira, who was funded by a BSP International Training and Fieldwork Award.
Finding Trypanosoma congolense in Busia, Western Kenya
I was starting the second year of my PhD when my supervisor suggested a trip to Kenya to collect blood samples from cattle naturally infected with Trypanosoma congolense. I finally made it there in the beginning of my final year for a month-long stay.
Animal African Trypanosomiasis is an endemic disease in 37 sub-Saharan countries that has a significant negative effect on both animal health and livestock productivity. It is caused by trypanosome blood parasites (Trypanosoma spp.), transmitted by the bite of tsetse flies (Glossina spp.), and can result in substantial anaemia, weight loss and ultimately death of the infected animal. Efforts to develop effective prophylaxis have been undermined by the mechanism of antigenic variation, employed by the parasite for immune evasion. Antigenic variation is characterised by the sequential substitution of cell surface antigens, compromising the effectivity of an antibody-based response and thus leading to chronic infection and transmission likelihood.
In this project, I was lucky enough to work within the DVS-ILRI laboratory in Busia, which is part of a collaboration between the International Livestock Research Institute (ILRI) and the University of Liverpool through Professor Eric Fèvre. There, the veterinary surgeon Dr Maseno Cléophas was ready to coordinate and assist the project.
Sara making blood smears from an infected cow
The DVS/ILRI lab in Busia
We screened 900 cows in all sub-counties for trypanosomiasis by microscopic analysis of thin blood smears and high centrifugation technique. We collected blood from each positive animal every week, for 4 weeks, and purified the parasites from the blood using a DEAE cellulose column. From the recovered parasites, we extracted nucleic acids and protein, which will be used to identify and quantify transiently-expressed antigen genes and to identify the active cell surface antigen, in an attempt to better understand the relationship between genetics and antigenic switching in natural infections. At the end of the project, the animals involved were treated for trypanosomiasis and all animals screened were dewormed and given multivitamin supplements.
The most difficult part of the project was logistics. Simple things like getting a car to work in the morning, getting the farmers to pick up the phone so we could find them and the animals, having electricity to run the centrifuge, and of course, the dirt roads often flooded by overnight rains. On the bright side, I don’t think I’ll get car sick in Europe anymore! As the locals were constantly reminding me, “This is the real Kenya” and, with all its peculiarities, it is a magnificent country indeed.
It wasn’t all work. On the second weekend, I did manage to escape to a beautiful cottage house in Kericho, where I met people from ILRI working in Nairobi. I got to ride a horse, see a waterfall and walk through sugar cane plantations praying silently not to find snakes. The remaining weekends were spent catching up on my book waiting list and, of course, sunbathing in the nearby hotel swimming pool with the local children.
Through the International Training and Fieldwork Award, the BSP has allowed me to personally witness the difficulties and rewards of field work in remote areas, including all the logistics; to have a better understanding on how farming works in Kenya; and to further develop people and laboratory skills that would not be possible in the comfort of our highly-equipped institute in Liverpool. More importantly, the BSP and the BBSRC, who funded the rest of the project, have allowed the collection of precious materials that will be used to understand antigen-switching patterns in natural infections as well as to show an application for a variant antigen profiling methodology we have developed in the first years of my PhD. For all of this, I am deeply grateful.
-Sara Silva Pereira, Post-graduate student, Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool