In March 2012, a one week course in Medical Entomology, Parasitology, Immunology and Molecular Biology was held at the University of Ngaoundéré.
Part of the Cameroon-Excursion 2012 shall be a teaching course on Medical Entomology & Parasitology at the University of Ngaoundéré, where the 10 students from Tübingen shall participate together with 40 master-students from Ngaoundéré. During one week, teaching sessions shall take place in the morning and excursions to field in the afternoon. A major component shall be the microscopic examination and identification of vectors and parasites by microscopy and molecular techniques. We now have received a loan of 7 Leitz microscopes from the Tübingen Institute of Tropical Medicine to use them for this excursion.
During her stay in Ngaoundéré, Silke van Hoorn from the Bernhard-Nocht-Institut in Hamburg isolated about 2 million of Onchocerca ochengi microfilariae from the skin of cattle (skin samples from the slaughterhouse) and kept them in-vitro to obtain excretory-secretory products (ESPs) for further bio-molecular examinations. These microfilariae had to be separated from those of Onchocerca gutturosa, which also dwell in the skin. This is difficult.
Therefore another option was also tried by Achille Paguem, a Camerooninan student working in our lab: To isolate living microfilariae from the uterus of gravid female worms. Although those intrauterine (i.u.) microfilariae may not be fully mature, they are free from non-O. ochengi contamination. Achille has harvested about 800.000 i.u. microfilariae up-to-now.
Simulium damnosum s.l. blackflies attack man, cattle and game animals. In order to study the hostfinding behaviour and to develop traps for blood-hungy flies, we constructed a number of automatic traps. => Read more
The dissecting microscope, Kalip has been using to examine Simulium flies for filarial infections, has been the oldest in our lab: It was bought in 1976 and shipped to Cameroon directly from Switzerland. For 35 years, the microscope has served in the humid rain-forest and dusty savannah. Its mechanical parts are still looking very fine, but the optics suffered from heavy fungal infections. We were happy to have received a second-hand M5 dissection microscope, of the same age, but with clean optics for very little money. Mr Schneider, the skillfull mechanics of our Zoological Institute in Tübingen, replaced one missing screw. It shall now serve for many years to come!
It is now 25 years that lake Nyos in the Nord-West Province released a toxic cloude of volcanic gazes that killed 1.700 people.
Spiegel-Online commemorates this disaster: http://einestages.spiegel.de/static/topicalbumbackground/23352/toedliche_wolke_aus_dem_see.html
Volcanic activities still continue at Mount Cameroon. During its last eruption a flow of lava of 16 km almost reached the coast.
The volcanic lava still smoking in 2002
This is likely for the first time that you see a microfilaria moving in its natural way, as it wanders through the skin. It was made posible by embedding the living microfilariae in a medium soft enough to allow movement and strong enough to provide a solid ground for its movements. One can see how it uses its tail to move ahead. Any macrophages etc. trying to attack on its cuticula, can easily be sweeped off.
In most cases one sees a living microfilaria, it is in a drop of saline, and the microfilaria moves on the spot by helpless wrigglings, but without making any distance.
Am Donnerstag, den 14. Oktober berichtet Albert im Zoologischen Kolloquium über seine Arbeit in Kamerun:
“Charakterisierung der Filarien des Zebu-Rindes in Zentralafrika, sowie deren Vektoren mittels morphologischer, genetischer und epizootiologischer Analyse”
Im Hörsaal E3A07 im E-Bau (Zoologie); Auf der Morgenstelle: 9.15-10.00 Uhr
Gäste herzlich willkommen!
David Ekale has been trained as a laboratory assistant in our various research projects since 1984. He is now a part-time student in Nsukka, Nigeria and reports of his experiences there.
During wor work with the Programme Onchocercoses in Cameroon (1984 to 1987 in Kumba, then in Ngaoundere) I learned many entomological and parasitological techniques, like dissections of Simulim damnosum flies, morphometric description of adult flies, identification of third stage larvae and microfilaria species. cryopreservation of microfilaria species, intra-thoracic injection of microfilaria in vector flies, cytotaxonomy of the Simulium damnosum complex, embryogram analysis etc. To enlarge my scientific background and to learn more about biology and research methods, I inscribed as a part-time student at the Nsukka-University in Nigeria. Here are my impressions as a student of an African university:
My experience in Nigeria
My study destination Nigeria is a huge country with over 150 million inhabitants. Amazing indeed, because despite the huge oil deposits making it one of the richest country in Africa it is still rated a poor country with less than a dollar per person per day; problems arising mainly from leadership style, poor management and especially corruption has a negative impact in the country’s economy. It is like a magnified version of what is happening in most African countries.
Just published, see:
Onchocerca volvulus, the causative agent of river blindness, is transmitted through the black fly Simulium damnosum s.l., which breeds in turbulent river waters. To date, the number of flies attacking humans has only been determined by standard fly collectors near the river or the village. In our study, we counted the actual number of attacking and successfully feeding S. damnosum s.l. flies landing on individual villagers during their routine day-time activities in two villages of the Sudan-savannah and rainforest of Cameroon. We compared these numbers to the number of flies caught by a standard vector-collector, one positioned near the particular villager during his/her daily activity and the other sitting at the nearest Simulium breeding site.
Using these data obtained by the two vector-collectors, we were able to calculate the Actual Index of Exposure (AIE). While the AIE in the savannah was on average 6,3%, it was 34% in the rainforest. The Effective Annual Transmission Potential (EATP) for individual villagers was about 20 fold higher in the rainforest compared to the savannah.
Here we show for the first time that it is possible to determine the EATP. Further studies with more subjects are needed in the future. These data are important for the development of future treatment strategies.