Can onchocerciasis be eliminated? Epidemiological

Can onchocerciasis be eliminated? Epidemiological, entomological
and parasitological studies in a bovine model in Cameroon.
The research Questions of the present project are:
Is the ongoing transmission still high enough to maintain endemicity?
How does the parasite regulate its population density in both the vector and
vertebrate host and how is the adult worm and microfilarial turnover governed in the
bovine host?
How big is the risk that emerging ivermectin resistance may spread?
Is there any gene-flow between O. ochengi and O. volvulus or other local
Onchocerca species and strains.
How many of the adult worms present in a host do contribute to the population of
circulating microfilariae?
The specific objectives are:
1). To study Onchocerca population biology and immunology: will study parasite
population build up in definitive and intermediate hosts and focus on the antigen
recognition: Antibody levels against Onchocerca somatic extract and lead
recombinant antigens (Ov20; NLT1; cystatin and other newly isolated ones).
2). Studies on Onchocerca reproductive biology and phylogeny: SNPs
polymorphisms of various Onchocerca-populations shall bring insights into the coevolution of animal and human Onchocerca species and strains of O. volvulus and O.
ochengi.
3). Epidemiology and Transmission studies to assess the actual annual Onchocerca
transmission potentials (ATP O. ochengi, O. volvulus and others in three different
areas: Menchum valley, Vina du nord and the Adamawa plateau. Molecular genetic
identification of Onchocerca larvae found in the vectors and of adult worms will allow
the understanding of the co-transmission and possible hybridisation of the many
Onchocerca species found in our study area.
Country project Co-ordinator: ACHUKWI Mbunkah Daniel :
Director of Research, Scientific Director of IRAD, Cameroon.
Important project partners in Germany:
Alfons RENZ, Dr. rer. nat. Priv.-Doz. University of Tübingen- Project head
Adrian STREIT, Dr. phil. Priv.-Doz. University Tübingen, working at the Max Planck
Institute in Tübingen
Norbert BRATTIG, Dr. rer. nat. Bernhard Nocht Institut Hamburg, Priv.-Doz at the
Hamburg University
Prof. Eva Liebau, WWU Münster, PD Dr. Minka Breloeur,BNI, Hamburg, Prof.
Christian Betzel and Dr, Makus Perbandt, DESY
Drs. Hoffmann, Metzger & Mordmüller; Loa-loa Projekt in Gabun:Intitut for Tropical
Medicine in Tübingen
Important project partners in Cameroon
Bamenda University: Project partner: Dr Nguemaim NGOUFOU
IRAD and her links with German institutions: hand in hands seeking for
solutions to tropical infectious diseases of animals and man.
The University of Tübingen (www.uni-tuebingen.de) provides the background of
scientific collaboration and field research in Cameroon since 1976 for biologists and
parasitologists (PD Dr. Alfons Renz and Dipl. biol. Albert Eisenbarth). Dr. Wolfgang
Hoffmann at the Institute of Tropical Medicine Tübingen who leads an experienced
group studying rodent filarial models is just one of the fruits of the IRAD- Tübingen
collaboration from the early nineties when he was a student undertaking his field
work in the Veterinary Research Lab in IRAD Wakwa. This has provided internship
framework conditions to over 30 German students since 1988 to date. In general, our
research is parasites and more recently with zoonotic viruses of pigs. A lot more
emphasis is on filarial models, which are representatives for their homologues
relevant in tropical medicine as causative agents for human onchocerciasis and
lymphatic filariasis. The University of Hohenheim (www.uni-hohenheim.de) is strongly
involved in research on tropical livestock farming systems and analysis of genomic
data. Between the Universities of Tübingen and Hohenheim, a formal cooperation
agreement aims at combining research and teaching capacities of the two institutions
located in close proximity. The Tropical Center in Hohenheim (www.troz.de)
additionally supports international cooperation and has a long record of collaboration
with the Animal production and animal health departments of IRAD in the early
nineties in which collaboration with GTZ (Teuscher, Hubert etc.) lead to the
introduction of the farming systems approach in IRAD.
The departments of Biochemistry, university of Bremen (Prof kelm) and University of
Tübingen (Prof Duzenko) has been collaborating during the last three years with the
Veterinary Research lab of IRAD Wakwa on Molecular and parasitological
epidemiology of possible co-infection of humans by human and cattle trypanosomes
in tsetse foci of North and Adamawa, regions-Cameroon. This lead to a Cameroonian
Ph.D student, Claudine Sen Henriette Ngomtcho, undertaking part of her work in
Bremen financed by the German Academic Exchange Service, Deutscher
Akademischer Austauschdienst-DAAD scholarship A/12/97080.
Another newly established partnership is the Bernhard Nocht Institute for Tropical
Medicine (BNI), Hamburg (Dr Norbet Brattig & Prof Erttmann, Dr Minka Breloer). In
this partnership Manchang TK- a veterinarian in IRAD Wakwa undertook studies in
BNI and the university of Mûnster where he is expecting to defend a PhD thesis in
parasite Immunology before December 2014 with Prof Eva Liebau as main
supervisor. A number of scientific staff of these two universities have already spent
short term research working visits in the Veterinary Research lab, IRAD Wakwa in
this win-win partnership..
Publications emanating from these collaborations are more than 50 so far:
A few are listed here below and many others can be read from our project web
site:www.riverblindness.eu
Renz A, Trees AJ, Achukwi D, Edwards D, Wahl G. (1995) Trop Med Parasitol 46: 31-7.
Renz A, Wenk P (2012) Hist. Biology dx.doi.org/10.1080/08912963.2012.692682
Trees AJ., Graham SP, Renz A, Bianco AE & Tanya V (2000): Parasitology 120: 133-142
Wahl G., Achukwi MD, Mbah D, Dawa O, Renz A, (1994): Veterinary Parasitology 52: 297-311.
ACHUKWI, D., W. HARNETT, J. BRADLEY, A, RENZ (2004): Onchocerca ochengi acquisition in zebu
Gudali cattle exposed to natural transmission: parasite population dynamics and IgG antibody
subclass responses to Ov10/Ov11 recombinant antigens. Vet Parasitol. 122(1):35-49.
ACHUKWI, D. W. HARNETT, P. ENYONG, A. RENZ (2007): Successful vaccination against
Onchocerca ochengi in cattle using live Onchocerca volulus infective larvae as an heterologeous
vaccine. Parasite Immunology 29 (3); 113-116. doi:10.1111/j.1365-3024.2006.00917.x
Achukwi, MD. Harnett W, Bradley J, Renz A. (2004) Vet Parasitol 122:35-49.
ACHUKWI, D., W. HARNETT, A. RENZ (2000): Onchocerca ochengi transmission dynamics and the
correlation of O. ochengi microfilaria density in cattle with the transmission potential. Veterinary
Research, 31, 611-621
SEIDENFADEN, R., A. FISCHER, I. BONW, D. EKALE, V. TANYA & A. RENZ (2001): Combined
benefits of annual mass-treatment with ivermectin and zooprophylaxis on the severity of human
onchocerciasis in Northern Cameroon. Trop. Med. Int. Health 6, 715-725.
Vanessa S. de Paula, Matthias Wiele, Afegenwi H. M., Achukwi M.D., Manchang T.K, Jonas SchmidtChanasit. 2013. Hepatitis E Virus Genotype 3 strains in domestic pics, Cameroon. Emerging
infectious Diseases WWW.cdc.gov/eid-vol.19,N° 4, p666—668.
Cornelia Adlhoch, Marco Kaiser, Manchang TK, Norbert Georg Schwarz, Markus Ulrich, Vaessa S. de
Paula, Anna Lowa, Achukwi M.D., Sven Poppert, Jonas Schmidt-Chanasit & Heinz Ellerbrok
2013. Porcine Hokovirus in domestic pigs, Cameroon.
WWW.cdc.gov/eid-vol.19,N° 12, p 2080—2082.
Emerging infectious Diseases
Ndjonka D., Agyare C., Lüersen K., Djafsia1 B., Achukwi D., Nukenine E.N., Hensel A. and Liebau E. (2010). In
vitro activity of Cameroonian and Ghanaian medicinal plants on parasitic (Onchocerca ochengi) and
free-living (Caenorhabditis elegans) nematodes. Cambridge University Press. Journal of
Helminthology, page 1- 9.
Irene
Ajonina-Ekoti, Marc Andre Kurosinski, Abuelhassan ElshazlyYounis, DieudonneNdjonka,
ManchangKingsleyTanyi, Mbunkah Daniel Achukwi, Albert Eisenbarth, Caroline Ajonina, Kai Lüersen,
Minka Breloer, Norbert W Brattig, Eva Liebau (2013). Comparative analysis of macrophage migration
inhibitory factors (MIFs) from the parasitic nematode Onchocerca volvulus and the free-living
nematode Caenorhabditis elegans. Parasitol Res. DOI 10.1007/s00436-013-3513-1.
Klager, S.L.; Watson, A.; Achukwi, M.D.; Hultmark and Hagen H.E. (2002). Humoral immune response of
Simulium damnosum s.l. following filarial and bacterial infections. Parasitology 125, 339-366.
Cross, H.F.; Bronsvoort, B.M.; Wahl G.; Renz, A.; Achukwi, M.D.; & Trees, A.J. (1997). The entry of ivermectin
and suramin into Onchocerca ochengi nodules. Annals of Tropical Medicine and Parasitology, Vol. 91,
No. 4, 393-401.
Renz A., Trees A.J., Achukwi M.D., Edwards G., Wahl G. (1995). Evaluation of Suramin, Ivermectin & CGP
20376 in a new macrofilaricidal drug screen, Onchocerca ochengi in African Cattle. Trop. Med. Parasitl.
Vol. 46 (1): 31- 37.
Manchang T K, Ajonina-Ekoti I , Ndjonka D, Eisenbarth A, Achukwi M D, Renz A, Brattig N W, Liebau E,
Breloer M ( 2014). Immune recognition of Onchocerca volvulus proteins in the human host and
animal models of onchocerciasis.
Journal of Helminthology, page 1 of 12;
doi:10.1017/S0022149X14000224
D. Ndjonka, E.D. Abladam, B. Djafsia, I. Ajonina-Ekoti, M.D. Achukwi and E. Liebau. (2013) Anthelmintic
activity of phenolic acids from the axlewood tree Anogeissus leiocarpus on the filarial nematode
Onchocerca ochengi and drug-resistant strains of the free-living nematode Caenorhabditis elegans.
Journal
of
Helminthology,
(p1-8)
issn
=
{1475-2697},
available on CJO2013. doi:10.1017/S0022149X1300045X.
Some results
A
No. of nodules per animal
120
100
80
60
40
20
0
0
4
8
12
16
20
22
24
26
Exposure period/months
B
No. of mf in skin snips
1000
O.ochengi
O.gutturosa
800
n=10
600
400
200
0
0
4
8
12
16
20
Exposure period/months
22
24
26
Figure 1: Infection levels of calves naturally exposed to Onchocerca infections. Cumulative loads of
nodules (A) and microfilarial levels (B) over a 26 months exposure period to high Simulium and
Culicoides fly bites and O. ochengi and O. gutturosa transmission. Calves were examined for palpable
intradermal nodules (A) and mf levels in skin snips at each time periods, (B), n=10. Each circle
represents nodule loads for a single calve (A) and each circle represents O. ochengi (black) and O.
gutturosa (white) levels in skin snips (B).
Vet Res lab Wakwa
indigenous Gudalii
Photo 1). Inauguration of COBE with His Excellency, the former ambassador of Germany to
Cameroon, Dr. Buchholz and Dr. Achukwi in Tübingen
Photo 2). Presentation of the COBE-project to his Excellence, the Embassador of Cameroon
to Germany and his wife.
Figure 3). German Scientist & Student catch simuliun flies with IRAD Scientist in river Vina du Sud.

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