Debrah AY et al. (2006) Filaria J "Assessment of microfilarial loads in the skin of onchocerciasis patients after treatment with different regimens of doxycycline plus ivermectin."

Debrah AY, Marfo-Debrekyei Y, Mand S, Larbi J, Adjei O, Hoerauf A

[Filaria J, 2006]

BACKGROUND: Infection with the filarial nematode Onchocerca volvulus can lead to severe dermatitis, visual impairment, and ultimately blindness. Since the currently used drug, ivermectin does not have macrofilaricidal or strong permanent sterilising effects on the adult worm, more effective drugs are needed to complement the use of ivermectin alone. Wolbachia endosymbiotic bacteria in filariae have emerged as a new target for treatment with antibiotics which can lead to long -term sterilization of the adult female filariae. METHODS: In the Central Region of Ghana, 60 patients were recruited, allocated into four groups and treated with 200 mg doxycycline per day for 2 weeks, 4 weeks, 6 weeks respectively. Untreated patients served as controls. Some of the treated patients and the untreated controls were given 150 microg/kg ivermectin 8 months after the start of doxycycline treatment. RESULTS: A follow up study 18 months post treatment showed that when using doxycycline alone there was a significant reduction of microfilarial (mf) loads in patients treated for either 4 or 6 weeks. However, there was no significant difference between the untreated controls and those given the 2 weeks regimen. Although no significant difference was demonstrated between the 4 and 6 weeks regimens, there was a trend observed, in that, microfilarial reduction appeared to have been greater following the 6 weeks regimen. Twelve months after ivermectin (i.e. 20 months after doxycycline) treatment, 8 out of 11 ivermectin-alone treated patients were mf-positive. In contrast, 1 out of the 7 patients treated for 4 weeks with doxycycline and none of the 4 patients treated for 6 weeks doxycycline (who were available for re-examination) were mf-positive after the combined treatment of doxycycline plus ivermectin treatment. CONCLUSION: Treatment of onchocerciasis with doxycycline for 4 weeks is effective. Nonetheless, mf reduction appeared to be greater in the 6 weeks regimen. It is recommended that until further studies are carried out i.e. 4 weeks treatment with doxycycline is proven equivalent to the 6 weeks, selected groups of onchocerciasis patients should be treated for 6 weeks with doxycycline. As discussed earlier, this treatment should be accompanied by two doses of ivermectin.

Lagatie O et al. (2016) Parasit Vectors "An isothermal DNA amplification method for detection of Onchocerca volvulus infection in skin biopsies."

Merino M, Debrah AY, Batsa Debrah L, Lagatie O, Stuyver LJ

[Parasit Vectors, 2016]

BACKGROUND: Diagnostic procedures for the diagnosis of infection with the nematode parasite Onchocerca volvulus are currently based on the microscopic detection of microfilariae in skin biopsies. Alternative approaches based on amplification of parasitic DNA in these skin biopsies are currently being explored. Mostly this is based on the detection of the O-150 repeat sequence using PCR based techniques. METHODS: An isothermal, loop-mediated amplification method has been designed using the mitochondrial O. volvulus cox1 gene as a target. RESULTS: Analysis of dilution series of synthetic DNA containing the targeted sequence show a non-linear dose-response curve, as is usually the case for isothermal amplification methods. Evaluation of cross-reactivity with the heterologous sequence from the closely related parasites Wuchereria bancrofti, Loa loa and Brugia malayi demonstrated strong specificity, as none of these sequences was amplified. The assay however amplified both O. volvulus and O. ochengi DNA, but with a different melting point that can be used to discriminate between the species. Evaluation of this assay in a set of skin snip biopsies collected in an endemic area in Ghana showed a high correlation with O-150 qPCR and also demonstrated a similar sensitivity. Compared to qPCR, LAMP had a sensitivity of 88.2% and a specificity of 99.2%. CONCLUSIONS: We have developed a sensitive and specific loop-mediated amplification method for detection of O. volvulus DNA in skin biopsies that is capable of providing results within 30min.

Globisch D et al. (2017) Bioorg Med Chem Lett "Validation of onchocerciasis biomarker N-acetyltyramine-O-glucuronide (NATOG)."

Globisch D, Shirey RJ, Eubanks LM, Wanji S, Pfarr KM, Hoerauf A, Debrah AY, Janda KD

[Bioorg Med Chem Lett, 2017]

The Neglected Tropical Disease onchocerciasis is a parasitic disease. Despite many control programmes by the World Health Organization (WHO), large communities in West and Central Africa are still affected. Besides logistic challenges during biannual mass drug administration, the lack of a robust, point-of-care diagnostic is limiting successful eradication of onchocerciasis. Towards the implementation of a non-invasive and point-of-care diagnostic, we have recently reported the discovery of the biomarker N-acetyltyramine-O-glucuronide (NATOG) in human urine samples using a metabolomics-mining approach. NATOG's biomarker value was enhanced during an investigation in a rodent model. Herein, we further detail the specificity of NATOG in active onchocerciasis infections as well as the co-infecting parasites Loa loa and Mansonella perstans. Our results measured by liquid chromatography coupled with mass spectrometry (LC-MS) reveal elevated NATOG values in mono- and co-infection samples only in the presence of the nematode Onchocerca volvulus. Metabolic pathway investigation of l-tyrosine/tyramine in all investigated nematodes uncovered an important link between the endosymbiotic bacterium Wolbachia and O. volvulus for the biosynthesis of NATOG. Based on these extended studies, we suggest NATOG as a biomarker for tracking active onchocerciasis infections and provide a threshold concentration value of NATOG for future diagnostic tool development.

Hoerauf A et al. (2008) Parasitol Res "Effects of 6-week azithromycin treatment on the Wolbachia endobacteria of Onchocerca volvulus."

Adjei O, Buttner M, Buttner DW, Debrah AY, Konadu P, Hoerauf A, Mand S, Marfo-Debrekyei Y

[Parasitol Res, 2008]

The effects of azithromycin treatment on the presence of Wolbachia endobacteria and on the embryogenesis and microfilariae production of Onchocerca volvulus were studied. In 2002, in an endemic area in Ghana, 37 onchocerciasis patients were treated for 6 weeks with azithromycin: 23 patients received 250 mg every day, and 14 took 1,200 mg once a week. After 6 and/or 12 months, all palpable worm nodules were extirpated from 31 treated and nine additional untreated patients, and the presence of Wolbachia and embryogenesis were assessed by immunohistology. In nodules taken 6 months after treatment with either dose and 12 months after 1,200 mg/week, the Wolbachia loads of the worms were not different from those of untreated worms. However, 12 months after the 250-mg/day azithromycin regimen, significantly less female worms (65% compared to 92% untreated ones) presented many Wolbachia, although the reduction was less pronounced than observed in other studies after treatment with doxycycline. Embryogenesis and microfilariae production were not reduced. It is concluded that azithromycin administered alone for 6 weeks at 250 mg/day or 1,200 mg/week is not suitable for treatment of human onchocerciasis. But daily azithromycin should be studied in combination with other drugs and with other doses.

Specht S et al. (2008) Parasitol Res "Efficacy of 2- and 4-week rifampicin treatment on the Wolbachia of Onchocerca volvulus."

Marfo-Debrekyei Y, Hoerauf A, Adjei O, Specht S, Konadu P, Buttner DW, Debrah AY, Mand S

[Parasitol Res, 2008]

The microfilaricidal and temporarily sterilizing drug ivermectin is used for mass treatment of filarial infections. Filariae containing Wolbachia endobacteria can also be treated by the antibiotic doxycycline. The loss of Wolbachia results in sterilization of Onchocerca volvulus and macrofilaricidal effects. Besides doxycycline, other antibiotics may be effective in depleting Wolbachia. A preliminary study on the effects of rifampicin on the endobacteria, embryogenesis and microfilariae production of O. volvulus was carried out in the year 2000 in Ghana. Twenty-six onchocerciasis patients were treated for 2 or 4 weeks with 10 mg/kg/day rifampicin. From 17 treated and nine untreated patients, all palpable nodules were extirpated 1 or 18 months after the start of the study and examined for Wolbachia and embryogenesis using immunohistology. One and 18 months after rifampicin treatment, the proportion of Wolbachia-positive worms was significantly reduced compared to the untreated group. In patients treated 4 weeks with rifampicin, only 21% and 18% of living female filariae contained Wolbachia after 1 and 18 months, respectively, compared to 92% in the untreated patients. The reduction of Wolbachia after 2 weeks rifampicin was less but also significant. Embryogenesis and microfilariae production were reduced after 4 weeks rifampicin treatment, rendering rifampicin an antibiotic with anti-wolbachial efficacy in human onchocerciasis. This treatment is less efficient than treatment with 6 weeks doxycycline, but might be an alternative for cases that cannot be treated with doxycycline, e.g. children, or might be further developed for combination therapy.

Arndts K et al. (2014) PLoS Negl Trop Dis "Immunoepidemiological profiling of onchocerciasis patients reveals associations with microfilaria loads and ivermectin intake on both individual and community levels."

Klarmann Schulz U, Mand S, Layland LE, Martin C, Kwarteng A, Debrah AY, Hoerauf A, Arndts K, Batsa L, Taylor M, Adjei O, Specht S, Tamarozzi F

[PLoS Negl Trop Dis, 2014]

Mass drug administration (MDA) programmes against Onchocerca volvulus use ivermectin (IVM) which targets microfilariae (MF), the worm's offspring. Most infected individuals are hyporesponsive and present regulated immune responses despite high parasite burden. Recently, with MDA programmes, the existence of amicrofilaridermic (a-MF) individuals has become apparent but little is known about their immune responses. Within this immunoepidemiological study, we compared parasitology, pathology and immune profiles in infection-free volunteers and infected individuals that were MF(+) or a-MF. The latter stemmed from villages in either Central or Ashanti regions of Ghana which, at the time of the study, had received up to eight or only one round of MDA respectively. Interestingly, a-MF patients had fewer nodules and decreased IL-10 responses to all tested stimuli. On the other hand, this patient group displayed contrary IL-5 profiles following in vitro stimulation or in plasma and the dampened response in the latter correlated to reduced eosinophils and associated factors but elevated neutrophils. Furthermore, multivariable regression analysis with covariates MF, IVM or the region (Central vs. Ashanti) revealed that immune responses were associated with different covariates: whereas O. volvulus-specific IL-5 responses were primarily associated with MF, IL-10 secretion had a negative correlation with times of individual IVM therapy (IIT). All plasma parameters (eosinophil cationic protein, IL-5, eosinophils and neutrophils) were highly associated with MF. With regards to IL-17 secretion, although no differences were observed between the groups to filarial-specific or bystander stimuli, these responses were highly associated with the region. These data indicate that immune responses are affected by both, IIT and the rounds of IVM MDA within the community. Consequently, it appears that a lowered infection pressure due to IVM MDA may affect the immune profile of community members even if they have not regularly participated in the programmes.

Attout T et al. (2009) PLoS One "Lymphatic vascularisation and involvement of Lyve-1+ macrophages in the human onchocerca nodule."

Martinez V, Adjei O, Denece G, Hoerauf A, Debrah AY, Attout T, Wanji S, Mand S, Marfo-Debrekyei Y, Boussinesq M, Bain O, Specht S, Martin C

[PLoS One, 2009]

Onchocerciasis, caused by the filarial nematode Onchocerca volvulus, is a parasitic disease leading to debilitating skin disease and blindness, with major economic and social consequences. The pathology of onchocerciasis is principally considered to be a consequence of long-standing host inflammatory responses. In onchocerciasis a subcutaneous nodule is formed around the female worms, the core of which is a dense infiltrate of inflammatory cells in which microfilariae are released. It has been established that the formation of nodules is associated with angiogenesis. In this study, we show using specific markers of endothelium (CD31) and lymphatic endothelial cells (Lyve-1, Podoplanin) that not only angiogenesis but also lymphangiogenesis occurs within the nodule. 7% of the microfilariae could be found within the lymphatics, but none within blood vessels in these nodules, suggesting a possible route of migration for the larvae. The neovascularisation was associated with a particular pattern of angio/lymphangiogenic factors in nodules of onchocerciasis patients, characterized by the expression of CXCL12, CXCR4, VEGF-C, Angiopoietin-1 and Angiopoietin-2. Interestingly, a proportion of macrophages were found to be positive for Lyve-1 and some were integrated into the endothelium of the lymphatic vessels, revealing their plasticity in the nodular micro-environment. These results indicate that lymphatic as well as blood vascularization is induced around O. volvulus worms, either by the parasite itself, e.g. by the release of angiogenic and lymphangiogenic factors, or by consecutive host immune responses.

Hoerauf A et al. (2009) Parasitol Res "Efficacy of 5-week doxycycline treatment on adult Onchocerca volvulus."

Specht S, Buttner M, Buttner DW, Brattig N, Hoerauf A, Bandi C, Debrah AY, Mand S, Marfo-Debrekyei Y, Fimmers R, Konadu P, Batsa L, Adjei O

[Parasitol Res, 2009]

The effects of 5-week doxycycline treatment on the depletion of Wolbachia endobacteria from Onchocerca volvulus, on the interruption of embryogenesis and on microfilariae production, and with regard to macrofilaricidal activity were studied. In 2003, in an endemic area in Ghana, 22 onchocerciasis patients received 100 mg/day doxycycline for 5 weeks. Two years after the start of the study, 20 treated and ten untreated patients were nodulectomized and skin microfilariae were counted. The onchocercomas were examined by immunohistology for the presence of Wolbachia, embryogenesis, and vitality of adult filariae. The latter two parameters were further assessed by alternating logistic regression analysis, taking into account the dependency of worms and nodules in patients. Doxycycline resulted in depletion of Wolbachia and in complete interruption of embryogenesis in all worms that were assumed to have been present during treatment. In the treated patients, only 51% of the female worms were alive, compared to 84% in the untreated patients, indicating a moderate but distinct macrofilaricidal activity of doxycycline at this dose. It is concluded that, in areas with ongoing transmission, doxycycline cannot replace regular ivermectin mass treatment because new infections would require repeated rounds of doxycycline. However, doxycycline can be used for the treatment of individuals outside transmission areas, in foci where ivermectin resistance may occur, and in countries where onchocerciasis and loiasis are co-endemic.

Batsa Debrah L et al. (2019) Clin Infect Dis "Comparison of repeated doses of ivermectin versus ivermectin plus albendazole for treatment of onchocerciasis - a randomized open-label clinical trial."

Ricchiuto A, Konadu P, Debrah AY, Gruetzmacher B, Weil G, Kazura JW, Klarmann-Schulz U, Dubben B, Hoerauf A, Nadal J, Mubarik Y, King CL, Batsa Debrah L, Osei-Mensah J, Fimmers R, Ayisi-Boateng NK, Fischer K

[Clin Infect Dis, 2019]

BACKGROUND: Improved treatment for onchocerciasis is needed to accelerate onchocerciasis elimination in Africa. Aiming to better exploit registered drugs, this study was undertaken to determine whether annual or semiannual treatment with ivermectin (IVM; 200g/kg) plus albendazole (ALB; 800mg single dose) is superior to IVM alone. METHODS: This trial was performed in Ghana and included 272 microfilaria (MF) -positive participants randomized to 4 treatment arms: 1) IVM annual at 0, 12, and 24 months; 2) IVM semiannual at 0, 6, 12, 18 and 24 months; 3) IVM+ALB annual; 4) IVM+ALB semiannual. Microfiladermia was determined pre-treatment and at 6, 18 and 36 months. The primary outcome was the proportion of fertile and viable female worms in onchocercomata excised at 36 months. RESULTS: Post-treatment nodule histology showed that 15/135 (11.1%), 22/155 (14.2%), 35/154 (22.7%) and 20/125 (16.0%) living female worms had normal embryogenesis in the IVM annual, IVM semiannual, IVM+ALB annual and IVM+ALB semiannual groups respectively (p=0.1229). Proportions of dead worms also did not differ between the 4 groups (p=0.9198). Proportions of patients without MF at 36 months (one year after the last treatment) were 35/56 (63%) after annual IVM, 42/59 (71%) after semiannual IVM, 39/64 (61%) after IVM+ALB annual, and 43/53 (81%) after semiannual IVM+ALB. CONCLUSIONS: The combination treatment with IVM plus ALB was no better than IVM alone for sterilizing, killing of adult worms or achieving sustained MF clearance. However, semiannual treatment was superior to annual treatment for achieving sustained clearance of O. volvulus MF from the skin (p=0.024).