{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,9,23]],"date-time":"2025-09-23T14:11:23Z","timestamp":1758636683243},"reference-count":22,"publisher":"Cambridge University Press (CUP)","issue":"2","license":[{"start":{"date-parts":[[2009,4,6]],"date-time":"2009-04-06T00:00:00Z","timestamp":1238976000000},"content-version":"unspecified","delay-in-days":6214,"URL":"https:\/\/www.cambridge.org\/core\/terms"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Parasitology"],"published-print":{"date-parts":[[1992,4]]},"abstract":"<jats:title>SUMMARY<\/jats:title><jats:p><jats:italic>Onchocerca ochengi<\/jats:italic> is a common parasite of cattle in savanna areas of West Africa and its adult stages inhabit intradermal nodules. We have exploited the accessibility of the macrofilariae to examine quantitative and qualitative differences in both the macro- and microfilariae (mff) in relation to age in naturally infected cattle. Autochthonous cattle at a site on the Adamawa plateau, North Cameroon, situated near a perennial <jats:italic>Simulium damnosum<\/jats:italic> s.l. breeding site, were examined in three age groups (1\u00b75\u20132\u00b75, <jats:italic>n<\/jats:italic> = 34; 3\u20135, <jats:italic>n<\/jats:italic> = 39 and \u2265 8 years old, <jats:italic>n<\/jats:italic> = 21). Skin mff densities were assessed from ventral skin biopsies, total body counts of nodules were done by palpation and 1\u20134 nodules were excised from positive animals, collagenase digested and the numbers and condition of macrofilariae determined. Embryogenesis profiles (embryograms) were done on a representative number of female worms in each age group. The overall prevalence of infection in the study population was 71% for mff and 85% for nodules. Nodule prevalence increased significantly from the 1\u00b75\u20132\u00b75 to 3\u20135 years old groups, but no other inter-age prevalences were significantly different. While the mean number of nodules per animal increased with age, geometric means (gm) 3\u00b77, 15\u00b75 and 23\u00b71, the skin mff density maximized in the middle age group and decreased significantly in the old animals (gm 15\u00b78, 44\u00b77 and 11\u00b74 mff\/g, difference between latter two parameters significant, <jats:italic>P<\/jats:italic> &lt; 0\u00b705). Moreover, there was a significant correlation (<jats:italic>P<\/jats:italic> &lt; 0\u00b701) between individual nodule counts and skin mff densities in the mid-aged group but not in the oldest group. Examination of nodules showed that nodule counts equated to numbers of female worms, since almost all of 133 nodules examined contained only 1 live female worm. Although the proportion of old female (and male) worms increased with the age groups \u2013 2 (0), 30 (28) and 54 (32)% \u2013 the proportion of gravid females (52\u00b78, 48\u00b78 and 58\u00b70%) and the mean number of viable embryos in these females (82\u00b75 \u00d7 10<jats:sup>3<\/jats:sup>, 76\u00b70 \u00d7 10<jats:sup>3<\/jats:sup> and 102\u00b71 \u00d7 10<jats:sup>3<\/jats:sup>) did not change with age. Thus, due to the higher nodule counts, a calculated productivity index reflecting the potential mff production per animal was 8 times higher in the \u2265 8-year-old animals than in the youngest and 3 times higher than in the middle group, which sharply contrasts with the decline in skin mff density. Although further research is required, these findings may indicate acquired immunity directed against microfilariae. They demonstrate the potential of <jats:italic>O. ochengi<\/jats:italic> infections in cattle to investigate a number of aspects of the host\u2013parasite relationship which may have relevance to human onchocerciasis.<\/jats:p>","DOI":"10.1017\/s0031182000061680","type":"journal-article","created":{"date-parts":[[2009,6,5]],"date-time":"2009-06-05T14:25:25Z","timestamp":1244211925000},"page":"247-252","source":"Crossref","is-referenced-by-count":25,"title":["Age-related differences in parasitosis may indicate acquired immunity against microfilariae in cattle naturally infected with <i>Onchocerca ochengi<\/i>"],"prefix":"10.1017","volume":"104","author":[{"given":"A. J.","family":"Trees","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"G.","family":"Wahl","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"S.","family":"Kl\u00e4ger","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"A.","family":"Renz","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"56","published-online":{"date-parts":[[2009,4,6]]},"reference":[{"key":"S0031182000061680_ref014","first-page":"423","article-title":"The collagenase technique: how to isolate and examine adult Onchocerca volvulus for the evaluation of drug effects","volume":"39","author":"Schulz-Key","year":"1988","journal-title":"Tropical Medicine and Parasitology"},{"key":"S0031182000061680_ref019","doi-asserted-by":"publisher","DOI":"10.1017\/S0031182000055268"},{"key":"S0031182000061680_ref017","first-page":"34","article-title":"Investigations on female Onchocerca volvulus for the evaluation of drug trials","volume":"31","author":"Schulz-Key","year":"1980","journal-title":"Tropenmedizin und Parasitologie"},{"key":"S0031182000061680_ref021","doi-asserted-by":"publisher","DOI":"10.1080\/00034983.1989.11812393"},{"key":"S0031182000061680_ref010","doi-asserted-by":"publisher","DOI":"10.1016\/0035-9203(83)90307-3"},{"key":"S0031182000061680_ref006","first-page":"469","article-title":"An evaluation of the bovine-Onchocerca gibsoni, Onchocerca gutturosa model as a tertiary screen for drugs against Onchocerca volvulus in man","volume":"30","author":"Copeman","year":"1979","journal-title":"Tropenmedizin und Parasitologie"},{"key":"S0031182000061680_ref005","doi-asserted-by":"publisher","DOI":"10.4269\/ajtmh.1983.32.123"},{"key":"S0031182000061680_ref004","first-page":"276","article-title":"Further studies on the resistance to Onchocerca microfilariae in CBA mice","volume":"37","author":"Carlow","year":"1986","journal-title":"Tropical Medicine and Parasitology"},{"key":"S0031182000061680_ref002","first-page":"349","volume-title":"Parasites \u2013 Their World and Ours, Proceedings of the Fifth International Congress of Parasitology, 7\u201314 August Toronto, 1982. Molecular and Biochemical Parasitology","author":"Bianco","year":"1982"},{"key":"S0031182000061680_ref003","doi-asserted-by":"publisher","DOI":"10.1111\/j.1365-3024.1988.tb00223.x"},{"key":"S0031182000061680_ref001","doi-asserted-by":"publisher","DOI":"10.1080\/00034983.1984.11811873"},{"key":"S0031182000061680_ref007","first-page":"46","article-title":"The prevalence of Onchocerca spp. in cattle in northern Togo in 1979","volume":"37","author":"Denke","year":"1986","journal-title":"Tropical Medicine and Parasitology"},{"key":"S0031182000061680_ref022","doi-asserted-by":"publisher","DOI":"10.1080\/00034983.1991.11812569"},{"key":"S0031182000061680_ref012","first-page":"157","article-title":"The development of Onchocerca ochengi (Nematoda: Filaroidea) to the infective stage in Simulium damnosum s.l. with a note on the histochemical staining of the parasite","volume":"30","author":"Omar","year":"1979","journal-title":"Tropenmedizin und Parasitologie"},{"key":"S0031182000061680_ref016","first-page":"428","article-title":"Isolation of living adult Onchocerca volvulus from nodules","volume":"28","author":"Schulz-Key","year":"1977","journal-title":"Tropenmedizin und Parasitologie"},{"key":"S0031182000061680_ref008","first-page":"445","article-title":"Population dynamics of Onchocerca volvulus after 7 to 8 years of vector control in West Africa","volume":"44","author":"Karam","year":"1987","journal-title":"Acta Tropica"},{"key":"S0031182000061680_ref011","doi-asserted-by":"publisher","DOI":"10.1016\/0035-9203(92)90443-G"},{"key":"S0031182000061680_ref018","doi-asserted-by":"publisher","DOI":"10.1017\/S0022149X00034684"},{"key":"S0031182000061680_ref013","doi-asserted-by":"publisher","DOI":"10.1016\/0035-9203(84)90309-2"},{"key":"S0031182000061680_ref009","doi-asserted-by":"publisher","DOI":"10.4269\/ajtmh.1985.34.907"},{"key":"S0031182000061680_ref020","first-page":"202","article-title":"Immunity to Onchocerca lienalis microfilariae in mice. 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Resistance induced by the homologous parasite","volume":"35","author":"Townson","year":"1984","journal-title":"Tropenmedizin und Parasitologie"},{"key":"S0031182000061680_ref015","first-page":"27","article-title":"Observations on the reproductive biology of Onchocerca volvulus","volume":"59","author":"Schulz-Key","year":"1990","journal-title":"Acta Leidensia"}],"container-title":["Parasitology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.cambridge.org\/core\/services\/aop-cambridge-core\/content\/view\/S0031182000061680","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,5,16]],"date-time":"2019-05-16T22:03:17Z","timestamp":1558044197000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.cambridge.org\/core\/product\/identifier\/S0031182000061680\/type\/journal_article"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1992,4]]},"references-count":22,"journal-issue":{"issue":"2","published-print":{"date-parts":[[1992,4]]}},"alternative-id":["S0031182000061680"],"URL":"https:\/\/doi.org\/10.1017\/s0031182000061680","relation":{},"ISSN":["0031-1820","1469-8161"],"issn-type":[{"value":"0031-1820","type":"print"},{"value":"1469-8161","type":"electronic"}],"subject":[],"published":{"date-parts":[[1992,4]]}}}