Riordan K
Ann Trop Med Parasitol. 1977 Mar;71(1):11-20. doi: 10.1080/00034983.1977.11687156.
One thousand, nine hundred and ninety-seven male and 1988 female Glossina morsitans submorsitans were dissected at Ogbomosho, on a trade cattle route in south-western Nigeria, from June 1970 to August 1973. Of male flies, 1307 (65-45%) were infected by Trypanosoma vivax trypanosomes, 66 (3-31%) by the subgenus Nannomonas (congolense group) and three (0.15%) by the subgenus Trypanozoon (brucei group). Of flies, 1236 (62-17%) had T. vivax infections, 80 (4-02%) had infections of the subgenus Nannomonas and two (0.10%) had infections of the subgenus Trypanozoon, The great majority of T. vivax infections were mature, while a high proportion (10% in males and 22% in females) of infections of the subgenus Nannomonas were immature. No infection with the subgenus Trypanozoon was found after October 1971. Overall infection rates, for male and female flies respectively, rose from 77% and 80% in June 1970 to peak values of 91% ad 90% in April and June 1971 and thereafter declined to lowest values of 37% and 43% in 1973. The incidence of T. vivax infections was the major component of the rises and falls in overall infection rate. During the period of peak infection rates (April-June 1971), all female flies over about 40 days old were infected. It was assumed that all these had T. vivax infections; some also had subgenus Nannomonas infections and one also had an infection of the subgenus Trypanozoon. Of 72 specimens of G. tachinoides dissected at Ogbomosho from June 1970 to August 1972, 20 (27-8%) were infected by trypanosomes, 19 with T. vivax and one with immature subgenus Nannomonas. In this species, also, infection rate was related to the age of the fly. Of 43 specimens of G. m. submorsitans dissected at Ilorin, north of Ogbomosho on the same cattle route, in February 1975, seven (16-3%) had T. vivax infections. One of two specimens of G. tachinoides dissected here at the same time had an immature infection of the subgenus Nannomonas. In G. m. submorsitans, variations in age structure of the population did not account for the temporal fluctuations in infection rates. It appeared that since 1970 events further north, especially tsetse eradication and the natural decline of tsetse populations (due probably to drought) reduced the trypanosomiasis risk to cattle proceeding southwards. The declining infection rates at Ogbomosho, after 1971, reflected this.
1970年6月至1973年8月期间，在尼日利亚西南部一条贸易牛路线上的奥格博莫索，解剖了1997只雄性和1988只雌性莫氏舌蝇。在雄性苍蝇中，1307只（65.45%）感染了活跃锥虫，66只（3.31%）感染了南诺莫纳属（刚果锥虫组），3只（0.15%）感染了锥虫亚属（布氏锥虫组）。在雌性苍蝇中，1236只（62.17%）感染了活跃锥虫，80只（4.02%）感染了南诺莫纳属，2只（0.10%）感染了锥虫亚属。活跃锥虫的感染大多是成熟的，而南诺莫纳属的感染有很大比例（雄性为10%，雌性为22%）是不成熟的。1971年10月以后未发现锥虫亚属的感染。雄性和雌性苍蝇的总体感染率分别从1970年6月的77%和80%上升到1971年4月和6月的峰值91%和90%，此后下降到1973年的最低值37%和43%。活跃锥虫感染的发生率是总体感染率上升和下降的主要组成部分。在感染率高峰期（1971年4月至6月），所有约40天以上的雌性苍蝇都被感染。假定所有这些苍蝇都感染了活跃锥虫；有些还感染了南诺莫纳属，还有一只感染了锥虫亚属。1970年6月至1972年8月在奥格博莫索解剖的72只嗜人瘤蝇标本中，20只（27.8%）感染了锥虫，19只感染活跃锥虫，1只感染不成熟的南诺莫纳属。在这个物种中，感染率也与苍蝇的年龄有关。1975年2月，在奥格博莫索以北同一条牛路线上的伊洛林解剖的43只莫氏舌蝇标本中，7只（16.3%）感染了活跃锥虫。同时在此解剖的2只嗜人瘤蝇标本中有1只感染了不成熟的南诺莫纳属。在莫氏舌蝇中，种群年龄结构的变化不能解释感染率的时间波动。似乎自1970年以来，更北部的事件，特别是采采蝇的根除和采采蝇种群的自然减少（可能由于干旱）降低了向南行进的牛感染锥虫病的风险。1971年以后奥格博莫索感染率的下降反映了这一点。
