In recent years, intensification of aquaculture production in the Lake Victoria Crescent, Uganda has resulted in increased parasitic disease occurrences. However, despite the efforts made, the parasite burden has continued to cause fish mortality. Notably, the different production systems provide different habitats and environmental conditions for the parasites and understanding of the parasite infestation dynamics in these culture systems may provide better sanitary and farm management strategies for the parasite burden. Therefore, the study compared the parasite prevalence and mean intensity of pond and cage cultured Nile tilapia and also identified statistical associations between parasitic infestation and farm management practices. Across the Crescent, a high infestation rate of 65% (418/640) with Trichodina spp. being most prevalent and abundant, and a 16 parasite taxa; 6 protozoa, 2 monogenea, 2 digenea, 1 crustacea, 3 cestode, and 1 acanthocephala was obtained. Furthermore, nearly all parasites were recovered in 3 fish organs; gills harboring 50% (8/16), intestines with 31% (5/16) and skin with 25% (4/16) of the parasite genera. Fish from Pond grow-out and Hatchery farming system harboured ≥ 11 parasite genera while ≤ 5 parasite genera were found in Cage grow-out (lake) and Cage grow-out (reservoir) farms namely; Pond grow-out: 5 protozoa, 1 monogenea, 2 digenea, 1 crustacea, 2 cestode; Cage grow-out (lake): 2 protozoa, 1 monogenea, 2 digenea; Cage grow-out (reservoir): 2 protozoa, 1 monogenea, and Hatchery: 3 protozoa, 2 monogenea, 2 digenea, 1 crustacea, 2 cestode, and 1 acanthocephala. Definitely, Trichodina spp. and Dactylogyrus spp. were recorded in all culture systems but with Trichodina spp. having the highest prevalence and mean intensity in Cage grow-out (reservoir). After classification of infestation, the comparative assessment between Pond grow-out and Cage grow-out (lake) farming systems revealed that 66 % (12/18) of Pond grow-out farms had normal/ frequent infestation and with one farm having very severe/ severe infestation whereas, 33 % (3/9) of Cage grow-out (lake) had gradual/ rare infestation yet with no farm having very severe/ severe infestation. The Fisher's exact test revealed that in Pond grow-out, the relatively high infestation was significantly associated with all the farm management practices: fish seed source, stocking density, feeding and nutrition, disinfection, control of intermediate hosts, and control of wild fish entry, while in Cage grow-out (lake), the relatively low infestation was only significantly associated with stocking density, feeding and nutrition, and control of wild fish entry. Therefore, the findings from the study suggest that proper farm management practices will reduce on the parasite proliferation in the Crescent.

A study was conducted to determine the estimated parasitic infestation and associated risk factors (Water quality, Farm management practices and External factors such as Intermediate hosts and Wild fish entry) of farmed Nile tilapia in Pond grow-out, Cage grow-out (lake), Cage grow-out (reservoir) farms and Hatcheries in the Lake Victoria Crescent, Uganda. Sixteen parasite genera and 65% (418/640) infestation rate were obtained. However, Pond grow-out farms and Hatcheries did not only constitute 81% and 63% of the parasite genera, but also had the highest mean number of parasite genera per farm of 1 to 7 and 4 to 8 respectively. Cage grow-out (reservoir) farms and Hatcheries had the highest mean prevalence of >0.7. Water quality parameters, farm management practices and external factors varied across the 4 farming systems, with Cage grow-out farms (lake) with the best water quality parameters, farm management practices and control over intermediate hosts and wild fish entry. Using Spatial Areal Unit Modelling with Conditional Autoregressive Priors, out of 16 risk factors, only Intermediate hosts had a significant effect on estimated parasitic infestation. Estimated parasitic infestation of 0.28 (low) or 0.55 (high) prevalence was obtained. All Cage grow-out (reservoir) farms and Hatcheries, and 78% (14/18) of Pond grow-out farms had high estimated parasitic infestation despite their locations, while 75% (3/4) of Pond grow-out farms that had low estimated parasitic infestation were located in Masaka (an area with many minor and less polluted rivers). Fifty-six percent (5/9) of Cage grow-out (lake) had low estimated parasitic infestation and were located in the Southern part of Wakiso, Southern part of Mukono and Southern part of Jinja but far from the Napoleon Gulf. The Cage grow-out farms with high estimated parasitic infestation were found in the Southeastern part of Buikwe (an area with sugar cane plantations and factories) and Southern part of Jinja in the polluted Napoleon Gulf. Therefore, the type of farming system and its location (spatial component) need to be given at-most importance when coming up with management and sanitary control strategies to encounter parasite infestation.