Kenya Fisheries Service

ABSTRACT Parasitic infections threaten the endangered Oreochromis jipe and other ichthyic populations in Lake Jipe, thereby hindering conservation efforts. Initiatives have been made to farm O. jipe as a conservation strategy. To develop effective conservation approaches and ensure the species' survival in its natural habitat and aquaculture systems, it is imperative to understand the diverse parasites in these habitats. Consequently, this cross‐sectional study was conducted to determine parasitic loads in tilapias from selected farms and Lake Jipe. A total of 111 fishes were collected (76 farmed, 35 from the lake), comprising 66 O. jipe , 34 Oreochromis niloticus and 11 hybrids of O. jipe and O. niloticus . The fish were euthanized, necropsied and examined for parasitic infections via visual inspection and light microscopy. Out of 111 fishes examined, 58 (52.3%) were infected with 212 parasites, including 135 (63.7%) and 77 (36.3%) from farm and lake habitats, respectively. The prevalence of parasitic infections in fish from the lake and farm habitats was 68.6% and 44.7%, respectively. The most frequently occurring parasite genera identified were Diplostomum (30.63%), Acanthocephalus (20.7%), Dactylogyrus (9.9%) and Contracaecum (2.7%), with mean intensities of 2.9, 3.7, 1.9 and 1.7, respectively . Contracaecum and Camallanus were exclusively found in fish from Lake Jipe, while Euclinostomum and Gyrodactylus were only observed in farmed fish. O. jipe had the highest prevalence of parasitic infections (59.1%), followed by O. niloticus (44.1%) and hybrids (36.4%) ( p > 0.05). In conclusion, the examined fishes were infected with diverse parasites, which have both public health concerns ( Euclinostomum and Acanthocephalus ) and economic significance ( Dactylogyrus and Gyrodactylus ). Consequently, it is imperative to enhance public awareness and enforce biosecurity measures to mitigate potential health risks and to improve the productivity of the pond culture system and lake ecosystem. These measures will help reduce parasite dissemination and promote sustainable fish production and populations.

Marine fish is a rich source of minerals in the diet of humans, but seasonal variation in fish mineral concentrations is relatively unstudied. We investigated seasonal mineral concentrations among four marine fish species retained by small scale fishers in Msambweni and Vanga fishing villages in Kenya. The fish species were Siganus sutor (rabbitfish) in Msambweni and Decapterus macarellus (mackerel scad), Sphraena forsteri (bigeye barracuda) and Sphyraena obtusata (obtuse barracuda) in Vanga. Mineral concentrations were quantified in 120 fish specimens (60/season) and their mineral supplementation potential evaluated. The concentrations of Potassium (K), Magnesium (Mg), Zinc (Zn), Iron (Fe) and Iodine (I) were determined using Inductively Coupled Plasma Optical Emission Spectrometry. K, Mg, Zn and I levels in fish samples varied between seasons with higher concentrations during the wet and cool southeast monsoon (SEM) season (April to October). However, Fe concentration was significantly higher during the dry and warm northeast monsoon (NEM) (November to March). S. fosteri recorded the highest concentrations of Mg (72.29 mg/100g in SEM) and Fe (3.63 mg/100g in NEM). S. sutor was the richest source of K (410.21 mg/100g in SEM). These two species also recorded the highest concentration of I (57.6 μg/100g in SEM) while D. macarellus had the highest Zn concentration (5.84 mg/100g in SEM). Mineral concentrations were dependent on fish species as well as season, influencing the mineral intake in Msambweni and Vanga villages.

The antimicrobial resistance catastrophe is a growing global health threat and predicted to be worse in developing countries. Phages for Global Health (PGH) is training scientists in these regions to isolate relevant therapeutic phages for pathogenic bacteria within their locality, and thus contributing to making phage technology universally available. During the inaugural PGH workshop in East Africa, samples from Ugandan municipal sewage facilities were collected and two novel Escherichia coli lytic phages were isolated and characterized. The phages, UP19 (capsid diameter ∼100 nm, contractile tail ∼120/20 nm) and UP30 (capsid diameter ∼70 nm, noncontractile tail of ∼170/20 nm), lysed ∼82% and ∼36% of the 11 clinical isolates examined, respectively. The genomes of UP19 (171.402 kb, 282 CDS) and UP30 (49.834 kb, 75 CDS) closely match the genera Dhakavirus and Tunavirus, respectively. The phages isolated have therapeutic potential for further development against E. coli infections.

An 8-week study was conducted to evaluate the effects of different feeding patterns with dietary Clostridium butyricum supplementation on growth performance, antioxidant and non-specific immune responses in freshwater prawn, Macrobrachium rosenbergii (0.39 ± 0.001 g). There were four feeding methodologies: feeding basal diet continuously (P1); feeding diet with 500 mg/kg C. butyricum continuously (P2); feeding diet with 500 mg/kg C. butyricum 5 days after 2 days of basal diet (P3) and feeding diet with 500 mg/kg C. butyricum 2 days after 5 days of basal diet (P4). The results revealed that prawns in P3 had the highest weight gain rate (WGR) and lowest feed conversion ratio (FCR) than the other groups. Haemolymph total protein levels and superoxide dismutase activity increased significantly in P2, P3 and P4 groups, while malondialdehyde content and anti-superoxide anion levels decreased significantly compared to control. The mRNA expression of intestinal dorsal and Toll in P2 and P3 groups decreased significantly compared to control. Prawns in P3 exhibited improved growth performance, increased antioxidant capacity and enhanced immune function. We concluded that feeding diet with 500 mg/kg C. butyricum for 5 days after 2 days of basal diet was recommended for M. rosenbergii.