Experimental Bacterial Co-infection in Nile Tilapia Shows High Pathogenicity from Lake Kariba Isolates
Keywords:
Pathogenicity, Co-infection, Nile tilapia, Small Scale Aquaculture
Abstract
Bacterial diseases are a major constraint to the sustainability of small-scale tilapia aquaculture in Zambia, particularly in cage-culture systems on Lake Kariba, where multiple bacterial pathogens are frequently isolated during disease outbreaks. This study evaluated the pathogenicity of Aeromonas spp., Lactococcus garvieae, Acinetobacter spp., and Klebsiella spp. isolated from diseased Nile tilapia (Oreochromis niloticus) from small-scale farms on Lake Kariba, using controlled mono-infection and co-infection experimental models. Twenty (20) healthy Nile tilapia juveniles were intraperitoneally challenged with individual bacterial isolates, a combined co-infection of all four pathogens, or sterile saline (control). Fish were monitored for clinical signs, cumulative mortality, and gross pathology over 21 days post-infection. Histopathological examination of the liver, kidney, spleen, and skin was conducted, and bacteriological re-isolation was performed to confirm pathogen dissemination. Clinical signs appeared earliest in fish infected with Aeromonas spp. and L. garvieae (1 day post-infection) and later in those infected with Klebsiella spp. and Acinetobacter spp. (2 days post-infection), with severity varying by pathogen. Co-infected fish exhibited the most severe disease, characterized by extensive external lesions, multisystem histopathological damage, rapid systemic dissemination, and 100% cumulative mortality by 7 days post-infection. Mono-infections with L. garvieae and Aeromonas spp. resulted in progressive mortality, reaching 100% by 12 and 16 days post-infection, respectively, whereas Klebsiella spp. and Acinetobacter spp. caused comparatively mild pathology and lower mortality. Bacterial co-infection resulted in markedly higher pathogenicity and faster disease progression than single-pathogen infections. These findings highlight the critical role of co-infections in tilapia disease outbreaks on Lake Kariba and underscore the need for improved biosecurity, strengthened husbandry practices, and development of polyvalent vaccines to support sustainable small-scale aquaculture in Zambia.References
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13. Hasimuna OJ, Maulu S, Nawanzi K, Lundu B, Mphande J, Phiri CJ, Kikamba E, Siankwilimba E, Siavwapa S, Chibesa M. Integrated agriculture-aquaculture as an alternative to improving small-scale fish production in Zambia. Frontiers in Sustainable Food Systems. 2023 May 10;7:1161121. Available from: https://doi.org/10.3389/fsufs.2023.1161121
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15. Oladapo O, Yinusa, M, Bangwe L, Marttin, F, Chimatiro S, Jere N. Zambia - Aquaculture Enterprise Development Project [Internet]. African Development Bank; 2016 [cited 2024 Nov 23]. Available from: https://www.afdb.org/en/documents/document/zambia-aquaculture-enterprise-development-project-93700
16. Siamujompa M, Ndashe K, Zulu FC, Chitala C, Songe MM, Changula K, Moonga L, Kabwali ES, Reichley S, Hang’ombe BM. An investigation of bacterial pathogens associated with diseased Nile tilapia in small-scale cage culture farms on Lake Kariba, Siavonga, Zambia. Fishes. 2023 Sep 8;8(9):452. Available from: https://doi.org/10.3390/fishes8090452
17. Barcellos LG, Nicolaiewsky S, De Souza SG, Lulhier F. The effects of stocking density and social interaction on acute stress response in Nile tilapia Oreochromis niloticus (L.) fingerlings. Aquaculture Research. 1999 Nov;30(11‐12):887-92. Available from: https://doi.org/10.1046/j.1365-2109.1999.00419.x
18. Raman RP, Prakash C, Makesh M, Pawar NA. Environmental stress mediated diseases of fish: an overview. Advances in Fish Research. 2013;5:141-58.
19. Team Data. Skalenniveau. DATAtab; 2022.
20. Aboyadak IM, Ali NG, Goda AM, Aboelgalagel WH, Salam A. Molecular detection of Aeromonas hydrophila as the main cause of outbreak in tilapia farms in Egypt. J Aquac Mar Biol. 2015;2(6):2-5.
21. Laltlanmawia C, Ghosh L, Saha RK, Parhi J, Pal P, Dhar B, Saha H. Isolation, identification and pathogenicity study of emerging multi-drug resistant fish pathogen Acinetobacter pittii from diseased rohu (Labeo rohita) in India. Aquaculture Reports. 2023 Aug 1;31:101629. Available from: https://doi.org/10.1016/j.aqrep.2023.101629
22. Sakala T, Mdegela RH, Hangombe BM. Identifying bacteria associated with diseased Oreochromis niloticus in Lake Kariba, Zambia. Available from: https://smujo.id/bbs/article/view/12220
23. Vaneci-Silva D, Assane IM, de Oliveira Alves L, Gomes FC, Moro EB, Kotzent S, Pitondo-Silva A, Pilarski F. Klebsiella pneumoniae causing mass mortality in juvenile Nile tilapia in Brazil: Isolation, characterization, pathogenicity and phylogenetic relationship with other environmental and pathogenic strains from livestock and human sources. Aquaculture. 2022 Jan 15;546:737376. Available from: https://doi.org/10.1016/j.aquaculture.2021.737376
24. Assane IM, de Sousa EL, Valladão GM, Tamashiro GD, Criscoulo-Urbinati E, Hashimoto DT, Pilarski F. Phenotypic and genotypic characterization of Aeromonas jandaei involved in mass mortalities of cultured Nile tilapia, Oreochromis niloticus (L.) in Brazil. Aquaculture. 2021 Aug 30;541:736848. Available from: https://doi.org/10.1016/j.aquaculture.2021.736848
25. Azzam-Sayuti M, Ina-Salwany MY, Zamri-Saad M, Annas S, Yusof MT, Monir MS, Mohamad A, Muhamad-Sofie MH, Lee JY, Chin YK, Amir-Danial Z. Comparative pathogenicity of Aeromonas spp. in cultured red hybrid tilapia (Oreochromis niloticus× O. mossambicus). Biology. 2021 Nov 17;10(11):1192. Available from: https://doi.org/10.3390/biology10111192
26. Rao S, Pham TH, Poudyal S, Cheng LW, Nazareth SC, Wang PC, Chen SC. First report on genetic characterization, cell‐surface properties and pathogenicity of Lactococcus garvieae, emerging pathogen isolated from cage‐cultured Cobia (Rachycentron canadum). Transboundary and Emerging Diseases. 2022 May;69(3):1197-211. Available from: https://doi.org/10.1111/tbed.14083
27. Abdel‐Latif HM, Khafaga AF. Natural co‐infection of cultured Nile tilapia Oreochromis niloticus with Aeromonas hydrophila and Gyrodactylus cichlidarum experiencing high mortality during summer. Aquaculture Research. 2020 May;51(5):1880-92. Available from: https://doi.org/10.1111/are.14538
28. Nicholson P, Mon-On N, Jaemwimol P, Tattiyapong P, Surachetpong W. Coinfection of tilapia lake virus and Aeromonas hydrophila synergistically increased mortality and worsened the disease severity in tilapia (Oreochromis spp.). Aquaculture. 2020 Apr 15;520:734746. Available from: https://doi.org/10.1016/j.aquaculture.2019.734746
2. Verdegem M, Buschmann AH, Latt UW, Dalsgaard AJ, Lovatelli A. The contribution of aquaculture systems to global aquaculture production. Journal of the World Aquaculture Society. 2023 Apr;54(2):206-50. Available from: https://doi.org/10.1111/jwas.12963
3. Debnath PP, Delamare‐Deboutteville J, Jansen MD, Phiwsaiya K, Dalia A, Hasan MA, Senapin S, Mohan CV, Dong HT, Rodkhum C. Two‐year surveillance of tilapia lake virus (TiLV) reveals its wide circulation in tilapia farms and hatcheries from multiple districts of Bangladesh. Journal of Fish Diseases. 2020 Nov;43(11):1381-9. Available from: https://doi.org/10.1111/jfd.13235
4. Abdelrahman HA, Hemstreet WG, Roy LA, Hanson TR, Beck BH, Kelly AM. Epidemiology and economic impact of disease-related losses on commercial catfish farms: A seven-year case study from Alabama, USA. Aquaculture. 2023 Mar 15;566:739206. Available from: https://doi.org/10.1016/j.aquaculture.2022.739206
5. Dong, H.T., Nguyen, V.V., Le, H.D., Sangsuriya, P., Jitrakorn, S., Saksmerprome, V., Senapin, S. and Rodkhum, C., 2015. Naturally concurrent infections of bacterial and viral pathogens in disease outbreaks in cultured Nile tilapia (Oreochromis niloticus) farms. Aquaculture, 448, pp.427-435. Available from: https://doi.org/10.1016/j.aquaculture.2015.06.027
6. Haenen OL, Dong HT, Hoai TD, Crumlish M, Karunasagar I, Barkham T, Chen SL, Zadoks R, Kiermeier A, Wang B, Gamarro EG. Bacterial diseases of tilapia, their zoonotic potential and risk of antimicrobial resistance. Reviews in Aquaculture. 2023 Feb;15:154-85. Available from: https://doi.org/10.1111/raq.12743
7. Clavijo AM, Conroy G, Conroy DA, Santander J, Aponte F. First report of Edwardsiella tarda from tilapias in Venezuela. Bulletin-European Association of Fish Pathologists. 2002 Jan 1;22(4):280-2.
8. Leal CA, Tavares GC, Figueiredo HC. Outbreaks and genetic diversity of Francisella noatunensis subsp orientalis isolated from farm-raised Nile tilapia (Oreochromis niloticus) in Brazil. Genetics and Molecular Research. 2014 Jul 25;13(3):5704-12. Available from: http://dx.doi.org/10.4238/2014.July.25.26
9. Dong HT, Techatanakitarnan C, Jindakittikul P, Thaiprayoon A, Taengphu S, Charoensapsri W, Khunrae P, Rattanarojpong T, Senapin S. Aeromonas jandaei and Aeromonas veronii caused disease and mortality in Nile tilapia, Oreochromis niloticus (L.). Journal of Fish Diseases. 2017 Oct;40(10):1395-403. Available from: https://doi.org/10.1111/jfd.12617
10. Abu‐Elala NM, Abd‐Elsalam RM, Younis NA. Streptococcosis, Lactococcosis and Enterococcosis are potential threats facing cultured Nile tilapia (Oreochomis niloticus) production. Aquaculture research. 2020 Oct;51(10):4183-95. Available from: https://doi.org/10.1111/are.14760
11. Bwalya P, Simukoko C, Hang'ombe BM, Støre SC, Støre P, Gamil AA, Evensen Ø, Mutoloki S. Characterization of streptococcus-like bacteria from diseased Oreochromis niloticus farmed on Lake Kariba in Zambia. Aquaculture. 2020 Jun 30;523:735185. Available from: https://doi.org/10.1016/j.aquaculture.2020.735185
12. Ciji A, Akhtar MS. Stress management in aquaculture: A review of dietary interventions. Reviews in Aquaculture. 2021 Sep;13(4):2190-247. Available from: https://doi.org/10.1111/raq.12565
13. Hasimuna OJ, Maulu S, Nawanzi K, Lundu B, Mphande J, Phiri CJ, Kikamba E, Siankwilimba E, Siavwapa S, Chibesa M. Integrated agriculture-aquaculture as an alternative to improving small-scale fish production in Zambia. Frontiers in Sustainable Food Systems. 2023 May 10;7:1161121. Available from: https://doi.org/10.3389/fsufs.2023.1161121
14. Zhang L, Maulu S, Hua F, Chama MK, Xu P. Aquaculture in Zambia: the current status, challenges, opportunities and adaptable lessons learnt from China. Fishes. 2023 Dec 29;9(1):14. Available from: https://doi.org/10.3390/fishes9010014
15. Oladapo O, Yinusa, M, Bangwe L, Marttin, F, Chimatiro S, Jere N. Zambia - Aquaculture Enterprise Development Project [Internet]. African Development Bank; 2016 [cited 2024 Nov 23]. Available from: https://www.afdb.org/en/documents/document/zambia-aquaculture-enterprise-development-project-93700
16. Siamujompa M, Ndashe K, Zulu FC, Chitala C, Songe MM, Changula K, Moonga L, Kabwali ES, Reichley S, Hang’ombe BM. An investigation of bacterial pathogens associated with diseased Nile tilapia in small-scale cage culture farms on Lake Kariba, Siavonga, Zambia. Fishes. 2023 Sep 8;8(9):452. Available from: https://doi.org/10.3390/fishes8090452
17. Barcellos LG, Nicolaiewsky S, De Souza SG, Lulhier F. The effects of stocking density and social interaction on acute stress response in Nile tilapia Oreochromis niloticus (L.) fingerlings. Aquaculture Research. 1999 Nov;30(11‐12):887-92. Available from: https://doi.org/10.1046/j.1365-2109.1999.00419.x
18. Raman RP, Prakash C, Makesh M, Pawar NA. Environmental stress mediated diseases of fish: an overview. Advances in Fish Research. 2013;5:141-58.
19. Team Data. Skalenniveau. DATAtab; 2022.
20. Aboyadak IM, Ali NG, Goda AM, Aboelgalagel WH, Salam A. Molecular detection of Aeromonas hydrophila as the main cause of outbreak in tilapia farms in Egypt. J Aquac Mar Biol. 2015;2(6):2-5.
21. Laltlanmawia C, Ghosh L, Saha RK, Parhi J, Pal P, Dhar B, Saha H. Isolation, identification and pathogenicity study of emerging multi-drug resistant fish pathogen Acinetobacter pittii from diseased rohu (Labeo rohita) in India. Aquaculture Reports. 2023 Aug 1;31:101629. Available from: https://doi.org/10.1016/j.aqrep.2023.101629
22. Sakala T, Mdegela RH, Hangombe BM. Identifying bacteria associated with diseased Oreochromis niloticus in Lake Kariba, Zambia. Available from: https://smujo.id/bbs/article/view/12220
23. Vaneci-Silva D, Assane IM, de Oliveira Alves L, Gomes FC, Moro EB, Kotzent S, Pitondo-Silva A, Pilarski F. Klebsiella pneumoniae causing mass mortality in juvenile Nile tilapia in Brazil: Isolation, characterization, pathogenicity and phylogenetic relationship with other environmental and pathogenic strains from livestock and human sources. Aquaculture. 2022 Jan 15;546:737376. Available from: https://doi.org/10.1016/j.aquaculture.2021.737376
24. Assane IM, de Sousa EL, Valladão GM, Tamashiro GD, Criscoulo-Urbinati E, Hashimoto DT, Pilarski F. Phenotypic and genotypic characterization of Aeromonas jandaei involved in mass mortalities of cultured Nile tilapia, Oreochromis niloticus (L.) in Brazil. Aquaculture. 2021 Aug 30;541:736848. Available from: https://doi.org/10.1016/j.aquaculture.2021.736848
25. Azzam-Sayuti M, Ina-Salwany MY, Zamri-Saad M, Annas S, Yusof MT, Monir MS, Mohamad A, Muhamad-Sofie MH, Lee JY, Chin YK, Amir-Danial Z. Comparative pathogenicity of Aeromonas spp. in cultured red hybrid tilapia (Oreochromis niloticus× O. mossambicus). Biology. 2021 Nov 17;10(11):1192. Available from: https://doi.org/10.3390/biology10111192
26. Rao S, Pham TH, Poudyal S, Cheng LW, Nazareth SC, Wang PC, Chen SC. First report on genetic characterization, cell‐surface properties and pathogenicity of Lactococcus garvieae, emerging pathogen isolated from cage‐cultured Cobia (Rachycentron canadum). Transboundary and Emerging Diseases. 2022 May;69(3):1197-211. Available from: https://doi.org/10.1111/tbed.14083
27. Abdel‐Latif HM, Khafaga AF. Natural co‐infection of cultured Nile tilapia Oreochromis niloticus with Aeromonas hydrophila and Gyrodactylus cichlidarum experiencing high mortality during summer. Aquaculture Research. 2020 May;51(5):1880-92. Available from: https://doi.org/10.1111/are.14538
28. Nicholson P, Mon-On N, Jaemwimol P, Tattiyapong P, Surachetpong W. Coinfection of tilapia lake virus and Aeromonas hydrophila synergistically increased mortality and worsened the disease severity in tilapia (Oreochromis spp.). Aquaculture. 2020 Apr 15;520:734746. Available from: https://doi.org/10.1016/j.aquaculture.2019.734746
Published
2026-02-20
How to Cite
1.
Zulu F, Ndashe K, Changula K, Siamujompa M, Chitala C, Songe M, Moonga L, Reichley S, Hang’ombe B. Experimental Bacterial Co-infection in Nile Tilapia Shows High Pathogenicity from Lake Kariba Isolates. Journal of Agricultural and Biomedical Sciences [Internet]. 20Feb.2026 [cited 13Apr.2026];10(2). Available from: https://journals.unza.zm/index.php/JABS/article/view/1497
Section
Veterinary Medicine
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