The present review has summarized the status of fish coccidia and has provided an insight into the life cycle, taxonomy, transmission, pathogenesis, prevention, and treatment. Coccidiosis is a disease that is caused by protozoan parasites of the apicomplexan genus Eimeria and is transmitted via ingestion of infective oocysts. It affects many vertebrates and invertebrates causing mortality, poor performance of animals, and reduce productivity. This disease mostly affects the poultry sector, but its different species are also present in fish and cause economic loss. Coccidiosis in fish has been studied extensively, as it is regarded as chronic and its impact is easily overlooked. There are at least 18 genera under 3 families of order Eucoccidiorida that are responsible to cause some form of coccidiosis in different animals including mammals, avians as well as piscine. About 250 species of coccidiosis are known to occur in fish and among them, Eimeria and Goussia spp are the most prevalent ones. Taxonomic classification has been a difficult task and is determined on the basis of morphological features of oocysts. Coccidiosis generally has 3 stages in its lifecycle, with some variation according to species. About 30% of coccidia develops extraintestinal, and most of the fish coccidia are kept under an Eimeria genus. Transmission occurs via direct as well as by indirect method, but direct method id more common and simple. Coccidiosis can cause mild to serve damage and pathogenesis can differ with species. For prevention and control, different anticoccidial drugs are used. However, sanitation is a prime factor to reduce the risk of oocyst's introduction in animals.
Table of Contents
1. Introduction
2. Taxonomy
3. Coccidiosis in fish
4. Life cycle
5. Transmission
6. Pathogenesis
7. Prevention and treatment
8. Conclusion
9. References
Research Objectives and Core Themes
The primary objective of this review is to synthesize the current scientific understanding of coccidiosis in fish, providing a comprehensive analysis of the life cycle, taxonomy, transmission mechanisms, pathogenesis, and management strategies for this parasitic disease in aquaculture environments.
- Taxonomic classification and morphological identification of fish coccidia.
- Mechanisms of direct and indirect transmission of coccidian parasites in fish.
- Pathophysiological impacts and clinical manifestations in infected fish species.
- Prophylactic measures, sanitation strategies, and pharmacological treatments.
- Analysis of the economic implications of coccidiosis on global aquaculture production.
Excerpt from the Book
3. Coccidiosis in fish
The common coccidians causing disease are Eimeria, Isospora, Cryptosporidium, Toxoplasma, Sarcocystis, Besnoitia and Frenkelia. Some of these may need two hosts to complete the life cycle while most of them need single host (Levine & Ivens, 1981). The coccidia are usually host specific, one species which infect one host is generally non-infective to other vertebrate host. Some host harbour more than one parasite, for instance: swine are infected by both Eimeria and Isopora species (Barta, 2001).
All the fish coccodia has been kept under the genus Eimeria, although they do not completely fit with the characters and life cycle pattern of this genus (Dykova & Lom, 1981). Over 200 species of eimeriids have been identified from different species of fish, and their occurrence has been underestimated. Mostly they are not common in fish but have affected certain species severely such as common carp. Piscine coccidia is less species specific than mammalian coccidia and often spread within same genus (Noga, 2010). Coccidiosis in fish is mainly caused by different species of Eimeria, with some reports of Cryptosporidium infections (Paperna, 1996; Landsberg & Paperna, 1986) as well as Goussia spp. (Davies & Ball, 1993; Molnar & Rohde, 1988). Fishes of different species including the elasmobranchs as well as teleosts have been found to be affected by this parasite (Dykova & Lom, 1981) and both wild as well as cultured species are found to be affected (Klinger & Floyd, 2016). Different freshwater fish species such as common carp, channel catfish, Nile tilapia, silver carp, masu salmon, Glossogoobius giuris, and Notopterus notopterus are mostly affected by coccidia.
Summary of Chapters
1. Introduction: Provides an overview of coccidiosis as a globally significant disease in both poultry and fish, highlighting the shift in recent research focus toward aquaculture.
2. Taxonomy: Outlines the historical and current classification of fish coccidia, focusing on the prevalence of the genus Eimeria and the challenges in morphological identification.
3. Coccidiosis in fish: Describes the range of coccidian parasites affecting various fish species and discusses the specific prevalence of Eimeria and Goussia in both cultured and wild fish.
4. Life cycle: Details the three primary stages of the parasite’s life cycle: sporogony, merogony, and gametogony, explaining their biological functions.
5. Transmission: Explains the direct and indirect transmission pathways, including the involvement of intermediate hosts like tubificids and shrimp.
6. Pathogenesis: Analyzes the chronic nature of the disease, clinical symptoms, and the impact of coccidiosis on internal organs such as the intestine, liver, and spleen.
7. Prevention and treatment: Evaluates various anticoccidial drugs and management practices, emphasizing the importance of sanitation and hygiene in aquaculture.
8. Conclusion: Summarizes the key findings and stresses the need for continued taxonomic research and detailed life cycle studies to better manage the disease.
9. References: Provides an extensive list of scientific literature cited throughout the review.
Keywords
Coccidiosis, Fish, Eimeria, Goussia, Aquaculture, Life Cycle, Parasite, Pathogenesis, Transmission, Protozoa, Taxonomy, Prophylaxis, Anticoccidial, Aquaculture Health, Infection.
Frequently Asked Questions
What is the primary scope of this review?
The paper provides a comprehensive overview of coccidiosis in fish, covering the biology, transmission, and management of the disease, primarily focusing on parasites within the genus Eimeria.
What are the central themes discussed in the document?
The central themes include the taxonomy of coccidian parasites, their complex life cycles, transmission methods via direct and intermediate hosts, disease pathogenesis, and potential treatment or prevention strategies.
What is the main research question or goal?
The goal is to synthesize existing knowledge on fish coccidiosis to help identify responsible factors for outbreaks and highlight the need for further research in taxonomy and parasite development.
Which scientific methods are primarily analyzed?
The paper uses a descriptive literature review approach, summarizing diagnostic and experimental studies on fish coccidian infection and treatment efficacy.
What content is included in the main body of the work?
The main body systematically explores taxonomy, life cycle stages (sporogony, merogony, gametogony), transmission methods, clinical pathogenesis, and pharmacological interventions.
Which keywords best describe this research?
Key terms include Coccidiosis, Eimeria, Goussia, Aquaculture, Pathogenesis, and Parasitology.
How does fish coccidiosis differ from coccidiosis in warm-blooded animals?
A significant difference noted is that approximately 30% of fish coccidia develop extra-intestinally, unlike many warm-blooded species where development is primarily gut-focused.
Why is the diagnosis of Eimeria species considered difficult?
Identification is challenging due to the complexity of the species and the limitations of using only morphological characteristics of oocysts, leading to the use of modern rDNA and mitochondrial gene analysis.
What role does sanitation play in preventing outbreaks?
Sanitation is identified as a critical management factor because coccidian oocysts are highly resistant to environmental factors, making ordinary disinfectants ineffective.
- Citar trabajo
- Biplov Shrestha (Autor), 2022, Coccidiosis in fish. Lifecycle of coccidiosis, development, pathogenesis and medications, Múnich, GRIN Verlag, https://www.grin.com/document/1182599
