Parasitic Contamination Of Fishes

CHAPTER ONE
INTRODUCTION
BACKGROUND OF THE STUDY
Fish is very important to human populace in trade and economy; it is of importance in the diet of different countries, especially in the tropics and subtropics where malnutrition is a major problem (Aluneet a.,2016). As the human population inevitably increases, the demand for fish as source of protein also grows. In recent times, there has been tremendous increase in the development of fish farming and culture attributed to the increased need for affordable animal protein, especially in the tropics (Davies et al., 2016). Therefore, catfishes of the family Clariidae are increasingly being used for freshwater aquaculture in Africa, owing to several favourable cultural characteristics.

A parasite is an organism that lives in or on another larger organism of a different species (the host), upon which it depends for food. Although the parasite benefits from the association, the host is harmed. Depending on the species, the host/parasite relationship may be temporary or permanent. Bacteria and viruses are classified as parasites in some branches of biology. Fishes are subject to a wide variety of diseases including bacteria, fungi and miscellaneous parasites. Broken head disease with a symptom of skeletal deformities (lardosis and scoliosis) makes fish suddenly stop feeding, becomes lethargic and dies with swollen weak tissues on both sides of the head, usually observed on fish >10 cm, dead fish exhibit thick and curved skulls. Parasitic infection and diseases are some of the factors hindering high productivity in fish farming (Kayis et al. 2019). The majority of the fish parasites which cause disease in fish include protozoan parasites. Typically, these parasites are present in large numbers either on the surface of the fish, within the gills, or both. When they are present in the gills, they cause problems with respiration, and death will commonly occur when additional stressors are present in the aquatic environment. Protozoan parasites on the skin, fins or scales only (i.e., not affecting the gills) usually do not result in death unless they are accompanied by a secondary bacterial infection. According to Klinger and Francis (2010), protozoa are a vast assemblage of eukaryotic organisms, and most of the commonly encountered fish parasites are protozoa, which with practice are the easiest to identify and easiest to control. In general, protozoa are one of the major fish parasites that have been long neglected because of the inherent difficulty in studying compared to other larger parasites. Among protozoa, ecto and endo parasitic protozoa occupy a very important sector as one of the hazardous threats to fish health.

These parasites attack the fish, causing massive destruction of skin and gill epithelium. Even moderate infection of these organisms on small fish may prove a fatal disease, since the infection may cause the fish to stop feeding.

Parasites are capable of causing harm to the fish host notwithstanding the sp., either through injury to the tissues or organs in the process of burrowing or consuming food or the removal of digested food in the gut of the fish as well as the secretion of proteolytic enzymes. Parasites generally don’t kill their hosts (it is a dumb parasite that kills its free lunch), but some can severely stress fish populations to the point of becoming biological and economical concerns. Parasites have a stake in the survival of their host. Sometimes, when parasites are numerous or the fish is stressed from another cause, the fish will die. Parasites can weaken a fish by destroying tissue, removing blood and cellular fluids, diverting part of its nutrient supply and allowing secondary infections to develop.

Fish parasites result in economic losses not only mortality, but also from treatment expenses, growth reduction during and after outbreak of disease and this militates against expansion of aquaculture. Protozoan parasites cause serious losses in fishponds and wild in Nigeria, and their lesions render the fish unmarketable. Fish carrying protozoa parasites are capable of passing on the infective disease to man after its consumption. Protozoa are common tropical freshwater fish parasites that affect public health and cause losses to fishes, hence its choice for this study. One of the scientific importance of identifying a fish properly is to tell to some extent the health condition of the fish, and certain parasitic infections present with some symptoms that bear on the external treatment of the fish (Schmitt and Dethloff, 2010).

Some fish parasites would develop in humans if the fish is eaten raw, but none would be harmful if the fish is thoroughly cooked. All reports of people being infested with fish parasites were because of ingestion of raw fish or insufficiently cooked fish (hubs et al., 2011). Most fish, especially in the wild population, are likely to be infested with parasites, but in the great majority of cases, no significant harm to the host may be encountered or identified; thus, there are only few reports of parasites causing mortality or serious damage to the fish populations, but this may be largely because such effects go unnoticed (Robert, 2011).

The study revealed that bacterial infections as well as parasitic ectoprotozoans, cestodes, trematodes, nematodes, polychaetes and crustaceans are the most prevalent problems in African freshwater, the wild, brackish water and marine aquaculture. There have been isolated reports of viral diseases (infectious pancreatic necrosis (IPN), lymphocystis and spring viraema). Bacterial diseases are restricted to common agents such as Aeromonas, myxobacteria and some other ubiquitous facultative bacteria. Saprolegnia is the most common problematic fungus affecting fish under culture conditions. Currently, the most widely used chemicals for prophylaxis and treatment include wide spectrum antibiotic formulations, malachite green, methylene blue, formalin/ethanol, copper sulphate, salt and several organophosphates. From an aquaculture perspective, it was noteworthy that disease and parasite infestations have been poorly studied in Africa. It is hypothesized that this is mainly due to the low-level intensity of aquaculture in the region. At present the paucity of research on fish diseases in Africa is not seen as a factor that will negatively impact on aquaculture development and in the wild, and as such is not a target research area. Africa is considered to be the sleeping giant of aquaculture, and at the present moment it is relatively disease free. It is vitally important that African countries take steps to safeguard this status. One method of accomplishing this is to restrict the importation of fishes into Africa. The importation of ornamental aquarium fish as well as hybrid and genetically improved fish strains poses the greatest threats. Early detection of fish parasites prevents more serious outbreak which may lead to fish stress and death if not treated on time. A situation that fish farmers dread. Due to economic and biological losses associated with parasites infestation, it becomes imperative to study the level of parasitism in the lakes/water bodies in which fishes live. As yet, no epidemics of endoparasites have been reported in Nigeria, it is likely that as fish culture becomes more intensive and widespread, fish parasites are likely to become a serious economic and health issues (Ikomi, 2011). As a result of this, there is need for the study of fish parasites with the aim of controlling them.

1.2 PROBLEM STATEMENT
Waterborne parasitic diseases form one of common and important public health and economic problems in low- and middle-income countries, though little is known on the burden and patterns of these diseases in most regions. In addition to public health impact, waterborne diseases can have a significant impact on the economy of endemic countries and globally. While there are global concerns regarding waterborne diseases, especially in resource poor countries such as those of Africa, information on the burden and distribution of these diseases is limited. Parasites are common in most ecological systems, and all free living organisms can be potential hosts to parasites (Madanire-Moyo et al., 2010). Parasites play an important role in the ecology of aquatic ecosystems. They can cause harm to the host by tissue damage and can also make the host more susceptible to secondary infection, by weakening host immunity and subsequent economic losses resulting from fish mortality (Peek, 2012). The possibility of parasites harboring bacteria or viruses and being able to transmit them to the host organism has been reported (Lasee, 2015). There is a public health concern on some parasitic diseases which may be transmitted from fish to man through fish consumption, thereby posing health hazards to raw fish consumers(Ibiwoye, 2014). Endoparasitic diseases affect the normal health conditions and cause reduction of growth, abnormal metabolic activities and even death of affected fish, and when these affected fish is consumed raw it can imposed different diseases to the consumer. This called for the study of parasitic contamination of fishes purchased from river fishing community.

1.3 AIM AND OBJECTIVE OF THE STUDY
The aim of this study was to investigate the prevalence and abundance of parasitic contamination of fishes purchased from wudil river fishing Community, Wudil Kano State, Nigeria.

The objectives are:

• To present systematic scoping review summarizes prevalence and patterns of waterborne parasitic diseases of in Wudil River fishing community and global efforts to control the diseases.
• To detect the presence of parasites in fishes sold in that area.
• To study and become familiar with waterborne parasitic diseases
• To recommend appropriate measures to safeguard the possible health implications to fish consumers.

1.4 SIGNIFICANCE OF THE STUDY
This study will make the reader to understand the parasiticinfectionseffect on river fishes. This is of great significance because in manycountries, contaminated fishes are sold in markets.

This study will also throw light on the parasitic contamination occurred and how they are been contacted.

The study will also expose the reader on the need for continuous research onriver fish quality and sanitation.

1.4 SCOPE OF THE STUDY
The scope of this study covers examining the prevalence of parasites in some fresh water fishes from Wudil river, reveals that species get infected based on the content and the level of toxicity of the water they live in, once the fish is infected with one diseases or the other, they show various types of symptoms depending on the type of disease.

1.7 RESEARCH METHODOLOGY
In thecourse of carrying this study, numerous sources were used which most of them are by visiting libraries, consulting journal and news papers and online research which Google was the major source that was used.

1.8 PROJECT ORGANIZATION
The work is organized as follows: chapter one discuses the introductory part of the work,   chapter two presents the literature review of the study,  chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.