Diversity, Prevalence, And Composition Of Helminth Parasites In Catla Catla From River Indus, Sindh, Pakistan

Abstract

Pakistan has a rich ichthyological diversity yet little research has been done on the level of freshwater fish parasitology in Pakistan even though the country depends on inland fisheries as a source of food security. Catla catla (Hamilton, 1822) is one of the commercially most important rich major carps in South Asia, and is completely deficient of a former complete helminthological account in the River Indus at Jamshoro, Sindh. This was carried out to document the diversity, prevalence and community structure of the helminth parasites of the Catla catla of this locality and to accomplish this with the help of the standard parasitological methods in a two year study (20182020). The host fish analyzed were 26. Nine (34.617) were infected with helminth. It revealed 6 helminth taxa in three classes (Trematoda 3 species; prevalence 23.07%), Nematoda (2 species; prevalence 7.69%), and Acanthocephala (1 species; prevalence 3.84%). A total of 63 specimens were retrieved in the six taxa. The most abundant (11.54 percent) was the trematode Echinochasmus sp and the most common mean intensity (10.50 specimens per infected host) was the nematode Rhabdochona sp. Thaparotrema pedicellatum, Isoparorchis trisimilitubis, and Echinochasmus sp., Procamallanus (Spirocamallanus) sp., Rhabdochona sp., and Dispirin sp. are all new host or locality records in Pakistan. These findings fill a knowledge gap in the critical regional biodiversity literature, provide the first description of a multi-class helminth community of the catla Catlali in the Indus River drainage and indicate zoonotic risks of Echinochasmus in a food fish with a high degree of harvesting. These findings are put into context of the bigger picture of the South Asian parasitological literature through parallel analysis of similar studies in India and other localities in Pakistan. Expanded surveillance, molecular characterization, and seasonal sampling are proposed as the priorities of research which should be conducted immediately.

Keywords: Catla catla; helminth diversity; prevalence; Trematoda; Nematoda; Acanthocephala; River Indus; Sindh; Pakistan; comparative parasitology; biodiversity gap; zoonosis.