Relationship between Infection Caused by the Apicomplex Protozoan Nematopsis sp and the Weight of White Shrimp Litopenaeus vannamei in a Cultivation System

There are many types of diseases and etiological agents that affect the health of the cultivated white shrimp Litopenaeus vannamei (viruses, bacteria, fungi, and parasites), with parasitic diseases being of great relevance. From this perspective, the main parasitic diseases in cultured shrimp are given by protozoa, mainly Apicomplexa (Gregarines) and Ciliophora (Epibionts or Ectoparasites). The objective of this research is to establish the mathematical relationship between the infection caused by the apicomplexan protozoan Nematopsis sp and the weight of the white shrimp Litopenaeus vannamei in a cultivation system. This work was carried out on the western coast of the state of Falcón (Venezuela), where several shrimp farms are located. The animals were randomly sampled in the ponds and immediately taken to the laboratory for analysis (presence of the parasite and weight). The results indicate that the physicochemical parameters of the water remained stable during the test. The prevalence of parasitosis was 25% in May/June, 28% in July, 27.64% in August, 35.5% in September and 32% in October. In addition, it was observed that the average weight of shrimp increased over time, being 0.313 in May/June, 3.2765 in July, 7.4831 in August, 11.3776 in September and 12.71 in October. The R value was 0.119 indicating little dependence on the variables, and an R2 of 0.0143 showing that parasitosis only had an effect on the weight of 1.43% of the infected animals.