A Survey of Infectious Diseases and Parasites of Penaeid Shrimp from the Gulf of Mexico

Abstract

A histopathological survey of wild and cultured shrimp from the Gulf of Mexico was carried out to determine the prevalence and severity of infectious diseases and parasites, affecting four species of penaeid shrimp (Litopenaeus setiferus, Farfantepenaeus aztecus, F. duorarum, and L. vannamei). Around 60 shrimp were obtained from each of 10 sampling stations during different months in 1999 and 2000. One station was a shrimp culture farm from Tamaulipas State, and nine were wild stations from Tamaulipas (five), Veracruz (one), and Campeche (three) States. Thirty shrimp from each station were used for histological analysis. The remaining shrimp were frozen and kept at −20 C to carry out PCR techniques to determine the presence of white spot syndrome virus (WSSV). Some in situ hybridization analyses were applied to ascertain cases of WSS viral disease. Fresh analysis was carried out in shrimp from only one station for parasite identification. The histopathological survey performed on 688 shrimp showed no evidence of viral diseases. Two shrimp from one station were histologically diagnosed as having presumptive WSSV. Tissues from the same shrimp were processed for in situ hybridization and another 20 samples from the same station were processed to run PCR techniques. In each case, the results were negative. The same PCR procedure was applied to the rest of the frozen samples and none of them showed the presence of the WSSV. No important bacterial infections were observed in any of the wild or cultured shrimp analyzed. Fresh analysis demonstrated the presence of the cestode Prochristianella hispida and the gregarines Cephalolobus penaeus and Nematopsis penaeus. Histological analysis showed that the abundance of P. hispida varied from 7 to 90%, and G1 to G4 grades of severity were observed, with G1 being the most common. Gregarines were commonly observed in the histological slides, with a prevalence varying from 3 to 56% and G1 severity in most cases. Haplosporidan infection was observed in one sample of F. duorarum, which is the first report of this parasite in this host. Two invasive epibionts, the filamentous bacteria Leucothrix sp. and the ciliate Ascophrys sp., were found in four sampled stations. The study showed that in ten stations sampled from 1999 to 2000 in the Gulf of Mexico, shrimp populations had no serious infectious diseases.

Survey of protozoan, helminth and viral infections in shrimp Litopenaeus setiferus and prawn ­Macrobrachium acanthurus native to the Jamapa River region, Mexico

“…About 80% of shrimp Litopenaeus setiferus that we examined exhibited low-grade cell necrosis and tissue melanization in gills similar to that reported by Chávez-Sánchez et al (2002), who attributed such histolopathology to the ciliate Ascophrys. Although the degree of infection was low (score = 1), this could be sufficient for L. setiferus to mount a defence response to the chitinase produced by ciliates of the subclass Apostomatia -an enzyme which erodes the Average intensity (±SD) Northwind 14.5 ± 4.1 0 0 2.7 ± 1.0 11.7 ± 3.8 Dry 5.4 ± 3.1 9.2 ± 2.9 0 8.1 ± 3.3 9.3 ± 3.5 Rainy 6.8 ± 2.9 12.6 ± 7.2 4.1 ± 1.8 8.1 ± 2.6 15.7 ± 3. host cuticle (Bradbury & Goyal 1976) and stimulates hemocytic infiltration and inflammation at the site of attachment as well as in the surrounding tissue (Couch 1983, Edgerton et al 2002.…”

“…For example, Prochristia nella sp. was seen in only 1 of the 91 shrimp examined, compared to a prevalence of 33 to 94% reported pre viously (Aldrich 1965, Chávez-Sánchez et al 2002, Vidal-Martínez et al 2002. Ascophrys was also more prevalent in the L. setiferus that we examined (49%) compared with the figure reported previously (3%) (Chávez-Sánchez et al 2002).…”

“…was seen in only 1 of the 91 shrimp examined, compared to a prevalence of 33 to 94% reported pre viously (Aldrich 1965, Chávez-Sánchez et al 2002, Vidal-Martínez et al 2002. Ascophrys was also more prevalent in the L. setiferus that we examined (49%) compared with the figure reported previously (3%) (Chávez-Sánchez et al 2002). These differences could be due to many factors, including sample size and environmental conditions at sampling locations near the mouth of the Jamapa River; for instance, shrimp at these sampling locations had most likely migrated recently from wetland brackish water (18 ppt) to more saline water environments (Jiménez-Badillo 2006).…”

“…The prevalence and severity of infection were quantified according to Bush et al (1997). The criteria for pathology, proposed by Lightner (1996 p. 304) and Chávez-Sánchez et al (2002), were based on an ascending scale of severity ranging from 1 to 4.…”

“…The health status of cultured and wild shrimp has been reported from some areas of Mexico (Chávez-Sánchez et al 2002, Vidal Martínez et al 2002, López-Téllez et al 2009), but little is known about the health status of palaemonid prawns. For instance, white spot syndrome virus (WSSV) and infectious hypodermal and hematopoietic necrosis virus (IHH -NV) have caused serious outbreaks of disease in shrimp farmed in the Americas (Lightner 1996p.…”