RESUMEN
Harmful algae blooms (HABs) are a conspicuous phenomenon that affect the coastal zone worldwide. Aquaculture industry zones are not excluded from being affected by HAB that cause organism mortality and jeopardize their innocuity due to the contamination by phytotoxins with the concomitant economic losses. Direct ingestion of metabolites from HAB species or organisms contaminated with phycotoxins together with dermal absorption of dissolved metabolites (DM), including toxins, are the two main routes of poisoning. From these poisoning routes, the effect of DM, particularly paralytic shellfish toxins (PST), has been relatively understudied. This intoxication route can be conspicuous and could be involved in many significant mortalities of cultivated marine organisms. In this study, white shrimp juveniles (2.1 g wet weight) of Litopenaeus vannamei were exposed to extracts of 104, 105 and 106 cells/L of the dinoflagellate Gymnodinium catenatum, a PST producer. The experiment ended after 17 h of exposure when shrimps exposed to 106 cells/L extract started to die and the rest of the shrimps, from this and other treatments, did not respond to gentle physical stimulus and their swimming activity was low and erratic. Toxin concentrations were determined using high performance liquid chromatography while qualitative and quantitative histological damages were assessed on the tissues. In general, most toxins were accumulated in the hepatopancreas where more than 90% were found. Other tissues such as intestine, muscle, and gills contained less than 10% of toxins. Compared to the control, the main significative tissue damages were, loss of up to 80% of the nerve cord, 40% of the muscle coverage area, and reduction of the gill lamella width. Also, atrophy in hepatopancreas was observed, manifested by a decrease in the height of B cells, lumen degeneration and thinning of tubules. Some damages were more evident when shrimps were exposed to higher concentrated extracts of G. catenatum, however, not all damages were progressive and proportional to the extract concentration. These data confirm that PST dissolved enter the shrimp, possibly via the gills, and suggest that dissolved metabolites, including PST, may cause tissue damage. Other dissolved metabolites produced by G. catenatum, alone or in synergy, may also be involved. These results also pointed out the importance of dissolved molecules produced for this dinoflagellate and the potential effect on cultured shrimp.
RESUMEN
We evaluated the incidence of anti-Dengue virus (DENV) antibodies and dengue viremia in a region of Mexico with a high prevalence of dengue. DENV is the most important arthropod-borne virus in terms of human morbidity and mortality in America We tested 800 blood donors from a tertiary care teaching hospital that provides care in Northeast Mexico, to identify anti-DENV IgM and IgG antibodies by enzyme-linked immunosorbent assay (ELISA) and DENV genome by reverse transcription polymerase chain reaction (RT-PCR). In addition, routine tests for donors including Brucella, Hepatitis C virus (HCV), Venereal Disease Research Laboratory (VDRL), HIV-1 and HBsAg identification were performed. We found that 59% of donors were reactive for anti-DENV IgG and none of them had reported recent DENV infection; however, 16 (2%) were reactive for anti-DENV IgM antibodies. None of them were viremic at the time of donation. Routine tests showed that the prevalence of anti-Brucella was 0.71%, anti-HCV 0.71%, anti-HIV-1-2 0.14%, HBsAg 0.14% and VDRL test 0.57%. Although DENV transmission by blood transfusion had not been confirmed in Mexico, the finding of a high prevalence of anti-DENV IgM-positive donors with asymptomatic manifestations and the recent viremia reported in blood donors suggests that this route of transmission might be possible.