Infection levels and seasonality of monogeneans in the largemouth bass Micropterus salmoides (Perciformes: Centrarchidae) from Nuevo León, Mexico.

Largemouth bass, Micropterus salmoides, is a native fish species with special importance for sport fishing competitions in Nuevo León, Mexico. However, no study has investigated the parasitic fauna of M. salmoides, and no reports are available on monogenean parasites in this fish species. Therefore, we described the monogenean parasites of M. salmoides and the effects of season and fish condition factor in five reservoirs: La Boca (LB), El Cuchillo-Solidaridad (CS), Sombreretillo (S), Laguna Salinillas (LS) and Cerro Prieto (CP). The monogeneans infecting M. salmoides were Clavunculus unguis and Acolpenteron ureteroecetes (collected in all localities), as well as Syncleithrium fusiformis, Haplocleidus furcatus, Clavunculus bifurcatus and Urocleidus principalis (CS). Clavunculus unguis had the highest prevalence in fish from all reservoirs. The abundance of monogeneans was generally greater in late spring to autumn than in winter. Although season was not correlated with abundance (r s = 0.0934, P <  0.0154), the months of highest temperature (from May to September) were positively correlated with parasite abundance. A significant association was observed between fish condition factor and the presence of monogeneans (P <  0.05), except for A. ureteroecetes. Our findings include five new geographic records for C. unguis, S. fusiformis, H. furcatus and C. bifurcatus.

Nucleotide sequence variations of the major structural proteins (VP15, VP19, VP26 and VP28) of white spot syndrome virus (WSSV), a pathogen of cultured Litopenaeus vannamei in Mexico.

White spot syndrome virus (WSSV) was first reported in farmed Litopenaeus vannamei stocks in Sinaloa and Sonora, Mexico during 1999 and continues to cause severe shrimp losses. WSSV genes encoding nucleocapsid (VP26 and VP15) and envelope proteins (VP19 and VP28) of a Mexican isolate were cloned in the pMosBlue vector. The nucleotide sequences of these genes were compared with WSSV isolates in GenBank. VP15 is highly conserved, and VP26 showed 99% homology to a Chinese isolate. The VP28 fragment demonstrated 100% homology to the majority of the isolates analysed (UniProt accession no. Q91CB7), differing from two Indian WSSV and one Chinese WSSV isolates by two non-conserved and one conserved replacements, respectively. Because of their highly conserved nature, these three structural proteins are good candidates for the development of antibody-based WSSV diagnostic tools or for the production of recombinant protein vaccines to stimulate the quasi-immune response of shrimp. In contrast, VP19 of the Mexican isolate was distinguishable from almost all isolates tested, including an American strain of WSSV (US98/South Carolina, GenBank accession no. AAP14086). Although homology was found with isolates from Taiwan (GenBank accession no. AAL89341) and India (GenBank accession no. AAW67477), VP19 may have application as a genetic marker.

[Parasite prevalence and intensity in Mugil cephalus (Pisces: Mugilidae), from Colorado River, Baja California, Mexico]. / Prevalencia e intensidad parasitaria en Mugil cephalus (Pisces: Mugilidae), del Río Colorado, Baja California, México.

The parasitic prevalence and mean intensity in the striped mullet, Mugil cephalus, was seasonally determined during an annual cycle (February 1994 to February 1995) in the confluence of the Colorado and Hardy rivers, Baja California, México. Two species of parasites were identified, a nematode, Contracaecum multipapillatum (von Drasche, 1882) (Ascaridida: Anisakidae), and a copepod, Ergasilus versicolor Wilson, 1911 (Poecilostomatoida: Ergasilidae). The larvae of C. multipapillatum, which were represented by two size classes (A and B stages), had prevalences of 30% and 14.5%, respectively; while A. versicolor had a prevalence of 72.7%. The mean intensity of C. multipapillatum was 6.18 and 2.37 individuals per infected fish for A and B stages, respectively; and for A. versicolor, it was of 4.01. The number of parasites (taxa combined) increased with the size of fish (r = 0.22, p = 0.02), but it was independent of the host's condition factor (KSL).

[First report on Neotoma micropus (Rodentia) as a reservoir of Trypanosoma cruzi in Mexico]. / Primer reporte de Neotoma micropus (Rodentia) como reservorio de Trypanosoma cruzi en México.

Using xenodiagnosis, two (8.0%) of 25 woodrats Neotoma micropus were found infected with tripanosome parasite in Vaquerias, a village in Nuevo Leon State, Mexico. The triatomine species developing infective metacyclic trypanosomes at week 12th were Triatoma pallidipennis, T. infestans and T. gerstaeckeri. Experimental infections using infected dejections were successfully conducted on laboratory mice (CD1 strain) confirming the vertebrate cycle of Trypanosome cruzi. The biological characterization of T. cruzi strains was demonstrated based on: 1) Triatomine developmental cycle. 2) A vertebrate host parasitic period up to 25-33 post-infection days, and. 3) Typical morphology of bloodstream trypomastigotes and amastigotes from myocardial nest. This is the first report of T. cruzi biologically characterized in Nuevo Leon, as well as a new report of N. micropus, increasing the list of reservoir hosts in Mexico.

[Histotropism and pathogenicity of Trypanosoma cruzi in albino mice (NHI) isolated from triatomines in Nuevo Leon, Mexico]. / Histotropismo y patogenicidad de Trypanosoma cruzi en ratón albino (NHI) aislado de triatominos en Nuevo León, México.

The neolonese strain of Trypanosoma cruzi was obtained from deyections of nosed bugs (Triatoma gerstaeckeri) which were caught in General Teran and Dr. Coss, Nuevo Leon. This strain was kept alive for passing it from mouse-triatomines and vice versa. Posteriorly, nests of amastigotes were found in skeletal and myocardial muscle fibers from albinous mouse Mus musculus NHI by using light microscopy and electron microscopy. In consequence, the parasitic element was classified as a myotropic strain, although it was observed in less amount in liver, kidney and spleen. Main pathological changes observed were intersticial inflammation, disruption of muscle fibers, myocarditis, mitochondrial alteration and cytoplasmic vacuolation.

Sarcocystis neotomafelis sp. n (Protozoa; Apicomplexa) from the woodrat Neotoma micropus in Mexico.

The developmental cycle of a new species of Sarcocystis (S. neotomafelis) was investigated. Cysts obtained from the muscle fibers of the woodrats were given orally to 19 laboratory newborn kittens, 5 pups and 5 crotalids. Infection developed only in newborn kittens. Macrogametes, microgamonts and immature oocysts were observed principally in the jejunum. Immature oocysts were detected at 6-21 post infection days. Based on morphological observations made by light and electron microscopy, and repeating transmission experiments, S. neotomafelis is described as a new species. Also the prevalence of cysts and the statistical frequency of sarcocystosis according to location and hosts's sex are given. This is the first species described in Mexico, and also the first report for Neotoma.