Location also matters: The oxidative response of the intertidal purple mussel Perumytilus purpuratus during tidal cycle.

For sessile intertidal organisms, periods of low tide impose both cellular and physiological challenges that can determine bathymetric distribution. To understand how intertidal location influences the cellular response of the bivalve Perumytilus purpuratus during the tidal cycle (immersion-emersion-immersion), specimens from the upper intertidal (UI) and lower intertidal (LI) of bathymetric distribution were sampled every 2 h over a 10-h period during a summer tidal cycle. Parallelly, organisms from the UI and LI were reciprocally transplanted and sampled throughout the same tidal cycle. Levels of oxidative damage (lipid peroxidation and protein carbonyls) as well as total antioxidant capacity and total carotenoids were evaluated as cellular responses to variations in environmental conditions throughout the tidal cycle. The results indicate that both the location in the intertidal zone (UI/LI), the level of aerial exposure, and the interaction of both factors are determinants of oxidative levels and total antioxidant capacity of P. purpuratus. Although oxidative damage levels are triggered during the low tide period (aerial exposure), it is the UI specimens that induce higher levels of lipid peroxidation compared to those from the LI, which is consistent with the elevated levels of total antioxidant capacity. On the other hand, organisms from the LI transplanted to the UI increase the levels of lipid peroxidation but not the levels of protein carbonyls, a situation that is also reflected in higher levels of antioxidant response and total carotenoids than those from the UI transplanted to the LI. The bathymetric distribution of P. purpuratus in the intertidal zone implies differentiated responses between organisms of the lower and upper limits, influenced by their life history. A high phenotypic plasticity allows this mussel to adjust its metabolism to respond to abrupt changes in the surrounding environmental conditions.

Upwelling as a stressor event during embryonic development: Consequences for encapsulated and early juvenile stages of the marine gastropod Acanthina monodon.

Upwelling phenomena alter the physical and chemical parameters of the sea's subsurface waters, producing low levels of temperature, pH and dissolved oxygen, which can seriously impact the early developmental stages of marine organisms. To understand how upwelling can affect the encapsulated development of the gastropod Acanthina monodon, capsules containing embryos at different stages of development (initial, intermediate and advanced) were exposed to upwelling conditions (pH = 7.6; O2 = 3 mg L-1; T° = 9 °C) for a period of 7 days. Effects of treatment were determined by estimating parameters such as time to hatching, number of hatchlings per capsule, percentage of individuals with incomplete development, and shell parameters such as shell shape and size, shell strength, and the percentage of the organic/inorganic content. We found no significant impacts on hatching time, number of hatchlings per capsule, or percentage of incomplete development in either the presence or absence of upwelling, regardless of developmental stage. On the other hand, latent effects on encapsulated stages of A. monodon were detected in embryos that had been exposed to upwelling stress in the initial embryonic stage. The juveniles from this treatment hatched at smaller sizes and with higher organic content in their shells, resulting in a higher resistance to cracking 30 days after hatching, due to greater elasticity. Geometric morphometric analysis showed that exposure to upwelling condition induced a change in the morphology of shell growth in all post-hatching juveniles (0-30 days), regardless of embryonic developmental stage at the time of exposure. Thus, more elongated shells (siphonal canal and posterior region) and more globular shells were observed in newly hatched juveniles that had been exposed to the upwelling condition. The neutral or even positive upwelling exposure results suggests that exposure to upwelling events during the encapsulated embryonic phase of A. monodon development might not have major impacts on the future juvenile stages. However, this should be taken with caution in consideration of the increased frequency and intensity of upwelling events predicted for the coming decades.

Embryonic encapsulated development of the gastropod Acanthina monodon is impacted by future environmental changes of temperature and pCO2.

Egg capsules of the gastropod Acanthina monodon were maintained during the entire period of encapsulated development at three temperatures (10, 15, 20 °C) and two pCO2 levels (400, 1200 µatm). Embryos per capsule, size at hatching, time to hatching, embryonic metabolic rates, and the resistance of juveniles to shell breakage were quantified. No embryos maintained at 20 °C developed to hatching. The combination of temperature and pCO2 levels had synergistic effects on hatching time and developmental success, antagonistic effects on number of hatchlings per capsule, resistance to juvenile shell cracking and metabolism, and additive effect on hatching size. Juveniles hatched significantly sooner at 15 °C, independent of the pCO2 level that they had been exposed to, while individuals hatched at significantly smaller sizes if they had been held under 15 °C/1200 µatm rather than at 10 °C/low pCO2. Embryos held at the higher pCO2 had a significantly greater percentage of abnormalities. For capsules maintained at low pCO2 and 15 °C, emerging juveniles had less resistance to shell breakage. Embryonic metabolism was significantly higher at 15 °C than at 10 °C, independent of pCO2 level. The lower metabolism occurred in embryos maintained at the higher pCO2 level. Thus, in this study, temperature was the factor that had the greatest effect on the encapsulated development of A. monodon, increasing the metabolism of the embryos and consequently accelerating development, which was expressed in a shorter intracapsular development time, but with smaller individuals at hatching and a lower resistance of their shells to breakage. On the other hand, the high pCO2 level suppressed metabolism, prolonged intracapsular development, and promoted more incomplete development of the embryos. However, the combination of the two factors can mitigate--to some extent--the adverse effects of both incomplete development and lower resistance to shell breakage.

First-Pass Effect in M1-Occlusion Stroke Patients Treated with Combined Stent-Retriever/Large-Bore Distal Aspiration Catheter Thrombectomy.

INTRODUCTION: Combined stent-retriever/large-bore distal aspiration catheter (LB-DAC) thrombectomy was recently introduced to treat large-vessel occlusion; however, it is unclear whether larger inner diameters improve outcomes. We compared angiographic and clinical outcomes in patients with occlusions of the M1 segment of the middle cerebral artery treated with mechanical thrombectomy using extra-LB-DAC versus LB-DAC in combination with stent-retrievers. METHODS: We analyzed consecutive patients with M1 occlusion included in the ROSSETTI registry treated with non-balloon guide catheter combined LB-DAC/stent-retriever thrombectomy between June 2019 and April 2022. We compared demographics, baseline clinical variables, procedural variables, angiographic outcomes, and clinical outcomes [National Institute of Health Stroke Scale score at 24 h (24h-NIHSS) and modified Rankin scale score at 3 months] between patients treated with extra-LB-DAC (Sofia Plus, MIVI Q6, Catalyst7; inner diameter, 0.068″-0.070″) versus LB-DAC (Sofia 5F, MIVI Q5, Catalyst 6; inner diameter, 0.055″-0.064″). Primary outcome was the first-pass effect (FPE) rate, defined as near-complete/complete reperfusion (mTICI 2c-3) after a single pass of the device. RESULTS: We included 324 patients (extra-LB-DAC, 185, 57.1% patients). Demographics, clinical data, and clinical outcomes were similar between the two groups; however, there was a trend towards improvement in National Institute of Health Stroke Scale score at 24 h (24h-NIHSS) in the cohort treated with extra-LB-DAC 9 points (IQR 4;16 points) vs. 12 points (IQR 4;18 points, P = 0.083). Patients treated with extra-LB-DAC had higher FPE rate (47% vs. 30.9%; P = 0.003) and higher modified FPE (mTICI ≥ 2b after a single pass) rate (65.9% vs 46.8%; P = 0.001). The use of extra-LB-DAC was an independent factor in predicting FPE (odds ratio 1.982, 95% confidence interval 1.250-3.143, P = 0.004). CONCLUSION: Our results suggest that in combined LB-DAC/stent-retriever thrombectomy, a larger aspiration catheter inner diameter is associated with higher rates of FPE and mFPE.

UV-R mitigation strategies in encapsulated embryos of the intertidal gastropod Acanthina monodon: A way to compensate for lack of parental care.

Intracapsular embryonic development in the intertidal zone exposes embryos to various stress sources characteristic of this environment, including UV-R. They require defensive mechanisms to mitigate its adverse effects. The presence of total carotenoids (TC), and mycosporine-like amino acids (MAAs) was studied in adults, in encapsulated embryos, and in the egg capsule walls of the intertidal gastropod Acanthina monodon. Oxygen consumption rates (OCR) were determined in encapsulated and excapsulated embryos exposed to photosynthetically active radiation (PAR) and PAR + UV-A + UV-B to understand if the capsule wall is a protective structure for encapsulated embryos. The results showed the presence of TC in adult pedal and gonad tissues, and in all encapsulated stages. MAAs were not detected. The physical structure of the capsule wall retained most wavelengths, being particularly efficient in the UV-B range. Excapsulated embryos exposed to PAR + UV-A + UV-B radiation increased its OCR compared to encapsulated embryos, indicating the protective character of the capsule wall.

Long-term effects of contrasting pCO2 levels on the scope for growth in the carnivorous gastropod Concholepas concholepas.

We evaluated the effect of contrasting pCO2 levels: lower (390 µatm), moderate (700 µatm) and extreme (1000 µatm), on the scope for growth of the keystone snail Concholepas concholepas over an exposure period of 6 months. Juvenile snails were collected from rocky intertidal habitats and acclimated for 5 months to those pCO2 levels. Subsequently, three groups of snails were randomly taken (n = 7 for each treatment) and reared for an additional 1 month for each of the three pCO2 levels. Physiological traits related with energy gain and energy expenditure were quantified. The scope for growth index decreased significantly with increases in pCO2, yielding negative values throughout the experimental period for the snails exposed to 1000 µatm pCO2, probably due to the extra energy required to maintain their metabolic functions in balance. This suggests that future climate change scenarios with elevated pCO2 levels could threaten the growth and other basic functions of juvenile snails of this species.

Relationship between over-crowding within egg capsules of the marine gastropod Acanthina monodon and prospects for juvenile success.

Encapsulated development with extraembryonic yolk may lead to competition for nutrients within egg capsules. In this research, different degrees of competition among embryos in subtidal egg capsules of Acanthina monodon resulted in considerable differences in hatching size. For newly hatched juveniles, individuals hatching from less crowded egg capsules showed better survival, larger SL, higher rates of oxygen consumption, and higher rates of food consumption. However, by 28 days after hatching, the largest surviving juveniles were the best-performing individuals, regardless of the initial embryo density within the capsules. In summary, more crowded egg capsules resulted in poorer survival. These findings may help to explain the variability seen in juvenile success in some field populations; much of that variation may reflect stressful experiences that the new recruits have had during the early stages of their encapsulated development.

Energetic trade-offs: Implications for selection between two bivalve prey species by a carnivorous muricid gastropod.

Active predators obtain energy and nutrients from prey through complex processes in which the energy gained must exceed the energy invested in finding and ingesting the prey. In addition, the amount of energy available will vary with the prey that are selected for consumption. The muricid gastropod Acanthina monodon inhabits rocky shores, where it routinely feeds on the mytilids Semimytilus algosus and Perumytilus purpuratus. In this study, S. algosus was highly preferred by the predator (over 90% were eaten) versus P. purpuratus (only 9% were eaten) when offered a mixed diet. The energetic cost of attacking one S. algosus individual was 91 J bivalve-1 while for P. purpuratus it was slightly higher: 95 J bivalve-1. Also, whereas A. monodon required on average 19 h to consume S. algosus, successful attacks on P. purpuratus required about 32% more time (25 h). In addition, a longer resting time was needed by the predator after preying on P. purpuratus before it initiated another attack. Moreover, the active metabolic costs associated with successfully attacking the prey increased 3.2 times over the basal metabolic costs when attacking S. algosus, but only by 2.5 times when attacking P. purpuratus. The calculations associated with preying on each species showed that the energetic gain per unit time likely accounts for the predator's preference for attacking S. algosus, even though predation on both species provided net energy gains for the predator. However, as S. algosus occurs seasonally at our study site, P. purpuratus would probably also be consumed due to its constant availability throughout the whole year.

Respiratory and desiccation constraints during encapsulated intertidal development of the marine gastropod Acanthina monodon.

Acanthina monodon commonly deposits its egg capsules in the intertidal zone. Capsule aerial exposure during low-tide can impact oxygen consumption rates (OCR) of embryos and intracapsular oxygen availability, and expose embryos to desiccation. OCR increased as embryonic development progressed, and was greater when capsules were submerged in seawater than when exposed to air. Oxygen available within the capsule was always less than that available in the immediate external environment, whether capsules were immersed or exposed. The highest internal oxygen concentrations were recorded during periods of air exposure for embryos in more advanced development stages. When exposed to air, capsules lost water the fastest when they contained early embryos, and suffered the highest mortalities following exposure. Collectively, these data suggest that, although encapsulation helps the embryos to develop across wildly fluctuating environmental conditions, the amount of stress the embryos experience will vary depending on their exact positioning within the intertidal zone.

Possible Mechanisms of Hatching from Egg Capsules in the Gastropods Crepipatella dilatata and Crepipatella peruviana, Species with Different Modes of Early Development.

Many invertebrates enclose their embryos within egg capsules, from which the offspring hatch. In marine gastropods that brood their egg capsules, hatching could involve radular activity by the mother or by unhatched stages, increased osmotic concentration of the intracapsular fluid, or production of hatching enzymes. The present research sought to determine whether mechanical action by the brooding female or by the encapsulated embryos was involved in the hatching for two sympatric and closely related species of calyptraeid: Crepipatella dilatata, which exhibits direct development without free-living larvae, and Crepipatella peruviana, which releases free-living veliger larvae. We also considered the role that enzymatic action or osmotic changes in the intracapsular fluid might play in hatching. Using scanning electron micrograph analyses, we found no evidence that the well-developed, pre-hatching juvenile radula of C. dilatata played any role in the hatching process and that the radula of C. peruviana did not even develop until long after hatching; so there was no evidence of radular activity involved in the hatching of either species. For C. peruviana, the intracapsular fluid osmolality was always higher than that of the surrounding seawater, suggesting that there is a strong natural water inflow during development. Moreover, when egg capsules of C. peruviana were exposed to lower ambient salinities, the substantial entry of water correlated well with high percentages of hatching, particularly for egg capsules containing advanced veligers, suggesting that an osmotic mechanism may be involved in the hatching process of this species. In contrast, hatching in C. dilatata appeared to be enzymatically mediated.

Volcanic ash in the water column: Physiological impact on the suspension-feeding bivalve Mytilus chilensis.

Ashes settling into the sea from volcanic explosions expose suspension-feeding species to reduced seston quality. Adults and juveniles of the mussel Mytilus chilensis were exposed for 15days to the phytoplankton Isochrysis galbana together with various concentrations of ashes. We then quantified impact on survival and physiology. Although no individuals died during the experiment, by the end of the study clearance rates and oxygen consumption rates had decreased substantially, and tissue weight of mussels exposed to the highest ash concentrations declined substantially. Gills showed no physical damage, but did show abundant mucus secretion in response to ash particles. Moreover, as the relative proportions of microalgae to ash in the diet decreased, individuals showed increasing preferential ingestion of microalgal particles. Increased ash content in the diet altered physiological rates and activated distinct particle selection with a high production of pseudofeces and high energy costs, with potential long-term consequences.

Nódulos eritematosos con distribución lineal / Erithematous nodules with linear distribution

No disponible

Embryonic velar structure and function of two sibling species of Crepidula with different modes of development.

The structure and function of the embryonic velum of two closely related species of Crepidula with different modes of development are examined. The velum of C. dilatata, a direct developer whose embryos feed on nurse eggs, does not differ substantially from the velum of C. fecunda, a species with planktotrophic larvae. Although velar ciliation develops earlier in embryos of C. dilatata, embryos of both species were able to feed on small particles, using the opposed-band ciliary mechanism. However, the embryos of C. dilatata lose this ability as they grow. The embryos of C. dilatata were not able to swim, whereas those of C. fecunda swam consistently in vials of seawater. This difference in swimming ability is probably due to differences in velum-body size allometry between the two species.

The 5'-flanking sequence and regulatory elements of the cystatin S gene.

The gene encoding rat cystatin S (Cys S), a salivary gland-specific secretory protein, has CAAT and TATA boxes upstream of the inititation codon (Cox and Shaw, 1992), and contains regions that resemble those of other hormonally responsive eukaryotic genes. The 5'-flanking sequence of the rat Cys S gene has a potential CREB/AP-1 binding site (Rupp et al., 1990; Trejo et al., 1992), two potential glucocorticoid responsive elements (GREs, Drouin et al., 1989), and a possible GR/PR (glucocorticoid/progesterone) responsive element (Forman and Samuels, 1990). One of these potential GREs is adjacent to a potential AP-2 binding site, and another is typical of the glucocorticoid and progesterone receptor binding site. In this report, we have identified three regions in the 5'-flanking region of the Cys S gene that are found in salivary gland-specific genes (Ting et al., 1992) with a GT-rich region located between conserved elements II and III. Transfection experiments described in this paper suggest that a 281-bp DNA fragment from the Cys S gene promoter region with conserved elements II and III, the GT-rich region, and a possible GR/PR responsive element contains a negative regulatory element. In addition, our experiments suggest that the GT-rich region by itself is acting as a positive regulatory element.

The Velar Ciliature in the Brooded Larva of the Chilean Oyster Ostrea chilensis (Philippi, 1845).

The Chilean oyster (Ostrea chilensis) broods its offspring almost to the settlement stage (about 8 weeks). Larvae are maintained inside the infrabranchial chamber of the female. Samples from all embryo and larval developmental stages were obtained from mantle cavities of brooding females and analyzed by scanning electron microscopy, with particular attention to the velar structures. All embryos and the earliest veliger stages of O. chilensis are devoid of cilia. Cilia first appear when shell length reaches 290-300 {mu}m, and the first cilia to grow on the velum form the outer preoral cilia. In larvae 340 {mu}m long, all the ciliary rings on the velum can be distinguished. These are the apical cilia (AC), inner preoral cilia (IPC), outer preoral cilia (OPC), and adoral cilia (AOC). The absence of the apical tuft in both O. chilensis and the closely related species O. edulis represents an adaptation to brooding by the embryos and larvae, but the lack of the postoral cilia (POC) in O. chilensis and the lack of cilia in the embryonic and early veliger stages are associated with an extreme brooding condition in this species.

Isoproterenol-induced expression of the cystatin S gene in submandibular glands of parasympathectomized rats.

Parasympathetic innervation of rat submandibular and parotid glands regulates saliva volume, its rate of secretion and its composition. It also has a regulatory role in hypertrophy and hyperplasia of salivary glands, and in the expression of specific sets of genes. Rat cystatin S is a member of family 2 of the cysteine proteinase inhibitor superfamily. Cystatin S gene expression is tissue- and cell type-specific, temporally regulated during postnatal development, and not observed in adult animals. Isoproterenol (IPR), a beta-adrenergic agonist, induces hypertrophic and hyperplastic enlargement of rat salivary glands and expression of a number of genes including cystatin S. Sympathectomy reduces, but does not completely block IPR-induced expression of the cystatin S gene in the submandibular glands of adult female rats, indicating the participation of sympathetic factor(s) in this regulation. Since both sympathetic and parasympathetic branches of the autonomic nervous system act in parallel in the submandibular gland, it is possible that parasympathetic nerve terminals also provide factor(s) that play a role in regulation of cystatin S gene expression. Experiments described in this paper were designed to test the hypothesis that the parasympathetic nervous system participates in IPR-induced cystatin S gene expression. Bilateral parasympathectomy reduced IPR-induced cystatin S gene expression, suggesting a role of the parasympathetic nervous system in its regulation. Unilateral parasympathectomy in contrast, had no effect on IPR-induced cystatin S gene expression, suggesting that the presence of an intact parasympathetic innervation in the contralateral side permits the 'normal' IPR-induced expression of the cystatin S gene in the parasympathectomized gland.

Effect of sympathetic innervation on isoproterenol-induced cystatin S gene expression in rat submandibular glands during early development.

The rat submandibular gland is innervated by both sympathetic and parasympathetic branches of the autonomic nervous system which, in turn, regulate the secretory function of the gland. Parasympathetic innervation of rat submandibular glands is present at birth; in contrast, sympathetic innervation reaches the glands by postnatal day 5. Isoproterenol (IPR), a beta-adrenoreceptor agonist, induces hypertrophic and hyperplastic enlargement of rat salivary glands, and induces the expression of a number of genes, including cystatin S (Cys S), a member of family 2 of the cysteine proteinase inhibitor superfamily. Cys S gene expression is tissue specific, cell type specific, occurs temporally during normal development and is not observed in adult animals unless stimulated by IPR. In addition, sympathectomy of adult rat submandibular glands reduced IPR-induced expression of the Cys S gene. This paper reports experiments analyzing the participation of the sympathetic branch of the autonomic nervous system in IPR-induced expression of the cystatin S gene during early development of the submandibular gland. The rat Cys S gene could be induced by IPR by day 3, and the level of Cys S mRNA remained constant until 8 days at which time a dramatic IPR induction of Cys S mRNA was observed. This statistically significant increase in Cys S mRNA at 8 days was diminished, but not completely suppressed, upon sympathectomy of 1-day-old animals. These data indicate that an intact sympathetic innervation is not a requisite for IPR-induced Cys S gene expression in developing submandibular glands; however, sympathetic innervation is required for the full IPR response of the Cys S gene in developing submandibular glands. The developmental experiments presented in this paper indicate that factor(s) coming from the sympathetic nervous system participate in IPR-induced expression of the Cys S gene in rat submandibular glands.

Effect of sympathectomy on isoproterenol-induced expression of the cysteine proteinase inhibitor gene, cystatin S, in rat submandibular glands.

The autonomic nervous system regulates the secretory function of salivary glands. The volume, rate of secretion and composition of saliva are regulated by both sympathetic (alpha 1-, alpha 2 and beta 1-adrenergic) and parasympathetic (muscarinic and cholinergic) receptor systems. The rat cystatin S gene, a member of family 2 of the cysteine proteinase inhibitor superfamily, has a very defined pattern of expression during the postnatal development of the rat submandibular gland. Its expression is not detected in the fetus or in rats up to three weeks of age. After this time, the amount of cystatin S mRNA increases, reaching a conspicuously high concentration at 28 days, and then it declines to a barely detectable level at 32 days of age; cystatin S mRNA is not detectable in the glands of adult animals. However, the beta-adrenoreceptor agonist isoproterenol (IPR) induces high concentrations of cystatin S mRNA in the submandibular gland in vivo. This paper reports experiments analysing the participation of the sympathetic nervous system in the IPR-induced expression of the cystatin S gene. Sympathetic denervation (unilateral and bilateral) by removing the superior cervical ganglion 14 days before a single injection of IPR reduced the expression of the cystatin S gene. Chemical denervation by reserpine (a drug that depletes neurotransmitters in sympathetic nerve terminals) also reduced IPR-induced expression of the gene. Morphological analyses of sympathectomized and reserpine-treated glands showed that the structure of the gland was similar to that of glands of intact animals and to those not treated with reserpine. The hypertrophic response to IPR was less obvious in the sympathectomized glands, but was similar in reserpine treated animals. Collectively, these data suggest that even in the presence of a functional beta 1-adrenergic receptor pathway, factor(s) from the sympathetic nervous system may be required for IPR-induced expression of the cystatin S gene.

Prevalencia de parásitos intestinales en niños menores de 5 años con diarrea a tendidos en centros asistenciales de la Ciudad de Maracaibo / Interic parasites prevalence in less than five years old diarrhoeal children from medical centers of Maracaibo City

Con el fin de determinar la prevalencia de parásitos intestinales fueron examinados 418 muestras fecales. El grupo de niños fue dividido en dos grupos etarios: menores de 1 año y de 1-4 años. A todas las muestras fecales se les practicó frotis húmedo con solución salina y teñido en lugol para investigar helmintos y protozoarios, así como también seco teñido con Ziehl-Neelsen modificada para Crypstosporidium sp. Heces con trofozoitos de amibas fueron coloreadas con azul de metileno amortiguado. La prevalencia parasitaria fue del 34.9 por ciento con predominio de protozoarios (29.9 por ciento) sobre los helmintos (10.5 por ciento); las especies más frecuentes fueron: G.lamblia 11.0 por ciento B.hominis 10.3 por ciento, Cryptosporidium sp 7.4 por ciento, T.trichiura 6.2 por ciento, A.lumbricoides 5.9 por ciento y E.histolytica 5.7 por ciento; estos resultados son semejantes a los obtenidos en nuestro estudio previo. G.lamblia fue el parásito más frecuente en todos los Municipios Sanitarios de la ciudad y en el grupo etario de 1-4 años de edad (17.9 por ciento). Con estos estudios se inicia la búsqueda y reporte de Cryptosporidium sp y B.hominis en niños menores de 5 años con diarrea en nuestra región; Cryptosporidium sp fue el parásito más frecuente en el grupo etario menores de 1 año. Sólo Cryptosporidium sp, T.trichiura y B.hominis se presentaron con frecuencias muy variables (X²S) según el Municipio Sanitario investigador esto demuestra que los parásitos intestinales pueden registrarse con niveles endémicos variables según el área bajo estudio. Se recomienda continuar la investigación de parásitos intestinales en la misma zona sanitaria e iniciarla en otras