Área Clínica Médica - 5º año: Patologías infecciosas endémicas II

Introducción a las Parasitosis Endémicas

Teniasis: Definición y Tipos

• La doctora Sandra Grillen presenta el tema de la parasitosis endémica, comenzando con la teniasis, específicamente la Taenia solium y Taenia saginata .

Ciclo de Vida de Taenia saginata

• El huésped definitivo es el ser humano, mientras que el ganado vacuno actúa como huésped intermediario. La infección se produce por el consumo de carne cruda infectada con larvas de T. saginata .

• Este parásito puede medir entre 5 y 25 metros y se compone de tres partes: escólex, cuello y cuerpo (estróbilo) formado por proglótides .

Proceso Infeccioso

• Los huevos llegan al suelo a través de materia fecal humana, son ingeridos por ganado, eclosionan en su intestino y forman cisticercos en los músculos del ganado .

• Cuando un humano consume carne cruda o mal cocida, el escólex se adhiere a la mucosa intestinal y comienza a desarrollarse en proglótides dentro del intestino delgado .

Ciclo de Vida de Taenia solium

• En este caso, tanto el hombre como el cerdo pueden actuar como huéspedes definitivos o accidentales. La fuente infecciosa también es la carne infectada .

• El parásito tiene una longitud entre 2 y 7 metros; sus partes también incluyen escólex, cuello y cuerpo compuesto por proglótides grávidas que contienen numerosos huevos .

Manifestaciones Clínicas

• Generalmente asintomáticas; sin embargo, pueden presentarse síntomas como meteorismo, dolor abdominal o náuseas. A veces se observa pérdida de peso o anorexia .

• Las proglótides pueden ser encontradas en ropa interior o cama del paciente; esto puede llevar al diagnóstico cuando no hay otros síntomas presentes .

Diagnóstico

Cisticercosis and Toxocariasis: Understanding Parasitic Infections

Cisticercosis Overview

• Cisticercosis is caused by the larval form of Taenia solium, leading to symptoms like leukocytosis and moderate eosinophilia. Treatment typically involves a single dose of praziquantel (10-25 mg/kg).

• When administering antiparasitics, especially for suspected Taenia solium infections, metoclopramide may be given to prevent vomiting. A purgative should follow to ensure complete elimination of the tapeworm.

Pathophysiology and Symptoms

• The infection can manifest in various tissues, with a 7% infection rate reported in Latin America. The oncosphere transforms into a cysticercus within 2-3 months, surrounded by collagen that separates it from host tissue.

• Clinical manifestations are often nonspecific and depend on lesion number and location. Increased inflammatory response occurs when cysts die spontaneously or through treatment.

Prevention Strategies

• Preventive measures focus on avoiding contamination from human feces in soil, water, or food sources. This intervention disrupts the transmission cycle effectively.

Neurocysticercosis Implications

• Neurocysticercosis can significantly affect the brain, potentially causing seizures, headaches, increased intracranial pressure, and other neurological symptoms due to cyst presence in cerebral structures.

• Other locations affected include eyes (uveitis), subcutaneous tissue, muscles, spinal cord, heart, lungs, bones; prevention remains crucial against fecal contamination.

Diagnosis and Treatment Approaches

• Diagnosis begins with an epidemiological assessment followed by clinical evaluation. Imaging techniques like CT scans or MRIs help identify asymptomatic cases outside the CNS.

• Laboratory tests may reveal hyperproteinorrhachia or lymphocytic pleocytosis in cerebrospinal fluid (CSF). ELISA tests show high specificity (98%) and sensitivity (~100%).

• Treatment options include albendazole (15 mg/kg/day for 8 days) or praziquantel (50 mg/kg/day over 15–30 days). Corticosteroids are recommended alongside treatment for inflammatory responses in CNS cases.

Toxocariasis Overview

• Toxocariasis is caused by Toxocara canis (dog roundworm), primarily affecting humans through ingestion of eggs from contaminated soil via dog feces.

Transmission Dynamics

• Dogs serve as primary hosts for Toxocara canis, transmitting larvae to puppies during gestation. Infected puppies shed eggs in their feces which pose risks to children who may ingest them while playing outdoors.

Parasitic Infections in Children

Understanding the Risks and Symptoms

• The discussion begins with the behavior of dogs, particularly how they may lick their feces, which can lead to children inadvertently ingesting larvae. This can result in serious health implications for young children.

• Systemic manifestations of parasitic infections include anorexia, fatigue, irritability, fever, skin issues (eczema, erythema), joint pain, hepatomegaly, cholestasis signs, wheezing, and even epilepsy.

• A critical concern is unilateral chorioretinitis in children that can lead to a significant decrease in visual acuity (up to 93%). Other symptoms may include exotropia and leukocoria; only 7% of affected individuals retain acceptable vision.

Differential Diagnosis

• The differential diagnosis includes retinoblastoma due to similar ocular presentations. Fundoscopic examination reveals signs consistent with both conditions.

• If not diagnosed correctly as a parasitic infection and treated promptly, there is a risk of losing vision or mistakenly performing an enucleation for what could be a treatable condition.

Diagnostic Considerations

• Key ocular signs include leukocoria and strabismus. Additional symptoms may involve eye pain or redness.

• Important diagnostic factors include geophagia (eating dirt), contact with uninfected puppies/kittens, intense eosinophilia alongside leukocytosis. Serological tests have variable sensitivity (70%-91.3%) and specificity (76.9%-100%).

Treatment Options