Common Zoonotic Parasitic Infections and Prevention

Fascioliasis and the Liver Fluke

Fascioliasis is a zoonotic disease caused by a trematode parasite known as the liver fluke. In this cycle, humans and herbivores serve as definitive hosts, while small freshwater snails act as intermediate hosts.

The parasite, better known as Fasciola hepatica (referred to as 'pirihuín' in Chile), is a digenetic fluke. It has the appearance of a lanceolate leaf with a well-defined cephalic cone.

Symptoms and Clinical Picture

The clinical picture is characterized by a hypersensitive state and hepatobiliary symptoms. Symptoms vary by stage:

• Invasion Period: Pain, hepatomegaly (enlarged liver), fever, and urticaria.
• State Period: Digestive disorders, pain, jaundice, and fever.

Treatment and Prevention

Treatment: The primary treatment for fascioliasis is triclabendazole, which is widely used in veterinary medicine and for chronic infections in humans. It is administered orally.

Prevention: Efforts must focus on the destruction of snails to break the life cycle of the parasite. This includes sanitation measures for water, the rectification of water courses, and the drainage of wetland areas.

Transmission: Fasciola hepatica is found in the liver. The intermediate host is the snail (Caracol), and the definitive host is the human. Transmission occurs through the consumption of contaminated watercress.

Echinococcosis: Transmission and Risks

Echinococcosis is a parasitic disease that dogs can transmit to humans. The causal agents include Echinococcus granulosus (hydatid cyst), E. multilocularis, and E. vogeli.

Host and Infection Cycle

• Definitive Host: Canine.
• Intermediate Host: Herbivore.
• Human Infection: Humans are infected by ingesting dog feces or eating contaminated raw vegetables.
• Dog Infection: Dogs become infected by eating raw viscera.

Prevention and Hygiene Practices

To prevent infection, do not feed your dog raw viscera. Avoid being licked by dogs in the mouth. Always wash your hands with soap and water after petting a dog and before eating or handling food.

Trichinosis: Life Cycle and Infection

Trichinosis is caused by a small whitish nematode. The female is larger than the male and lives in the duodenal and jejunal mucosa. The infection begins by consuming meat containing larvae.

The Parasitic Life Cycle

After eating meat infected with larvae, the larvae are released into the gut where they grow. Following the insemination of females, the pregnant females are introduced into the intestinal submucosa. From there, they lay their larvae directly into the blood vessels. Parasitemia occurs, and circulating larvae enter the large irrigation muscles, where they are located intracellularly and encyst.

Epidemiology and Contagion

Trichinosis is a parasitic infection transmitted by carnivores among domestic and wild animals. The highest risk for humans is eating raw or undercooked meat that is infected.

Clinical Syndromes and Diagnosis

Most cases have little or no symptoms. The clinical picture depends on the load of microorganisms in the tissues. Severe cases can cause death through myocarditis or encephalitis.

Diagnosis: Based on clinical history, laboratory findings, CBC (complete blood count), and immunobiological reactions.

Medical Treatment and Prevention

Treatment:

• Albendazole: Possesses a high degree of absorption.
• Corticosteroids: Used in cases of severe fever and inflammation.

Prevention: Regarding pig rearing, there should be hygienic, well-built husbandry. For human safety, the centralization of slaughtering in appropriate establishments is vital. It is essential to educate the public about the importance of food safety and the proper cooking of meat.