Hydatid Disease Flashcards
What is Human Echinococcosis?
Human Echinococcosis is a zoonotic infection caused by larval forms (metacestodes) of tapeworms of the genus Echinococcus, typically found in the small intestine of carnivores like dogs and foxes. These carnivores are the normal hosts of the tapeworm.
Which Echinococcus species are pathogenic for humans?
The two Echinococcus species pathogenic for humans are E. granulosus and E. multilocularis.
How does the World Health Organization (WHO) distinguish between the diseases caused by E. granulosus and E. multilocularis?
The WHO designates the disease caused by E. granulosus as Cystic Echinococcosis (CE) and the disease caused by E. multilocularis as Alveolar Echinococcosis (AE).
Which Echinococcus species is relevant in South Africa?
In South Africa, only E. granulosus is relevant, causing Cystic Echinococcosis (CE).
What is the annual incidence of Cystic Echinococcosis (CE) in various endemic areas?
The annual incidence of CE can range from less than 1 to 200 cases per 100,000 inhabitants, depending on the endemic area.
How many people are at risk for Cystic Echinococcosis (CE) in China and Central Asia?
In China and Central Asia, more than 20 million people are at risk for Cystic Echinococcosis (CE).
What is the mortality rate for Cystic Echinococcosis (CE) in endemic areas?
The mortality rate for Cystic Echinococcosis (CE) is about 2-4% in endemic areas, although it can rise significantly if medical treatment is inadequate.
What is the annual incidence of Alveolar Echinococcosis (AE)?
The annual incidence of Alveolar Echinococcosis (AE) is generally low, ranging from 0.03 to 1.2 per 100,000 inhabitants.
What is the mortality rate for untreated or inadequately treated Alveolar Echinococcosis (AE)?
In untreated or inadequately treated patients, the mortality rate for Alveolar Echinococcosis (AE) exceeds 90% within 10-15 years of diagnosis.
Why is Echinococcosis considered a neglected disease?
Despite its significant socioeconomic impact and high mortality in untreated cases, Echinococcosis remains a neglected disease, often due to a lack of awareness and adequate medical resources in affected areas.
What is the most frequent presentation of Echinococcosis?
The most frequent presentation of Echinococcosis is Cystic Echinococcosis (CE).
What is the role of carnivores in the life cycle of Echinococcus granulosus?
Carnivores, such as dogs and foxes, are the definitive or final hosts in the life cycle of Echinococcus granulosus. The adult tapeworm lives in their intestines.
What are the intermediate hosts in the life cycle of Echinococcus granulosus?
Herbivores like sheep, goats, cows, and camels are the intermediate hosts. They ingest tapeworm eggs and are infected by them.
How do humans become involved in the life cycle of Echinococcus granulosus?
Humans are incidental intermediate hosts, meaning they can accidentally ingest tapeworm eggs, becoming infected in the process.
What is Hydatid Cyst or Hydatidosis?
Hydatid Cyst or Hydatidosis refers to the larval phase of Echinococcus granulosus, where the tapeworm develops into cysts in the tissues of the intermediate hosts.
What happens when eggs of Echinococcus granulosus are ingested by intermediate hosts?
Upon ingestion, the eggs morph into oncospheres, which migrate to various tissues in the intermediate host. Here, they evolve into metacestodes and form hydatid cysts.
What are brood capsules in the hydatid cyst?
Brood capsules are formed on the inner lining (germinal layer) of the hydatid cyst (metacestode). These capsules contain the next stage of the parasite, the protoscolex.
What is the function of protoscolex in the life cycle of Echinococcus granulosus?
The protoscolex develops within the brood capsules. It ensures the survival of the parasite, allowing it to continue its life cycle, even if the intermediate host dies or the hydatid cyst ruptures.
What happens in secondary Echinococcosis?
In secondary Echinococcosis, protoscoleces spread from the primary site (the hydatid cyst) due to cyst rupture. These protoscoleces proliferate wherever they end up in the host tissue, such as the peritoneum, bronchial tree, pleura, or pelvis.
How do protoscoleces spread to different tissues in secondary Echinococcosis?
Protoscoleces spread to different tissues due to the rupture of the hydatid cyst, which allows them to move into various tissues like the peritoneum, lungs, pleura, or pelvis, where they can proliferate.
What happens to the intermediate host in secondary Echinococcosis?
In secondary Echinococcosis, the intermediate host eventually dies, or it may cough up hydatid material from the lungs.
How do protoscoleces enter the final host (carnivores)?
If tissue or organs of the intermediate host are eaten by the final host (such as dogs, foxes, or hyenas), the protoscoleces enter the intestine of the final host.
What happens once protoscoleces reach the intestine of the final host?
Once in the intestine of the final host, the protoscoleces evolve into scoleces with hooklets on the rostellum (head). They use these hooks to attach to the intestinal mucosa.
What is the final step in the Echinococcus granulosus life cycle?
After attaching to the intestinal mucosa, the protoscoleces develop into adult tapeworms, completing the life cycle of Echinococcus granulosus.
How does Hydatid disease typically present?
Hydatid disease usually presents with symptoms related to the body cavity or organ(s) in which the cysts develop. Symptoms often arise once the cysts have grown to a significant size.
How is Hydatid disease often discovered?
Hydatid disease is frequently discovered by chance, such as when an abdominal mass is found by a parent while bathing a child, or during an ultrasound or chest radiograph conducted for other reasons, such as investigating dyspnoea (shortness of breath) or a persistent cough.
When do neurological symptoms typically develop in Hydatid disease?
Neurological symptoms generally develop fairly late in the disease process, typically when the cysts have reached a significant size and are affecting the nervous system.
What is the focus of the clinical exam for Hydatid disease?
The clinical exam is focused on assessing the overall health of the patient and documenting the extent of the disease’s effects, particularly neurological or respiratory compromise. There are no pathognomonic findings specific to Hydatid disease.
When should Hydatid disease be suspected in a patient?
Hydatid disease should be suspected in patients who live in or have traveled to an endemic area, especially when presenting symptoms suggestive of Hydatid disease.
What are some common abdominal symptoms that suggest Hydatid disease?
In the abdomen, symptoms may include an incidental mass in the right upper quadrant and abdominal pain.
What chest symptoms can suggest Hydatid disease?
Chest symptoms may include cough, productive cough with “grape peels,” cough with fever, and dyspnoea (shortness of breath).
What brain symptoms may indicate Hydatid disease?
Involvement of the brain can lead to focal neurological symptoms, seizures, confusion, and coma.
What is the mainstay of diagnosis for Hydatid disease?
Imaging is the mainstay of diagnosis for Hydatid disease.
What imaging methods are used to diagnose Hydatid disease?
Abdominal Ultrasound: To confirm the location of intra-abdominal cysts.
Chest Radiographs: To confirm lung cysts, their size, location, and number.
CT scan and MRI: Used in very selected cases for further assessment.
What are the three main treatment options for Hydatid disease?
The three main treatment options for Hydatid disease are:
- Surgery alone
- Drugs alone
- Combination of surgery and drugs
Why is Hydatid disease considered a public health problem?
Hydatid disease is a public health problem because it involves the transmission cycle between humans and animals, especially dogs. Addressing pets’ deworming and improving slaughtering practices is crucial in preventing the disease.
What surgical approaches are used for treating Hydatid disease?
Surgical approaches include:
- Open access (laparotomy or thoracotomy)
- Laparoscopy
- In selected cases, thoracoscopy
- Ultrasound-guided needle aspiration (“PAIR” procedure)
What is the “PAIR” procedure for Hydatid disease treatment?
The “PAIR” procedure stands for Percutaneous Aspiration, Injection (of scolicidal), and Re-aspiration. It is a minimally invasive technique for treating Hydatid disease.
What is the medical treatment for Hydatid disease?
The medical treatment typically involves Albendazole taken orally for 3 to 6 months. It is given for 28 days with a 14-day break, repeated as needed depending on the cyst’s response (measured by size reduction).
Can Albendazole be combined with other drugs?
Yes, Albendazole can be combined with Praziquantel. The length of treatment remains the same as with Albendazole alone.
What should be done if there is no reduction in cyst size after 3 months of medical treatment?
If there is no reduction in cyst size after 3 months, or if drug side effects become intolerable, medical treatment should be abandoned.
What monitoring is necessary when using Praziquantel for medical treatment?
Liver function tests should be done monthly when Praziquantel is used as part of the treatment.
What is the rationale for combining surgery and drugs in Hydatid disease treatment?
The combination of surgery and drugs is used to pre-treat the hydatid cysts before surgery:
Albendazole kills the metacestode, stopping brood capsule and protoscolex production.
Praziquantel kills the protoscoleces, rendering the hydatid fluid sterile, reducing the risk of spillage and disease dissemination during surgery.
When should a patient with Hydatid disease be referred to a specialized center?
Patients should be referred to centers with sufficient radiology and surgical experience to manage Hydatid disease. Once the diagnosis is confirmed, medical treatment can be started while coordinating with surgeons to avoid delays.
What is the long-term outcome after surgery for Hydatid disease?
Surgery is curative for Hydatid disease. If there is a recurrence, it is most likely due to re-infection rather than a failure of the surgery.
Why might recurrence of Hydatid disease occur after surgery?
Recurrence is most often caused by re-infection, not by surgical failure. Patients and their families need to understand how re-infection happens to prevent it.
What is important for patients and their families to understand after treatment for Hydatid disease?
Patients and families need to understand how the infection occurs in the first place, so they can take measures to prevent re-infection, such as proper deworming of pets and addressing hygiene practices.
