Epidemiology of communicable disese. parasitic infestation.

1. HYDATID DISEASE
PRESENTED BY : Sanjeeta Ghimire

2. Echinococcosis:
It is a parasitic infestation caused by tapeworm of the genus Echinococcus which are responsible for causing this
disease in human.
Types of echinococcosis are :
1. Cystic echinococcosis(CE):
• It is also known as hydatid disease or hydatidosis.
• It is caused by infection with a species complex centered on Echinococcus granulosus.
2. Alveolar echinococcosis(AE):
• It is caused by infection with E. multilocularis.
3. Neotropical echinococcosis:
• It is a polycystic caused by infection with E. vogeli.
4. Unicystic echinococcosis:
• It is caused by E. oligarthrus.
INTRODUCTION

3. HISTORY:
• The presence of hydatid cysts in both animals and humans was well-known in ancient times
too.
• In 1st and 2nd century, it was described by Arataeus and Galen & in the 4th century, in the
works of Hippocrates, respectively.
• In 17th century, the parasitic nature of these cysts were recognized by Francesco Redi.
• In 1766, German Pierre Simon Pallas formulated hypothesis that hydatid cysts were larval
stages of tapeworm.
• Later in 1853, Carl von Siebold demonstrated that cysts from sheep lead to adult tapeworm in
dogs.
• After a decade, Bernhard Naunyn recognized that the adult tapeworms directly develop from
hydatid cysts.

4. PROBLEM STATEMENT:
• Hydatid diseases occurs worldwide.
• Mostly found in sheep-raising countries like Australia, New Zealand, Tasmania,
Middle East countries, Turkey Greece, Cyprus, Latin America, etc.
• More than 1 million people are affected with cystic and alveolar echinococcosis
at any one time, worldwide.
• For cystic echinococcosis, there is average of 2.2% post-operative death rate for
surgical patients.
• 6.5% cases relapse after interventions, causing prolonged recovery.
• In 2015, WHO Food Borne Epidemiology Reference Group estimated 19,300
deaths and around 871,000 DALYs(Disability Adjusted Life Years), Globally.

5. EPIDEMIOLOGICAL DETERMINANTS:
AGENT FACTORS:
⮚Echinococcus species.
⮚Hydatid disease is caused by infection with the larval
stage of Echinococcus granulosus (~2–7 mm long
tapeworm)
⮚Alveolar echinococcosis (AE) disease is caused by
infection with the larval stage of Echinococcus
multilocularis (~1–4 mm long tapeworm).

6. HOST FACTORS:
Hydatid disease
✔Definitive host : Dogs
✔Intermediate host: sheep, cattles, goats and pigs.
✔Human is the accidental intermediate host of this disease.
✔This disease is associated with occupations like Shepherds, Shoe-makers, etc.
✔Movement of population from endemic areas and non-endemic areas can also
result in the spread of infection.
Alveolar echinococcosis disease
✔Definitive host: Foxes, coyotes and dogs
✔Intermediate host: Small rodents.

7. MODE OF TRANSMISSION
• It is not transmitted from person-to-person.
• Faecal-oral route.
• Human infection occurs by ingestion of the eggs of
Echinococcus through foods, unwashed vegetables or
contaminated water from definitive host (dogs).

8. LIFE CYCLE

9. INCUBATION PERIOD:
✔ Variable from months to years.
✔ It depends upon the number, location and growth of cysts.

10. CLINICAL FEATURES:
• Human infections with Echinococcus granulosus often remain asymptomatic for years until the hydatid
cysts grow large enough to cause symptoms in the affected organs like liver and lungs.
• It may also affect the bones, kidneys, spleen, muscles and central nervous system.
• If the liver gets affected; discomfort, abdominal pain, nausea and vomiting occurs.
• If the lungs gets affected; chronic cough, shortness of breath and chest pain occurs commonly.
• Non-specific signs includes; anorexia, weight loss and weakness.
Organs Distribution of hydatid cysts
(in percentage)
Liver 70%
Lungs 10-20%
Brain 5%
Bones 1%
Other organs (Kidney, spleen, pelvic organs,
muscles)
10%

11. DIAGNOSIS
• Ultrasonography
• X-ray
• MRI and CAT scan.
• Serological tests (indirect immunoflourescent test, ELISA)
• The intra-dermal (Casoni) test.
▪ Expensive and complicated to treat.
▪ Prolonged recovery.
▪ Percutaneous treatment of the hydatid cysts with the PAIR (Puncture, Aspiration,
Injection, Re-aspiration) technique
▪ Surgery
▪ Anti-infective drug treatment
▪ “watch and wait”
TREATMENT
Fig: MRI of hydatid cyst in brain

12. PREVENTION AND CONTROL
⮚Cystic echinococcosis is controlled by preventing transmission of the parasite.
⮚ Prevention measures include limiting the areas where dogs are allowed and preventing
animals from consuming meat infected with cysts.
⮚Ensure dogs are kept away from the areas where animals are slaughtered and are not allowed
to scavenge on carcasses.
✔ Prevent dogs from eating uncooked offal.
✔ Dispose of infected offal by deep burial or burning to prevent it from being consumed by
dogs or other canines.
✔ Reduce dog populations on farms to the occupational need for them.
✔ Seek advice from your veterinarian about effective treatment to prevent infection in
working, pet or visiting dogs. This is particularly important for dogs in rural areas or those
that may have contact with wildlife or feral animals.
⮚Restrict home slaughter of sheep and other livestock.
⮚Do not consume any food or water that may have been contaminated by fecal matter from
dogs.

13. Cont.
⮚ Wash your hands with soap and warm water after handling dogs, and before handling food.
⮚Teach children the importance of washing hands to prevent infection.
⮚Periodic deworming of dogs with praziquantel (at least 4 times per year), improved hygiene in the
slaughtering of livestock (including the proper destruction of infected offal), and public education
campaigns have been found to lower and, in high-income countries, prevent transmission and alleviate
the burden of human disease.
⮚Vaccination of sheep with an E. granulosus recombinant antigen (EG95) offers encouraging prospects
for prevention and control.
⮚A programs combining vaccination of lambs, deworming of dogs and culling of older sheep could lead
to elimination of cystic echinococcosis disease in humans in less than 10 years.

14. WHO strategy for strengthening
echinoccosis prevention and control:
▪ Informal Working Groups on Echinococcosis were founded in 1985 under the
auspices of the WHO.
▪ In 1995, the WHO modified the structure of the groups and transformed them into
a single group, the WHO Informal Working Group on Echinococcosis (WHO-IWGE).
▪ The mission of the WHO-IWGE is to strengthen prevention and control of
echinococcosis through effective collaboration with strategic partners and relevant
sectors.
▪ The WHO-IWGE is in the process of reviewing the diagnosis and associated clinical
management of echinococcosis and elaborating technical manuals with practical
applicability.

15. References:
• www.who.int
• www.cdc.gov
• web.standford.edu
• PARK’S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICINE (25TH EDITION)

16. THANK YOU !!!