Hydatidosis is a zoonotic infection caused by cestode of the genus echinococcus. The definitive hosts include dogs, wild dogs, foxes etc. in which adult worms are present in the intestines.
More than 50,000 worms may inhabit the duodenum and upper jejunum of infected dogs and individual worms are said to disrupt the intestinal mucosa, such massive infection are well tolerated by the definitive host with no clinical signs. Intermediate hosts include sheep, pigs, goats, cattle and humans in which metacestode develop which are referred to as hydatid cysts.
Human beings especially children, acquire the diseases by ingestion of echinococcus eggs which occurs by hand to mouth transfer of eggs after contact with infected dogs but may also result from ingestion of food water, soil or fomites contaminated by infected dog faeces.
Etiology
Four species of echinococcus are known to cause diseases in human beings E.granulosus, E.multilocularis, E.vogeli and E.oligasthus. Both E.granulosus, E.multilocularis tend to establish systematic cycles when suitable prey predator relationships exit in the wild life population.
Echinococcus granulosus
It is the widespread species causing cystic hydatid disease. The eggs when ingested hatch and release oncosphere. The larva grows slowly and infrequently and exceeds more than a few centimeters in diameter in slaughter sheep and cattle.
Cyst commonly develops in the liver 20%, brain1%, peritoneal cavity 8%, Kidney-3%, bone marrow and other organs 3%.The most causes an anaphylactic reaction that may be fatal.
EPIDEMIOLOGY
1. It is spread all over the world, the mediteranean area, Middle East. Indian subcontient, Africa, Australia and Central America.
2. Depends largely on dissemination of eggs by tapeworms carrier rural dogs and stray dogs.
3. Inappropriate standard of meat inspection or practice of private slaughtering without mandatory meat inspection favours distribution.
4. Pattern of transmission is dependent on the genetic variant of E.granulosus, prevailing in an endemic area.
5. It is a epidemiological relevance that E.granulosus, has a number of genetic variations adapted either in sheep or cattle or horse or pigs (usually designated as dog-sheeep,dog-cattle, dog- horse strains etc), individual strains may differ in features of morphology, biology(fertile/sterile cyst ratio), antigenic composition and infectivity to man.
6. Older animals are less susceptible to infection and develop sterile cysts most frequently.
7. Eggs may survive over a year in the environment, but perish rapidly if exposed to high temperature.
Control Of Hydatidosis
1.Health education and personal Hygiene
2. Limiting the population of stray dogs regimented antihelminthic. medication (Praziquinatal during prepatent period every 6 months of potential infection on more practically every 3 months).
3. Prohibition of the feeding of uncooked offal to dogs and cats.
4. Efficient meat inspection procedures with effective disposal of rejected meat and offals.
5. Avoid eating unwashed fruits and vegetables in are of endemicity.
6. Foodstuffs can be rendered safe by heating at 45*c for 3 hours. Eggs survive storage in house hold deep freezer but lose infectivity after 3 days of freezing at -80 degrees c.
Adopting these measures will not only control the hydatidosis among our beloved pets but also among us, the prestigious pet owners.