role of companion animals in emergence and transmission of parasitic zoonoses
DESCRIPTION
Several parasitic infections and infestation are common in developing countries where companion animals (dog and cats) play an important role. The presentations talks about a few important ones .TRANSCRIPT
Role of Companion Animals in emergence and transmission of Parasitic Zoonoses
Dr. M. Senthil Murugan, M.V.Sc Scholar EpidemiologyDr. D.K. Singh, Principal Scientist, Veterinary Public Health
Dr. Bhoj R Singh, Principal Scientist and Head, Division of Epidemiology
Companion animals?
•An animal that someone keeps for company and enjoyment (MacMillan dictionary)
•Dogs, Cats, rodents, birds, Fish and horses
Companion versus Stray dogs As Pets Stray Populations
• Human – Animal bond• Mental ,Physical and
Social well being
• Utility, sporting, assistance dogs – Blind & deaf
• Developing Countries – High Stray dogs population
• Share close relationship with humans
• In India 19 million Stray dogs
Traub, et al., 2005MacPherson et al., 2010
Who are at risk ?Those in need of companion and---.
1. Immuno Compromised individuals- AIDS, Cancer, Organ and Bone marrow transplants, Steroid therapy
2. Children, Geriatrics
3. Pregnant Women
4. Veterinary professionals
5. Animal handler / Researcher
Robertson et al., 2000
Disease in Companion animals
Parasitic Zoonotic Agent Disease in Humans
EchinococosisEcchinococcous
granulosesEchinococcus multilocularis
Cystic echinococcosisAlveolar echinococcosis
Toxoplasmosis Toxoplasma gondii Congenital and Ocular Toxoplasmosis
Toxacariasis Toxacara canis, Toxacara cati
Visceral and Ocular Larval Migrans
Ancylostomiasis Ancylostoma caninumA.ceylanicum
Cutaneous Larval Migrans
Giardiasis Giardia duodenalis GI disturbances
Cryptosporidiosis Cryptosporidum canis,C.felis Rare infection
Leishmaniasis Leishmania donovani Cutaneous and Visceral Leishmaniasis
Dipylidiasis Dipyllidium caninum Children are affected
Human behavior and emergence of parasitic zoonoses
• Growing global population (>6.4 billion) causing:
1. Exploitation of natural environment, e.g. AE
2. Urbanization – Inadequate sanitation and garbage disposal.
3. High percapita garbage – more stray dogs.
4. Breeding sites for vectors e.g. Leishmaniasis in dogs.
5. Inappropriate feeding: Uncooked meat (Smoked & cured) e.g. Toxaplasma cysts. Feeding offals to dogs may lead to Echinoccosis.
6. Poor hygiene – Lower economic strata, so many faeco-oral infections.
Macpherson, 2005
Dogs as Mechanical Carriers•Mechanical reservoir for human
parasites•Host specific human parasites – Ascaris
lumbricoides, Trichuris trichiura, Hymenolepis diminuta and Isospora belli
•Viable Ascarid eggs isolated from 30 % of dog feces in Assam (Traub et al., 2005)
•Fur of dogs – Carry T. gondii to humans (Tenter et al., 2000)
Factors for Emergence of GI Protozoans• Western world & Urbanization
– regular deworming of pets
• Enteric protozoans remains unaffected by anthelminthics
• Intestinal protozoans (Giardia and Cryptosporidium) may be colonizing the niche vacated by T. canis and D. caninum and other helminths killed by anthelmintics.
• Pet ownership
Giardia colonization of GI mucosa
Robertson et al., 2000
Transmission of Giardiasis• Giardia duodenalis - Humans are reservoir
• Zoonotic strains of Assemblage AI, AII and B – from dogs
• Cysts – infective stage, prolonged survival of cysts in environment (Weeks to months)
• Ingestion of food, water or arthropods carrying cysts.
• 10 – 100 cysts sufficient for Direct fecal - oral and water borne transmission
Thurtson et al., 2002
Emergence Giardiasis in Assam• Type A 39 % & B 61% in humans
• Same Genotype in the same village and the same house hold both in Dogs & Humans
• Human isolates - Assemblage A or B and that all found in Dog isolates
• Dog was infected through Coprophagy of human feaces
• Multi-dog in household are more prone for infection
• Dogs infected with own host adapted Assemblage C & D, and also with Zoonotic genotypes A and BTraub et al., 2004
Minimal zoonotic risk & Cryptosporidiosis• C. canis and C. felis oocysts
are common in feces dogs and Cats
• Human cases are associated with C. hominis and C. parvum
• Molecular epidemiologic studies proves low risk of zoonotic transmission
• Rarely immunocompromised pet owners may acquire the infection from dogs.Forster et al., 2010
Lifecycle of Cryptosporidium sp
Transmission of Toxoplasmosis• Toxoplasma gondii from
Cats• Highly resistant oocytes• Asexual stages in
intermediate host (IMH) – all vertebrates
• In Pregnancy – Vertical transmission
• Cats excrete oocysts for 20 days of infection
• Reinfection infection after 6 yrs, however under immunosupression cats starts to excrete oocysts
Tenter et al., 2000
Toxoplasmosis - Transmission• Tachyzoites – in milk of
IMH (Sheep, Goat and Cows)
• Tissue cysts or Tachyzoites – in meat or offal
• In unpasteurized milk• In raw uncooked meat –
Pig, Sheep• Oocyst in environment
and water (Dubey, 2004)
• Oocysts in Vegetables put vegetarians on risk
Tissue cyst (Tachyzoites)
Tissue breakdown periodically(Bradyzoite)
Reinfect host cellsTenter et al., 2000
Intermediate Host (IMH)
Toxoplasmosis in India
Species(1990 – 2000)
Seropreva-lence (%)
Reference
Women of Child bearing age
2226
Malhotra et al., 1991
Pal et al., 2011
Cattle and buffaloes 43Mathur et al.,
1991
Domestic Fowl 40 Devda et al., 1998
Sheep 23 Dubey et al., 1993
Goat 68 Dubey et al., 1993Tenter et al., 2000
T. gondii Oocyst Survival
Temperature
Survival period
1 to 4 o C 3 weeks-1 to – 8 o C 1 week
-12 o C Killed67 o C Killed
• Relatively resistant to changes in temperature
• In Soil > 18 months• In IMH 10 sporulated oocysts are
sufficient for infection
• For Cats 100 oocysts are required for infection
• Varying excystation (Dubey,1996) • Tissue cyst are resistant to
Digestive enzymes & also• Resistant to chemical and
disinfectants (Dubey,1996) Tenter et al., 2000
Emergence of Toxoplasmosis•One third of world population is exposed
•Seroprevalence is high –in meat consumers (mutton, beef, pork), in Pregnant women (Pal,2011)
•Consumption of uncooked meat, smoked , cured meat enhances risk in IMH
17
Transmission of Ancylostomiasis• Ancylostoma braziliense - CLM
• A. caninum- eosinophilic enteritis
• A. ceylanicum – CLM, Anemia
• Tropical Humid Climate a major risk factor.
• Eggs remain viable in moist, shaded and sandy soil
• Puppies may got infection through transmammary route (mother’s milk)
• In Humans – percutaneous penetration by the parasite
Egg pass in feces
Hatch in conducive environment L2 Larvae
Percutaneous entry – Lungs – Cough up - intestine
17
Re -Emergence of Ancylostoma ceylanicum• Ist discovered in 1913 - 9.3% prisoners in Calcutta
• until 1960 erroneously referred with A. braziliense
• Resurfaced 50 years later in South East Asia
Bangkok, Loas, Thailand, Malaysia and Indonesia
• Risk for communities with A. ceylanicum is endemic in dogs.
• 62 % prevalence in India in stray dog and cats (Traub
2007)
• Percutaneous infection / ingestion leads to Eosinophilic enteritis
Bowman et al., 2010
Geographical Distribution A. ceylanicum
Country
Human Pets
Bangkok
3.4% 58%
Laos 17.6 % 77.8 %
Malaysia
9.1 % 74%
Bowman et al., 2010
Cystic Echinococcosis - Transmission• Echinococcus granulosus – G1- G10
strain
• Unilocular cyst - all organs
• Humans: G1 Strain, Sheep – dog cycle
• Urban-cycle – feeding raw offals to dogs
• Direct contact – fecal oral contact of eggs
• Dogs Carry pathogen on - Hairs, muzzle, paws
• May be transmitted indirectly – through contaminated food and water and through
• Flies and other arthropods - Cockroaches
Pedro Moro et al., 2008
Alveolar Echinoccosis - Transmission• Echinococcus multilocularis • Sylvatic cycle– Fox• Dogs acquire infection by
ingestion of Wild Rodents, lagomorphs (IMH)
• Dogs pass the egg in feaces.• Cats are less susceptible
than canids (Kapel, et al., 2006)
Pedro Moro et al., 2008
Emergence of EchinoccosisCountry Early 1950 Late 1990 / 2000Bulgaria 6.5/Lakh population 15.8 / lakh population
Kazakhstan 1.4/lakh population 3.6 / lakh populationChina - 8.7/ lakh population
Argentina - 14900 / lakh population
Brazil - 5000/ lakh populationUruguay - 12.4/ lakh population
Causes of reemergence:•Political instability•Administrative irregularities•Economic changes• Reduced Funds for control
•Control measures are not followed•AE – dog ownership•Urban foci – feeding offals
Eckert, 2009
Transmission of Toxacariasis• Toxacara canis, T. cati are transmitted
transplacentally, Transmammary to puppies and kittens.
• Several forms: Visceral, neural, ocular and asymptomatic
• Children acquire infection through ingestion of contaminated soil.
• Infection on consuming ▫ raw liver food animals
▫Uncooked vegetables
• Direct Contact with embryonated eggs on dog hair
Alice Lee et al., 2010
Toxacara eggs survive in soil• At optimal environment,
eggs survive in soil for 2 – 4 yrs
• In winter for 6 – 12 months
• Cats bury their feces in soil
• Egg contamination in play grounds, parks, garden (Manini et al., 2012)
Sudhakar et al., 2013
Toxacara eggs in Barielly
Dog hair in Toxacara Transmission?• Dogs harbour eggs of parasite in
fur• Humans : Ingestion of
embryonated eggs - picked form coat of dog
• Eggs on Hairs in dorsal > perianal area
• On hair: Higher densities of eggs than in soil.
• Puppies are hugged and handled most – hence higher the risk of transmission.
Wolfe & Wright , 2003
Rolling of Dogs
Potential Puppies !!!Pups Adults
• Eggs in hair: 95%
• Worm infestation 80 %
• Strong Positive correlation in
Worms and eggs in hair
• Contamination their own fur and
litter mates
• Embryonated egg 0.31 % (3 times)
• Shorter hair, better heat transfer –
better development of egg
• Eggs in hair : 56%• Worm infestation 22.5%• No correlation in no. of worms
and eggs in coat
• Picked by rolling in environment contaminated with eggs
• Embryonated egg 0.12%
• Adult hairs – non conducive for embryonation of egg
Roddie et al., 2008
LeishmaniasisTransmission• Leishmania infantum – ZVL
• L. tropica – CL
• Vector: Sand fly/ Phlebotomine sp
• Major urban reservoir: Dogs
• Infection in dogs proceeds occurrence in humans in particular geographical area Wendel Coura - Vital et al., 2013
Life cycle of Leishmania Sp
Emergence of Leishmania in RajastanSpecies Percent
PrevalencePet Dogs 24
Street dogs 21Humans 68.04
• Cutaneous leishmaniasis – Leishamania tropica
• Dogs -Cutaneous lesions in face, nostril, eyes and extremities
• Humans – chronic non healing ulcers
• Infected street dogs – transmission to humans
• Increased humidity and near Rajasthan canal – breeding for sand flies
• Presence of infected dogs in corresponding area – increased prevalence in humans
Sharma. et al., 2003
Transmission of Dipylidiasis• Dipylidium caninum –
Cestode of Dogs
• Humans - accidental host
• Flea vector - Cysteicercoid
• Ctenocephalides canis, C. felis
• Ingestion of fleas – Children -
Develop in to adult worms
Life cycle of Dipylidium Caninum
Other Emerging Parasitic ZoonosesDisease Etiology Vector / source Country
BabesiosisBabesia canis, B.
conrade Ixodes ricinus USA
Chagas Disease (American
trypanosomiasis) Trypanosoma cruzi Triatomine bugs USA
Canine Heart worm Dirofilaria immitis Ctenocephalides canis USA
Murine typhus Rickettsia typhi Ctenocephalides felis USA
Canine Heart wormAcanthochelionema
reconditum Ctenocephalides canis USA
Paragonimiasis (Lung Fluke)
Paragonimus westermanii Crabs, cray fish China
Clonorchiasis Clonorchis sinensis Fish, shrimp China
Trichnosis Trichinella spiralis Dog meat China
Traversa et al., 2013
Other Pet animal & Parasitic zoonoses
Species Zoonotic parasitic diseaseHorses Trichuriasis, HydatidosisRabbits Cheyletiella parasitivorax (Mite)
Rats Hymenolepis diminuta (Cestode)Rodents Trixacarus caviae (Acarid)Snakes Pentostomiasis (Armillifer armillatus)
FishClonorchiasis, Diphyllobothriosis,
Gnathostomiasis
Persistence of parasitic zoonoses in India
• 98 % of the dogs are not dewormed or vaccinated in India (Traub et al., 2002)
• Poor hygiene
• Over crowding urban areas
• Disease burden is not known
• Stray animals close contact with humans
• Surveillance and control of Canine zoonoses – low prioritized
Robertson et al., 2000
Control of Parasitic Zoonoses• Veterinarians - Education of owners
• Regular deworming and ectoparasite control
• ABC – Stray animals
• “Do not feed cysts to dogs”
• Foreign countries ‘Scoop laws’
• Urban sanitation
• Changing eating habits – washing and cooking
• Safe drinking water
• Personal hygiene – Hand washingMacpherson, 2005