animal associated parasitic infection

8/13/2019 Animal Associated Parasitic Infection

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ANIMAL ASSOCIATED PARASITIC INFECTIONS

Introduction

A zoonosis (plural: ses) is any disease or infection that is naturally transmissible directly or indirectly from

vertebrate animals, wild or domestic, to humans. Animals thus play an essential role in maintaining zoonotic

infections in nature. Zoonoses may be bacterial, viral, or parasitic in origin. Zoonotic diseases are considered as

public health problem, as well as major problem that prevent the efficient production of food and otherproducts of animal origin. Approximately 60% of all human pathogens are zoonotic and about 75% of emerging

infectious diseases have an animal origin.

Zoonotic parasitoses (singular: sis) are those human infections caused by zoonotic parasites. These parasites

can be from one of the four classes namely: protozoa, nematodes, cestodes, and trematodes. In most cases,

parasitic infections have worldwide distribution; however, some cases are localized to certain geographical

areas. Intestinal parasitoses are the most common parasitic infections.

ROUTE OF TRANSMISSION

Methods of parasite transmission can be through insect bites, handling animal litter/ feces, handling raw meat/fish, contaminated fruits and vegetables, contaminated water, contact with an infected person etc.

However, broad categories of Zoonotic parasite transmission to humans are:

I. Vectorborne (insects)II. Water borne

III. Feco-oral ContaminationIV. Infected Meat

VECTOR-BORNE PARASITES

A vector is an agent which transfers a parasite from one host to another. Typical parasite vectors are fleas,

ticks, mites, mosquitoes, flies, and other insects. People become infected when a vector picks up the parasite

from an infected animal and infects human. Many parasites that are carried by vectors are often found in the

blood of humans and animals. Important vector-borne parasitoses are:

a) Chagasdisease (American trypanasomiasis)Distribution: central and South America

Parasite: Trypanasoma cruzi

Host: animals(raccoons, opossums, and foxes)bugshumans.Vector: Kissing Bug(triemtaris)

Spread: The bug bites human then defecates next to the wound. Rubbing bite wound spreads parasite into the

wound.

Presentation: heart disease, malformation of the intestines and CNS (in children)

Diagnosis: Giemsa stained bloodfilm microscopy, serology (IF, ELISA)

Control: personal protection, blood donor screening, better housing, sythentic pyrethroids


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b) Babesiasis/ BabesiosisParasite: Babesia spp. (intracellular in RBC)

Host: Animal (cattle) and human

Spread: Via infected ticks

Presentation: Fever with anemia, hyperbillirubinuria, hemoglobinuria

Diagnosis: Giemsa stained thick bloodfilm

Control: Vector control, early and prompt management

c) LeishmaniasisDistribution: Worldwide, specie specific geographical location

Parasite: Leishimania spp (L. tropica, L. mexicana, L. viannia braziliensis, L. donovanni)-tissue

Host: Dogs, cats, swine

Spread: Through the bite of an infected Sandfly (phlebotomus, lutzomyia)

Presentation: Cutaneous (oriental sore), Mucocutaneous (espundia) and Visceral (kala-azar)

Diagnosis: Microscopy of Giemsa-stained tissue or fluid sample.

Control: Early diagnosis and prompt treatment; Vector control and health education

WATERBORNE PARASITES

Waterborne parasites Spread when humans come into contact with water that has been contaminated by an

infected animal. Common waterborne parasitoses include Giardiasis and Cryptosporidiosis

a) Giardiasis (Beaver fever)Distribution: worldwide

Parasite: Giardia spp:G. lamblia(mammals such as humans and livestock), G. agilis(amphibians), G. muris

(rodents), G. ardeaeand G. psittaci(birds), and G. microti(muskrats and voles)

Host: Rodents, Birds, Aquatic Animals (e.g Beaver & Muskrat) and Human

Spread: Ingestion of water contaminated (with cyst) by infected human or animal and feco-oral.

Presentation: Explosive, watery, greasy, malordorous, non bloody diarrhea.

Diagnosis: Stool or duodenal aspirate (O & P) examination, stoolantigenassay (ELISA, IFA), String test

Control: Boiling and filtering drinking water, personal hygiene.

b) CryptosporidiosisDistribution: Worldwide

Parasite: Cryptosporidium spp. (C. parvum, C. hominis,C. canis, C. felis, C. meleagridis, and C. muris)

Host: Animal (cattle and sheep) and humans

Spread: Ingestion of water (swimming) contaminated with infective cyst.

Presentation: Chronic watery diarrhea (esp. in immunocompromised)

Diagnosis: Stool (O & P) examination using acid-fast staining, stoolantigenassay (ELISA, IFA, PCR)

Control: Boiling and filtering drinking water, personal hygiene.

FECAL-ORAL TRANSMISSION

This is the most common way through which people become infected with zoonotic parasites. Parasites are

spread to humans when they ingest the infective organism from the feces of an infected animal. These types of

parasites generally live in the intestinal tract. Examples are Hookworms, Roundworms, Hydatid Disease,

Toxoplasmosis etc.
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a) Ancylostomiasis (hookworm)Distribution: Worldwide

Parasite: Ancylostoma spp. (A. caninum, A. braziliense, and A. tubaeforme.)

Host: Cats, Dogs and Humans

Spread: Ingestion of or skin penetration by infective larvae, or from larvae passed in milk

Presentation: Cutaneous larva migrants, anaemia, abdominal discomfort (eosinophillic entritis)

Diagnosis: Stool O & P examination, serum examination, skin test.

Control: Personal and environmental hygiene, pets deworming, wearing shoes by children

b) Ascriasis (roundworm)Distribution: Worldwide

Parasite: Ascarids (Toxocara canis, T. cati), raccoonsascrids (Baylisascaris procyonis)

Host: Dogs and cats

Spread: Ingestion of infective eggs in faeces of infected animal

Presentation: Visceral larva migrans (affecting the eyes, brain, liver, and lung,)

Diagnosis: Stool O & P examination, tissue histology, serology

Control: Personal and environmental hygiene, pets deworming

c) ToxoplasmosisDistribution: WorldwideParasite: Toxoplasma spp. (T. gondii)

Host: Cats, Mammals, Birds

Spread: Ingestion of oocyst present in cat faeces, undercooked meat, congenitally.

Presentation: Fever, lyphadenopathy, neonatal blindness, seizures, (severe cases in immunocompromised)

Diagnosis: Microscopy of tissue specimen, serology

Control: Sanitary disposal of pet feces, pets deworming

d) Hydatid Disease (Extra-intestinal Tapeworm Infection)Distribution: Worldwide

Parasite: Echinococcus granulosus, E. multilocularis

Host: Dogs and sheep

Spread: Ingestion of fertilized eggs present in contaminated animal faeces, undercooked meat

Presentation: Hydatid cyst pressure symptoms (in liver, kidney and brain), allergic reactions

Diagnosis: CAT scanning, tissue biopsy and microscopy, serology

Control: Sanitary disposal of pet feces, pets deworming

CONTAMINATED MEAT

Meat can be contaminated with harmful bacteria and can also contain parasitic cysts which may infect

humans. Common Parasites found in meat are: Toxoplasma, Trichinella , Taenia , Gnathostoma

a) TrichinosisDistribution: Worldwide

Parasite: Trichinella spiralis

Host: Pig and Human

Spread: Ingestion of cyst in undercooked pork

Presentation: Abdominal pain, diarrhoea, fever and muscle ache.

Diagnosis: Muscle biopsy (coiled encysted larva), serology

Control: Better animal management and slaughter protocol, freezing or cooking meat well!


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b) GnathostomosisDistribution: East and Southeast Asia

Parasite: Gnathostoma spinigerum

Host: Rat and fish

Spread: Ingestion of uncooked fish

Presentation: Cutaneous/ migratory lesions

Diagnosis: Skin test, Tissue biopsy

Taeniasis

c) Taeniasis (Pork Tapeworm)Distribution: Worldwide

Parasites:Taenia solium

Host: Pigs and human

Spread: Ingestion of undercooked pork infected with larvae

Presentation: Neurocysticercosis (seizures, meningitis, hydrocephalus, and focal deficits).

Diagnosis: Demonstration of proglottids and/or eggs in a fecal sample

d) Taeniasis (Beef Tapeworm)Distribution: Worldwide

Parasites:Taenia saginata

Host: Cattle and human

Spread: Ingestion of undercooked beef infected with larvae

Presentation: Malnutrition and weight loss

Diagnosis: Identifying gravid proglottids and/or eggs in faeces.

e) Taeniasis (Fish Tapeworm)Distribution: Worldwide

Parasites:Diphyllobothrium latum

Host: Freshwater fish (trout, salmon, pike)

Spread: Ingesting larvae in raw/undercooked freshwater fish

Presentation: Abdominal discomfort, megaloblastic anaemia (Vit. B12deficiency)

Diagnosis: Identification of eggs in the feces.

MBBS 300L lecture Note

Prepared by Dr M.I.Getso 7

Dept of Medical Microbiology and Parasitology, BUK (May 2013).

References

1. Antti Lavikainen. Human medical view on zoonotic parasites (October, 2010)http://www.actavetscand.com/content/52/S1/S4 2. Jawetz, Melnick, & Adelberg's Medical Microbiology, 24th Edition. USA: McGraw-Hill 2007; chapter 463. Louis M. Weiss. Zoonotic Parasitic Diseases: Emerging issues and Problems. Int J Parasitol. 2008 September; 38(11): 12091210.4. Parasite Cleanse Resource Center. Animal Parasites: How they can affect humans.( 2009). http://www.parasite-cleanse.com/animal-parasites5. Richard A.H. and Pamela A.C. Lippincotts Illustrated Review: Microbiology. USA: Lippincott and Wilkins 2001; 279-896. Zoonotic Parasites (2010).www. PEER.tamu.edu7. Frances TF. A manual of laboratory and diagnostic test, 7thed. USA: Lippincott and Wilkins 2003; Ch.7 Diagnosis of parasitic diseases
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