Zoonotic Parasites

Zoonosis

any disease or parasite that is transmissible from animals to humans.

It is not the role of the DVM/Technician to diagnose or treat in humans

True

Parasites of Public Heath Importance

Protozoans

Toxoplasma gondii (Toxoplasmosis)

Cryptosporidium parvum (Cryptosporidiosis)

Parasites of Public Heath Importance

Trematodes

Schistosomes of Wild Migratory Birds (Swimmer’s itch)

Parasites of Public Heath Importance

Cestodes

Taenia saginata (Beef tapeworm)

Taenia solium (Pork tapeworm)

Echinococcus granulosus, E. multiocularis  (Unilocular  & Multilocular Hydatid disease)

Dipylidium caninum (Human Dipylidiasis)

Hymenolepis nana, H. diminuta (Hymenolepiasis)

Diphyllobothriumlatum (Diphyllobothriasis)

Parasites of Public Heath Importance

Nematodes

Toxocara canis, T. cati (Visceral or Ocular Larva Migrans)

Baylisascaris procyonis (Neural Larva Migrans)

Ancylostoma spp. (Cutaneous Larva Migrans)

Strongyloides stercoralis (Strongyloidiasis)

Trichinella spiralis (Trichinosis)

Parasites of Public Heath Importance

Arthropods

Sarcoptes scabei canis (Canine scabies)

Toxoplasma gondii

• Human disease: Toxoplasmosis

• Route of infection: Congenitally(unborn babies) or acquired by ingesting sporulated oocysts

• Symptoms:

  • Congenital- abortion if early in pregnancy, if late in pregnancy the central nervous system becomes infected and a variety of neurologic abnormalities may result

  • Acquired-mild fever and slight enlargement of the lymph nodes, may also show signs of malaise, lymphocytosis, and myocarditis

• Treatment: No completely satisfactory treatment, some effectiveness seen with pyrimethamine and triple sulfa drugs combined for the ocular toxoplasmosis

• Prevention:

  • Don’t handle feces if pregnant

  • Wash hands after handling cat and before eating

  • Litter boxes should not be near kitchen

  • Wear gloves when gardening

  • Cover children's sandbox

  • Prevent outdoor cats from eating rodents

  • Don’t eat undercooked meat

Cryptosporidium Parvum

• Human disease: Cryptosporidiosis

• Route of infection: Ingestion of infective oocysts in calf feces through contaminated drinking water

• Symptoms: Painful, watery diarrhea can last 3-7 days or weeks to months

• Diagnosis: Fecal flotation, acid-fast stains, ELISA test or indirect fluorescent antibody (IFA)testing

• Treatment: Symptomatically, give fluids if dehydrated, clinical improvement has been seen in patients treated with dialyzable leukocyte extract from calves immunized with Cryptosporidium spp.

• Prevention:

  • Good sanitation and hygiene when handling calves

  • Immune compromised individuals should wash their hands after handling animals

  • Avoid contact with animal feces

• Important note:   agents and processes used to sanitize public drinking water have little effect on Cryptosporidium species

• Humans develop natural immunity to it after exposure

Schistosomes of Wild Migratory Birds

• Human disease: Schistosome Cercarial Dermatitis or Swimmer’s Itch

• Route of infection: Penetration of cercariae into the skin while swimming or wading in lakes, ponds and rivers. Repeated exposure causes more severe symptoms.

• Symptoms: Areas of redness at entry point, then papules and severe pruritis, severe cases, fever, nausea, sleepless nights. Symptoms typically disappear in about a week.

• Diagnosis: Pruritic lesions and history of swimming in infested waters

• Treatment: Refer to physician or dermatologist, antihistamines and topical steroids

• Prevention:

  • Public health warnings in areas of water

  • Protective waterproof clothing for workers

  • Repellents (benzyl benzoate, dibutylphthalate

  • Molluscicides (snail killing compounds) can have adverse effects on plants and other animals in the environment

• Humans are a dead end host

Taenia saginata

• Human disease: Beef Tapeworm

• Route of infection: Ingesting raw or undercooked beef infected with cysticercus

• Symptoms: Diarrhea, constipation, and cramps

• Diagnosis: Gravid proglottids seen in feces or perianal swabs to detect eggs

• Treatment: Praziquantel or niclosamide

• Prevention:

  • Educate on personal hygiene practices

  • Thorough meat inspection

  • Avoid undercooked meat

Taenia solium

• Human disease: Pork Tapeworm

• Route of infection: Ingesting raw or undercooked meat of pigs containing the cysticercus or larval (metacestode) stage; can infect the intestine or subcutaneous sites within the brain or eye.

• Symptoms: Intestinal-Diarrhea, constipation, and cramps, Neurologic-pain, paralysis, epileptic seizures, Ocular-blindness

• Diagnosis: Gravid proglottids seen in feces or radiographic imaging like CT/MRI to reveal presence in the brain and other sites

• Treatment: Praziquantel or surgical removal of lesion

• Prevention:

  • Educate on personal hygiene practices

  • Thorough meat inspection

  • Avoid undercooked meat

Echinococcus granulosus
Echinococcus multiocularis

• Human disease: Unilocular (E. granulosus) and Multilocular (E.multiocularis) Hydatid Disease

• Route of infection: Ingestion of eggs from Echinococcus spp.

• Symptoms: Depends on site where organism develops; liver, lungs, kidney, spleen, bone, and brain. Neurologic symptoms, pain, paralysis and epileptic seizures

• Diagnosis: Histological examination of tissue or radiographic imaging CT/MRI

• Treatment: Surgical removal; treatment with mebendazole has shown varied success, although albendazole has been more promising

• Prevention:

  • Hand washing especially for children

  • Dogs should not be fed raw livestock viscera or eat wild rodents

• Suspected cases in dogs and cats must be reported to state and public health officials and CDC

Dipylidium caninum

• Human disease: Human Dipylidiasis

• Route of infection: Ingestion of flea containing cysticercoids of the tapeworm commonly in dogs and cats

• Symptoms: Asymptomatic, diarrhea, abdominal pain, and anal pruritis, possible mild eosinophilia.

• Diagnosis: Proglottids in the feces

• Treatment: Praziquantel or Niclosamide

• Prevention: Flea prevention on dogs and cats

• Children are more susceptible

Hymenolepis nana (dwarf tapeworm)
Hymenolepis diminuta (rat tapeworm)

• Human disease: Hymenolepiasis

• Route of infection: Ingestion of insects(rat fleas, mealworms, cockroaches) containing cysticercoids of these tapeworms.

• Symptoms: Large infestations cause necrosis & destruction of the intestinal epithelium; light infestations can cause loose bowel movements or frank diarrhea with mucus, persistent abdominal pain, pruritic anus, headaches, dizziness, sleep and behavior disturbances and moderate eosinophilia

• Diagnosis: Eggs in fecal flotation

• Treatment: Praziquantel

• Prevention: Personal hygiene

• Common in children under 3, can be passed human to human, referred to as hand-to-mouth parasites

Diphyllobothrium latum

• Human disease: Diphyllobothriasis

• Route of infection: Eating raw or undercooked fresh water fish  or via homeopathic treatment using infected fish as a poultice on a wound(Sparganum/Plerocercoid stage)

• Symptoms: Intestinal infections-asymptomatic to abdominal pain, bloating, diarrhea, allergic reactions, hunger pains, loss of appetite, or increased appetite, and rarely intestinal obstruction or intussusception. Anemia due to loss of vitamin B 12.

• Wound infections-(Sparganum)severe inflammatory reaction and fibrosis of tissues, urticaria, painful edema, irregular nodules

• Diagnosis: Eggs in fecal flotation or proglottids in feces

• Treatment: Praziquantel, but for Sparganum infection surgical removal

• Prevention:

  • Proper cooking of freshwater fish

  • Freezing fish at minus 10 degrees Celsius

  • Brining and smoking fish eliminates

  • Discourage application of raw fish poultice

  • Sushi anyone!!!!????

Toxocara canis
Toxocara cati

• Human disease: Visceral Larva Migrans(VLM) and Ocular Larva Migrans(OLM)

• Route of infection: Ingestion of eggs from the soil or on contaminated hands or objects VLM-larvae migrate through liver, lungs, heart, and brain; OLV-invade the eye

• Symptoms: Asymptomatic if only a few larvae ingested

• VLM-fever, leukocytosis, persistent eosinophilia , hypergammaglobulinemia, and hepatomegaly; pulmonary involvement causes bronchiolitis, asthma, or pneumonitis. Fatalities result when myocardium or CNS involved

• OLV- ocular disease, faulty vision, blindness

• Diagnosis: VLM- lesions and larvae found on biopsy of tissue or serum samples sent to CDC

• OLM-larvae observed on ocular exam

• Treatment: No proven treatment is available, suggested drugs of choice include: mebendazole and diethylcarbamazine. Prednisone can help control symptoms.

• Prevention:

  • Collect and dispose of feces from yards, playgrounds, and public places

  • Educate pet owners on the potential health hazard of roundworms especially good hygiene(wash hands) when dealing with puppies and nursing mothers

  • Routine fecal tests and deworming on pets

Baylisascaris procyonis

• Human disease: Neural Larva Migrans(NLM)

• Route of infection: Ingestion of eggs containing infective second-stage larvae from raccoon feces, contaminated soil, water, fomites, or hands. A variation of VLM and OLM, but can also migrate to the brain and spinal cord . Eggs are extremely resistant and remain viable for months to years

• Symptoms: Asymptomatic if only a few larvae ingested, visceral damage is minor, most larvae become encapsulated (walled off) in muscle or connective tissue

  • Large numbers can cause fever, leukocytosis, persistent eosinophilia, hepatomegaly and pneumonitis. Fatalities result when myocardium or CNS involved

  • Neurologic signs are sudden lethargy, loss of muscle coordination, decreased head control, torticollis, ataxia, and nystagmus; these can progress to stupor, extensor rigidity, coma and death.

• Diagnosis: Based on history, clinical signs, exposure histopathology and serological testing

• Treatment: No proven treatment is available, anthelmintics are ineffective, patients with ocular form can be treated with a laser if larvae can be visualized in the eye.

• Prevention:

  • Discourage making raccoons pets

  • Wildlife rehabbers should use caution and quarantine raccoons from other animals and use a strict anthelmintic program

  • Destroy feces and decontaminate cages and protective clothing with hot, near boiling, soapy water and bleach

Ancylostoma spp.

• Human disease: Cutaneous Larva Migrans(CLM), Creeping Eruption, Plumbers Itch, ( A. braziliense)

• Route of infection: Penetration and migration of larvae through unprotected skin, usually bare feet walking in sand , on beaches, or from soil, but can also be contracted from crawl spaces under houses, flower beds and gardens

• Symptoms: Red, tunnel-like migration tracks in the skin, severe pruritus

• Diagnosis: History of possible contamination and observation of lesions

• Treatment: Oral and topical thiabendazole

• Prevention:

  • Collect and dispose of feces from yards, playgrounds

  • Seaside Communities and beaches need leash laws and rules about pets and waste clean-up

  • Regularly deworm pets

  • Educate owners

  • Wear shoes!

Strongyloides stercoralis

• Human disease: Strongyloidiasis

• Route of infection: Penetration of larvae through unprotected skin and the migration to the intestines, sometimes migrate through lungs on way to intestines where they mature to adult stage and reproduce

• Symptoms: Respiratory symptoms, coughing, pneumonia; intestinal symptoms, diarrhea, emaciation, severe infections can cause death

• Diagnosis: Direct fecal smear, fecal flotation, or Baermann technique to identify larvae

• Treatment: Ivermectin or thiabendazole

• Prevention:

  • Collect and dispose of feces from yards, playgrounds

  • Seaside Communities and beaches need leash laws and rules about pets and waste clean-up

  • Regularly deworm pets

  • Educate owners

  • Wear shoes!

Trichinella spiralis

• Human disease: Trichinosis

• Route of infection: Ingestion of partially cooked or raw pork products containing infective larvae that migrate throughout the body via the circulatory system invading various tissues and encysting in only striated skeletal muscle

• Symptoms: Early abdominal syndrome-enteritis, malaise, nausea, vomiting, anorexia, mild fever, abdominal pain, or diarrhea

• Later general trichinosis syndrome-occurs weeks to months after the abdominal syndrome, allergic vasculitis, hemorrhage, periorbital edema, fingernail-bed and conjunctival hemorrhages, myalgia(muscle pain), muscle weakness. Severe cases develop immune-mediated myocarditis, pneumonitis and encephalitis.

• Diagnosis: During muscle phase of disease through blood hemograms and serum chemistries

• Treatment: Benzimidazole anthelmintics, particularly mebendazole, flubendazole, andcambendazole

• Prevention:

  • Cook all pork to 160 degrees Fahrenheit, microwave ovens aren’t reliable, cause ‘cold spots’

  • Freezing pork to 5 degrees Fahrenheit for 20 days, -10 degrees for 10 days or -22 degrees for 6 days

  • Gamma irradiation of pork by packing industry

• All case need to be reported to state and federal authorities

Sarcoptes scabei canis

• Human disease: Canine Scabies

• Route of infection: Direct contact from infested dogs

• Symptoms: Characteristic lesions on the trunk, arms, abdomen, and rarely the face and genitalia, lesions are described as papules or vesicles, causes extreme pruritus

• Diagnosis: Skin scrapings are rarely positive, usually diagnosed by observation of typical lesions in skin with history of possible contact with infested dog

• Treatment: Antihistamines relieve the itch and topical steroid creams reduce papules and vesicles, antibiotics prevent secondary bacterial infection

• Prevention: Avoid contact with infested dogs