Final Lab Practical Flashcards
What parasites are in Phylum Nemata?
Roundworms
What are nematodes?
Roundworms
What is the kingdom and phylum of nemata?
Kingdom –> Animalia (metazoa)
Phylum –> Nemathelminthes
Nematode shape
Elongated, cylindrical,
unsegmented
Nematode head end
Hooks and sucker absent. Well- developed buccal capsule with teeth or cutting plates seen in some species
Nematode alimentary canal
Complete with anus
Nematode body cavity
Present. Viscera
remains suspended in
the pseudocele
Nematode sex classifications
Separate (diecious)
Nematode life cycle
Monoxenous (except
filarial worms and
Dracunculus spp.
What is this picture depicting?
Nematode digestive, excretory, and nervous system
Female vs male reproductive system in nematodes
Didelphic female vs monodelphic female nematode
Nematode life cycle
Egg –> L1 + M1 –> L2 + M2 –> L3 + M3 –> L4 + M4 –> Adult
Nematode life cycle from larvae
Larvae –> free in blood and lymph –> develop in bloodsucking diptera
What does Onchocerca volvulus cause?
Onchocerciasis or “river blindness”
What is Onchocerca volvulus transmitted through?
Transmitted to humans through exposure to repeated bites of
infected blackflies of the genus Simulium.
What are symptoms of river blindness?
Symptoms include severe itching, disfiguring skin conditions,
and visual impairment, including permanent blindness.
What is the female worm of Onchocerca volvulus?
Female worm is viviparous
Onchocerca volvulus Epidemiology
- Venezuela
- Brazil
- Nigeria
- Sudan
- Ethiopia
- Uganda
DH, IH, and infective stage of Onchocerca volvulus
DH: humans
IH: females of black flies (Simulium spp.)
Infective stage: third-stage filariform larva
Location of adult Onchocerca volvulus
in nodules in subcutaneous connective tissue
of infected persons (lifespan: 15 years).
Mode of transmission of Onchocerca volvulus
black flies deposit larvae in the skin while
biting
Adult morphology of Onchocerca volvulus
Adult:
–> Whitish, with transverse striations on the
cuticle
–> Posterior end is curved (“curved tail”)
–>Male is smaller
What nematode is this?
Onchocerca volvulus
Onchocerca volvulus microfilariae morphology
Microfilaria:
- -> Unsheathed
- -> `Non-periodic
Skin manifestation of Onchocerca volvulus
Clinical features
–> Due to inflammatory response around the worm (adult and
microfilariae)
–> Pruritus, dermatitis, onchocercoma (subcutaneous nodules), and
lymphadenopathies
Ocular manifestation of Onchocerca volvulus
Clinical features
- -> Photophobia, gradual blurring of vision
- -> Total blindness.
Onchocerca volvulus Diagnosis
Microscopy:
- -> Presence of microfilariae in skin snips
- -> Presence of adults in biopsy specimens of skin nodules.
Serology
Molecular diagnosis
(PCR from skin snips)
Onchocerca volvulus Treatment
–> Ivermectin: at least once yearly for 10 to 15 years (150 ug/kg).
–> Surgical excision of nodules when occur in head
–> Anti-endosymbiont of filarial parasites
Onchocerca volvulus Prevention
–> Treatment of infected patients (mass drug administration of the
medicine Mectizan ®)
–> In 1974, WHO launched a control program using larvicide for
vector control (spraying of insecticides by helicopters and
airplanes)
Onchocerca cervicalis
Found in nuchal ligament (adults), skin, and ocular tissues in horses
IH: Culicoides spp.
Onchocerca lupi
Found in ocular tissue in dogs, with associated lesions and
inflammatory response
Also reported in cats, zoonotic
IH: unknown
What does Wuchereria bancrofti cause?
Lymphatic Filariasis
How is Wuchereria bancrofti spread?
Is spread from person to person by mosquitoes
Where does Wuchereria bancrofti live?
The adult worms live in the human lymph system for many
years, leading to lymphatic dysfunction
Wuchereria bancrofti lymphatic impairment
leads to painful, disabling, and social-
stigmatized deformities of limbs, scrotum or breast.
DH, IH, and infective stage of Wuchereria bancrofti
DH: human
IH: Culex spp. mosquitoes
Infective stage: third-stage filariform larva
Mode of transmission of Wuchereria bancrofti
by bite of mosquito carrying filariform larva
Location of Wuchereria bancrofti adults and microfilariae
Location of adult
–> lymphatic system.
Microfilariae –> found in blood.
Life cycle of Wuchereria bancrofti
Wuchereria bancrofti Morphology
Whitish, thread-like shape
• Males: up to 40 mm long
• Females: 80-100 mm
long
Wuchereria bancrofti Microfilaria Morphology
- Sheathed
- Periodic in peripheral blood
- Biting habits of vector
- Sleeping habits of host
Which is O. volvulus and which is W. bancrofti?
Left –> W. bancrofti
Right –> O. volvulus
Wuchereria bancrofti Clinical features
• Mechanical factors + inflammatory response
• Chronic response: granuloma formation, calcification, blockage
of lymphatic drainage
- Lymphadenitis, lymphedema, lymphangiovarix
- Hydrocele
- Lymphorrhagia: chylous urine, chylous diarrhea, chylotorax
- Elephantiasis
Wuchereria bancrofti Diagnosis
Demonstration of microfilaria in blood, chylous urine, exudate of
lymph and hydrocele fluid
Wuchereria bancrofti Treatment
• Diethylcarbamazine (DEC) PO 6 mg/kg x 12d (allergic
reactions)
- Mass therapy
- Ivermectin (no effect over adults)
- Doxycycline (targeting Wolbachia)
Wuchereria bancrofti Prevention
- Eradication of the vector mosquito
2. Detection and treatment of carriers
Another name for Necator americanus
American Hookworm
Another name for Ancylostoma duodenale
Intestinal Hookworm
What disease does Ascaris lumbricoides cause?
Ascariasis
What does Enterobius vermicularis cause?
Enterobiasis or Pinworm Infection
What does Trichuris trichiura cause and what is another name for it?
Trichuriasis or Human Whipworm
What does Trichinella spiralis cause?
Trichinellosis or Trichinosis)
What are the bursate nematodes?
- Ancylostoma
- Necator
Superfamily –> Ancylostomatidae
What are the non-bursate nematodes?
Ascaridoidea –> Ascaris
Oxyuridae –> Enterobius
Trichuroidea –> Trichuris
Trichinelloidea –> Trichinella
Features of hookworms
Buccal capsule well developed; leaf crowns and teeth usually present. Direct life cycle; infection by J3 in environment
Features of Ascaridoidea
Large white worms. Direct life cycle; infection by J3 in egg
Features of Pinworms
Female has long pointed tail. Direct life cycle; infection by J3 in egg
Features of Whipworms
Whip-like or hair-like worms. Direct or indirect life cycle; infection by J1
Necator americanus &
Ancylostoma duodenale
(Intestinal “hookworms”)
What is the old world hookworm and what is the new world hookworm?
Old world –> A. duodenale
New world –> N. americanus
Location of adult hookworms
small intestine (jejunum and duodenum).
•Life cycle is direct. Female is longer than male.
DH and infective stage of hookworms
- DH: Humans, and other mammals.
* Infective form: third-stage filariform juvenile (L3) in environment.
Mode of transmission of hookworms
penetration of infective filariform larva into the skin.
Clinical features of hookworms
skin itching and rash; spoliative action (protein and iron deficiency), anemia; intestinal inflammation, diarrhea.
Dx of hookworms
eggs in stool; concentration techniques
Tx of hookworms
available (mebendazole, albendazole); iron supplementation
Prevention of hookworms
avoid barefoot walking where hookworms could happen; not defecating outdoors
Intestinal hookworm Life cycle
Filariform larvae (infective stage) of hookworm
Hookworm egg (fully developed)
Intestinal hookworm
Intestinal hookworm Morphology
N. Americanus vs A. duodenale morphological differences
A. ctenomyos
Ascaris lumbricoides
What is the largest nematode infecting humans?
Ascaris lumbricoides
Location of Ascaris lumbricoides
small intestine
DH and infective form of Ascaris lumbricoides
- DH: human (and some non-human primates)
* Infective form: embryonated egg containing rhabditiform
Clinical features of Ascaris lumbricoides
spoliative action (protein and vitamin A deficiency); intestinal obstruction, intussusception, perforation. Also, could be in lungs (pneumonia)
Dx and Tx of Ascaris lumbricoides
- Dx: eggs in stool, juveniles in sputum, adults in stool
* Tx: available (albendazole)
Prevention of Ascaris lumbricoides
avoid potentially contaminated soil; good personal hygiene actions; not defecating outdoor
Ascaris lumbricoides Life cycle
What species of nematode do these eggs belong to?
Ascaris lumbricoides
Enterobius vermicularis
Where are pinworms found in the world?
Worldwide. Most common helminthic infection in United States and Europe. Seen mostly in children and among family members. Direct life cycle.
Location of Enterobius vermicularis adult
large intestine, cecum, perineal region
DH and infective stage of Enterobius vermicularis
- DH: Humans, chimpanzee
* Infective stage: embryonated egg containing infective larva
Mode of transmission of Enterobius vermicularis
by ingesting eggs by means of contaminated fingers or autoinfection (transferring eggs to the mouth with hands that have scratched the perianal area)
Clinical features of Enterobius vermicularis
pruritus ani, discomfort, enuresis. Sometimes, female genital-urinary symptoms. Abdominal pain. Secondary lesions and bacterial infection due to perineal scratching
Dx, Tx, and prevention of Enterobius vermicularis
- Dx: eggs in perineal and anus skin (transparent tape technique, right after waking-up), and under the nails; adults 2-3 hours after asleep. Difficult in stool.
- Tx: available (mebendazole, albendazole, or pyrantel pamoate)
- Prevention: proper hand washing.
Enterobius vermicularis Life cycle
Enterobius vermicularis
Enterobius vermicularis
Trichuris trichiura
Trichuriasis or “Human Whipworm”
What is the distribution of Trichuris trichiura?
Worldwide. Third most common roundworm in humans.
Location of Trichuris trichiura adult
cecum and ascending colon
DH of Trichuris trichiura
human, primates. Direct life cycle.
Clinical features of Trichuris trichiura
in heavy infections, painful diarrhea that contain a mixture of mucus, water, blood and typically smells worse than usual.
Infective stage of Trichuris trichiura
embryonated egg containing infective larva
Mode of transmission of Trichuris trichiura
by ingesting eggs in hands or food in contact with contaminated soil
Dx, Tx, and prevention of Trichuris trichiura
- Dx: eggs in stool (concentration technique)
- Tx: available (albendazole, mebendazole)
- Prevention: proper hand washing; avoid soil and food potentially contaminated with human feces. Not defecating outdoor.
Trichuris trichiura Life cycle
Trichuris trichiura
Trichuris trichiura
Trichinella spiralis location of adult
small intestine
DH and infective form of Trichinella spiralis
- DH: different wild and domestic mammal species. Human acts as accidental host (dead-end for parasite).
- Infective form: Encysted larvae in the striated muscles of pigs and other animals.
Mode of transmission of Trichinella spiralis
ingestion of larvae encysted in meat
Clinical features of Trichinella spiralis
gastrointestinal symptoms in the first days. Muscle pain, fever, itchy skin
or rash, weakness, cough, chills
Dx, Tx, and prevention of Trichinella spiralis
- Dx: antibody test, muscle biopsy
- Tx: when early diagnosis is performed, anti-helminthic drugs are affective. After muscle invasion, symptomatic treatment is prescribed.
- Prevention: cook meat to safe temperatures. Hand washing.
Trichinella spiralis Life cycle
Trichinella spiralis Morphology
Trichinella spiralis Morphology
Arthropods (Phylum Arthropoda)
Invertebrates with hard chitinous exoskeleton, a segmented body and jointed limbs.
Insecta vs Arachnida
Arthropods Classification
Arthropods Medical importance
- Injury: bite, sting, cause allergic reactions, itchy, inflammation, blood loss
- Disease transmission (acting as vector or definitive host)
- Secondary bacterial infection
- Social stigma
Insecta: Phthiraptera (Lice)
Lice
Pediculus humanus head lice vs body lice
head louse (P. h. capitis) body louse (P. h. humanus ).
Pediculus humanus DH
human
Pediculus humanus epidemiology
worldwide. Children 3 to 11 years of age are infested most often. Body lice are also cosmopolitan but are less common
Pediculus humanus food
blood (sucking louse)
Pediculus humanus clinical features
tickling feeling of something moving in the hair, itching, caused by an allergic reaction to louse saliva, and irritability. Secondary bacterial infection may be a complication.
Lice mode of transmission
head-to-head contact, typically at school.
Lice tx and dx
- Dx: finding a live nymph or adult louse on the scalp or in the hair of a person
- Tx: pediculicides (natural pyrethrin, synthetic pyrethroids and other insecticides)
Lice- Pediculus humanus Life cycle
Egg → nymph → adult
Pediculus humanus
Insecta: Diptera
Flies and mosquitos
What are the main two species of mosquitos?
Culex spp. and Anopheles spp.
What are culex spp vectors for?
Vector for West Nile virus and filarial nematodes
How are Culex spp eggs laid?
Eggs are laid in clusters
(cigar-shaped)
Eggs lack lateral air floats
What do culex spp look like?
Adults: transparent wings,
capable to fly long distances
How do culex spp rest?
Resting: parallel to the
surface
What are anopheles vectors for?
Vector for Plasmodium spp.
and filarial nematodes
How are Anopheles spp. eggs laid?
Eggs are laid singly (boat-
shaped)
Eggs present lateral air floats
What do Anopheles spp. adults look like?
spotted wings, incapable
of flying long distances
How do Anopheles spp. rest?
angle its body 45
degrees
Mosquitoes- Culex spp. Life Cycle
Mosquitoes- Anopheles spp. Life Cycle
Mosquitoes Morphology
Insecta: Siphonaptera
Fleas
Pulex irritans distribution
Worldwide except for the Arctic
Pulex irritans hosts
mammals, principally humans.
Pulex irritans location of adult
host’s surface when it needs to feed. When not feeding can be found in environment
Pulex irritans food
blood; larvae feed on various organic matter (feces of adults).
Pulex irritans clinical features
itchy, redness, loca inflammation, secondary infections caused by scratching are common
Pulex irritans Dx and Tx
- Dx: adults in the host -> mount in slides to differentiate species.
- Tx: no scratch, wash the bites, lotions to treat the itching, most important -> house hygiene practices
Flea- Pulex irritans Life cycle
Holometabolous insects: have a four-part life cycle consisting of eggs, larvae, pupae, and adults.
*P. irritans lay eggs on
the host, but
they fall off.
Pulex irritans
Acari: Metastigmata
(Ticks)
Ticks distribution
Worldwide (ticks are found wherever their host species occur)
Hard tick vs Soft tick
Ixodidae (hard ticks);
Argasidae (soft ticks).
Tick hosts
vertebrates – varies according to species.
Tick clinical features
Clinical features: itching, and irritability. Secondary bacterial infection (for scratching) may be a complication. Blood loss. Tick-borne diseases. Tick paralysis.
•Tick-borne diseases: bacteria, viruses and protozoa. In the United States, Lyme disease is the most reported vector-borne disease
Tick Dx and Tx
Dx: finding a live adult in the host.
- Tx: remove the tick (be sure to remove the buccal parts with forceps).
- Their bodies slowly enlarge to accommodate the amount of blood ingested.
Tick morphology
Mites
Mites –> Sarcoptes
Nematomorpha
Horsehair worms
Where can Nematomorpha be found
Larvae parasitic of arthropods (primary beetles and crickets).
• Free-living adult → can be found in damp areas (watering troughs, swimming pools, streams, puddles, and cisterns)
Differences of Nematomorpha with nematodes:
Hairworms lack cephalic papillae, lateral
epidermal cords, secretory-excretory systems,
and spicules.
•Female hairworms’ genital opening is located in
the posterior end (not near to the middle as in
Nemata).
•Hairworm adults have a poorly/absent digestive
system
•Hairworms have a true larval stage that
undergoes significant morphological change.
Nematomorpha Life Cycle
•Larva is happening in
arthropod host. They
rapidly develop on adults
upon contact water.
•Dioecious species mate
and lay eggs strings.
•Larvae develop, infect, and
encyst indiscriminately
within a variety of aquatic
animals.
Nematomorpha Morphology
Class Pentastomida
“Tongue worms”, “Pentastomas”
Where is Pentastomida found
Found in the respiratory passages and viscera of vertebrates (overall, reptiles and carnivores mammals)
Linguatula genus
adult parasites occurring in the nasal passages and sinuses of dogs, cats, foxes and primates.
Human infection: contact with dog saliva or eating raw ruminant viscera.
Armillifer genus
is found in the lungs of large snakes but has also been reported in the viscera of primates and humans.
Human infection: eating raw snake meat, or with water contaminated with snake secretions.
Class Pentastomida Morphology
- Annulated body
- Anterior end with two pairs of retractable fangs or hooks
- Eggs with four- or six-legged larva are discharged by nasal secretions.
Pentastomida life cycle
If swallowed, in the appropriate host, some species could encyst in nymph form (similar to adult, without developed reproductive organs)
Pentastomida
Important steps of Necropsy
- Assign a unique identifier to the mammal immediately upon capture.
- Field preservation of mammal specimens (if possible, process ASAP after euthanasia).
- Record standard mammal measurements.
- Swept for ectoparasites.
- Necropsy.
Standard mammal measurements
Total length (mm) •Tail length (mm) •Hindfoot length (mm) •Ear length (mm) •Weight (g) e.g. 125-28-16-3 68g
What is done with the Gastrointestinal tract?
is transferred
to a Petri dish and labeled
What is done with the body cavity and organs?
are
visually inspected for parasites
What is done with host tissues?
are collected and
preserved
