FILARIAL WORMS Flashcards
Lois is a distraught 44-year-old female visiting her primary care physician at 9:00 a.m. She describes looking in the mirror that morning and seeing a worm crawl across her eye and then disappear. On her updated patient history,
she notes she had visited the African rainforest the previous year. The physician orders a stool for ova and parasite examination, as well as a complete blood count and differential. The blood is drawn at 11:30 a.m. on the same
day as the office visit at a draw site near Lois’ home. The stool parasite examination proves to be negative. The automated blood count shows increased eosinophils and a Giemsa stained blood film is prepared. An evening shift medical laboratory scientist observes a worm-like form on the blood smear that is 275 µm in length. There is a stained sheath and nuclei extend to the tip of the tail.
Questions to Consider
1. What is the scientific name of the organism observed?
2. What is the significance of her travel history?
3. Determine if the blood sample was drawn appropriately.
4. Propose treatment options for this individual.
- Loa loa
- Loa loa, is known to inhabit areas of Africa
especially the rain forest belt and as such is
referred to as the African Eye Worm. It is
estimated that the infection rates may be over
70% in the areas in which a large vector
population exists. - Yes, the blood sample was drawn at the
appropriate time. Samples collected between
10:15 am and 2:15 pm yield the best recovery
rate of Loa loa microfilariae. This parasite
exhibits diurnal periodicity. - Surgical removal is the treatment of choice for
the removal of adult Loa loa worms. The
medication of choice for the treatment of Loa
loa is diethylcarbamazine (DEC).
Speciation of the microfilariae can be done by recognition of the distribution of nuclei in the tip of the tail and the presence or absence of a delicate transparent covering known as the:
A. Flilariform
B. Cuticle
C. Sheath
D. Nucleus
C
What type of periodicity is exhibited if microfilariae appear in the blood of an individual at 2:00 p.m. each day?
A. Nocturnal
B. Diurnal
C. Subperiodic
D. Biannual
B
Which of the following is similar for all microfilariae discussed?
A. Presence of a sheath
B. Ability to exhibit periodicity
C. Location of the adult worms
D. The basic life cycle
D
Common name of Wuchereria bancrofti
Bancroft’s malayi, Bancroft’s filarial worm
Wuchereria bancrofti
Disease/s caused: Bancroftian filariasis, Wuchereriasis
-Elephantiasis of the ______ extremities, lymphatics of the? _______
Habitat: _________ extremities
Specimen of choice?
Vector?
Body curves: Regularly smoothly curved, ______ sweeping
Body nuclei: Coarse, ___________
Tail end: is there a nuclei?
Periodicity?
This serves as an important identifying feature.
It serve as the laboratory diagnostic method of choice
Disease caused:
-Lower; scrotum
Habitat:
-Lower extremities
Specimen of choice: Blood
Vector: Culex pipiens
-Aedes, Culex, and Anopheles have been shown to be biologic vectors of Wuchereria
Body curves: graceful sweeping
Body nuclei: coarse, well separated
Tail end: No nuclei on the tip (Wala na)
Periodicity: Nocturnal
Important identifying feature: When stained, the central axis shows dark-staining nuclei
Fresh Giemsa-stained blood
Diagnosis of infection with Wuchereria bancrofti is best accomplished by:
A. Examination of stained peripheral blood taken during the night
B. Examination of stained tissue biopsy taken during the night
C. Use of serologic testing with blood taken during the day
D. Examination of stained lymph fluid taken during the day
A
Which of the following, in combination with albendazole, has proven to be an important drug for the treatment of Bancroft’s filariasis?
A. Doxycycline
B. Ivermectin
C. Metronidazole
D. None of the above
B
Common name of Brugia malayi
Malayan filarial worm
Brugia Malayi
Disease/s caused: Malayn filariasis
-Elephantiasis of the ______ extremities
Habitat: _________ extremities
Specimen of choice?
Vector?
Body curves: Irregular or Regular? Twisted; stiff with?
Body nuclei: Coarse, tend to ___________
Tail end: is there a nuclei?
Periodicity?
It serve as the laboratory diagnostic method of choice
Disease caused:
-upper
Habitat:
-Upper lymphatics
Specimen of choice: Blood
Vector: Mansonia spp., Anopheles spp.
Body curves: Irregular and twisted, stiff with secondary kinks
Body nuclei: coarse, tend to overlap
Tail end: 2 widely spaced nuclei; blunt tip
-B2
Periodicity: Nocturnal
Fresh Giemsa Stained Blood
Which of the following can be used in the differentiation and identification of Brugia malayi?
A. Absence of a sheath
B. Absence of nuclei in the tail
C. Presence of a sheath that is very difficult to observe on Giemsa stain
D. Presence of two terminal nuclei in the tail
D
Select the ideal time period to collect blood samples for examination for the presence of the microfilariae of Brugia malayi.
A. 10:00 p.m. to 4:00 a.m.
B. 10:00 a.m. to 4:00 p.m.
C. 4:00 p.m. to 8:00 p.m.
D. Any time of the day or night
A
Common name of Loa Loa
Eye worm, Loa worm
Loa Loa
Disease/s caused: Loasis
-_______ and ______ swelling
Habitat: __________ and ________ tissues
Specimen of choice?
Vector?
Body curves: Irregular or Regular? is it twisted?
Body nuclei: Coarse, tend to ___________
Tail end: is there a nuclei?
Periodicity?
It serve as the laboratory diagnostic method of choice
Disease caused:
-Fugitive and Calabar swelling
Habitat:
-Subcutaneous and muscle tissues
Specimen of choice: Blood
Vector: Chysops fly (Deer fly/ mango fly)
Body curves: Irregular, twisted
Body nuclei: coarse, tend to overlap
Tail end: Nuclei is present; rounded tip
-Lumuluwa
Periodicity: Diurnal (10 am- 2pm)
Fresh Giemsa Stained Blood
A small threadlike worm is observed under the conjunctiva of the eye. What organism and form is most likely?
A. Wuchereria bancrofti adult
B. Brugia malayi microfilaria
C. Onchocera volvulus larva
D. Loa loa adult
D
