PREFINAL: THE FILARIAE Flashcards
blood feeding arthropod vector-borne nematodes
THE FILARIAE
LYMPHATIC FILARIAE:
- Wuchereria bancrofti
- Brugia malayi
SUBCUTANEOUS FILARIAE:
- Loa loa
- Onchocerca volvulus
Filariae that causes infection in the
abdomen
SEROUS CAVITY
Considered one of the most delabilating diseases that is known in the man
LYMPHATIC FILARIAE
Wuchereria bancrofti common name
Bancroft’s filarial worm
Wuchereria bancrofti can cause
Bancroftian filariasis
creamy white, long and have filiform shaped
w. bancrofti adult worm
270-290 um
Small snake-like organism
Moved along red blood cells
Enclosed in a hyaline sheath, Sheathed
Sheath of microfilaria is much longer than the microfilaria itself
When stained, shows dark staining nuclei (important identifying features) and tail end culminates in a point that is free of nuclei
w. bancrofti MICROFILARIA
intermediate Hosts of w. bancrofti
Aedes
Anopheles
Culex
definitive Host of w. bancrofti
human
mot of wuchereria bancrofti
mosquito bite
periodicity of wuchereria bancrofti
nocturnal
diagnostic stage of w. bancrofti
Sheathed microfilariae
infective stage of w. bancrofti
3rd STAGE LARVAE
Brugia malayi common name
malayan filarial worm
Brugia malayi common name
malayan filarial worm
Brugia malayi can cause
MALAYAN FILARIASIS
MALE: 13-23 mm in length
FEMALE: 43-55 mm
b. malayi adult worm
- sheated
When stained, shows 2 distinct nuclei at the end of the tail
b. malayi MICROFILARIA
INTERMEDIATE HOSTS of b. malayi
Mansonia
Definitive host of b. malayi
humans
PERIODICITY of b. malayi
nocturnal and subperiodic
Can be acquired during childhood
May take years to manifest itself
Can be asymptomatic, acute stage or chronic stage
Lymphatic localization (important for parasite survival)
Lymph is less aggressive than bloodbecause there is no platelets, no complement system, no coagulation, no granulocytes and less violent
LYMPHATIC FILARIASIS
- parasite induced lymphatic dilatation, common feature of patent infection (parasitic org. can be demonstrated in the body)
- Lymph node/system dilates
LYMPHANGIECTASIA
Growth of lymphatic vessels due to the inducement of proliferation of lymphatic endothelial cells (because of the antigens introduced by filarial parasites)
LYMPHANGIOGENESIS
LYMPHANGIOGENESIS can lead to
LYMPHEDEMA
swelling of
lymph due to increased lymph fluid
LYMPHEDEMA
limbs like elephants
ELEPHANTIASIS
Most common acute manifestation of LF
Localized pain
Lymphadenitis or lymphangitis
ACUTE DERMATOLYMPHANGIOADENITIS (ADLA)
Most common chronic manifestation of LF
Most common affected: LOWER LIMBS(but upper limb and male genitalia can be affected also)
Progression to ELEPHANTIASI
LYMPHEDEMA
obstructions of the lymphatic in the
tunica vaginalis
Formation of HYDROCELE (CHYLOCELE)
accumulation of fluid or hydrocele fluid (clear or straw colored)
HYDROCELE
milky fluid (presence of lymph fluid)
- Accumulates in the sac of the testes of the male patients
CHYLOCELE
(common and more severe)
GENITALS – BANCROFTIAN
FILIARISIS
(less common and severe)
GROIN - MALAYAN FILIARIASIS
Immunologic hyper-responsiveness to mature/maturing worms
Typically occurs from foreigners infected by LF from endemic areas
EXPATRIATE SYNDROME
(enlargement of lymph nodes)
LYMPHADENITIS
(inflammation of lymphatic channels)
LYMPHANGITIS
Clinical manifestation is not present and microfilaria is not seen in the blood but microfilaria hides in tissues specifically LUNG TISSUE
Occult form of FILIARIASIS
May progress to CHRONIC PULMONARY FIBROSIS and RESPIRATORY FAILURE if untreated
High titers of IgE (Ig of parasite)
TROPICAL PULMONARY EOSINOPHILIA
Milky – chyle/lymph fluid leakage
URINE
Traditionally accepted procedure
for diagnosis
MICROSCOPIC FINDINGS of
MICROFILARIA IN THE BLOOD
o Microfilariae in wet/thick blood
smears (8pm-4am due to
NOCTURNAL)
o Knott’s Concentration Method
/Nucleopore Filter – for low
infections
o Chronic Infections may not be
demonstrable in the peripheral
blood cause by low intensity of
infection, dead worms or
obstructive lymphatics due to
increased no. of parasites
BLOOD
8pm to 4am collection
thick and blood smear for lymphatic filariae
3 mg/kg DEC SINGLE DOSE
o Allows collection during daytime
o Stimulate the microfilaria to migrate in the peripheral circulation and collect blood through blood smears
DEC/ DIETHYLCARBAMAZINE
PROVOCATIVE TEST
o PREFERRED
o Antigens from microfilaria
o Latent infections (infections that are delayed/natutulog na parasite)
o Mainly done using IMMUNOCHROMATOGRAPHIC CARD TEST
o ANTIGEN DETECTION STRIP (card) TESTS – RDTs (sensitive and specific)
CIRCULATING FILARIAL ANTIGENS
(CFA)
Growth of mosquito inside the laboratory
XENOMONITORING OF MOSQUITOES
Growth of mosquito inside the laboratory
XENOMONITORING OF MOSQUITOES
MICROSCOPIC COMPARISON using
STAINED THICK BLOOD FILMS
MICROSCOPIC COMPARISON using
STAINED THICK BLOOD FILMS
Mean length (um) of w. bancrofti
290
Mean length (um) of b. malayi
222
Cephalic space: breadth of w. bancrofti
1:1
Cephalic space: breadth of b. malayi
2:1
Sheath in Giemsa of w. bancrofti
unstained
Sheath in Giemsa of b. malayi
pink
Nuclei of w. bancrofti
Regularly spaced, separately situated
nuclei of b. malayi
Irregularly spaced, and overlapping
tail of w. bancrofti
Single row of nuclei that does not reach the tail’s end
tail of b. malayi
Single row of nuclei that reaches the
tail’s end
terminal nuclei of w. bancrofti
none
terminal nuclei of b. malayi
2 nuclei, which bulge the cuticle, conspicuously placed
Appearance in blood film of w. bancrofti
Smoothly curved
Appearance in blood film of b. malayi
kinky
Innenkorper length (um) of w. bancrofti
34
Innenkorper length (um) of b. malayi
30.7
TREATMENT of LYMPHATIC FILARIAE
DEC (DIETHYLCARBAMAZINE)
- Drug of Choice
- 6mg/kg for 12 CONSECUTIVE DAYS
- Discover in 1948
Loa loa common name
AFRICAN EYE WORM
Typically white in color and Threadlike appearance
L. loa ADULT WORM
248-300 um
Sheathed
When stained, shows tail with continuous end of nuclei (1 nuclei)
L. loa MICROFILARIA
DIAGNOSTIC STAGE OF LOA LOA
MICROFILARIAE IN BLOOD AND
TISSUES
ADULT WORMS EXTRACTED
INFECTIVE STAGE OF LOA LOA:
3RD STAGE LARVAE
INTERMEDIATE HOST of l. loa
CHRYSOPS FLY (DAY BITING FLY)
DEFINITIVE HOSTS of loa loa
humans
mot of loa loa
fly bite
PERIODICITY of l. loa
DIURNAL (they can be found during the day)
Transient subcutaneous swellings
LOIASIS
CALABAR/FUGITIVE SWELLINGS
- MICROFILARIAE IN GIEMSA STAINED IN BLOOD (10:15 AM – 2:15 PM)
Extraction of adult worms on body
locations
Serologic testing
BLOOD (DIAGNOSIS)
treatment of loa loa
DEC (DIETHYLCARBAMAZINE)
SURGICAL REMOVAL/EXTRACTION
Onchocerca volvulus common name
BLINDING FILARIA
- Thin and wirelike appearance
MALE: 25-50 mm
FEMALE: up to 500 mm
Onchocerca volvulus ADULT WORMS
150-355 um
Unsheathed (found in tissue only)
When stained, nuclei do not extend to tip of tail
MICROFILARIA
Adult filariae can live to the nodules
for approximately____
15 years
LIFE SPAN OF MICROFILARIAE of onchocerca volvulus
2 YEARS
Diagnostic stage of onchocerca volvulus
MICROFILARIAE IN BLOOD AND
TISSUES
Infective stage of onchocerca volvulus
3RD STAGE LARVAE
INTERMEDIATE HOSTS of onchocerca volvulus
SIMULIUM (BLACKFLY)
definitive Host of onchocerca volvulus
humans
mot of onchocerca volvulus
fly bite
PERIODICITY OF ONCHOCERCA VOLVULUS
NONPERIODIC (microfilaria circulate in the blood throughout 24 hour period)
SKIN: loss of elasticity and nodules
RIVER BLINDNESS: lesion formation in the eye
ONCHOCERCIASIS
Uses SLIT LAMP
OPHTHALMOLOGIC EXAM
- MICROFILARIAE IN GIEMSA STAINED TISSUE
- Tissue biopsy in the infected area –
SPECIMEN OF CHOICE - Obtained with little blood (to avoid
contamination sample)
SKIN SNIPS
treatment of onchocerca volvulus
IVERMECTIN
THERAPY CAN BE LONG BECAUSE OF THE ADULT WORM LIFESPAN (15 YEARS)