Tissue Nematoda Summary for medical parasitology, Geographical distribution Hosts Mode of transmission Diagnosis Treatment

1. Summary Tissue
Nematodes

2. Nematode Geographical Distribution
Wuchereria bancrofti Sub-Saharan Africa , Madagascar
Brugia malayi Southeast Asia.
Loa loa Africa
Onchocerca volvulus Africa, with additional foci in Latin America
and the Middle East.
Geographical Distribution:

3. Species D.H. I.H. I.S D.S. (Microflaria for all)
W. bancrofti Human N/A Flariform Larvae Sheath: (loose) Curves: (smooth) nuclei at tail: (free)
B. malayi Human,
monkeys
N/A Flariform Larvae Sheath: (loose) Curves: (Kinky) nuclei at tail: (2)
Loa loa Human N/A Flariform Larvae Sheath: (Tight) Curves: (Kinky) nuclei at tail: (full)
O. volvulus Human N/A Flariform Larvae Sheath: (unsheathed) Curves: (smooth) nuclei at tail:
(free)
Hosts:
Diagnostic stages best examination times:
W. Bancrofti  Nocturnal in blood
B. Malayi  Nocturnal in blood
Loa loa  Diurnal in blood
O. Volvulus  Non-periodic in S.C tissue

4. Nematode Mode of Transmission
W. bancrofti
When mosquito vector bite for blood meal, it introduces filariform (L3) larvae
on human skin & enter to S.C tissue by :
Penetrating the skin, OR
Enter through bite wound or abrasion (usually in pairs)
B. malayi
Loa loa
O. volvulus
Mode of Transmission:

5. Nematode Main Diagnosis Additional
Wuchereria
bancrofti
• MF in peripheral blood smears
(nocturnal collection)
• Knott technique increase sensitivity
immunochromatographic test for
antigen detection
ELISA for antibody detection
Brugia malayi
Loa loa • MF in peripheral blood smears or
adults in the subconjunctiva. (Diurnal
collection)
• Knott technique increase sensitivity
The presence of Calabar swellings
can aid in the diagnosis.
Onchocerca
volvulus
• MF in skin snips or adults in biopsy
specimens of skin nodules. (No
preferred time for collection)
• Mazottii test
• Patch Test
• Serology (has cross reactivity)
• Radiology (US)
Diagnosis:

6. Treatment:
Nematode Treatment
W. bancrofti • Monoinfection: (no evidence of SC filariasis)
• DEC:
• 6 mg/kg PO single dose
• In case of tropical pulmonary eosinophilia:
• 6mg/kg for 21 days
• Doxycycline:
• 200 mg/d po for 6 weeks
• Coinfection: (with onchocerciasis)
• First treat onchocerciasis with ivermectin: 150 ug/kg PO single dose 
Then after one month start DEC
• Coinfection: (with Loa loa)
• If loa loa <2500 MF:
• DEC
• 8-10 mg/kg/d PO for 21 days
• If loa loa >2500 MF:
• Combination of ivermectin + DEC
• Refer to expert center
• Surgical intervention:
• For obstructive filariasis
B. malayi

7. Nematode Treatment
Loa loa • Monoinfection:
• If loa loa <2500 MF:
• DEC
• 9 mg/kg/d PO for 21 days
• Repeat treatment after 3 weeks
• If loa loa >2500 MF:
• Start with albendazole 200 mg for 3 weeks
• Then start DEC 9 mg/kg/d PO for 21 days
• Refer to expert center
• DEC 300 mg once weekly for long term prophylaxis in residents of endemic areas
• Coinfection with onchocerciasis:
• First treat onchocerciasis with ivermectin:
• 150 ug/kg PO single dose
• Then after 6-12 months start DEC.
O.
volvulus
• Doxycycline 200 mg/day po for 6 weeks  followed by single dose of
ivermectin 150 ug/kg
• Repeat ivermectin every 3-6 months for at least 3-4 years until
asymptomatic
• DEC is Contraindicated
• Causes severe inflammatory reactions of the skin and eyes
Treatment: