Roundworm Nematode

1. Brugia malayi

2. Scientific classification
Kingdom: Animalia
Phylum: Nematoda
Class: Secernentea
Order: Spirurida
Family: Filariidae
Genus: Brugia
Species: B. malayi

3. Brugia malayi
• is a roundworm nematode, one of the three
causative agents of lymphatic filariasis in
humans.
• Lymphatic filariasis, also known as elephantiasis,
is a condition characterized by swelling of the
lower limbs.
• The two other filarial causes of lymphatic
filariasis areWuchereria bancrofti and Brugia
timori, which differ from Brugia
malayi morphologically, symptomatically, and in
geographical extent

4. Geographical distribution
• B. malayi infects 13 million people in south and
southeast Asia and is responsible for nearly 10%
of the world’s total cases of lymphatic filariasis
• B. malayi infection is endemic or potentially
endemic in 16 countries, where it is most
common in southern China and India, but also
occurs in Indonesia, Thailand, Vietnam,
Malaysia, the Philippines, and South Korea

6. Morphology
• Female adult worms measures between
43-55 mm in length by 130-170 um in
width.
• Male adult worms measures between 13-
23 mm in length by 70-80 um in width.

7. Microfilariae
• B. malayi microfilariae measures 177-230 um
in length and 5-7 um in width and have a
round anterior end and a pointed posterior
end.
• The sheath is actually the egg shell, a thin layer
that surrounds the egg shell as the
microfilariae circulates in the bloodstream.
• The microfilariae retain the sheath until it is
digested in the mosquito midgut

8. Adult
Sections of adult Brugia sp. From a lymph node, stained with hematoxylin and eosin.
Microfilariae
Posterior end of B. malayi microfilariae –
note the two distinctive terminal nuclei

10. Life Cycle
• The typical vector for Brugia malayi filariasis
are mosquito species from genera Mansonia
and Aedes.

11. Life cycle

12. Symptoms
• Asymptomatic Phase: Upon initial
infection no symptoms may be present
as microfilariae mature.
• B. Malayi is one of the causative agents
of lymphatic filariasis, a condition
marked by infection and swelling of the
lymphatic system.
• The disease is primarily caused by the
presence of worms in the lymphatic
vessels and the resulting host response.

13. • Signs of infection are typically
consistent with those seen in
bancroftian filariasis – fever,
lymphadenitis, lymphangitis,
lymphedema, and secondary bacterial
infection
* Lymphadenitis cause swelling of the
lymph nodes that may occur prior to
maturation.

14. * Lymphangitis
• Inflammation of the lymphatic vessels
usually after maturation.
• The affected lymphatic vessel becomes
distended and tender, and the overlying
skin becomes erythemous and hot.
Abscess formation and ulceration of the
affected lymph nodes occasionally occurs
during B. malayi infection

15. Lymphadenitis
Lymphagitis

16. *Lymphedema (elephantiasis)
• It is the enlargement of the limbs.
• Consistent irritation of lymphatic vessels
leading to blockages caused by dead adult
worms, inflammatory fibrosis, or
granulomatous reactions.
• Elephantiasis resulting from B.
malayi infection typically affects the lower
extremities of the legs and arms.

18. * Secondary bacteria infections
• lymph node failure caused by extended
overstimulation

19. Diagnosis
• The standard method for diagnosing active
infection is the identification of microfilariae
in a blood smear by microscopic examination.
• The microfilariae that cause lymphatic
filariasis circulate in the blood at night (called
nocturnal periodicity).
• Blood collection should be done at night to
coincide with the appearance of the
microfilariae, and a thick smear should be
made and stained with Giemsa or hematoxylin
and eosin.

20. • Serologic techniques provide an
alternative to microscopic detection of
microfilariae for the diagnosis of
lymphatic filariasis.
• Patients with active filarial infection
typically have elevated levels of
antifilarial IgG4 in the blood and these
can be detected using routine assays.

21. Treatment
• Diethylcarbamazine (DEC)- is the drug of
choice
• Doxycycline (200mg/day for 4-6 weeks).
• In patients with Elephantiasis, surgical
procedures are required as chemotheraphy
cannot reverse the fibrotic changes.
• Levamisole hydrochloride- also been used for
the treatment of W. bancrofti, B. malayi and
tropical pulmonary eosinophilia.
• Ivermectin- shown great promise in the
treatment of filariasis and eosinophic-lung.

22. Prevention and Control
The best way to prevent lymphatic filariasis is to
avoid mosquito bites.
The mosquitoes that carry the microscopic worms
usually bite between the hours of dusk and dawn.
If you live in an area with lymphatic filariasis:
• at night
– sleep in an air-conditioned room or
– sleep under a mosquito net
• between dusk and dawn
– wear long sleeves and trousers and
– use mosquito repellent on exposed skin.

23. The end 