2. Filariasis
• Filariasis is the common term for a group of diseases caused by
parasitic nematodes belonging to super family Filarioidea.
• Filariasis is caused by thread-like nematode worms, classified
according to their presence in the vertebrate host.
• The cutaneous group includes
– Onchocerca volvulus – River blindness
– Loa loa and
– Mansonella streptocerca;
• The lymphatic group includes
– Wuchereria bancrofti,
– Brugia malayi and
– Brugia timori and
• The body cavity group includes
– Mansonella perstans and
– Mansonella ozzardi.
3. Filariasis
• Adult worms of these parasites live in the
– lymphatic system,
– cutaneous tissues or
– body cavity of the humans
– and are transmitted through vectors (mosquito).
• Filariasis caused by nematodes that live in the
human lymph system is called Lymphatic
Filariasis .
4. • Mass drug administration in filariasis reduces the
transmission of filarial infection and disease morbidity
by decreasing the burden of microfilaremia, resulting
in suboptimal levels for transmission by disease vectors.
5. Filariasis Treatment
• Drug treatments for lymphatic filariasis attempt to reduce the
incidence of circulating microfilariae in the human population to
disrupt disease transmission.
• Drugs include annual doses of
– Albendazole plus diethylcarbamazine (DEC),
– Albendazole plus ivermectin, or
– DEC fortified salt.
• While effective on larval stages, these treatments are fairly
ineffective at killing adult worms and provide only partial benefit to
infected patients.
• Efforts to alleviate suffering and disability for infected patients focus
on hygiene aimed at decreasing secondary bacterial and fungal
infection.
6. Filariasis Treatment
Global Efforts
• In 2000, control efforts were formalized as the Global Alliance to
Eliminate Lymphatic Filariasis, a coalition with the ambitious
goal of eliminating the disease by 2020 through the distribution
of drugs.
• Control efforts are scaling up with 54 million people in 32
countries treated in 2002, an increase from just 3 million in 2000.
• Despite these admirable global efforts, eradication of filarial
diseases will be extremely challenging with current technology.
• No vaccines are available, vector control programs have ended
or are facing insect resistance, and drugs are largely ineffective
against the worm’s adult stage.
7. lymphatic filariasis in Nepal
Geographical distribution of filariasis.
Black dots indicate the site of testing and size of the dot is proportional to the
percentage of prevalence. The GIS map is colour-graded with respect to altitude.
9. Filariasis
Infection with:
• Wuchereria bancrofti (Culex mosquito)
• Brugia malayi (Mansonia mosquito)
• Brugia timori (Anopheles/Mansonia mosquito)
* Transmitted by the bite of infected mosquito responsible
for considerable sufferings/deformity and disability
* All the parasites have similar life cycle in man
* Adults seen in Lymphatic vessels
* Microfilariae seen in peripheral blood during night
10. Disease
Manifestation
• None
• Acute-Filarial fever
• Chronic-Lymphangitis, Lymphadenitis, Elephantiasis of
genitals/legs/arms
• Tropical Pulmonary Eosinophilia (TPE)
• Filarial arthritis
• Epididymoorchitis (proceeds to form hydrocele)
• Chyluria (fig-a)
Lymphangitis- Inflammation of the lymphatic channels (infection)
Lymphadenitis-Inflammation of lymph nodes
Lymphangitis Lymphadenitis
11. Management of
Lymphatic Filariasis
1. Treating the infection
2. Treatment and prevention of Acute Adenolymphangitis (ADL)
attacks
3. Treatment and prevention of Lymphoedema
Adenolymphangitis--Fever and painful
lymphadenopathy in the groin and axillae.
13. Diethyl Carbamazine
• It is the first drug for filariasis (1948)
• VD: 3-5L/kg, distributed all over the body
• Plasma t½ of usual clinical doses is 4–12 hours,
depending on urinary pH
• Excretion is faster in acidic pH.
• Elephantiasis due to chronic lymphatic obstruction is
not affected by DEC, because fibrosis of lymphatics is
irreversible.
14. Diethyl Carbamazine- MoA
• Microfilariacidal-- Very effective against Mf
• It has a highly selective effect on microfilariae (Mf).
• Lowers Mf level even in single dose
• DEC causes alteration of Mf membranes so that they are
readily phagocytosed by host immune system(tissue fixed
monocytes).
• A dose of 2 mg/kg TDS clears Mf of W. bancrofti and B.
malayi from peripheral blood in 7 days.
• However, Mf present in nodules and transudates
(hydrocoele) are not killed.
15. Diethyl Carbamazine- MoA
Slow acting macrofilaricidal
• It is also suggested that muscular activity of Mf and
adult worms is affected so that they are dislodged.
• Prolonged treatment may kill adult B. malayi and
probably W. bancrofti worms also.
• Effective against adult worms in 50% of patients in
sensitive cases.
• Thus, DEC is slow acting macrofilaricidal.
16. Diethyl Carbamazine- Effects
• DEC is active against Mf of
– Loa loa and
– Onchocerca volvulus
• The adult worm of L. loa but not O. volvulus is
killed.
• DEC reduces worm burden in ascariasis, but
efficacy is low.
17. Diethyl Carbamazine
C/U:
• Filariasis-radical cure with prolonged treatment.
• Mass preventive measures attained through
combination of DEC and albendazole, decreases
transmission of filariasis by reducing
microfilaraemia.
• Tropical eosinophila/ eosinophilic lung
(Microfilariacidal axn)
• Loaloasis – small dose given initially (25-50 mg) to
avoid severe reaction to dying Mf.
18. Diethyl Carbamazine
Adverse reactions
• Mostly due to the rapid destruction of Mf which is
characterised by
– fever,
– nausea,
– myalgia,
– sore throat,
– cough,
– headache.
• Allergic rxns- tachycardia, lymphadenopathy, rashes
• Tremors and convulsions following large doses
19. Ivermectin
• It is an extremely potent semisynthetic derivative of the
antinematodal principle obtained from Streptomyces
avermitilis.
• It is microfilaricidal but not macrofilaricidal.
• Ivermectin is DOC for single dose treatment of
onchocerciasis and strongyloidosis
Mode of action:
• GABA agonist, cause tonic paralysis of Mf, which are
then removed by RES (Reticulo endothelial system).
• Very effective against Mf (Microfilariacidal)
• No lethal effect on adult worms
20. Ivermectin
• Dose: 150 mcg/kg
• Needs to be given at a dose of 150 mcg/kg every 6-12
months for 10 years, or till patient is asymptomatic.
• Mass treatment in endemic areas Albendazole 400mg
+ Ivermectin 200mcg/kg single dose every 12 months.
• DOC in Co-endemic areas of Onchocerciasis
• Single dose effective in scabies and head lice.
• Adverse reactions are lesser but similar to that of DEC
Onchocerciasis --river blindness and Robles disease
21. Albendazole
• This anthelmenthic kills adult worms.
• No action on microfilariae
M/A:
It inhibits the polymerization of microtubules, hence glucose uptake is inhibited,
leading to death.
• With combination of DEC & Ivermectin, it enhances the action of the drugs. A
single dose of its combination with either DEC or ivermectin given yearly has
been used in mass programmes to suppress microfilaraemia and disease
transmission.
• More importantly, the use of single doses of two drugs administered together
(optimally albendazole with DEC or ivermectin) is 99% effective in removing
microfilariae from the blood for a full year after treatment.- WHO
22. Albendazole
S/Es:
• GI- mild and transient epigastric distress,
diarrhea, nausea,
• CNS- headache, dizziness, lassitude, and
insomnia can occur.
• It induces severe adverse reactions in hydrocele
cases due to the death of adult worms.
23. Surgery
• Large hydroceles and scrotal elephantiasis can be managed
with surgical excision.
• Correcting gross limb elephantiasis with surgery is less
successful and may necessitate multiple procedures and skin
grafting.
Prevention
• Avoidance of bites from insect vectors is usually not feasible
for residents of endemic areas, but visitors to these regions
should use insect repellent and mosquito nets.
24.
25. River blindness
• River blindness and lymphatic filariasis, caused by filarial
nematodes, are among the most important tropical diseases.
• Nearly 140 million cases exist and over 1 billion people are
at risk for infection.
• River blindness is caused by the microscopic larvae
(microfilariae) of the filarial nematode worm Onchocerca
volvulus, transmitted by blackflies.
• Adult worms can live for over a decade in nodules under the
skin and release millions of microfilariae.
• Circulating microfilariae cause persistent, debilitating itching,
severe dermatitis, and ocular lesions resulting in blindness.
