The document discusses filariasis, an infection caused by nematodes and transmitted through mosquito bites. It causes lymphangitis, lymphadenitis and elephantiasis. Around 893 million people worldwide are at risk. India accounts for 67% of the endemic population in Southeast Asia. Clinical manifestations range from asymptomatic microfilaremia to lymphedema and elephantiasis. Diagnosis involves blood smears and serology. Control relies on annual mass drug administration with diethylcarbamazine and albendazole, as well as integrated vector control measures.

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Filariasis Dr. Animesh Gupta

2. Filariasis
Dr. Animesh Gupta
MD, FDM, FAGE
Associate Professor
Dept. of Community Medicine, NMCH, Sasaram

3. Introduction
Infection caused by three closely related
nematodes (W. bancrofti, B. malayi & B. timori) &
transmitted to man by bite of infective mosquitos &
clinically characterized by-
Lymphangitis, lymphadenitis, elephantiasis of genitals,
legs & arms or
Pulmonary esonophilia or
Filaria arthritis
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Filariasis Dr. Animesh Gupta

4. Burden
893 million people in 49 countries worldwide remain
threatened by lymphatic filariasis.
630 million people are at risk of lymphatic filariasis
infection in 16 States and 5 Union Territories in India
India contributes about 67% of endemic population
and 81% of the disease burden in the South East Asia
Region.
Heavily infected areas are found in UP, Bihar, Andhra
Pradesh, Orissa, Tamil Nadu, Kerala, and Gujarat.
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5. Epidemiological determinants
Agent factors-
Definitive host - Man
Intermediate host- Mosquito
Agents of lymphatic filariasis-
W. bancrofti, B. malayi & B. timori
Agents of non-lymphatic filariasis-
Onchocerca volvulus, Loa Loa, Tetrapetalonema
perstans, T. streptocerca, Mansonella ozzardi
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6. Periodicity
The Mf. Of W. bancrofti and B. malayi has a
nocturnal periodicity.
Maximum density of Mf in blood is reported between
10 pm and 2 am.
Reservoir of Infection
Man with circulating microfilaria
For Brugia - Monkeys, cats, dogs
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7. Life cycle
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Filariasis Dr. Animesh Gupta

8. Host factors
 Age
Affect all ages, Infection rate more in 20-30 years
 Sex-
Male > Female
 Migration- spreads infection
 Immunity- After many years of exposures
 Social factors
Urbanization, industrialization, illiteracy, poverty, poor
sanitation
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9. Environmental Factors
▪ Climate
✓ Temp. 22-380C
✓ Relative humidity- 70%
▪ Drainage
▪ Associated with bad drainage
▪ Town planning
✓ Inadequate sewage disposal, lack of town planning
▪ Common breeding places of mosquito
✓ cesspools, soakage pits, ill-maintained drains, septic
tanks, burrow pits 5/15/2020
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Filariasis Dr. Animesh Gupta

10. Vectors of lymphatic filariasis
▪ Vectors
✓ Culex, Anopheles & Aedes for
W. Bancrofti
✓ Mansonia, Anopheles for
Brugia species
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Filariasis Dr. Animesh Gupta

11. Anopheles Aedes Culex
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12. Mode of transmission
 Bite of infected mosquito vector
▪ Parasites deposited at puncture site
▪ Passes through puncture skin or may penetrate skin &
finally reach lymphatic system
 Dynamics depends upon man-mosquito contact
(infective biting rate)
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13. Incubation Period
▪ Clinical incubation period —
✓ 8 to 16 months
▪ Pre-patent period
✓ Time interval between inoculation of infective larva &
first appearance of detectable Mf.
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Filariasis Dr. Animesh Gupta

14. Clinical manifestations
1. Lymphatic Filariasis
i. Asymptomatic amicrofilaraemia
ii. Asymptomatic microfilaraemia
iii. Stage of acute manifestations
iv. Stage of chronic obstructive lesions
2. Occult filariasis
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15. Clinical manifestations …
I. Asymptomatic amicrofilaraemia
✓ No Mf. or C/F
✓ Exposure to infective larva
II. Asymptomatic microfilaraemia
✓ Asymptomatic, Mf. Present
✓ Imp. Source of infection in community
✓ Detected by night blood examination
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Filariasis Dr. Animesh Gupta

16. Clinical manifestations …
III. Stage of acute manifestations
✓ Acute inflammation of lymph glands & vessels
✓ Filarial fever, lymphangitis, lymphadenitis,
lymphoedema of various parts, epididymo-orchitis.
IV. Stage of chronic obstructive lesions
✓ Develops 10-15 years from onset of first acute attack
✓ Fibrosis & obstruction of lymphatic vessels
✓ Bancroftian filariasis – hydrocele, elephantasis, chyluria,
elephantasis of legs, arms, scrotum, penis, vulva, breast
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Filariasis Dr. Animesh Gupta

17. Clinical manifestations…
❑Occult Filariasis
✓ Classical manifestations are not present and Mf are
not found in blood.
✓ Due to result from a hypersensitivity reaction to
filarial antigens derived from Mf. e.g. tropical
pulmonary esonophilia.
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18. Elephantiasis
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19. Lymphoedema management
 Early detection of lymphoedema
 Care of skin- washing & drying the affected limb
 Preventing and treating entry lesions and
 Providing lymph drainage by elevating the limb &
exercising.
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Filariasis Dr. Animesh Gupta

21. Lymphoedema management…
 Treatment for uncomplicated acute dermato-
lymphangioadenitis (ADLA):
Analgesic – paracetamol – 1 gm , 3-4 times a day
Oral antibiotic – amoxicillin/ erythromycin – 8 days
Clean limb with antiseptic
Check for any wounds/ cuts/ abcess
Do not give anti filarial treatment
Home management like drinking plenty of water, rest,
elevation of limb, cooling and washing the limb.
Follow up after 2 days at home.
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22. Lymphoedema management…
 Management of severe ADLA
IV Benzyl penicillin (Penicillin G) – 5 million units 3 times a day
OR
IM Procaine benzyl penicillin – 5 million units 2 times a day.
Then give
Oral phenoxymethylpenicillin (Penicillin V) – 750mg (1.2
million units) to 1 gm (1.6million units) 3 times a day
Total duration of treatment 8 days
Give analgesic/antipyretic such as paracetamol
Don’t give anti filarial medicine
Hydrocele management - Hydrocelectomy
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23. Why DEC not given in ADLA?
 In early stages of lymphedema, DEC may be helpful since
there may be an active filarial infection and its use might
prevent further lymphatic damage through its
macrofilaricidal action.
 The use of this drug in chronic and advanced cases of
lymphedema is not substantiated since it is now known that
there is neither microfilaremia nor live adult parasites
during these stages.
 Recent studies indicate that DEC has no role either in the
treatment or prevention of ADLA attacks occurring in cases
of lymphedema, which are caused by bacterial infections
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24. Filaria survey
o Mass blood survey
o Clinical survey
o Serological tests
o Xenodiagnosis
o Entomological survey
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25. Filaria Survey -Mass blood survey
▪ The thick film
✓ 20 cu. mm of blood by deep finger prick (8.30 pm to 12 mid-night)
✓ Dehaemoglobinised, stained, dried & examined Mf. under low
power
▪ Membrane filter concentration (MFC) methods
✓ Most sensitive method
✓ Detect low density microfilaraemia by filtering large volume of
blood
▪ DEC provocation test
✓ Administer 100 mg of DEC orally
✓ Blood examined 1 hour after administration of DEC
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Filariasis Dr. Animesh Gupta

26. Filaria Survey
▪ Clinical survey
✓ Examine for clinical manifestations of filariasis
▪ Serological tests
✓ Detect Antibodies to Mf. & adults using
immunofluorescent & CF techniques
✓ Can’t distinguish between past & present infection
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27. Filaria Survey…
▪ Xenodiagnosis
✓ Mosquitoes allow to feed on the patient
✓ Dissection of mosquito 2 weeks later
▪ Entomological survey
✓ Collection of mosquitoes
✓ Dissection of female vector - detect developmental
forms of the parasite
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28. Assessment of Filaria Control Programme
▪ Clinical parameters
✓ Incidence of acute manifestations
✓ Prevalence of chronic manifestations
▪ Entomological parameters
✓ Vector density,
✓ Percentage of mosquito positives,
✓ Annual biting rate,
✓ Types of larval breeding places
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29. Assessment of filaria control programme
Parasitological parameters
o Microfilaria rate - % of persons showing Mf in blood
o Filarial endemicity rate - % of persons examined
showing Mf in their blood or disease or both
o Microfilarial density - no. of Mf per unit volume of
blood
o Average infestation rate – Average no. of Mf per
positive slide. It indicates prevalence of
microfilaraemia in the population
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30. Control Measures
 Chemotherapy
 Vector control
o Chemotherapy - Diethylcarbamazine (DEC)
✓ For Bancroftian filariasis – 6mg/kg/day orally for 12 days
✓ For Brugian filariasis – 3-6mg/kg/day for 6-12 days
▪ Toxic reactions
▪ Due to drug - Headache, nausea, vomiting, dizziness
▪ Due to allergic reactions of Mf or adult worms - Fever,
local inflammations, orchitis, lymphadenitis, transient
lymphoedema
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31. Chemotherapy-
Filaria control in the community
▪ Mass therapy (Annually 4-6 years)
✓ In highly endemic areas – DEC - 6mg/kg bw, single dose +
albendazole (400 mg)
▪ Selective treatment
✓ Low endemicity areas – usual dose of treatment
✓ DEC – repeated at specified interval usually after 2 years
▪ DEC medicated salt
✓ Common salt medicated with 1-4gm of DEC/kg in
endemic areas for 6-9 months
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32. Vector control measures
❑ Anti-larval measures
❑ Anti-adult measures
❑ Protection against mosquito bite
❑ Integrated approach
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33. Thank you 5/15/2020
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Filariasis Dr. Animesh Gupta