1. Lymphatic filariasis, also known as elephantiasis, is a neglected tropical disease caused by filarial parasites transmitted to humans by mosquitoes. It affects over 120 million people globally. 2. Infection occurs when filarial parasites are transmitted to humans through the bites of infected mosquitoes. This leads to damage of the lymphatic system over time, causing lymphedema, elephantiasis, and hydrocele in up to 40 million people. 3. In India, over 1 billion people are at risk of infection, with areas of high endemicity including states like Bihar, UP, and Orissa. The national control program employs mass drug administration of DEC or iverme

1. LYMPHATIC FILARIASIS
1
BRIG DR HEMANT KUMAR
PROF &HOD

2. 2

3.  Filariasis has been a major public
health problem in India next only to
malaria.
 The disease was recorded in India as
early as 6th century B.C. by the famous
Indian physician, Susruta in his
book Susruta Samhita. In 7th century
A.D.,
 Madhavakara described signs and
symptoms of the disease in his treatise
'Madhava Nidhana' which hold good
even today. 3

4. Contd…
In 1709, Clarke called
elephantoid legs in Cochin
as Malabar legs.
The discovery of microfilariae
(MF) in the peripheralblood
was made first by Lewis in
1872 in Calcutta(Kolkata)
4

5. Filariasis is caused by several
round, coiled and thread-like
parasitic worms belonging to the
family filaridea.
These parasites after getting
deposited on skin penetrate on their
own or through the opening
created by mosquito bites to reach
the lymphatic system.
5

6. Based on pathogenicity and
habitat it classified into:
1) Lymphatic filariasis
2) Subcutaneous
filariasis
3) Serous cavity
filariasis
4) Zoonotic filariasis 6

7. LYMPHATIC
FILARIASIS
7

8. Lymphatic Filariasis, commonly
known as elephantiasis, is a
neglected tropical disease.
Infection occurs when filarial
parasites are transmitted to
humans through mosquitoes.
Infection is usually acquired in
childhood causing damage to the
lymphatic system
8

9. The painful and profoundly disfiguring
visible manifestations of the disease,
lymphedema, elephantiasis and
scrotal swelling occur later in life
and can lead to permanent
disability.
These patients are not only physically
disabled, but suffer mental, social
and financial losses contributing to
stigma and poverty.
9

10. 10

11. It is endemic in many tropical &
subtropical countries like Africa, Asia,
Western Pacific and parts of America.
11

12. More than 1.4 billion
people are at risk, and
approximately 65%
reside in WHO’s South
East Asia Region.
Over 120 million people
are currently infected,
and about 40 million
disfigured and
incapacitated by the
disease.
12

13. 1.4 billion people live in
areas with risk of infection
Out of them, 120
million are infected
and need treatment
Out of them, 40 million people
are with overt disease
15 million people
with lymph-
oedema
25 million men
with uro-genital
swelling mainly
scrotal hydrocele
13

14. 14

15. INDIAN
SCENARIO
15

16. The overall microfilaria rate has reduced
from 1.24% in 2004 to 0.29% in 2015 at
the national level.
Out of 255 districts, 203 have reported
overall microfilaria rate of less than 1%.
Out of remaining 52 districts, 31 need
high priority as these districts have been
persistently reporting microfilaria rate
above 1%,
16

17. 17

18. 18
Heavily infected areas include UP, Bihar,
Jharkhand, Andhra Pradesh, Orissa, TN,
Kerala and Gujarat.

19. Epidemiology
19

20. AGENT FACTORS
 There are at least 8 species of filarial
parasites that are specific to man.
 They are Wuchereria bancrofti, Brugia
malayi, Brugia timori, Onchocerca
volvulus, Loa loa, T perstans, T
streptocerca, Mansonella ozzardi
 Out of these, the first 3 cause lymphatic
filariasis.
20

21. PERIODICITY
 Both the microfilaria(Mf) of W. bancrofti
and B. malayi occurring in India display
nocturnal periodicity.
 The maximum density is reported between
10pm to 2am.
 This is a biological adaption to the
nocturnal biting habits of the vector
mosquitoes.
21

22. LIFE CYCLE
22

23. DEFINITIVE HOST- MAN,
INTERMEDIATE HOST- MOSQUITO
 The adult worms (macrofilaria) are found in the
lymphatic system of man, where they may survive
for 15 yrs or more.
 During their lifespan, after mating, female worms
(viviparous) give birth to 50,000 immature
microfilariae(mf) per day into the blood
circulation via lymphatics. They may survive up
to a year or more.
 Some of these microfilariae may be ingested by
the mosquitoes during their blood meal.
23

24. STAGES IN THE MOSQUITO
1) EX-SHEATHING- The larva comes out of the
sheath in which it was enclosed in stomach of
the mosquito.
2) FIRST STAGE LARVA -The larva penetrates
the stomach wall of the mosquito, and migrate
thoracic muscles where it develops into a short
thick form
3) SECOND STAGE LARVA- The larva moults
and increase in length
4) THIRD STAGE LARVA (INFECTIVE)-The
larva moults and develops into a long thin form
which migrates to the proboscis of the mosquito.
The mosquito is said to be infected.
24

25. 25

26. 26

27. RESERVOIR OF INFECTION
Although filarial infection occurs in
animals, human filariasis is not usually a
zoonosis.
 In man, the source of infection is a
person with circulating Mf in peripheral
blood.
 In filarial disease (late obstructive
stages), Mf are not found in the blood.
27

28. VECTORS OF LYMPHATIC
FILARIASIS
i. Culex - vector for Bancroftian filariasis
ii. Mansonia - vector for Brugian filariasis
 Culex breeds in polluted water
 Mansonia is associated with certain
aquatic plants (such as Pistia stratiotes)
28
Culex
Mansonia

29. HOST FACTORS
Man is a natural host.
a) AGE : All ages are susceptible to infection.
 The infection rates rise with age up to 20-30 yrs
and then level off
b) GENDER
 In most endemic areas, Mf rate is higher in men
c) MIGRATION
 Migration led to the extension of filariasis into
non-endemic areas
29

30. D) IMMUNITY
• develops only after years of exposure
E) SOCIAL FACTORS
 Lymphatic filariasis is associated with
poor sanitation, urbanization,
migration of people, etc.
30

31. ENVIRONMENTAL FACTORS
a) CLIMATE –
 It influences the breeding of mosquitoes, their longevity
and the development of parasite in insect vector.(22-38
°C , RH - 70%
b) DRAINAGE –
 Vectors breed profusely in polluted water.
c) TOWN PLANNING –
 Inadequate sewage disposal and lack of town planning
have aggravated the problems of filariasis in India.The
common breeding places are open ditches, septic tanks,
ill-maintained drains.
31

32. 32

33. 33

34. 34

35. 35

36. 36

37. 37

38. 38

39. 39

40. 40

41. 41

42. 42

43. FILARIA SURVEY
 5-7% of the population for routine surveys
and 20% for evaluation studies.
 It consists of-
1) Mass blood survey
2) Clinical survey
3) Serological tests
4) Xenodiagnosis
5) Entomological survey
43

44. DEC PROVOCATION TEST
 Mf can be induced to appear in blood in
the daytime by administering DEC100mg
orally.
 Mf begin to reach their peak within
15minutes and begin to decrease 2hrs
later.
44

45. 2) Clinical Survey
 People are examined for clinical
manifestations of filariasis.
3) Serological tests
 To detect antibodies to Mf and adults
using immunoflorescent and complement
fixing techniques.
 But , CANNOT DISTINGUISH between
past and present infection, and heavy and
light parasite loads.
45

46. 4) Xenodiagnosis
 Mosquitoes are allowed to feed on the
patient, and then dissected 2weeks later.
5) Entomological survey
 It consists of:
i. general mosquito collection from houses
ii. dissection of female vector species for
detection of developmental forms of the
parasite
iii. Study of the extent and type of breeding
places.
46

47. ASSESSMENT OF FILARIAL
CONTROL PROGRAMMES
It can be assessed using:
1) Clinical parameters
2) Parasitological parameters
3) Entomological parameters
47

48. 1) CLINICAL PARAMETERS
Incidence of acute manifestations and
prevalence of chronic manifestations are
measured.
2) PARASITOLOGICAL PARAMETERS
i. Microfilaria rate- It is the % of people
showing Mf in their peripheral blood in
the sample population.
48

49. ii. Filarial endemicity rate- It is the % of
people examined showing microfilariae
in their blood, or disease manifestation
or both.
iii. Microfilarial density- It is the no. of
Mf per unit volume of blood in samples
from individual people.It indicates the
intensity of infection
iv. Average infestation rate- It is the
average no. of Mf per positive slide.It
indicates the prevalence of
microfilaraemia in the population.
49

50. ENTOMOLOGICAL PARAMETERS
They comprise
i. Vector density per 10 man-hour catch
ii. % of mosquitoes positive for all stages of
development
iii. % of mosquitoes positive for infective
larvae
iv. Annual biting rate
v. Types of larval breeding places
50

51. Control Measures
51

52. The current strategy is based on-
i. Chemotheraphy
ii. Vector control
52

53. CHEMOTHERAPY
1) DEC
2) Filaria control
in the
community
a) Mass Therapy
b) Selective
Treatment
c) DEC-
medicated salt
3) Ivermectin
53

54. 1) DEC
 It is safe and effective.
 Given in divided doses after meals
 Rapidly absorbed
 Reaches peak blood levels in 1-2hrs
 Rapidly excreted
54
Filariasis Dose
1) Bancroftian filariasis 6mg/kg body weight per day
orally for 12 days
2) Brugian filariasis 3-6mg/kg body weight per day
orally for 12 days

55. 2) Filaria control in the community
2) Filaria control
in the community
a) Mass Therapy
b) Selective
Treatment
c) DEC-medicated
salt
55

56. Mass therapy-
 DEC is given to everyone in the
community irrespective of whether they
have microfilaraemia, disease manifestation
or no signs of infection; except children
under 2yrs, pregnant women and seriously
ill patients.
 Dose: DEC 6mg/kg body weight
 Indicated in highly endemic areas
56

57. Selective treatment
 DEC given only to those who are Mf
positive.More suitable in low endemicity
areas.Dose: 6mg DEC per kg body weight
daily for 12 doses
 In endemic areas, it should be repeated
every 2yrs
57

58. Vector Control
 Vector control is beneficial when used in
conjunction with mass treatment.
 The most important step is to reduce the
target mosquito population to stop or
reduce the transmission.
 It consists of:
i. Anti-larval measures
ii. Anti-adult measures
iii. Personal prophylaxis
58

59. NATIONAL FILARIA CONTROL
PROGRAMME
 It is operational since 1955
 In June 1978, it was merged with malaria
scheme.Filaria control strategy includes
i. vector control through anti-larval
operations
ii. Source reduction
iii. Detection and treatment of
microfilaria carriers
iv. Morbidity management
59

60. 60