It is about nematodes and the diseases caused by them.

1. Lymphatic Filariasis

2. Filariasis
• Lymphatic filariasis is a disease caused by the lymphatic dwelling nematode
(thread like) parasites
i. Wuchereria bancrofti (Wuchereriasis -90% cases)
ii. Brugia malayii
iii. Brugia timori
• Lymphatic filariasis impairs the lymphatic system and can lead to the abnormal
enlargement of body parts, causing pain, severe disability and social stigma.
• Filariasis is one of the leading causes of disability in the world, next to leprosy

3. Problem Statement
• Globally around 120 million cases are found with around 40 million people with
overt disease. (15 Million – Lymphoedema, 25 Million – Urogenital swelling)
• In India heavily infected areas are UP, Bihar, Jharkhand, Andhra Pradesh, Odisha,
Telengana, Maharashtra & West Bengal.

4. Agent Factors
Habitat
• The adult worms are found in the
lymphatic vessels and lymph nodes
of man only.
• They are long thread or hairlike,
transparent nematodes .
• Female is longer than male (10 and 4
cm respectively).
• Lifespan of the adult parasite is
about 4 to 5 years.

5. Brugia Malayi
Wuchereria bancrofti

6. Life Cycle
The parasite passes its life cycle in two hosts
• Definitive host - Humans
• Intermediate host - Mosquitoes

8. In man
• The male parasite fertilizes the female and dies.
• The gravid female discharges, as many as, 50,000 microfilariae (mf) per day, into
the circulation via lymphatics.
• The life span of microfilaria is about one year.
• They are taken up by the female culex mosquito when it feeds on human blood.
• The time required for the microfilariae to develop into adult parasite is about 1
year. Adult worm can survive upto 15 years.
• These microfilariae are all sheathed embryos

9. Microfilaria

10. In Mosquito
• Exsheathing - The ingested, sheathed, microfilariae cast off their sheaths in the
stomach of the mosquito within 1-2 hour of ingestion.
• First stage larva - Comes out and penetrate the gut wall within 6 or 12 hours and
migrate to the thoracic muscles, where they take rest and begin to grow and
develop into sausage shaped, short and thick forms.
• Second stage larvae – Larva moults and increases in length with development of
alimentary canal.
• Third stage larva – Infective stage, it migrates to proboscis of mosquito.

11. • When the infected mosquito bites the human being, the third stage infective larvae
enter the lymphatic channels, reach the inguinal, scrotal and abdominal lymphatics
and grow into adults.
• Pre-patent period – Time interval from the entrance of infective third stage
larvae in a man and the appearance of first detectable microfilariae in the
peripheral blood. Ranges from 9 months for W. bancrofti and 3 months for B.
malayii.
• Clinical Incubation period - Time interval from invasion of infective larva to the
development of clinical manifestations. Ranges from 8 to 16 months.

12. Periodicity
• The manifestations of W. bancrofti show marked nocturnal periodicity, i.e they
appear in large number at night between 10 pm and 4 am in the peripheral
circulation.
• During day time, they retire principally inside the capillaries of the lungs, heart,
kidneys.
• The mechanism of nocturnal periodicity is related to the night feeding habits of the
culex mosquito.

13. Host Factors
• Age incidence: People of all the age group are susceptible to the disease. (More in
20 to 30 years).
• Sex incidence: More among men

14. Environmental Factors
• Climate: Temperature between 25° and 35°C favors the development of parasites
in the body of the vector, culex mosquito and the relative humidity of 70 percent
favors the mosquito to survive longer.
• Drainage of sewage: Improper drainage of sewage favors the prevalence of the
disease in the area.
• Social factors - Industrialization, urbanization, migration of the people, poverty,
eruption of slums, poor sanitation, etc

15. Transmission
• The disease is transmitted from person to person by the bite of the infective female
mosquitoes.
• Culex quinquefasciatus : This breeds predominantly in organically contaminated
water like sewage, sullage water, septic tank, soakage pit drains, pit latrines, etc. It
causes bancrofti filariasis.
• Mansonia (Mansonoides) : This breeds in water containing aquatic plants such as
Pistia–stratiotes, Eichornia and Salvinia. It causes Brugian filariasis.

16. Culex Mosquito
Mansonia mosquito

17. Clinical Manifestations
Clinical Types
1. Lymphatic filariasis (filariasis caused
by parasites that are present in lymphatic
system)
2. Occult filariasis (Caused by immune
hyper responsiveness of the human host)

18. Lymphatic filariasis (Stages)
1. Asymptomatic Amicrofilaraemia – Not have symptoms nor have demonstrable
microfilariae in the blood smear. They may be infected or may not be infected.
2. Asymptomatic microfilaremia - Do not have any recognizable clinical features
(symptoms) but their (night time) blood is positive for microfilariae.

19. 3. Acute filariasis - Characterized by recurrent attacks of fever, associated with
lymphadenitis and lymphangitis. It is mainly because of
infection of the lymphatics by the adult worms.
4. Chronic filariasis - It requires about 10 to 15 years to develop fibrosis and
obstruction of lymphatics resulting in permanent damage
characterized by lymph-edema of various parts of the body,
(elephantiasis of leg, genitals, breasts, hydrocoele, lymph varix, chyluria)

20. Occult filariasis
• Also called cryptic filariasis.
• Classical manifestations are not present and microfilaria are not found in blood.
• It is believed to result from a hypersensitivity reaction of the host to microfilariae,
resulting in ‘tropical pulmonary eosinophilia’, characterized by paroxysmal
nocturnal cough, breathlessness, wheezing, miliary infiltration of the lungs ,may
be associated with lymph adenopathy and hepatospleenomegaly.

21. Filaria Survey
• This survey is done to know the magnitude of the problem and also to evaluate the
control measures.
• There are two type - Routine survey and Evaluation survey.
• The different components of filarial survey are:
i. Blood survey
ii. Clinical survey
iii. Skin and serological tests
iv. Xenodiagnosis
v. Entomological survey

22. Control Measures
1. Chemotherapy
i. Diethylcarbamazine (DEC)
ii. Filaria control in the community
2. Vector Control
i. Anti- larval measures
ii. Anti- Adult measures
iii. Personal Prophylaxis

23. Chemotherapy
Diethylcarbamazine (DEC)
• Safe & Effective
• It causes rapid disappearance of Mf from circulation.
• T/t of Bancroftian filariasis – 6 mg/kg body wt orally for 12 days.
(Full treatment – 72 mg/kg bd wt)
• T/t of Brugian filariasis – 3 to 6 mg/kg body wt orally.
(Full treatment – 36 to72 mg/kg bd wt)

24. Preventive chemotherapy
• Large scale treatment involves single dose of medicines given annually to entire at
risk population.
• It reduces the density of Mf in Blood and thus prevent the spread.
Albendazole – 400 mg
+
Ivermectin – 150-200 mcg/ kg
OR
DEC – 6 mg/kg

25. Selective treatment
• Based on detection and treatment of human carriers and filaria cases.
• DEC are given to all the positive cases.
• T/t of filariasis – 6 mg/kg body wt orally for 12 days.
(Full treatment – 72 mg/kg bd wt)
• DEC medicated salts – Common salt medicated with 1-4 g of DEC per kg.
Should be continued for 6 to 9 months.

26. Vector Control
• Vector control is beneficial when used in conjugation with mass treatment.
• Methods
i. Anti-Larval Measures – Chemical Control
Removal of Pistia Plant
Environmental Measures
ii. Anti- Adult Measures
iii. Personal Prophylaxis

27. Anti Larval Measures
• Physical Measures
i. Elimination of breeding places by providing underground drainage system for the
sanitary disposal of sewage which is the breeding place for culex mosquitoes.
ii. Removal of aquatic plants (Pistia) helps in the control of mansonoides.
(Phenoxylene–30 or Shellweed killer–D, a herbicide used to destroy acquatic
vegetation to control mansonoides larvae)
iii. Other engineering measures - Filling up of ditches, drainage of stagnant water,
Maintenance of septic tanks & soakage pits

28. Anti Larval Measures
• Chemical Measures
i. Mosquito Larvicidal oil (MLO)
Active against all preadult stages.
Expensive and less efficient in field conditions.
ii. Pyrosene oil – E
Pyrethrum based emulsifiable larvicide.
iii. Organophosphorus Larvicides
Eg. Temephos, Fenthion

29. Anti Adult Measures
• Vector mosquitoes have become resistant to DDT, HCH, dieldrin.
• Pyrethrum space spray is used.

30. Personal Prophylaxis
• Avoidance of mosquito bite (reduction of man-mosquito contact)
• Eg. Bed Nets, Repellants

31. Integrated Vector Control
• Integrated/ Combined approach is needed to control filariasis by using all the
measures and strategies in optimum combination.
1. DEC – Single dose of DEC is effective even after 2 years of treatment.
Ivermectin is also helpful in controlling the disease.
Combination of single dose of both the drugs can be useful in reducing
microfilaraemia in more than 95% cases.
2. Intensive local Hygiene of Affected limb – Reduces complications
With/ without antibiotics and antifungals

32. 3. DEC Medicated tablets/ salts – Helps in eliminating filariasis from the
community.
4. Insecticidal sprays - Used at water colleting points
Eg. Rooftop water tanks, Latrines

33. 6. Bidar district in North Karnataka, South India is a known endemic area for
filariasis. The district health officer(DHO) of Bidar is under severe pressure,
From the minister of Health and family welfare who incidentally hails from
this district itself, to control this problem. Enlist the steps that should be
taken by the district health officer of Bidar to address the problem.

34. The current strategy for filarial control is based on
1. Chemotheraphy
2. Vector control

35. Chemotherapy
a. For Bancrofti filariasis : Diethyl carbamazine (DEC) 6mg/kg/body
weight/orally for 12 days given in divided doses after meals. Total 72mg of
DEC/kg of body weight as a full treatment.
b. For brugian filariasis : Diethyl carbamazine(DEC) 3-6 mg/kg body weight
/day upto total dose of 36-72 mg of DEC/kg/body weight as full treatment.
c. Selective treatment :
Diethyl carbamazine 6mg/kg body weight daily for 12 days .and treatment must
be repeated every 2 years.

36. Chemotherapy
d. Annual Mass Drug Administration
Single annual dose of DEC 6 mg/kg body weight + Albendazole 400 mg +
Ivermectin 200 mcg/kg wt
To all eligible population in endemic area except Pregnant women, child less
than 2 & seriously ill pt

37. Vector control
1.Antilarval Measures
1.Chemical control : It includes Mosquito larvicidal oil
a. Pyreosene oil E
b .Organophosphorous larvicide ( eg, Temephos, Fenthion).
2. Removal of Pistia plant in case of Mansonia mosquito and using herbicides
such as phenoxy 30 or Shell Weed Killer D Used for aquatic destruction.

38. 3. Minor environmental measures which includes
i. Filling up of ditches and cesspools
ii. Drainage of stagnant water
iii. Adequate maintenance of septic tank

39. 2. Anti Adult measures
• Use of insecticide i.e pyrethrum as space spray