All About Lymphatic Filariasis
FILARIASIS

Filariasis is caused by several round, coiled and thread-like parasitic worms belonging to the family filaridea.These parasites aftergetting deposited on skin penetrate on their own or through the opening created by mosquito bites to reach the lymphatic system. The disease is caused by the nematode worm, either Wuchereria bancrofti or Brugia malayi and transmitted by ubiquitous mosquito species Culex quinquefasciatus and Mansonia  annulifera/M.uniformis respectively. The disease manifests often in bizarre swelling of legs, and hydrocele and is the cause of a great deal of social stigma. 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.

Brugian filariasis: Lymphadenitis (swollen and painful lymphnode) occurs episodically, most commonly affecting one inguinal lymph node at a time. The infection lasts for several days and usually heals spontaneously. The frequency of episodes may vary from 1-2 attacks per year to several attacks per month. Sometimes lymphadenitis is followed by a characteristic retrograde lymphangitis. The infection may spread to the surrounding tissues, and occasionally involves the whole thigh or entire limb. The infected lymph node may become an abscess, ulcerate, and heal with  fibrotic scarring. The acute clinical course with its complications may last from several weeks to 3 months. Characteristically, elephantiasis involves the leg below the knee but occasionally it affects the arm below the elbow. Genital lesions or chyluria (milky colour urine) do not occur in brugian filariasis.

Bancroftian filariasis: The lymphatic vessels of the male genitalia are most commonly affected in bancroftian filariasis, producing†episodic funiculitis (inflammation of the spermatic cord), epididymitis and orchitis. Adenolymphangitis of the extremities is less common.†Hydrocele is the most common sign of chronic bancroftian filariasis, followed by lymphoedema, elephantiasis and chyluria. The swelling involves the whole leg, the whole arm, the scrotum, the vulva or the breast. The fluid of hydrocele and chyluric patients may contain microfilariae, even when they are absent from the blood. Chyluria occurs intermittently and is more pronounced after a heavy meal. It is often symptomless, but some patients complain of fatigue and weight loss, resulting from loss of fat and protein.

Lymphatic filariasis (LF)

Photo Lymphatic Filariasis (LF), commonly known as elephantiasis is a disfiguring and disabling disease,†usually acquired in childhood. In the early stages, there are either no symptoms or non-specific symptoms.†Although there are no outward symptoms, the lymphatic system is damaged. This stage can last for several years. Infected persons sustain the transmission of the disease. The long term physical consequences are painful swollen limbs (lymphoedema or elephantiasis). Hydrocele in males is also common in endemic areas.

Due to damaged lymphatic system, patients with lymphoedema have frequent attacks of infection causing high fever and severe pain. Patients may be bed-ridden for several days and normal†routine activities become difficult.†Such attacks not only cause acute physical suffering but also directly impede the earning capacity of the individual.†Lymphatic filariasis is estimated to be one of the leading causes of disability worldwide.†Elimination of the disease is an important tool for poverty alleviation and economic development.


Filaria vectors

C.quinquefasciatus is the vector of W.bancrofti in the mainland. C.quinquefasciatus breeds in association with human habitations and is the domestic pest mosquitoes, preferring polluted waters, such as sewage and sullage water collections including cess pools, cess pits, drains and septic tanks. In the absence of such type of water collections, they can breed in comparatively clean water collections also.

The eggs are laid in rafts containing 150-40 eggs each depending on quality and quantity of blood meal taken. At the optimum temperature of 250C to 300C, the eggs hatch within 24 to 48 hours. The youngest stage is the first instar larva which moults to subsequent instars each within 24-48 hours at optimum temperature. There are four instars in the larval stages, and all the instars are voracious eaters, taking anything and everything of microscopic size into the buccal cavity by instant vibration of its feeding brushes. They are mainly bottom feeders but may feed from the surface also.

The IV instar at the end of its stage gives rise to a comma shaped pupa, which lasts upto 24-48 hours at optimal condition. Pupae do not feed but are very active, respiring through its pair of breathing trumpets. The pupa emerges into an adult mosquito, through a longitudinal slit formed between the two trumpets. The entire cycle from egg to emergence of adult is completed in 10-14 days.

Transmission of Lymphatic Filariasis

The adult produces millions of very small immature larvae known as microfilariae, which circulate in the peripheral blood with marked nocturnal periodicity. The worms usually live and produce microfilariae for 5-8 years.



Adult Filarial Worms (Macrofilariae)†inhabiting†lymphatic system of man

Lymphatic filariasis is transmitted through mosquito bites.

The persons having circulating microfilariae are outwardly healthy but transmit the infection†to others through mosquitoes.

The persons with chronic filarial swellings suffer severely from the disease but no longer transmit the infection.

In India, 99.4% of the cases are caused by the species - Wuchereria bancrofti whereas Brugia malayi is responsible for 0.6% of the problem.

In the adult stage, filarial worms live in the vessels of the lymphatic system. Lymphatic system is the network of lymph nodes and lymph vessels that maintains the fluid balance between the tissues and the blood which is an essential element of the body's immune defense system.

LIFE CYCLE OF FILARIA PARASITE

Photo Man is the definitive host i.e. where the mature adult male and female†parasites†mate and produce microfilariae whereas the mosquito is the intermediate host. The adult parasites are usually found in the lymphatic system of man. They give birth to as many as 50,000 microfilariae per day, which find their way into blood circulation. The life span of microfilaria is not exactly known which preferably may survive up to a couple of months.

The parasite cycle in the mosquito begins when the microfilariae are picked up by the vector mosquitoes during their feeding on the infected person (microfilaria carrier). The microfilaria in mosquito develops into three stages and under optimum conditions of temperature and humidity; the duration of the cycle in the mosquito (extensive incubation period) is about 10-14 days. When the infective mosquito feeds on other human host, the infective larvae are deposited at the†site of mosquito bite from where the infective larvae get into lymphatic system. In the human host, the infective larvae develop into adult male and female worms. The adult worms survive for about 5-8 years or sometimes as long as 15 years or more.








Magnitude of disease

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.†In 1709, Clarke called elephantoid legs in Cochin as Malabar legs.

The discovery of microfilariae (mf) in the peripheral blood was made first by Lewis in 1872 in Calcutta (Kolkata).

Indigenous cases have been reported from about 250 districts in 20 states/Union Territories.

The North-Western States/UTs namely Jammu & Kashmir, Himachal Pradesh, Punjab, Haryana, Chandigarh, Rajasthan, Delhi and Uttaranchal and North-Eastern States namely Sikkim, Arunachal†Pradesh, Nagaland, Meghalaya, Mizoram, Manipur and Tripura are known to be free from indigenously acquired filarial infection.

Cases of filariasis have been recorded from Andhra Pradesh, Assam, Bihar, Chhattisgarh, Goa, Jharkhand, Karnataka, Gujarat, Kerala, Madhya Pradesh, Maharashtra, Orissa, Tamil Nadu, Uttar Pradesh, West Bengal, Pondicherry, Andaman & Nicobar Islands, Daman & Diu, Dadra & Nagar Haveli and Lakshadweep.

FILARIA ENDEMIC DISTRICTS

Endemic district 250
(in 20 States/UTs)
Population: 600 Million


National Filaria Control Programme (NFCP)

After pilot project in Orissa from 1949 to 1954, the National Filaria Control Programme (NFCP) was launched in the country in 1955 with the objective of delimiting the problem, to undertake control measures in endemic areas and to train personnel to man the programme. The main control measures were mass DEC administration, antilarval measures in urban areas and indoor residual spray in rural areas. The NFCP set-up and population protected are given in the table below:

Population protected under NFCP and the set-up as on 01-03-2002

Sl.No. State/UTs Population Protected (in million) Filaria Control Units Survey Units Filaria Clinics
I II III IV V VI
1. Andhra Pradesh 6.03 29 2 5
2. Assam 0.31 1 1 0
3. Bihar 8.40 35 2 38
4. Chhatisgarh Nil 0 0 0
5. Goa 0.37 4 0 6
6. Gujarat 3.91 9 0 7
7. Jharkhand        
8. Karnataka 0.72 6 1 19
9. Kerala 4.45 16 2 9
10. Madhya Pradesh 0.74 9 3 8
11. Maharashtra 6.52 16 6 10
12. Orissa 2.54 15 2 15
13. Tamil Nadu 9.44 21 1 42
14. Uttar Pradesh 7.33 29 2 34
15. West Bengal 1.53 10 4 3
16. Pondicherry 0.54 2 0 0
17. A&N Islands 0.06 1 1 1
18. Daman & Diu 0.03 2 0 2
19. Lakshadweep 0.01 1 0 0
20. Dadra & N' Haveli Nil 0 0 0

Strategy

  • Recurrent anti-larval measures at weekly intervals.
  • Environmental methods including source reduction by filling ditches, pits, low lying areas, deweeding, desilting, etc.
  • Biological control of mosquito breeding through larvivorous fish.
  • Anti-parasitic measures through 'detection' and 'treatment' of microfilaria carriers and disease person with DEC by Filaria Clinics in towns covered under the programme.
Revised Strategy

Annual Mass Drug Administration†with single dose of DEC was taken up as a pilot project covering 41 million population in 1996-97 and extended to 74 million population. This strategy was to be continued for 5 years or more to the population excluding children below two years, pregnant women and seriously ill persons in affected areas to interrupt transmission of disease.

Interruption of transmission of filariasis by Annual MDA for 5 years or more to the population except:

- children below 2 years
- pregnant women
- seriously ill persons
  (DEC + Albendazole in selected distt & DEC in other distt)
Morbidity Management

- Home based management of lymphoedema cases and
- up-scaling of hydrocele operations in the identified CHCs / District hospitals/ medical colleges.

National Goal

The National Health Policy 2002 aims at Elimination of Lymphatic Filariasis by 2015.


Morbidity Management

Sl No. States/UTs 2004 round 2005 round 2006 round 2007 round 2008 round 2009 round 2010 round 2011 round 2012 round 2013 round
1 Andhra Pradesh 84.78 84.33 89.66 89.13 91.85 91.96 92.50 92.74 93.30 92.59
2 Assam 25.42 42.94 67.33 78.32 81.34 ND 81.62 76.75 79.02 78.67
3 Bihar 81.64 77.82 79.77 77.23 ND 77.91 78.61 ND 85.38 YD
4 Chhattisgarh 84.17 82.80 ND 93.65 91.30 91.53 92.99 90.06 ND 89.18
5 Goa 97.92 95.33 97.17 97.83 96.44 95.37 94.63 96.21 MDA stopped MDA stopped
6 Gujarat 45.47 98.23 97.69 92.11 93.25 97.63 98.33 97.66 99.04 99.38
7 Jharkhand 42.25 74.16 72.75 79.03 84.62 85.99 63.64 86.53 87.88 ND
8 Karnataka 85.22 89.31 90.20 89.67 90.53 89.30 91.46 91.81 93.84 92.70
9 Kerala 86.10 90.15 ND 92.19 93.67 77.81 81.91 89.62 80.90 73.33
10 Madhya Pradesh 73.74 79.29 88.01 88.48 90.14 87.59 90.74 89.27 87.88 ND
11 Maharashtra 78.68 86.48 90.15 89.53 91.05 89.51 89.38 89.28 89.30 91.21
12 Orissa 90.11 90.29 88.93 88.47 89.67 89.66 90.63 90.55 ND 91.1
13 Tamil Nadu 95.18 ND ND 77.22 88.80 94.13 ND 93.58 94.76(4 dist.) MDA stopped
14 Uttar Pradesh 66.40 71.03 75.97 79.87 81.67 ND 81.04 80.45 83.15 70.41
15 West Bengal 39.58 54.01 ND 76.63 77.79 86.93 ND 79.23 80.51 YD
16 A & N Islands 85.85 88.31 93.17 98.73 94.10 91.40 77.12 90.15 90.06 88.93
17 D & Nagar Haveli 91.13 98.26 94.93 94.16 96.67 95.84 96.20 98.51 96.88 95.83
18 Daman & Diu 94.96 73.23 87.17 93.27 91.85 91.56 92.04 90.89 MDA stopped MDA stopped
19 Lakshadweep 79.99 84.60 83.16 81.81 82.63 83.86 80.09 73.94 ND 94.22
20 Pondicherry 97.76 96.63 ND 96.30 97.01 96.02 96.92 97.14 MDA stopped MDA stopped
  Total 72.42 76.65 81.86 82.91 86.42 86.69 84.50 87.92 86.13 86.09
ND : Not Done | YD : Yet to do | RN: Report Not received

For any scientific publication, if this quoated or used for any analysis purposes, Dte.NVBDCP prior permission must be sought.

Trend of Average Microfilaria rates (%) in the State since 2004

Sl. No. States/UTs 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
1 Andhra Pradesh 1.36 0.74 0.69 0.26 0.38 0.45 0.35 0.21 0.20 0.22
2 Assam ND 0.04 0.19 1.46 0.88 0.81 1.06 0.17 0.19 0.15
3 Bihar 1.50 2.15 1.38 0.68 ND 1.07 0.94 ND 1.15 ND
4 Chhattisgarh ND 1.96 ND 0.61 0.45 0.54 0.40 0.10 0.10 0.08
5 Goa 0.11 0.04 0.02 0.08 0.01 0.00 0.01 0.00 MDA stopped MDA stopped
6 Gujarat 0.22 0.84 0.84 0.42 0.83 0.92 0.46 0.52 0.24 0.31
7 Jharkhand ND 0.84 1.40 1.34 1.10 1.11 0.82 0.63 NR ND
8 Karnataka 1.87 0.84 0.69 1.15 1.07 0.93 0.89 0.83 0.65 0.60
9 Kerala 0.68 0.50 0.67 0.65 0.29 0.39 0.17 0.14 0.21 0.15
10 Madhya Pradesh 0.83 0.40 0.38 0.70 0.36 0.40 0.19 0.23 0.09 ND
11 Maharashtra 1.13 1.45 1.13 0.83 0.35 0.46 0.53 0.51 0.43 0.46
12 Orissa 2.60 2.37 1.11 0.99 0.74 0.69 0.40 0.43 0.34 0.34
13 Tamil Nadu 0.04 0.38 0.39 0.29 0.15 0.12 0.07 0.09 0.17 ND
14 Uttar Pradesh 1.77 1.01 0.81 0.32 0.41 ND 0.28 0.24 0.38 0.17
15 West Bengal 4.74 4.10 2.72 2.83 0.89 0.48 0.44 0.55 0.70 ND
16 A&N Islands 1.4 0.09 0.15 0.34 0.19 0.46 0.10 0.12 0.17 0.14
17 D & N Haveli 1.96 2.01 2.91 3.47 1.82 1.23 0.95 1.79 0.71 0.54
18 Daman & Diu 0.47 0.14 0.27 0.09 0.07 0.07 0.06 0.07 MDA stopped MDA stopped
19 Lakshadweep 1.19 0.09 0.07 0.02 0.27 0.00 0.00 ND ND ND
20 Pondicherry 0.42 0.50 0.15 0.06 0.03 0.00 0.00 0.00 MDA stopped MDA stopped
  National Average 1.24 1.02 0.98 0.64 0.53 0.65 0.41 0.37 0.41 0.29
ND : Not Done || NR: Not Reported
For any scientific publication, if this quoated or used for any analysis purposes, Dte.NVBDCP prior permission must be sought.


STRATEGY FOR ELIMINCATION OF LYMPHATIC FILARIASIS

The strategy for achieving the goal of elimination is by Annual Mass Drug Administration of Anti Filarial Drugs (DEC+Albendazole) for 5 years or more to the population excluding children below two years, pregnant women and seriously ill persons in affected areas to interrupt transmission of disease.

Home based management of cases who already have the disease and hydrocelectomy operations in identified CHCs and hospitals.



Mass Drug Administration


Lymphatic Filariasis Elimination Goal

The Government of India is signatory to the World Health Assembly Resolution in 1997 for Global Elimination of Lymphatic Filariasis. The National Health Policy (2002) envisages elimination of lymphatic filariasis in India by 2015.


Strategy for Elimination of Lymphatic Filariasis

  • Annual Mass Drug Administration (MDA) of single dose of DEC (Diethylcarbamazine citrate) and Albendazole for 5 years or more to the eligible population (except pregnant women, children below 2 years of age and seriously ill persons) to interrupt transmission of the disease.
  • Home based management of lymphoedema cases and up-scaling of hydrocele operations in identified CHCs/ District hospitals /medical colleges.
mf&coverage

Progress and Achievement
In pursuit of the goals, the Government of India launched nationwide MDA in 2004 in endemic areas as well as home based morbidity management, scaling up hydrocelectomies in hospitals and CHCs. During the year 2004, only 202 districts could be covered with coverage rate of 72.6%. The number of districts was upscaled and in 2007 all the 250 known LF endemic districts were brought under MDA. The policy decision to implement global strategy of co-administration of DEC with Albendazole during MDA was approved by National Task Force on Elimination of Lymphatic Filariasis under the Chairmanship of DGHS. The population coverage during MDA has improved from 73% in 2004 to 83% in 2013 (Prov.) which has resulted in the overall reduction of microfilaria rate from 1.24% in 2004 to 0.29% in 2013 (Prov.).

Capacity building has improved the performance of various functionaries. The initiative was taken to involve senior faculties from various medical colleges during 2005-2007. A total of 544 faculty members belonging to medicine, community medicine, pharmacology, microbiology and paediatrics were trained from 79 medical colleges. Subsequently trainings were imparted in state and approximately about 1 million health personnels including Medical Officers, Paramedics, Drug Distributors, Lab. Technicians, etc are trained annually on MDA and Morbidity management.

Intensive social mobilization during MDA, have been carried out by various states/ UTs involving political/ opinion leaders, decision makers, local leaders and community.

Validation through Transmission Assessment Survey (TAS)
All the districts have completed more than 5 rounds of MDA by the end of 2013, and are required to be evaluated to decide whether to stop or continue MDA. As per WHO guidelines-2011, the districts having observed minimum five rounds of MDA with more than 65% coverage against total population at risk in implementation unit (population of district covered under MDA) are to be subjected for Transmission Assessment Survey (TAS) using Immuno-chromatographic test (ICT) for presence of circulating antigenaemia in children born after initiation of MDA to know the current infection.
  • During July 2012, WHO conducted a Regional Workshop on Capacity Building on TAS at Puducherry (India) for all Member countries of SEAR.
  • Four National level Trainerís Training Workshops at Pune, Bhubaneswar, Chennai and Bangalore were organized with WHO support. In these workshops, a total of 139 state and district level officials were trained.
  • During 2012-13, 4 districts, during 2013-14, 7 districts have successfully completed TAS.
  • During 2014-15, TAS is expected to be carried out in 96 districts. Out of these, 55 districts have already completed additional Mf survey and few are in process of completing TAS. Majority are waiting for procurement and supply of ICT cards which is manufactured by only one company i.e. Allere (Binax), USA.
  • The progress on ELF is being appraised independently by ICMR to suggest immediate measures for improvement so as to achieve the goal of elimination. The issue of tackling hot spot areas and also the migratory populations is expected to be addressed by the experts during the appraisal.
Morbidity Management and Disability Alleviation
Morbidity Management is another pillar of strategy for ELF and states/UTs were advised on up-scaling home based morbidity management of Lymphoedema cases and Hydrocele operations. The process involved updating the line-listing of Lymphoedema & Hydrocele cases in the districts. Demonstration and training on simple foot hygiene to affected persons and motivate them for self practice. Motivate for surgical intervention to hydrocele cases. The updated report from LF endemic states/UTs indicated 8 lakh Lymphoedema and 4 lakh hydrocele cases.

Since 2004, the states/UTs have reported 110842 hydrocele operations. Different states have initiated management of Lymphodema cases through demonstrating home based foot hygiene method to patients at local levels.


MORBIDITY MANAGEMENT