**5. Filariasis control initiatives in India**

LF is considered one of the NTDs that cause huge deformities and disabilities on the society. India contributes the major burden globally. The initial effort was to establish the concept of controlling the disease. In the concept of its elimination on the line of global initiative, India has made significant progress. In India, LF is caused by two roundworm nematode parasites *W. bancrofti* and *B. malayi* and is transmitted by the mosquito vectors *Culex quinquefasciatus*, *Mansonia annulifera* and *M. uniformis. B. malayi* which contributes to a negligible proportion is present in Kerala, Andhra Pradesh, Odisha, Madhya Pradesh, Assam and West Bengal. In general, Bihar state has the highest endemicity while Goa the lowest [12]. Here a detailed recent account has been enumerated.

#### **5.1 National filaria control programme**

After the pilot project in Orissa from 1949 to 1954 and based on its assessment, In India, the National Filaria Control Programme (NFCP) was launched in 1955. The main objective was to control the problem, have effective planning for control measures in endemic areas and also to train health personnel to strengthen the programme. The immediate control measures were mass drug administration of DEC, antilarval measures in urban areas and indoor residual spray in the rural areas. The programme was assessed four times by the assessment committees in 1961, 1971, 1982 and 1995, respectively. In 1961, the assessment revealed the failure of mass DEC administration due to community reluctance and ineffectiveness of insecticidal indoor spray due to the high resistance in the vector, and therefore as per recommendation of assessment committee, recurrent antilarval measures, establishment of new control units in endemic urban areas and provision of disposal of sewage and sullage were instituted. In 1971, the assessment committee recommended the detection and treatment of Mf cases with DEC at a dose of 6 mg/kg per day for 12 days and antilarval measures. Again in 1982, the assessment committee recommended extension of NFCP to rural areas through primary health-care system with 100% central assistance [5]. The fourth assessment in 1995 recommended to launch a project on the eradication of *B. malayi*, integrated vector control for all vector borne diseases, adoption of model bye-laws for effective control of vectors in domestic situation and fresh delimitation survey in rural areas.

#### **5.2 Diethylcarbamazine-medicated salt**

Mass treatment with DEC-medicated salt at community level has been used in a number of places as a control measure for lymphatic filariasis. In India this regimen was initiated as pilot projects in 1968–1969 in Uttar Pradesh and Andhra Pradesh. This showed very encouraging results. A recent review from 11 communities from China, India, Taiwan, Tanzania and Haiti on DEC-medicated salt in high-endemic districts and also in *B. malayi* areas opined high impact of this strategy which may be an end game for LF elimination. In 1976–1977 the distribution of 0.1% DEC-medicated salt was distributed in a population of 25,000 in Lakshadweep Island. There was an 80% reduction on Mf rate and 90% on circulating Mf after 1 year. Similarly, 0.2% salt conducted in Karaikal, Puducherry, showed 98% reduction on Mf [13]. A recent study on DEC-fortified salt (0.2%) and iodine for the elimination of diurnally sub-periodic *W. bancrofti* in Andaman and Nicobar Island showed encouraging results. Community coverage of >90% resulted in the reduction of Mf rate from 2.27 to 0.14% in the DEC-salt-arm (<1% in all the villages) and 1.26 to 0.74% (>1% in 4 out of 14 villages) in the MDA-arm. Antigen prevalence reduced to zero from 1.0 (DEC-salt + MDA-arm) to 6.3% (MDA-arm) in 2–3 years old, 1.2 to 3.6% from 2.9 in the DEC-salt-arm and 4.5% in the MDA-arm among 6–7 years old [14]. However, studies have indicated that it has to be used in specific situations [15].

#### **5.3 Improved diagnosis of lymphatic filariasis**

There are several methods for the diagnosis of LF. The microfilariae can be detected directly through blood smear examination, membrane filtration method, DEC-provocative test and quantitative buffy coat methods. Other methods are polymerase chain reaction (PCR), ultrasonography, lymphoscintigraphy (LSG), X-ray diagnosis and also hematology [16].

Circulating microfilariae can be detected by examining thick smears (20–60 μl) of finger-prick blood. Based on the periodicity of the microfilariae, blood samples are collected either at night hours or during daytime (in Andaman Nicobar Islands where *W. bancrofti* is transmitted by Aedes). The method is cheap and feasible at individual and community levels for mapping the endemicity of lymphatic filariasis and monitoring of MDA activities [17]. It has been observed that blood smear preparation on the micro-slides is a cumbersome process. Alternatively though not recommended in the programme, the finger-pricked whole blood (50 μl) can be collected in citrate–phosphate-dextrose (CPD) solution charged (25 μl) in 1.5 ml microfuge tubes. The tubes can be kept in +4°C freezer and can be examined within 48 hours. CPD-mixed whole blood (20 μl) are drawn by micropipette and placed in a micro-slide. The blood is smeared on the micro-slide and examined under10× microscope when the blood is wet. In positive samples, live moving parasites can be seen easily. This is a very simple method and can be easily executed. If needed, the dry smears can be stained for future reference.

The Filariasis Test Strip (FTS) of Alere (now Abbott Diagnostics) is a rapid diagnostic test recommended for mapping, monitoring and transmission assessment surveys (TAS) for the qualitative detection of *W. bancrofti* antigen in human blood samples. Now, the FTS has replaced the Binax Now filariasis immunochromatographic test (ICT), which also detects the same antigen in blood samples. The Brugia Rapid point-of-care cassette test (BRT) manufactured by Reszon Diagnostics is recommended for use during TAS to detect IgG4 antibody against *Brugia spp.* in human blood samples [17].

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**6. Discussion**

*A New Outlook in Lymphatic Filariasis Elimination in India*

**5.4 Mass drug administration its coverage and impact**

In India, in the initial process of ELF, a district-level survey in 2000 revealed that of the 289 districts, 257 were endemic for LF [18]. In 2002, the National Health Policy had set the interim goal for the elimination of this disease in India by the year 2015 [19]. To support GPELF by raising funds and helping in various other ways, a global coalition was forged among 43 different donors constituting the Global Alliance to Eliminate Lymphatic Filariasis (GAELF). One of the partners GlaxoSmithKline has volunteered to supply the total quantity of albendazole tablets required to eliminate LF globally, free of cost [20]. The DEC tablets needed for the

In 2004, the elimination of LF programme was launched on June 5 in 202 districts of 15 states and 5 union territories. However, based on the experience of MDA in June 2004 when high temperature prevailed in most of the places, the date of 'National Filaria Day' was changed to November 11 in consultation with the states. To promote and create awareness on LF, this date was observed as 'National Filaria Day' since then. In the beginning, DEC was introduced under the MDA programme and, in 2007 ALB, was added with DEC as a global strategy. Gradually 255 districts were brought under MDA, and the assessment in 2013 indicated that 203 districts out of 255 had reported microfilaria rate <1% [21–24]. The number of districts reporting Mf rate below 1% increased to 222 and in 53 districts where MDA was withdrawn as halt in transmission was indicated. A transmission assessment survey (TAS) was qualified for 68 districts. The remaining districts were struggling to achieve the goal, making the MDA twice in a year [25].

TAS is a tool designed to know whether or not transmission is interrupted by MDA. In case, the transmission has been interrupted; the prevalence of circulating antegenaemia among children born after initiation of MDA should be below critical threshold, so that the transmission of disease is no longer sustainable and future generation will be free from this disease. Before TAS, it should be ensured that all implementation units (IUs) have had at least five effective MDAs with >65% of population coverage and each of sentinel, spot and additional spot sites had

China and the Republic of Korea have declared to have eliminated lymphatic filariasis as a public health problem in 2007 and 2008, respectively. According to the WHO, 81 endemic countries were reduced to 72 requiring MDA. Out of the 72 countries, 15 have been declared to have eliminated LF as a public health problem. These countries are Togo, Egypt, Maldives, Sri Lanka, Thailand, American Samoa, Cambodia, Cook Islands, Marshall Islands, Niue, Palau, Tonga, Vanuatu, Viet Nam

Another six countries, namely, Malawi, Brazil, Bangladesh, Kiribati and Lao PDR have stopped MDA and are under post-MDA surveillance. Recent report indicates that two countries Kiribati and Yemen have eliminated LF [17]. Out of the remaining, 5 have not yet started MDA, 32 have fully scaled up MDA and 14 thought

Now India is on a critical phase for ELF facing serious challenges. The main challenge is the implementation of MDA with improved actual drug compliance so

programme in India is being supplied by the central government [19].

*DOI: http://dx.doi.org/10.5772/intechopen.92454*

**5.5 Transmission assessment survey**

achieved <1% Mf rate [26].

and Wallis and Futuna [26].

to be started and MDA is yet to be scaled up fully [26].

*Parasitology and Microbiology Research*

**5.2 Diethylcarbamazine-medicated salt**

has to be used in specific situations [15].

X-ray diagnosis and also hematology [16].

*Brugia spp.* in human blood samples [17].

**5.3 Improved diagnosis of lymphatic filariasis**

Mass treatment with DEC-medicated salt at community level has been used in a number of places as a control measure for lymphatic filariasis. In India this regimen was initiated as pilot projects in 1968–1969 in Uttar Pradesh and Andhra Pradesh. This showed very encouraging results. A recent review from 11 communities from China, India, Taiwan, Tanzania and Haiti on DEC-medicated salt in high-endemic districts and also in *B. malayi* areas opined high impact of this strategy which may be an end game for LF elimination. In 1976–1977 the distribution of 0.1% DEC-medicated salt was distributed in a population of 25,000 in Lakshadweep Island. There was an 80% reduction on Mf rate and 90% on circulating Mf after 1 year. Similarly, 0.2% salt conducted in Karaikal, Puducherry, showed 98% reduction on Mf [13]. A recent study on DEC-fortified salt (0.2%) and iodine for the elimination of diurnally sub-periodic *W. bancrofti* in Andaman and Nicobar Island showed encouraging results. Community coverage of >90% resulted in the reduction of Mf rate from 2.27 to 0.14% in the DEC-salt-arm (<1% in all the villages) and 1.26 to 0.74% (>1% in 4 out of 14 villages) in the MDA-arm. Antigen prevalence reduced to zero from 1.0 (DEC-salt + MDA-arm) to 6.3% (MDA-arm) in 2–3 years old, 1.2 to 3.6% from 2.9 in the DEC-salt-arm and 4.5% in the MDA-arm among 6–7 years old [14]. However, studies have indicated that it

There are several methods for the diagnosis of LF. The microfilariae can be detected directly through blood smear examination, membrane filtration method, DEC-provocative test and quantitative buffy coat methods. Other methods are polymerase chain reaction (PCR), ultrasonography, lymphoscintigraphy (LSG),

Circulating microfilariae can be detected by examining thick smears (20–60 μl) of finger-prick blood. Based on the periodicity of the microfilariae, blood samples are collected either at night hours or during daytime (in Andaman Nicobar Islands where *W. bancrofti* is transmitted by Aedes). The method is cheap and feasible at individual and community levels for mapping the endemicity of lymphatic filariasis and monitoring of MDA activities [17]. It has been observed that blood smear preparation on the micro-slides is a cumbersome process. Alternatively though not recommended in the programme, the finger-pricked whole blood (50 μl) can be collected in citrate–phosphate-dextrose (CPD) solution charged (25 μl) in 1.5 ml microfuge tubes. The tubes can be kept in +4°C freezer and can be examined within 48 hours. CPD-mixed whole blood (20 μl) are drawn by micropipette and placed in a micro-slide. The blood is smeared on the micro-slide and examined under10× microscope when the blood is wet. In positive samples, live moving parasites can be seen easily. This is a very simple method and can be easily executed. If needed, the dry smears can be stained for

The Filariasis Test Strip (FTS) of Alere (now Abbott Diagnostics) is a rapid diagnostic test recommended for mapping, monitoring and transmission assessment surveys (TAS) for the qualitative detection of *W. bancrofti* antigen in human blood samples. Now, the FTS has replaced the Binax Now filariasis immunochromatographic test (ICT), which also detects the same antigen in blood samples. The Brugia Rapid point-of-care cassette test (BRT) manufactured by Reszon Diagnostics is recommended for use during TAS to detect IgG4 antibody against

**326**

future reference.

#### **5.4 Mass drug administration its coverage and impact**

In India, in the initial process of ELF, a district-level survey in 2000 revealed that of the 289 districts, 257 were endemic for LF [18]. In 2002, the National Health Policy had set the interim goal for the elimination of this disease in India by the year 2015 [19]. To support GPELF by raising funds and helping in various other ways, a global coalition was forged among 43 different donors constituting the Global Alliance to Eliminate Lymphatic Filariasis (GAELF). One of the partners GlaxoSmithKline has volunteered to supply the total quantity of albendazole tablets required to eliminate LF globally, free of cost [20]. The DEC tablets needed for the programme in India is being supplied by the central government [19].

In 2004, the elimination of LF programme was launched on June 5 in 202 districts of 15 states and 5 union territories. However, based on the experience of MDA in June 2004 when high temperature prevailed in most of the places, the date of 'National Filaria Day' was changed to November 11 in consultation with the states. To promote and create awareness on LF, this date was observed as 'National Filaria Day' since then. In the beginning, DEC was introduced under the MDA programme and, in 2007 ALB, was added with DEC as a global strategy. Gradually 255 districts were brought under MDA, and the assessment in 2013 indicated that 203 districts out of 255 had reported microfilaria rate <1% [21–24]. The number of districts reporting Mf rate below 1% increased to 222 and in 53 districts where MDA was withdrawn as halt in transmission was indicated. A transmission assessment survey (TAS) was qualified for 68 districts. The remaining districts were struggling to achieve the goal, making the MDA twice in a year [25].

#### **5.5 Transmission assessment survey**

TAS is a tool designed to know whether or not transmission is interrupted by MDA. In case, the transmission has been interrupted; the prevalence of circulating antegenaemia among children born after initiation of MDA should be below critical threshold, so that the transmission of disease is no longer sustainable and future generation will be free from this disease. Before TAS, it should be ensured that all implementation units (IUs) have had at least five effective MDAs with >65% of population coverage and each of sentinel, spot and additional spot sites had achieved <1% Mf rate [26].

China and the Republic of Korea have declared to have eliminated lymphatic filariasis as a public health problem in 2007 and 2008, respectively. According to the WHO, 81 endemic countries were reduced to 72 requiring MDA. Out of the 72 countries, 15 have been declared to have eliminated LF as a public health problem. These countries are Togo, Egypt, Maldives, Sri Lanka, Thailand, American Samoa, Cambodia, Cook Islands, Marshall Islands, Niue, Palau, Tonga, Vanuatu, Viet Nam and Wallis and Futuna [26].

Another six countries, namely, Malawi, Brazil, Bangladesh, Kiribati and Lao PDR have stopped MDA and are under post-MDA surveillance. Recent report indicates that two countries Kiribati and Yemen have eliminated LF [17]. Out of the remaining, 5 have not yet started MDA, 32 have fully scaled up MDA and 14 thought to be started and MDA is yet to be scaled up fully [26].
