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Lymphatic filariasis control in Tanga Region, Tanzania: status after eight rounds of mass drug administration.

Simonsen PE, Derua YA, Magesa SM, Pedersen EM, Stensgaard AS, Malecela MN, Kisinza WN - Parasit Vectors (2014)

Bottom Line: Since then, the current project has monitored the effect in communities and schools in rural areas of Tanga District.LF burdens gradually decreased when moving to districts further inland and with higher altitudes.Monitoring should continue to guide the programme to ensure that the current major achievements will ultimately lead to successful LF elimination.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, 1870, Frederiksberg C, Denmark. pesi@sund.ku.dk.

ABSTRACT

Background: Lymphatic filariasis (LF) control started in Tanga Region of Tanzania in 2004, with annual ivermectin/albendazole mass drug administration (MDA). Since then, the current project has monitored the effect in communities and schools in rural areas of Tanga District. In 2013, after 8 rounds of MDA, spot check surveys were added in the other 7 districts of Tanga Region, to assess the regional LF status.

Methods: LF vector and transmission surveillance, and human cross sectional surveys in communities and schools, continued in Tanga District as previously reported. In each of the other 7 districts, 2-3 spot check sites were selected and about 200 schoolchildren were examined for circulating filarial antigens (CFA). At 1-2 of the sites in each district, additional about 200 community volunteers were examined for CFA and chronic LF disease, and the CFA positives were re-examined for microfilariae (mf).

Results: The downward trend in LF transmission and human infection previously reported for Tanga District continued, with prevalences after MDA 8 reaching 15.5% and 3.5% for CFA and mf in communities (decrease by 75.5% and 89.6% from baseline) and 2.3% for CFA in schoolchildren (decrease by 90.9% from baseline). Surprisingly, the prevalence of chronic LF morbidity after MDA 8 was less than half of baseline records. No infective vector mosquitoes were detected after MDA 7. Spot checks in the other districts after MDA 8 showed relatively high LF burdens in the coastal districts. LF burdens gradually decreased when moving to districts further inland and with higher altitudes.

Conclusion: LF was still widespread in many parts of Tanga Region after MDA 8, in particular in the coastal areas. This calls for intensified control, which should include increased MDA treatment coverage, strengthening of bed net usage, and more male focus in LF health information dissemination. The low LF burdens observed in some inland districts suggest that MDA in these could be stepped down to provide more resources for upscale of control in the coastal areas. Monitoring should continue to guide the programme to ensure that the current major achievements will ultimately lead to successful LF elimination.

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Prevalence of circulating filarial antigens (A) and microfilaraemia (B) in the rural study communities in Tanga District during surveys 1 and 7–9. Data are from individuals aged ≥10 years from two hamlets of Kirare (Mtambuuni, Mashine), one hamlet of Kiomoni (Mabavu) and one hamlet of Kisimatui (Majengo). Bar = prevalence in Kirare at the pre-MDA survey in 2004; Orange line = prevalence in Kirare in survey 7–9; Green line = prevalence in Kiomoni in survey 7–9; Blue line = prevalence in Kisimatui in survey 7–9. In the pre-MDA survey all individuals were examined for mf, and volunteers from mosquito collection houses only were examined for CFA by ELISA. In surveys 7–9 all individuals were first examined for CFA with ICT cards, and those positive were examined for mf. Vertical stippled lines indicate rounds of MDA.
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Fig2: Prevalence of circulating filarial antigens (A) and microfilaraemia (B) in the rural study communities in Tanga District during surveys 1 and 7–9. Data are from individuals aged ≥10 years from two hamlets of Kirare (Mtambuuni, Mashine), one hamlet of Kiomoni (Mabavu) and one hamlet of Kisimatui (Majengo). Bar = prevalence in Kirare at the pre-MDA survey in 2004; Orange line = prevalence in Kirare in survey 7–9; Green line = prevalence in Kiomoni in survey 7–9; Blue line = prevalence in Kisimatui in survey 7–9. In the pre-MDA survey all individuals were examined for mf, and volunteers from mosquito collection houses only were examined for CFA by ELISA. In surveys 7–9 all individuals were first examined for CFA with ICT cards, and those positive were examined for mf. Vertical stippled lines indicate rounds of MDA.

Mentions: The LF infection results from surveys 7, 8 and 9 in Kirare, Kiomoni and Kisimatui villages are shown in Table 2, and these results are compared to those from Kirare in 2004 in Figure 2. Both CFA and mf prevalences were considerably lower in the later surveys than in Kirare in 2004, and on average for the three villages reached 15.5% and 3.5%, respectively during survey 9 (decrease by 75.5% and 89.6%, respectively, compared to the baseline level in Kirare). The decrease in CFA prevalence between survey 7 and 9 was statistically significant in all three villages, and for the villages combined it was highly significant between each individual survey (p =0.009 between survey 7 and 8; p <0.001 between survey 8 and 9). The decrease in mf prevalence and mf GMI among all examined between survey 7 and 9 was also obvious for the three villages combined, although a slight increase was noted in Kirare between survey 8 and 9 (statistics cannot be computed due to the method of assessing these indices, see Methods).Table 2


Lymphatic filariasis control in Tanga Region, Tanzania: status after eight rounds of mass drug administration.

Simonsen PE, Derua YA, Magesa SM, Pedersen EM, Stensgaard AS, Malecela MN, Kisinza WN - Parasit Vectors (2014)

Prevalence of circulating filarial antigens (A) and microfilaraemia (B) in the rural study communities in Tanga District during surveys 1 and 7–9. Data are from individuals aged ≥10 years from two hamlets of Kirare (Mtambuuni, Mashine), one hamlet of Kiomoni (Mabavu) and one hamlet of Kisimatui (Majengo). Bar = prevalence in Kirare at the pre-MDA survey in 2004; Orange line = prevalence in Kirare in survey 7–9; Green line = prevalence in Kiomoni in survey 7–9; Blue line = prevalence in Kisimatui in survey 7–9. In the pre-MDA survey all individuals were examined for mf, and volunteers from mosquito collection houses only were examined for CFA by ELISA. In surveys 7–9 all individuals were first examined for CFA with ICT cards, and those positive were examined for mf. Vertical stippled lines indicate rounds of MDA.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4233105&req=5

Fig2: Prevalence of circulating filarial antigens (A) and microfilaraemia (B) in the rural study communities in Tanga District during surveys 1 and 7–9. Data are from individuals aged ≥10 years from two hamlets of Kirare (Mtambuuni, Mashine), one hamlet of Kiomoni (Mabavu) and one hamlet of Kisimatui (Majengo). Bar = prevalence in Kirare at the pre-MDA survey in 2004; Orange line = prevalence in Kirare in survey 7–9; Green line = prevalence in Kiomoni in survey 7–9; Blue line = prevalence in Kisimatui in survey 7–9. In the pre-MDA survey all individuals were examined for mf, and volunteers from mosquito collection houses only were examined for CFA by ELISA. In surveys 7–9 all individuals were first examined for CFA with ICT cards, and those positive were examined for mf. Vertical stippled lines indicate rounds of MDA.
Mentions: The LF infection results from surveys 7, 8 and 9 in Kirare, Kiomoni and Kisimatui villages are shown in Table 2, and these results are compared to those from Kirare in 2004 in Figure 2. Both CFA and mf prevalences were considerably lower in the later surveys than in Kirare in 2004, and on average for the three villages reached 15.5% and 3.5%, respectively during survey 9 (decrease by 75.5% and 89.6%, respectively, compared to the baseline level in Kirare). The decrease in CFA prevalence between survey 7 and 9 was statistically significant in all three villages, and for the villages combined it was highly significant between each individual survey (p =0.009 between survey 7 and 8; p <0.001 between survey 8 and 9). The decrease in mf prevalence and mf GMI among all examined between survey 7 and 9 was also obvious for the three villages combined, although a slight increase was noted in Kirare between survey 8 and 9 (statistics cannot be computed due to the method of assessing these indices, see Methods).Table 2

Bottom Line: Since then, the current project has monitored the effect in communities and schools in rural areas of Tanga District.LF burdens gradually decreased when moving to districts further inland and with higher altitudes.Monitoring should continue to guide the programme to ensure that the current major achievements will ultimately lead to successful LF elimination.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, 1870, Frederiksberg C, Denmark. pesi@sund.ku.dk.

ABSTRACT

Background: Lymphatic filariasis (LF) control started in Tanga Region of Tanzania in 2004, with annual ivermectin/albendazole mass drug administration (MDA). Since then, the current project has monitored the effect in communities and schools in rural areas of Tanga District. In 2013, after 8 rounds of MDA, spot check surveys were added in the other 7 districts of Tanga Region, to assess the regional LF status.

Methods: LF vector and transmission surveillance, and human cross sectional surveys in communities and schools, continued in Tanga District as previously reported. In each of the other 7 districts, 2-3 spot check sites were selected and about 200 schoolchildren were examined for circulating filarial antigens (CFA). At 1-2 of the sites in each district, additional about 200 community volunteers were examined for CFA and chronic LF disease, and the CFA positives were re-examined for microfilariae (mf).

Results: The downward trend in LF transmission and human infection previously reported for Tanga District continued, with prevalences after MDA 8 reaching 15.5% and 3.5% for CFA and mf in communities (decrease by 75.5% and 89.6% from baseline) and 2.3% for CFA in schoolchildren (decrease by 90.9% from baseline). Surprisingly, the prevalence of chronic LF morbidity after MDA 8 was less than half of baseline records. No infective vector mosquitoes were detected after MDA 7. Spot checks in the other districts after MDA 8 showed relatively high LF burdens in the coastal districts. LF burdens gradually decreased when moving to districts further inland and with higher altitudes.

Conclusion: LF was still widespread in many parts of Tanga Region after MDA 8, in particular in the coastal areas. This calls for intensified control, which should include increased MDA treatment coverage, strengthening of bed net usage, and more male focus in LF health information dissemination. The low LF burdens observed in some inland districts suggest that MDA in these could be stepped down to provide more resources for upscale of control in the coastal areas. Monitoring should continue to guide the programme to ensure that the current major achievements will ultimately lead to successful LF elimination.

Show MeSH
Related in: MedlinePlus