Is mass drug administration against lymphatic filariasis required in urban settings? The experience in Kano, Nigeria
Date
2017-10
Journal Title
Journal ISSN
Volume Title
Publisher
PLOS Negleted Tropical Diseases
Abstract
Background
The Global Programme to Eliminate Lymphatic Filariasis (GPELF), launched in 2000, has
the target of eliminating the disease as a public health problem by the year 2020. The strategy
adopted is mass drug administration (MDA) to all eligible individuals in endemic communities
and the implementation of measures to reduce the morbidity of those suffering from
chronic disease. Success has been recorded in many rural endemic communities in which
elimination efforts have centered. However, implementation has been challenging in several
urban African cities. The large cities of West Africa, exemplified in Nigeria in Kano are challenging
for LF elimination program because reaching 65% therapeutic coverage during
MDA is difficult. There is therefore a need to define a strategy which could complement
MDA. Thus, in Kano State, Nigeria, while LF MDA had reached 33 of the 44 Local Government
Areas (LGAs) there remained eleven `urban' LGAs which had not been covered by
MDA. Given the challenges of achieving at least 65% coverage during MDA implementation
over several years in order to achieve elimination, it may be challenging to eliminate LF in
such settings. In order to plan the LF control activities, this study was undertaken to confirm
the LF infection prevalence in the human and mosquito populations in three urban LGAs.
Methods
The prevalence of circulating filarial antigen (CFA) of Wuchereria bancrofti was assessed by
an immuno-chromatography test (ICT) in 981 people in three urban LGAs of Kano state,
Nigeria. Mosquitoes were collected over a period of 4 months from May to August 2015
using exit traps, gravid traps and pyrethrum knock-down spray sheet collections (PSC) indifferent households. A proportion of mosquitoes were analyzed forW. bancrofti, using dissection,
loop-mediated isothermal amplification (LAMP) assay and conventional polymerase
chain reaction (PCR).
Results
The results showed that none of the 981 subjects (constituted of <21% of children 5±10
years old) tested had detectable levels of CFA in their blood. Entomological results showed
that An. gambiae s.l. hadW. bancrofti DNA detectable in pools in Kano;W. bancrofti DNA
was detected in between 0.96% and 6.78% and to a lesser extent in Culex mosquitoes
where DNA was detected at rates of between 0.19% and 0.64%. DNA analysis showed that
An. coluzzii constituted 9.9% of the collected mosquitoes and the remaining 90.1% of the
mosquitoes were Culex mosquitoes.
Conclusion
Despite detection ofW. bancrofti DNA within mosquito specimens collected in three Kano
urban LGAs, we were not able to find a subject with detectable level of CFA. Together with
other evidence suggesting that LF transmission in urban areas in West Africa may not be of
significant importance, the Federal Ministry of Health advised that two rounds of MDA be
undertaken in the urban areas of Kano. It is recommended that the prevalence ofW. bancrofti
infection in the human and mosquito populations be re-assessed after a couple of
years.
Description
Keywords
Eliminate, Lymphatic, Filariasis, Mass Drug Administration
Citation
Pam DD, de Souza DK, D'Souza S, Opoku M, Sanda S, Nazaradden I, et al. (2017) Is mass drug administration against lymphatic filariasis required in urban settings? The experience in Kano, Nigeria. PLoS Negl Trop Dis 11(10): e0006004.