Epidemiology and control of lymphatic filariasis in Burkina Faso
This thesis presents the work divided in three main areas: 1) the distribution of
Lymphatic Filariasis caused by Wuchereria bancrofti and the non-pathogenic filarial
parasite Mansonella perstans; 2) the implementation of a public health programme to
eliminate LF describing the activities and discussing the impact of the programme, and
3) the assessment of the cost of the NPELF.
This study was the first to provide countrywide epidemiological data on W.
bancrofti and M. perstans infections in Burkina Faso as well as in some other West
African countries. All the 55 health districts were mapped using immunochromatographic
card tests for filarial antigenaemia detection. All the 102 sampled villages were positive
except one. The prevalence ranged from 2% to 74% and the overall prevalence was
29.2%. W. bancroft; microfilaraemia baseline in sentinel sites showed an overall
prevalence of 8.2% and the average mean density was 1108mf/ml in positive subjects.
Children under 5 years presented 0.6% W. bancrofti microfilaraemia prevalence. The
urban distribution of W. bancrofti showed a lower prevalence for antigenaemia (2.3%)
and microfilaraemia (0.7%). Hydrocoele prevalence in males 15 years and above was
7.2% while lymphoedema was found in 0.6% of the 13 492 surveyed individuals. M.
perstans has also been found to be widely distributed in the country with an overall
prevalence of 5.9%.
The impact of the onchocerciasis control programme activities using the
distribution of ivermectin alone for 6 and 14 years in two different sites in Burkina Faso
was also studied. It was concluded that 6-year treatment with ivermectin alone might
have significantly reduced the prevalence of W. bancrofti whilst it appears that up to 14
years annual or twice-annual treatment with ivermectin may have stopped W. bancrofti
transmission. These findings have implications for many areas of Africa where
onchocerciasis and LF are co-endemic and the APOC programme has created
sustained ivermectin distribution programmes.
This thesis documented the impact of 2 to 5 rounds of mass drug administration
using albendazole and ivermectin following the implementation of the national
programme to eliminate lymphatic filariasis. Although, yearly treatment coverage (69% to
77%) never reached the recommended 80% coverage of total population a significant
decline in community microfilaraemia prevalence (up to 95%) and density (up to 98%)
has been observed in all sentinel sites except one. In general, there were no significant
changes in M. perstans prevalence and density after 2 to 5 annual treatments.
Monitoring results showed that reported and checked coverage were largely consistent
in the rural and semi-urban districts but not in the urban settings. In addition, there was
relative low prevalence of side effects following treatments. Lymphatic filariasis
transmission knowledge was poor and the main reason for not taking the drugs was
The cost analysis of the programme demonstrated that the start-up financial cost
per person treated was US$ 0.11 as the programme is using the existing health system
including community volunteers.
The studies carried out in this thesis suggest that the GPELF recommended
strategy is effective; however, used by and within a national public health system of a
"developing" country elimination may need more time than the anticipated four to six
years. The required improvement of the social mobilisation component remains a
challenge for the success of the programme, especially in urban settings.