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. 2011 Oct;5(10):e1329.
doi: 10.1371/journal.pntd.0001329. Epub 2011 Oct 11.

Epidemiology of concomitant infection due to Loa loa and Mansonella perstans in Gabon

Jean Paul Akue  1 , Dieudonné Nkoghe, Cindy Padilla, Ghislain Moussavou, Hubert Moukana, Roger Antoine Mbou, Benjamin Ollomo, Eric Maurice Leroy
Affiliations

Epidemiology of concomitant infection due to Loa loa and Mansonella perstans in Gabon

Jean Paul Akue et al. PLoS Negl Trop Dis. 2011 Oct.

Abstract

Background: The filarial parasites Loa loa and Mansonnella perstans are endemic in the central and western African forest block. Loa loa is pathogenic and represents a major obstacle to the control of co-endemic filariae because its treatment can cause fatal complications such as encephalitis.

Methodology/principal findings: 4392 individuals aged over 15 years were studied both by direct examination and a concentration technique. The overall prevalence rates were 22.4% for Loa loa microfilaremia, 10.2% for M. perstans microfilaremia, and 3.2% for mixed infection. The prevalence of both filariae was higher in the forest ecosystem than in savannah and lakeland (p<0.0001). The intensity of microfilariae (mf) was also higher in the forest ecosystem for both parasites. The prevalence and intensity of microfilaria were both influenced by age and gender. Correlations were found between the prevalence and intensity of Loa loa microfilariae (r = 0.215 p = 0.036), and between the prevalence of Loa loa and the prevalence of individuals with microfilaria >8000 mf/ml (r = 0.624; p<0.0001) and microfilariae >30 000 mf/ml (r = 0.319, p = 0.002). In contrast, the prevalence of pruritis and Calabar swellings correlated negatively with the prevalence of Loa loa microfilaria (r = -0.219, p = 0.032; r = -0.220; p = 0.031, respectively). Pruritis, Calabar swellings and eye worm were not associated with L. loa mf intensity (r = -0.144, p = 0.162; r-0.061, p = 0.558; and r = 0.051, p = 0.624, respectively), or with the prevalence or intensity of M. perstans microfilariae.

Conclusions/significance: This map of the distribution of filariae in Gabon should prove helpful for control programs. Our findings confirm the spatial uniformity of the relationship between parasitological indices. Clinical manifestations point to a relationship between filariae and allergy.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Map of Gabon with administrative regions and the locations of surveyed villages (red circles).
Strictly georeferenced and generated by MAPINFO. The ecosystems are represented in different colours.
Figure 2
Figure 2. Distribution of Loa loa (A) and Mansonella perstans (B) in Gabon according to the geographic region.
Figure 3
Figure 3. Distribution of L. loa in Gabon in the different ecosystems (A) (Prevalence rates of Loa loa are shown within the corresponding ecosystem), and villages (B).
Figure 4
Figure 4. Intensity of Loa loa microfilaremia in Gabon according to age and gender.
Figure 5
Figure 5. Correlation between the prevalence and intensity of Loa loa microfilaremia.
A. Total studied population. B. In individuals with >8000 Loa microfilariae/ml. C. In individuals with >30 000 Loa microfilariae/ml.
Figure 6
Figure 6. Correlation between the prevalence of Loa loa microfilaremia and clinical symptoms.
A. Pruritus B. Calabar swellings. C. Eye worm.
See this image and copyright information in PMC

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