Epidemiology of Concomitant Infection Due to Loa loa and Mansonella perstans in Gabon

Abstract

BackgroundThe 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 Findings4392 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/SignificanceThis 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.

Associations Between Helminth Infections, Plasmodium falciparum Parasite Carriage and Antibody Responses to Sexual and Asexual Stage Malarial Antigens

“…This village is endemic for S. haematobium, Loa loa, and Mansonella perstans as well as for various geohelminths. [25][26][27] Malaria is also endemic in the area with P. falciparum reported as dominant species. 28 Inclusion of participants in the study was not random but based on their willingness to participate.…”

Filaria zoogeography in Africa: ecology, competitive exclusion, and public health relevance

“…Recent surveys and detailed maps confirm the contrasting epidemiology of L. loa and O. volvulus [41] and, as far as the DRC is concerned, a distinct absence of W. bancrofti has been noted in areas where L. loa is highly endemic [42][43][44][45]. Likewise, this inverse relationship can be extended to tropical forest regions of Gabon and Cameroon where the prevalence of W. bancrofti and O. volvulus is relatively low [46][47][48][49]. Interestingly, however, high L. loa and M. perstans prevalences are found to coexist geographically [48][49][50], suggesting that particular filariae are sympatric.…”

“…Likewise, this inverse relationship can be extended to tropical forest regions of Gabon and Cameroon where the prevalence of W. bancrofti and O. volvulus is relatively low [46][47][48][49]. Interestingly, however, high L. loa and M. perstans prevalences are found to coexist geographically [48][49][50], suggesting that particular filariae are sympatric. Their success and ability to coexist in the same area may be attributed to vector periodicity and host partitioning: for instance, the diurnal Chrysops spp.…”

Age-dependent prevalence of Loa loa amicrofilaremia and microfilaremia status as defined by two markers: microfilaria and specific IgG4

“…An estimated 10 millions individuals are thought to harbour the parasite (Sasa, 1976;Akue et al, 2011;Zouré et al, 2011) and in some regions, the loiasis is the second cause of hospital consultation after malaria (Boulestiex and Carme, 1986). Several clinical symptoms varying from mild to severe have been documented in L. loa infection (Nutman et al, 1988;Klion et al, 1991;Akue, 2011). The treatment available (diethylcarbamazine citrate and Ivermectine) are mostly active on circulating microfilariae (Richard-Lenoble et al, 1988).…”