Genetic epidemiology of host predisposition microfilaraemia in human loiasis

Abstract

SummaryEvidence is accumulating from experimental and human studies that genetic factors are involved both in the control of infectious diseases and in the regulation of infection levels and clinical presentation. So far few studies have investigated the role of these genetic factors in human infection by the filarial parasite Loa loa. We present a segregation analysis on 74 nuclear families who live in the tropical rainforest of southern Cameroun and are exposed to homogeneous loiasis transmission. The results indicate that there is a genetic predisposition to be microfilaraemic and that predisposed subjects might be genetically unable to mount an efficient immune response against loiasis antigens. This individual susceptibility could explain at least in part why the prevalence of infection (microfilaraemic individuals) does not usually exceed 30% of the exposed population in hyperendemic regions. Further genetic studies, based on linkage analysis using both familial information and genetic markers, will help to identify the nature of the genetic factors predisposing to microfilaraemia.keywords loiasis, genetic epidemiology, immunity correspondence Dr A. Garcia, Institut Pierre Richet -OCCGE; BP 1500, Bouake. Côte d'Ivoire.

Loiasis with Peripheral Nerve Involvement and Spleen Lesions

“…45 It has been shown that host genetic factors, probably associated with specific immunologic responses against the Loa microfilariae, predispose a person to become microfilaremic or amicrofilaremic. 46 Such factors might explain rare occurrence of splenic involvement in loiasis in humans. As stated by Fain, histologic examinations of spleen tissue in persons infected with L. loa would shed light on this issue.…”

Microfilarial distribution of Loa loa in the human host: population dynamics and epidemiological implications

“…However, during preliminary analyses, the NBD model, when fitted to the complete observed distributions of mf densities (including zero densities), did not provide satisfactory fits, whereas the zero-truncated NBD model provided adequate fits. Thus, assuming that the zero count class may not be reliable because only y60 % of the infected population would be genetically predisposed to present with microfilaraemia (Garcia et al 1999), and that some individuals may be false-negatives (due to the lack of sensitivity of the blood film method when microfilaraemia is low), we chose the zero-truncated NBD (tNBD) model (Pichon et al 1980 ;Grenfell et al 1990).…”

Genetic polymorphisms in molecules of innate immunity and susceptibility to infection with Wuchereria bancrofti in South India

“…A recent report has shown that there could be genetic predisposition to microfilaremia and that predisposed subjects might be genetically unable to mount an efficient immune response against Loa loa antigens. 43,44 Genetic studies in severe clinical malaria using segregation analysis and linkage analysis for candidate chromosomal regions have identified specific loci in the human response to malarial infection. [45][46][47] In our study, we have identified two candidate genes, which could influence susceptibility to filarial infection.…”