Clustering of filarial infection in an age-graded study: genetic, household and environmental influences
A statistical method that analyses correlation structures in families to delineate the contribution of genetic, household and environmental factors on clustering of infection, has been applied to data collected in an area endemic for brugian filariasis in South Sulawesi, Indonesia. Infection was assessed both by microfilaraemia and by anti-filarial IgG4. The results confirmed earlier findings that genetic factors play an important role in clustering of infection. When clustering of infection was analysed in children (<10 years of age) and adults (>20 years of age) separately, it was found that the genetic factors influence clustering of infection in children more profoundly than environmental or household effects. In contrast, genetic factors could not fully explain the clustering of infection seen in adults, which seemed to be mainly determined by household and environmental effects. The data have implications for genotyping studies in brugian filariasis; they indicate that it may be important to concentrate on the younger age groups where individual environmental effects have not yet overruled the genetic influences on gain/loss of infection.(Received May 25 2003)
(Revised September 10 2003)
(Accepted September 10 2003)
Key Words: filariasis; IgG4; genetics; environmental factors; clustering of infection.
c1 Department of Parasitology, Leiden University Medical Center, Postbus 9600, 2300 RC Leiden, The Netherlands. Tel: +31 71 526 5067. Fax: 31 71 526 6907. E-mail: M.Yazdanbakhsh@lumc.nl