Bancroftian filariasis infection, disease, and specific antibody response patterns in a high and a low endemicity community in East Africa.

Abstract

Abstract. Bancroftian filariasis infection, disease and specific antibody response patterns in a high and a low endemicity community in East Africa were analyzed and compared to assess the relationship between these parameters and community transmission intensity. Overall prevalences of microfilaremia and circulating filarial antigenemia were 24.9% and 52.2% in the high and 2.7% and 16.5% in the low endemicity community, respectively. A positive history of acute attacks of adenolymphangitis was given by 12.2% and 7.1% of the populations, 4.0% and 0.9% of the adult (Ն 20 years old) individuals presented with limb lymphedema, and 25.3% and 5.3% of the adult males had hydrocele, in the high and the low endemicity community, respectively. Both infection and disease appeared earlier and reached much higher levels in the high than in the low endemicity community. The observed overall and age-specific infection and disease patterns in the two communities were in agreement with the view that these are primarily shaped by transmission intensity. No statistically significant relationships between infection status of fathers and mothers and that of their children were observed in any of the communities for either microfilaremia or for circulating filarial antigenemia. The overall levels (prevalence and geometric mean intensity) of filarial-specific IgG1, IgG2, IgG4, and IgE were significantly higher in the high endemicity community than in the low endemicity community. Surprisingly, the opposite pattern was found for IgG3. Community transmission intensity thus appears to be an important determinant of observed inter-community variation in infection, disease, and host response patterns in Bancroftian filariasis.

Evidence for Stopping Mass Drug Administration for Lymphatic Filariasis in Some, But Not All Local Government Areas of Plateau and Nasarawa States, Nigeria

“…Mathematical modeling has predicted that where LF prevalence at baseline is highest, longer and better MDA coverage is required, and may require the addition of vector control measures. 23 Our baseline mapping data did not indicate that these 10 LGAs were spatially clustered, but these LGA did have a fewer number of highly endemic baseline sites than the other 20 LGAs. Three baseline mapping villages (Magama in Langtang South, Kutu in Karu, and Binchi in Bassa; Figure 3) in the successful LGAs had 1999 antigen levels above 30% (the upper tercile of antigen prevalence among the 30 LGAs) 7 , whereas 15 out of the other 20 unsuccessful LGAs had one or more baseline sites with antigen levels above 30% (data not shown).…”

“…Similarly, the domain of 20 LGAs that failed the PacELF criterion would also fail the WHO TAS criterion in the 6-7 year olds.…”

“…It may be better to include adults when monitoring transmission because antigenemia is more prevalent among adults in endemic areas. 19,20 Reproductively viable (mf positive) infections have been found in adults in communities where no antigen-positive children could be identified. 21 However, using adults in stop MDA assessments has the disadvantage of potentially failing an area if CFA is caused by persistent antigen from non-viable worms.…”

“…Unfortunately, WHO guidelines for stopping onchocerciasis (ivermectin monotherapy) MDA in Africa are less well accepted than those for LF. 3 In terms of the 20 LGAs where antigen prevalence did not meet the PacELF criteria for stopping, continued MDA together with LLIN will likely act synergistically to hasten LF transmission interruption there. We plan to implement another survey following current TAS guidelines in 2012 in these LGAs, possibly at a combined EU level rather than LGA level, due to financial constraints.…”

Immunoepidemiology ofWuchereria bancroftiInfection: Parasite Transmission Intensity, Filaria-Specific Antibodies, and Host Immunity in Two East African Communities

“…We present here results from one such comparative immunoepidemiological analysis in which we focused on comparing observed age relationships between filarial specific antibody responses and W. bancrofti intensity in a community with low parasite transmission intensity in coastal East Africa with the relationships observed in a community in the same region with a higher transmission intensity (25,39,43). One feature of the analyses reported here was the use of a combined empirical data analysis and mathematical modeling approach for investigating mechanisms that may underlie the observed differences in the age patterns of parasite-specific antibody responses between communities exposed to different transmission pressures (24,25,50,51).…”