Rapid assessment procedures (RAP) for lymphatic filariasis.

BACKGROUND

New strategies are emerging for control of filariasis in terms of chemotherapy and vector control. Field application of these tools requires mapping and prioritization of filaria-endemic areas and quantification of the infection/ disease burden. Available procedures are time-consuming, costly and have poor sensitivity. Therefore, rapid assessment procedures need to be developed to assess the disease burden as well as monitor and evaluate control programmes.

METHODS

Data collected on different variables from 25 areas in India and elsewhere were used. The relationship between prevalence of human infection and vector infection rate was analysed quantitatively. Due to lack of independent samples, only qualitative analysis was carried out between other epidemiological variables such as infection and disease prevalence in relation to age, gender and manifestation.

RESULTS

There was a significant positive correlation between vector infection rate and infection prevalence in humans, suggesting that vector infection can be used as an indicator in the rapid assessment of infection prevalence. Scatter plots showed that community screening may be limited to the age group of 11-30 years for infection prevalence and 20-50 years for disease prevalence. Further, clinical surveys may be limited to only hydrocele prevalence which may be sufficient to predict the total disease. This can also be used as an alternative method by the community itself for delimiting endemic areas.

CONCLUSIONS

Vector infection rate may be used as an indicator for rapid assessment of human infection. Alternatively, blood smear examination could be limited to the age group of 11-30 years. For a rapid survey of the diseases, males in the age group of 20-50 years could be examined only for hydrocele.