Independent assessment of Mass Drug Administration in filariasis affected Surat city.

The Mass Drug Administration (MDA) done in Surat city (Gujarat) during 2005, revealed good impact on infection and infectivity in mosquitoes and also on microfilaria rate & mean infection density. The overall impact seen was 23% on mf rate, 28% on mean mf density, 65% on infection rate and 50% on infectivity rate in vectors. Indigenous population contribution to microfilaria cases was 9.7%, whereas migratory population contributed 72.2%; predominant 51.9% from Orissa and 20.3% from U.P. Of the total 3640 persons interviewed for MDA compliance in seven zones of the Surat city revealed that actual drug consumption was 76.7% (2792/3640). Another 11.9% although took the drug but did not consume and 11.4% refused. Important reasons for consuming was fear to get the disease (40.7%) and for not consuming; 'will consume after meal' (6.9%), too many tablets (1.7%), seek consent from doctor (1.5%), lack of awareness (1.4%) etc. Refusal was mainly due to the reason as respondents felt apparently healthy. Assessment of IEC activities suggested that main awareness was created by media (local or national TV, banners or handbills, local news papers or mike announcement) alongwith some impact made through NGO's. These observations clearly indicated the utility of effective health education for optimum community participation and shown that it was crucial for successful community based elimination campaign. However some gray areas also suggest the scope for further improvements.

Indicator dilution measurements of flow parameters in curved tubes and branching networks.

An experimental investigation has been made of the application of the indicator-dilution bolus-injection technique to measure flow rate, mean transit time and vessel volume with steady flow in curved tubes and branching networks. Measurements were made with 131I in 2N KCl and 131I-human serum albumin in isotonic saline, plasma and whole blood under laminar flow conditions up to a Reynolds' number of 460. The flow rate estimations are more reliable than those obtained for flow through straight tubes, due to secondary flows tending to disperse the indicator uniformly over the vessel cross-section. Even so, estimations of mean transit time and vessel volumes, using accepted theoretical formulae, may be as much as 200% in error. Similar measurements have been made of the flow parameters with bifurcations and branching networks. The indicator is not partitioned between the branches in proportion to the flow rate, as is assumed in the original indicator dilution theory, except when there is complete symmetry of the flow. An alternative method of estimating the vessel volume was used and shown to give an accurate estimate of the true volume in these circumstances.

The variation of indicator dilution curves with velocity profile.

A theoretical analysis has been made of the effect of different velocity profiles on the dispersion of a non-diffusable solute in fluid flow down a straight tube. An experimental investigation of this type of dispersion was made by monitoring the transport of radioactively labelled red blood cells in whole blood at flow rates within the non-Newtonian viscosity range. The dispersion curves obtained are consistent with a progressive flattening of the velocity profile as the flow rate is reduced, though a more rapid clearance than that predicted theoretically occurs in the tail region of the curves. The accepted indicator dilution techniques of estimating the flow rate and vessel volumes are considerably in error. An alternative method of accurately estimating the vessel volume is suggested.