Combining different diagnostic studies of lymphatic filariasis for risk mapping in Papua New Guinea: a predictive model from microfilaraemia and antigenaemia prevalence surveys

Alvaro Berg Soto,Nelly Sanuku,Melinda Susapu,Daniel Tisch,Patricia M Graves,Peter Wood,Zhijing Xu,Christopher L King,Leanne J Robinson

doi:10.1186/s41182-018-0123-8

Abstract

BackgroundThe Global Programme to Eliminate Lymphatic Filariasis has encouraged countries to follow a set of guidelines to help them assess the need for mass drug administration and evaluate its progress. Papua New Guinea (PNG) is one of the highest priority countries in the Western Pacific for lymphatic filariasis and the site of extensive research on lymphatic filariasis and surveys of its prevalence. However, different diagnostic tests have been used and thresholds for each test are unclear.MethodsWe reviewed the prevalence of lymphatic filariasis reported in 295 surveys conducted in PNG between 1990 and 2014, of which 65 used more than one test. Results from different diagnostics were standardised using a set of criteria that included a model to predict antigen prevalence from microfilariae prevalence. We mapped the point location of each of these surveys and categorised their standardised prevalence estimates.ResultsSeveral predictive models were produced and investigated, including the effect of any mass drug administration and number of rounds prior to the surveys. One model was chosen based on goodness of fit parameters and used to predict antigen prevalence for surveys that tested only for microfilariae. Standardised prevalence values show that 72% of all surveys reported a prevalence above 0.05. High prevalence was situated on the coastal north, south and island regions, while the central highland area of Papua New Guinea shows low levels of prevalence.ConclusionsOur study is the first to provide an explicit predictive relationship between the prevalence values based on empirical results from antigen and microfilaria tests, taking into account the occurrence of mass drug administration. This is a crucial step to combine studies to develop risk maps of lymphatic filariasis for programme planning and evaluation, as shown in the case of Papua New Guinea.

Highlights

The Global Programme to Eliminate Lymphatic Filariasis has encouraged countries to follow a set of guidelines to help them assess the need for mass drug administration and evaluate its progress
About 68 million individuals in the world remain affected [7], with the corresponding DALYs estimated at 2.02 million [8]. This estimation does not include disability from cases of mental illness resulting from stigmatising conditions, which was estimated at 5.09 million DALYs based on 2010 GBD data [5]. These numbers are of concern, suggesting that the Global Programme to Eliminate Lymphatic Filariasis (GPELF) must continue its strategy of annual single-dose mass drug administration (MDA) programs [1] to reduce the burden of lymphatic filariasis in the world
We examined the attributes of our proposed model and its practical use to improve the accuracy of Lymphatic filariasis (LF) risk maps in Papua New Guinea (PNG)

Summary

Introduction

The Global Programme to Eliminate Lymphatic Filariasis has encouraged countries to follow a set of guidelines to help them assess the need for mass drug administration and evaluate its progress. Lymphatic filariasis (LF) is a mosquito-transmitted disease caused by a parasitic nematode (predominantly Wuchereria bancrofti) that can seriously damage lymphatic vessels [1] This frequently leads to cases of acute and chronic lymphoedema (extreme inflammation of lower limbs) and hydrocoele (swollen scrotum in men), potentially resulting in life-long chronic morbidity [2,3,4]. Since the resolution to implement the Global Programme to Eliminate Lymphatic Filariasis (GPELF) by the World Health Assembly [6], the estimated global burden of LF has significantly decreased by 59% between 2000 and 2013 [7] Despite this amazing achievement, about 68 million individuals in the world remain affected [7], with the corresponding DALYs (disability-adjusted life years lost) estimated at 2.02 million [8]. These numbers are of concern, suggesting that the GPELF must continue its strategy of annual single-dose mass drug administration (MDA) programs [1] to reduce the burden of lymphatic filariasis in the world

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