Investigation of risk factors for better control and surveillance of lymphatic filariasis in Papua New Guinea

• Main Author: Susapu, Melinda
• Format: Dissertation
• Language: English
• Published: University of Liverpool 2017
• DOI: 10.17638/03016510

Papua New Guinea (PNG) has an estimated population of 7 million inhabitants; of which 5.6 million are at risk of lymphatic filariasis (LF). LF is a debilitating disease caused by nocturnal periodic nematode Wuchereria bancrofti and transmitted by Anopheles mosquitoes, similar to malaria. LF is targeted for elimination, and PNG is a member of the Global Programme to Eliminate LF, which aims to interrupt transmission through mass drug administration (MDA) and providing patient care to those affected by the clinical conditions of lymphedema and hydrocoele. There is a need to collect and collate more national and published data to understand the risk factors influencing transmission so that control, elimination and surveillance can be targeted. This research project aimed to address some gaps in knowledge and conducted four specific activities including i) a scoping review of research on human prevalence and mosquito vectors in PNG and ii) a field survey to determine W. bancrofti antigenemia prevalence and related demographic and environmental risk factors iii) a micro-mapping microfilaria (Mf) survey and iv) entomological survey in an endemic area in Usino Bundi district of Madang Province. The review highlighted human prevalence as high as 48.8% and the significant impact of MDA in selected places. The entomological review found 17 studies on LF, with An. punctulatus, An farauti and An. koliensis identified as main vectors, and impacted by MDA and vector control for malaria, but most entomology was done in one region. The Ag prevalence survey conducted in 398 households across 4 villagesfound one village at significantly higher risk with 28.9% prevalence (Korona) with most clinical cases, while 2 villages had low prevalence (<5%) and one village none. Overall Ag prevalence significantly increased with individuals age and was higher in household made of semipermanent/bush material. Most (>90%) of participants did not know about LF or the LF Programme. The Mf survey of 301 individuals in high risk Korona village found 29.9% Mf prevalence which varied significantly by hamlet; Korona (24.6%; 16.6/µl), Koinduna (31.9%; 21.6/µl) and Tongona (43.3%; 17.3/µl). There was an increasing trend with age, and males (34.5%) had a significantly higher prevalence than females (23.4%), and those participants who reported using mosquito coils/spray for personal protection had a significantly lower prevalence (12.2%) than those who didn't (33.2%). Interpolated maps were able to show a relationship between Mf positives per household and selected risk factors. The entomology field survey found two main LF vectors, An. punctulatus (infection rate 14.6%) and An. farauti (8.5%), in all hamlets of the high risk village, Korona. The series of studies in this thesis provides key information to the National LF Elimination Programme to help target public health campaigns, and may be used to plan future research studies.