Mass treatment to eliminate filariasis in Papua New Guinea.

BACKGROUND: The global initiative to eradicate bancroftian filariasis currently relies on mass treatment with four to six annual doses of antifilarial drugs. The goal is to reduce the reservoir of microfilariae in the blood to a level that is insufficient to maintain transmission by the mosquito vector. METHODS: In nearly 2500 residents of Papua New Guinea, we prospectively assessed the effects of four annual treatments with a single dose of diethylcarbamazine plus ivermectin or diethylcarbamazine alone on the incidence of microfilariae-positive infections, the severity of lymphatic disease, and the rate of transmission of Wuchereria bancrofti by mosquitoes. Random assignment to treatment regimens was carried out according to the village of residence, and villages were categorized as having moderate or high rates of transmission. RESULTS: The four annual treatments with either drug regimen were taken by 77 to 86 percent of the members of the population who were at least five years old; treatments were well tolerated. The proportion with microfilariae-positive infections decreased by 86 to 98 percent, with a greater reduction in areas with a moderate rate of transmission than in those with a high rate. The respective aggregate frequencies of hydrocele and leg lymphedema were 15 percent and 5 percent before the trial began, and 5 percent (P<0.001) and 4 percent (P=0.04) after five years. Hydrocele and leg lymphedema were eliminated in 87 percent and 69 percent, respectively, of those who had these conditions at the outset. The rate of transmission by mosquitoes decreased substantially, and new microfilariae-positive infections in children were almost completely prevented over the five-year study period. CONCLUSIONS: Annual mass treatment with drugs such as diethylcarbamazine can virtually eliminate the reservoir of microfilariae and greatly reduce the frequency of clinical lymphatic abnormalities due to bancroftian filariasis. Eradication may be possible in areas with moderate rates of transmission, but longer periods of treatment or additional control measures may be necessary in areas with high rates of transmission

Lymphatic filariasis in Oceania

Lymphatic filariasis caused by the mosquito-transmitted helminth parasite Wuchereria bancrofti is an important problem in Oceania. Of the 33 countries and territories included in this review, 24 have been found to be endemic for this disease at some time in the past, and 18 of these were classified as endemic at the start of the Global Programme to Eliminate Lymphatic Filariasis in 2000. After the implementation of large mass drug administration campaigns and (to a lesser extent) vector control over the last 15 years, only ten Oceania countries and territories were still considered to have ongoing transmission of lymphatic filariasis in 2015. Through a systematic literature search and review, we identified 79 individual studies of filariasis in Oceania that were published in 70 papers between 1995 and 2015. Data on mosquito (by species) and human infection prevalence using all currently available diagnostic tests, as well as estimates of acute and chronic filariasis morbidity, were extracted from these publications and tabulated in chronological order by country and outcome measure, noting sampling method and sample size in order to evaluate study quality and precision. No studies were identified from Micronesia; most studies in Melanesia and Polynesia were found from Papua New Guinea (PNG) (30) and French Polynesia (16), respectively. All other countries in Melanesia and Polynesia were represented by 1–7 studies except Wallis and Futuna. The systematic review identified 19 published studies of mosquito infections and 62 of human infections but only 3 on acute morbidity (all from PNG in the 1990s) and 11 on chronic morbidity. Since Oceania has a diverse set of mosquito vectors, published reviews of relative efficiencies of different mosquito genera were examined to shed light on their transmission dynamics and hence the potential for elimination of filariasis in Oceania. The review indicates the need for collation of unpublished reports and studies in addition to more geographically representative studies of remaining filariasis infection distribution, as well as quantification of the disability (acute attacks, lymphoedema, elephantiasis and hydrocoele) that will remain once transmission is interrupted, in order to plan for services to alleviate these lifelong effects

Neglected Tropical Diseases of Oceania: Review of Their Prevalence, Distribution, and Opportunities for Control

Among Oceania's population of 35 million people, the greatest number living in poverty currently live in Papua New Guinea (PNG), Fiji, Vanuatu, and the Solomon Islands. These impoverished populations are at high risk for selected NTDs, including Necator americanus hookworm infection, strongyloidiasis, lymphatic filariasis (LF), balantidiasis, yaws, trachoma, leprosy, and scabies, in addition to outbreaks of dengue and other arboviral infections including Japanese encephalitis virus infection. PNG stands out for having the largest number of cases and highest prevalence for most of these NTDs. However, Australia's Aboriginal population also suffers from a range of significant NTDs. Through the Pacific Programme to Eliminate Lymphatic Filariasis, enormous strides have been made in eliminating LF in Oceania through programs of mass drug administration (MDA), although LF remains widespread in PNG. There are opportunities to scale up MDA for PNG's major NTDs, which could be accomplished through an integrated package that combines albendazole, ivermectin, diethylcarbamazine, and azithromycin, in a program of national control. Australia's Aboriginal population may benefit from appropriately integrated MDA into primary health care systems. Several emerging viral NTDs remain important threats to the region