Impact of polystyrene beads as a mosquito control measure to supplement lymphatic filariasis elimination activities in Socotra Island, Yemen

Lymphatic filariasis (LF) is targeted for worldwide elimination. In Yemen, all mainland implementation units met the WHO criteria for stopping mass drug administration (MDA) after 5 rounds. However, in Socotra Island these criteria were not met. Our study evaluated the efficacy of applying expanded polystyrene beads (EPBs) on the Culex population and the effect on LF transmission. Human and mosquito surveys were conducted in 40 randomly selected households in Hadibo (capital of Socotra) before and after application of EPBs. The EPBs intervention resulted in a reduction in mosquito density of 80% and a 64.3% reduction in microfilaria prevalence. The majority of interviewed households (98%) thought EPBs considerably reduced the mosquito population. After the intervention all collected pools tested negative. Application of EPBs is an effective supplement to MDA for achieving the goal of LF elimination.

A retrospective hospital study of human cystic echinococcosis in Egypt

Weperformed a retrospective study to determine annual clinical incidence of human cystic echinococcosis [CE] in 14 Egyptian hospitals between January 1997 and December 1999. From 492 353 records examined, 133 [0.027%] new human CE cases were recorded. Of these, 50 [37.6%] were from Alexandria and Matrouh hospitals, 33 [24.8%] from Giza Chest Hospital and 50 from other regions. Matrouh governorate had the highest annual clinical incidence [1.34-2.60 per 100 000] followed by Giza governorate [0.80-1.16 per 100 000]. About a third of those affected were aged

A retrospective hospital study of human cystic echinococcosis in Egypt

We performed a retrospective study to determine annual clinical incidence of human cystic echinococcosis (CE) in 14 Egyptian hospitals between January 1997 and December 1999. From 492 353 records examined, 133 (0.027%) new human CE cases were recorded. Of these, 50 (37.6%) were from Alexandria and Matrouh hospitals, 33 (24.8%) from Giza Chest Hospital and 50 from other regions. Matrouh governorate had the highest annual clinical incidence (1.34-2.60 per 100 000) followed by Giza governorate (0.80-1.16 per 100 000). About a third of those affected were aged < or = 20 years. Liver and lungs were the organs most affected. Although human CE is of low endemicity in Egypt, it may-represent a public health concern in Matrouh and Giza governorates.

Lymphatic filariasis in the Eastern Mediterranean Region: current status and prospects for elimination

Lymphatic filariasis [LF] represents a major public health problem in tropical and subtropical regions of the world. The disease is endemic or suspected in several countries of the Eastern Mediterranean Region. Recent advances in diagnosis and therapy led the World Health Assembly to pass a resolution in 1997 calling for “the elimination of lymphatic filariasis as a public health problem. ” The elimination strategy is based on rounds of mass drug administration of an annual single-dose of combined drug regimens for 5-6 consecutive years. Subsequent steps included formation of a Regional Programme Review Group to orient national LF control programmes towards the concept of elimination, provide advice, review each national plan of action and review annual reports. To date, Egypt and the Republic of Yemen have active national LF elimination programmes, however, elimination activities in the Republic of Yemen are still restricted to certain identified endemic regions. Other countries in the Region are on their way to verifying the situation and if LF is proved to be endemic, will start mapping endemic localities. This review sheds light on the status of LF elimination activities in the Region and highlights some of the major accomplishments.

Filariasis elimination in Egypt: impact of low micro-filaraemics as sources of infection for mosquitoes

The elimination strategy for lymphatic filariasis aims at reducing blood microfilaraemia to levels at which vector transmission cannot be sustained. We aimed to determine whether patients with pre-treatment low or ultra-low microfilaria [MF] counts could be a reservoir of infection after mass drug administration [MDA] with a combined regimen. Laboratory-reared mosquitoes were fed on 30 volunteers after 2 rounds of MDA. Microfilaria uptake, infectivity rates and number of Wuchereria bancrofti L3 per mosquito were assessed. One year after MDA-1, 6 subjects transmitted MF, but up to 9 months after MDA-2 transmission failed. Six months after MDA-2 > 90% had clear MF smears and either failed to transmit MF or transmitted MF that did not develop to L3. We conclude that the transmission cycle is seriously weakened after MDA-2

Filariasis elimination in Egypt: impact of low microfilaraemics as sources of infection for mosquitoes

The elimination strategy for lymphatic filariasis aims at reducing blood microfilaraemia to levels at which vector transmission cannot be sustained. We aimed to determine whether patients with pre-treatment low or ultra-low microfilaria (MF) counts could be a reservoir of infection after mass drug administration (MDA) with a combined regimen. Laboratory-reared mosquitoes were fed on 30 volunteers after 2 rounds of MDA. Microfilaria uptake, infectivity rates and number of Wuchereria bancrofti L3 per mosquito were assessed. One year after MDA-1, 6 subjects transmitted MF, but up to 9 months after MDA-2 transmission failed. Six months after MDA-2 > 90% had clear MF smears and either failed to transmit MF or transmitted MF that did not develop to L3. We conclude that the transmission cycle is seriously weakened after MDA-2.

Lymphatic filariasis in the Eastern Mediterranean Region: current status and prospects for elimination

Lymphatic filariasis (LF) represents a major public health problem in tropical and subtropical regions of the world. The disease is endemic or suspected in several countries of the Eastern Mediterranean Region. Recent advances in diagnosis and therapy led the World Health Assembly to pass a resolution in 1997 calling for "the elimination of lymphatic filariasis as a public health problem." The elimination strategy is based on rounds of mass drug administration of an annual single-dose of combined drug regimens for 5-6 consecutive years. Subsequent steps included formation of a Regional Programme Review Group to orient national LF control programmes towards the concept of elimination, provide advice, review each national plan of action and review annual reports. To date, Egypt and the Republic of Yemen have active national LF elimination programmes, however, elimination activities in the Republic of Yemen are still restricted to certain identified endemic regions. Other countries in the Region are on their way to verifying the situation and if LF is proved to be endemic, will start mapping endemic localities. This review sheds light on the status of LF elimination activities in the Region and highlights some of the major accomplishments.

A longitudinal study of schistosome intermediate host snail populations and their trematode infection in certain areas of Egypt

Seasonal variation of Biomphalaria alexandrina and Bulinus truncatus populations and their infection rates with schistosome and other trematode cercariae were studied longitudinally in four water courses located in Giza and Faiyoum Governorates. Abundance of both species varied from year to year and according to the type of habitat. The mean prevalence of Schistosoma mansoni in Biomphalaria was 0.29%, that of S. haematobium in Bulinus was 1.36%. Seasonal variations of age structure of the 2 vector snails were monitored throughout the survey period. Infection rates with schistosome and other trematodes among Bulinus and Biomphalaria increased with the increase in snail size. Data suggest the occurrence of an antagonistic interaction between schistosome and non-human cercariae, especially echinostome, in infected snails.

Field application of PCR-based assays for monitoring Wuchereria bancrofti infection in Africa

Approximately 50 million people in Egypt and sub-Saharan Africa have bancroftian filariasis and together they represent about a third of all cases of lymphatic filariasis (LF) world-wide. Currently, the Global Programme to Eliminate Lymphatic Filariasis, which was launched by the World Health Organization (WHO) in 1998, is largely based on repeated annual cycles of mass drug administration (MDA) to endemic populations. Also, some countries, including Egypt, are taking steps to improve LF vector-control interventions, to break the transmission cycle more effectively than is achievable with MDA alone. New tools and strategies for monitoring and evaluating elimination campaigns are needed. The last 20 years have witnessed dramatic advances in the diagnosis of LF for epidemiological purposes. The recent introduction and development of molecular technologies have moved parasite-detection systems from traditional methods (that are labour-intensive, tedious and often impractical) to improved PCR-based assays that have considerable potential for field use. The present article highlights the strengths and limitations of the PCR-based assays when used to detect filarial infections in mosquitoes (particularly for the xenomonitoring of elimination campaigns).

Development and standardization of a rapid, PCR-based method for the detection of Wuchereria bancrofti in mosquitoes, for xenomonitoring the human prevalence of bancroftian filariasis

PCR has recently been studied as a promising tool for monitoring the progress of efforts to eliminate lymphatic filariasis. PCR can be used to test concurrently at least 30 pools, with as many as 40 mosquitoes in each pool, for the presence of filarial larvae. The SspI PCR assay for the detection of Wuchereria bancrofti DNA in pools of mosquitoes has been used since 1994 in a variety of laboratories worldwide. During that time, the original assay has been modified in these different laboratories and no standardized assay currently exists. In an effort to standardize and improve the assay, a meeting was held on 15-16 November 2001, at Emory University in Atlanta, with representatives from most of the laboratories currently using the assay. The first round of testing was designed to test the four most promising methods for DNA extraction from pools of mosquitoes. Two of the four methods stood out as clearly the best and these will be now optimised and evaluated in two further rounds of testing.