Value of Haemonchus longistipes purified antigens in diagnosis of gastro-intestinal nematodes infection in camels.

Fractionated Haemonchus longistipes crude antigen revealed 7 protein fractions at molecular weights of 93, 74, 67, 56, 32, 26 and 16 kDa. The bands at 56, 32 and 26 kDa reacted specifically with H. longistipes hyperimmune sera prepared in rabbit (1:100 dilution) using EITB technique. The eluted concentrated fractions as well as crude worm antigens were used in diagnosis of natural infection of Gastro-Intestinal Nematodes (GIN) only or associated with other parasites in camels using ELISA technique. H. longistipes crude antigen and fraction of 26 kDa induced high sensitivity in diagnosis of infection in animals harboring GIN only (sensitivity was 95-100%), while it was 85.0-93.3% with 32 kDa fraction and 55.5-73.3% with that of 56 kDa using ELISA technique. The two H. longistipes eluted protein fractions of 26 and 32 kDa showed higher sensitivity than their crude antigens in diagnosis of GIN infection mixed with other parasites. While, Protein bands of 26 kDa appeared more sensitive than the other protein bands in detection of anti- H. longistipes antibodies at higher serum dilution. With special superiority for fraction of 26 kDa, in comparison with the other antigens, sharp specificity or sensitivity in diagnosis, could not be achieved in this study especially in case of mixed infection with other parasites, where these animals might be immune-compromised.

Geographic information systems as a tool for control program management for schistosomiasis in Egypt.

During a 4-year study a geographic information system (GIS) risk model was constructed for predicting the relative risk of schistosomiasis in Kafr El-Sheikh governorate, Egypt. A 1-year 1990-1991 time series on diurnal temperature difference (dT) prepared from the advanced very high resolution radiometer (AVHRR) sensor on the NOAA-11 satellite was used to develop a regional risk model for the Nile delta based on thermal-hydrological domains. A May 15, 1990 Landsat TM scene (path 177, Row 38) was used to develop a local 'village-scale' environmental risk model based on higher resolution satellite sensor data (30 m picture element size at earth surface). Four of ten classes derived from a tasseled cap (Tcap) transformation of the Landsat TM scene were shown to be significantly related to a 5-year Schistosoma mansoni prevalence database from the Ministry of Health. A risk model was developed based on dT and the proportional area of the four Tcap classes in 5 km(2) buffer zones centered on rural health unit (RHU) reporting units. Available historical data on S. mansoni and its snail host Biomphalaria alexandrina, as well as recent field collected data were gathered and incorporated as separate themes. Model validation was done using data collected on snail population bionomics-infection rates, water quality, underground water table and cercariometry at 13 hydrologically representative sites. The role of soil type, water table and water quality was studied at 79 of 154 rural health unit sites. The model permitted retrieval of relevant data by RHU point location. For the first time in Egypt, the Kafr El-Sheikh GIS schistosoma prediction model can support MOH efforts to make more accurate control program decisions based on environmental predilection sites of endemic Schistosomiasis mansoni.

Development and validation of a satellites based geographic information system (GIS) model for epidemiology of Schistosoma risk assessment on snail level in Kafr El-Sheikh Governorate.

The aim of the present study was to test the accuracy of Advanced Very High Resolution Radiometer (AVHRR) satellite derived temperature difference (dT) maps as a guide for the suitability of the environment for local snail hosts and Schistosoma development-transmission at the village level. The study provided field validation data from 13 villages in Kafr El Sheikh in the Nile Delta that sites present in wet zones of low dT value have more abundant snail populations than that present in the drier zones with high dT values. Results suggest that lower dT values were associated with wetter hydrologic regimes related to the level of underground water table and that this is reflected in the abundance of snail populations and Schistosoma snail infection rates at the village level. Water quality parameters on pH salinity and dissolved oxygen were not correlated with presence of Schistosoma infected snails. Results indicate that abundance of snails and S. mansoni prevalence are related to thermal-hydrology domains associated with surface water, that habitat suitability is related to depth to water table and that regional hydrology characteristics that affect snail host habitat suitability (ie. wet, moist, dry or very dry) can be evaluated using AVHRR dT maps.