Historical overview of infantile visceral leishmaniasis in El Agamy, Alexandria, Egypt.

Infantile visceral leishmaniasis (IVL) is considered a rare and neglected disease in Egypt. An outbreak of the disease in El Agamy, Alexandria occurred in 1982 although the disease was previously reported 80 years before. Epidemiological and entomological studies were conducted ever since the 1982 outbreak to identify human cases, the parasite, reservoir host and the sand fly vector. Leishmania infantum MON-98, a new and unique zymodeme, was responsible of the disease. Stray dogs acted as the reservoir host and Phlebotomus langeroni was the proven vector. The parasite isolates from human cases were identical to the parasite isolates from the reservoir host and the sand fly vector. The El Agamy focus in 1982 was basically a rural Bedouin setting of recently built cement houses surrounded by lime stone fences. The numbers of human cases of IVL in this area have been declining, with the last reported case in 2005. This coincides with the completion of irregular urbanization of El Agamy which resulted in the disappearance of P. langeroni. In this review, we characterize the old focus of IVL in El Agamy based on published literature to identify factors underlying the appearance and disappearance of the disease.

Clinicoepidemiologic pattern of cutaneous leishmaniasis and molecular characterization of its causative agent in Hajjah governorate, northwest of Yemen.

The clinicoepidemiologic profile of 143 cases (93 males and 50 females) with cutaneous leishmaniasis from 18 villages of Hajjah governorate, Yemen was studied. Dry-type lesions were seen in 98.6% and wet-type lesions in 1.4% of patients. Lesions were localized in all cases with different morphological patterns. Microscopic examination of Giemsa-stained slit smears revealed amastigotes in 74.1% of patients with dry-type lesions and 0% in patients with wet-type lesions. The burden of the parasites in the lesions was high indicating active transmission of the disease. Most cases were from villages with moderate altitude range (8001-1600m). All age groups were affected, but most cases were seen in ages from 5 to 15 years. Leishmania species identification was done for all cases by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The biopsic material was scraped from both Giemsa-stained and methanol-fixed smears. The molecular characterization of Leishmania species revealed Leishmania tropica as the causative agent of cutaneous leishmaniasis in Hajjah, Yemen. The risk factors associated with the transmission of the disease and recommendations for improving case detection were discussed.

Current knowledge of sand fly fauna (Diptera: Psychodidae) of northwestern Yemen and how it relates to leishmaniasis transmission.

This report presents the results of the first entomological survey of the sand fly fauna in northwestern Yemen. Sand flies were collected using sticky paper traps and CDC light traps from Hajjah governorate, a cutaneous leishmaniasis focus due to Leishmania tropica. Six Phlebotomus species: P. alexandri, P. arabicus. P. bergeroti, P. orientalis, P. papatasi, P. sergenti and ten Sergentomyia species: S. africana, S. antennata, S. christophersi, S. dolichopa, S. dreyfussi, S. fallax, S. multidens, S. taizi, S. tiberiadis, S. yusafi were identified. P. alexandri was the most predominant Phlebotomus species and P. papatasi was a scarce species. S. fallax was the principal Sergentomyia species and S. dolichopa was the least species encountered. The diversity of the sand fly fauna within and among three altitudinal ranges using Simpson index and Jaccard's diversity coefficient respectively were measured. High species diversity was found in all altitude ranges. There seemed to be more association between sand fly fauna in higher altitudes with fauna from moderate altitudes. Sand fly seasonal activity showed a mono-modal trend in the lowland and a confluent bimodal trend in the highlands. Leishmania DNA could not be detected from 150 Phlebotomus females using PCR-RFLP. A possible zoonotic cutaneous transmission cycle due to Leishmania tropica in northwestern Yemen would involve P. arabicus as the sand fly vector and the rock hyrax as the reservoir host. The vector competence for P. alexandri as a vector of visceral leishmaniasis in Hajjah governorate is discussed.

Transmission of Leishmania infantum MON-98 to hamsters by the bite of Phlebotomus langeroni Nitzulescu (Diptera: Psychodidae).

The ability of Phlebotomus langeroni to successfully acquire and transmit Leishmania infantum MON-98 to hamsters was demonstrated. Sand flies and Leishmania both originated from an infantile visceral leishmaniasis focus in El Agamy Egypt. P. langeroni females were infected by feeding on lesions of needle-inoculated hamster and on infected blood suspension using a chick-skin membrane apparatus. Infection rate of sand flies fed on membrane was 88% compared to 7.8% for flies fed on leishmanial lesion. The transmission to hamster took place by the bites of infective flies taking a second blood meal, on the 8th to 10th day post-feeding. Furthermore, successful transmission was by the bites of flies that took no blood or that took full blood meal. Whereas flies that took full blood meal were not infective as indicated by dissection. In three hamsters, lesions developed after three months. Leishmania amastigotes were demonstrated from the lesion as well as from the liver and spleen of infected hamsters.

Impact of urbanization on the sand fly Phlebotomus langeroni nitzulescu in an old focus of visceral leishmaniasis in Egypt.

Changes in the environment often cause changes in disease transmission. Land use change especially urbanization can have a huge impact on transmission of vector-borne diseases. This study investigated the effect of urban development on the abundance of sand flies, in an old endemic focus of infantile visceral leishmaniasis in the north coast of Egypt. Sand fly abundance obtained in this study was compared to those obtained in 1984. In context remote sensing techniques are used to identify landscape features that might have influenced the spatial distribution of the sand fly vector in the area. In 2005, sand flies were completely absent from El Agamy. Sand fly habitat in El Agamy entirely changed and was replaced by urban settlements. Through the analysis of satellite imagery taken before and after, land use/land cover modification together with entomological data, the factors underlying the bionomics of sand flies are discussed.

Climatic factors influencing the abundance of Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) in the Nile Delta.

Ecological studies on sand flies were carried out in two villages of the Nile Delta Governorates namely; Kafr Tahla (Qalyubiya) and el Quantara el Beida (Kafr el-Sheikh) from September 2003 to August 2005. Sand flies were collected weekly from around houses, stables and near rodent burrows using sticky paper traps. A total of 9529 sand flies were collected from the two villages, all of which were identified as Phlebotomus papatasi. Sand fly activity started from April to December with a bimodal annual pattern. The sex ratio of collected sand flies was significantly male biased. Data analyses revealed that sand fly densities were strongly correlated to temperature but not to relative humidity or wind velocity. Variation in the densities of P. papatasi in both villages did not show a significant effect due to lunar phases. However, sand fly activity was highly positively correlated to fraction illumination.

Attachment of Leishmania major and Leishmania infantum in the midgut of their respective sand fly vectors Phlebotomus papatasi and Phlebotomus langeroni (Diptera: Psychodidae).

The attachment of Leishmania infantum and Leishmania major in the midgut of experimentally infected Phlebotomus langeroni and Phlebotomus papatasi was examined by transmission electron microscopy. Cellular damage in the midgut of infected flies as a byproduct of infection was observed in both species. A difference in the mode of attachment of flagella to the midgut of their respective sand fly vectors suggested higher adaptation between L. major/P. papatasi compared to L. infantum/P. langeroni.

Spectral and landscape characterization of filarious and non-filarious villages in Egypt.

Filarial disease is endemic in Egypt in some villages of Nile Delta governorates where it is transmitted by Culex pipiens female. GIS functions are used to identify environmental indicators of high-risk village as indicated by mosquito density, human infection rate, vector species composition, mean life expectancy "e(o)" & environmental variables (geology, hydrology, soil types, etc) as well as meteorological factors (temperature, RH and rainfall) in relation to filaria transmission risk. Remote-sensing technology was used to distinguish between the two studied villages as high and non-infected, as defined by microfilarial prevalence. The results indicate that filaria transmission risk is higher at an area characterized by highly productive aquifers, silt clay soil, receiving little amount of rain with low relative humidity (RH). The results indicate that the most important landscape elements associated with prevalence are water and different vegetation. This work showed that the integration between GIS and remote sensing technologies to analyze and identify the environmental factors, associated with the disease, did not only allow mapping icurrent spatial patterns, but also predicting its distribution under expected future developmental and environmental changes.

Studies on rodents role as reservoir hosts of leishmaniasis with specical reference to their ectoparasites in Suez Governorate.

The distribution of rodents was studied in three different habitats. Seven rodent species were identified: Rattus norvegicus, R. alexandrinus, R. frugivorous, Mus musculus, Acomys russatus, Meriones sacramenti and Gerbillus pyramidum. The species distribution varied with the habitat type. The highest density of rodents was in July and August and the lowest one was in January. However, some species were collected all the year round. The rodents were investigated for the endo- and ecto-parasites. No Leishmania parasites were found. The ectoparasites were: Xenopsylla cheopis, Leptopsylla segnis and Ctenocephalides felis, Polyplax spinulos, Hyalomma dromedarii (nymph) and Echinolaelaps echidninus and Hemolaelaps glassgowi. Ecto-parasites were on rodents all year-round in domestic habitat and peridomestic habitats. In wild one, ecto-parasites activity was from March to December. The rodents' role as reservoir for L. major was experimentally studied. Rodents inoculated with L. major together with hamster and BALB-c mice developed cutaneous lesions. The active lesions, the rodents' ecological habitats and the presence of insect-vector may pave the way to an epidemic zoonotic leishmaniasis role.

Ecology, biology and susceptibility of Phlebotomus papatasi to Leishmania experimental infection in Suez Governorate.

Zoonotic cutaneous leishmaniasis (ZCL) is endemic in Sinai Peninsula. The sand fly and reservoirs were investigated in Suez G., since new settlements and land reclamation programs are ongoing. The results showed that Phlebotomus papatasi reached its highest density in September. The successfully colonized P. papatasi facilitated its biology and competence study. An autogenous trait was proven within P. papatasi population indicating its ability to survive and breed during adverse conditions. The vector competence was carried out under laboratory condition through feeding on lesion of a L. major experimentally infected hamster and by membrane feeding technique. Both hamsters and BALB-c mice inoculated with L. major developed ZCL lesions.

Human zoonotic cutaneous leishmaniasis and associated sand flies (Diptera: Psychodidae) in Sheikh Atiya village, southern Sinai, Egypt.

Zoonotic cutaneous leishmaniasis is endemic in Sinai Peninsula. Human cases were recorded from the northern Sinai, however little was known about the disease in southern Sinai. During entomological surveys conducted southern Sinai in summers of 1997-1999, a clinically confirmed ZCL case was encountered for the first time in Sheikh Atiya village in June 1999. The parasite was isolated and identified as L. major using cellulose acetate electrophoresis. A total of 784 phlebotomine sand flies were collected. Sand fly species composition at Sheikh Atiya village showed that P. papatasi and P. alexandri were the most abundant species in the area and each comprises about 47 % of the flies collected. P. sergenti and P. kazeruni occurred in very low numbers. All the female flies dissected (N = 304) were negative for any Leishmania-like flagellates. When the identified isolate was inoculated in the footpads of a clean laboratory colonized Acomys cahirinus dimidiatus, a lesion was developed on the site of inoculation 9 months post injection. The role of P. alexandri and A. c. dimidiatus in transmission of leishmaniasis in southern Sinai remains questionable. Environmental factors contributed to the appearance of ZCL in the area are discussed.