Mohamed A. Kenawy

Climate Change Influences on the Global Potential Distribution of the Mosquito Culex quinquefasciatus, Vector of West Nile Virus and Lymphatic Filariasis

Rapid emergence of most vector-borne diseases (VBDs) may be associated with range expansion of vector populations. Culex quinquefasciatus Say 1823 is a potential vector of West Nile virus, Saint Louis encephalitis virus, and lymphatic filariasis. We estimated the potential distribution of Cx. quinquefasciatus under both current and future climate conditions. The present potential distribution of Cx. quinquefasciatus showed high suitability across low-latitude parts of the world, reflecting the current distribution of the species. Suitable conditions were identified also in narrow zones of North Africa and Western Europe. Model transfers to future conditions showed a potential distribution similar to that under present-day conditions, although with higher suitability in southern Australia. Highest stability with changing climate was between 30°S and 30°N. The areas present high agreement among diverse climate models as regards distributional potential in the future, but differed in anticipating potential for distribution in North and Central Africa, southern Asia, central USA, and southeastern Europe. Highest disparity in model predictions across representative concentration pathways (RCPs) was in Saudi Arabia and Europe. The model predictions allow anticipation of changing distributional potential of the species in coming decades.

Ecology of the Mosquito Larvae in Urban Environments of Cairo Governorate , Egypt

Mosquitoes were surveyed over one year period in two localities in Cairo representing different levels of urban planning: El-Muqattam (planned) and Abu-Seir (unplanned). Culex pipiens, Cx. perexiguus, Cx. pusillus, Ochlerotatus caspius, Culiseta longiareolata and Anopheles multicolor were the collected species at both sites. Mosquitoes were more common in Abu-Seir than in El-Muqattam, with larvae of the filaria vector Cx. pipiens accounting for 81% and 52% of recorded individuals at these sites, respectively. Five types of the potential breeding habitats were detected of which, the cesspits (El-Muqattam) and drainage canals (Abu-Seir) were the most common while springs in El-Muqattam and drainage canals in Abu-Seir were the most productive types. Both Cx. pipiens and Cx. perexiguus bred year round with peaks of abundance coinciding with higher temperatures.

Surveillance of Arthropod-Borne Viruses and Their Vectors in the Mediterranean and Black Sea Regions Within the MediLabSecure Network

Purpose of ReviewArboviruses, viruses transmitted by arthropods such as mosquitoes, ticks, sandflies, and fleas are a significant threat to public health because of their epidemic and zoonotic potential. The geographical distribution of mosquito-borne diseases such as West Nile (WN), Rift Valley fever (RVF), Dengue, Chikungunya, and Zika has expanded over the last decades. Countries of the Mediterranean and Black Sea regions are not spared. Outbreaks of WN are repeatedly reported in the Mediterranean basin. Human cases of RVF were reported at the southern borders of the Maghreb region. For this reason, establishing the basis for the research to understand the potential for the future emergence of these and other arboviruses and their expansion into new geographic areas became a public health priority. In this context, the European network “MediLabSecure” gathering laboratories in 19 non-EU countries from the Mediterranean and Black Sea regions seeks to improve the surveillance (of animals, humans, and vectors) by reinforcing capacity building and harmonizing national surveillance systems to address this important human and veterinary health issue. The aim of this review is to give an exhaustive overview of arboviruses and their vectors in the region.Recent FindingsThe data presented underline the importance of surveillance in the implementation of more adapted control strategies to combat vector-borne diseases. Partner laboratories within the MediLabSecure network present a wide range of infrastructures and have benefited from different training programs.SummaryAlthough reporting of arboviral presence is not carried out in a systematic manner, the expansion of the area where arboviruses are present cannot be disputed. This reinforces the need for increasing surveillance capacity building in this region to prevent future emergences.

Ecology of cutaneous leishmaniasis in Sinai: linking parasites, vectors and hosts

Cutaneous leishmaniasis (CL) is a neglected clinical form of public health importance that is quite prevalent in the northern and eastern parts of Egypt. A comprehensive study over seven years (January 2005-December 2011) was conducted to track CL transmission with respect to both sandfly vectors and animal reservoirs. The study identified six sandfly species collected from different districts in North Sinai: Phlebotomus papatasi, Phlebotomus kazeruni, Phlebotomus sergenti, Phlebotomus alexandri, Sergentomyia antennata and Sergentomyia clydei. Leishmania (-)-like flagellates were identified in 15 P. papatasi individuals (0.5% of 3,008 dissected females). Rodent populations were sampled in the same districts where sandflies were collected and eight species were identified: Rattus norvegicus (n = 39), Rattus rattus frugivorous (n = 13), Rattus rattus alexandrinus (n = 4), Gerbillus pyramidum floweri (n = 38), Gerbillus andersoni (n = 28), Mus musculus (n = 5), Meriones sacramenti (n = 22) and Meriones crassus (n = 10). Thirty-two rodents were found to be positive for Leishmania infection (20.12% of 159 examined rodents). Only Leishmania major was isolated and identified in 100% of the parasite samples. The diversity of both the vector and rodent populations was examined using diversity indices and clustering approaches.

Population Ecology of Mosquitoes and the Status of Bancroftian Filariasis in El Dakahlia Governorate , the Nile Delta , Egypt

Mosquitoes were surveyed (Oct. 2010 & Apr. - Oct. 2011) in some localities representing 13 centers of El-Dakahlia Governorate. Six mosquito species were collected: Culex pipiens, Cx. antennatus, Cx. perexiguus, Ochlerotatus detritus, Anopheles pharoensis and An. tenebrosus. Culex pipiens was predominating (ca 79% larvae, 51% adults). Culex antennatus and Cx. perexiguus were also common. Of the Four types of the breeding habitats, the drainage canals were the most productive (53.4% larvae). For the three common species, the compiled larval density increases as water temp. increased and decreases as pH increased while adult indoor density increases as indoor and outdoor temp. and indoor RH increased and decreases as outdoor RH increased. Cx. pipiens significantly associated with Cx. antennatus (CAB=0.88 & I=0.48) while Cx. antennatus has a moderate association with Cx. perexiguus (CAB=0.47 & I=0.36). Out of 908 examined blood samples from ten centers, 7.49% were infected with Wuchereria bancrofti. The highest infection rates in some centers were associated with high indoor densities of Cx. pipiens females, the main filariasis vector. The situation necessitates a wide vector control program to minimize lymphatic filariasis transmission in this Governorate.

Rift Valley Fever in Egypt and other African countries: Historical review, recent outbreaks and possibility of disease occurrence in Egypt

This article reviews and discusses the historical and recent status of Rift Valley Fever (RVF) in Egypt and the other African countries based on the available and scattered reports. The recent outbreaks in African countries were reviewed and mapped out. Four major epidemics have been recorded in Egypt (1977, 1978, 1993 and 2003). The outbreak resulted in unpredicted human disease with severe clinical manifestations and heavy mortality as well as many abortions and deaths in sheep, goats, cattle, water buffalo and camels. Of the 18 culicine mosquito species that occur in Egypt, Culex pipiens and Cx. antennatus were implicated as vectors of RVF in Egypt based on their natural infection with RVF virus. Aedes caspius was also suspected of disseminating the virus among livestock based on host feeding and vector competence studies. The epidemiological factors related to the introduction and spread of RVF in Egypt are discussed. The study concluded that due to the availability and abundance of the potential vectors, suitability of environmental conditions, continuous importation of livestocks from Sudan, and the close association of susceptible domestic animals with humans, the RVF virus could possibly occur and circulate in Egypt.

Population genetics analysis of Phlebotomus papatasi sand flies from Egypt and Jordan based on mitochondrial cytochrome b haplotypes

BackgroundPhlebotomus papatasi sand flies are major vectors of Leishmania major and phlebovirus infection in North Africa and across the Middle East to the Indian subcontinent. Population genetics is a valuable tool in understanding the level of genetic variability present in vector populations, vector competence, and the development of novel control strategies. This study investigated the genetic differentiation between P. papatasi populations in Egypt and Jordan that inhabit distinct ecotopes and compared this structure to P. papatasi populations from a broader geographical range.MethodsA 461 base pair (bp) fragment from the mtDNA cytochrome b (cyt b) gene was PCR amplified and sequenced from 116 individual female sand flies from Aswan and North Sinai, Egypt, as well as Swaimeh and Malka, Jordan. Haplotypes were identified and used to generate a median-joining network, FST values and isolation-by-distance were also evaluated. Additional sand fly individuals from Afghanistan, Iran, Israel, Jordan, Libya, Tunisia and Turkey were included as well as previously published haplotypes to provide a geographically broad genetic variation analysis.ResultsThirteen haplotypes displaying nine variant sites were identified from P. papatasi collected in Egypt and Jordan. No private haplotypes were identified from samples in North Sinai, Egypt, two were observed in Aswan, Egypt, four from Swaimeh, Jordan and two in Malka, Jordan. The Jordan populations clustered separately from the Egypt populations and produced more private haplotypes than those from Egypt. Pairwise FST values fall in the range 0.024–0.648.ConclusionThe clustering patterns and pairwise FST values indicate a strong differentiation between Egyptian and Jordanian populations, although this population structure is not due to isolation-by-distance. Other factors, such as environmental influences and the genetic variability in the circulating Le. major parasites, could possibly contribute to this heterogeneity. The present study aligns with previous reports in that pockets of genetic differentiation exists between populations of this widely dispersed species but, overall, the species remains relatively homogeneous.

Entomological studies of phlebotomine sand flies (Diptera: Psychodidae) in relation to cutaneous leishmaniasis transmission in Al Rabta, North West of Libya.

Al Rabta in the North-West of Libya is a rural area where cutaneous leishmaniasis (CL) is endemic for long time. Few reports are available on sand flies in this area which is an important focus of CL. Therefore, this study aimed at updating the species composition, and monthly fluctuation of sand flies in this area. Sand flies were biweekly collected by CDC light traps from June to November 2012 and April to November 2013 in two villages, Al Rabta East (RE) and Al Rabta West (RW). Nine species (6 Phlebotomus and 3 Sergentomyia) were reported in the two villages. A total of 5605 and 5446 flies were collected of which Phlebotomus represented 59.30 and 56.63% in RE and RW, respectively. Sergentomyia minuta and Phlebotomus papatasi were the abundant species. Generally, more males were collected than females for all species. The overall ratios (males: females) for most of species were not deviated from the expected 1:1 ratio (Chi-squared, P>0.05). Sand fly abundance (fly/trap) is directly related to the temperature and RH (P<0. 01) while it inversely related to wind velocity (P>0.05). Flies were active from April to November with increased activity from June to October. Prominent peaks were in September and June. The abundance of P. papatasi and Phlebotomus sergenti, vectors of CL (August-October) coincided with the reported higher numbers of CL cases (August- November). The obtained results could be important for the successful planning and implementation of leishmaniasis control programs.

Characterization of the Mosquito Breeding Habitats in Two Urban Localities of Cairo Governorate, Egypt

The knowledge of the natural characteristics of the mosquito breeding habitats is important for implementing effective larval control program. For this, the association of six mosquito species ( Culex pipiens , Cx. perexiguus , Cx. pusillus , Ochlerotatus caspius , Anopheles multicolor and Culiseta longiareolata ) with the physical characteristics of their breeding habitats was examined in El-Muqattam and Abu-Seir; of the urban areas in Cairo Governorate. Based on the highest frequency of occurrence (P 10m perimeter), mud bottoms, presence of aquatic vegetations and absence of predators. The study concluded that the environmental control measures based on modifying habitat characteristics can be effective in controlling targeted mosquito species specially those vectors of diseases.

Development of polymorphic EST microsatellite markers for the sand fly, Phlebotomus papatasi (Diptera: Psychodidae)

BackgroundPhlebotomus papatasi is a widely distributed sand fly species in different tropical and sub-tropical regions including the Middle East and North Africa. It is considered an important vector that transmits Leishmania major parasites, the causative agents of cutaneous leishmaniasis. The development of microsatellite markers for this sand fly vector is of high interest to understand its population structure and to monitor its geographic dispersal.ResultsFourteen polymorphic microsatellite markers were developed with simple di-, tri- and tetra-nucleotide repeats. The F statistics calculated for the 14 markers revealed high genetic diversity; expected heterozygosity (He) ranged from 0.407 to 0.767, while observed heterozygosity (Ho) was lower and ranged from 0.083 to 0.514. The number of alleles sampled fall in the range of 9–29. Three out of 14 markers deviated from Hardy-Weinberg expectations, no significant linkage disequilibrium was detected and high values for inbreeding coefficient (FIS) were likely due to inbreeding.ConclusionsThe development of these functional microsatellites enable a high resolution of P. papatasi populations. It opens a path for researchers to perform multi locus-based population genetic structure analyses, and comparative mapping, a part of the efforts to uncover the population dynamics of this vector, which is an important global strategy for understanding the epidemiology and control of leishmaniasis.