The ecological characteristics of Anopheles mosquitoes associated with low malaria transmission in Siwa oasis, Egypt.

The ecology of Anopheles sergentii and An. multicolor was investigated over eight months to examine the entomological factors maintaining the low Plasmodium vivax transmission in Siwa oasis. The two species were encountered as larvae while the dominant species, Anopheles sergentii was also collected as adults. Breeding sites were characterized for the two species in six localities. Larvae of both species were common during June and November. In Bahi El Din as an indicator village with a higher endemicity, An. sergentii females were endophilic but more common inside animal sheds than in houses, attracted more to donkey-baited traps than to human hosts, more endophagic as human biters and were more common in May/June and November. Female survivorship was higher in November than in the other months. Vector potential of An. sergentii was predicted and revealed that the species characteristics (low human contact, short survival and zoophilic feeding behavior) are responsible for maintaining such low and unstable malaria in Siwa oasis.

Distribution and ecology of the mosquito fauna in the southwestern Saudi Arabia.

A mosquito Larval survey was carried out in the Southwestern region of Saudi Arabia for a two subsequent years period. Nine mosquito species were identified; 4 Anopheline species; Anopheles arabiensis, An. sergentii, An. multicolor and An. tenebrosus and 3 Culicine species, Culex pipiens, Cx. quinquefaciatus and Cx. theileri as well as one Aedine species, Aedes caspius and Culiseta subochrea. A map was made showing the distribution of the encountered species and a full description of all breeding places was made also. The association of different species in each breeding site was also recorded.

Comparison of the life table characteristics of Anopheles sergentii (Diptera: Culicidae) from two malarious areas in Egypt.

Life table characteristics were examined for the malaria vector, An. serenti from two Faiyum villages: Tersa (T) and El Nazlah (N) from Siwa oasis (Sw) under constant laboratory conditions at 25 degrees C and 70% RH. Females of T, N and Sw completed 4, 5, and 2 gonotrophic cycles (gc) respectively. The first gc required a significantly longer period (p<0.05) than the subsequent ones. Development times for Sw immatures were longer (p<0.05) than for the other colonies. Life expectancies at emergence for males of the 3 colonies were significantly shorter than for their respective females. Generation time was shorter (p<0.05) for T (mean = 31.15 days) than for Sw (37.81 days) or N (43.64 days) colonies. The birth rate of Sw colony (mean = 0.33 female female/female) was significantly higher (p

Isolation, purification and ultrastructure of bacteriophages from natural mosquito breeding places in Egypt.

Two bacteriophages were isolated from field collected samples representing two different mosquito breeding places. The phage AB-1 (isolated from Abheit village, Faiyoum Governorate "seepage water") and the phage GA-2 (isolated from El-Gabal El-Asfer Qualyobia Governorate "sewage drain water") were purified. Both bacteriophages were ultrastructurally described with respect to their morphology, dimensions, phases of bacterial attack and lysogeny. No major differences were observed between both isolated phages in relation to specificity, however; they were isolated from two different types of breeding places and two different geographic areas as well. This study may assume a wide host range of the isolated phages and reflect how bacterial insecticides used for mosquito larval control could be inhibited by such bacteriophage.

Comparative inhibitory action of 4 standard bacteriophages on the larvicidal activity of certain mosquito pathogenic bacteria against Culex pipiens larvae.

Four bacteriophage (CP-51, CP-54, Yousten-4 and Yousten-14) were assayed against 7 entemopathogenic bacterial strains. The two CP ones, indicating variability of the host range of the tested phages which was suggested to be related to the environmental characteristics of the tested strains. On testing the susceptibility of 5 bacterial strains to the phage Yousten-4 at different cultural ages, a correlation was found between incubation time and level of bacterial susceptibility to the tested phage. This observation was explained to be due to the number of vegetative cells and/or sporulation.

A field survey of bacteriophage contamination of mosquito breeding places, inhibiting bacterial insecticide.

Twelve geographically different mosquito breeding places were described and sampled for the detection of naturally existed bacteriophage viruses which could transduct and lysate 5 entomopathogenic bacteria. The surveyed places are classified into seepage, sewage, and irrigation breeding water. Bacterial free filtrates of the collected samples were assayed against the tested bacteria in vitro and against 3rd instar Culex pipiens larvae as well. Nine out of the twelve places could demonstrate the presence of phages. Bacillus thuringiensis H-14 was foud susceptible to phage(s) present in polluted and irrigated water of 5 location, while, B. thuringiensis Berliner was susceptible to only a specific phage of one breeding place (polluted, sewage water). With regard to Bacillus sphaericus strains 1593 and 114, bacteriophages of sewage and irrigated water could lysate them and these phages are characterized by being of a moderate host range, except one phage which showed high specificity with strain 114 and was detected in a polluted sewage water sample collected from Dakahliya Governorate. The detected phages proved to lysate both B. thuringiensis H-14 and B. sphaericus 1593 on their larvicidal action through a series of bioassay experiment, almost all results indicate the presence of a significant inhibitory activity.

Distribution and host-relationship of ticks (Ixodoidea) infesting domestic animals and rodents in Sinai Peninsula.

Geographical distribution of ticks infesting farm animals in Sinai Peninsula revealed the presence of 12 tick species namely Hyalomma dromedarii, H. impeltatum, H. an anatolicum, H. an. excavatum, H. marginatum rufipes, H. m. turanicum, H. schulzei, Rhipicephalus sanguineus, R. turanicus, Boophilus annulatus, Ornithodors erraticus and Argas persicus. The distribution map of those species is given. The areas of Sinai could be arranged as regards the number of tick species in the following descending order, Beer Lehfin & St. Cathrine (9 spp.), Kosaimah & Nuweibah (8 spp.), Arish & Godirate (7 spp.), Firan (6 spp.) Beer El-Abd, Zowaid, Rafah, Quntara, Wadi Hadra & El Tur (5 spp.), Abu Redis, and Hammam Pharon (4 spp.).

Leishmania infection sought in rodents in north Sinai, Egypt.

Zoonotic cutaneous leishmaniasis (ZCL) is endemic in certain foci in North Sinai. In the present study, eight species of commensal and wild rodents were trapped from seven areas. Suggestive ZCL lesions were seen on R. rattus, R. norvegicus, G. pyramidum, G. ander soni, G. gerbillus and Meriones sacramenti. Positive Giemsa stained smears were identified in G. pyramidum. The results were discussed. It was concluded that the ZCL transmission cycle, animal reservoirs, sand fly vector and man, is documented.

Spotted fever rickettsiae in ticks from the northern Sinai Governate, Egypt.

A field study was initiated in 1988 to investigate whether spotted fever group rickettsiae occur in geographic areas in Egypt that are adjacent to an area in the southern Israeli Negev that has a defined focus of spotted fever disease. Ticks were collected from dogs, sheep, and camels at four study sites in the northern Sinai. Tick hemolymph was processed for rickettsial detection by staining with fluorescein isothiocyanate-conjugated antibody to Rickettsia rickettsii. Of the 442 hemolymphs examined, 15 contained immunofluorescent rickettsiae. Eight hemolymph test-positive (HT+) ticks were Rhipicephalus sanguineus removed from dogs; the other HT+ ticks comprised three Hyalomma species, H. anatolicum, H. impeltatum, and H. dromedarii. Both HT+ and HT- ticks were tested for rickettsial DNA using the polymerase chain reaction (PCR). Eight of 10 HT+ field-collected ticks were PCR positive (PCR+). All laboratory colony R. rickettsii-infected ticks were PCR+. No HT- ticks from field or laboratory isolates were PCR+.

Experimental efficiency of Phlebotomus papatasi in maintaining development of four species of Leishmania.

Experimental infections were carried out to evaluate the capability of 3 species of Phlebotomus to acquire and allow development of 4 species of Leishmania. The sand-flies were allowed to feed on infective blood by a membrane feeding technique and infected vertebrate hosts. The species of Phlebotomus experimented with were P. papatasi (Egyptian and Indian strains), P. dubosqi (Sinegal strain), and P. perniciosus (French strain). The species of Leishmania used were L. tropica (Afganistanian strain) in blood and L. major (Egyptian strain) in blood, in volunteer patient and in hamster, L. major (Morocco strain) in Meriones shawi, L. infantum (French strain) in dog and L. enrietti (Brazilian strain) in Guinea-pig. The results showed that Egyptian P. papatasi was the most suitable species for Egyptian L. major in blood followed by P. dubosqui. On the other hand, P. dubosqui was the most suitable species for L. tropica in blood followed by Indian P. papatasi. On the other hand, Egyptian P. papatasi acquired L. major from hamster (38.2%) and L. enrietti from Guinea pig (1.9%), but not L. major from the patient. Indian P. papatasi acquired L. major from Meriones (5.6%), L. infantum from dog (1.09%) but not L. enrietti from Guinea pig. Generally speaking, L. major was more engalfed by P. papatasi (2 strains) from the artificial source (blood) than from the vertebrate hosts.

Bacterial contamination of the housefly Musca domestica, collected from 4 hospitals at Cairo.

Four general hospitals were surveyed for bacterial contamination of the house fly, M. domestica which were caught inside the hospital sites and outside surroundings, especially, general garbages. Fly collections were made using the hanging sticky ribbon traps (spiralette). Bacterial isolation was made from each sample both externally and internally during two successive years representing the different seasons of the year. Twenty one bacterial isolates were identified from the 4 surveyed hospitals belonging to six families; Enterobacteriaceae (9 species each), Brucellaceae (2 species), Acromobacteriaceae and Pseudomonodaceae (one species each).

Two successive years studies on Phlebotomus papatasi in North Sinai Governorate, Egypt.

No doubt, zoonotic cutaneous leishmaniasis (ZCL) is increasing in North Sinai Governorate. The causative agent, L. major was identified as well as two animal reservoir hosts, Gerbillus pyramidum and Meriones crassus. This paper was intended to study the seasonal abundance and the sex ratio of the suspected insect, Phlebotomus papatasi as well as to search for natural infected in wild caught females. The C.D.C. miniature light traps were used for adult collections, dissection was used for demonstration of the promastigotes and biochemical typing was used for identification of isolated strain. The results showed that (a) the seasonal activities started in April and ended by the end of November, with a well marked bimodal distribution in one year, (b) the sex ratio (male to female) 1:2.9 (c) 0.14% of 4208 females were naturally infected with promastigotes and typing proved to be Leishmania major, zymodeme LON 70.

House-fly distribution in certain general hospital in Cairo.

Fly sampling was evaluated under laboratory conditions before starting the field surveys. Three different fly traps were tested, of which the Spiralettes (a commercial one) proved to be the most efficient. Sampling conditions were also considered in this laboratory evaluation, light, air current, swinging, height and temperature were tested, all of them have affected fly trapping except height. Fly density and distribution in two general hospitals and two specialized ones, were estimated in order to evaluate them epidemiologically in relation to hospital bacterial contamination. Results of these surveys revealed the followings: (1) The location of the hospital has no impact on the fly density. (2) Flies are attracted more to swinging hanged ribbon traps than to fixed ones. (3) Fly densities were relatively high in the main kitchens and the main garbages followed by toilets (common ones), patient wards, outpatients investigating rooms, surgical theaters and plasterrooms of the hospitals. (4) Fly density is higher during warm seasons than in cold ones.

The role of rodents as reservoirs for some diseases in new reclaimed areas in north Sinai.

In a trial to determine the role of Sinai rodents as reservoirs to rickettsial diseases, the IFA technique was used to detect the presence of R. typhi and spotted fever group in blood of some commensal and wild rodent species collected in Sinai during the last five years (1985-1989). Out of 277 Rattus spp. collected in El Arish (47.3%) were positive to R. typhi and only (5.9%) of 35 Mus musculus were positive to R. typhi. As for Gerbillus spp. only (1.5%) of 206 animals were positive for R. typhi. The positive cases of spotted fever group were (34.6%) in Rattus spp. and (18.8%) in Gerbillus spp.

Bacterial contamination of water wells in Wadi el-Sheikh area, in southern Sinai.

A bacterial assessment of water supplies must be done in Egypt as in order to improve the quality of useable water. Saint Katherine, Southern Sinai, was selected as being a populated area where wells are the only source of water for the local population. During one year, water of seven wells in Wadi El-Shiekh were bactiologically studied (El-Arbaien, Haron, Eid, Zitona, Farhan, Sahab and Gofa). The pouring plate technique was used to estimate the total viable bacterial count (TVB). The most probable number (MPN) technique was used to estimate total coliform (TC) and fecal coliform (FC) bacterial count. A result indicates that Al-Arabaien well has the least count of TVB throughout the year of study, possibly because of to geologic nature, low content of salts, low pH value of the water of this well. Zitona and Eid gave relatively the highest counts of TVB. This might had been due to the way in which these well were used. Intermediate counts were recorded in other wells. TC counts reached their maximum in Gofa and Farhan in Autumn. Percentages of FC among the TC counts were higher also in Autum in five wells (Al-Arbaien, Haron, Zitona, Eid and Sahab). This might had had been due to the increased agricultural activities around these wells. TC counts reached their minimum in Zitona during Winter, Spring and Summer. Five families of bacteria were identified form water samples, namely: Bacillaceae, Streptococcaceae Micrococcaceae, Neisseriaceae and Enterobacteriaceae. The geological condition of each well, some meteorological factors, and inhabitants activities around the well were found to play an important role in variability of TVB, TC, and FC counts. It is suggested that the inhabitants be educated of the best and healthy ways of using water and the good healthy habits.

Antibacteriophage action on the larvicidal activity of Bacillus thuringiensis H-14 and Bacillus sphaericus against Culex pipiens.

An organically polluted mosquito breeding water was tested for the presence of bacteriophages which could inhibit the larvicidal activity of B. thuringiensis H-14 and B. sphaericus. More than one bacteriophage were isolated which could inhibit the tested bacteria. The sensitivity of the two bacterial species to 12 antibiotics was tested. Two of them, showed no antibacterial action, were selected and considered as antivirus agents in the bacteriophage assays; namely, Amoxycillin and Co-Trimoxazole. Results indicated their antivirus activity as the addition of the antibiotics to the isolated phages could permit normal bacterial growth as well as persistence of larvicidal activity against Culex pipiens larvae.

Transmission of Rift Valley fever virus by different geographic strains of Culex pipiens in Egypt.

Previous investigations have delt with colonized Cx. pipiens and RVF virus interactions. This study evaluated the vector competence of parental Cx. pipiens populations for RVF virus and investigated variations in the vector competence among different geographic strains of this mosquito in Egypt. Cx. pipiens females were fed on viremic hamsters circulating 9.4-10.5 log10 SMICLD50 of virus. Mosquito samples were freezed at different intervals extending between 0-12 days of extrinsic incubation (EI). Transmission experiments started at day 5 of EI when individual females were allowed to refeed on normal hamsters. The infection rates for the geographic strains tested ranged between 85% and 100% and the transmission rates ranged between 6% and 35%. Transmission of RVF virus to normal hamsters took place at days 9, 12, 15 and 18 of EI by the different tested Cx. pipiens strains. Transmitter females contained significantly more virus than the non-transmitters except for the strain of Giza. Most of the infected Cx. pipiens individuals were of the non-transmitting type even those with high titers. Barriers at the salivary gland level competing RVF virus transmission are probably present in Egyptian Cx. pipiens. RVG virus infection was observed to adversely affect Cx. pipiens. The present investigation revealed no geographic variations in the vector competence of Egyptian Cx. pipiens for RVF virus.