Vector competence of autogenous and anautogenous culex pipiens mosquitoes for wuchereria bancrofti

Vector competence of autogenous and anautogenous Culex pipiens derived from North Sinai Governorate, Egypt, for the human filaria parasite Wuchereria bancrofti was studied. After feeding on the same microfilaremic volunteers both biotypes were readily infected with the parasite [infection rates > 80%] and supported its development to the infective stage within 11 - 12 days. Infective rates of both autogenous and anautogenous mosquitoes were similar [> 95%]. However, autogenous Cx. pipiens developed significantly less number of infective stage larvae [4.7 +/- 1.4 1.3 / female] than did anautogenous siblings [6.7 +/- 3.6 L[3]/ female] [P < 0.05]. Moreover, autogenous females were observed to contain twice the number of L[3] larvae in the thoracic muscles and less larvae in the head region compared to autogenous counterparts. Vector competence characteristics of Cx. pipiens derived from a filariasis endemic area in Qalubiya Governorate were similar to those of anautogenous mosquitoes of North Sinai. These findings indicate that autogenous Cx. pipiens may be less efficient vector of W. bancrofti in endemic areas of Egypt

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, Phleboiomus papalasi 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

Housefly 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 surveyes revealed the followings [I] 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

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 log[10] SMICLD[50] of virus. Mosquito samples were freezed at different intervals extending between 0-12 days of extrinsic incubation [E1].Transmission experiments started at day 5 of E1 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 E1 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. RVF virus infection was observed to adversly affect Cx pipiens. The present investigation revealed no geographic variations in the vector competence of Egyptian Cx. pipiens for RVF virus

Interaction between bacterial and chemical larvicides used in mosquito control

The bacterial larvicdis "Bacillus thuringiensis H-14 and Bacillus sphaericus 15934" were biologically assayed against the 3rd instar Culex pipiens larvicide, with each other or with the conventional chemical larvicide "dieldrin". A results indicated that the larval mortality occurred when these larnicides were used simultaneously or in sequences, were found to be higher than that achieved when these preparations were used separately. So it may be assumed that, it is preferable to use these bacterial larnicides in integration with the chemical one in mosquito larval control programmes, instead of using each of them alone

Experimental transmission of wuchereria bancrofti by culex pipiens using capillary feeding technique

A capillary feeding technique was developed to provide an easy rapid method to asses L3 larvae transmission by infected Cx. pipiens under laboratory conditions. By using this technique, the infective females of Cx. pipiens to W. bancrofti infection could be separated into two groups Transmitters and non-transmitters. Also, the ability of transmitter females to eject L3 larvae and the level of infective larvae and the level of infective larvae burden can be determined. Transmission experiments carried out by this technique showed that extrinsic incubation period for transmission L3 larvae by Cx. pipiens is different from feeding technique, it was indicated that a high number of the non- transmitter females harboured L3 larvae in their proboscis, i.e. not every infective female is capable of ejecting L3 larvae during feeding and hence, is not able to infect man under experimental conditions. It was indicated that the transmitter female of Cx. pipiens is found to harbour significantly higher L3 larvae than the non-transmitter one but the number of transmitter females is less than that of non transmitter ones. Ejection of L3 larvae from the mosquito vectors during filaria transmission was tested under different stimulating media. Seven different media were tested. Based on the present results, precise informations about the preferred media that stimulate the ejection of L3 larvae from infected Cx. pipiens females were obtained. It was found that, sweat is the most preferred medium which could stimulate the ejection of infective filarial larvae [L3], followed by the mixture of sweat and blood while no ejection occurred in air medium. The third medium was a mixture of sugar solution and+ blood+then+ sugar+ rsolution+ and+ lastely+ water