Antioxidant or pro-oxidant and glutathione transferase P1-1 inhibiting activities for Tamarindus indica seeds and their cytotoxic effect on MCF-7 cancer cell line.

BACKGROUND: The multidrug resistance (MDR) of cancer cells is a major obstacle to cancer treatment. Glutathione S-transferase Pi (GSTP1-1) catalyzes the conjugation of glutathione with anticancer drugs and therefore reduces their efficacy. Phenolic compounds have the potential to inhibit GST P1-1 activity, which is a promising goal to overcome MDR and increase the efficacy of chemotherapy. RESULTS: Three fractions (dichloromethane, ethyl acetate, and n-butanol) were prepared from Tamarindus indica seeds to determine their phenolic and flavonoid properties as well as their antioxidant/pro-oxidant properties. The n-butanol fraction displayed the highest levels of phenol ( 378 ± 11.7 mg gallic acid equivalent/g DW) and flavonoids (83 ± 6.0 mg rutin equivalent/g DW). Inhibiting effects on purified GSTP1-1 activity in human erythrocytes (eGST), placenta (pGST), and hGSTP1-1 have been studied. The n-butanol fraction was the most effective in inhibiting eGST, hGSTP1-1, and pGST with IC50 values of 3.0 ± 0.7, 4.85 ± 0.35, and 6.6 ± 1.2 µg/ml, respectively. Cellular toxicity was investigated for the T. indica n-butanol fraction on various human cancerous cell lines. The only ones affected were MCF-7 cell lines (72%) and HePG2 (52%) indicated cytotoxicity. The value of IC50 is 68.5 µg/ml of T. indica n-butanol fraction was observed compared to 1.7 µg/ml tamoxifen in MCF-7 cell lines. The combination of treatment of T. indica extract with the medicinally approved drug tamoxifen had unexpected effects; complete elimination of the cytotoxic inhibition effect of tamoxifen and the plant extract was observed. CONCLUSIONS: However T. indica extract has a cytotoxic effect on the MCF-7 cell line; in certain situations, plant products can have an opposite effect to the intended drug, which decreases the impact of the drug.

Efficacy of second-line chemotherapy after a first-line triplet in patients with metastatic colorectal cancer.

Background: Exposing patients with metastatic colorectal cancer (mcrc) to all three active chemotherapeutic agents (oxaliplatin, irinotecan, fluorouracil) has improved survival. The benefit of second-line chemotherapy after a first-line triplet is not clearly defined. We evaluated the efficacy of second-line chemotherapy in patients who had received first-line triplet therapy. Methods: The medical records of patients treated on a prospective trial of first-line triplet therapy were reviewed for second-line treatment. Univariate and multivariate analyses were performed to establish factors of prognostic significance. Results: Of the 53 patients who received first-line triplet therapy, 28 (53%) received second-line chemotherapy [13 men; 8 with a colon primary; mutant KRAS in 10, wild-type in 15, and unknown status in 3; Eastern Cooperative Oncology Group performance status (ps) of 1 in 16 patients, ps 2 in 3, ps 3 in 2, and unknown in 7; involved organs: liver in 17 patients, lung in 16, and peritoneum in 8]. Second-line chemotherapy consisted of xelox or folfox in 13 patients, xeliri or folfiri in 12, and single-agent irinotecan in 3. Concurrent bevacizumab was given in 16 patients (57%), and cetuximab, in 2 (7%). Median survival was 28.0 months [95% confidence interval (ci): 22.8 months to 33.2 months] for patients receiving second-line therapy and 23.0 months (95% ci: 13.2 months to 32.8 months) for those not receiving it. Best response was partial in 6 patients (21%), stable disease in 11 (39%), and progressive disease in 11 (39%). Median progression-free survival was 4.8 months (95% ci: 2.4 months to 9.6 months), and overall survival was 15 months (95% ci: 9.6 months to 20.4 months). Conclusions: Second-line chemotherapy after first-line triplet therapy in mcrc is feasible and suggests efficacy comparable to that reported for second-line therapy after a doublet, regardless of the agent used.

Innate Cellular Immune Responses in Aedes caspius (Diptera: Culicidae) Mosquitoes.

Mosquitoes transmit a variety of pathogens that have devastating consequences for global public and veterinary health. Despite their capacity to serve as vectors, these insects have a robust capacity to respond to invading organisms with strong cellular and humoral immune responses. In Egypt, Aedes caspius (Pallas, 1771) has been suspected to act as a bridge vector of Rift Valley Fever virus between animals and humans. Microscopic analysis of Ae. caspius hemolymph revealed the presence of phagocytic cells called granulocytes. We further evaluated cellular immune responses produced by Ae. caspius as a result of exposure to a Gram-negative, and Gram-positive bacterium, and to latex beads. After challenge, a rapid and strong phagocytic response against either a natural or synthetic invader was evident. Hemocyte integrity in bacteria-inoculated mosquitoes was not morphologically affected. The number of circulating granulocytes decreased with age, reducing the overall phagocytic capacity of mosquitoes over time. The magnitude and speed of the phagocytic response suggested that granulocytes act as an important force in the battle against foreign invaders, as has been characterized in other important mosquito vector species.

A model for the coupling of the Greater Bairam and local environmental factors in promoting Rift-Valley Fever epizootics in Egypt.

OBJECTIVES: Rift-Valley Fever (RVF) is a zoonotic mosquito-borne disease in Africa and the Arabian Peninsula. Drivers for this disease vary by region and are not well understood for North African countries such as Egypt. A deeper understanding of RVF risk factors would inform disease management policies. STUDY DESIGN: The present study employs mathematical and computational modeling techniques to ascertain the extent to which the severity of RVF epizootics in Egypt differs depending on the interaction between imported ruminant and environmentally-constrained mosquito populations. METHODS: An ordinary differential system of equations, a numerical model, and an individual-based model (IBM) were constructed to represent RVF disease dynamics between localized mosquitoes and ruminants being imported into Egypt for the Greater Bairam. Four cases, corresponding to the Greater Bairam's occurrence during distinct quarters of the solar year, were set up in both models to assess whether the different season-associated mosquito populations present during the Greater Bairam resulted in RVF epizootics of variable magnitudes. RESULTS: The numerical model and the IBM produced nearly identical results: ruminant and mosquito population plots for both models were similar in shape and magnitude for all four cases. In both models, all four cases differed in the severity of their corresponding simulated RVF epizootics. The four cases, ranked by the severity of the simulated RVF epizootics in descending order, correspond with the occurrence of the Greater Bairam on the following months: July, October, April, and January. The numerical model was assessed for sensitivity with respect to parameter values and exhibited a high degree of robustness. CONCLUSIONS: Limiting the importation of infected ruminants beginning one month prior to the Greater Bairam festival (on years in which the festival falls between the months of July and October: 2014-2022) might be a feasible way of mitigating future RVF epizootics in Egypt.

Cross-reaction of antigen preparations from adult and larval stages of the parasite Setaria equina with sera from infected humans with Wuchereria bancrofti.

Crude antigenic preparations from Setaria equina were used in ELISA and Western blotting to examine cross-reaction with human sera from areas endemic for bancroftian filariasis. Sera from normal subjects from non-endemic areas were included as negative controls. Cross-reaction was found between S. equina antigens and antibodies in the sera of Wuchereria bancrofti-infected patients, with the highest levels observed between sera of chronic infected patients and Setaria spp. crude female worm surface antigen (CFSWA). In the absence of active transmission of Setaria spp. infection, CFWSA is useful to detect chronic W. bancrofti infection before patients become symptomatic, particularly when chronic patients are known to be amicrofilaraemic. In the presence of active S. equina infection, antigens from the adult and microfilaraemic stages showed the highest degree of cross-reaction with human sera.

Impact of polystyrene beads as a mosquito control measure to supplement lymphatic filariasis elimination activities in Socotra Island, Yemen.

Lymphatic filariasis (LF) is targeted for worldwide elimination. In Yemen, all mainland implementation units met the WHO criteria for stopping mass drug administration (MDA) after 5 rounds. However, in Socotra Island these criteria were not met. Our study evaluated the efficacy of applying expanded polystyrene beads (EPBs) on the Culex population and the effect on LF transmission. Human and mosquito surveys were conducted in 40 randomly selected households in Hadibo (capital of Socotra) before and after application of EPBs. The EPBs intervention resulted in a reduction in mosquito density of 80% and a 64.3% reduction in microfilaria prevalence. The majority of interviewed households (98%) thought EPBs considerably reduced the mosquito population. After the intervention all collected pools tested negative. Application of EPBs is an effective supplement to MDA for achieving the goal of LF elimination.

Impact of polystyrene beads as a mosquito control measure to supplement lymphatic filariasis elimination activities in Socotra Island, Yemen

Lymphatic filariasis [LF] is targeted for worldwide elimination. In Yemen, all mainland implementation units met the WHO criteria for stopping mass drug administration [MDA] after 5 rounds. However, in Socotra Island these criteria were not met. Our study evaluated the efficacy of applying expanded polystyrene beads [EPBs] on the Culex population and the effect on LF transmission. Human and mosquito surveys were conducted in 40 randomly selected households in Hadibo [capital of Socotra] before and after application of EPBs. The EPBs intervention resulted in a reduction in mosquito density of 80% and a 64.3% reduction in microfilaria prevalence. The majority of interviewed households [98%] thought EPBs considerably reduced the mosquito population. After the intervention all collected pools tested negative. Application of EPBs is an effective supplement to MDA for achieving the goal of LF elimination

Cross-reaction of antigen preparations from adult and larval stages of the parasite Setaria equina with sera from infected humans with Wuchereria bancrofti

Crude antigenic preparations from Setaria equina were used in ELISA and Western blotting to examine cross-reaction with human sera from areas endemic for bancroftian filariasis. Sera from normal subjects from non-endemic areas were included as negative controls. Cross-reaction was found between 5. equina antigens and antibodies in the sera of Wuchereria bancrofti-infected patients, with the highest levels observed between sera of chronic infected patients and Setaria spp. crude female worm surface antigen [CFSWA]. In the absence of active transmission of Setaria spp. infection, CFWSA is useful to detect chronic W. bancrofti infection before patients become symptomatic, particularly when chronic patients are known to be amicrofilaraemic. In the presence of active 5. equina infection, antigens from the adult and microfilaraemic stages showed the highest degree of cross-reaction with human sera

Quantitative assessment of posture stability using computerised dynamic posturography in type 2 diabetic patients with neuropathy and its relation to glycaemic control.

INTRODUCTION: Patients with diabetic neuropathy have an imbalance, which comes with a higher risk of falls. The aim of this study was to assess posture stability using computerised dynamic posturography in type 2 diabetics mellitus patients with neuropathy as well as its relation to glycaemic control. METHODS: 54 type 2 diabetics mellitus patients with peripheral neuropathy were recruited, together with 18 type 2 diabetics mellitus patients without peripheral neuropathy acting as the control group. The first group was divided into two subgroups according to glycaemic control assessed by HbA1c (A1c), the first subgroup comprising 24 patients had good glycaemic control with A1c less than or equal to seven percent and the second subgroup with 30 patients had poor glycaemic control with A1c more than 7 percent. The postural stability was evaluated using dynamic posturography. RESULTS: The composite equilibrium score, sensory organisation test 1, 2 and 3 conditions were significantly lower in the neuropathic group as compared to the non-neuropathic group (p-value is less than 0.001). A1c was significantly correlated with the composite equilibrium score in the neuropathic group with poor glycaemic control (r-value equal to -0.395) but not correlated in the neuropathic group with good glycaemic control (r-value equal to 0.151). CONCLUSION: Posture instability in type 2 diabetic patients with peripheral neuropathy reflects an impairment of the somatosensory system; also, poor glycaemic control resulted in more posture instability. The early detection of imbalance using dynamic posturography and achieving good glycaemic control may be of great help in the prevention of falls in such patients.

Human antibody responses to Wuchereria bancrofti infective larvae.

Human IgG antibody responses to Wuchereria bancrofti third stage infective larvae (L3) surface and somatic antigens were studied by indirect immunofluorescence (IFA) and immunoblot with endemic Egyptian sera (n = 115) with the aim of identifying targets of protective immunity. Human sera variably recognized 14 major bands in L3 by immunoblot. The statistical significance of group differences in antibody prevalence was assessed by the chi-squared test. Children and young adults (aged 10-20 years) tended to have antibodies to more L3 somatic antigens than older adults, with significant differences for bands at 66, 60 and 5 kDa. Infected subjects had more consistent antibody responses to antigens at 55, 50 and 6 kDa than endemic normal subjects with negative serum filarial antigen tests, who are presumed to be uninfected. A 5 kDa antigen was preferentially recognized by the latter group. Antibodies to L3 surface antigens were equally prevalent in uninfected children (75%) and adults (90%) but less prevalent in people with microfilaremia (38%) than in amicrofilaremic subjects with or without filarial antigenemia (81%) (P < 0.001). IFA-positive sera showed significantly enhanced recognition of antigens at 66, 40 and 14 kDa in immunoblots relative to IFA-negative sera. Additional studies are needed to further characterize antigens identified in this study and to establish whether they are indeed targets of protective immunity in humans.

Host feeding of mosquitoes (Diptera: Culicidae) associated with the recurrence of Rift Valley fever in Egypt.

In 1993, Rift Valley fever (RVF) virus reappeared in Egypt. We determined the prevalence and feeding patterns of mosquitoes in 5 villages where the virus was active. Of 10 species recovered, Aedes caspius (Pallas), Culex pipiens L., Cx. antennatus (Becker), and Cx. perexiguus Theobald constituted 99% of > 35,000 mosquitoes captured in dry ice-baited CDC light traps. Ae. caspius was most prevalent, except at Nag' El Hagar where it was replaced by Cx. perexiguus. Cx. pipiens ranked 2nd, except at Nag' El Ghuneimiya, where it was replaced by Cx. antennatus. Most blood meals analyzed by an enzyme-linked immunosorbent assay reacted to > or = 1 antiserum. Cx. pipiens was mainly anthropophagic, and therefore may have been the main vector of RVF virus among humans. Ae. caspius feeds were chiefly from humans, bovines, and equines. Cx. antennatus and Cx. perexiguus fed generally on bovines. Mixed blood meals from humans and RVF virus susceptible animals were identified in the predominant mosquitoes. Prevalence and host selection, as well as predicted probability for a blood meal being interrupted, indicated that Ae. caspius may have served as a bridge vector between humans and bovines in 4 of the villages. Cx. perexiguus may have played this role at Nag' El Hagar. Because potential vectors are abundant, susceptible domestic animals are associated closely with humans, and surveillance of imported livestock is not systematic, we conclude that RVF virus sporadically will recur in Egypt.

Filariasis transmission potential of mosquitoes to humans of different age groups.

Age-specific levels of Wuchereria bancrofti infection determined by microfilaremia in filarious 10 to 60 years old males from endemic village revealed that microfilaria intensity was higher in younger age, presumably because of increased vector biting rate of younger individuals. Out of 1334 Cx. pipiens captured while attempting to bite 51 child-adult bait pairs, 54.0% selected a host in the 10-15 age group. Biting preference towards children was more evaluated (79.2%) later than earlier in the night. Frequency distribution of age-specific biting collections indicated that 62.7% recorded exceeding numbers of bites on children, 21.6% adult biting, and 15.7% equal biting of one of the baits in the pair. Furthermore, 21.6% of the children were exposed to nightly bites ranging from 21 to 64 and only 7.8% of the adults experienced from 21 to 85 bites. Mosquito biting intensity averaged 14.2 and 11.6 bites/night for children and adults respectively. Children experienced 22.4% more bites per night than adults. Thus, children are more exposed to filaria infection and seem to represent an important source of infection. It is concluded that attempts at widespread control of filariasis in the densely populated Nile Delta, where youngsters may account for an immense proportion of the local population, should concentrate on immatures.

A polymerase chain reaction-based assay for detection of Wuchereria bancrofti in human blood and Culex pipiens.

Human blood samples and indoor-resting Culex pipiens were collected in 33 randomly selected houses from different sectors of a village in the Nile Delta of Egypt which was endemic for Wuchereria bancrofti. Blood was also collected from subjects with no history of living in filarial endemic areas. Human blood samples were divided and assessed by both membrane filtration and polymerase chain reaction (PCR). Similarly, mosquito samples were assessed by both dissection and PCR. Blood pools representing each household were tested by PCR. If a pool gave a positive result, then individual blood specimens were also tested by PCR. Of the 33 houses tested, both membrane filtration and blood pools assayed by PCR identified 14 (42.4%) 'infected houses'. PCR detected parasite deoxyribonucleic acid (DNA) in blood pools from an additional 3 households that gave negative results by membrane filtration. Of 178 endemic blood samples tested by membrane filtration, 22 (12.3%) had microfilariae and all were individually positive by PCR. Although microfilaria counts were lower in blood collected during the day than in night-collected blood, the PCR results were consistent, regardless of time of collection. All non-endemic blood samples were negative by PCR. Among the 33 houses rested, mosquito pools assayed by PCR identified 17 (51.5%) as 'infected households'. Of these, 8 houses (47%) contained at least one microfilaraemic resident. One 'infected household' was identified by mosquito dissection. We concluded that PCR is a powerful epidemiological tool for screening villages for the prevalence of W. bancrofti. PCR detection of W. bancrofti DNA in blood-fed mosquitoes could be used initially to locate endemic areas with transmission of bancroftian filariasis. PCR detection of W. bancrofti DNA in blood collected during the day could then be used to assess W. bancrofti infection rates.

Parasite antigenemia without microfilaremia in bancroftian filariasis.

The term "endemic normal" in the context of filariasis refers to people who are amicrofilaremic and free of clinical signs or symptoms of filariasis despite regular exposure to the parasite. Some sera from endemic normals contain soluble Wuchereria bancrofti antigens that are detectable by enzyme-linked immunosorbent assay. We now report evidence that filarial antigenemia in these people is not an artifact and that it is indicative of active W. bancrofti infection. Filarial antigenemia was first detected within one month of the onset of microfilarial patency in experimentally infected primates. Human sera from antigen-positive endemic normals contained the same filarial antigens (by Western blot) as sera from people with microfilaremia. Sera from antigen-positive endemic normals also contained significantly higher levels of immunoglobulin G4 antibodies to native and recombinant filarial antigens than sera from antigen-negative controls matched for age and sex. The epidemiology of filarial antigenemia in endemic normals was studied with sera from a population-based study of filariasis in an Egyptian village with a microfilaria prevalence of 29%. Seventeen percent of endemic normals had antigenemia, and this group comprised 11% of the total village sample. Filarial antigenemia was significantly more common in endemic normals more than 30 years of age than in younger people. These results suggest that amicrofilaremic and asymptomatic W. bancrofti infections are relatively common in endemic areas. Additional studies are needed to determine the clinical significance, prognosis, and optimal management of such infections.

Uptake and development of Wuchereria bancrofti in Culex pipiens L. and Aedes caspius pallas.

Studies were conducted to compare early phenomena associated with W. bancrofti infection and further development in the filaria vector Culex pipiens and the refractory mosquito Aedes caspius. Ingestion rates evaluated immediately after simultaneous feeding on an infected human were 69.1% for 43 Cx. pipiens and 35.7% for 28 Ae. caspius. The observed number of mf ingested by either mosquito did not vary significantly (2.7 +/- 1.4, and 2.3 +/- 0.9, respectively) and, based on the size of the blood meal ingested (2.8 and 2.3 microliters respectively), a two-fold mf concentration factor was recorded for both species. Blood ingested by Cx. pipiens (N = 16) and Ae. caspius (N = 10) clotted within 120 and 90 min post-feeding respectively. The time difference observed, however, did not affect significantly the rates of migration into the hemocele (56 and 67% respectively). Comparison of initial infection rates with those obtained after the extrinsic incubation period of the parasite was completed, indicated that the proportion of infected Cx. pipiens was reduced by 3.9% and that of Ae. caspius by 30.0%. Furthermore, the observed infectivity ratio of 265 Cx. pipiens that had an infective blood meal was 0.74 and only 0.009 for 70 Ae. caspius. It is concluded that refractoriness of Ae. caspius to W. bancrofti is expressed through the feeding mechanism itself, by severely limiting the mf ingestion rate, and through physiological processes that inhibited the development of ingested worms.

Host-parasite relationships of Wuchereria bancrofti and mosquito hosts, Culex pipiens L. and Aedes caspius pallas.

We compared the defense mechanisms directed against Wuchereria bancrofti by a filaria susceptible mosquito, Culex pipiens, and a refractory one, Aedes caspius. The reciprocal deleterious effects of both the mosquito host and its parasite are reported. Anatomical and histological examinations of mosquitoes revealed minor differences in the general structure of the foregut of either species. The cibarial pump of Ae. caspius, however, lacked a cibarial armature and damage inflicted to some of the microfilariae (mf) ingested by this mosquito was not mechanical. In contrast, the cibarial armature of Cx. pipiens consisted of 24 delicate teeth which did not seem to affect ingested mf. The peritrophic membrane (pm) did not constitute a significant barrier to mf migrating through the midgut wall of either mosquito. Indeed, mf forced their way out into the hemocoel, immediately after they have been ingested, and up to 60 min post-feeding, when the pm was still thin and soft. It hardened 16 h post-feeding. Traversing mf perforated the pm and displaced the basement membrane. Within the thorax of Cx. pipiens, the parasite completed its development synchronously. In contrast, mf ingested by Ae. caspius did not develop beyond the sausage stage, and many of these larvae were vacuolated. In both mosquitoes, parasitized thoracic muscle fibers were tunnelled and, only in Ae. caspius, their nuclei were pyknotic. No worm encapsulation or melanization was observed in either mosquito. It is concluded that defense lines to invading parasites in Cx. pipiens are insignificant, and that in Ae. caspius, the main barrier to parasite development resides within the thoracic muscles. In the absence of cellular evidence, it is suggested that such a barrier is physiological in nature.

Vector competence of Egyptian mosquitoes for Rift Valley fever virus.

Reintroduction of Rift Valley fever (RVF) into Egypt in 1993 raised concerns about the potential for Egyptian mosquitoes to transmit the virus. We evaluated the ability of Aedes caspius, Culex pipiens, Cx. antennatus, Cx. perexiguus, Cx. poicilipes, and Anopheles pharoensis collected in the Aswan area and Cx. pipiens collected in the Nile Delta to transmit RVF virus. All mosquito species tested were susceptible to RVF virus infection, with An. pharoensis and Ae. caspius being the most sensitive to infection. However, none of 12 An. pharoensis, including 10 with a disseminated infection, transmitted RVF virus by bite. In contrast, nearly all Cx. pipiens (87%, n = 15) and Cx. perexiguus (90%, n = 10) with a disseminated infection transmitted virus. Overall transmission rates for mosquitoes exposed to hamsters with a viremia > or = 10(7) plaque-forming units/ml were Ae. caspius, 20% (n = 5); Cx. pipiens, 7% (n = 102); Cx. antennatus, 7% (n = 30); Cx. perexiguus, 11% (n = 9); and An. pharoensis, 0% (n = 7). Based on abundance, susceptibility to infection, ability to transmit virus, and feeding behavior, Ae. caspius appeared to be the most efficient vector of the Egyptian mosquitoes evaluated. While less susceptible than Ae. caspius, Cx. pipiens, Cx. antennatus, and Cx. perexiguus were also potential vectors during this RVF outbreak in Egypt.

Identification of endemic foci of filariasis by examination of mosquitoes for microfilariae.

Studies were conducted in the Nile Delta of Egypt to determine the feasibility of detecting Wuchereria bancrofti microfilariae (Mf) in mosquitoes as a primary surveillance method for the identification of filariasis-endemic villages. Initial experimental studies evaluated the ingestion, survival, and migration rates of W. bancrofti Mf in Culex pipiens and Culex antennatus after mosquitoes were fed on infected volunteers. In 2 villages, 1,684 bloodfed mosquitoes were dissected during the night immediately after collections inside houses. In the village of Kafr Tahoria, Mf were found in 27 of 519 Cx. pipiens and in one of 8 Anopheles pharoensis. In Tahoria, Mf were detected in 7 of 799 Cx. pipiens and in one of 302 Cx. antennatus. Identifying filariasis-endemic villages based on the detection of Mf in mosquitoes may be a useful strategy for epidemiologic studies or for filariasis control programs.

Host-feeding patterns of Culex pipiens and Cx. antennatus (Diptera: Culicidae) from a village in Sharqiya Governorate, Egypt.

Host-selection patterns of mosquitoes were determined over a 1-yr period at Abu Heif, a village in Sharqiya Governorate, Egypt, that has had a history of Rift Valley fever virus (RVFV) transmission. Culex pipiens L. and Cx. antennatus Becker were the most common mosquito species collected, and 8,252 blood meals from both species were analyzed by a precipitin technique. Host availability was estimated by a monthly census of human and animal populations. Both mosquito species exhibited opportunistic endophagic behavior. In bedrooms, 79% of Cx. pipiens fed on humans, compared with 53% of the Cx. antennatus. In animal sheds, 35% of Cx. pipiens and 68% of Cx. antennatus fed on sheep or goats. Cx. pipiens was primarily anthropophilic (forage ratio = 2.7) whereas Cx. antennatus was mainly an ovine feeder (forage ratio = 2.4). These findings indicated that both species probably were involved in the transmission of RVFV in Sharqiya Governorate during the epidemics of 1977 and 1978, Cx. pipiens being mainly responsible for transmission to humans, and Cx. antennatus for transmission among domestic animals. The persistent custom of keeping sheep and goats inside human dwellings, combined with the opportunistic host selection by the local mosquitoes, continues to make this area receptive to RVFV transmission.