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.).

Enhanced sensitivity for detection of coronary artery disease by addition of atropine to dobutamine stress echocardiography.

Patients undergoing dobutamine stress echocardiography often take beta antagonists which limit heart rate response and sensitivity in the test for detection of coronary artery disease. The aim of this study was to assess the effect of the addition of atropine to dobutamine stress echocardiography on clinical, electrocardiographic and echocardiographic outcomes. Dobutamine stress echocardiography was performed starting at and increasing every 3 minutes with 10 micrograms/kg/min to a maximum of 40 micrograms/kg/min (stage 4), which was continued for 6 minutes. In patients not achieving 85% predicted maximal exercise heart rate and in whom the test was not judged positive on echocardiographic or electrocardiographic criteria, atropine (0.25 mg intravenously, repeated up to a maximum of 1 mg if necessary) was added and dobutamine continued for up to a further 5 minutes, or until an adequate heart rate was achieved or the test was stopped because of chest pain or electrocardiographic changes. Of 80 consecutive patients undergoing dobutamine stress echocardiography within 2 weeks of coronary angiography, 49 required atropine (group A) and 31 required only dobutamine (group B). After dobutamine alone, heart rate (mean +/- SD) was higher in group B than in group A: 129 +/- 20 vs 90 +/- 18 beats/min, p less than 0.0001; but after the addition of atropine, heart rate in group A increased to 120 +/- 20 beats/min. Overall sensitivity for the detection of coronary disease was 70%, 95% confidence interval (CI) 55 to 83%; after the addition of atropine, sensitivity for group A was 65%, 95% CI 45 to 81%; in group B, sensitivity was 81%, 95% CI 54 to 96%.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Dobutamine stress echocardiography before and after coronary angioplasty.

Myocardial function was assessed by stress echocardiography in 28 patients before and after successful elective coronary angioplasty. Dobutamine stress echocardiography was performed using up to 40 micrograms/kg/min, followed by the addition of atropine in 20 patients to achieve 85% of the predicted maximal exercise heart rate. The initial studies were performed 1 day before and the second ones within 3 days (mean 1.3) after angioplasty. Peak heart rates and systolic blood pressures were the same for the 2 studies. The frequency of dobutamine-induced new wall motion abnormalities decreased from 20 (71%) before to 4 (14%) after angioplasty (p less than 0.0001). Before angioplasty, wall motion score index (an indicator of left ventricular wall motion, an increase in which indicates impaired wall motion due to myocardial ischemia) increased from 1.06 at rest to 1.23 at peak stress (p less than 10(-6)), but there was no significant increase in this index in the study after angioplasty. Before angioplasty, 14 patients (50%) developed chest pain during the stress test compared with 6 (21%) after angioplasty (p = 0.05), and before angioplasty, the stress test was stopped before the target heart rate was achieved, because of symptoms, ST-segment change or severe new wall motion abnormality in 14 patients compared with 7 after angioplasty (p = 0.09). Thus, early after angioplasty there is a reduction in myocardial ischemia as assessed by dobutamine stress echocardiography.

Selection for fenitrothion--resistance in Culex pipiens L larvae (Diptera: Culicidae).

Laboratory selection of Culex pipiens larvae by fenitrothion pressure for 24 generations resulted in 25.67 fold increase in resistance to this compound. Adults resulted from the selected larvae also acquired resistance (32.3 fold) to fenitrothion. Stability of resistance was tested and indicated that regression in resistance only occurred at lower level that regression in resistance only occurred at lower level of selection. Cross resistance to malathion and DLD slightly increased by 2.1-fold and 1.25-fold respectively that may be manifestations of vigour tolerance. It is considered that the positive results obtained here increase the probability of development of such resistance in the field. However, results of cross-resistance are encouraging as they indicate that eventual development of resistance to fenitrothion does not preclude the use of other insecticides against the resistant population.

The mode of inheritance of fenitrothion resistance in Culex pipiens L. larvae (Diptera:Culicidae).

The genetics of fenitrothion resistance in Cx. pipiens larvae was studied to determine its mode of inheritance. A laboratory susceptible and fenitrothion-resistant larval strains were used. Reciprocal crosses between the resistant and susceptible strains showed an F1 generation of partial dominance with slight cytoplasmic effect. The F2 generation underwent segregation into three genotypes, viz. susceptible, hybrid and resistant in the ratio of 1:2:1. The progenies of backcrosses to resistant and susceptible parents were in a 1:1 ratio of the same phenotypes as the parents and hybrids involved. After selection, the progeny of the back-crosses to resistant parent exhibited full resistance. It is concluded that fenitrothion resistance in Cx. pipiens larvae is due to monofactorial inheritance with partial dominance and slight cytoplasmic effect.

The breeding habitats of Phlebotomus sand flies (Diptera:Psychodidae) in El Agamy, Alexandria Egypt.

A prolonged search for the breeding habitats of Phlebotomus sand flies in El Agamy, resulted in the collection of 105 newly emerged P. papatasi and P. langeroni. These flies were from poultry sheds, rubbish on stone piles and rubbish piles.

Factors affecting the human-feeding behavior of anopheline mosquitoes in Egyptian oases.

Blood meals were tested by a direct enzyme-linked immunosorbent assay (ELISA) for 424 Anopheles sergentii and for 63 An. multicolor collected in Siwa, Farafra and Bahariya oases in the Western Desert of Egypt. Both species were highly zoophilic. Human blood-feeding by An. sergentii was less common in Bahariya (2.3%) and Farafra (1.3%) than in Siwa (15.3%). A likely explanation is that large domestic animals are held at night inside houses in Bahariya and in Farafra whereas in Siwa, animals are usually housed outdoors in sheds. These patterns of An. sergentii human-feeding behavior may contribute to the persistence of low-level Plasmodium vivax transmission in Siwa in contrast to negligible or no transmission in Bahariya and Farafra.

Enzyme electrophoresis as an alternative method for separating the sympatric Leishmania vectors Phlebotomus papatasi and Phlebotomus langeroni (Diptera: Psychodidae).

Trials were conducted to determine the accuracy of separating the sympatric sand fly species Phlebotomus papatasi (Scopoli) and P. langeroni Nitzulescu by means of cellulose acetate enzyme electrophoresis. Malic enzyme, phosphoglucomutase, 6-phosphogluconate dehydrogenase, and fumarate hydratase were each evaluated in laboratory-reared and field-collected populations of the two species. Each of the four enzyme-based identifications was highly sensitive (greater than 97%) and specific (greater than 93%). Identifications based upon fumarate hydratase were in perfect agreement with morphological identifications, and evidence was obtained which indicates that this enzyme may be the most stable of the four enzymes tested. The application of enzyme-based vector identification is discussed in relation to classical and novel survey procedures for Leishmania promastigote detection in sand flies.

Interpretation of low-level Plasmodium infection rates determined by ELISA for anophelines (Diptera: Culicidae) from Egyptian oases.

Plasmodium infection rates determined by enzyme-linked immunosorbent assay (ELISA) were compared for Anopheles sergentii (Theobald) and An. multicolor Cambouliu in Siwa Oasis, Egypt, an area with low-level Plasmodium vivax transmission, and in Bahariya and Farafra, two other Egyptian oases which appear to be free of malaria. Initial testing indicated that 4.4% (23 of 518) and 0.8% (4 of 518) of the An. sergentii were positive for P. vivax and P. falciparum, respectively, and that 1.4% (1 of 71) of the An. multicolor were positive for P. falciparum. However, after two confirmational tests, only 1.2% (6 of 518) of the An. sergentii remained consistently positive for P. vivax. Initial ELISA absorbance was not a useful predictor of potential false positive reactions in the P. vivax assay. Paradoxically, the six ELISA-positive An. sergentii were from the two malaria-free oases. This study raises the question of whether ELISA-positive reactions for anopheline vector species provides unequivocal evidence for transmission in areas of low malaria endemicity.

Seroprevalence of murine typhus and fièvre boutonneuse in certain human populations in Egypt.

A study was conducted between 1984 and 1987 to determine the prevalence of Rickettsia typhi and Rickettsia conorii infections among humans residing in the Nile Delta, Suez Canal area and Nile Valley of Egypt. Serum specimens were obtained from garbage and rodent control workers, other unclassified occupational workers, and from patients with fever of undetermined aetiology. All sera were assayed for IgA + IgM + IgG (IgAMG) antibody mixture and if positive, reassayed for specific IgM antibody to rickettsia by the indirect fluorescent antibody technique. R. typhi antibody was found in 19% (33/178) of the garbage collectors, whereas only 1% (2/178) had demonstrable antibody to R. conorii. Among those with other occupations, R. typhi antibody was detected in 0.7% (2/295) and none had R. conorii antibody. The antibody prevalence rate for R. typhi among patients with febrile illness ranged from 25 to 41%, and from 2 to 15% for R. conorii, at three different locations in Egypt. In addition, IgM antibody to R. typhi was demonstrated in some patients showing symptoms compatible with rickettsial disease and in some patients who seroconverted, indicating that R. typhi was the cause of illness among some of these patients. These findings support previous observations that R. typhi and R. conorii are the causes of human rickettsial disease in Egypt, and that humans are commonly infected with R. typhi.

Feeding patterns of Phlebotomus papatasi and Phlebotomus langeroni (Diptera: Psychodidae) in El Agamy, Egypt.

Blood meals from 602 Phlebotomus papatasi (Scopoli) and 49 Phlebotomus langeroni Nitzulescu were collected in El Agamy, Egypt, and were identified using counterimmunoelectrophoresis. Blood meals were tested against specific antisera of eight vertebrate hosts (human, cat, dog, rat, sheep, goat, general avian, and general bovine). Of 597 P. papatasi collected indoors, 594 contained human blood and three had mixed blood meals (human-dog, human-rat, and human-avian). Four of five P. papatasi collected outdoors contained human blood and one contained avian blood. All 39 P. langeroni collected indoors had fed on humans. Six of 10 outdoor-collected P. langeroni had fed on human blood, 2 on dog, 1 on cat, and 1 on rat blood. Both P. papatasi and P. langeroni feed predominantly on humans in El Agamy, Egypt. The documented feeding on humans and dogs by P. langeroni supports the role of this species as the primary vector of visceral leishmaniasis at the El Agamy focus.

Estimates of Egyptian culcine longevity in nature altered by fluctuations in biting population density.

Estimates of vectorial capacity (VC) depend upon longevity of mosquito field populations, and expected longevity is estimated from the parity rate of the population. Seasonal variation in parity rates confound estimates of longevity which may not reflect actual population survival but are induced by changes in the rate of emergence of female mosquitoes. By comparing parity rates and biting activity in natural population of 2 Culicine mosquitoes, Culex pipiens and Cx. antennatus, we found that parity rate was low in the beginning of the season and high at the end. Parity rate appeared least affected during the weeks with maximal daily biting activity. We conclude that estimates of VC are most accurately determined for the two vector species studied when mosquito biting activity is maximal.

Survival estimates for adult Culex pipiens in the Nile Delta.

In an endemic area for Wuchereria bancrofti filariasis in the Nile Delta, survival of adult female Culex pipiens was estimated by parity rate, mosquito infection and infectivity rates. Infection rates and 4th instar larval populations, as well as infection and parity rates, were linearly correlated. Infectivity correlated only with parity rates. These associations corresponded to parallel changes in ambient temperature. Although survival calculated from parity rates measured longevity of both infected and non-infected Cx. pipiens, survival based on infection and infectivity was a more reliable indicator for parasite transmission.

Investigation of sampling methods for the study of Phlebotomine sandflies in Egypt.

Different sampling field techniques were investigated for the study of the natural behaviour of the sand flies in Egypt (South Sinai and Alexandria). Sampling methods were divided into two groups: the first group is techniques for catching alive flies [Active search (Aspirator), CDC-light trap; funnel trap; Fan trap and catches off bait] and the second group is techniques for collecting dead specimens [sticky traps, and illuminated sticky traps (chemical light sticky trap)]. Comparison between the efficiency of the different trapping methods for collecting sandflies indicated that the CDC light trap was the most productive type for species of the genus phlebotomus followed by the illuminated paper traps and then the sticky paper traps. Members of the Sergentomyia group showed to be more attracted to illuminated/sticky paper followed by the sticky paper and then the CDC light traps. In general, sticky paper traps are the most widely used technique for sand fly outdoor collection as it is easy to be used, unexpensive and convenient for the purpose of sandfly surveys.

Heterozygote deficiency in natural populations of Aedes caspius Pallas from Egypt.

Aedes caspius Pallas populations from the Mediterranean regions are genetically highly polymorphic, and may diverge into 2 genetically isolated forms. We examined the genetic structure of 3 mosquito populations from Faiyum oasis, using starch gel electrophoresis at 8 gene loci, from which only one was monomorphic. Genetic variability was high (A = 1.97; H = 0.12; P = 54.2, 66.7). Eleven out of 16 population--enzyme combinations with variability exhibited heterozygote deficiency from Hardy--Weinberg expectations. These results suggest that tested populations represent a mosquito complex, although no genetic divergence was detected (D = 0.012) since presumed sympatric gamodemes were sampled as a single population. It is of prime importance to detect cryptic gamodemes and to elucidate the present status of Ae. caspius, as this may greatly influence control strategies.

Development of an enzyme linked-immunosorbent assay (ELISA) for the sand fly fever viruses detection.

An Enzyme linked-immunosorbent assay (ELISA) was recently established for the detection of sandfly Naples and Sicilian viruses (SFN and SFS) from laboratory infected as well as wild caught sandflies in Egypt. Optimal dilutions of the reactants including the coating antibodies (Rabbit antiserum), detecting antibodies (Mouse antiserum), conjugate and the time used for incubation of the substrate (ABTS) were determined for both SFN and SFS viruses. The ELISA test showed to be highly specific and sensitive except for the SFN virus which cross reacted with Toscana virus. A total of 1582 sandflies, forming 54 pools (each consisted of 2-109 flies) were collected from different governorates in Egypt (North Sinai, South Sinai, Alexandria, Giza, Qualubyia, Sharkiya and Aswan) in the years 1986-1987 and 1988, and tested for virus detection by the SFN-ELISA and SFS-ELISA. Only one pool (from Giza governorate) revirus was detected. Tests were repeated two times and confirmed by the complement fixation and plaque neutralization tests. The established ELISA technique hold great promise as a routine surveillance tool, permitting rapid, simple, sensitive, specific and inexpensive assay for the detection of the sandfly fever viruses.

Anopheles sergenti (Theobald) a potential malaria vector in Egypt.

Two immunoassays for malaria sporozoite detection and identification, the immunoradiometric assay (IRMA) and the enzyme-linked immunosorbent assay (ELISA) using the species-specific monoclonal antibodies are routinely performed in our laboratory. We analyzed (573) anopheline mosquitoes of A. sergenti (463), A. pharoensis (81) and A. multicolor (29) collected from Siwa-oases and Faiyum Governorate (two known active malaria foci in Egypt), for detection of P. falciparum and P. vivax sporozoites. P. falciparum sporozoites were detected by both IRMA and ELISA tests in two A. sergenti mosquitoes (one from Siwa 1/389 = (0.26%) and one from Faiyum Governorate 1/74 = (1.35%)). No P. vivax sporozoites were detected. This finding is important in explaining the malaria transmission and provide first incrimination of An. sergenti as the responsible vector of malaria in Siwa-oasis, Egypt.

Persistence of human leishmanial antibodies in an endemic area of visceral leishmaniasis in El Agamy, Egypt.

In an endemic area of visceral leishmaniasis (VL), individuals with leishmanial antibodies that reacted in the radioimmunoassay (RIA) were retested to determine duration of leishmanial antibody retention. One fourth of adults retained antibodies for at least 10 months. At least 2/3 of asymptomatic children retained leishmanial antibodies for 5 to 7 months after detection. 2/3 of children treated for VL retained leishmanial antibodies for 5 to 7 months after treatment, while 1/3 retained antibodies for over a year. These data modify conclusions that can be drawn from a single serosurvey. Since leishmanial RIA antibodies can persist in humans for at least two transmission seasons, incidence estimates require serial serosurveys.