Seasonal studies on commensal rats and their ectoparasites in a rural area of Egypt: the relationship of ectoparasites to the species, locality, and relative abundance of the host.

The present study was carried out in 3 villages, namely Kafr Ayoub Soliman, Kafr Ibrahim El-Aidi, and El-Sa'adat, Sharqiya Governorate, Egypt. A total of 519 rats was collected from the 3 study sites: 46.6% Rattus rattus, and 53.4% Rattus norvegicus. A total of 20,643 ectoparasites was recovered from R. rattus: 33.3% mites, 33.8% fleas, and 32.9% lice. From R. norvegicus a total of 40,997 ectoparasites was recovered: 28.9% mites, 31% fleas, and 40.1% lice. Three common mite species were recovered from both rat hosts, i.e., Ornithonyssus bacoti, Radfordia ensifera, and Laelaps nuttalli. Three common flea species were also recovered from both rat hosts, i.e., Echidnophaga gallinacea, Leptopsylla segnis, and Xenopsylla cheopis. Polyplax spinulosa was the only dominant louse species that infested both rat hosts. Rats did not show a definite breeding season, and the seasonal rat indices were generally low in different study sites. There were no significant differences between the prevalence of each of mites, fleas, and lice in both rat species. The total general indices of mites and fleas, on the other hand, was significantly higher in R. norvegicus. The general index of X. cheopis was high and ranged between 5.9 in R. rattus and 14.5 in R. norvegicus. Season-related changes were observed in the general index of each of L. segnis infesting both rat species and R. ensifera and O. bacoti infesting R. norvegicus. The prevalence and general indices of some ectoparasites showed differences related to the locality of their rat hosts. Seasonal changes in the general indices of some ectoparasites paralleled seasonal changes in the relative abundance of their rat hosts.

Effect of sex, size, and age of commensal rat hosts on the infestation parameters of their ectoparasites in a rural area of Egypt.

The present study was carried out in the Bilbeis area, Sharqiya Governorate, Egypt. A total of 127 male and 115 female black rats Rattus rattus and 124 male and 153 female Norway rats R. norvegicus was collected during the study period. A total of 20,643 and 40,997 ectoparasites was recovered from R. rattus and R. norvegicus, respectively. Three common mite species were recovered from both rat hosts: Ornithonyssus bacoti, Radfordia ensifera, and Laelaps nuttalli. Three common flea species were also recovered from both rat hosts: Echidnophaga gallinacea, Leptopsylla segnis, and Xenopsylla cheopis. Polyplax spinulosa was the only louse species that infested both rat hosts. Rats that lived more than 12 mo formed about 24 and 14% of the populations of the black and Norway rats, respectively. The prevalences and general indices of many ectoparasites were significantly higher on males than on females of both rat hosts. Seasonal differences in prevalences and general indices of many ectoparasites were recorded between the 2 sexes of both rat species. Prevalences and general indices of most ectoparasites on both rat species showed a tendency to increase with increasing size and age of rat hosts. The type and degree of correlation between prevalences and general indices on the one hand and each of body size and age on the other hand differed among the species of ectoparasites.

Synthesis and structure-activity relationships of oxamic acid and acetic acid derivatives related to L-thyronine.

Aryloxamic acids 7 and 23, (arylamino)acetic acids 29, arylpropionic acids 33, arylthioacetic acids 37, and (aryloxy)acetic acid 41 related to L-triiodothyronine (L-T3) were prepared and tested in vitro for binding to the rat liver nuclear L-T3 receptor and the rat membrane L-T3 receptor. The structure-activity relationships for these compounds are described, with 7f, 23a, 29c, 33a, 37b, and 41 showing excellent potency (IC50's of 0.19, 0.16, 1.1, 0.11, 3.5, and 0.10 nM, respectively) to the nuclear receptor and significantly lower binding affinity to the membrane receptor (IC50's > 5 microM). Some of these compounds, especially in the oxamic acid series 7 and 23, showed an unprecedented potency for methyl-substituted derivatives such as 7f and 23a. Compounds 7f and 23a showed good lipid lowering effects in rats with ED50's of 20 and 5 micrograms/kg po, respectively, and a lack of cardiac side effects in rats at doses as high as 10 and 25 mg/kg po, respectively.

Essaouira and Kala iris: two new orbiviruses of the Kemerovo serogroup, Chenuda complex, isolated from Ornithodoros (Alectorobius) maritimus ticks in Morocco.

Essaouira and Kala Iris viruses were isolated from Ornithodoros (Alectorobius) maritimus ticks parasitizing yellow-legged gulls (Larus cachinnans) on the coast of Morocco in 1979 and 1981, respectively. Serological evidence indicates that these two viruses are new members of the Chenuda complex within the Kemerovo serogroup of the genus Orbivirus. Ecological, pathological, morphological, and physicochemical properties are compatible with these findings. The infectivity of these viruses for man and animals, including seabirds, remains unknown.

Thromboxane receptor antagonism combined with thromboxane synthase inhibition. 2. Synthesis and biological activity of 8-(benzenesulfonamido)-7-(3-pyridinyl)octaonic acid and related compounds.

A series of arylsulfonamide alkanoic acids substituted with a 3-pyridinyl group along the aliphatic chain were synthesized and tested in vitro for their ability to antagonize thromboxane A2 (TxA2) receptors and inhibit thromboxane synthase. These compounds were found to potently inhibit the U 46619-induced aggregation of human platelets and to also inhibit TxA2 biosynthesis in a human microsomal platelet preparation. However, some members of the series, notably compound 21, were found to display agonist activity on the rabbit aorta TxA2 receptor. This unwanted agonist activity appeared to be related to the presence of a substituent beta to the arylsulfonamido group.

Thromboxane receptor antagonism combined with thromboxane synthase inhibition. 3. Pyridinylalkyl-substituted 8-[(arylsulfonyl)amino]octanoic acids.

A series of 8-[(arylsulfonyl)amino]octanoic acids substituted with a pyridinylalkyl group along the chain were synthesized and tested in vitro for their ability to both antagonize the binding of thromboxane A2 to its receptors and to inhibit the thromboxane synthase enzyme. This series of compounds were found to inhibit the U 46619-induced aggregation of human platelets and the U 46619-induced contraction of dog saphenous vein. The compounds also inhibited TxA2 biosynthesis in a human microsomal platelet preparation. The relative position of the pyridinylalkyl and arylsulfonamide groups had significant effects on the thromboxane receptor antagonist (TxRA) activity and thromboxane synthase inhibitor (TxSI) activity. Compounds with the pyridine ring at the 7- or 8-position of the octanoic acid side chain were weakly active as TxSI but behaved as potent TxRA at the platelet receptor for TxA2. However, these compounds were agonists at the vascular receptor. Substitution of the pyridinylalkyl group at the 2- or 3-position resulted in compounds with potent TxSI activity and weak TxRA activity. The activity profile of the compounds with the pyridinylalkyl substitution at the 4-, 5-, or 6-position was very desirable. Compound 22 with a pyridinylpropyl substituent at the 4-position was found to display extremely potent TxRA and TxSI properties.

Nucleic acid levels in the developing ovaries of Hyalomma (Hyalomma) dromedarii (Acari: Ixodidae).

Protein and nucleic acid levels from the ovaries of Hyalomma dromedarii Koch were determined during different stages of oogenesis. The concentrations of total protein, DNA, and RNA increased during oogenesis, reflecting the rapid developmental changes taking place in this tissue. Peak protein and DNA levels were reached in the fully fed females, whereas RNA level peaked slightly earlier. Ribosomal RNA (rRNA) was found to be composed of 27.0s, 17.0s, and 4.1s particles. The ratio of 27.0s to 17.0s varied within the developing ovary, yet the 27.0s/4.1s ratio remained constant. The nucleotides of total RNA and rRNA were determined, and the ratio of purine/pyrimidine equaled approximately 1 and remained unchanged during oogenesis.

Biochemical changes in Hyalomma (Hyalomma) dromedarii (Acari: Ixodidae) embryos and effect of 20-hydroxyecdysone applied to the mother.

Changes in DNA, RNA, total lipids, phospholipids, and proteins and the activity of certain enzymes and pattern of their isozymes were studied in Hyalomma dromedarii Koch during embryogenesis. Total proteins fluctuated with a net increase (P less than 0.05) on day 20. Total lipids increased during the first half of embryogenesis and then declined with a net decrease to about 60% of the original level. Total phospholipids decreased to half this original level. DNA content increased greatly during cleavage, gastrulation, and organogeny and RNA increased during cleavage and blastula formation. Glucose-6-phosphate dehydrogenase (G6PDH) activity decreased (P less than 0.05), reaching 20% of its original level on day 12. Malic acid dehydrogenase (MDH) activity remained nearly unchanged throughout embryogenesis. Lactic acid dehydrogenase (LDH) activity increased greatly, with the highest level on day 14 with no further change. Acetylcholinesterase (AchE) activity increased greatly during the first 12 d, with no significant change thereafter. Acid (ACP) and alkaline (ALP) phosphatase activity increased during the first 12 d and declined returning to the original level on day 20. Seven AchE and 5 LDH isozymes were detected during different embryogenesis stages. Two MDH, 2 ACP, 1 ALP, and 2 G6PDH isozymes were detected throughout embryogenesis. Treating the mother with 20-hydroxyecdysone was associated with increases in protein and RNA contents and G6PDH and AchE activity and with decreases in ACP and ALP activity in the embryos.

Biochemical effects of juvenile hormone III on the tick, Argas (Persicargas) arboreus (Acari: Argasidae), during embryogenesis.

The biochemical effects of juvenile hormone III (JH III) on developing embryos from treated female Argas (Persicargas) arboreus Kaiser, Hoogstraal and Kohls were examined. Exogenous JH III resulted in a decrease in total proteins (P less than 0.001) only during the first 2 d of embryogenesis. There was no significant difference (P greater than 0.05) between RNA and DNA content in eggs from control and JH III-treated females. No significant difference (P greater than 0.05) was observed between control and JH III eggs in their lipid or phospholipid contents throughout embryogenesis. A total of 14-17 protein bands and 6-8 glycoprotein bands were separated by electrophoresis during embryogenesis of A. arboreus with some differences in mobility ratio between bands from control and JH III eggs. Differences in activity and isozyme patterns of malic acid, lactic acid, glucose 6-phosphate dehydrogenase, acid phosphatase, and alkaline phosphatase were not observed during embryogenesis of control and JH III-treated A. arboreus. Differences were observed in esterase activity.

Vaginal eversion in a bat tick, Argas (Chiropterargas) boueti Roubaud and Colas-Belcour (Acari: Argasidae).

Vaginal eversion was observed in Argas (Chiropteragas) boueti. During eversion, both cervical and vestibular parts of the vagina are fully everted so that the former is anteriorly oriented, whereas the latter occupies the posterior end of the everted organ. The histology of normal and everted vaginas is described and correlated with its functional and biological significance. Vaginal eversion most likely occurs while the tick is ovipositing and may be involved in the wax-coating process of eggs by Gene's organ.

Erve virus, a probable member of Bunyaviridae family isolated from shrews (Crocidura russula) in France.

An apparently new agent, provisionally named Erve virus, was isolated in 1982 from tissues of three white toothed shrews, Crocidura russula, trapped near Saulges village in Western France. Results of virological and ultrastructural studies suggest that this virus belongs to the Bunyaviridae family and is a Bunyavirus-like agent. Serosurveys indicate that Erve virus had apparently a large geographical distribution in France and infects rodents, insectivores, wild boars (Sus scrofa), red deer (Cervus elaphus), sheep, herring gulls (Larus argentatus) and humans. Blood donors living in the vicinity of the Saulges area exhibit the highest incidence of antibody against Erve virus.

Tick-borne Kemerovo group orbiviruses in a Newfoundland seabird colony.

Five new isolates of Kemerovo group viruses were recovered from Ixodes uriae collected on Great Island, Witless Bay Seabird Sanctuary, Newfoundland, Canada, during July 1985. This brings the total number of Orbivirus isolates on Great Island to 18 isolates including the 7 from 1971 and 6 from 1972. Genomic segments of several strains were compared by polyacrylamide gel electrophoresis. The degree of variation in each segment of these viruses was calculated. Great Island and Bauline viruses exhibited a great degree of variation in dsRNA migration patterns. Great Island and Bauline genomes averaged 11.60 (SD = 0.107) and 11.69 megadaltons (SD = 0.075), respectively. Variation was observed in all 10 segments of Great Island and Bauline viruses. These findings were compared with serologic and protein gel data.

Duration of Alphavirus neutralizing antibody in naturally infected birds.

Native birds, mostly passerine species, ecologically associated with Culiseta melanura, the enzootic vector of eastern equine encephalomyelitis and Highlands J viruses in the eastern United States, were examined over a 12-year period in southeastern Massachusetts. These studies concentrated on those individual birds known, by banding returns, to be residents of large wooded swamps where both eastern equine encephalomyelitis and Highlands J viruses were known to be enzootic. Of 8,417 birds sampled, 1,227 (14.6%) were recaptured one or more times (mean 2.7 times). Antibody profiles on individuals nesting or feeding in enzootic areas were determined from serial blood samples drawn from these recaptured birds. The duration of detectable neutralizing antibody in these birds was found to be ephemeral in some species (e.g., black-capped chickadees) and extremely longlasting in others (e.g., gray catbirds, swamp sparrows). The significance of these findings to arbovirus surveillance programs is discussed.

The isolation of Meaban virus, a new Flavivirus from the seabird tick Ornithodoros (Alectorobius) maritimus in France.

Seven strains of a new Flavivirus, for which the name of Meaban virus is proposed, were isolated from the seabird tick Ornithodoros (A.) maritimus collected during 1981 and 1982 in nests of herring gulls (Larus argentatus) on islands of South Brittany, France. The new virus was compared serologically with 65 other flaviviruses including Tyuleniy virus and was found to be most closely related to, but different from Saumarez Reef virus, an agent previously isolated in Australia and Tasmania. Some general properties of Meaban virus are described and its antigenic relationships with other tick-borne flaviviruses associated with seabirds are discussed.

Association of a Sindbis-like virus with Ockelbo disease in Sweden.

An alphavirus isolated from Culiseta mosquitoes has been associated with Ockelbo disease, an exanthema arthralgia syndrome occurring in Sweden. The isolate was made from mosquitoes collected in Edsbyn (central Sweden), an area with considerable Ockelbo disease morbidity. This isolate proved to be indistinguishable from Sindbis virus by complement-fixation and hemagglutination-inhibition tests, and was antigenically related to Sindbis in plaque reduction neutralization tests. Patients with Ockelbo disease developed neutralizing antibodies to the virus in their convalescent sera, suggesting that it is the etiologic agent of the disease.