Prevalence of vectors of the spotted fever group Rickettsiae and murine typhus in a Bedouin town in Israel.

A survey of the vectors of spotted fever group Rickettsiae and of murine typhus was carried out in Rahat, a Bedouin town in the Negev Desert, where the diseases are endemic. Houses with known cases of spotted fever group Rickettsiae or murine typhus were compared with those without reported clinical cases. A neighboring Jewish community, Lehavim, where no cases of spotted fever group Rickettsiae and murine typhus were reported in recent years, was used as a control. In the houses of patients with spotted fever group Rickettsiae in Rahat, an average of 7.4 times more ticks were found than in control houses. Out of 190 ticks isolated from sheep and goats or caught by flagging in Rahat, 90% were Rhipicephalus sanguineus (Latreille), 7.9% Rhipicephalus turanicus Pomerantzev, and 2.1% were Hyalomma sp. In the houses of patients with murine typhus, three times more rats were caught and, on the average, each rat was infested with 2.2 times more fleas than rats in the control houses. Out of 323 fleas collected from 35 Norwegian rats (Rattus norvegicus Berkenhout), 191 were Xenopsylla cheopis Rothschild and 132 Echidnophaga murina Tiraboschi. Thus, there was a six to seven times higher probability of encountering a tick or flea vector where infections had occurred than in control houses in Rahat. The percentage of rats seropositive to Rickettsia typhi was similar in study and control households (78.3 and 76.2, respectively). In the control settlement, Lehavim, only three Mus musculus L. were caught, which were not infested with ectoparasites and their sera were negative for murine typhus. Out of 10 dogs examined in this settlement, 15 R. sanguineus and eight specimens of the cat flea (Ctenocephalides felis felis Bouché) were isolated. No rats were caught in this settlement. These data indicate that there is a correlation among the density of domestic animals, their ectoparasites, and the incidence of spotted fever group Rickettsiae and murine typhus in Rahat.

Louse comb versus direct visual examination for the diagnosis of head louse infestations.

The techniques used for diagnosis of head louse (Pediculosis capitis) infestation are a source of controversy. Most epidemiologic and diagnostic studies have been done using direct visual examination. The main objective of this study is to compare the efficacy of direct visual examination versus the louse comb method. The hair of each child was examined twice; one team used a screening stick and another team used a louse comb. Seventy-nine boys and 201 girls, 7-10 years old were examined. Examination with a louse comb found that 25.4% of the children were infested with both lice and nits, while another 31.3% had nits only. Boys were significantly less infested with lice and nits than girls (lice: 15.2 and 29.6%; nits: 21.5 and 35.4%, respectively). The infestation rate with lice and nits was significantly higher in children with long (68.9%) and medium-length (63.9%) hair than in children with short hair (44.0%) (p < 0.01). Direct visual examination found that 5.7% of the children were infested with both lice and nits, and another 49.0% with nits only. The average time until detection of the first louse was 57.0 seconds with the comb as compared to 116.4 seconds by direct visual examination. Diagnosis of louse infestation using a louse comb is four times more efficient than direct visual examination and twice as fast. The direct visual examination technique underestimates active infestation and detects past, nonactive infestations.

Maggot therapy for the treatment of intractable wounds.

BACKGROUND: Fly maggots have been known for centuries to help debride and heal wounds. Maggot therapy was first introduced in the USA in 1931 and was routinely used there until the mid-1940s in over 300 hospitals. With the advent of antimicrobiols, maggot therapy became rare until the early 1990s, when it was re-introduced in the USA, UK, and Israel. The objective of this study was to assess the efficacy of maggot therapy for the treatment of intractable, chronic wounds and ulcers in long-term hospitalized patients in Israel. METHODS: Twenty-five patients, suffering mostly from chronic leg ulcers and pressure sores in the lower sacral area, were treated in an open study using maggots of the green bottle fly, Phaenicia sericata. The wounds had been present for 1-90 months before maggot therapy was applied. Thirty-five wounds were located on the foot or calf of the patients, one on the thumb, while the pressure sores were on the lower back. Sterile maggots (50-1000) were administered to the wound two to five times weekly and replaced every 1-2 days. Hospitalized patients were treated in five departments of the Hadassah Hospital, two geriatric hospitals, and one outpatient clinic in Jerusalem. The underlying diseases or the causes of the development of wounds were venous stasis (12), paraplegia (5), hemiplegia (2), Birger's disease (1), lymphostasis (1), thalassemia (1), polycythemia (1), dementia (1), and basal cell carcinoma (1). Subjects were examined daily or every second day until complete debridement of the wound was noted. RESULTS: Complete debridement was achieved in 38 wounds (88.4%); in three wounds (7%), the debridement was significant, in one (2.3%) partial, and one wound (2.3%) remained unchanged. In five patients who were referred for amputation of the leg, the extremities was salvaged after maggot therapy. CONCLUSIONS: Maggot therapy is a relatively rapid and effective treatment, particularly in large necrotic wounds requiring debridement and resistant to conventional treatment and conservative surgical intervention.

Ticks as the main target of human tick-borne disease control: Russian practical experience and its lessons.

For several decades, the emphasis in human tick-borne disease control has been on the epidemiologically-based preventive (non-specific) approach where tick vectors were the main target of control impact. A long-term, large-scale campaign for controlling the taiga tick Ixodes persulcatus, the main vector of tick-borne encephalitis, was carried out in Russia in the 1950s to 1970s. The practical experience accumulated during that campaign could be of great value for the current development of strategies of tick-borne disease control. A general scheme of human protection from tick-borne diseases is presented where the required investment into protection is proportional to the risk of human infection and particular strategies of control and protection are differentiated. The critical point in the preventive approach is the necessity of radical tick suppression in the areas with the highest risk of human infection that can be successfully achieved only through chemical treatment directed at the eradication of the entire tick population. The following aspects are considered: the tick population (or a group of populations) as a desirable target of any acaricidal impact (biological and geographic aspects, the fate of the population after treatment); the advantage of long-term planning for control campaigns; and the influence of acaricidal impact on foci of tick-borne diseases. The conception of losses of potential pesticidal impact efficacy provides much room for the improvement of conventional tick control strategies making them more efficient and safe to the environment. The current tendency to make humans the main target of control through vaccination and/or medical treatment (specific approach) does not fit the objectives of effective human protection from tick-borne diseases, especially because of a tick population's ability to carry and transmit more than one pathogen over the same area.

[Maggot therapy for gangrene and osteomyelitis].

5 patients with diabetic-foot were treated by maggot therapy. The most serious case was in a 75-year-old man who had gangrene and osteomyelitis of the right foot. Proteus mirabilis, Enterococcus sp., Providencia stuartii and Staphylococcus spec. (coagulase positive) were isolated from lesions which did not respond to antibiotic therapy. The patient had twice refused amputation but agreed to maggot therapy. Larvae of the sheep blowfly Phoenicia (Lucilia) sericata were used for twice-weekly treatment over a period of 7 months. Sterile larvae were applied to the wound and replaced every 3-4 days. After 4 months of treatment, the necrotic tissue around the toes and on the sole of the foot detached from the healthy tissue. During the last 3 months of treatment the larvae removed the remaining infected tissue. As therapy progressed, new layers of healthy tissue covered the wound. The offensive odor associated with the necrotic tissue and the intense pain in the foot decreased significantly. At the end of therapy, during which there were no complaints of discomfort, he was able to walk. In the 4 other patients who had relatively superficial gangrene, the maggots debrided the wounds within 2-4 weeks. Thereafter treatment was continued with antibiotics. Maggot therapy can be recommended in cases of intractable gangrene and osteomyelitis, when treatment with antibiotics and surgical debridement have failed.

Rhipicephalus sanguineus and R. turanicus (Acari:Ixodidae): closely related species with different biological characteristics.

Life cycle parameters of 2 closely related tick species, Rhipicephalus sanguineus Latreille and R. turanicus Pomerantsev, were studied under laboratory conditions. Both Rhipicephalus, which have small adults, demonstrated the same adaptations as large tick species inhabiting deserts and semideserts: high reproductive rate, decrease in egg size, and an increase in interstage growth to compensate for the smaller size at birth. Pronounced quantitative differences between both species were discerned in relation to these adaptations. Female R. turanicus produced twice as many eggs as R. sanguineus which was facilitated by the greater amount of blood engorged by females and by the smaller egg weight in R. turanicus as compared with R. sanguineus. In all developmental stages, the weight increase from unfed to fed ticks was greater in R. turanicus than in R. sanguineus (23% higher in larvae, 118% in nymphs, and 26% in females). The increase in weight in R. turanicus from the unfed larva (0.013 mg) to the unfed female (3.31 mg) was 254-fold, and in R. sanguineus it was 127-fold (from 0.021 to 2.54 mg). In nymphal R. turanicus, the higher density and the greater height of the dorsal epicuticular folds, as well as procuticular indentations found inside the folds allow this tick to stretch its alloscutum during blood engorgement to a greater extent than R. sanguineus. The rates of blood ingestion (for nymphs and females), egg maturation, and metamorphosis were 1.1-1.7 times greater in R. turanicus than in R. sanguineus. A life cycle strategy with both a higher reproductive rate and faster development in R turanicus may be explained by its greater dependence on environmental factors than that in R. sanguineus.

Human toxicosis caused by the tick Ixodes redikorzevi in Israel.

The clinical symptoms of a tick toxicosis caused by Ixodes redikorzevi in northern Israel are described. The patient was a nine-year-old Arab boy from an agricultural village who was admitted to a local hospital and had been suffering for 4 days from fever and torticollis. A partially engorged female tick was removed from the nuchal area of the scalp, and the symptoms disappeared within 2 hours. Morphometrical measurements indicated that the tick was attached to the skin for 3-4 days.

Prevalence of spotted fever group rickettsiae in ticks from southern Israel.

The prevalence of spotted fever group rickettsiae was studied in questing ticks collected from southern Israel. Ticks were examined from an agricultural settlement (kibbutz Ze'elim), an endemic site for Mediterranean spotted fever, and from another kibbutz (Re'im) in an adjacent area where the disease has not been reported. Ticks were collected by flagging and CO2 traps from vegetation inside and outside the settlements during 1989/1990 and 1994. In Ze'elim, 98% of the ticks collected were brown dog tick, Rhipicephalus sanguineus (Latreille), whereas in Re'im the predominant species was Rhipicephalus turanicus Pomerantzev (84.6%), with 11.8% of the ticks R. sanguineus and 3.6% Hyalomma excavatum Koch. The presence of rickettsiae in the hemolymph of the ticks was demonstrated by immunofluorescence using polyclonal antibodies made against the human pathogenic Moroccan strain of Rickettsia conorii. Of 549 ticks examined in 1989/1990 from Ze'elim, 7.3% were positive for spotted group rickettsiae, and in Re'im 2.2% of 156 R. turanicus were positive. In 1994, 51 out of 186 (27.4%) ticks in Ze'elim and 3 out of 115 (2.6%) ticks in Re'im were positive. All 20 specimens of H. excavatum were negative for spotted fever group rickettsiae. To our knowledge, this is the 1st report of spotted fever group rickettsiae in R. turanicus from Israel.

Physiological age of ixodid ticks: aspects of its determination and application.

This review analyzes 30 yr of data concerning physiological age of ixodid ticks. The level and state of nutritional reserves in unfed ticks has been proposed as an index of tick physiological age. The dynamics of the use of these substances reflect tick aging. Thus, physiological age of ixodid ticks is determined by estimating the irreversible changes caused by natural vital activity in the body of unfed ticks, which inevitably raises the probability of tick death. The 4 age groups used in most studies correspond to different periods in the life of unfed ticks: the postmolting development, the commencement of active life (= questing activity), the midperiod of active life, and the final period of active life. The aging of adult ixodid ticks has been studied in natural populations and laboratory colonies of different species belonging to several genera. The dynamics of age composition through the activity season observed in adult Ixodes persulcatus, I. ricinus, and Dermacentor reticulatus from field populations correlated well with the known data on the life history of these species. Physiological age was successfully used as an indicator of the patterns of tick activization (= beginning of questing activity). Tick susceptibility to acaricides was shown to increase with tick aging. The success of maintenance, reproduction, and transmission of pathogens was found to be strongly influenced by tick physiological age. The physiological age can provide information about the present physiological status of an individual tick or a group of ticks and, on this basis, predictions can be made (for example, life expectancy, degree of response to certain factors). The physiological age does not give reliable information about the past life of ticks, in particular their calendar age. In this respect, the meaning of the physiological age of ixodid ticks corresponds to the biological (physiological, functional) age of animals, as used in gerontology, and differs from the physiological age of mosquitoes and other bloodsucking dipterans. Balashov's histological method of tick age determination successfully used by many authors, remains the most appropriate, until now. However, there is ample room for further advancement of methodologies of tick age assessment. The future methods should be based on the quantitative estimation of a number of characters (test-battery) related to different organs or systems.

Permethrin resistance in the head louse Pediculus capitis from Israel.

Head lice, Pediculus capitis, were collected from children aged 3-12 years in Maale Adumin, a town near Jerusalem, after reports of control failure with the pyrethroid insecticide permethrin. A total of 1516 children were examined: living lice and eggs were found on 12.1% of the children; or another 22.8% of the children only nits were found. Twice as many girls as boys (8.1% v 4%) were infested with lice and or nits. Head lice collected from infested children were exposed to permethrin impregnated filter-papers. Log time probit mortality (ltp) regression lines were calculated for mortality data and compared to ltp lines for a similar collection of head lice made in 1989. The regression lines for the two years were significantly different, with a 4-fold decrease in susceptibility at the LT50 level between 1989 and 1994. The slopes of the lines also suggested that the 1994 population was more heterogenous in its response to permethrin than the 1989 population. In contrast, a laboratory population of body lice (Pediculus humanus) tested with the same batch of permethrin-impregnated papers showed a slight but non-significant increase in susceptibility between 1989 and 1994. The results suggest that resistance to pyrethroids has developed rapidly among head lice since permethrin was introduced in 1991 as a pediculicide in Israel.

Rhipicephalus sanguineus: observations on the parasitic stage on dogs in the Negev Desert of Israel.

Sixteen dogs were studied for infestation with R. sanguineus in Kibbutz Ze'elim in the northwestern part of the Negev Desert over a period of one year. The mean number of ticks per dog per month was 16.4. The majority of the ticks were adults: males (48.6%) and females (34.4%). The ears and abdomen of the dog were the predilection sites for the ticks. Male ticks were more abundant on the ears, whereas female ticks were more abundant on the ears and the abdomen. A strong correlation between tick numbers and the ambient temperatures was found. The mean percentage of dogs infested in the winter months was 16.6% and increased in the summer months to 34.4%. During winter, ticks were found more often on the ears and head of their hosts whereas in summer they were distributed mainly on the ears, head and abdomen. The male:female ratio was higher in winter (2.3:1) than in summer (1.1:1).

Ability of successful attack in two species of ixodid ticks (Acari: Ixodidae) as a manifestation of their aggressiveness.

Patterns of attacking hosts by two closely related species of ixodid ticks (Ixodes persulcatus and I. ricinus) were compared in parallel field tests. The ability of active unfed adults of both sexes to adhere to a flannel flag dragged over grass vegetation and to remain on the flag during this process were estimated. The tests were conducted under two temperature conditions, 6-10 degrees C and 17-22 degrees C. In all test versions, adults of I. persulcatus were more successful both in adhering to the flag and in remaining on it. There were no consistent differences between males and females of the same species. The results demonstrated a differing ability of successful attack in both tick species. This ability is a complex derivative of the tick activity and aggressiveness. An attempt is made to analyse the latter phenomenon, which is considered as a general one for all bloodsucking arthropods. The aggressiveness of arthropods should be taken into account as one of the leading factors influencing the sampling results.

Host substitution by Ixodes persulcatus (Acari: Ixodidae) larvae in the years of deep depression in the abundance of small mammals.

A phenomenon of host substitution by the taiga tick (Ixodes persulcatus) larvae was observed by the authors in the western part of the Soviet Far East. In the mountain forests where the highest abundance of I. persulcatus was found, larvae usually fed on small mammals (primarily on Clethrionomys rufocanus, C. rutilus and Apodemus speciosus). Numerous larvae were found, however, on the mountain hare (Lepus timidus) in the years of deep depression in the abundance of small mammals. The host substitution is considered as one of the mechanisms stabilizing the abundance of I. persulcatus adults.

Genetic control and expression of the major ejaculatory bulb protein (PEB-me) in Drosophila melanogaster.

PEB-me is a predominant protein of mature Drosophila melanogaster ejaculatory bulbs. It is resolved into four or five closely spaced subfractions (apparent molecular weight 35-39 kD) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Four electrophoretic variants of PEB-me differing in apparent molecular weight by 200-800 daltons were found. These appear to be controlled by four alleles of a gene (peb) located by recombination and deletion mapping to the 60F1-2 region of chromosome 2. A minor ejaculatory bulb protein of ca. 80 kD (hPEB) was found to be immunochemically related to PEB and possibly encoded by peb. PEB is not detected by immunoblotting techniques in virgin females, in male tissues other than the ejaculatory bulb, or during developmental stages preceding the formation of this organ. The results of transplantations of genital imaginal discs and of immature ejaculatory bulbs between two strains having different PEB alleles suggest that the ejaculatory bulb is the site of PEB synthesis. In flies mutant for tra, tra-2, dsx, or ix, tissue specificity of PEB localization is retained and the protein is found whenever the ejaculatory bulb is formed, regardless of the chromosomal sex of the fly. The protein is transferred into the female genital duct during mating, where it can be detected for up to 12 hr. Possible functions of PEB in Drosophila reproduction are discussed.