[Entomology of onchocerciasis. I. Entomological factors in the transmission of onchocerciasis in Mexico].
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Research activities of medical entomology in Korea can briefly be divided into three periods. During the first period (1910-1959), medical entomology research was initiated by Japanese workers, and then by U.S. Army Medical Unit personnels and a few Korean pioneers, who greatly contributed to establishing a foundation for medical entomology in Korea. During the second period (1960-1979), research activities were intensively carried out by the entomology team of the Central Malaria Eradication Service and staffs of the Division of Medical Entomology, National Institute of Health, who collaborated with WHO-Vector Ecology and Control Research Unit. During the third period (1980-present), studies were expanded to different research laboratories, such as Departments of Biology in College of Natural Sciences and Departments of Parasitology or others in Medical Schools, and study topics also became diverse. Out of 313 papers on Korean arthropods of medical importance, the majority were on mosquitoes (142 papers, 45.4%) and, next, on flies (53 papers, 16.9%). It is hard to see the future prospect of medical entomology research in Korea, since it looks pessimistic in some respects but optimistic in others. Korean medical entomologists may be quantitatively lacking, but not qualitatively behind.
The submitted paper reacts to the unsatisfactory state as regards the literary treatment, and in particular the practical application of entomology in forensic medicine and criminology. The authors draw attention to the relatively wide perspectives of the application of entomological findings in the mentioned disciplines and define more accurately some terminological and oecological problems. The core of the work is a review of important species of necrophilous insects focused on Coleoptera. This part is introduced by an outline of oecological groups of necrophilous insects, whereby emphasis is given to their claims on habitat and food and their biotopical claims. The account of species is based on the chronological sequence as the insect invade the corpse in different stages of its destruction. Attention is paid also to abiotic (in particular climatic) factors which influence the rate of destruction. As to more extensive possible applications of entomology in the above disciplines, at least the following should be mentioned: 1. Application on the basis of the trophic relationship of insects and he corpses (time of death, possibly post-mortem transport based on investigation of the entomofauna of the corpse). 2. Information on restricted hygienic habits of the dead (the presence of ectoparasitic insects). 3. Passive intoxications, possibly active intoxications by poisonous insects. 4. Insects incidentally found on clothes, motor vehicles etc. during examination. In the conclusion the authors emphasize methodical problems of collection and processing of material and outline the prerequisites for extending and improving the application of entomological findings and methods in the mentioned disciplines.
Entomological data generated in five entomological zones, of Madhya Pradesh State during 1991 including, Bhopal, Bilaspur, Gwalior, Indore and Raipur were analyzed. The entomological parameters that were studied included per man hour (pmh) density, abdominal physiology and parity status. The inferences were related to i) resting behaviour (exophily/endophily) ii) duration of indoor resting period of mosquitoes iii) man-vector contact iv) efficacy of residual insecticide and v) vulnerability of the area to focal malaria outbreaks. The data chiefly pertains to the putative malaria vector Anopheles culicifacies in all the five zones under study. The studies have brought out that A. culicifacies, traditionally endophilic and endophagic, has demonstrated radical departure in its resting and feeding behaviour. In Gwalior zone the species shows high preference for exophily. In Bhopal and Indore zones there is differential resting behaviour with respect to season. The species shows, for most part of the year exophily but is also endophilic during post monsoon period. In Bilaspur zone the species shows marked exophily and endophagy. Irrigation practices seem to have affected the mosquito population density patterns in these regions as brought out in Indore and Bilaspur zone, where high density pattern is observed between November and February. These findings have obvious implications in selecting the appropriate intervention methods and the period of spray in areas where residual spray is the method of choice for interruption of transmission.
Sixteen insect-infested cadavers were examined and analysed to evaluate the reliability of the entomological method in estimation of time elapsed since death, in relation to other medico-legal approaches. The entomological method was found statistically more reliable and superior when compared to other prevalent methods.
A set of statistical protocols is proposed for analyzing carrion-arthropod succession in forensic entomology investigations. A total of 23 carrion-arthropod data sets from temperate, tropical, desert, and coastal environments were assembled in a standard format and analyzed using randomization tests and methods derived from quantitative community ecology. The data were analyzed in three ways. First, patterns of arthropod visitation on nonhuman carcasses were analyzed in each of the 23 cases. Analysis revealed two groups of taxa: those that persist on the carcass over a single time interval (= nonreoccurring taxa, 80% of the taxa) and those that appear, leave, and reappear over time on the carcass (= reoccurring taxa, 20%). Reoccurring taxa, which can confound estimation of the postmortem interval (PMI), were found in 6 classes, 12 orders, and 29 taxonomic families of arthropods, including some forensically important taxa (for example, calliphorids, sarcophagids, histerids). The recognition that reoccurring taxa exist and that they are found in forensically important groups is an early step toward factoring in their potential importance in future entomological investigations. Second, temporal changes in the taxonomic composition of the carrion-arthropod community were studied by quantifying the degree of taxonomic similarity between pairwise combinations of time-specific samples of the succession. In 13 of the 18 illustrated cases, the midsuccessional samples, owing to their higher species richness, were taxonomically more similar to all other pairwise samples, on the average, than early and late successional samples which were poorer in species. Variability in taxonomic composition is the norm for most periods of the succession; however, in 17 of the 23 cases, some successional periods (particularly endpoint samples) revealed no changes in arthropod species composition (= matching sample-pairs). When applied to medicolegal cases, it is suggested that data sets with large fractions of matching sample-pairs should produce wider-ranging PMI estimates, on the average, than data sets with smaller fractions of matching sample-pairs. Third, Monte Carlo simulation was applied to each of the 23 assemblages to test specific hypotheses about community-wide patterns of arthropod visitation times on nonhuman carcasses. Simulation results revealed that arthropod residence times in the majority of cases (13 or 56%) followed a "clumped" succession model, whereas, the remaining 10 cases (44%) showed a more "uniform" spacing pattern of residence times on carcasses. Comparison of species accumulation curves for observed and simulated data further revealed that among the 13 "clumped" cases, most (9 or 69%) followed a "clumped, early" model (rather than "clumped, midterm" or "clumped, late" models).(ABSTRACT TRUNCATED AT 400 WORDS)
In order to assess the factors of malaria vectorial capacity and the daily reproduction rate, separate consideration is given to data from Kankiya, Northern Nigeria, concerning the incidence of vector-man contact (the man-biting rate), the vector's expectation of infective life, as reflected by the proportion of parous mosquitos under certain conditions, and the vector's man-biting habit, comprising the frequency of feeding and the human blood index. The main difficulty in the assessment of each of these factors was shown to be that of representative and adequate sampling, especially in a sprayed area. In order to compensate for deficiencies in the Kankiya data, especially with regard to the daily and cyclic survival-rates, the gonotrophic cycle and the effective sporogonic period, more complete published data on an Anopheles gambiae population in East Africa were examined, and extrapolations were made from these data in spite of the consequential risks involved.The results of the analysis show that the spraying of an area with DDT reduced the malaria vectorial capacity of Anopheles gambiae sp. B (the main vector of Plasmodium falciparum in the area) by an over-all factor of about 23 times. Nevertheless the basic reproduction rate of the disease is estimated to have averaged slightly over 20 in the sprayed area during the 6 months of the main transmission season. This is consistent with an observed recovery in the parasite rate, which had been reduced to a very low level by regular mass drug administration through the preceding dry season.The analysis was a tentative exercise in "epidemiological entomology" and it is suggested that in the postgraduate teaching of tropical hygiene, the epidemiological approach to entomology should be preferred to the classical morphological-bionomical approach.
An entomological survey was conducted in the Gambia in January 1979, during the last phase of a yellow fever (YF) outbreak which began during the previous rainy season. In the dry conditions which prevailed in January, Aedes aegypti was the only YF vector present. Two YF virus strains were isolated from females of this mosquito species caught in a village of western Gambia, where active human cases were documented. The ae. aegypti breeding sites were exclusively of the domestic type. Larval indices varied greatly from place to place, but generally appeared to correlate with the incidence of disease. A better understanding of the conditions that prevailed at the onset and during the early phase of the epidemic will require further entomological investigations. Nevertheless, it appears probable that initial transmission as by sylvatic vectors such as the Ae. furcifer-taylori group and possibly others such as Ae. luteocephalus, Ae. metallicus, and Ae. vittatus. As the outbreak progressed, interhuman transmission by Ae. aegypti also occurred, and this mixed epidemiological pattern later gave way to transmission by Ae. aegypti only when sylvatic vector populations declined in the dry season. We speculate that a prolongation of the rainy season during 1976--1978 was important in the origin of the outbreak. The relationship of this epidemic to the established focus of sylvatic YF in southeastern Senegal is discussed. The Gambian outbreak is considered the result of a recent northwesterly extension of the YF Emergence Zone.
In a serological and entomological survey on yellow fever carried out in Sierra-Leone in 1972, altogether 899 sera from children 0 to 14 years were tested with 12 antigens by haemagglutination-inhibition and complement fixation tests. Mouse neutralization test with yellow fever, West-Nile and Zika viruses were also performed on selected sera. Generally speaking, the incidence of arboviruses is low but the prevalence of antibodies for some viruses was found to vary considerably between different areas. As regards yellow fever, the virus has recently been in circulation in only two areas: Bafodia and Lalehun-Labour Camp and there is no risk for a yellow fever outbreak to occur in the near future. Due to the shortness of the survey, entomological prospections were confined to a search for Ae. aegypti larvae in and around dwellings: no breeding places are found in houses and Breteau indices are usually low, especially in forest villages. On the other hand, in urban settlements in the mining areas, breeding places around houses are numerous and are bound to increase in number. All the conditions necessary for the outbreak of an epidemic would be present within few years: such a situation would appear in Labour Camp where yellow fever virus has been circulating, where most of the population has no immunity and where Breteau indice goes as high as 34.4. As regards the other arboviruses, Zika virus is active in most areas and Chikungunya virus is particularly active in the plateau and savanna zones, in the North-East.
The preliminary results of an entomological survey of the potential arbovirus vectors in the French Territory of Afars and Issas are exposed. 25 culicid species were recorded, specially Anopheles gambiae, Culex tritaeniorhynchus, C. univittatus, C. pipiens fatigans, Aedes caspius, Ae. vittatus, Ae. arabiensis. Ae. aegypti larvae were collected on a dhow arriving in Djibouti. 5 species of ticks and 4 sandfly speices were also recorded. The epidemiological modalities of certain arboviroses in this territory are discussed, depending on these entomological data and the uniterrupted travelling of local populations.
A one year entomological survey was carried out to precise the malaria vectors and the malaria transmission in Yaounde, the Cameroon capital (800,000 inhabitants). The study was done in two districts not yet fully urbanized: Nkol Bikok and Nkol Bisson. The latter is located at the periphery and has a pool. Anopheles gambiae was the only human malaria vector. Its agressivity for man depended on the urbanization of the district. Annual man biting rate was 284 in Nkol Bikok and 1,813 in Nkol Bisson. The densities were maximum in May-June and in October-November, corresponding to the end of the short and long rainy seasons. The presence of A. gambiae was permanent except in August-September in Nkol Bikok. In Nkol Bisson the density was higher in the houses near the pool. The yearly inoculation rate (h) was 14 in Nkol Bikok and 30 in Nkol Bisson. The vectorial transmission was observed in may in Nkol Bikok and during four months (June, August, January, February) in Nkol Bisson. These entomological data showed clearly that malaria transmission actually occurred in Yaounde and that the probability to receive at least one infected anopheline bite per year was very near to 1 for inhabitants unprotected against mosquito bites.
Following the establishment of the Environmental Protection Administration in 1987 and the occurrence of the dengue epidemic in 1988, resurgent interest and need have been created to promote and support medical entomology in Taiwan. Steps should be taken to strengthen the training of workers in medical entomology, to establish a society for vector ecology and control, to issue periodicals in English, and to coordinate with foreign institution. Items for applied research on vector and best control are suggested.
A circular representation of the twelve different forms of animal life is used to draw the reader's attention to the range of agent, vector, and victim of infectious diseases within the animal kingdom including man. This clearly reveals that particularly insects from the group of arthropods are playing a dominant role as vectors of pathogens. In connection with the metamorphosis of insects and the change of the habitat of their stages of development it is explained that within one and the same insect species, damage and benefit may be close to one another because their morphological types are of absolutely contrary hygienic importance: larval stages of disease transmitting imagines may perform important functions within the metabolic economy of nature. The present risk originating from insects in regions of the world that are free from epidemic diseases is due to a misinterpretation or neglecting of the variety of their functions. It is the objective of entomological research to overcome the partial character of assessing insects by the criteria of damage or benefit produced by them. The tasks of entomology within hygiene should be tackled in this field.
An arbovirus surveillance was carried out in Burkina Faso from 1983 to 1986. It was based on crepuscular catches of mosquitoes on human bait in some wooded areas and in one town. The total collection was 228 catches with an average of 8 men per catch. The total number of mosquitoes caught was 44,956 among which 32,010 potential vector of yellow fever; all these mosquitoes were analysed for arbovirology. In the south-western part of the country (region of Bobo-Dioulasso), surveillance was conducted each year from August to November, whilst the circulation of Aedes-borne arboviruses is well known to be favoured. In 1983, 1984 and 1986, seven strains of yellow fever virus were isolated in circumstances remarkably similar. They came from selvatic areas and never from the town. They concerned only Aedes (Stegomyia) luteocephalus which is the very predominant potential vector of yellow fever in the region. They were obtained in low figure, between 1 and 4 per year. They occurred from 27th of October to 21th of November. These observations confirm that the southern portion of the Sudan savanna zone of West Africa is the setting of a customary circulation of yellow fever virus and therefore belongs to the endemic emergence zone. In 1986, two strains of dengue 2 virus were isolated. One concerned Ae. luteocephalus from the selvatic area, the other Ae. (St.) aegypti from the heart of town. These data suggest two distinct cycles for dengue 2 virus, one urban and one selvatic, which could coexist simultaneously in the same region. In the south-eastern part of the country (region of Fada-N'Gourma) a yellow fever epidemic occurred between September and December 1983; its study has enable to precise their entomological aspects. The entomological inoculation rate of yellow fever virus has been evaluated to 22 infected bites per man during the month of october, for a man living close to forest gallery. 25 strains of yellow fever virus strains was isolated from Ae. (Diceromyia) furcifer which is the potential vector the most abundant in this region: the main role of this species in an epidemic was confirmed. An investigation in September 1984 had not permitted isolation of the virus therefore it is suspected that the large epizootic circulation of virus in 1983 has not been renewed the year after. In total 59 viral strains belonging to 10 different viruses were isolated from 9 species of mosquitoes.(ABSTRACT TRUNCATED AT 400 WORDS)
Three instances of the use of entomological techniques for the estimation of postmortem interval in homicide cases on the island of Oahu, Hawaiian Islands, are presented. These cases represent differing stages of decomposition and range from 8 to 53 days postmortem.
Sera from 30 workers in an entomological research institute and from five Sydney asthmatics, all with serum IgE antibodies to sheep blowfly (Lucilia cuprina) antigens, were studied with the aim of identifying individual IgE-binding proteins in extracts of L. cuprina adult flies, larvae and eggs, and in extracts of related species of flies from the order Diptera. Using protein blotting, 21, 18 and nine different IgE-binding components were identified in extracts of L. cuprina adult flies, larvae and eggs, respectively. A component(s) of MW 67 kD found in all three developmental stages, showed the highest frequency of IgE-binding; reacting, for example, with 70% of the sera tested with the adult fly extract. Some components were detected in only one of the three developmental stages. Investigations of possible allergenic cross-reactivity between L. cuprina and extracts from six other related species of flies revealed IgE-binding bands in each of the extracts as well as in an extract of Agrotis infusa, a cutworm not belonging to the order Diptera. One strongly reacting component of MW 20 kD was detected in extracts of five different fly species as well as in the A. infusa extract. The results suggested that allergenic cross-reactivity between some fly species exists, and may extend to taxonomically unrelated insect species.
Review of the most important contributions of the-25-year-old Department of Medical Parasitology and of the ten-year-old Reference Laboratory for Medical Arachno-Entomology at the Sanitary Inspection and Institute, District of Leipzig, as an example for the performance of hygienic zoology in the German Democratic Republic.