Jungle yellow fever: clinical and laboratorial studies emphasizing viremia on a human case

Os autores estudaram um caso humano de febre amarela silvestre, sob os aspectos clinico, laboratorial e epidemiologico. O paciente apresentava febre (39ºC), calafrios, sudorese, cefaleia, dor lombar, mialgia, dor abdominal em epigastrico, nauseas, vomitos, diarreia e prostracao. Realatava permanencia em areas onde foram constatados casos de febre amarela silvestre e nao havia historico de vacinacao anterior...

Presença de Aedes (stegomyia) albopictus (Skuse) na cidade de Säo Paulo-SP, Brasil / Prevalence of Aedes (Stigomyia) albopictus (Skuse) in the city of Säo Paulo, SP, Brazil

Através de coletas mensais realizadas pela Faculdade de Saúde Pública da USP foram encontradas larvas e um exemplar adulto de Aedes albopictus

Determinants and predictors of dengue infection in Mexico.

A national serosurvey was conducted in Mexico from March to October 1986 to identify predictors of dengue transmission and target areas at high risk of severe annual epidemics. A total of 3,408 households in 70 localities with populations less than 50,000 were randomly sampled, and serology was obtained from one subject under age 25 years in each household. When comparing exposure and infection frequencies across the 70 communities, the authors found that median temperature during the rainy season was the strongest predictor of dengue infection, with an adjusted fourfold risk in the comparison of 30 degrees C with 17 degrees C. High temperatures increase vector efficiency by reducing the period of viral replication in mosquitoes. The proportion of houses in a community with larva on the premises was significantly associated with the community proportion infected (odds ratio (OR)adj = 1.9; 95% confidence interval (CI) 1.4-2.5), as was the proportion of households with uncovered water containers present (ORadj = 1.9; 95% CI 1.4-2.7). Because these factors have effects beyond the individual household and subjects infected from them create a risk for other subjects, both analyses of effects and organization of control efforts must be at the community level. A predictive model was constructed using the community level risk factors to classify communities as being at high, medium, or low risk of experiencing an epidemic; 57% of these communities were correctly classified using this model.

Collection and separation of Aedes taeniorhynchus eggshells from mangrove soil.

Two methods to separate eggshells of Aedes taeniorhynchus from mangrove soil were compared. Selective sieving, using nested sieves with 0.185 and 0.170-mm screen openings, and water flotation both removed over 99% of the soil. However, water flotation recovered a significantly greater percentage of eggshells (62% vs. 34%). There was no significant difference in the recovery rate of viable eggs and new and old eggshells using water flotation.

[Mosquitoes (Diptera, Culicidae) found in the coastal region from Wejherowo to Darlowo]. / Komary (Diptera, Culicidae) znalezione w pasie przymorskim od Wejherowa do Darlowa.

Species composition Anophelini were investigated in the years 1986/87 and Culicini in 1987/88 at the part of the coastal region. The mosquitoes were caught from April till October, every week, at 47 stations (water reservoirs, free nature and cattle-sheds). Total 16,194 mosquitoes (2452 Anophelini and 13,742 Culicini) were caught. They belong to 26 species of 5 genera: Anopheles (4 spp.), Aedes (15 spp.), Coquillettidia (1 sp.), Culex (1 sp.) and Culiseta (5 spp.). The highest numbers of Anophelini were observed in July (1986) and in September (1987). The aggressiveness toward man showed by Culicini was found to be highest in the second half of May and at the end of July.

Culiseta minnesotae and further notes on Aedes aegypti in Rhode Island.

Culiseta minnesotae is reported as a state record in Rhode Island. Follow-up surveys for Aedes aegypti after its initial isolation in 1985 have failed to recover additional specimens.

Is Aedes albopictus in Australia?

In Brisbane during October 1988 one larva of the exotic dengue vector Aedes albopictus (Skuse) was collected by quarantine officers from a consignment of used vehicle tyres imported from Asia. Although this is not the first report of this mosquito in Australia, the finding was of sufficient importance to change quarantine procedures. Subsequently in Darwin during June 1989, two Ae. albopictus larvae were recovered from an ovitrap located near the wharves. This article reviews the global expansion of this species and, on the basis of previous imports of tyres into Australia, suggests that Ae. albopictus may already be established in this country.

Epizootiology of Amblyospora connecticus (Microsporida) in field populations of the saltmarsh mosquito, Aedes cantator, and the cyclopoid copepod, Acanthocyclops vernalis.

The natural ecology of a heterosporous microsporidium, Amblyospora connecticus was investigated at three different salt marsh habitats during 1986-1989. The parasite has a well-defined seasonal transmission cycle that occurs regularly each year and intimately involves the primary mosquito host, Aedes cantator, and the intermediate copepod host, Acanthocyclops vernalis. In the spring, the microsporidium is horizontally transmitted from the copepod, where it appears to overwinter, to the mosquito via the ingestion of haploid spores produced in the copepod. Mosquitoes develop a benign infection, and females transmit the microsporidium transovarially to their progeny via infected eggs. Oviposition occurs during the summer and infected eggs hatch synchronously in the fall causing widespread epizootics. Infected larvae die, and the cycle is completed when meiospores are released into the pool and subsequently are eaten by A. vernalis, which reappears in the fall and early winter. Amblyospora connecticus thereby persists by surviving in one of two living hosts throughout most of its life cycle rather than in the extra-corporeal environment. This represents an important survival strategy for A. connecticus as results show the salt marsh habitat to be a relatively unstable environment that is subject to periodic flooding and drying. The adaptive significance of utilizing an intermediate host in the life cycle is discussed as it directly facilitates transmission and enhances survival of the microsporidium.

Epidemiology and control of dengue virus infections in Thai villages in 1987.

A severe epidemic of dengue hemorrhagic fever (DHF) in Nakhon Ratchasima, Thailand in August of 1987 prompted a field investigation. DHF rates of 0.4-6.5 cases per 1,000 residents in subdistricts and 2-15 cases per 1,000 residents in 10 villages investigated were reported. Epidemics peaked in neighboring villages at different times; in June and July, and in August before the rainy season began late in the month. In 4 primary schools representing 6 villages, sera from groups of randomly selected children were tested for dengue IgM with the antibody capture ELISA test. Rates of recent dengue infection were 10-65% in the schools and correlated closely with reported rates of DHF. In an effort to control vectors, malathion fog and temephos (1% abate sand granules) were applied. Villagers were educated in prevention and were urged to cover water receptacles. The percentage of houses with larvae dropped from 67 to 20, the percentage of containers with larvae decreased from 30 to 5, and the number of containers with larvae per 100 households decreased from 221 to 33. This was a serious epidemic in which conventional control measures were only moderately effective.

Epidemic yellow fever in eastern Nigeria, 1986.

An epidemic of yellow fever occurred in the eastern part of Nigeria during the second half of 1986. Oju, in Benue State, was the most heavily affected region, but yellow fever also occurred in surrounding areas, particularly Ogoja, in Cross River State. In Oju, the mean attack and mortality rates were 4.9% and 2.8%, respectively. Sex and age specific rates were highest in males and in the 20-29 yr age group. The overall case fatality rate was approximately 50%. Diagnosis was confirmed by IgM capture enzyme-linked immunosorbent assay (ELISA) and complement fixation (CF) tests. Entomological investigations implicated Aedes africanus as the epidemic vector. Oju alone probably had about 9800 cases of yellow fever with jaundice, and some 5600 deaths. Outbreaks of this nature could be prevented by inclusion of yellow fever in the Expanded Programme on Immunisation, in areas subject to recurrent epidemics.

Research on parasitic arthropods of the Lake Zarnowieckie environs carried out in 1981-1985. Part II. Mosquitoes (Diptera, Culicidae).

In the years 1981-1985 a total of 19,651 specimens mosquitoes were collected in the area of investigation--Lake Zarnowieckie environs. In that amount 15,072 specimens were identified. There were found 26 species belonging to 4 genera: Anopheles, Aedes, Culex and Culiseta. Some of the species found, such as Aedes cantans, Aedes punctor or Culex pipiens are troublesome pests and particularly aggressive to man, possible vectors of many diseases. In the cowsheds there were found 12 species, the most numerous were the specimens of Anopheles genera (92.1% of the collection). The species captured in the open area by means of the man bait were 17 in number. The highest aggressiveness to man was shown by Ae. punctor, Ae. cinereus, Ae. cantans and Ae. annulipes. In the water bodies among the preimaginal forms caught there identified were 22 species. The majority of them were: Culex pipiens and Aedes punctor. A seasonal activity of the Culicidae preimaginal forms was also observed. The considerable environmental changes caused by the construction of the nuclear power plant, and the work of the pump-storage power plant are, as it seems, the main cause of the changes in the species domination observed in this region. Any finau conclusions, however, can be drawn after the further investigations are completed.

Evaluation of some adhesives for collecting Musca domestica and Chrysomya megacephala adults or mosquito larvae in sticky traps.

1. Seven types of water-insoluble adhesives were evaluated in sticky traps for collecting adults of Musca domestica L. and Chrysomya megacephala (Fabricius) or mosquito larvae (Aedes aegypti (L.) and Culex quinquefasciatus Say). 2. Adhesive viscosity affected the tackiness of the glues and this determined their trapping efficiency in air or water. 3. From the 'Hyvis' range of adhesives tested, 'Hyvis 200' was most effective for trapping adult flies. 4. With 24 h exposure to fourth instar Ae.aegypti larvae in tapwater, submerged plates coated with 'Hyvis 10', 'Hyvis 30' or 'Hyvis 200' formulations trapped the majority of larvae. In polluted water the highest rates of trapping were 17.3% of Ae.aegypti and 18.7% of Cx quinquefasciatus with 'Hyvis 200'. Floating traps were consistently less productive than submerged traps under laboratory conditions. 5. In a heavily polluted natural breeding-site of Cx quinquefasciatus, floating traps were more productive than submerged sticky traps with four of seven adhesives tested, the most efficient being 'Hyvis 200' (4.2 mosquitoes per hour) and Hyvis:polyethylene 90:10 (4.5/h). Despite the relative inefficiency of aquatic traps, emergent adults, pupae and second to fourth instars of larvae were collected quickly from the habitat.

Foco permanente de fiebre amarilla en el Valle del Río Apurímac, Ayacucho, Perú, y primer aislamiento del virus de la fiebre amarilla en ese país / A continuing focus of yellow fever in the Apurimac River Valley, Ayacucho, Peru, and the first isolation of yellow fever virus in that country

En 1977 ocurrió en el sur de Perú un extenso brote de una enfermedad hemorrágica que correspondía a la fiebre amarilla, y a pesar de uma amplia campaña de vacunación hubieron brotes recurrentes en años posteriores. Las circunstacias epidemiológicas en que acaecieron estos brotes indican que un importante factor determinante fue el ingreso, repetido anualmente, de trabajadores migratorios susceptibles en un foco enzootico de esta enfermedad. Durante el estudio de dichos brotes los autores intentaron aislar el virus de la fiebre amarilla de muestras de sangre obtenidas de seis pacientes en 1977, cuatro en 1978 y cuatro en 1981, en la zona endémica. Con este propósito se inyectó sangre entera de los pacientes a ratones lactantes (por via intracraneal), y se inocularon ademas cultivos de celulas C6/36 (Aedes albopictus), ratones lactantes, LLCMK2 y Vero. Las cepas del virus aisladas de seis de estos pacientes se identificaron posteriormente como agentes causales de la fiebre amarilla, y es esta la primera vez que se logra aislar el virus en Perú

[On an outbreak caused by dengue type 4 virus, in Thio, New Caledonia. Epidemiological and clinical aspects (author's transl)]. / Sur une épidémie de dengue de type 4 à thio, Nouvelle-Calédonie. Aspects épidémiologiques et cliniques.

After imported cases, a dengue outbreak, caused by type 4 virus, affected 11 per cent of the habitants of Thio, New Caledonia. Distribution of cases by sex, by ethnic and age group, by locality and by week is established on cases confirmed by serology and/or by virus isolation. Clinical aspect was classical but liver and digestive tract of patients were frequently affected. Five haemorrhagic forms were observed. Aedes aegypti was found in each visited house; pooled specimens were found infected by type 4 virus.

Prevalence of larvae of potential yellow fever vectors in domestic water containers in south-east Nigeria.

The seasonal variation in prevalence of Aedes (Stegomyia) mosquitos breeding in peridomestic water containers was assessed in an urban quarter of Enugu, Nigeria, and in two rural villages located among forest relicts in the neighbouring Udi Hills. A large number of earthenware pots, most of which contained water in the wet season, were present in the compounds around houses. Monthly determinations of the presence or absence of Aedes larvae in these containers were made for 13 consecutive months. The average Breteau index (positive containers per 100 houses) for A. aegypti during the 7-month wet season was 53 in one of the villages and 76 in the other, suggesting a high risk of yellow fever transmission; the dry-season averages were 11 and 23. In the urban quarter the wet-season average was 29; the dry-season average was 4.7, a level at which transmission is unlikely to occur. A. luteocephalus were occasionally found in containers in both the urban and rural localities, and A. africanus larvae occurred in one of the villages. Although Culex larvae were common, mixed infestations of Aedes and Culex were so uncommon that the simplified "single larva" method of sampling for Aedes gave similar results to the conventional method. The multiplicity of peridomestic containers in this part of Nigeria made the container index inadequate as a measure of larval density.