ABSTRACT
OBJETIVO: Estudiar la fluctuación estacional de Aedes aegypti y correlacionar su abundancia con factores ambientales. MÉTODOS: Las colectas fueron realizadas entre octubre de 2002 y noviembre de 2003, en la ciudad de Resistencia, província del Chaco, Argentina. Fueron hechos muestreos semanales empleando ovitrampas. El número de huevos colectados fue correlacionado con la temperatura, humedad relativa ambiente, evaporación y precipitaciones registradas en dicha localidad. Se utilizó el test de correlación de Pearson con los respectivos datos climáticos semanales, realizándose correlaciones simples y múltiples. RESULTADOS: La ocurrencia de huevos fue registrada de manera discontinua, desde la última semana de octubre de 2002, hasta la última de junio de 2003, a partir de la cual no fueron encontrados hasta noviembre de 2003. Se observó un pico de abundancia (70 por ciento) en noviembre y diciembre, que coincidió con el período de temperaturas altas y mayores precipitaciones. Otro pico, aunque de menor importancia, fue observado en abril y coincidió con las lluvias de otoño. Las correlaciones fueron significativas solamente para las precipitaciones acumuladas mensuales (r=0,57; P<0,05). No se registraron oviposturas en invierno cuando la temperatura media semanal fue inferior a 16,5ºC. CONCLUSIONES: Los resultados muestran correlación entre la oviposición y las precipitaciones, pues los períodos de mayor actividad de Aedes aegypti ocurrieron en el final de la primavera, comienzos del verano y en el inicio del otoño. Estos serían los períodos de mayor riesgo epidemiológico especialmente ante la aparición de personas infectadas.
Subject(s)
Aedes , Climate Change , Oviposition , SeasonsABSTRACT
Antecedentes. En 1995 Ingresó Aedes aegypti, vector de los Flavivirus Dengue y Fiebre Amarilla, al territorio provincial. En consecuencia, es necesario cuantificar la abundancia del vector para determinar la situación de riesgo y evaluar las acciones de prevención y control Implementadas. Objetivos. Determinar la abundancia del vector en nuestro medio, como así también la preferencia por los recipientes que puede utilizar como criaderos. Materiales y Métodos. En seis barrios de la ciudad de Córdoba se realizaron muestreos a fin de detectar criaderos de Ae. Aegypti, y determinar los índices de Vivienda, Recipiente y Breteau. Resultados. Se encontraron larvas y pupas de Ae. Aegypti en una gran variedad de recipientes, la mayoría de los cuales habían sido descartados. El índice de Vivienda estimado fue de 47%, mientras que el de Recipiente fue de 24%. El índice de Breteau calculado fue de 106%. Conclusiones. De acuerdo a los índices estimados, la ciudad de Córdoba se encuentra en una situación de riesgo ante la entrada de personas infectadas provenientes de zonas con dengue. En consecuencia resulta necesario intensificar las acciones, principalmente la educación sanitaria, la vigilancia y el control de Ae. Aegypti, como medidas para la prevención del dengue en la reglón.
Background: In 1995, Aedes aegypti, vector of the Flavivirus Dengue and Yellow Fever, reached the province. Therefore, it is necessary to quantify the vector abundance in order to determine the level of risk and to evaluate the prevention and control actions implemented. Objectives: To determine the vector abundance breeding place preferences. Materials and methods: Surveys of Ae. aegypti larva-pupa-infested containers were conducted in six neighborhoods of Cordoba city in order to determine the House, Container, and Breteau Indices. Results: Larvae and pupae of Ae. aegypti were found in a great variety of containers, most of which had been discarded. The House Index obtained was 47 %, while the percentage of water-holding containers examined that had larva or pupa was 24 %. The Breteau Index was estimated at 106 %. Conclusions: According to the indices estimated, Cordoba city is in a risk situation if any infected person with any dengue virus enters our city. Therefore, it is necessary to intensify the measures, mainly the sanitary education, vector surveillance and control, in order to prevent any form of dengue in the region.
Subject(s)
Animals , Aedes/physiology , Disease Reservoirs , Dengue/prevention & control , Insect Vectors/physiology , Argentina , Housing , Larva , Mosquito Control , Population Density , PupaABSTRACT
BACKGROUND: Approximately 80 per cent of Argentine children have pediculosis, making it imperious to detect the defects in the prevention and control actions for this parasitosis. OBJECTIVES: To study the infestation level by P. h. capitis, its temporal variation, and the association between infestation and host characteristics. MATERIALS AND METHODS: A monthly census in children of 6-8 years old from 2 primary schools (state and private) was carried out, recording the parasite stages found, children characteristics (sex, colour and length of hair), and infestation level. Data were analysed by means of contingency tables, difference of proportions, quotient of chances, and rank correlation coefficient. The independence of variables was analysed by c' test. RESULTS: The prevalence and chances of becoming infested were higher at the state school, where also all infestation levels were recorded, which did not occur at the private institute. The frequency of children infested was significantly lower when they had short hair. The correlation among infestation degree and hair length (short-long) was only significant for boys. Pediculosis cases were recorded at the beginning of the school year in both educative institutions, which demonstrated that infestation was acquired not only at school but also at home. CONCLUSIONS: Pediculosis is a social problems and the whole community must participate in preventive and control actions, for which sanitary education is essential, and the myth that the school is the only place of contagion must be eradicated.
Subject(s)
Humans , Male , Female , Child , Lice Infestations , Pediculus , Scalp Dermatoses , Argentina , Prevalence , Risk Factors , Scalp Dermatoses , Seasons , Severity of Illness Index , Socioeconomic FactorsABSTRACT
Allele frequencies at seven polymorphic loci controlling the synthesis of enzymes were analysed in six populations of Culex pipiens L. and Cx. quinquefasciatus Say. Sampling sites were situated along a north-south line of about 2,000 km in Argentina. The predominant alleles at Mdh, Gpdh and Gpi loci presented similar frequencies in all the samples. Frequencies at the Pgm locus were similar for populations pairs sharing the same geographic area. The loci Cat and Hk-1 presented significant geographic variation. The latter showed a marked latitudinal cline, with a frequency for allele b ranging from 0,99 in the northernmost point to 0.04 in the southernmost one, a pattern that may be explained by natural selection (Fst=0.46;p<0.0001) on heat sensitive alleles. The average value of Fst(0.088) and Nm (61.12) indicated a high gene flow between adjacent populations. A high correlation was found between genetic and geographic distance (r=0.83;p<0.001). The highest genetic identity (In=0.988) corresponded to the geographically closest samples from the central area. In one of these localities Cx. quinquefasciatus was predominant and hybrid individuals were detected, while in the other, almost all the specimens were identified as Cx. pipiens. To verify the fertility between Cx. pipiens and Cx. quinquefasciatus from the northern- and southernmost populations, experimental crosses were performed. Viable egg rafts were obtained from reciprocal crosses. Hatching ranged from 76.5 to 100 per cent. The hybrid progenies were fertile through two subsequent generations.
Subject(s)
Animals , Culex/genetics , Argentina , Crosses, GeneticABSTRACT
Culex (Culex) maxi Dyar is described in the adult, pupal and larval stages, and the male genitalia and parts of the fourth-instar larva are illustrated. The larva is described for the first time. The paper includes a summary of available information on the taxonomy, bionomics and distribution of the species. The taxonomy and identification of the species are reviewed in light of current knowledge of the subgenus Culex in the New World.
Subject(s)
Animals , Male , Female , Culex/physiology , Larva/physiology , Pupa/physiologyABSTRACT
Adult cohorts and immature stages were kept under field conditions during the autumn and winter of three consecutive years. Survival, oviposition and development time from egg to adult were considered. The adult cohorts were studied under three experimental conditions: unfed cohorts, cohorts fed with sugar solution and cohorts fed with both sugar solution and blood (chicken). Female longevity showed significant differences among the tree treatments. Females of unfed cohorts lived up to three weeks; females fed with sugar solution survived until six weeks, while those fed both with sugar and blood lived at most fourteen weeks; after the blood intake eggs were laid. In the immature stages, the highest relative mortality rates ocurred during the egg and larval stages. Total pre-adult mortality varied between 59.09 and 89.71 per cent. The development duration from egg to adult was between 43-62 days; there were no differences among results obtained for the three years.
Subject(s)
Animals , Culex/physiology , Behavior, Animal , SeasonsABSTRACT
Com o propósito de estudar a preferência de mosquitos fêmeas por hospedeiros vertebrados, realizaram-se amostragens quinzenais nas cidades de Córdoba e Cosquín (Argentina), durante o período de outubro a abril (primavera-veräo), por dois anos consecutivos. Utilizaram-se armadilhas com iscas animais: anfíbios, aves, mamíferos e répteis. Dos espécimes coletados, 92,9 porcento pertenciam ao gênero Culex, 7,0 porcento a Aedes e 0,02 porcento a Psorophora ciliata, única espécie coletada desse gênero. A maior proporçäo de fêmeas (68,7 porcento) foi captura em armadilhas iscadas com galinhas, seguindo-se em ordem as armadilhas com coelhos (29,9 porcento), com tartarugas (0,8 porcento) e com anfíbios (0,05 porcento). Assim, a maioria dos mosquitos foi coletada em armadilhas com hospedeiros homeotermos. Culex dolosus alimentou-se em todas as iscas, enquanto que Cx. acharistus, Cx. chidesteri, e Cx. quinquefasciatus em galinhas, coelhos e tartarugas; Ae. albifasciatus, Ae. scapularis, Cx. bidens e Cx. coronator fizeram-no em ambos hospedeiros homeotermos; Cx. apicinus, Cx. maxi, Cx. saltanensis e Cx. spinosus alimentaram-se apenas em galinhas e Ps. ciliata em coelhos