Prevalencia de infestación por Pediculus humanus capitis en escolares de despeñaderos (Provincia de Córdoba) / Prevalence of pediculus humanus capitis infestation in schoolchildren at Despeñaderos, Córdoba Province

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.

Daily pattern of flight activity of Aedes albifasciatus in Central Argentina

Aedes albifasciatus is an important common mosquito in Central Argentina. Its a confirmed vector of the Western Equine Encephalitis and is responsible for loss of milk production in dairy cattle during peak populations. This paper reports the flight activity pattern of Ae. albifasciatus for different seasons, in the southern coast of the Mar Chiquita Lake (Central Argentina). Data were collected by sampling two sites between 1992 and 1993 with CDC traps and human-bait captures. Adult mosquito population density, estimated by CDC trapping and human-bait, were highly correlated. However, when compared to other species, the proportion of Ae. albifasciatus was higher in human-bait collections. Adult female populations were active only when temperature were higher than 6§C. Two daily biting peaks were observed (dusk and dawn) during the spring, summer and autumn, and only one peak during winter (around 15:00 pm). Adult abundance was significantly correlated (R²= 0.71; p<0.01) with temperature and illumination.

The biology of Aedes (Ochlerotatus) albifasciatus Macquart, 1838 (Diptera: Culicidae) in Central Argentina

Aedes albifasciatus is a flood water mosquito ocurring in the southern countries of South America. It is a competent vector of the Western Equine Encephalitis (WEE) and causes important losses on milk and beef production in central Argentina. Field work was carried out from December 1990 to March 1993, on a monthly basis during the dry season and biweekly during the rainy season. Larvae were collected using the 'dipping' technique and females with CDC traps baited with CO2. Field collected larvae were used to build laboratory cohorts, from which basic population parameters were estimated. Eggs survived up to six months on dry soil, although there was a linear decrease of viability with time. At 23§C, larval development time was around nine days, and all adults emerged within one week. The estimation of larval development in the laboratory seems to be very near the development on the field, as larvae have been collected on average eight days after a rainfall. Egg to adult survival was 83 por cento, with the highest mortality on fourth larval instar (6 por cento). In the laboratory studies, sex proportion among the adults was 1:1, females lived longer than males (median 13 and five days, respectively), and adult survival pattern showed a constant number of individuals dying per unit time. Field collected females layed an average of 84 eggs per batch, and completing up to five gonotrophic cycles, suggesting an estimated survival of up to 35-50 days.