Neisseria meningitidis PorA variable regions: rapid detection of P1.7 and P1.19 variants by PCR.

AIM: Rapid characterization of variable region (VR)1 variants of the porA gene among invasive strains is crucial for outbreak management and epidemiology studies. Recent sequence analysis studies in Brazil showed that the VR1 P1.7 and P1.19 variants are highly prevalent, accounting for 68%, of the total number of VR1 variants characterized. The aim of this work is to develop a rapid polymerase chain reaction (PCR)-based method for genosubtyping Neisseria meningitidis by detection of porA variable regions P1.7 and P1.19. METHODS AND RESULTS: PCR primers for the detection of porA VR1 P1.7 and P1.19 were designed and tested using 198 clinical N. meningitidis isolates that had been previously evaluated by porA sequencing. All 50 strains with VR1 P1.7 and all 65 strains with VR1 P1.19 were positively identified by the respective VR-specific PCR and no false-positive reactions occurred. CONCLUSIONS: VR-specific PCR amplification accurately identified VR P1.7 and P1.19 strains. SIGNIFICANCE AND IMPACT OF THE STUDY: To overcome the disadvantages of serosubtyping and sequencing for typing the porA VR1 segment of N. meningitidis, we developed a PCR-based method to rapidly and accurately detect VR1 P1.7 and P1.19 variants. This approach is highly specific and sensitive; moreover it may allow for genotype determination of culture-negative samples.

[Search of natural occurrence of xiphidiocercariae (trematoda) in fresh water snails of nine countries from São Paulo State, Brazil]. / Búsqueda de xifidiocercarias (Trematoda) en moluscos de agua dulce recolectados en nueve municipios del Estado de São Paulo, Brasil.

Xiphidiocercariae, aquatic larval stages of some trematodes are considered a potential instrument for biological control of mosquitoes. In this study we evaluated its natural occurrence in Campinas region and two places in Vale do Ribeira (Registro and Miracatu), São Paulo State. Snails were obtained from fresh water collections from September 1996 to February 1999. The species collected were Lymnaea columella, Physa marmorata, Biomphalaria tenagophila, Biomphalaria sp., Drepanotrema cimex, D. lucidum and Drepanotrema sp. Fasciola hepatica, xiphidiocercariae (Haematoloechidae) and echinostomatid cercariae were detected in the lymnaeids snails from Miracatu, SP. In the same locality were found planorbids snails parasitized by furcocercariae, echinostomatid cercariae and xiphidiocercariae. The xiphidiocercariae found in the planorbids were different from those obtained from lymnaeids. One Biomphalaria sp. infected with furcocercariae was found in Louveira, SP. In the ROSA place (Campinas, SP) an individual of Biomphalaria sp. and one of L. columella were found infected by the furcocercariae and echinostomatid cercariae, respectively. In the place UNI-I, in Campinas, one L. columella was infected by furcocercariae. Double infection in snails from Miracatu was also observed.

Survey of cyclopids (Crustacea, Copepoda) in Brazil and preliminary screening of their potential as dengue vector predators.

INTRODUCTION: Cyclopid copepods are known to be good mosquito controllers, specially as regards the larvae of the dengue vectors Aedes aegypti and Ae. albopictus. MATERIAL AND METHOD: The objective of the study was to survey the local copepod fauna and search for new strains of M. longisetus var. longisetus, comparing the potential of the samples found with the current strain ML-01 against Ae. albopictus larvae, under laboratory conditions. Eleven bodies of water in Campinas, SP, Brazil, were screened for copepods by collecting 1.5 l of water from each of then. The predatory potential of adults copepods was evaluated over 24 h, in the laboratory, for groups of 5 individuals preying upon 30 first instar Ae. albopictus larvae. RESULTS AND CONCLUSION: The following cyclopid species were found: Metacyclops mendocinus, Tropocyclops prasinus, Eucyclops sp, Eucyclops serrulatus, Eucyclops solitarius, Eucyclops ensifer, Macrocyclops albidus var. albidus and Mesocyclops longisetus var. longisetus. The predatory potential of these copepods ranged from nil to 97.3%. A sample collected in the field containing only M. longisetus var. longisetus showed the best control efficiency with no significant difference from a three-year old laboratory culture (ML-01) of the same species evaluated for comparison. The sample with few M. albidus var. albidus was ranked in second place showing an average 25.9% efficiency. The use of copepods in trap tires as dengue vector controllers is discussed.

[Susceptibility of populations of Simulium (Chirostilbia) pertinax Kollar, 1832 (Culicomorpha, Simuliidae) to eemephos and to Bacillus thuringiensis var. israelensis-based formulation]. / Susceptibilidade de populações de Simulium (Chirostilbia) pertinax Kollar, 1832 (Culicomorpha, Simuliidae) ao temephos e a um formulado à base de Bacillus thuringiensis var. israelensis.

The use of wooden troughs on stream beds, artificially colonized by blackfly larvae, is proposed for larvicide evaluations. Mortality was recorded 3 or 4 hours after treatment. Larval susceptibility was also evaluated utilizing the LT50 criterion. In there field assays Simulium (C.) pertinax populations from the litoral of S. Paulo and Rio de Janeiro States were shown to be resistant to temephos, even when subjected to high concentrations. Vectobac 12 AS, a Bacillus thuringiensis var. israelensis product, was shown to be more potent against late instar larvae and efficient in concentrations higher than 7,200 ITU/l (10 min). The LT50 to 3,744 ITU/l (10 min) was calculated as 70.9 min.

[Evaluation of the sensitivity of adult Culex quinquefasciatus Say to chemical insecticides]. / Avaliação da sensibilidade de adultos de Culex quinquefasciatus Say a inseticidas químicos de contato.

The sensitivity of the adult house mosquito Culex quinquefasciatus to 5 chemical insecticides was evaluated under laboratory conditions, based on the Median Lethal Time (LT50) criterion. The organophosphorous Malathion and four pyrethroids: Bifenthrin, Deltamethrin, Esfenvalerate and Alfamethrin were utilized. An easy and efficient technique was suggested for the testing of one-day-old adults, including five repetitions for each treatment. The results revealed the full adequacy of this method for routine use. Further, no resistance to the 5 chemical compounds was detected among this natural population of Cx. quinquefasciatus.

Methods for field detection of resistance to temephos in simuliids. Larval esterase level and topical application of the insecticide to adults.

Two practical field methods for indirect detection of simuliid populations resistant to temephos are proposed. The first is based on high esterase activity in resistant larvae and involves adaptations of a filter paper test in which faintly stained spots indicate susceptible populations and strongly stained ones reveal populations resistant to temephos. The second is based on the resistance to the larvicide when adults are topically exposed, and involves the use of diagnostic doses obtained by the comparison between the LD50 for susceptible and resistant populations. The relevance of such methods is discussed in order to help resistance detection in Simulium pertinax Kollar control programmes.