First Record of Culex (Microculex) daumastocampa (Diptera: Culicidae) in Mexico, with Notes on Cx. rejector and Cx. imitator.

Culex (Microculex) daumastocampa Dyar & Knab was originally described by Dyar and Knab (Proc US Nat Mus 35:53-70, 1908) from larvae collected at axils of bromeliads in Port San Felipe, Panama. Culex daumastocampa is found in Colombia, Venezuela, Panama, Suriname, Costa Rica, Nicaragua, Guatemala, and Mexico, although its presence had not been reported suggesting its northernmost distribution. In Mexico, the subgenus Microculex had included Cx. rejector Dyar and Knab, and Cx. imitator Theobald. However, after that collection specimens were re-examined along with other specimens collected during 2016 in Chiapas (all specimens are available in the Culicidae Collection of the Universidad Autonoma Agraria Antonio Narro Unidad Laguna [UAAAN-UL], Mexico). Culex daumastocampa is now reported for the first time in Mexico, Cx. rejector for Chiapas, and Cx. imitator removed from the checklist of previous reports as to be present in Mexico.

Preparation and structural characterization of vulcanized natural rubber nanocomposites containing nickel-zinc ferrite nanopowders.

Single-phase polycrystalline mixed nickel-zinc ferrites belonging to Ni0.5Zn0.5Fe2O4 were prepared on a nanometric scale (mean crystallite size equal to 14.7 nm) by chemical synthesis named the modified poliol method. Ferrite nanopowder was then incorporated into a natural rubber matrix producing nanocomposites. The samples were investigated by means of infrared spectroscopy, X-ray diffraction, scanning electron microscopy and magnetic measurements. The obtained results suggest that the base concentration of nickel-zinc ferrite nanoparticles inside the polymer matrix volume greatly influences the magnetic properties of nanocomposites. A small quantity of nanoparticles, less than 10 phr, in the nanocomposite is sufficient to produce a small alteration in the semi-crystallinity of nanocomposites observed by X-ray diffraction analysis and it produces a flexible magnetic composite material with a saturation magnetization, a coercivity field and an initial magnetic permeability equal to 3.08 emu/g, 99.22 Oe and 9.42 x 10(-5) respectively.

Parasitism by the endoparasitoid, Cotesia flavipes induces cellular immunosuppression and enhances susceptibility of the sugar cane borer, Diatraea saccharalis to Bacillus thuringiensis.

Cotesia flavipes Cameron (Hymenoptera: Braconidae), is a gregarious larval endoparasitoid of the sugarcane borer, Diatraea saccharalis Fabricius (Lepidoptera: Crambidae). The aim of this research was to analyze cellular immunosuppression of D. saccharalis parasitized by C. flavipes in terms of encapsulation, melanization, and hemocyte nodule formation. The encapsulation assay was done 1 and 6 days after parasitoid oviposition. In addition, the susceptibility of parasitized and nonparasitzed larvae to Bacillus thuringiensis HD 73 strain was assessed. 3, 12, and 24 h after bead injection; the percentages of encapsulation were significantly higher in unparasitized larvae compared to larvae parasitized 1 and 6 days after oviposition. Interestingly, there was a significant reduction in numbers of beads encapsulated at 1 day after oviposition compared to 6 days, and unparasitized larvae. The percentage of melanized beads decreased significantly in parasitized larvae compared to control. There was a reduction in the number of nodules in parasitized larvae compared to unparasitized controls. Larvae that were injected with polyndavirus 24 h before beads were injected showed significantly reduced encapsulation responses relative to control larvae. The D. saccharalis parasitized by C. flavipes exhibited higher susceptibility to B. thuringiensis. These results suggest that parasitization induced host immunosuppression, and the immunosuppression factors could impair the defense capacity against microbial pathogens--causing an increase in pathogen susceptibility.

Biocontrol potential and polyphasic characterization of novel native Trichoderma strains against Macrophomina phaseolina isolated from sorghum and common bean.

Native strains of Trichoderma isolated from sorghum and common bean crop soils were investigated to assess their biocontrol potential over the phytopathogenic fungus Macrophomina phaseolina, isolated from diseased plants. The Trichoderma strains were characterized with a polyphasic approach, which combined the analysis of their morphological characteristics, enzymatic activity, macro- and microculture test results, rDNA restriction patterns (AFLP), ITS1-5.8S-ITS2 rDNA sequences, and protein profiles. The integration of these data sets can be used to select new isolates as biological control agents against native fungal phytopathogens. In general, we observed a positive correlation between the secretion of beta-1,3-glucanase and N-acetylhexosaminidase, and the biocontrol capacities of all the Trichoderma isolates. Strains with the best hyperparasitic behavior against M. phaseolina isolated from diseased bean and sorghum were Trichoderma sp. (TCBG-2) and Trichoderma koningiopsis (TCBG-8), respectively.

Evaluación de la actividad antimalárica de algunas plantas utilizadas en la medicina tradicional cubana / Evaluation of the antimalarial activity in some Cuban medicinal plants

The search for new treatments against malaria has a highpriority in the fight to bring this disease under control. The aim of this study was to assess the therapeutic potential of extracts of plants selected on the basis of ethnobotanical information collected from Cuban traditional medicine. Extracts from six plants (Bambusavulgaris, Parthenium hysterophorus, Melaleuca leucadendron, Indigofera suffruticosa, Artemisia absinthium, Simarouba glauca) were tested for their invitro effect against the F32/Tanzania strain ofPlasmodium falciparum. S. glauca, P. hysterophorus, M.leucadendron and A. absinthium exhibited minimum inhibitory concentrations (MIC) in the range from 3.1to 50 g/mL, while B. vulgaris and I. suffruticosa showed negative activity against this strain. The highest in vivo activities against Plasmodium berghei NK65 were shownby A. absinthium, with a 65.9% reduction in parasitemia at a dose of 500 mg/kg, M. leucadendron, with 50%reduction at 250 mg/kg, and S. glauca, with 43.2%reduction at 100 mg/kg. The less toxic extracts wereA. absinthium and M. leucadendron. These results demonstrate the antimalarial properties of some Cuban medicinal plants and pave the way to detailed researchon their active chemical constituents.

Estimation of survival and gonotrophic cycle length of Simulium metallicum sensu lato (Diptera: Simuliidae) in southern Mexico.

This study compares the use of a mark-recapture analysis and a time-series analysis to estimate the gonotrophic cycle length and survivorship of Simulium metallicum s.l. in southern Mexico. Daily collections were performed with human- and horse-baited traps at 3 sites in a coffee plantation. The mark-recapture and time series experiments on these collections conclusively yielded a gonotrophic cycle length estimate of 3 days. Horizontal estimates of daily survivorship ranged from 0.75 to 0.69 and these values were similar to that estimated vertically of 0.77. The survival to infective stage (9 days) ranged from 0.012 to 0.043, taking into account at least 12 days for development of 3rd-stage larvae of Onchocerca volvulus. Mark-recapture and time-series methods were found to be suitable for estimating the gonotrophic cycle length and daily survivorship of S. metallicum s.l. under field conditions in southern Mexico.

Comparison of serological and parasitological assessments of Onchocerca volvulus transmission after 7 years of mass ivermectin treatment in Mexico.

OBJECTIVE AND METHOD: To compare the utility of an ELISA using 3 recombinant antigens with that of the skin biopsy to estimate incidence of infections in a sentinel cohort of individuals living in an endemic community in southern Mexico during a set of 11 subsequent ivermectin treatments. RESULTS: The apparent community prevalence of infection and microfilarial skin infection before and after 11 treatments with ivermectin plus nodulectomy were 78% and 13%, and 0.68 mf/mg and 0.04 mf/mg, respectively, as measured by skin biopsy. Of a group of 286 individuals participating in all surveys, a sentinel cohort of 42 mf and serologically negative individuals had been followed since 1994. The annual percentage of individuals becoming positive in this cohort was 24% (10/42), 28% (9/33), 0%, and 4.3% (1/23) in 1995, 1996, 1997 and 1998, respectively. Likewise, the incidence in children 5 years and under (n = 13) within this sentinel cohort was 15% (2/13), 18% (2/11), 0% and 11% (1/9), respectively. All individuals became positive to both tests simultaneously, indicating that seroconversion assessed infection incidence as accurately as skin biopsy in the sentinel group. CONCLUSION: Incidence monitoring of a sentinel cohort provides an estimation of the parasite transmission in the community; it is less costly than massive sampling, and a finger prick blood test might be more acceptable in some communities.

Detection of Onchocerca volvulus infection in Simulium ochraceum sensu lato: comparison of a PCR assay and fly dissection in a Mexican hypoendemic community.

Detection of Onchocerca volvulus larvae in vector populations is of prime importance in the assessment of the effectiveness of onchocerciasis control programmes. Traditionally, detection of larvae is attained by the dissection of flies, but this time-consuming method cannot easily discriminate between species of Onchocerca. The genome of all Onchocerca species has a unique 150 bp repeat, which can be amplified by PCR, and O. volvulus-specific DNA probes can detect these products by Southern blot (SB). This study optimizes a PCR/SB assay, and compares it with fly dissection to estimate the prevalence (p) and intensity of infection (m) in the local vector population of a Mexican community that has become hypoendemic as a result of 7 years of treatment with ivermectin and nodulectomy. The PCR detected 1 infected fly in a pool of 99 uninfected flies, but the optimal pool size was 50 flies. At the community level, 1 out of 10,550 flies was positive (p = 0.0095%, 95% confidence intervals CI = 0.00024-0.05280%; m = 0.00027 larvae/parous fly, CI = -0.00026-0.00081) by PCR, and 4 out of 10,772 flies (p = 0.0371%, CI = 0.01012-0.09505%; m = 0.00107 larvae/parous fly, 95% CI = 0.00002-0.00212) by dissection (observed m = 0.0005). Both methods produce statistically similar estimates of the prevalence and intensity, indicating that pool screening is a viable alternative for entomological surveillance in areas where the intensity of transmission is becoming extremely low as a result of control interventions.

Determination of sample sizes for the estimation of Onchocerca volvulus (Filarioidea: Onchocercidae) infection rates in biting populations of Simulium ochraceum s.l. (Diptera: Simuliidae) and its application to ivermectin control programs.

Monthly samples of biting Simulium ochraceum s.l. Walker were collected before and after ivermectin treatment in southern Mexico and analyzed for Onchocerca volvulus Leuckart infection rates, infection intensity, and the characteristics of larval distribution among parous flies. The variance over mean ratio (VMR) indicated that in all cases this distribution departed from Poisson and was strongly aggregated (VMR > 1). The negative binomial was found to be an adequate model with a small value of the aggregation parameter k, but the degree of larval overdispersion increased as the mean larval load decreased, invalidating the use of a common kc value. A linear relationship between k and the mean (mu) was established, k(mu) = k1 mu, which permitted exploration of the relationship between the observed proportion of infected flies, p, and the estimated mean larval burden per fly, m (all larval stages in parous flies). This would allow mean numbers of larvae per parous fly to be predicted from presence-absence data (e.g., from infection rates provided by polymerase chain reaction methods applied to pools of flies), assuming that k1 is a known parameter. Given that both p and m are naturally low in S. ochraceum, their relationship was practically linear within the range of observed values. Predictions were tested with the Mexican data from which the clumping parameter was estimated as well as for Guatemalan data for which this information was not available. Results showed a highly satisfactory degree of agreement between predictions and observations. The sample sizes required to estimate mean larval loads from prevalence data for fixed levels of precision (defined as the ratio between SE[m] and m) were calculated for realistic S. ochraceum infection rates (those found in published pre- and postcontrol field surveys as well as in this work). For the special case in which the relationship between k and the mean is linear and goes through the origin, k(mu) = k1 mu, the number of flies to be examined for O. volvulus infections does not explicitly depend on the aggregation parameter, but rather on the unknown proportion of infected flies. Practical recommendations for the calculation of sample sizes are discussed. For infection levels < 0.2%, a minimum number between 6,000 and 13,000 parous flies would have to be examined to estimate the mean larval load with a precision between 0.20 and 0.30. The linearity between onchocercal infection rate and infection intensity in the fly population indicates that relationships between the former and onchocerciasis patterns in the human population should be further explored for the purposes of monitoring the impact of ivermectin control programs through entomological evaluations.

[History of public health in Mexico: 19th and 20th centuries]. / Historia de la salud publica en México: siglos XIX y XX.

During the nineteenth and twentieth centuries, its growth accompanied the country's political and social changes. In the early half of the nineteenth century, care for the sick depended in part on religious charity. So-called public beneficial care was later introduced and consolidated under president Benito Juárez (1856) and then continued under Porfirio Díaz (1880-1910). The Mexican Revolution (1910-1917) brought the notion that public-health assistance is the State's social responsibility. Health care and social security are now both part of so-called "institutional medicine," which also encompasses research and teaching on public health. This analysis of public-health care in Mexico examines the question of diseases and their control, the emergence of institutions, and the development of the concept of public health.

Estimating the gonotrophic cycle and survivorship of Simulium ochraceum (Diptera: Simuliidae) during routine vector surveillance in southern Mexico.

The gonotrophic cycle, survivorship, and daily parity rate of Simulium ochraceum were estimated from specimens collected during routine vector surveillance in southern Mexico, using a vertical (time-specific) method. Series of sequential data analysis on parity of the entomological data obtained in February 1994 showed the highest significant (P < 0.05 alpha) correlation indices (r = 0.63 and r = 0.67) for a 4-day time lag, indicating that the mean gonotrophic cycle length corresponded to 4 days. Daily survival rate was estimated to be 0.80, the survival to infective age (12 days) to be 6.9%, and the daily parity rate to be 0.41. These estimations are in accordance with those previously obtained by others from mark-release-recapture experiments (horizontal method) in Guatemala.

Effect of semiannual treatments of ivermectin on the prevalence and intensity of Onchocerca volvulus skin infection, ocular lesions, and infectivity of Simulium ochraceum populations in southern Mexico.

The effect of semiannual ivermectin treatment along with nodulectomy on filarial transmission levels were estimated during the three dry seasons of 1991-1993 in a hyperendemic village in southern Mexico. Parasitologic and ophthalmologic examinations were carried out every six months until five drug treatments were completed. Ivermectin mass treatment with a coverage of approximately 80% had a significant impact (P < 0.05) on the prevalence of skin infection and the mean microfilarial skin density (CMFL), which were reduced 38% and 89%, respectively. A gradual and significant (P < 0.05) decrease in the mean microfilariae number in the anterior chamber of the eye and in corneal opacities was also observed as the CMFL was reduced. After three treatments, these were reduced 84% and 69%, respectively. However, after two years of continuous intervention, no significant differences (P > 0.05) were observed in either the daily mean infective biting density and the daily mean transmission potential. This was probably due to the remaining microfilarial load provided by the untreated resident population and migrant groups. On the whole, our results confirm both the efficacy of ivermectin to alleviate the clinical manifestations of the disease and its minimal impact on Onchocerca volvulus transmission, and indicate the need both to achieve higher levels of drug coverage and to incorporate other measures to stop transmission until a macrofilaricide drug is found.

Trophic status, oogenic stages, and insemination of resting populations of three Simulium species (Diptera: Simuliidae) in Chiapas, Mexico.

Of 176 black fly females collected resting at the edge of El Rosario River, 77% were caught in rocky shelters, whereas the others were captured on damp stretches of river bank. Simulium ochraceum predominated in the catches (74%), followed by Simulium metallicum (21%), and Simulium callidum (5%). Percentages of females without blood in their gut were 70, 85, and 67%, respectively. Of 55 S. ochraceum females that had recently oviposited (sacculate), 29 had the remains of a blood meal in the gut. Of 64 nulliparous females, 48 exhibited early oogenesis (Christopher's stage I-II) indicating recent emergence. At Las Golondrinas village, 36% (71) of 199 specimens were S. ochraceum, of these 85% had no blood in the midgut. Five females of S. ochraceum at this locality had red blood and 6 had black blood in their gut. Of 43 parous and 28 nulliparous females, 36 and 25 had ovaries at stages I-II, respectively. Most females of S. metallicum had no blood in their gut (92%). Nullipars were abundant (91) and stage N (24 h old) was observed in 66 of them.

[The effect of ivermectin on the transmission of Onchocerca volvulus in southern Mexico]. / Efecto de la ivermectina sobre la transmisión de Onchocerca volvulus en el sur de México.

We assessed the transmission potential and the mean infected and infective biting density of S. ochraceum in an onchocerciasis endemic community in the southern Mexican state of Chiapas. In addition, the impact of first treatment of ivermectin during the peak of natural infection of host-seeking S. ochraceum populations was also evaluated. Monthly entomological sampling was carried out during the year before treatment to assess the seasonal biting behavior of parous host-seeking S. ochraceum females, and either infected (with whatever stage of O. volvulus) or infective females (with only third larval stage of O. volvulus). The mean of infective biting density was unimodal with the peak in February. Higher densities of infective females were detected from January to March. Annual infective biting density estimated was 95.2 and the annual transmission potential of 152.3. After treatment with ivermectin, entomological collections were carried out during the December-April period. In these months, the first ivermectin mass treatment produced a reduction of natural infection rates of 55 per cent in the mean infected females density (p < 0.001) and of 30 per cent in the transmission potential. However, significative differences were found in parity rates of biting females during the evaluation periods. Decrease of infection rates in vector populations was caused by immediate effect of ivermectin over the skin microfilariae. Microfilariae community load available for transmission declined significantly from 14 Dmg/mg to 5.9 Dmf/mg. These means were statistically different (p < 0.001) and were reduced by 58 per cent from the baseline value.

[HLA DR7 as a protective factor against gold salt toxicity in rheumatoid arthritis]. / HLA DR7 como factor de protección frente a la toxicidad por sales de oro en la artritis reumatoide.

We performed a study of antigens HLA type I and II (specificity DR) in 90 patients with diagnosis of Rheumatoid Arthritis (RA) treated with Sodium Aurothiomalate (SATM) in order to detect the presence of an antigen HLA which could act as a protective factor against toxicity by SATM. Our results demonstrated a decrease in the frequency of the antigen DR7 in patients with toxicity by SATM, which suggests a protective factor of this antigen against the development of toxic reactions due to gold salts.

[Problems in the investigation of the control of Onchocerca volvulus in Mexico]. / Algunos problemas en la investigación para el control de la transmisión de Onchocerca volvulus en México.

The treatment and control of onchocerciasis in Mexico has been supported only on the administration of diethylcarbamazine and the removal of adult worms, which are in the onchocercomata. These actions seems to have diminished the prevalence and incidence of blindness in those individuals who are affected by this parasitosis. However, there has not been an important impact on onchocerciasis transmission. The objective of this paper is to critically analyze and discuss subjects related to diagnosis, treatment and control of onchocerciasis transmission in Mexico. Chemical vector control has been successfully achieved in other world regions; however, in Mexico, it has not been fully accepted as part of the integral onchocerciasis control due to several causes. Moreover, there has been few scientific research activities toward the search of new options for vector control. Recently, results of research on ivermectin (a microfilaricide agent) have indicated that this drug is effective and safe for the treatment of onchocerciasis. Additionally, it has been reported that ivermectin has an effect on the onchocerciasis transmission. However, there are several unanswered questions about the efficacy of ivermectin in stopping onchocerciasis transmission. In this report, the main efforts carried out in Mexico against onchocerciasis are analysed and problems related with diagnosis, treatment and control are also discussed. Some parameters for the correct evaluation of onchocerciasis control, with entomological emphasis, are proposed.

Observations on the flight and mating behavior of Anopheles pseudopunctipennis under insectary conditions.

Anopheles pseudopunctipennis showed a bimodal daily pattern in flight activity with the largest peak at 2000 h and the smaller one at 0400 h. In the first 10 days as adults, the maximum swarming activity was observed between 2-6 days of age. Also, sexual encounters were registered at the same time interval.