Classical Control Measures Research Articles

Evaluation of Two SNP Markers in DPPA2 and SYTL3 Genes for Association with Host Response against Visna/Maedi Infection in Turkish Sheep

Visna/maedi (VM) is an incurable viral disease of sheep causing serious production losses across the globe. Classical control measures against VM such as screening and culling are costly and time-consuming. Breeding VM resistant sheep could provide an opportunity for struggling with the VM and decreasing the economic loss. In this study, we aimed to investigate possible associations between two previously reported single nucleotide polymorphisms (SNPs) in the ovine DPPA2 and SYTL3 genes and VM serostatus, and evaluate implementation of selective breeding strategies against VM in Karacabey merino, Kivircik, Imroz, and composite breeds; Bandirma, Hampshire crosses (HAMP), Ramlic and Black-headed German mutton crosses (SBA) which are reared in Marmara region of Turkey. For this purpose, we genotyped the sheep which VM serostatus were determined previously. The genotyping results showed that these SNPs in the DPPA2 and SYTL3 genes are polymorphic. We have conducted an association analysis with an experimental design using case-control matched pairs. Finally, a power analysis was performed to determine the power of the statistical analysis. According to our findings, within our detection limits (the minimum odds ratio 2.5 to 2.8; CI 95; statistical power 0.96; p-value < 0.05), there was no significant association between the SNPs in the DPPA2 and SYTL3 genes and VM serostatus. Therefore, these SNP markers are not useful to selective breeding against VM in Turkish sheep.

Containing the spread of coronavirus disease 2019 (COVID-19): Meteorological factors and control strategies

The novel coronavirus disease 2019 (COVID-19) has spread globally and the meteorological factors vary greatly across the world. Understanding the effect of meteorological factors and control strategies on COVID-19 transmission is critical to contain the epidemic. Using individual-level data in mainland China, Hong Kong, and Singapore, and the number of confirmed cases in other regions, we explore the effect of temperature, relative humidity, and control measures on the spread of COVID-19. We find that high temperature mitigates the transmission of the disease. High relative humidity promotes COVID-19 transmission when temperature is low, but tends to reduce transmission when temperature is high. Implementing classical control measures can dramatically slow the spread of the disease. However, due to the occurrence of pre-symptomatic infections, the effect of the measures to shorten treatment time is markedly reduced and the importance of contact quarantine and social distancing increases.

Measles epidemic in Brazil in the post-elimination period: Coordinated response and containment strategies

Purpose: The measles virus circulation was halted in Brazil in 2001 and the country has a routine vaccination coverage against measles, mumps and rubella higher than 95%. In Ceará, the last confirmed case was in 1999. This abstract describes the strategies adopted and the effectiveness of the surveillance and control measures implemented during the epidemic in an attempt to understand the challenges posed by the regional context of post-measles elimination and explain the actions taken to prevent the re-establishment of endemic transmission when the virus is imported. Methods & Materials: A descriptive study was conducted to examine immunization strategies, epidemiological and laboratory surveillance, and communication to contain and halt the chains of measles transmission during an epidemic between December 2013 and October 2015. Results: The epidemic started in December 2013 and lasted 20 months, reaching 38 cities and 1,052 confirmed cases. The D8 genotype was identified. More than 50,000 samples were tested for measles and 86.4% of the confirmed cases had a laboratory diagnosis. The beginning of an campaign vaccination was delayed in part by the availability of vaccine of vaccine. The classic control measures were not enough to control the epidemic. The creation of a committee of experts, the agreement signed between managers of the three spheres of government, the conducting of an institutional active search of suspected cases, vaccination door to door at alternative times, the use of micro planning, a broad advertising campaign at local media and technical operative support contributed to containing the epidemic. Conclusion: It is important to recognize the possibility of epidemics at this stage of post-elimination and prepare a sensitive surveillance system for timely response. The point in the epidemic when the number of cases began to decrease clearly coincided with the point at which the activities of epidemiological surveillance, the immunization sector, coordinated communication actions, laboratory surveillance and primary care were integrated. This coordinated response reduces the chances of spreading the virus and thus the harm and the impact of a measles epidemic

Results of a population screening intervention for tuberculosis in a Nunavik village, Quebec, 2015-2016.

A small village in Nunavik, Quebec experienced a tuberculosis (TB) outbreak in 2012-2013 and then a resurgence in 2015-2016. Cases were still occurring, despite the fact that contact tracing had already been conducted on one quarter of the population. A decision was taken to conduct large-scale screening of the population for TB. To describe the results of a population-based TB screening intervention designed to identify individuals with latent TB infection (LTBI) or active TB requiring treatment. The history of TB infection (either active TB or LTBI, defined as a positive tuberculin skin test result of at least five mm induration) and treatment (considered adequate if at least 80% of prescribed doses were taken) were determined. Those who were two years of age and older and had not been included in contact tracing after June 1, 2015 were included for TB screening (n=1,026 eligible individuals). Screening included a nurse assessment, tuberculin skin test (TST) for those with previous negative TST or of unknown status and chest X-ray for the others. Of the eligible individuals in the affected village, 1,004 (98%) participated in the screening. Of these, 30% had a history of previous TB infection. A TST screening was administered to 71% of the participants, 10% of whom had positive results. Assessments were performed on 425 participants and 385 underwent a chest X-ray. Fifty-two cases of previously diagnosed active TB and three cases of new active TB were documented. In addition, there were 247 individuals with LTBI who had been previously identified (191 were found to have had adequate LTBI treatment, 56 were found to have had inadequate LTBI treatment) and 69 were identified with de novo LTBI. In addition, 633 participants were found to have no TB infection. There were 125 participants who were referred for LTBI treatment. Follow-up information was available for 120 and 85 (71%) of these completed the treatment. Within this northern village, which had persistent TB transmission despite classic control measures, population-based screening had a high degree of coverage and was an effective way to detect additional cases of individuals with active TB and those with LTBI.

Measles epidemic in Brazil in the post-elimination period: Coordinated response and containment strategies

The measles virus circulation was halted in Brazil in 2001 and the country has a routine vaccination coverage against measles, mumps and rubella higher than 95%. In Ceará, the last confirmed case was in 1999. This article describes the strategies adopted and the effectiveness of surveillance and control measures implemented during a measles epidemic in the post-elimination period. The epidemic started in December 2013 and lasted 20 months, reaching 38 cities and 1,052 confirmed cases. The D8 genotype was identified. More than 50,000 samples were tested for measles and 86.4% of the confirmed cases had a laboratory diagnosis. The beginning of an campaign vaccination was delayed in part by the availability of vaccine. The classic control measures were not enough to control the epidemic. The creation of a committee of experts, the agreement signed between managers of the three spheres of government, the conducting of an institutional active search of suspected cases, vaccination door to door at alternative times, the use of micro planning, a broad advertising campaign at local media and technical operative support contributed to containing the epidemic. It is important to recognize the possibility of epidemics at this stage of post-elimination and prepare a sensitive surveillance system for timely response.

Single nucleotide polymorphisms in candidate genes and their relation with somatic cell scores in Argentinean dairy cattle.

The prevention and control of bovine mastitis by enhancing natural defenses in animals is important to improve the quality of dairy products. Mastitis resistance is a complex trait which depends on genetic components, as well as environmental and physiological factors. The limitations of classical control measures have led to the search for alternative approaches to minimize the use of antibiotics by selecting naturally resistant animals. Polymorphisms in genes associated with the innate immune system are strong candidates to be evaluated as genetic markers. In this work, we evaluated a set of single nucleotide polymorphisms (SNPs) in candidate genes for health and production traits, and determined their association with the somatic cell score (SCS) as an indicator of mastitis in Argentinean dairy cattle. We evaluated 941 cows: Holstein (n = 677) and Holstein × Jersey (n = 264) crossbred, daughters from 22 bulls from 14 dairy farms located in the central dairy area of Argentina. Two of the 21 successfully genotyped markers were found to be significantly associated (p < 0.05) with the SCS: GHR_140 and OPN_8514C-T. The heterozygote genotype for GHR_140 showed a favorable effect in reducing the SCS. On the other hand, heterozygote genotypes for OPN8514C-T caused an increase in the SCS; moreover, combined genotypes for OPN SNPs showed an even larger effect. These findings can contribute to the design of effective marker-assisted selection programs.

Measles Outbreak in Venezuela: A New Challenge to Postelimination Surveillance and Control?

The circulation of wild measles virus was interrupted in Venezuela in February 2007 after the catch-up vaccination (1994) and monitoring (1998) and in response to the measles outbreak in 2001. Traditionally, the routine coverage with measles-mumps-rubella vaccine does not exceed 85%. In February 2006, a measles outbreak started by importation in the State Miranda; this extended to 7 states and lasted 50 weeks with an intermediate period of 17 weeks without reported cases. New cases were reported in the States Guarico and Amazon. The pattern of circulation of the silent period was determined through the use of retrospective search for measles; this showed that 57% of suspected cases did not enter the surveillance system. Molecular epidemiology made it possible to identify B3 as only genotype, which also circulated in Spain. The epidemiological and clinical characteristics of measles have been modified; these determine outbreaks identified late, of slow expansion, silent, and with limited case-fatality, compared with classical outbreaks. The outbreak spread by that behavior was not recognized and the classical control measures did not result. The beginning of a broader and intense vaccination was delayed, partly by weaknesses in the sensitivity of the system. It is crucial to recognize the new behavior of measles and the effectiveness of the classical control measures, and especially to establish criteria for interruption of the circulation to control an outbreak in this stage of elimination.

Natural progression of Bovine Leukemia Virus infection in Argentinean dairy cattle

We describe the progression of Bovine Leukemia Virus (BLV) infection from birth until the first lactation in 61 animals from a typical large dairy herd of Argentina, with more than 85% of prevalence. The purpose was to identify potential points to effectively break the BLV cycle of transmission in our dairy productive system. We detected early infection in 11.47% of newborn calves by nested PCR. From birth to 12 months, no evidence of new infections was observed. After 12 months of age, the detection of new reactors increased slowly with time, from 15.09% at 15 months to 24% at 27 months. After that, the number of reactors increased rapidly up to 40% and 60.76% at 30 and 36 months, respectively. This last 9-month period coincided with parturition and the entry into the milking herd. Real-time PCR showed that more than 75% of adult animals had low peripheral-blood proviral load. Complementary, all infected animals showed low levels of provirus in milk and colostrum. The most important finding was that even when management procedures to prevent BLV iatrogenic transmission were followed, no significant change was observed in the prevalence after three years, strongly suggesting that other way/s of transmission play a key role under natural conditions. This study showed an interesting baseline to draw an alternative approach based on selective segregation according to the peripheral-blood proviral load as a potential indicator of risk transmission, and as an alternative to classical control measures.

Traditional and transgenic strategies for controlling tomato-infecting begomoviruses

Viruses of to the family Geminiviridae are considered some of the most important pathogens in tropical and subtropical regions of the world. Members of one Geminiviridae genus, Begomovirus, have been causing severe losses, particularly in tomato (Lycopersicon esculentum) production in the Americas and the Caribbean. Several new begomoviruses have been reported in the region and, at least one, Tomato yellow leaf curl virus (TYLCV), has been brought in from the Old World via infected transplants. In addition, the recombination events that are playing an important role in Begomovirus diversity have increased the complexity of their control. This scenario has led to the search for control measures that go beyond traditional host genetic resistance, chemical controls and cultural practices. In this review, besides the recommended classical control measures, transgenic approaches will be discussed, as well as the mechanisms involved in their successful control of viruses.

Clinical assay of N-duopropenide alcohol solution on hand application in newborn and pediatric intensive care units: Control of an outbreak of multiresistantKlebsiella pneumoniae in a newborn intensive care unit with this measure

Outbreaks of gram-negative colonization (generally by antibiotic-resistant enterobacteria) are common in newborn intensive care units (NICUs), and control methods are not always effective. We studied the effectiveness of an alcohol solution of N-duopropenide (NDP) in vivo (germicidal effect on flora of teams in the NICU and the pediatric intensive care unit vs handwashing with nonantiseptic soap) and its effect on the control of a multiresistant (MR) Klebsiella pneumoniae outbreak in our NICU that had persisted for 13 months, despite the use of classic control measures. For educational purposes, we also performed 4 prevalence studies of microbial hand flora in NICU staff (two before and two after introducing NDP). The alcohol solution of NDP was highly germicidal in vivo, destroying microorganisms better than classic handwashing on the hands of 69 health care staff of our NICU and PICU. The flora in both units was reduced from an average of 63% to an average of 95%. Application of this disinfectant to the hands of health care workers after handling newborns helped to eliminate the MR Klebsiella strain in our NICU, (relative risk compared with the period preceding use of the disinfectant: 8.6, with 95% confidence intervals, 4.8-145.5). Four prevalence studies of hand microbial contamination, before and after NDP introduction in the NICU, showed a significant reduction of enterobacteriaceae, mainly MR K pneumoniae , in health care workers. In conclusion, NDP in alcohol was very effective in vivo. It proved to be a useful complementary measure to handwashing and reduced exogenous microorganism transmission in a unit with a heavy patient-care workload. (Am J Infect Control 2001;29:162-7)