Category: Diseases, Syndromes and Conditions

Categories : COVID Diseases, Syndromes and ConditionsTags :

A Common Cold Virus Could Stifle COVID

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Photo by Kelly Sikkema on Unsplash

There might be an unexpected benefit to the rhinovirus, or the most frequent cause of the common cold — protection against COVID, according to a study at Yale University.

Around 200 viruses cause the common cold, of which rhinovirus is the most common. Researchers found that the rhinovirus kick-starts interferon-stimulated gene activity. Within airway tissues infected with the rhinovirus, this also can halt replication of the SARS-CoV-2 virus.

Setting off these defences early in the course of COVID infection might prevent or treat the infection, said Ellen Foxman, assistant professor of laboratory medicine and immunobiology at the Yale School of Medicine and senior author of the study. One method is treating patients with interferons, an immune system protein which is also available as a drug.

“But it all depends upon the timing,” Prof Foxman clarified.

In later stages of COVID, high interferon levels correlate with worse disease and may fuel overactive immune responses, according to previous research. But recent genetic studies show that interferon-stimulated genes may actually also be protective in cases of COVID infection.

Prof Foxman’s lab wanted to study this defence system early in the course of COVID infection.

Earlier studies by the lab had shown that common cold viruses may protect against influenza, so they decided to find out whether rhinoviruses would have the same beneficial impact against the COVID virus. The researchers infected lab-grown human airway tissue with SARS-CoV-2 and found that for the first three days, viral load in the tissue doubled about every six hours. However, replication of the coronavirus was completely halted in tissue which had been exposed to rhinovirus. When antiviral defences were blocked, the SARS-CoV-2 could replicate in airway tissue previously exposed to rhinovirus.

The same defences slowed down SARS-CoV-2 infection even without rhinovirus, but only with a low infectious dose, suggesting that the viral load at the time of exposure affects whether the body can effectively fight the infection.

The researchers also studied nasal swab samples from patients diagnosed close to the start of infection. They found evidence of rapid growth of SARS-CoV-2 in the first few days of infection, followed by activation of the body’s defenses. According to their findings, the virus typically increased rapidly for the first few days of infection, before host defenses kicked in, doubling about every six hours; in some patients the virus grew even faster.

“There appears to be a viral sweet spot at the beginning of COVID, during which the virus replicates exponentially before it triggers a strong defence response,” Foxman said.

Interferon treatment is promising but could be tricky, she said, because it would be mostly effective in the days immediately after infection, when many people are asymptomatic. In theory, interferon treatment could be used prophylactically in people at high risk who have been in close contact with others diagnosed with COVID. Interferon is being trialled in COVID, and there appears to be a benefit when given early, but not late.

The study helps explain why influenza infections are lowered at times of the year when the common cold is prevalent, Prof Foxman said. The easing of social distancing measures could cause the common cold and flu viruses, which have been suppressed, to spring back with greater force. Respiratory viruses interference with each other could be a mitigating factor, creating an ‘upper limit’ on the degree to which respiratory viruses circulate together, she said.

“There are hidden interactions between viruses that we don’t quite understand, and these findings are a piece of the puzzle we are just now looking at,” Prof Foxman said.

Source: Yale University

Journal information: Cheemarla, N.R., et al. (2021) Dynamic innate immune response determines susceptibility to SARS-CoV-2 infection and early replication kinetics. Journal of Experimental Medicine.doi.org/10.1084/jem.20210583.

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Normal Breathing Can Transport Viruses Over 2 Metres

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Researchers have demonstrated that normal breathing can transport viruses in saliva droplets up a distance of up to 2.2 metres in 90 seconds.

The World Health Organization and the Centers for Disease Control recommend social distancing to prevent the spread of COVID. The distances are estimated from various studies, but there is a need for further research into how viruses are transported from one person to another. 
Previous studies considered aerosol transport after coughing or sneezing, while this study focused on normal human breathing, using computer simulations with a more realistic model than prior studies. A normal breath produces periodic jet flows that contain saliva droplets, but those jets’ velocity is less than a tenth that of a cough or sneeze.

Wearing a face mask greatly reduces the distance which these droplets can travel. Saliva droplets restricted by a mask had travelled only 0.72 metres after two minutes, far short of the distance of 1.8 metres suggested by the CDC.

The investigators found even normal breathing produces a complex field of vortices that can move saliva droplets away from the person’s mouth. The role of these vortices has not previously been understood.

Study author, Ali Khosronejad, American Institute of Physics said: “Our results show that normal breathing without a facial mask generates periodic trailing jets and leading circular vortex rings that propagate forward and interact with the vortical flow structures produced in prior breathing cycles.”

This complex vorticity field can enable the transport of aerosol droplets over long distances despite the slow speeds. A face mask serves to dissipate the kinetic energy of the jet produced by an exhaled breath, thereby disrupting the vortices and limiting the travel of virus-laden droplets.

The researchers also took into account evaporation of the saliva droplets. With no mask, they found the saliva droplets near the front of the plume of exhaled breath had partially evaporated, reaching a size of only one-tenth of a micrometre. In stagnant indoor air, it would take days for droplets this small to settle to the ground.

Masks partially redirect the exhaled breath downward, significantly restricting forward motion of the plume, so the risk of suspended droplets remaining in the air is substantially reduced.

“To simplify the breathing process, we did not consider the flow of air-saliva mixture through the nose and solely accounted for the flow through the mouth,” Khosronejad said. “In future studies, we will explore the effect of normal breathing via both the nose and mouth.”

Source: News-Medical.Net

Journal reference: Khosronejad, A., et al. (2021) A computational study of expiratory particle transport and vortex dynamics during breathing with and without face masks. Physics of Fluids. doi.org/10.1063/5.0054204.

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Why the Origin of COVID Matters

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Photo by Artem Podrez from Pexels

As interest mounts in the ‘lab leak’ hypothesis for the origin of SARS-CoV-2, more scientists are starting to take it seriously, especially because of the important implications of its actual origins.

MedPage Today reported that many experts it approached for the story were hesitant to speculate on its exact implications, they agreed that further research into its origins is important to ward off future pandemics.

A natural origin’s implications

Back in 2007, scientists who were studying coronaviruses warned: “The presence of a large reservoir of SARS-CoV–like viruses in horseshoe bats… is a time bomb. The possibility of the re-emergence of SARS and other novel viruses… should not be ignored.”

On May 26 2021, in the midst of the greatest disaster the world has faced since World War II, US President Joe Biden gave US intelligence 90 days to reach a “definitive conclusion” on the origins of SARS-CoV-2.

Vincent Racaniello, PhD, professor of microbiology and immunology at Columbia University, said finding an answer is unlikely within Biden’s deadline. After all, it took 14 years to find the ancestor of the first SARS virus in wildlife.

For Prof Racaniello, this renewed concern underscores the need for better surveillance of viruses in wildlife.

“All human viruses begin in nature. There’s an overwhelming preponderance of data that shows that, so it makes sense to look in nature when we’re looking for the source of new viruses,” Prof Racaniello told MedPage Today.

As a result of human population pressure, more viruses are spilling over into humans from nature. Examples of this include Ebola, SARS-1, MERS, and bird and swine flu. Because of the evolutionary closeness of mammals and humans, they are major pathogen sources. Rodents and bats (accounting for 20% of mammals), as well as various species of birds are good places to look. However our surveillance of wildlife is spotty, so we have “very little” understanding of the viruses these types of animals harbour, and which ones could be threats to humans, Prof Racaniello warned.

“We need to do more wildlife sampling, to find out what’s out there and what’s potentially a threat,” he said. “More investment in this could have prevented the trillions of dollars that we’ve spent to take care of this pandemic.”

A lab leak’s implications

On the other hand, Richard Ebright, PhD, a molecular biologist and professor of chemistry and chemical biology at Rutgers University in New Jersey, believes the real issue lies in addressing the potential for future pandemics that could originate from lab accidents, a discussion that “needs to begin now.”

“Irrespective of whether COVID originated in a natural accident or a lab accident, the risk of a future pandemic originating in a lab accident is real,” he told MedPage Today.

Prof Ebright explained that, in the US and other countries, only voluntary biosafety guidelines exist, and these are about preventing accidental release of pathogens. While the US has legal regulations against several pathogens that could be used as biological weapons, there are no biosecurity regulations for other pathogens. In most of the world, no biosecurity regulations exist for pathogens other than smallpox, not even voluntary ones, Prof Ebright said.

In 2017, the US implemented a bio-risk policy requiring a risk-benefit analysis before federal funding can be approved for high-risk research, such as ‘gain of function’ research that could be used to increase a pathogen’s transmissibility or pathogenicity to better understand and control it, Prof Ebright said. But this bio-risk policy has been essentially ignored by federal agencies, and the other countries with bio-risk policies only apply it to smallpox.

“Discussion now, especially among policy makers and the public, needs to turn to the inadequacy of biosafety, biosecurity, and biorisk-assessment standards worldwide, and to the essentially complete absence of biosafety regulation worldwide,” he said.

The return of the lab leak hypothesis

While evidence is largely circumstantial, the basic idea is that a laboratory at the Wuhan Institute of Virology had been experimenting on a virus called RaTG13 (a coronavirus closely related to SARS-CoV-2, which infects horseshoe bats), and genetically manipulating other horseshoe bat viruses collected around China. It is thought that one of these laboratory viruses could have infected a staffer at the institute, who then transmitted it to the broader public, Dr Ebright explained.

Following the WHO’s March 30 SARS-CoV-2 origins investigation report, there was a sudden about-face and the lab leak theory began to be taken seriously. Though investigators classified a laboratory origin as “extremely unlikely”, they said the conclusion was reached on the evidence made available.

Even the Director-General of the WHO, Dr Tedros Ghebreyesus, said at the time that he did not believe the assessment of a laboratory origin was “extensive enough,” that this hypothesis “requires further investigation,” and that “this report is a very important beginning, but it is not the end.”

“At this point in time, all scientific data related to the genome sequence of SARS-CoV-2 and the epidemiology of COVID are equally consistent with a natural-accident origin or a laboratory-accident origin,” Ebright said.

While the WHO report does not propose a follow-up study for laboratory origins, it acknowledges that both “follow-up of new evidence” and “regular administrative and internal review of high-level biosafety laboratories worldwide” is needed.

Source: MedPage Today

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UTI Bacteria Traced to Meat Production

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A Portuguese study has found that bacteria in urinary tract infections (UTI) can be traced back to meat through the production chain where it was prepared.

UTIs are caused by both Gram-negative and Gram-positive bacteria, as well as by certain fungi. Staphylococcus saprophyticus is a major cause of UTI in young women, reaching 20% prevalence. Understanding the epidemiology of this microorganism can help identify its origin, distribution, causes, and risk factors. Researchers from ITQB NOVA led by Maria Miragaia showed that Staphylococcus saprophyticus can originate in food, specifically in the meat-production chain. Their findings were published in the journal Emerging Infectious Diseases.

Pork is the most popular meat type in Europe. S. saprophyticus can be a contaminant of that meat, and it is also found in the environment, the gut and rectal flora of pigs, and in the human gastrointestinal tract, vagina, and perineum.

The researchers used a combination of phenotypic, genomic, and pan-genome wide association approaches, which enabled them to identify two different lineages (G and S) of S. saprophyticus. Lineage G is of food origin and transmitted to humans by contact with food products, and lineage S is of human origin. Both cause disease and may be transmitted directly or indirectly between persons within the community, with an extensive geographic distribution possible.

To find out if these bacteria causing UTIs could be related to the ones found in pork, the research group looked at S. saprophyticus from a slaughterhouse and compared them to those causing human UTIs. The team analysed bacteria collected from UTIs worldwide over two decades, and from UTIs and pork meat production chain in Portugal.

The results showed that bacteria found in the slaughterhouse (equipment, meat, colonisation of workers) were similar to human UTI bacteria and had the same antibiotic resistance profile.

Although S. saprophyticus colonisation rate in pigs was extremely low (1%), 35% of slaughterhouse samples were contaminated. The presence of an antiseptic resistance gene (qacA) by all the lineage G bacteria could be part of the explanation for the ineffective cleaning procedures that were used. 
“S. saprophyticus strains of animal origin (lineage G) enters the slaughterhouse through food animals, persist on the equipment, disseminate and contaminate the meat processing chain and humans. Human colonisation is a crucial step for the later occurrence of UTI,” explained first author Opeyemi Lawal.

The researchers also studied genomic data of bacteria collected from patients attending three hospitals in the Lisbon area, and found that the transmission of these pathogenic bacteria from both lineages (G and S) occurs between persons within the community. Making use of this deep-structured analysis, researchers were also able to identify putative new virulence factors for this unexplored bacterium. The team will continue to search for reservoirs of this bacterium in humans and animals, and to study the mechanisms of S. saprophyticus dissemination and disease to inform strategies against  this pathogen. 

“This a clear example of how food manipulation can impact in human health, and how important it is to educate consumers regarding good individual hygiene practices to avoid spreading of infectious diseases“, said Maria Miragaia, head of the Bacterial Evolution and Molecular Epidemiology Lab. 

“This adds to the list of bacteria that are transmitted to humans through contact with animals and animal-derived food. But the exact mechanisms associated to the conversion from a coloniser to an infectious agent remains to be clarified”, added Henrik Westh from the Copenhagen University Hospital – Amager and Hvidovre, University of Copenhagen (Denmark).

Source: ITQB NOVA

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First Detection of Zika Viral DNA in African Bats

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Image source: Ekamalev at Unsplash

Researchers have, for the first time, detected Zika virus RNA in free-ranging African bats, which indicates that the bats were previously infected with Zika virus at the time the samples were taken. 

This discovery also marks the first time scientists have published a study on the detection of Zika virus RNA in any free-ranging bat.

The findings have ecological implications and raise questions about how bats are exposed to Zika virus in the wild. The study was led by Dr Anna Fagre, a veterinary postdoctoral fellow at Colorado State University’s Center for Vector-Borne Infectious Diseases. The findings were detailed in the journal Scientific Reports.

Dr Fagre said that while other studies have shown that bats are susceptible to Zika virus in controlled experimental settings, detection of nucleic acid in bats in the wild indicates that it was transmitted by bites from infected mosquitoes.

“This provides more information about the ecology of flaviviruses and suggests that there is still a lot left to learn surrounding the host range of flaviviruses, like Zika virus,” she said. Other flaviviruses that cause disease in humans include West Nile and dengue.

Wide-ranging samples

Senior author Rebekah Kading, Assistant Professor at CSU, said she, Dr Fagre and the research team were hoping the project would help them to find out more about potential reservoirs of Zika virus.

With 198 samples from bats gathered in the Zika Forest and surrounding areas in Uganda, the team confirmed Zika virus in four bats representing three species. The samples date back as far as 2009 from different parts of Uganda, which is years before the large Zika outbreaks in 2015 to 2017 in North and South America.

The Zika virus was declared a public health emergency by the World Health Organization in February 2016 owing to its association with the congenital deformities, particularly microcephaly in infants borne to the infected mothers

“We knew that flaviviruses were circulating in bats, and we had serological evidence for that,” said Prof Kading. “We wondered: Were bats exposed to the virus or could they have some involvement in transmission of Zika virus?”

The virus detected by the team in the bats was most closely related to the Asian lineage Zika virus, the strain that caused the epidemic in the Americas following outbreaks in Micronesia and French Polynesia. The Asian lineage Zika virus was in late 2016 first detected in Africa, in Angola and Cape Verde.

“Our positive samples, which are most closely related to the Asian lineage Zika virus, came from bats sampled from 2009 to 2013,” said Prof Fagre. “This could mean that the Asian lineage strain of the virus has been present on the African continent longer than we originally thought, or it could mean that there was a fair amount of viral evolution and genomic changes that occurred in African lineage Zika virus that we were not previously aware of.”

Likely incidental hosts, not reservoirs

Prof Fagre said that the relatively low prevalence of Zika virus found indicates that bats may only be incidental hosts of Zika virus infection, rather than amplifying hosts or reservoir hosts.

“Given that these results are from a single cross-sectional study, it would be risky and premature to draw any conclusions about the ecology and epidemiology of this pathogen, based on our study,” she said. “Studies like this only tell one part of the story.”

The research team also made an assay for the study which focuses on subgenomic flavivirus RNA, sfRNA, which flaviviruses possess. Testing for Zika normally uses PCR, polymerase chain reaction, to identify bits of genomic RNA, the nucleic acid that results in the production of protein, said Fagre.

The team’s next steps will be to characterise how long these RNA fragments persist in tissues, which will allow them to estimate how long ago these bats were infected with Zika virus, Prof Kadling said.

“There is always a concern about zoonotic viruses,” she said. “The potential for another outbreak is there and it could go quiet for a while. We know that in the Zika forest, where the virus was first found, the virus is in non-human primates. There are still some questions with that as well. I don’t think Zika virus has gone away forever.”

Source: Colorado State University

Journal information: Fagre, A. C., et al. (2021) Subgenomic flavivirus RNA (sfRNA) associated with Asian lineage Zika virus identified in three species of Ugandan bats (family Pteropodidae). Scientific Reports. doi.org/10.1038/s41598-021-87816-5.

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New Antibody Treatment for Crimean-Congo Haemorrhagic Fever

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Deer tick (Ixodes scapularis). Photo by Erik Karits on Unsplash

Working with international colleagues, US Army scientists have developed and tested an antibody-based therapy to treat Crimean-Congo haemorrhagic fever virus (CCHFV). 

The deadly virus is carried by ticks and has a high mortality rate, killing up to 60% of those infected. Their findings are published in the journal Cell.

The researchers characterised the human immune response to natural CCHFV infection by using blood samples donated by disease survivors. They were able to identify several potent neutralising antibodies that target the viral glycoprotein–a viral component which has a key role in disease development. A number of of these antibodies, administered individually or in combination, successfully protected mice from CCHFV when exposed to the virus after antibody administration.

In order to treat mice that had already been infected with the virus, the team created ‘bispecific’ antibodies that combined potency with the ability to bind to two different sites on the CCHFV glycoprotein. One of these bispecific antibodies, called DVD-121-801, overcame CCHFV infection in mice with just a single dose administered 24 hours after challenge with live virus.

DVD-121-801 as a potential therapeutic for human patients, according to co-first author Andrew H. Herbert, Ph.D., of the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID).

CCHFV is the most prevalent tick-borne virus that causes human disease, and is endemic in countries across Europe, Asia, and Africa. CCHF occurs most frequently among agricultural workers following the bite of an infected tick, and to a lesser extent among slaughterhouse workers exposed to the blood and tissues of infected livestock and medical personnel through contact with the body fluids of infected patients. In spite of its high lethality and widespread distribution, there are no vaccines or specific treatments for it. It has been designated a priority pathogen by the World Health Organization.

Study co-first author Andrew H Herbert, PhD, US Army Medical Research Institute of Infectious Diseases, said: “Rodent models of CCHFV infection are useful in testing and down-selecting neutralising antibodies. However, to advance a lead candidate for therapeutic use, it will be necessary to conduct studies in larger animal models that more faithfully recapitulate human disease.”

Source: Medical Xpress

Journal information: J. Maximilian Fels et al, Protective neutralizing antibodies from human survivors of Crimean-Congo hemorrhagic fever, Cell (2021). DOI: 10.1016/j.cell.2021.05.001

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China Reports First Human Infection of the H10N3 Avian Flu Strain

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Image by Arek Socha from Pixabay

On Tuesday, China reported the world’s first human infection of the H10N3 avian flu strain but said the risk of its widespread transmission among people was low.

In the eastern city of Zhenjiang, a 41-year-old man was admitted to hospital with fever symptoms on April 28 and a month later was diagnosed with H10N3, China’s National Health Commission (NHC) said in an online statement.

The NHC said that “The risk of large-scale spread is extremely low,” and that the man was in a stable condition with his close contacts having reported no “abnormalities”.

The health body described H10N3 as being low pathogenic, ie less likely to cause death or severe illness, in birds. It said there had been no human cases of H10N3 previously reported anywhere in the world.

A number of strains of bird flu have been found among animals in China but mass outbreaks in humans are rare.

Five waves of the H7N9 influenza epidemic occurred in China between March 2013 and September 2017. Low pathogenicity H7N9 dominated in the first four waves, whereas highly pathogenic H7N9 influenza emerged in poultry and spread to humans during the fifth wave, causing widespread concern.  

H7N9 has infected 1668 people and claimed 616 lives since 2013, according to the United Nations’ Food and Agriculture Organization. In the wake of recent avian flu outbreaks in Africa and Eurasia, the head of China’s Centre for Disease Control and Prevention last week urged closer surveillance in poultry farms, markets and wild birds.

COVID was first detected at a wet market with food and live animals in the central Chinese city of Wuhan in late 2019. This is where, according to the most likely scenario from the WHO report on the virus’ origins, it is thought that the SARS-CoV-2 virus first jumped from animals to humans. 

Source: Medical Xpress

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Gene Drive to Control Mosquito-borne Disease a Step Closer

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Image source: Ekamalev at Unsplash

Scientists have developed a set of tools that will help create a gene drive to control mosquito-borne diseases such as the West Nile virus, which has received less attention than controlling mosquitoes that transmit malaria.

Since the advent of CRISPR genetic editing revolution, scientists have been working to use the technology to develop gene drives that target pathogen-spreading mosquitoes such as Anopheles and Aedes species, which spread malaria, dengue and other life-threatening diseases.

Much less genetic engineering work has focused on Culex genus mosquitoes, which spread devastating afflictions stemming from West Nile virus, as well as other viruses such as the Japanese encephalitis virus (JEV). Culex mosquitoes are a significant health risk in Africa and Asia, where they transmit the worm causing filariasis, a disease that can lead to a chronic debilitating condition known as elephantiasis.

University of California San Diego scientists have now developed a number of genetic editing tools that will help create a gene drive designed to stop Culex mosquitoes from spreading disease. Gene drives are designed to spread modified genes, in this case those that disable the ability to transmit pathogens, throughout the targeted wild population. The new study is published in the journal Nature Communications,

The researchers developed a Cas9/guide-RNA expression ‘toolkit’ designed for Culex mosquitoes. Since so little genetic engineering work has been done on Culex mosquitoes, the researchers were required to develop their toolkit from scratch, starting with a careful examination of the Culex genome.

“My coauthors and I believe that our work will be impactful for scientists working on the biology of the Culex disease vector since new genetic tools are deeply needed in this field,” said Gantz, an assistant research scientist in the Division of Biological Sciences at UC San Diego. “We also believe the scientific community beyond the gene drive field will welcome these findings since they could be of broad interest.”

The researchers also demonstrated the applicability of their tools in other insects.

“These modified gRNAs can increase gene drive performance in the fruit fly and could potentially offer better alternatives for future gene drive and gene-editing products in other species,” said Gantz.

Gantz and his colleagues have now tested their new tools to ensure proper genetic expression of the CRISPR components and are now on the verge of applying them to a gene drive in Culex mosquitoes. This could be used to stop pathogen transmission by Culex mosquitoes, or alternatively employed to suppress the mosquito population to prevent biting.

Source: University of California San Diego

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SA Study Finds That Influenza is Widely Spread by Asymptomatic Cases

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Image by Arek Socha from Pixabay

A new study investigated the prevalence and transmission of influenza in rural and urban South Africa communities.

The study was conducted by the National Institute for Communicable Diseases (NICD), Perinatal HIV Research Unit (PHRU), WITS Agincourt HDSS in partnership with the US Centers for Disease Control and Prevention (CDC), who also funded the study. 

Influenza, a communicable viral disease caused by a spectrum of influenza viruses, affects the upper respiratory tract, including upper and lower respiratory passages. The virus can be transmitted in droplets from coughing, talking or sneezing, and through touching contaminated surfaces.

Researchers enrolled 100 rural and urban households in South Africaeach year and observed them for 10 months. Systematic twice-weekly nasopharyngeal sampling of all household members were conducted, with samples tested by polymerase chain reaction (PCR) for influenza. A total of 81 430 samples were collected from 1116 participants in 225 households, out of which 917 (1%) tested positive for influenza and 79% of households (178/225) had ≥1 influenza-positive individual.

The burden of was high in a rural and an urban African setting, the study revealed, with over three-quarters of households and more than one in three individuals experiencing at least one flu infection each year. It is important to note that the flu incidence risk was similar between the rural and urban areas who participated in the study. The study also showed that recurring flu infections in the same annual flu epidemic, particularly in children, were a common occurrence, accounting for 15% of those infected. Young children also experienced the highest burden of flu infection and symptomatic illness — and compared to other age groups, they were more likely to spread the flu to others in their household.

In addition, the study also revealed that slightly over half of the flu infections were symptomatic. Asymptomatic individuals were also able to spread flu, transmitting the flu to approximately 6% of household contacts. For this reason, authors of the study believe asymptomatic infections to be an important driver of flu transmission.

Medically attended influenza-associated influenza like illness (ILI), defined as a fever and cough as captured by the World Health Organization-recommended flu surveillance programs, suggests the prevalence of flu within communities may be much higher than observed at healthcare facilities. Understanding the community burden and transmission of seasonal influenza is crucial for vaccination programmes and non-pharmaceutical interventions, as well as pandemic preparedness.

In conclusion, the study provides important data on the community burden of flu and transmission thereof in an African setting, a topic that hasn’t been adequately explored. It also contributes important findings relating to symptomatic and asymptomatic flu transmissions, and has implications for the use of non-pharmaceutical interventions and vaccination strategies that target children.

A similar study to examine the burden and transmission of SARS-CoV-2 in the same communities including the role of asymptomatic infections in the spread of SARS-CoV-2 was initiated in July 2020 and results of this study are expected in the coming months.

Source: National Institute for Communicable Diseases

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New Way to Compare Effectiveness of Tuberculosis Treatments

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E. Coli bacteria. Image by CDC

A new study published in Nature Communications provides an important new basis for comparing the varying effectiveness of tuberculosis treatments.

Tuberculosis is a ancient disease caused by the bacterium Mycobacterium tuberculosis (Mtb) and aside from the COVID pandemic, is still the leading infectious cause of death globally, killing 1.2 million people each year. The availability of a new way to evaluate treatments can save lives.

In the study, the researchers aimed to provide a new perspective on assessing the effectiveness of tuberculosis drugs.

“A key roadblock that holds back new tuberculosis treatments is our current inability to accurately measure how effectively different treatments shorten the time needed to cure tuberculosis,” said lead author Nicholas Walter, MD, Ph.D., associate professor at the University of Colorado Anschutz Medical Campus. “Without improved tools to measure and compare the effectiveness of drug treatments, the evaluation and roll-out of new combination drug treatments will continue to proceed slowly.”

“In the past, the effectiveness of tuberculosis treatment has been judged by estimating the burden of the pathogen M. tuberculosis as enumerated via culture based approaches. This historical method correlates poorly with what we care about most, which is whether tuberculosis patients are durably cured,” added co-first author Gregory Robertson, PhD, assistant professor at Colorado State University.

By Vossman - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=6865434
Structure and shape of the E.coli 70S ribosome. The large 50S ribosomal subunit (red) and small 30S ribosomal subunit (blue) are shown with a 200 Ångstrom (20 nm) scale bar.

The researchers measured the extent to which drugs interrupt the synthesis of ribosomal RNA, which is needed for the protein-making machinery of the bacterium. They found that drugs and drug regimens that treat tuberculosis faster inhibit Mtb rRNA synthesis more than less potent drugs and regimens. Their resulting new measure, called the rRNA synthesis (RS) Ratio is a useful molecular metric of drug activity based on a key microbial physiologic property rather than a simple measure of reducing bacterial burden.

“The RS Ratio gives us a readout of drug effect that opens a new era in understanding antibiotics. Measuring a key physiologic property of pathogens provides an innovative way of thinking beyond conventional measures of bacterial burden,” said senior author Martin Voskuil, PhD, associate professor at the University of Colorado Anschutz Medical Campus.

“The RS Ratio can enable more intelligent design and evaluation of candidate drug combination regimens, accelerating the development of treatments that can cure tuberculosis faster. This has crucial implications for combatting the global tuberculosis epidemic,” addrf co-author Payam Nahid, MD, MPH, professor and director of the University of California San Francisco Center for Tuberculosis.

Source: Medical Xpress