How to fight a complex, unpredictable virus

/0 Comments/in , /by

Only quality clinical and health sciences research and innovation will provide the technological base for Bangladesh to successfully counter this and future medical emergencies. Photo: Dado Ruvis/Reuters

Professor Ahmed Abdullah Azad PhD, Secretary General, Islamic-World Academy of Sciences

Bangladesh had three-months’ notice to prepare for a possible outbreak of Covid-19 but failed to prepare for it. The authorities have tried very hard to convince everyone to use the public health measures that are known to minimise community transmission, but these have not been easy to implement in the densely populated environment of Bangladesh. Lack of coordination, insufficient testing, contradictory and inconsistent directives, and an eagerness to prematurely reopen businesses, have allowed Covid-19 to spread to all corners of the country. Large numbers of healthcare workers, policemen, journalists, transport workers, and other frontline workers, have worked tirelessly and selflessly to help stop the carnage, and in the process far too many of them have paid dearly with their lives.

With rampant infection and death rates increasing every day, and faced with the resulting economic freefall, the government has decided to divide the country into non-contiguous red, yellow and green zones, and impose lockdown in the red zones first. Till now only a very small number of red zones with the highest number of infections have been locked down on an experimental basis. More experiments will waste valuable time and further delay may see more yellow zones turning red, and more green zones turning yellow. An all-out war has to be launched against the virus in all red zones simultaneously through total lockdown (not public holiday!) enforced if required with curfews and troop deployment, together with extensive testing to identify infected individuals and their close contacts, followed up with their isolation and treatment in designated public buildings within the red zones.

The obvious weak links in fighting Covid-19 are low capacity of RT-PCR testing and ineffective contact tracing. For contact tracing, the authorities could invite young people living within a red zone to help in neighbourhood surveillance—a strategy that has worked very well in Vietnam’s fight against Covid-19. The huge numbers of tests needed in each red zone is simply not possible with RT-PCR because of the limited availability of very expensive equipment and reagents and shortage of trained personnel. To complement RT-PCR testing, the government should seriously consider the use of alternative tests that are inexpensive, rapid and not dependent on specialist equipment or personnel.

To cope with a second wave of Covid-19 in sizable parts of Melbourne (Australia), besides total lockdown a RT-PCR testing blitz has also been launched in which saliva has been substituted for throat and nose swabs. About two months back Bangladeshi media reported on a rapid antigen detection kit, developed by Gonoshasthya Kendra-RNA Biotech Ltd., that also detects SARS-CoV-2 in saliva samples. While RT-PCR test detects viral RNA, the rapid antigen test detects viral surface proteins. So, both tests should essentially provide the same information about the presence or absence of virus.

CARES is committed to giving the society the right information about the COVID -19.  Only scientific discussions by practising scientists from Bangladesh and other places are in CARES website.  Here are some new insightful suggestions from Professor Dr Jeba Seraj, an active member of CARES and a life scientist at Dhaka University. At CARES we talk science.  Engage Science in your life.   –  Wali-ul-Maroof Matin, Chairman, CARES

However, the locally-produced rapid antigen kit is claimed to provide results within 10 minutes, does not require any equipment or trained manpower, and costs only a fraction of RT-PCR. These claims should be verified independently by using the same saliva sample for both RT-PCR and rapid antigen tests. If validated and approved by DGDA, this inexpensive and simple homegrown kit would be ideal for rapid testing and follow up of a large number of people in the red zones. A rapid antibody detection kit (also developed by GK-RNA Biotech) which has been approved by DGDA for studying antibody response to Covid-19 could nicely complement the rapid antigen kit, as together, they would identify all infected individuals who have also seroconverted. The rapid antibody kit can also be used as a powerful research tool to ask and answer a number of fundamental questions about the consequences of Covid-19 infection.

Antibody testing of blood from Covid-19 patients has yielded some unexpected results. A recent study showed that 3 percent of RT-PCR positive patients failed to produce antibodies against Covid-19 and 4 percent of patients who were RT-PCR negative were correctly picked up by antibody test (Quan-Xim Long et al, Nature Medicine, April 2020). Another study from John Hopkins University also shows (Annals of Internal Medicine, 2020) that RT-PCR can produce 20 percent false negatives. This demonstrates the value of using RT-PCR/antigen test and antibody test in parallel. In another study comparing Covid-19 symptomatic and asymptomatic patients, antibody response was found to be much weaker in the asymptomatic group, and within 8 weeks of infection 40 percent of asymptomatic and 13 percent of symptomatic patients showed no antiCovid-19 antibodies in their blood (Quan-Xin Long et al., Nature Medicine, June 2020). This brings into question the prospects of long-term natural or vaccine-induced immunity.

The rapid antibody test could also be useful in selecting suitable plasma donors from among recovered patients. Analyses of 370 plasma samples from Covid-19 recovered patients showed that almost 17 percent had almost no antibody response, and while over 80 percent generated varying levels of antibody, only about 10 percent had high levels of neutralising antibodies able to neutralise a laboratory-safe Covid-19 pseudovirus (New York Blood Centre and Rockefeller University, medRxiv, 2020). The above studies show that plasma from asymptomatic and seronegative recovered patients will be of little utility, and only about 10-12 percent of the seropositive plasma will be suitable for harvesting and enrichment of strong antiCovid-19 neutralising antibodies. This could be the first step towards developing a therapeutic vaccine.

Although an effective prophylactic vaccine is highly desirable, there is no guarantee that one will be produced soon or be available to Bangladesh. Attempts to produce effective vaccines against many pathogens has failed even after years of trying, and it would not be wise to put all our eggs in the vaccine basket. It is quite possible that deliverance may come not from a preventive vaccine but from drugs as happened with HIV/AIDS. A previous op-ed (Covid-19: Taming the Beast, The Daily Star, April 14, 2020) pointed to some therapeutic approaches that Bangladeshi scientists could try using with Bangladesh’s own capabilities and strengths. Bangladeshi scientists have demonstrated that full genome sequencing is well within their capability, but instead of being in a race to be the first or who can sequence the most viral genomes, they could collaborate on trying to understand why different people react differently to Covid-19, why some infected people remain asymptomatic, and why some infected patients never produce antiCovid-19 antibodies.

The Covid-19 pandemic has exposed the very poor state and safety of our health services and hospitals, shortage of trained healthcare workers, and insufficient testing capacity needed to meet the challenge. Covid-19 has also doubled the number of “very poor” to 40 million. An annual budget in the middle of the Covid-19 pandemic would have been expected to specifically make special allocations for the health, wellbeing and rehabilitation of the poorest and most vulnerable, for improving hospital treatment and public health, and educating and training of adequate numbers of clinicians and healthcare workers.

Covid-19 is not about to disappear soon, and could come back in future in a more deadly form. Only quality clinical and health sciences research and innovation will provide the technological base for Bangladesh to successfully counter this and future medical emergencies. Unfortunately, the token increase in health and education budgets are not enough to have much impact on bringing about the above changes or building technological capacity for the future. Perhaps Covid-19 will nudge our policymakers to realise that investment in health, education and medical research today will be a lasting investment in a healthy, just and prosperous Bangladesh.

Ahmed A Azad is a retired academic and biomedical scientist, who has had a lifelong involvement in the discovery, development and commercialisation of biotech vaccines and drugs.

Email: aaazad1945@gmail.comc

Source: https://www.thedailystar.net/opinion/news/how-fight-complex-unpredictable-virus-1927713

কোভিড-নাইন্টিন রোগ – দ্বিতীয় ঢেউ-এর প্রস্তুতি

/0 Comments/in , /by

মোহাম্মদ আশরাফ হোসেন, ফেলো হিসেবে US FDA তে ৮ বছর কর্মরত ছিলেন, ফ্লোরিডা, ইউএসএ

‘ঢেউ-এর পর ঢেউ’- ভাবতেই সাগরের ঢেউ বালুকাবেলায় আছড়ে পড়ার মনোমুগ্ধককর দৃশ্য মনে পড়ে। কিন্তু এপিডেমিওলোজী পরিভাষায় ঢেউ বা ওয়েভ-এর অর্থ সংক্রামক ব্যাধির প্রত্যাবর্তন, যা অনাকাঙ্খিত।

নীরব ঘাতক কোভিড-১৯ রোগ সংক্রমণ শুরু হয়েছিল গত বছরের ডিসেম্বরে চীনের ঊহানে; আর তা মাত্র কয়েক মাসে সারা বিশ্বে ছড়িয়ে পড়ে। এ রোগে এ যাবৎ আক্রান্ত হয়েছে ৩২ লক্ষাধিক মানবসন্তান, আর মাত্র কয়েক মাসে মৃত্যু হয়েছে প্রায় ২.৩ লক্ষাধিক। শিল্পোন্নত দেশ যুক্তরাষ্ট্রে মৃত্যু সংখ্যা সর্বাধিক, প্রায় ৬৩ সহস্র।  মৃত্যুর মিছিলে শত-সহস্র যোগ হচ্ছে প্রতিদিন। যেমন, বিগত ২৪ ঘন্টায় যুক্তরাষ্ট্রে প্রায় ২ সহস্র (শুধু নিউ ইয়র্কে ৩০৬), যুক্তরাজ্যে ৬৭৪, মেক্সিকোতে ১৬৩, ব্রাযিলে ৩৯০ আর বাংলাদেশে অন্ততঃ ৫ জনের মৃত্যু হয়েছে।  ইওরোপের বিভিন্ন দেশে শত-সহস্র সংক্রমণ ও মৃত্যু লক্ষণীয়। এরই মধ্যে আশার বাণী কিংবা গুঞ্জন শোনা যাচ্ছে- করোনাভাইরাস নাকি দূর্বল হয়ে গেছে। তারই ভিত্তিতে লকডাউন উপেক্ষা করার প্রবণতা বাড়ছে। যুক্তরাষ্ট্রের লকডাউন শিথিল এলাকার গাড়ি চলাচল বেড়েছে আর সী-বীচ, বোট ক্লাব আর পার্কগুলিতে বিপুল জনসমাগম হচ্ছে। লকডাউন প্রত্যাহারের দাবীতে জনসমাবেশ হয়েছে কয়েকটি শহরে। নতুন সংক্রমণ কিংবা মৃত্যুহারে সামান্য নিম্নগতি কিছুটা আশার সঞ্চার করলেও এ মুহূর্তে কোভিড-১৯ রোগ পরাস্ত কিংবা নিষ্ক্রমণের দাবী আর যাই হোক যুক্তিসঙ্গত নয়।

স্বাধীনতাহীন, গৃহবন্দী, অলস ও বেকার জীবন কেউ চায় না।  কিন্তু ঊহানে কোভিড-১৯ এর প্রাদূর্ভাব শুরু হলে বাধ্যতামূলক লকডাউন, পিপিই বা সুরক্ষা সামগ্রী ব্যবহার ও সামাজিক দূরত্ব রক্ষার মাধ্যমে আড়াই মাস পর শহরবাসী মহামারীর কালো থাবা থেকে রক্ষা পেয়েছিল। এখন তারা সুস্থ-স্বাভাবিক জীবনযাপন করছে এমন দাবী করলেও বাস্তবে তা ঘটেনি; প্রায় অর্ধেক ব্যবসা প্রতিষ্ঠান এখনও বন্ধ। ফলে অর্থনৈতিক মন্দা দৃশ্যমান। এছাড়া নতুন করে সহস্রাধিক রোগ সংক্রমন ছাড়াও গত সপ্তাহে সেখানে ১৯ জন উপসর্গহীন রোগী পাওয়া গেছে।

লকডাউন ও সামাজিক দূরত্ব রক্ষা করতে গিয়ে যুক্তরাষ্ট্রে গত ৬ সপ্তাহে বেকারত্ব তিন কোটি ছাড়িয়েছে। সারা বিশ্বের বহু দেশে এখনো লকডাউন মেনে চলতে বলা হলেও গৃহবন্দী-দশা ও অর্থনৈতিক বিপর্যয়ের কারণে যুক্তরাষ্ট্রসহ বিভিন্ন দেশে যে ব্যাপক তোড়জোড় শুরু হয়েছে তা মঙ্গলজনক কিনা বলা মুশকিল। ভয়কে জয় করতে সাহসের প্রয়োজন, কিন্তু শত্রুকে দূর্বল ভেবে দূ;সাহসীর পরাজয়ের ঘটনা ইতিহাসে বিরল নয়। সুইডেন ও নরওয়ে প্রতিবেশী দেশ হলেও নরওয়ের তুলনায় সুইডেনে (লকডাউনে গুরুত্ব না দেওয়ায় ) সংক্রমণ ও মৃত্যুহার বেশী।

মনে রাখা দরকার,  করোনাভাইরাস একটি আরএনএ-ভাইরাস যার সংক্রমণ ক্ষমতা ব্যতিক্রমী; এরা ভূখন্ড, ভাষা, জাতি, সতর্কবার্তা কিংবা ধর্মের বাছ-বিচার করে না।  রোগ উপসর্গের অনুপস্থিতি কিংবা লক্ষণ রোগভিত্তিক না হওয়ায় পরীক্ষা-নিরীক্ষা ছাড়া শ্বাসতন্ত্রের এ রোগ নিরূপণ করাও কঠিন। আবার অত্যাধুনিক প্রযুক্তি ব্যবহার করে পিসিআর- টেস্ট কিংবা সেরোলজিক্যাল টেস্ট থেকে গুণগত (অর্থাৎ, পযিটিভ বা নেগেটিভ) ফলাফল পাওয়া গেলেও এদের কার্যকারিতা শতভাগ নিশ্চিত নয়।  সেরোলজিক্যাল টেস্ট এর মাধ্যমে সাধারণতঃ করোনাভাইরাস অ্যান্টিবডি (প্রতিরোধী আমিষ) সনাক্ত করা হয়; টেস্ট পযিটিভ হলে সাধারণতঃ তা শুধুই সংক্রমণ ইঙ্গিত করে। অপরপক্ষে, করোনা ভাইরাস টেস্টের ফল নেগেটিভ হলে ব্যক্তি রোগমুক্ত কিংবা ঝূকিমুক্ত, এমন দাবী করাও অসঙ্গত। বরং উপসর্গহীন আক্রান্ত ব্যক্তি অথবা মিথ্যা-নেগেটিভ একজন বাহক মিথ্যা স্বস্তি নিয়ে অন্যদের সান্নিধ্যে এসে অজান্তেই কোভিড-১৯ রোগ বিস্তারে সহায়তা করতে পারেন। আবার, পর্যাপ্ত ইম্যুনিটি বা প্রতিরোধক্ষমতার অভাবে একবার সেরে উঠার পর কোন ব্যক্তি আবারও করোনাভাইরাসে আক্রান্ত হতে পারেন।

সার্বিক পরিস্থিতি নিয়ন্ত্রনে না এলেও এ সপ্তাহে যুক্তরাষ্ট্রের প্রায় দু-ডজন রাজ্যে লকডাউন শিথিল করে সতর্কভাবে পর্যায়ক্রমে ব্যবসা-কর্মস্থল খোলার প্রস্তুতি চলছে। তবে মধ্য-মে’র আগে  নিউ ইয়র্কের অফিস-ব্যবসা খোলার সম্ভাবনা কম। ওয়াশিংটন ডিসির একজন প্রশাসক বলেছেন তিনি স্বল্প পরিসরে লকডাউন শিথিল করতে আগ্রহী। তিনি মনে করেন, রাজধানী ডিসি স্বাভাবিক হতে তিন মাস পর্যন্ত লেগে যেতে পারে। যুক্তরাষ্ট্রের করোনা পরিস্থিতি অগ্রাহ্য করা হলে কোভিড-১৯ এর প্রভাব আগামী শরত এমনকি শীতকাল পর্যন্ত দীর্ঘায়িত হতে পারে, এমন আশংকাও আছে।

প্রসঙ্গতঃ উল্লেখ্য, সংকুচিত সময়সূচি মেনে নিউ ইয়র্কের পরিবহণ সংস্থা ‘এমটিএ’ সাবওয়ে ও বাস সার্ভিস চালু রেখেছে। কিন্ত হটস্পট নিউ ইয়র্কে কোভিড-১৯-এ উল্লেখযোগ্য সংখ্যক স্বাস্থ্যকর্মী ছাড়াও অন্ততঃ ৮০ জন এমটিএ-কর্মী মৃত্যুবরণ করেছেন। এপ্রিলের ৯ এবং ৩০ সন্ধ্যায় নিউ ইয়র্কের এম্পায়ার স্টেট বিল্ডিং-এ এই দুই প্রথম সারির যোদ্ধাদের সম্মানে নীল আলোকসজ্জা করা হয়েছে।

জনবহুল বাংলাদেশে অন্যান্য দেশের তুলনায় কম হলেও নতুন কোভিড-১৯ রোগী সনাক্তকরণ ও মৃত্যু অব্যাহত আছে। সম্প্রতি ময়মনসিংহ ও নারায়নগঞ্জে বহু স্বাস্থ্যকর্মী কোভিড-১৯ এ আক্রান্ত হয়েছেন। পেশাজীবীদের মধ্যে ডাক্তার, সাংবাদিক ও পুলিশ সদস্যের মৃত্যু ঘটেছে। এছাড়া চট্টগ্রামে দুইজন ব্যক্তি দ্বিতীয় বার সংক্রমিত হয়েছেন। এসব সংবাদ দূশ্চিন্তার উদ্রেক করে। সীমিত আকারে বলা হলেও সহসাই লকডাউন শিথিল করে বহু সংখ্যক গার্মেন্টস শিল্প-কারখানা ও পবিত্র রমযানের কারণে ইফতারি/খাবারের দোকান চালু হয়েছে। গার্মেন্টস কর্মীরা চাকুরি বাঁচাতে নিকট ও দুরের জেলা থেকে কর্মস্থলে এসেছেন, অথচ যানবাহন চলাচলে নিষেধাজ্ঞা থাকায় অস্বাস্থ্যকর অবস্থায় ভ্রমণ করেছেন। স্বাস্থ্যবিধি মেনে চলার কথা বলা হলেও এসব কর্মী এবং খাবার ক্রেতা-বিক্রেতারা ভিড় করতে বাধ্য হচ্ছেন। এমতাবস্থায় নতুন করে রোগ সংক্রমনের আশঙ্কা বাড়ছে।

যা-ই হোক, সরকারী-বেসরকারী সমন্বিত উদ্যোগে প্রশাসন ও জনসাধারণের সহযোগিতায় এ নিম্নমুখী অর্থনীতির এ পরিস্থিতি থেকে উত্তরণ সম্ভব। তবে সদিচ্ছা কথায় সীমাবদ্ধ রেখে বসে থাকলে চলবে না। অতএব, পরিস্থিতি যথাযথভাবে মুল্যায়ন করে কর্মপদ্ধতি স্থির করতে হবে। যেমনঃ

– বিশ্ব স্বাস্থ্য সংস্থার নির্দেশিত নীতিমালা অনুসরণ করতে হবে।

– কুয়ারেন্টিন, সামাজিক দুরত্ব রক্ষা, ভ্রমণ (গমণাগমন) কিংবা লকডাউন নির্দেশনা সঠিকভাবে মেনে চলতে হবে।

– পরিস্কার-পরিচ্ছন্নতা বব্জায় রেখে, পিপিই ব্যবহার করতে হবে। এতে ব্যবহারকারী ও অন্যেরাও কিছুটা সুরক্ষা পাবেন।

– কেউ আক্রান্ত হলে বা রোগীর সস্পর্শে এলে পৃথক করে ১৪ দিন পর্যন্ত পর্যবেক্ষণ করতে হবে।

– রোগনির্ণয় সুযোগ বাড়াতে হবে। টেস্ট-এর ফলাফল যাচাই করে চিকিৎসা ব্যবস্থা দিতে হবে।

– সঠিক তথ্য প্রচার ও প্রসারে উদ্যোগী হতে হবে।

বিশ্বব্যাপী নিম্নমুখী অর্থনীতিকে চাঙ্গা করতে স্বাভাবিক কর্ম-জীবনে ফিরে আসার বিকল্ল নেই, কিন্তু আগুন নিভে গেছে ভেবে অগ্নিযোদ্ধারা তড়িঘড়ি করে ফিরে গেলে ফল যেমন খারাপ হতে পারে, তেমনই সংক্রমণ ঝুঁকি উপেক্ষা করে বেপরোয়াভাবে স্বাভাবিক জীবনে ফিরে এলে নতুন করে কোভিড-১৯ এর বিস্তার অর্থাৎ দ্বিতীয় ঢেউ এর আগমন ঘটতে পারে।

জেনেটিক পরিবর্তনের ফলে করোনাভাইরাসের রোগসৃষ্টির ক্ষমতা কি কমছে?

/0 Comments/in , /by

Interview of Voice of America (VOA) with 

Dr Mustak Ibn Ayub, Department of Genetic Engineering and Biotechnology, University of Dhaka

CARES is committed to giving the society the right information about the COVD -19.  Only scientific discussions by practising scientists from Bangladesh and other places are in CARES website.  Here are some new insightful suggestions from Professor Dr Jeba Seraj, an active member of CARES and a life scientist at Dhaka University. At CARES we talk science.  Engage Science in your life.   –  Wali-ul-Maroof Matin, Chairman, CARES

 

The need for SARS-CoV-2 genome sequencing

/0 Comments/in /by

Professor Sharif Akhteruzzaman, PhD, Department of Genetic Engineering and Biotechnology, University of Dhaka

The ongoing coronavirus pandemic has suddenly and drastically changed the way we lived in the world, only a few months ago. We have not seen such devastation in recent history since World War II. The virus has already killed more than 170,000 people worldwide and billions are at risk of getting infected. There is no drug yet with convincing scientific evidence that can cure the illness, neither is there any effective vaccine in sight. We really don’t know how the crisis is going to end. But we know for sure that the post-pandemic world is never going to be the same as before. Therefore, envisioning a comprehensive strategy to cope with post-pandemic challenges by exploring all scientific means and ways of the 21st century is crucial.

We all know by now that the causative agent of Covid-19 is a novel coronavirus called SARS-CoV-2. Biologically speaking, viruses are not true biological entities and therefore require a host to survive. All viruses carry their genetic information as either DNA or RNA. The SARS-CoV-2 genome is an RNA molecule of about 30,000 bases containing only 15 genes. The human genome, on the other hand, is a double helix DNA—about three billion bases in size and containing about 30,000 genes. RNA is less stable and more prone to mutation than DNA, so RNA viruses generally change and evolve faster. This sometimes allows RNA viruses to jump from one species to another.

Coronavirus did not just pop up very recently. There are hundreds of coronaviruses belonging to a large family of viruses called coronaviridae. They have been around us for a long time in many avian and mammal reservoirs including bats, migratory birds, camels, civets, pangolins, mice, dog and cats. The current trail of death and disease around the world is believed to have been created by at least eight strains of the novel coronavirus.

Since novel coronavirus is a new virus, mining its genome sequence is of crucial importance. Genome sequencing has now become a powerful tool for tracking diseases—this is called “genomic prediction”. Whole genome sequencing will help researchers identify genetic changes that occur in a virus when it spreads through the population. The changes in the genetic sequence of the viral genomes collected from several patients will allow the monitoring of the spread of the disease within the country and between populations over time. It will also provide us with answers to the following questions, which are not known to us at this moment with certainty.

These are—why are some countries suffering more from the virus when compared to other countries? Why do children seem to be less vulnerable than adults? Can the virus evolve into a more virulent strain, and what will happen then? How fast is the coronavirus mutating? How can a vaccine be developed, targeting a particular population? Where did the virus actually originate?

From the perspective of any specific country, including ours, the most important information from the viral genome sequence at this moment will be—identification of particular viral strain/s that are prevalent, identification of infection hotspots or super-spreaders (individuals who spread the infection to more than the expected number of people), and formulation of strategies for public health intervention. This will also help develop a vaccine targeting our own population.

Many countries have already started sequencing the viral genomes collected from patients. In India, three institutes (CSRI, CCMB and IGIB) have started working together on the whole genome sequencing of the novel coronavirus. The government of UK has announced a GBP 20 million investment for mapping the Covid-19 spread in UK through whole genome sequencing. The study will be conducted through a consortium comprised of several research organisations and numerous academic institutes. According to the National Centre for Biotechnology Information (NCBI), there are 818 entries of SARS-CoV-2 complete genome sequence from various countries around the world. Countries that have submitted complete genome sequence include USA, China, Spain, Tunisia, Turkey, Iran, South Africa, Taiwan, Thailand, Vietnam, Nepal and Nigeria, with the highest number of submissions from the US.

From our country, we need to take the initiative to sequence the whole genome of the virus samples collected from infected patients in order to understand more about the virus type, its origin, rate of mutation, what type of vaccine would suit our population and most importantly, how we could face the next wave of infection in case of its re-emergence. In Bangladesh, we have several universities and institutes capable of doing genome sequencing with the necessary expertise. What is important is that we act quickly, before it is too late.

Source:  https://www.thedailystar.net/opinion/news/the-need-sars-cov-2-genome-sequencing-1895359

What Can Antibody Testing Really Tell Us About COVID-19?

/0 Comments/in /by

Compiled by Professor Dr Md. Mozammel Hoq

An immunology expert describes various tests for coronavirus, whether we’re immune to COVID-19 after infection, and more.

ABOUT

Such antibody testing has already started, but it can’t ramp up overnight. And first, scientists need to figure out exactly what to test for, and whether having these antibodies actually make someone immune and for how long, says Yvonne Maldonado, MD, a professor at the Stanford University School of Medicine.

“Right now, we’re trying to do some studies to understand exactly what having antibodies really means,” she says.

A virus-like the new coronavirus, officially called SARS-CoV2, enters cells and hijacks their machinery to make more copies of itself. The immune system then makes antibodies to track down and kill these clones, says Aneesh Mehta, MD, an infectious disease specialist at Emory University School of Medicine in Atlanta.

While diagnostic tests can tell if someone is currently infected, testing for antibodies reveals whether they’ve ever been infected — even if they never felt sick.

Experts say these antibody tests, in the short term, can answer personal questions, like, “Was I infected?” It will take much longer to answer questions such as, “How long will immunity last after infection?” and societal ones, such as, “How dangerous is COVID-19 really?”

And until we know the answer to those questions, we won’t really know the true value of having antibodies. While experts agree it doesn’t mean our lives will completely revert to the way they were before, the tests can help us get on that path.

Knowing how many people were actually exposed and developed antibodies will help officials understand how dangerous it truly is, says Michael Mina, MD, PhD, an assistant professor of epidemiology at the Harvard T.H. Chan School of Public Health. While millions of people worldwide have been diagnosed with COVID-19, many more have probably had it and were unable to get tested or didn’t even notice the infection.

“It really changes our view of many, many things: First and foremost, how many people have been infected and [how many] remain susceptible to this infection,” he says. “But it also changes our view on the actual biology and pathogenicity of this virus. It will determine and change how we’re looking at this virus.”

Antibody tests will also be essential for getting us out of our houses and back to work, and for easing the fear that has paralyzed the country, says Marc Lipsitch, PhD, also an infectious disease epidemiologist at Harvard.

Policymakers will need to know how many people have the disease and how many have immunity against it, Lipsitch says, before deciding when it’s safe to loosen social distancing requirements and when they will need to tighten up again to cope with a new wave of infections.

Hopefully, having antibodies will protect someone from getting COVID-19 a second time. But since the virus has only been around since late last year, no one yet knows how long that protection will last.

With the common cold, a relative of the new coronavirus, immunity doesn’t last long. You can catch it again a few months later. On the other hand, people who contracted severe acute respiratory syndrome (SARS) — another related virus that caused a deadly outbreak in 2003-2004 — still carry protective antibodies more than 15 years later, Maldonado says.

Where this virus lies on that continuum could have a huge impact on the country’s ability to reopen and get people back to work, and also on the development of a vaccine, experts say.

If immunity lasts for years, those who have recovered can generally relax, resume their daily lives, and go back to hugging loved ones.

If immunity lasts for just a short time, then even people who were infected once could be vulnerable again soon — and it will be harder to develop a protective vaccine, says Matthew Sims, MD, PhD, director of infectious disease research at Beaumont Health.

Ramping Up Testing

Researchers are also still deciding which antibodies their tests should look for. Some antibodies are made early in an infection and go away, usually within a few weeks, while others can linger for months or years. Looking for antibodies called Immunoglobulin M, or IgM, can identify recent infections, says Harvard’s Mina.

Immunoglobulin G, or IgG, stays around longer, he says. “I would choose IgG for that effort to get a better understanding of how many people have gotten it,” he says, noting that tests for IgG usually yield information about IgM as well. So far, all of the announced tests look for IgG.

A third antibody, Immunoglobulin A, or IgA, plays a role in the immune function of mucous membranes, Sims says, and will be part of the test he is launching.

ABOUT

There are also different types of tests, Sims says. The commercial tests often use a finger-prick of blood and reveal a “yes/no” answer, like a pregnancy test. Cellex’s test, which takes about 15-20 minutes to yield results, is one of only three that the FDA has approved so far.

Abbott’s test, which is being rolled out on April 16, can be analyzed on any of 2,000 machines that are already in labs across the United States, says a company spokeswoman. Each machine can run 100-200 tests a day at a cost of about $6 each.

Sims says most of these commercial tests just say whether the person has ever been infected, while most of the tests used for research also look for the amounts of antibodies.

The amount would be useful for a few reasons, including finding out if a person’s blood is suitable for donating convalescent plasma, a blood product from someone who has recovered from COVID-19 that can be used to treat people who are fighting the infection and that has antibodies against the virus. For instance, Harvard President Lawrence Bacow, who recently recovered from a COVID-19 infection, donated blood this week in hopes of helping someone who is still fighting it off. In Kentucky, people who are tested for antibodies will be told if they have enough to become donors.

Antibody tests also vary in their reliability, sometimes returning false positives — identifying someone as having had the disease when they haven’t — and false negatives — missing people who have antibodies in their blood.

Maldonado says the test her team has developed at Stanford is reasonably reliable, correctly identifying blood samples with antibodies to the virus the vast majority of the time. Some commercial tests, she says, are not as specific and might find antibodies to the viruses that cause the common cold, for instance, which are similar to the new coronavirus.

Source:  WebMD Health News,  April 16, 2020

Are Easing of Restrictions Possible?

/0 Comments/in , /by

Zeba I. Seraj (PhD), Professor and Chair, Biochem and Mol Biol & Director cBLAST, University of Dhaka

“Lockdowns must be lifted strategically, and not all at once said WHO officials at a briefing on 13 April 2020. However, we should be careful to adopt our own guidelines considering our own unique situation in Bangladesh for gradually coming out of the lockdown. Countries where infection rate has slowed down and the numbers of infection are low can begin easing restrictions, but with care.

It is important to note that social distancing and handwashing and wearing masks even if cloth ones have to become the newer norm. Garment factories can be encouraged to make washable cloth masks for distribution all over the country at a reasonable price. (They may be able to export these too because until a vaccine is out, wearing of masks will have to be the new uniform). So we may need to wear masks for at least another year or two. Pharma companies can start making sanitizing agents for distribution to the whole country. Hospitals, tests and consistent treatments need to be in place in all diagnostic centres, big offices and factories. This can be done with the Rapid test in place which has already been established by the Abott Company in the USA. But our scientists can do this too provided that they are provided with samples. Hospital spaces and ICU units need to be expanded before lockdown is even gradually lifted. Hospitals must also ensure that protective equipment is in place and intensive care beds are on standby.

CARES is committed to giving the society the right information about the COVID -19.  Only scientific discussions by practising scientists from Bangladesh and other places are in CARES website.  Here are some new insightful suggestions from Professor Dr Jeba Seraj, an active member of CARES and a life scientist at Dhaka University. At CARES we talk science.  Engage Science in your life.   –  Wali-ul-Maroof Matin, Chairman, CARES

Coordination and training cells for social distancing and maintaining hygiene to prevent spread have to be present in all Upazilas and thanas. The IT ministry can send training videos to all mobile users.

For Bangladesh, we need to consider how to open gradually with social distancing and hygiene (including surfaces of workplaces). We will need different guidelines for different settings. For townships,

  1. Grocery and other shops. Grocery shops are already open. Other shops can gradually open with strict guidelines in place. In a fixed area, certain shops can remain open on fixed days.
  2. Construction workers and daily laborers and workers in the agricultural sectors. Construction supervisors will need to be trained first. They will need to give daily instructions to construction workers and other daily laborers. Agricultural extension worker need to be trained and then they will in turn need to train the farmers. This is a good time to reign in middlemen. The latter need to be trained on how to remain safe too.
  3. Office staff: they can also start working in shifts or on alternate days.
  4. In case of industries: they need isolation units with a few beds and their own testing facilities. They also need to keep their premises clean.
  5. Separate sets of rules have to be in place for slum areas. Disinfectants and sanitizers need to be provided to this latter category at an ever cheaper rate.

Schools, colleges and Universities can be the last ones to be opened. Meanwhile IT ministry can ensure Wi-Fi services all over the country for establishment of online classes and quizzes.

According to WHO, countries easing lockdowns should meet the following criteria:

1. The transmission is controlled.

2. Health system capacities are in place to detect, test, isolate and treat every COVID-19 case and trace every contact.

i. Tests need to be expanded quite a lot. Many university departments have the necessary machines but may need the kits.

ii. A database needs to be established for coordination of the detection and testing. CDC has given the green signal to use of saliva as a proper sample to detect Covid 19. The latter is much easier and less prone to splashing of virus-contaminated aerosols. The rapid test based on an isothermal test needs to be established. Our scientists have the capacity do this.

iii. Apps for contact tracing need to be established. And research on back-tracing of persons coming into Bangladesh from the middle of January needs to be done.

iv. Relevant scientists need to be provided with samples from different regions of Bangladesh for sequencing. Since this virus mutates a lot, its sequence will need to be known in order to determine whether any vaccine will be effective.

3.  Outbreak risks are minimized in special settings like health facilities and nursing homes.

4.  Preventive measures are in place in workplaces, schools and other places where it’s essential for people to go.

5.  Importation risks can be managed. Airports need to be controlled by the Army. All passengers kept aside until tested to be free of virus. Rapid tests need to be in place and all tested before being allowed into the community.

6.  Communities are fully educated, engaged and empowered to adjust to the “new norm”.

WHO advice is: Countries seeing their numbers stabilize should not believe the worst is over. Measures such as physical distancing and handwashing will need to stay in place even after lockdowns are lifted. “We are going to have to change our behaviors for the foreseeable future, says a WHO official. Increased capacity at health systems will also need to be maintained once restrictions are eased. “As we come out of these lockdown situations, we may see a jump back up of cases. And we don’t want to lurch from lockdown to nothing. So now is the time to be very, very careful.”

Covid-19: Taming the beast

/0 Comments/in , /by

Professor Ahmed Abdullah Azad PhD, Secretary General, Islamic-World Academy of Sciences

The Covid-19 pandemic, caused by coronavirus SARS-CoV-2, has brought the entire world to its knees and virtually stopped all face-to-face social interactions between humans. Personal freedoms and human rights have been severely curtailed all over the world to help slow down the infection and death rates. This newly discovered coronavirus is extremely contagious, and up to 20 times more deadly than seasonal flu. Currently, the only way to reduce community spread is by maintaining good hygiene, social distance and self-isolation. In Bangladesh, it will be a challenge to implement these public health measures in congested environments, and particularly hard for disadvantaged people and casual workers who would starve if confined at home for long. A substantial portion of the government’s stimulation package must be ring-fenced for the poor and needy, otherwise the public health measures will fail.

Effective health and economic policies to counter the adverse effects of the pandemic require extensive testing for the presence of the virus in infected individuals, and people they have been in contact with. PCR- and sequence-based tests require expensive equipment and reagents, are time-consuming, and the total capacity is hardly adequate for testing all infected individuals, contact tracing and determining the infection status of health care workers. There is an urgent need for a quick, inexpensive and less-invasive blood tests for detecting anti-viral antibodies and confirming infection. A simple dot-blot blood test that provides results within 15 minutes has reportedly been developed through a joint venture collaboration between Gonoshasthaya Kendra and RNA Biotech Ltd, a company formed by a group of young researchers in Bangladesh.

If the claims for this locally developed test are validated, then the project should be treated and supported as an urgent national priority, so that adequate numbers of kits can be made available for extensive testing at the earliest. The quoted price per test is miniscule in comparison to the gene-based assays currently in use in Bangladesh and could be much lower if the recombinant antigens (the four structural proteins of the virus) were produced in Bangladesh. The imported recombinant viral antigens, produced in bacteria (E.coli), might suffice for virus detection but may not be ideal for further biological and clinical studies.

CARES is committed to giving the society the right information about the COVID -19.  Only scientific discussions by practising scientists from Bangladesh and other places are in CARES website.  Here are some new insightful suggestions from Professor Dr Jeba Seraj, an active member of CARES and a life scientist at Dhaka University. At CARES we talk science.  Engage Science in your life.   –  Wali-ul-Maroof Matin, Chairman, CARES

The above rapid test, using locally-produced recombinant antigens that more closely resemble those in the virus particle, could also be an important research tool for following antibody production and response during different phases of disease progression. If properly designed, the dot-blot assay could help identify virus-neutralising antibody in blood collected from individuals recovered from the infection. If the neutralising antibody could be purified, then its protein sequence could be reverse-engineered into a therapeutic monoclonal antibody for mass production by recombinant DNA technology. The required expertise is present in Bangladesh but the multidisciplinary technologies need to be assembled under one roof as a national core facility, a plea that has fallen on deaf ears.

It is not enough to just keep the virus at bay by social isolation. The virus-induced paralysis of normal life and enforced shutdown cannot continue ad infinitum, and countermeasures need to be contemplated. To tame and conquer the invisible beast, we need to understand its biology and molecular structure to discover its soft underbelly as a target for drug and vaccine development. Coronaviruses of innumerable types are ubiquitous in many non-primate animals. Seven of these have managed to cross over into humans. Four have been around for over a century, and cause about a third of all the seasonal colds. Three that have emerged in recent years (SARS, MERS and Covid-19) cause severe illness in humans, termed Acute Respiratory Distress Syndrome (ARDS), but SARS-CoV-2 (Covid-19 virus) is by far the most deadly and contagious.

So, how did SARS-CoV-2 emerge in humans and why is it so dangerous? The ancestor could be a bat coronavirus (88 percent sequence homology) that cannot produce disease in humans or spread from one human to another. It could have picked up these properties through genetic exchange with another coronavirus in a co-infected intermediate host such as a pangolin (an ant-eating mammal), which is a culinary delicacy and is used in Chinese medicine. It is possible that the Covid-19 virus that had finally evolved into a dangerous pathogen in pangolins passed over into a human in the wet markets of Wuhan. SARS-CoV-2 can enter human cells and spread to other humans through a molecular interplay between the viral spike protein on its surface (that gives all coronaviruses the spectacular crown-like appearance) and two vital enzymes on the surface of human cells.

The spike protein of the SARS-CoV-2 virus contains two distinct structural units. A receptor-binding domain uses a human enzyme—angiotensin converting enzyme 2 (ACE 2),as a receptor to attach the virus to the human cell surface. A second membrane-binding domain, after specific cleavage by the human enzyme Furin, can interact with and fuse the virus and cell membranes, thus facilitating virus entry into epithelial cells, and then into lung cells.This leads to infection of both the upper and lower respiratory tracts (lungs) causing ARDS, which is characterised by serious breathlessness, breakdown of cell signalling networks (cytokine storm), self-destructive immune response and massive secondary infections, ultimately leading to multiple organ failure, especially in older people with co-morbidities such as heart disease, hypertension, diabetes, kidney disease and immunodeficiencies. Less virulent and less contagious human coronaviruses either do not contain the Furin-cleavage site or possess a partial Furin-cleavage site.

Two therapeutic approaches can be tried to stop SARS-CoV-2 from infecting humans. One is to prevent or disrupt the interaction between ACE 2 and the receptor-binding domain of the viral spike protein. The other is to prevent Furin from cleaving the viral spike protein. While required expertise and facilities in structural biology and rational drug design may not be currently available, scientists in Bangladesh can target the above drug development opportunities by using expertise and resources already available to them. Molecular and cell biologists should be able to develop very specific bioassays based on the above molecular targets, and these disease-specific bioassays could be used to screen the very large libraries of indigenous medicinal plants, and isolated secondary metabolites, collected by ethnobiologists and medicinal chemists in Bangladesh. Every positive lead compound would be a potential candidate drug against SARS-CoV-2 that could be patented and developed into a new drug if the required technology platform is established as a national core facility, another plea that has gone unheeded over the last fifteen years. Hopefully, the Covid-19 pandemic will open the eyes and ears of our policymakers so that higher education, research and innovation are supported at the required levels, so that we are prepared the next time around.

Besides coronaviruses, a number of viruses have crossed over from wild animals to humans (Influenza, HIV, Ebola, Marburg) in recent years, causing very frightful diseases. Most of them have lived in animal hosts for thousands of years but in recent times, human activities have destroyed the natural habitats of their hosts and brought man and wild animals into close contact. The Covid-19 pandemic is a timely warning to the human race to not destroy the environment and natural habitats of exotic animals in the mad pursuit of profits and development at any cost.

Prof Ahmed Azad PhD, a retired molecular virologist, has been intimately involved in developing several anti-viral drugs and vaccines. After retirement (2006), he has worked with younger colleagues to help build biotechnology research capacity in Bangladesh. Email: aaazad1945@gmail.com

The writer is a founding member of CARES.

Source:  https://www.thedailystar.net/opinion/news/covid-19-taming-the-beast-1892629

কোভিড-নাইন্টিন রোগনির্ণয়ের সুবিধা-অসুবিধা

/0 Comments/in , /by

মোহাম্মদ আশরাফ হোসেন, ফেলো হিসেবে US FDA তে ৮ বছর কর্মরত ছিলেন, ফ্লোরিডা, ইউএসএ

বিধানচন্দ্র রায় ছিলেন একাধারে বিশিষ্ট চিকিৎসক, শিক্ষাগুরু এবং পশ্চিমবঙ্গের মুখ্যমন্ত্রী যিনি ভারতরত্ন উপাধিলাভ করেছিলেন। কথিত আছে যে, কথোপকথন কিংবা পরীক্ষা-নিরীক্ষা ছাড়াই শুধু রোগীকে পর্যবেক্ষণ করেই তিনি সঠিকভাবে রোগনির্ণয় ও চিকিৎসা করতে পারতেন। বাস্তবে এমনটি খুব কমই ঘটে। সঠিকভাবে চিকিৎসা করতে রোগনির্ণয় অত্যাবশ্যক, আর সেজন্য পদ্ধতিগত সাক্ষাৎকার ছাড়াও প্রয়োজন হয় শারীরিক পরীক্ষা ও নানান ধরণের ল্যাবোরেটরী টেস্ট-এর। প্রযুক্তির অগ্রযাত্রা আর চিকিৎসা পারস্পরিক সম্পর্কিত; ডায়াগনস্টিক মেডিক্যাল ডিভাইসের মাধ্যমে এখন সাধারণ থেকে বিরল রোগ নির্ণয় করে অনতিবিলম্বে চিকিৎসা ব্যবস্থা করা অনেক সহজ হয়েছে। এর ফলে রোগ-ভোগ, জটিলতা সৃষ্টি, হাসপাতালে ভর্তি, অপারেশন ও চিকিৎসা ব্যয় সীমিতকরণের সুযোগ তৈরি হয়েছে।

অদৃশ্য শত্রু করোনাভাইরাসের সংক্রমণ থেকে কোভিড-১৯ রোগ গত তিন মাসে বিশ্বে ছড়িয়ে পড়েছে। রোগ উপসর্গের অনুপস্থিতি কিংবা লক্ষণ রোগভিত্তিক না হওয়ায় পরীক্ষা-নিরীক্ষা ছাড়া শ্বাসতন্ত্রের এ রোগ নিরূপণ করা কঠিন। অথচ এ রোগে এ যাবৎ আক্রান্ত হয়েছে ১৮ লক্ষাধিক মানবসন্তান, আর মাত্র কয়েক মাসে মৃত্যু হয়েছে ১.১ লক্ষাধিক। বিজ্ঞান-প্রযুক্তিতে অগ্রগামী, শিল্পোন্নত দেশ যুক্তরাষ্ট্রেও কোভিড-১৯ রোগ বিস্তৃত হয়েছে ব্যাপকভাবে; এ যাবৎ আক্রান্ত হয়েছে ৫.৩ লক্ষাধিক, আর মৃত্যু হয়েছে ২০.৫ সহস্রাধিক। বিশ্বব্যাপী মৃত্যুর মিছিলে শত-সহস্র যোগ হচ্ছে প্রতিদিন।

যুক্তরাষ্ট্রের প্রধান জনস্বাস্থ্য প্রতিষ্ঠান (Center for Disease Control & Prevention) সিডিসি-র নির্দেশনামতে সন্দেহভাজন সবার করোনাভাইরাসের সংক্রমণ টেস্টিং-এর প্রয়োজন নেই; শুধুমাত্র রাজ্য ও স্থানীয় স্বাস্থ্য বিভাগের নির্দেশ মেনে টেস্টিং সুপারিশ করতে পারেন সংশ্লিষ্ট চিকিৎসক। সিডিসি’র নির্দেশনা ও ফুড অ্যান্ড ড্রাগ অ্যাডমিনিস্ট্রেশন (এফডিএ) -এর সাময়িক [ত্বরান্বিত প্রক্রিয়ায়] অনুমোদন-ক্রমে কোভিড-১৯ সনাক্ত করতে কয়েক ডজন নতুন নিউক্লেয়িক এসিড-ভিত্তিক আরটি-পিসিআর ও সেরোলজি্ক্যাল টেস্ট-এর ব্যবহার শুরু হয়েছে।

আরটি-পিসিআর অ্ত্যাধুনিক মোলিকুলার বায়োলোজী প্রযুক্তি যা থার্মাল সাইক্লার ও ইলেক্ট্রফোরেসিস যন্ত্রের মাধ্যমে সম্পাদন করা হয়। শ্বাসতন্ত্র [যেমন নাসাপথ] থেকে সংগৃহিত নমুনা থেকে করোনাভাইরাসের অস্তিত্ব  সনাক্ত করা সম্ভব।  আর সেরোলজি্ক্যাল টেস্ট-এর মাধ্যমে রক্তের জলীয় অংশে উপস্থিত অ্যান্টিবডি (অর্থাৎ, করোনাভাইরাস অ্যান্টিজেন/আমিষের প্রতিরোধী আমিষ) সনাক্ত করা হয়। শুধুমাত্র প্রশিক্ষিত স্বাস্থ্যকর্মীরাই সঠিকভাবে নমুনা সংগ্রহ, সংরক্ষণ, স্থানান্তর ও পিসিআর টেস্ট  পরিচালনা করতে পারেন।  এছাড়া ল্যাবোরেটরির গঠন ও সক্ষমতাও অত্যাবশ্যক। যুক্তরাষ্ট্রে ক্লিনিক্যাল ল্যাবোরেটরির গ্রহণযোগ্যতা যাচাই করা হয় প্রাতিষ্ঠানিক (যেমন, CLIA) Certification -এর মাধ্যমে।

অত্যাধুনিক প্রযুক্তি ব্যবহার করে এসব টেস্ট থেকে গুণগত (অর্থাৎ, পযিটিভ বা নেগেটিভ) ফলাফল পাওয়া গেলেও এদের কার্যকারিতা শতভাগ নিশ্চিত নয়। সাধারণভাবে, ইলেক্ট্রফোরেসিস-এর মাধ্যমে সঠিক আকারের ডিএনএ ব্যান্ড দৃশ্যমান হলে তা কাঙ্ক্ষিত ডিএনএ অর্থাৎ টেস্ট পযিটিভ, অন্যথায় তা নেগেটিভ। একইভাবে, রোগীর দেহে পরিমিত পরিমাণে অ্যান্টিবডি (কিংবা করোনাভাইরাস অ্যান্টিজেন) থাকলে এবং যথাযথভাবে পরীক্ষা করলে টেস্ট পযিটিভ হতে পারে, কিন্তু গঠনে মিল থাকায় রক্তে কোভিড-১৯ সৃষ্টিকারী করোনাভাইরাস না থাকলেও HKU-1, NL-63, OC-43 বা L229E ভাইরাস-এর কারণে টেস্ট পযিটিভ হতে পারে। আবার রোগীর দেহে পরিমিত পরিমাণে অ্যান্টিবডি (কিংবা করোনাভাইরাস অ্যান্টিজেন) না থাকলে তা নেগেটিভ হতে পারে। ত্রূটিপূর্ণ নমুনা সংগ্রহ, তাপমাত্রা-রক্ষায় ব্যর্থতা, নমুনা-মিশ্রণ কিংবা প্রক্রিয়াগত ত্রূটির কারণে বিভ্রান্তিকর ফল পাওয়া যেতে পারে। অতএব, এসব টেস্টের কার্যকারিতা বা সংবেদনশীলতা (সেন্সিটিভিটি) প্রতিষ্ঠিত হতে সত্য/ মিথ্যা পযিটিভ ও নেগেটিভ তথ্য-উপাত্ত সংগ্রহে অভিজ্ঞতা ও সময়ের প্রয়োজন।  তুরুটি

করোনাভাইরাস টেস্টের ফলাফল বিচার ও পরবর্তী করণীয় নির্ধারণ করতে বিশেষ সাবধানতা অবলম্বন করা প্রয়োজন। সাধারণভাবে পিসিআর টেস্ট পযিটিভ সংক্রমণ নির্দেশক হলেও অ্যান্টিবডি টেস্ট পযিটিভ চলমান সংক্রমণ নির্দেশক না-ও হতে পারে; বরং তা ব্যক্তির রোগ প্রতিরোধক্ষমতা (যা আপেক্ষিক) ইঙ্গিত করে। যেমন, টিউবারকুলিন টেস্ট পযিটিভ হলে সাধারণতঃ তা অতীত যক্ষা সংক্রমণ বা বিসিজি টিকার কার্যকারিতা ইঙ্গিত করে। অপরপক্ষে, করোনা ভাইরাস টেস্টের ফল নেগেটিভ হলে ব্যক্তি রোগমুক্ত কিংবা ঝূকিমুক্ত, এমন দাবী করাও অসঙ্গত। বরং মিথ্যা-নেগেটিভ একজন বাহক মিথ্যা স্বস্তি নিয়ে অন্যদের সান্নিধ্যে এসে অজান্তেই কোভিড-১৯ রোগ বিস্তারে সহায়তা করতে পারেন।

সম্প্রতি জার্মানীর গটিংগেন ইউনিভার্সিটির দুই গবেষক Lancet ID Journal-এ প্রকাশ করেছেন যে বিশ্ব জুড়ে আক্রান্তের সংখ্যা ১ কোটি ছাড়ালেও এ যাবৎ প্রায় ৬% কোভিড-১৯ রোগ সনাক্ত হয়েছে <https://www.uni-goettingen.de/en/606540.html>। তাদের মতে শিল্পোন্নত দেশগুলিতেও গ্রহণযোগ্য পদ্ধতির অভাব, অপর্যাপ্ত কিংবা বিলম্বিত টেস্টিং ইত্যাদি কারণে সারা বিশ্বে ইটালীতে ৩.৫% আর যুক্তরাজ্য, স্পেন ও যুক্তরাষ্ট্রে যথাক্রমে <১.২%, <১.৬% ও <১.৭% সনাক্তকরণ সম্ভব হয়েছে।  কোভিড-১৯ রোগ নির্ণয়ে আজ নানাবিধ বিড়ম্বনার মুখোমুখি চিকিৎসক ও স্বাস্থসেবা প্রদানকারী ব্যক্তিবর্গ, তারই ইঙ্গিত এ লেখায়। জার্নালটি চিকিতসা গবেষকদের কাছে অত্যন্ত মূল্যবান হলেও উল্লিখিত রিপোর্ট বিশ্বাস করতে যেন কষ্ট হয়।

তবে আশার কথা, রোগতত্ত্ববিদেরা মনে করছেন, শিগগিরই করোনাভাইরাস সংক্রমণ- তথা মৃত্যুহার কমে যাবে।

 

COVID-19 infection: Origin, transmission, and characteristics of human coronaviruses

/0 Comments/in , /by

Author links open overlay panel Muhammad AdnanShereenab1, SulimanKhana1, AbeerKazmic, NadiaBashira, RabeeaSiddiquea

Abstract

The coronavirus disease 19 (COVID-19) is a highly transmittable and pathogenic viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARSCoV- 2), which emerged in Wuhan, China and spread around the world.  Genomic analysis revealed that SARS-CoV-2 is phylogenetically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be the possible primary reservoir. The intermediate source of origin and transfer to humans is not known, however, the rapid human to human transfer has been confirmed widely. There is no clinically approved antiviral drug or vaccine available to be used against COVID-19. However, few broad-spectrum antiviral drugs have been evaluated against COVID-19 in clinical trials, resulted in clinical recovery. In the current review, we summarize and comparatively analyze the emergence and pathogenicity of COVID-19 infection and previous human coronaviruses severe acute respiratory syndrome coronavirus (SARS-CoV) and middle east respiratory syndrome coronavirus (MERS-CoV). We also discuss the approaches for developing effective vaccines and therapeutic combinations to cope with this viral outbreak. … READ MORE

Coronavirus and Pneumonia

/0 Comments/in , /by

(Compiled by Dr. Md. Mozammel Hoq)

Most people who get COVID-19 have mild or moderate symptoms like coughing, a fever, and shortness of breath. But some who catch the new coronavirus get severe pneumonia in both lungs. COVID-19 pneumonia is a serious illness that can be deadly.

What Is Pneumonia?

Pneumonia is a lung infection that causes inflammation in the tiny air sacs inside your lungs. They may fill up with so much fluid and pus that it’s hard to breathe. You may have severe shortness of breath, a cough, a fever, chest pain, chills, or fatigue.

Your doctor might recommend cough medicine and pain relievers that reduce fever. In the most serious cases, you may need to go to the hospital for help breathing with a machine called a ventilator.

You can get pneumonia as a complication of viral infections such as COVID-19 or the flu, or even a common cold. But bacteria, fungi, and other microorganisms can also cause it.

What is novel coronavirus-infected pneumonia?

The illness tied to the new coronavirus was originally called novel coronavirus-infected pneumonia (NCIP). The World Health Organization renamed it COVID-19, which is short for coronavirus disease in 2019.

COVID-19 Pneumonia Symptoms

A fever, a dry cough, and fatigue are common early signs of COVID-19. You may also have nausea, diarrhea, muscle aches, and vomiting.

If your COVID-19 infection starts to cause pneumonia, you may notice things like:

  • Rapid heartbeat
  • Shortness of breath or breathlessness
  • Rapid breathing
  • Dizziness
  • Heavy sweating

How Many People With COVID-19 Will Get Pneumonia?

About 15% of COVID-19 cases are severe. That means they may need to be treated with oxygen in a hospital. About 5% of people have critical infections and need a ventilator.

People who get pneumonia may also have a condition called acute respiratory distress syndrome (ARDS). It’s a disease that comes on quickly and causes breathing problems.

The new coronavirus causes severe inflammation in your lungs. It damages the cells and tissue that line the air sacs in your lungs. These sacs are where the oxygen you breathe is processed and delivered to your blood. The damage causes tissue to break off and clog your lungs. The walls of the sacs can thicken, making it very hard for you to breathe.

Who’s Most Likely to Get It?

Anyone can get COVID-19 pneumonia, but it’s more likely in people who are 65 or older. Those who are 85 or older are at the highest risk.

People who live in nursing homes or who have other health problems like these also have higher chances of more severe illness with COVID-19:

  • Moderate to severe asthma
  • Lung disease
  • High blood pressure
  • Heart disease
  • Diabetes
  • Liver disease
  • Renal failure
  • Severe obesity, or a body mass index (BMI) of 40 or higher

Someone who has a weakened immune system may be more likely to get severe COVID-19 illness, too. This includes smokers, people being treated for cancer, people who have had a bone marrow transplant, people who have HIV or AIDS that’s not under control, and anyone who takes medications that slow the immune system, like steroids.

How Is COVID-19 Pneumonia Diagnosed?

Your doctor can diagnose COVID-19 pneumonia based on your symptoms and lab test results.

Blood tests may also show signs of COVID-19 pneumonia. These include low lymphocytes and elevated C-reactive protein (CRP). Your blood may also be low in oxygen. A chest CT scan may show patchy areas of damage in both your lungs. Doctors call this “ground glass.”

Are There Treatments for COVID-19 Pneumonia?

Pneumonia may need treatment in a hospital with oxygen, a ventilator to help you breathe, and intravenous (IV) fluids to prevent dehydration.

Clinical trials are looking into whether some experimental drugs and treatments used for other conditions might treat severe COVID-19 or related pneumonia:

  • Antivirals, including remdesivir, which the FDA hasn’t approved but which was developed to treat the Ebola virus

The malaria drugs chloroquine and hydroxychloroquine, sometimes along with azithromycin, an antibiotic

COVID-19 Pneumonia Prevention

If you’re in a high-risk group for COVID-19 pneumonia, take these steps to prevent infection:

  • Wash your hands often. Scrub with soap and water for at least 20 seconds.
  • If you can’t wash your hands, use a hand sanitizer gel that’s at least 60% alcohol. Rub it all over your hands until they’re dry.
  • Try not to touch your face, mouth, or eyes until you’ve washed your hands.
  • Avoid anyone who’s sick. Stay home and avoid others as much as you can.
  • Regularly clean and disinfect surfaces in your home that you touch often, such as countertops and keyboards.

The pneumonia vaccine protects against a kind of bacteria, not the coronavirus. But it can support your overall health, especially if you’re older or have a weak immune system. Talk to your doctor about whether you should get it.