Month: March 2020

On World Tuberculosis Day (March 24, 2020), I interviewed Priyadharshini M V, project assistant in Mycobacterium Diseases in Animal Network (MyDAN) lab at Tamil Nadu Veterinary and Animal Sciences University (TANUVAS), Chennai. She holds an M.Tech in Biotechnology and worked as a medical geneticist in Centre for Medical Genetics, Chennai, prior to her work at TANUVAS. In this interview, she elaborates on TB, the challenges and mitigation strategies in India, and how the general public can contribute to the fight to eradicate TB. 

 

Left: Priyadharshini M V. Right: A depiction of Mycobacterium tuberculosis in a patient’s lung. Picture retrieved from livescience.com

Could you please tell a little bit about TB and how badly India is affected by TB?

TB is an airborne disease caused by the bacterium Mycobacterium tuberculosis (Mtb). It is the leading cause of death from an infectious disease worldwide and claims about 3 lives every minute. TB is curable and preventable. The bacteria usually attack the lungs (pulmonary TB) but can also attack other parts of the body like the kidney, spine, and brain.

Not everyone infected with TB bacteria becomes sick. So, there are two TB-related conditions: latent TB infection (LTBI) and TB disease (active TB). Many people who have latent TB infection never develop TB disease, but there are a few exceptions. If it is not treated properly, TB can be fatal. There are also the multidrug-resistant (MDR) and extensively drug-resistant (XDR) forms of TB that occur, but they are still rare.

India accounts for about a quarter of the global TB burden. Worldwide, India is the country with the highest burden of TB – both TB and MDR TB. There are an estimated 79,000 multi-drug resistant TB patients among the notified cases of pulmonary TB each year. India is also the country with the second-highest number (after South Africa) of estimated HIV associated TB cases.

How does a person get infected with TB? What are the symptoms of the disease?

The TB bacteria are introduced into the air when a person with TB disease of the lungs or throat coughs, sneezes, speaks, or sings. People nearby may breathe in these bacteria and become infected.

TB disease in the lungs may cause symptoms like a bad cough that lasts 3 weeks or longer, pain in the chest, coughing up blood or sputum (phlegm from deep inside the lungs). There are also other symptoms like weakness or fatigue, weight loss, loss of appetite, chills, fever, sweating at night.

Could you describe some measures taken by the government to curb this disease?

The Government of India aims to eliminate TB by 2025. This was announced by Shri J P Nadda, Union Minister of Health and Family Welfare, in March 2017. For this, a lot of things set out in the National Strategic Plan 2017 – 2025 needs to be done.

According to the World Health Organisation (WHO), the elimination of TB means that there should be less than one case of TB for a population of one million people. TB treatment and care in India is provided in the public sector by the government’s Revised National TB Control Programme (RNTCP), which is responsible for implementing the government’s five-year plans to combat TB. India’s remarkable achievements in TB control in the last ten years include testing more than 80 million people, detecting and treating 15 million TB patients, and saving millions of lives as a result of the efforts of the RNTCP.

What are some of the plans in this new strategy of the government?

The financial resources for TB control for 2017-2025 are doubled, the diagnostic tool CB-NAAT is to be rolled out across the country, and the two drugs Bedaquiline and Delamanid are also scheduled for a broader rollout. First and second-line drug susceptibility testing is in use or at least on the agenda. Also, patients with TB are tested for HIV and patients with HIV are tested for TB. Drug treatment is moving from intermittent therapy to daily fixed-dose combinations.

 

Why, in your opinion, has the battle against TB in India been difficult?

India’s progress against the disease has not been consistent. As per WHO reports, it has been a persisting problem in developed countries. People infected with HIV are 19 times more likely to develop active TB. The risk of active TB is also greater in people suffering from conditions that impair their immune system. Malnourished or undernourished people are 3 times more likely to contract TB when compared to the others. So, it’s pretty obvious that India, being a third world country with two-third of its population in poverty and having the third-largest population suffering from AIDS, has been struggling to combat and eradicate TB. Shortage of resources and research is another big limitation.

How can the general public contribute to the fight against TB?

There are two important things one can do to contribute to the fight against TB: One is to create awareness about the disease and the other is to get the people who fall in the high-risk group to test for TB. People with HIV infection, people who were infected with TB bacteria in the last 2 years, babies, young children, people who inject illegal drugs, people who are sick with other diseases that weaken the immune system, people who were not treated correctly for TB in the past, and the elderly are at high risk of developing TB disease.

People who anticipate repeated or prolonged exposure or an extended stay over a period of the year may undergo annual testing. Additional preventive measures could include using personal respiratory protective devices. Tuberculosis germs don’t thrive on surfaces. You can’t get the disease from shaking hands with someone who has it or by sharing their food or drink.

If one has latent TB, he/she must take all of his/her medication, so he/she doesn’t develop active TB, which is contagious. People with active TB must limit their contact with other people at work, school, or home. They must cover their mouth when they laugh, sneeze, or cough and wear a surgical mask when they’re around other people during the first weeks of treatment.

People travelling to a place where TB is common must avoid getting close to or spending a lot of time in crowded places with people who have TB. Children in countries where TB is common should get the BCG vaccine.

Side and top views of the structure of a protein – S protein – of 2019-nCoV.          Retrieved from the paper by Wrapp and others published in the journal Science.

With new COVID-19 cases being reported in India, there has been a deluge of information – news stories, articles and awareness campaigns – around it. Containment, social distancing, transmission, flattening the curve, epidemic, and pandemic are some terms that you will now find in most articles. In this short post, I try to explain some of these terms.

COVID-19, SARS-CoV-2, 2019-nCOV: COVID-19 (Coronavirus Disease) is an infectious disease caused by the most recently discovered coronavirus. Coronaviruses are a family of viruses that have RNA as their genetic material. Other viruses of this family include MERS (Middle East Respiratory Syndrome coronavirus), SARS (Severe Acute Respiratory Syndrome coronavirus) and viruses that cause common cold (E.g. Rhinoviruses). The new coronavirus was initially called 2019-nCOV (2019 novel coronavirus) when it was first identified in China. The virus is now named SARS-CoV-2 (Severe Acute Respiratory Syndrome coronavirus 2). WHO announced the name of the new coronavirus disease as COVID-19 on February 11, 2020.

Endemic: A disease, or an infectious agent that causes it, is called an endemic when it is usually present in or is restricted to a community in a certain geographical area. For example, Kyasanur Forest Disease (KFD), commonly known as monkey fever is a viral disease endemic to South India. This is a disease seen in specific areas in South India. KFD is an endemic prevalent in Shimoga district of Karnataka.

Epidemic: When the number of disease cases is in excess than the normally expected numbers, then the disease is called an epidemic. The numbers of normally expected cases are defined specifically for each case. When the number or density of susceptible cases exceed a threshold (called an epidemic threshold), the event is defined as an epidemic.

Outbreak: When the disease cases that occur are more than what is normally expected, it is called an outbreak. For example, there were two outbreaks of Nipah in Kerala (2018 and 2019). Although epidemic and outbreak have overlapping definitions, an outbreak can be seen as the process of occurrence of an epidemic.

Pandemic: When a disease epidemic spreads across a continent or worldwide, it is called a pandemic. WHO characterized COVID-19 as a pandemic on March 11, 2020.

Infected person: A person who has the infectious agent, which causes the disease, in his body.

Incubation period: This is the time in which the infectious agent (say, a virus) is present in the host (an infected person), but the person has no symptoms. The incubation period for COVID-19 is 14 days or less. According to a study, the average incubation time for COVID-19 is 5.5 days. Less than 2.5% of the cases develop symptoms in 2.2 days and 97.5% of the cases develop symptoms in 11.5 days. Only 1 in 10,000 cases developed symptoms after 14 days.

Convalescent period: This is the time when an infected person recovers from the illness.

Transmission: The way in which a disease spreads from one person to another is called transmission. If the disease is transmitted from an infected person to a healthy person, it is called contact transmission. Contact transmission can be direct – when there is physical contact between the infected person and the healthy person, or indirect – where the infectious agent spreads by indirect means without direct physical contact. Indirect transmission can include droplet transmission or transmission by fomites.

Droplet Transmission: When an infectious agent (say, a virus) is transmitted through respiratory droplets that are propelled into the air by sneezing or coughing, it is called droplet transmission. When an infected person coughs or sneezes, droplets of moisture of different sizes contaminated with infectious agents are propelled out in the air. When these droplets contact the eyes, nose or mouth of a healthy person, he/she can get infected. Droplets are usually heavier and settle down to the ground quickly because of gravity. These droplets can be propelled to about 1 metre depending on the size of the particle and the force with which it is expelled.

Aerosol Transmission: When an infectious agent (say, a virus) is transmitted through aerosols (suspension of fine particles in the air) propelled into the air by sneezing or coughing, it is called aerosol transmission. When an infected person coughs or sneezes, aerosols of moisture of different sizes contaminated with infectious agents are propelled out in the air. Aerosols are lighter and can remain in the air for sometime before it falls. They can be propelled up to 3 metres depending on the size of the particle and the force with which it is expelled. SARS-CoV-2 is reported to be stable in aerosols for 3 hours.

Transmission by Fomites: Fomites are non-living objects that can be contaminated with infectious agents and can transmit the disease. These include water, plastics, metals – doorknobs, keyboards, phones, handrails etc. If an infected person sneezes or coughs and the droplets fall on fomites, the infectious agents can remain active on fomites for hours or days. When a healthy person touches an infected surface and then touches his/her nose, eyes or mouth, the infectious agent can get inside the body. A recent study has shown that SARS-CoV-2 can be viable for 3 hours in aerosols, and up to 3 days on stainless steel, copper and cardboard surfaces.

Local Transmission: When the source of infection is present with a locality, there is local transmission of the disease. That means if a person in Bangalore gets infected by someone who is in Bangalore, then there is a local transmission. This is referred to as stage II of the epidemic.

Community Transmission: When one cannot relate confirmed cases by chains of transmission (i.e., when one cannot trace the source of infection of all the different people in the chain) for a large number of cases, then it is called community transmission. In other words, if a person who has not come in contact with anyone known to be infected and has not travelled to any country when the virus is spreading tests positive, then there is community transmission. This is referred to as stage III of the epidemic.

Social distancing: It is the practice of maintaining more than the usual physical distance from other people. The purpose is to stop or slow down the spread of a disease that can be transmitted by physical contact, droplets, or fomites. The more distance you maintain from people, the lesser the risk of getting the disease.  

Flattening the curve:  This is a term used to indicate preventing a sharp peak of infections. During an epidemic, the disease spreads quickly as infected people come in contact with healthy people, who in turn come in contact with more people. Let us say there is one infected person (the person may or may not have developed symptoms). He/She hangs out with 3-4 friends. There is a possibility that these 3-4 people are now infected. These people now meet with more people, who in turn meet other people. Suddenly there is a sharp increase in the number of cases when all of these people develop symptoms within a few days. This overwhelms the healthcare system. If people practise social distancing, the chances of infection are lesser and, therefore, the sharp peak can be flattened as lesser cases are present in a given time. This can reduce the burden on the healthcare system.

Quarantine: The process of isolating people who have been exposed to an infection that can spread. The aim of quarantining is to contain – prevent the further spread of – the disease. Quarantine for 14 days is recommended for suspected COVID-19 cases.

Herd immunity: This is indirect protection for susceptible people in a community. In an outbreak, if a large proportion has become immune to the infection, they indirectly protect people who are not immune to the infection by disrupting the spread. Consider the situation with COVID-19. Let us say healthy people get infected. They become sick, isolate themselves (especially from people who are at higher risk of death by infection because of other health conditions) and eventually recover. When the number of recovered people increases in a population, they indirectly protect those who have not been infected as the chain can now be broken quickly.

Covidiot (informal use): This term is used to refer to a person who ignores the warnings regarding public health or safety and hoards goods denying them from their neighbours during the COVID-19 pandemic.

Sources:

https://www.cdc.gov/csels/dsepd/ss1978/glossary.html

https://www.who.int/emergencies/diseases/novel-coronavirus-2019