|CONCEPT AND ISSUE
|Year : 2020 | Volume
| Issue : 2 | Page : 110-116
Pandemics and epidemics: Past to present
Remiya Mohan, Vandna Pandey
Lecturer, College of Nursing, AIIMS, Jodhpur, Rajasthan, India
|Date of Submission||07-Jul-2020|
|Date of Decision||29-Oct-2020|
|Date of Acceptance||15-Dec-2020|
|Date of Web Publication||19-Feb-2021|
Mrs. Remiya Mohan
College of Nursing, All India Institute of Medical Sciences, Basni Industrial Area, Jodhpur - 342 005, Rajasthan
Source of Support: None, Conflict of Interest: None
Pandemics and epidemics befall almost every decade. History documents pandemics since 430 BC. Each outbreak is suspected to be related to a minuscule creature which is new to the world or with a mutation. In recent years, viruses have caused multiple disease outbreaks leading to significant global public health menace. Although we have moved and reached new heights in modern scientific medicine, there remains a gap in understanding of environmental risk factors, disease pathogenesis and apt approach towards its management. This article outlines the major disease outbreaks that affected global proportions and had a marked impact on the human civilisation, starting with historical outbreak of plague, Spanish flu, severe acute respiratory syndrome, Ebola, Zika, Nipah and Middle East respiratory syndrome to the most recent coronavirus disease 2019.
Keywords: Coronavirus study group, epidemics, International Committee on Taxonomy of Viruses, pandemics, virus
|How to cite this article:|
Mohan R, Pandey V. Pandemics and epidemics: Past to present. Indian J Cont Nsg Edn 2020;21:110-6
| Introduction|| |
Ebullition of pandemics and epidemics befalls every decade and shows the world that a mere microscopic creature can have a devastating effect on human civilisation. The viruses are the known culprits of pandemics, and most of them have their origin from animal viruses. Pandemics usually are caused by microbes which are new to the world, and the population lacks immunity to this novel agent. The study of disease dynamics has become easier with technological advancement, but at the same time, these advances along with human mobility have been linked to emergence of infectious diseases.
Remarkable story of pandemics starts from the Spanish influenza virus outbreak, considered to be the mother of all pandemics, but now, we have a new malady, the coronavirus disease 2019 (COVID-19) which has mushroomed itself across the globe. This article highlights the most notable pandemic outbreaks of human history, which changed the shape of societies and way of development of scientific technology, especially medicine.
| Historical Pandemics|| |
Many outbreaks of plague are documented in the history. Common of them were [Flow chart 1]:
The Athenian Plague of 430 BC also known as 'Plague of Athens' claimed 25% lives. The outbreak started in Ethiopia and outspread to Egypt and Greece. Symptoms were fever, body rash, headache, conjunctivitis, haemoptysis and death within a week. The survivors suffered from blindness, amnesia and paralysis for entire life. The cause is not clearly understood but bubonic plague, Ebola virus haemorrhagic fever and typhoid fever are probable culprits.
The Antonine Plague of 165–180 AD is thought to be caused by smallpox. Antonine Plague was documented by Galen, therefore, this outbreak is also known as the 'Plague of Galen'. It is also considered to be a reason for the fall of Roman empire.,
The outbreak of Antonine Plague occurred in Mesopotamia in the late 165 AD during the reign of Roman emperor Marcus Aurelius. The symptoms were fever, rash over the entire body, swollen throat, vomiting, cough, excessive thirst and gastrointestinal bleeding. People who survived developed immunity. Based on information provided by Galen, modern scientists concluded that this disease was smallpox.
Antonine Plague outbreak falls out twice. The first phase of outbreak was from 165 to 180 AD and second from 251 to 266 AD. The second outbreak was more devastating than the first as the estimated deaths were 2000/day and 5000/day in the first and second phases, respectively. It is estimated that one-third of the entire population perished (60–70 million). The Roman emperor Marcus Aurelius succumb to the same illness.
The Justinian Plague spread in the reign of King Justinian. The point of origin was Egypt. The plague arrived in Constantinople in 542 AD. It was a 'real plague' pandemic that originated in the mid-sixth century AD, established a permanent cycle of infection that lasted for 225 years and vanished in 750 AD., Mortality was immoderate, graveyards were overflowing and dead bodies were buried in walls of towers. There was economic crisis and starvation. It is estimated that the population dwindled by 40%–50%. The DNA analysis of bones revealed causative organism as Yersinia pestis causing bubonic plague. The disease manifested as hallucinations, fever, fatigue, buboes in armpits and groins and haemoptysis.
The management was by medical professionals and home management. The incorporated home remedies were bathing in cold water, applying powder or wearing rings, anklets blessed by saints and included quarantine.
| Black Death 1334–1351|| |
Black Death was the outbreak of bubonic plague which incepted from China in 1334. It appeared in Europe in 1347 following the trading route known as the Silk Road. In an article, DeWitte mentioned that it killed 30%–40% lives in Europe between 1347 and 1351.
The cause of this horrifying mortality was not understood at that time; it was considered as 'Punishment for sins'. In the 19th century, French biologist Alexandre Yersin discovered this microbe as Y. pestis. There was shortage of doctors, many towns appointed special doctors known as 'plague doctors'. In 1348, Venice was among the first city-states to appoint dedicated health officials to deal with plague.
Quarantine was the method used to control Black Death. 'Quarantine' term was introduced in the 14th century. This word is derived from Italian words quaranta giorni which mean 40 days. The first known quarantine was enacted in Ragusa (City-state of Dubrovnik) in 1377, where all individuals arriving had to spend 30 days on an island of Lokrum before permitting to enter the city. This period of 30 days (trentine) was later extended to 40 days (quaranta giorni or quarantine).
| Spanish Flu Pandemic 1918–1920|| |
The 1918 Spanish flu is one of the most dreadful pandemics that spread globally. It is considered as the first pandemic of modern medicine.
The origin of Spanish flu caused by H1N1 (genes of avian origin) is still unclear. In 1918, it was first identified in United States military personnel and it is believed that it further spread through them. One-third of the world's population (about 500 million) became infected with this virus along with death of up to 50 million people, more than the death toll from the First World War.
As there was no vaccine to treat diseases or antibiotics to deal with the secondary infections, the outbreak was decelerated through non-pharmaceutical interventions such as quarantine, closing schools, theatres, adopting personal hygienic measures and use of disinfectants. Remembering this pandemic, in 2018, the Centers for Disease Control and Prevention (CDC) released an article, 'We Remember, We Prepare'. The CDC reports that high mortality was seen in <5-year-old and more than 65-year-old age group. One unique feature of this outbreak was that it affected the age group of 20–40 years old too.
This pandemic has a long lingering effect. A study of US census data from 1960 to 1980 found that the children born to women exposed to the pandemic had more physical ailments, lower educational attainment and lesser lifetime income resulting in lower socioeconomic status than those born a few months earlier or later.
| Smallpox Unknown Origin Till 1977|| |
The history of genesis of smallpox goes back to many 1000 years. Global eradication of smallpox is one of the greatest achievements of medicine and mankind. Smallpox, caused by the variola virus, is highly contagious disease with acute manifestations of fever, headache, vomiting and appearance of rash on the 3rd day. Edward Jenner developed the world's first natural vaccine against smallpox in 1798 by using mild cowpox virus.
Prior to the discovery of small pox vaccine, variolation (inoculation of smallpox pustule materials through inhalation or scratching of skin) was used to control spread of smallpox. Variolation resulted in less mortality as compared to naturally acquired smallpox.
In 1972, smallpox outbreak in the former Yugoslavia started with a pilgrim returning from the Middle East, who developed fever and skin eruptions. The outbreak resulted in 174 cases and 35 deaths. The last case of naturally occurring smallpox was reported in Somalia in October 1977.
After an intensified worldwide smallpox eradication campaign of almost 20 years, the World Health Assembly declared global smallpox eradication in May 1980. The last known case in India occurred in May 1975, and India was declared smallpox free on 5 July 1975. Although all countries have discontinued routine vaccine of smallpox, the World Health Organization (WHO) maintains a reserve stock smallpox vaccine and needles to protect approximately 200 million populations.
| Human Immunodeficiency Virus/Acquired Immune Deficiency Syndrome 1981–Till Date|| |
Human immunodeficiency virus (HIV) infection was previously considered as a death sentence, but ameliorated preventive, diagnostic and treatment modalities have made HIV infection manageable and allowed acquired immune deficiency syndrome (AIDS) suffers to live a long and healthy life.
In June 1981, the first case of AIDS was reported in the USA. Since then, HIV has claimed 33 million lives so far. An estimate by the WHO mentioned that by end of 2019, 38 million people will be living with HIV.
Previously, HIV was called lymphadenopathy associated virus by French scientists and human T-cell lymphotropic virus III by researchers in the USA. In 1986, the International Committee on Taxonomy gave it the name HIV.
HIV causes a potentially a life-threatening disease called AIDS that attacks immune system and shoves individual towards infections. The most advanced stage of HIV infection is AIDS. HIV is of two types: HIV1 (most common) and HIV2. In HIV infection, the CD4 cells decrease, a count below 200 suggests severe immune compromise. The WHO manifests AIDS in four clinical stages ranging from clinical Stage 1 (asymptomatic) to clinical Stage IV (AIDS). The initial stage manifests as flu-like symptoms or no symptoms. As the infection progresses, it decreases the immunity and causes many diseases such as tuberculosis, Kaposi sarcoma and cancers. The virus is transmitted through blood and body fluids such as semen, breast milk and vaginal secretions. Transmission shifts from highest risk group (sex workers, drug users and homosexual man) to bridge population (migrant population, clients of sex workers, partners of drug users and patients with sexually transmitted disease) and then to general population. A time lag of 2–3 years is observed between shifts from one to another group. The main route of HIV epidemic in India is hetrosexual (88.2%). The laboratory diagnosis of ELISA and Western blot are done to confirm the diagnosis.
Currently, there is no cure or vaccine for HIV, but free antiretroviral therapy (ART) is a boon for patients. In India, ART program was launched in April 2004. Individuals who are on ART do not transmit disease as they are virally suppressed. In India, the first reported case was in 1986 among female sex workers in Chennai, and in due course, the first clinically reported case was from Mumbai in 1986. Till 1987, 135 cases were reported, and among them, 14 had already progressed to AIDS.
Since 1998, the National AIDS Control Organization, Ministry of Health and Family Welfare (MoHFW) in collaboration with the Indian Council of Medical Research–National Institute of Medical Statistics, undertakes biennial HIV estimations which provide critical information of the current scenario and future planning. According to latest estimates in 2019, 69.22 thousand new HIV infections have been reported which have declined by 86% in 1997 (peak). In 2019, AIDS-related deaths are 58.96 which have declined by 78% as in 2005 (peak). The annual infection rate of India has decreased by 37% since 2010 (except in Chhattisgarh, Chandigarh, Tripura and Arunachal Pradesh). Nationally, AIDS mortality in 2019 is estimated as 4.43/100,000 populations (peak was 25 in 2004–2005).
| Severe Acute Respiratory Syndrome 2003|| |
Severe acute respiratory syndrome (SARS) is a respiratory illness caused by a SARS-associated coronavirus (SARS-CoV-1). This was a new virus, not reported before. The first case of SARS was reported in Asia in February 2003. This infectious disease spread to 29 countries, where 8096 people got infected with SARS and mortality was 774. Fever, shivering, headache, myalgia and diarrhoea were the most common manifestations reported by affected individuals.
The natural reservoir of SARS is horseshoe bat. The mode of transmission is with respiratory droplet or fomites. The virus is shed in stool, but reports are not available on faecal oral transmission. Intensive support is required for severe cases. During the epidemic in 2003, the management included ARTs, immunoglobulins and corticosteroids. Further researches are required to confirm the efficacy. There is no vaccine against SARS, so emphasis should be on preventive aspects.
CDC along with the WHO worked extensively and promptly to address the SARS issue. This global outbreak was contained in July 2003. Since 2004, no SARS cases have been reported anywhere in the world.
| Middle East Respiratory Syndrome Coronavirus 2012–Till Date|| |
The first case of Middle East respiratory syndrome (MERS) CoV was identified from Saudi Arabia in September 2012. Investigating retrospectively, it was revealed that Jordan reported first cases of MERS in April 2012. Hitherto maximum cases of MERS have been identified in residents of the Arabian Peninsula. In 2015, the Republic of Korea reported MERS in travellers returning from the Arabian Peninsula.
The WHO data reveal that till January 2020, the globally reported cases are 2519 with majority of cases 2121 from Saudi Arabia. Owing to the geographical distribution of the disease, the CoV Study Group of the International Committee on Taxonomy of Viruses (ICTV) decided to name this new CoV as MERS-CoV., Clinical manifestations of MERS in humans include cough, shortness of breath, fever and pneumonia.
Dromedary camels are found to be the reservoir host for MERS-CoV, and studies suggest that humans are infected with direct or indirect contact with these camels. No vaccination or treatment is currently available for MERS-CoV. The pathogenesis of MERS-CoV infection to date is not well understood and further research is necessary.
| H1N1 2009–Till Date|| |
In 2009, a novel virus attacked the human population. This was a reiteration of 1918 Spanish flu outbreak but less calamitous. H1N1 first emerged in 2009 April in Mexico and soon expanded globally. On 11 June 2009, the WHO announced H1N1 as the first influenza pandemic of the 21st century. Suspected as a re-assortment of bird, swine and human flu viruses, it was colloquially known as the 'swine flu' disease by influenza A (H1N1) virus. The manifestations of H1N1 are cough, throat pain, common cold, fever, breathlessness, headache, chest pain, sputum production, vomiting and haemoptysis.
CDC estimated mortality of approximately more than five lakh people worldwide from H1N1 virus infection during the 1st year the virus circulated. CDC also estimated that 80% of virus-related death was in people younger than 65 years of age. These data are typically different, as in influenza epidemics, up to 90% deaths are in people 65 years or more. It is believed that this happened because adults had immunity due to a similar H1N1 outbreak in the distant past.
The first case in India was reported from Hyderabad on 16 May 2009, from a traveller from the United States. According to official website of the National Centre for Disease Control since 2018, thousands of people are infected with H1N1 every year. According to the WHO, H1N1 is now a regular human flu and seasonally circulate worldwide.
| Ebola Virus Disease 1976, 2013–2015|| |
The word Ebola is derived from the 'Ebola River' where the first outbreak occurred. In 1976, the emergence of Ebola virus disease (EVD) was seen in different parts of Central Africa. The first outbreak was reported in the Democratic Republic of the Congo formerly known as Zaire. The second outbreak occurred in South Sudan. Research revealed that these were two genetically distinct but phylogenetically related Ebola viruses Zaire ebolavirus and Sudan ebolavirus. Since its discovery, Africa has witnessed most outbreaks. In 2014, the outbreak of Ebola began in West Africa in a rural setting of south-eastern Guinea, and within weeks spread to urban areas and across borders, and within months became a global epidemic. The 2013–2015 West Africa Ebola outbreak is documented as longest, geographically extensive and most fatal outbreak of Ebola. The disease manifests as haemorrhagic fever, aches in various body parts, sore throat, vomiting and diarrhoea. The average fatality rate of EVD is 50%. In the past outbreaks, case fatality rates were 25%–90%. Direct interactions with wildlife, encroachment into forests and travelling are few reasons for spread of disease.
The WHO published a formal notification of Ebola virus on 23 March 2014, and on 8 August, the WHO declared the epidemic as a 'public health emergency of international concern'.
The virus is transmitted through direct contact with blood, organs and body secretions of animals (fruit bats, monkeys and chimpanzee). In humans, the virus is transmitted by direct contact with blood and body fluids of symptomatic individuals. Asymptomatic cases of Ebola are non-infectious, and the virus is not transmitted through air, water or food.
During this epidemic, 74% of transmission was between family members. The most figured out cause was direct contact with dead bodies of infected people. EVD is controlled by package of interventions which include infection prevention and control, appropriate contact tracing, adoption of safe mourning and burial practices.,
| Zika 1952–Till Date|| |
Zika virus was first detected in 1947 in monkeys of Uganda. Later, in 1952, it was identified in Uganda and the United Republic of Tanzania. It is a mosquito-borne disease caused by Aedes, which bite during day. The first outbreak of Zika virus was in 2007 from the island of Yap (Federated States of Micronesia). Again, in 2013, the infection spread in French Polynesia and other countries and territories in the Pacific. Most cases were asymptomatic or reported mild symptoms including fever, rash, conjunctivitis, muscle and joint pain, malaise or headache. Infection during pregnancy may result in microcephaly or other brain abnormalities in newborns. Brazil reported a large outbreak in March 2015. In the same year July and October, it was associated with Guillain–Barre syndrome and microcephaly, respectively. Till date, this virus has been reported in 86 countries and territories.
India reported the first four confirmed cases of Zika virus infection in 2017, among which 3 were in Ahmedabad district of Gujarat and one in Krishnagiri district of Tamil Nadu. In 2018, there was a major outbreak in Rajasthan and Madhya Pradesh. Till 2 November 2018, 157 cases were reported, including 63 pregnant women. Fortunately, the outbreaks in India were not associated with neurological complications.
| Nipah Virus 1999–2018|| |
In 1999, Malaysia and Singapore reported the first outbreak of Nipah virus infection. The name of Nipah originated from a village in Malaysian Peninsula known as Sungai Nipah. It was identified among people with close contact with pigs (pig farmers) who manifested with encephalitis and respiratory illness. Bat species were identified as the reservoir for Nipah virus. The disease manifests as fever, vomiting, sore throat, respiratory infection, myalgia, headache and fatal encephalitis. Within 48 h, these manifestations may progress to coma. As there is no cure, it kills about 75% of people it infects.
Again in 2001, Nipah virus infected people in Bangladesh, but this time, the strain was different from 1999. India has witnessed three outbreaks of Nipah virus infection, first two in West Bengal in 2001 and 2007 and the latest and the first outbreak in South India was in Kerala on 19 May 2018.
The recent Nipah outbreak was in two districts of Kerala – Kozhikode and Malappuram. The confirmed cases were 18, out of which 16 died. The outbreak was contained with focus on prevention and control of infection. The use of personal protective equipment, isolation of infected cases and their contacts and decontaminating the surfaces were the major steps. The role of surveillance was paramount; 2500 contacts were monitored. Prompt advisory by state and the dedication of health workers resulted in successful containment of outbreak within 3 weeks.
| Coronavirus Disease 2019|| |
COVID-19 outbreak is a public health emergency of global proportions. The first human case of COVID-19 was reported in Wuhan city, China, in December 2019. As they were unable to identify the causative agent, these first cases were classified as 'pneumonia of unknown aetiology'. The aetiology of this illness is now attributed to a virus from CoV family. On 11 February 2020, the ICTV announced the name of '2019 novel coronavirus' as 'SARS-CoV-2'. This virus is genetically related to the CoV responsible for the SARS outbreak of 2003. Along with this, the WHO announced the name of this new disease as COVID-19 which is the acronym of 'coronavirus disease 2019'. On 12 March 2019, the WHO declared COVID-19 as pandemic. Since then, it has extended itself over the entire globe.
Field investigations were conducted to identify the origin of virus. An epidemiologist conducted surveys to identify where did the infected people went just prior of being infected. The results reflect that the virus came from seafood market.
COVID-19 is highly infectious and manifests wide range of symptoms and can cause mild to severe illness. Symptoms usually appear within 2–14 days of exposure to virus. Common manifestations include pyrexia, cough, sore throat, and headache, loss of taste or smell, weakness, body ache, diarrhoea, nausea/vomiting. Warning signs requiring hospitalisation are difficulty in breathing, chest pain, confusion, altered consciousness and bluish discoloration of face or lips. The disease is life threatening in older adults and people of any age with serious underlying medical problems.
The virus spreads among people with close contact (within 6 feet) through coughing, sneezing and talking. Sometimes, there may be air-borne transmission and through contact with infected surface. Non-symptomatic infected person can also spread virus. Curtailment procedures include frequent handwashing preferably with soap and water, if soap and water are not available then with hand sanitiser (containing at least 60% alcohol), practice social distancing, covering mouth and nose with mask at public places and monitoring self and family health daily.
Spread of COVID-19 can be monitored by identifying the contacts, testing the suspected cases, effective isolation and monitoring of the infected and their close contacts for at least 14 days. According to the MoHFW, India reported the first case of COVID-19 on 30 January 2020 in Kerala. The case was a student studying in Wuhan University. The cases of COVID-19 in India and around the globe are rising at an alarming rate. In India as on 2 July 2020, MoHFW has confirmed 8,555,795 cases and 128,121 deaths. The global scenario is similar with 51,251,715 cases and 1,270,930 deaths with 220 countries affected.
As this pandemic is spreading, its effects are also zooming and encompassing psychological aspects also. There is uncertainty of present and future. As the elderly are at higher risk of morbidity and mortality, special concern is to shell them in a loving and protective environment. Along with adults, children are equally touched with physical and psychological impact of the disease. In this stressful environment, caregivers should listen to them, understand them and assure them that they are safe.,
| Conclusion|| |
As decades are passing, new diseases are emerging telling us about the nature's unpredictable powers. It is said that infectious disease will last as long as humanity itself. The growth of these diseases causing microbes, especially viruses, is becoming a serious threat to public health. As mentioned in this article, the last 20 years has witnessed many viral disease outbreaks. Globalisation has dramatically facilitated the problem because outbreaks that were previously localised can now become global very rapidly, i.e., within hours the disease can spread far from its origin.
It is high time that the disease outbreak management strategies are modified to prevent them through an articulated plan of action rather than just responding to an outbreak. Global preventive aspects such as immunisation and handwashing habits should be nurtured as it is not only better than cure but cheaper too. It is required to control the re-emergence of old diseases and emergence of new diseases through strengthening holistic healthcare system.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Christaki E. New technologies in predicting, preventing and controlling emerging infectious diseases. Virulence 2015;6:558-65.
Taubenberger JK, Morens DM. 1918 Influenza: The mother of all pandemics. Emerg Infect Dis 2006;12:15-22.
Huremović D. Brief history of pandemics (pandemics throughout history). In: Psychiatry of Pandemics. 2019. p. 7-35. [doi: 10.1007/978-3-030-15346-5_2].
Sabbatani S, Fiorino S. The antonine plague and the decline of the Roman Empire. Infez Med 2009;17:261-75.
Haas C. La peste antonine [the antonine plague]. Bull Acad Natl Med 2006;190:1093-8.
Horgan J. Justinian's Plague (541–542 CE). Ancient History Encyclopedia; December 26, 2014. Available from: https://www.ancient.eu/article/782/
. [Last accessed on 2020 Nov 03].
DeWitte SN. Mortality risk and survival in the aftermath of the medieval black death. PLoS One 2014;9:e96513.
Sehdev PS. The origin of quarantine. Clin Infect Dis 2002;35:1071-2.
Almond D. Is the 1918 influenza pandemic over? Long-term effects of in utero
influenza exposure in the post-1940 U.S. population. J Polit Econ 2006;114:672-712.
Park K. Park's Textbook of Preventive and Social Medicine. 23rd
ed. Jabalpur: Bhanot; 2015.
Tripathy SP. History of HIV in India. In: Lu Y, Essex M, Stiefvater E, editors. AIDS in Asia. Boston, MA: Springer; 2004.
Centres for Disease Control and Prevention. Disease of the Week: SARS (10 Years After). Available from: https://www.cdc.gov/dotw/sars/index.html#
. [Last accessed on 2020 Jun 10; Last updated on 2016 Mar 03].
Centres for Disease Control and Prevention. Severe Acute Respiratory Syndrome (SARS). Available from: https://www.cdc.gov/sars/index.html
. [Last accessed on 2020 Jun 10; Last updated on 2017 Dec 06].
Al-Osail AM, Al-Wazzah MJ. The history and epidemiology of Middle East respiratory syndrome corona virus. Multidiscip Respir Med 2017;12:20.
de Groot RJ, Baker SC, Baric RS, Brown CS, Drosten C, Enjuanes L, et al
. Middle east respiratory syndrome coronavirus (MERS-CoV): Announcement of the coronavirus study group. J Virol 2013;87:7790-2.
El-Kafrawy S, Corman V, Tolah A, Al Masaudi S, Hassan A, Müller M, et al
. Enzootic patterns of Middle East respiratory syndrome coronavirus in imported African and local Arabian dromedary camels: A prospective genomic study. Lancet Planet Health 2019;3:e521-8.
Ramadan N, Shaib H. Middle East respiratory syndrome coronavirus (MERS-CoV): A review. Germs 2019;9:35-42.
Trifonov V, Khiabanian H, Rabadan R. Geographic dependence, surveillance, and origins of the 2009 influenza A (H1N1) virus. N Engl J Med 2009;361:115-9.
Centres for Disease Control and Prevention. H1N1 Flu: WHO Pandemic Declaration Historic Archive. Available from: https://www.cdc.gov/h1n1flu/who/
. [Last accessed on 2020 Jun 15].
Kshatriya RM, Khara NV, Ganjiwale J, Lote SD, Patel SN, Paliwal RP. Lessons learnt from the Indian H1N1 (swine flu) epidemic: Predictors of outcome based on epidemiological and clinical profile. J Family Med Prim Care 2018;7:1506-9.
] [Full text]
Baseler L, Chertow DS, Johnson KM, Feldmann H, Morens DM. The pathogenesis of Ebola Virus disease. Annu Rev Pathol 2017;12:387-418.
Gupta, Nitin & Kodan, Parul & Baruah, Kalpana & Soneja, Manish & Biswas, Ashutosh. (2019). Zika virus in India: past, present and future. QJM: An International Journal of Medicine. 10.1093/qjmed/hcz273.
Thomas B, Chandran P, Lilabi MP, George B, Sivakumar CP, Jayadev VK, et al
. Nipah Virus infection in Kozhikode, Kerala, South India, in 2018: Epidemiology of an outbreak of an emerging disease. Indian J Community Med 2019;44:383-7.
] [Full text]
Cascella M, Rajnik M, Cuomo A, Dulebohn SC, Napoli RD. Features, Evaluation and Treatment Coronavirus (COVID-19). StatPearls; 2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554776/
. [Last accessed on 2020 Nov 03].
Cucinotta D, Vanelli M. WHO Declares COVID-19 a Pandemic. Acta Biomed 2020;91:157-60.
Ministry of Health and Family Welfare. COVID-19 INDIA. Available from: https://www.mohfw.gov.in/
. [Last accessed on 2020 Nov 12; Last updated on 2020 Nov 12].