Are there diseases deadlier than Covid-19? Here are 10 that may cause the next pandemic, warn experts
Scientists warn that even after the current pandemic is under control, the potential for others is ‘very real’
The coronavirus pandemic has been a wake-up call for the world to be more vigilant about viruses and zoonotic diseases — those that jump from animals to humans. Professor Jean-Jacques Muyembe Tamfum, the scientist who helped discover the Ebola virus, cautions that there are chances of diseases deadlier than Covid-19 emerging in the future.
"We are now in a world where new pathogens will come out. And that’s what constitutes a threat for humanity," he told CNN. When asked if future pandemics could be more apocalyptic, Tamfum replied, “Yes, yes, I think so.”
Scientists have been on high alert for ‘Disease X’, a novel pathogen for which there is no cure or vaccine yet. According to Gavi, the Vaccine Alliance, 10 infectious diseases could be the next pandemic. Most of these diseases are also listed by the World Health Organization (WHO) as current priority diseases. “Many diseases identified by WHO normally exist in animals, so the likelihood of outbreaks increases when animals and people more frequently come into close contact, such as through habitat encroachment, animal husbandry and wildlife trade. So, this, combined with other factors like air travel, urbanization, and climate change means that, even after this pandemic is under control, the potential for others is very, very real,” suggest experts.
What are these diseases?
It was only in February 2020 that the Democratic Republic of the Congo (DRC), Burundi, Ghana, Rwanda, Uganda and Zambia approved an Ebola vaccine. This is six years after the Ebola pandemic struck West Africa. In 2014, West Africa had 28,616 Ebola cases and 11,310 deaths. In the DRC outbreak from 2018-2020, 3,481 cases and 2,299 deaths have been reported to the WHO.
Ebola needs close human contact to spread as it is transmitted through direct physical contact with infected bodily fluids, especially blood, feces and vomit. This puts families of infected people and health care workers at extremely high risk.
Marburg virus disease
A highly deadly disease, it kills about 88% of people it infects. It spreads similarly to Ebola, causes the same symptoms, and even touching a deceased patient can result in transmission. In 2017, in the most recent outbreak in Uganda, there were three cases, all of whom died. A previous outbreak in 2005 in Angola resulted in over 200 infections, 90% of whom died.
It is a viral hemorrhagic illness that damages organs and ruptures blood vessels. According to Gavi, every one in five people infected with the Lassa virus has severe disease affecting the liver, spleen or kidneys.
“The virus is often transmitted by the urine or feces of Mastomys rats, native to Africa, via contaminated household objects. Health workers who are in contact with the blood or organ tissue of patients can become infected too. Lassa fever infection can result in long-term hearing loss after recovery,” say experts. In several West African countries, where outbreaks have occurred, the infection has killed between 1% to 15% of those infected. Due to the limited amount of surveillance and little evidence about deaths in the region, there is no precise tally of how many lives the virus has claimed so far. Experts estimate there are between 100,000 and 300,000 infections of Lassa fever annually, with around 5,000 deaths overall.
Since it was first detected in 2012 in Saudi Arabia, sporadic outbreaks have caused 2,519 cases and 866 deaths. So far, MERS-CoV is not known to spread easily from person to person, unless they are in close contact.
It has already caused a pandemic in 2003, which infected over 8,200 people and killed 775. "There is no guarantee that the SARS virus won’t return, and cause much greater damage. Similar to Covid-19, the virus is thought to be transmitted by respiratory droplets produced when an infected person sneezes or coughs,” warn scientists.
The virus is a distant cousin of the measles virus and can kill up to 75% of people it infects. It first emerged in 1998 and has been spotted frequently since in South-East Asia. Nipah is common in bats, specifically fruit bats in South-East Asia. It spreads through close contact with infected pigs and raw food contaminated with urine or saliva from infected bats. Infection through respiratory secretions such as coughs and sneezes when people are in close contact can also occur. The main concern is what happens if the virus mutates, enabling it to spread faster. As early as 2018, an outbreak in Kerala, India, led to 23 cases and 17 deaths.
It mostly causes mild disease, including fever, rash and muscle pain. However, between 2015 and 2016, the virus caused birth defects, which were referred to as ‘congenital Zika syndrome’. There is a higher risk of miscarriage and babies born to pregnant women infected with Zika are at risk of microcephaly. In 2015 and 2016, there were more than 500,000 cases of Zika and 18 deaths, and 3,700 babies were born with birth defects.
Zika virus is spread by Aedes mosquitoes, which also transmit dengue and chikungunya viruses. "The rapid spread of Zika virus in the western hemisphere in 2015 and 2016 demonstrates its pandemic potential," states Gavi.
Crimean-Congo hemorrhagic fever
It is mostly restricted to animals spread through tick bites. However, humans can catch it too if they come in contact with a recently slaughtered animal that was infected. There have been some reports of human-to-human transmission through exposure to bodily fluids of infected people. It is endemic to many countries in Asia, Africa and the Balkans, where the tick species that spreads it is found. In 2018, there were 483 cases and 59 deaths in Afghanistan.
Initially, the virus causes flu-like symptoms. However, if not caught early enough, the Crimean-Congo hemorrhagic fever can result in severe and uncontrollable bleeding.
Rift Valley fever
It is also known to restrict itself to animals. Instead of ticks, mosquitos carry the disease. But people can get infected when they come into contact with bodily fluids such as blood or milk of infected animals. They can also be infected through mosquito bites. No case of human-to-human transmission has been reported so far. While a mild case in humans can cause fever and muscle aches, more severe cases can lead to blindness, swelling of the brain or uncontrollable bleeding. "As a disease particularly sensitive to the El Niño phenomenon, the increase in extreme weather events, related to climate change, drive increased risk of spread," caution researchers.
While smallpox has been eradicated, its cousin called monkeypox continues to pose a threat. It causes symptoms similar to smallpox, such as a widespread pustular rash with fever and exhaustion.
It is mostly spread by contact with wild animals such as rodents and primates but can be transmitted between people through contact with lesions, body fluids, respiratory droplets or contaminated clothes or bedding. The vaccinia vaccine that was used to eradicate smallpox can also protect against monkeypox. A new third-generation vaccinia vaccine has now been approved for preventing monkeypox.
“Global travel and trade in pets have caused monkeypox to spread from Central and West Africa to North America and European countries such as the UK, although all resulting outbreaks have been brought under control so far,” note experts.