There will be another global pandemic.
It might be a virus, bacteria, fungi, protozoa, or prion. It might spread via air, water, surfaces, insects, skin, or blood. It might come from an animal or be developed in a lab.
We don’t know when. We don’t know what. But we do know it's coming. Thus, it would be wise for organizations and governments to start preparing now.
In Part One of this series, we discussed 5 viral families already in the United States with pandemic potential. However, the tropics carry some of the most interesting (and most concerning) viruses. Per the World Health Organization (WHO), here are 5 more viral families that could spark the next pandemic.
Notes on Terminology and Selection
Priority vs. Prototype Pathogens: The WHO’s most recent guidelines prioritize research into viral families rather than specific viral variants. They can thus target research into pathogens which are a threat now (priority pathogens) while simultaneously keeping an eye on certain pathogens from the same family (prototype pathogens). Note that some viruses are both priority and prototype pathogens.
Pandemic vs. PHEIC: The WHO’s guidance does not use the term “pandemic” but instead rates pathogens by their potential to cause a Public Health Emergency of International Concern (PHEIC). This might mean a local epidemic that has international implications, or it might mean a true global pandemic. We limited our list to viral families with at least one member rated as having a high PHEIC risk.
Arenaviridae: Why Mice Aren’t Cute
Priority Pathogen(s): Mammarenavirus lassaense
Prototype Pathogen(s): Mammarenavirus lassaense, Mammarenavirus juninense, Mamastrovirus virginiaense
Common Name(s) for Disease(s): Lassa Fever, Argentine Hemorrhagic Fever
Arenaviridae include Mammarenavirus lassaense — a virus spread by the urine and droppings of multimammate rats in West Africa. When humans are infected, this leads to Lassa fever. While 80% of cases result in mild symptoms, the remaining 20% can result in bleeding, swelling, difficulty breathing, and shock. Also, 1 out of 3 cases can lead to hearing loss. Meanwhile, the related Mammarenavirus juninense, also spread by rodents, causes fevers and gastrointestinal distress during the harvest season in Argentina.
Since each instance of this family specializes in certain rodents, the strains remain geographically isolated. However, one strain could theoretically adapt to multiple rodent species, allowing a novel arenavirus to spread globally.
Filoviridae: The Blood Price of Poverty
Priority Pathogen(s): Orthoebolavirus zairense
Prototype Pathogen(s): Orthoebolavirus zairense, Orthomarburgvirus marburgense, Orthoebolavirus sudanense
Common Name(s) for Disease(s): Ebola, Marburg
Filoviridae are spread through close human contact and bodily fluids. In the final stages of some diseases, victims bleed through their own pores. The spread of these Ebola-like viruses outside of Africa had long been the imaginative subject of fictional Hollywood disasters. Then it actually happened.
Fortunately, the resources of wealthy countries allowed for the rapid creation of a vaccine; thus, the disease isn’t much of a threat in the West. Yet limited vaccine accessibility in the countries where Ebola still spreads (plus the wide variety of newly discovered filoviridae relatives) means that this virus family remains a global threat.
Nairoviridae: Come for the Animal Husbandry; Stay for the Sudden Liver Failure
Priority Pathogen(s): Orthonairovirus haemorrhagiae
Prototype Pathogen(s): Orthonairovirus haemorrhagiae
Common Name(s) for Disease(s): Crimean Congo Haemorrhagic Fever
Orthonairovirus haemorrhagiae is spread to humans from ticks or through contact with the blood and tissue of infected herd animals. It is found on 3 continents and has a 10-40% fatality rate. We think the WHO describes the terrifying symptoms best:
“Onset of symptoms is sudden, with fever, myalgia, (muscle ache), dizziness, neck pain and stiffness, backache, headache, sore eyes[,] and photophobia (sensitivity to light). There may be nausea, vomiting, diarrhoea [sic], abdominal pain[,] and sore throat early on, followed by sharp mood swings and confusion. After [2] to [4] days, the agitation may be replaced by sleepiness, depression[,] and lassitude, and the abdominal pain may localize to the upper right quadrant, with detectable hepatomegaly (liver enlargement). | Other clinical signs include tachycardia (fast heart rate), lymphadenopathy (enlarged lymph nodes), and a petechial rash (a rash caused by bleeding into the skin) on internal mucosal surfaces, such as in the mouth and throat, and on the skin. The petechiae may give way to larger rashes called ecchymoses, and other haemorrhagic phenomena. There is usually evidence of hepatitis, and severely ill patients may experience rapid kidney deterioration, sudden liver failure[,] or pulmonary failure after the fifth day of illness.”
Paramyxoviridae: Fruit Bats and Pigs and Humans! Oh My!
Priority Pathogen(s): Henipavirus nipahense
Prototype Pathogen(s): Henipavirus nipahense
Common Name(s) for Disease(s): Nipah
The Nipah virus is transmitted from bats and pigs to humans. It causes a range of illnesses from asymptomatic infections to severe respiratory issues and fatal encephalitis, with a case fatality rate of 40% to 75%. According to the WHO, “There is no treatment or vaccine available for either people or animals. The primary treatment for humans is supportive care.” The virus has caused outbreaks in Asia, notably in Malaysia, Bangladesh, and India.
Togaviridae: What’s that Buzzing Sound?
Priority Pathogen(s): Alphavirus chikungunya, Alphavirus venezuelan
Prototype Pathogen(s): Alphavirus chikungunya, Alphavirus venezuelan
Common Name(s) for Disease(s): Chikungunya, Venezuelan Equine Encephalitis
The mosquito-borne togavirus that causes Eastern Equine Encephalomyelitis (EEE) has been circulating in the United States since the 1800s. Human cases are rare, but those who survive often have permanent neurological impairment.
However, the WHO is more concerned about a newly discovered tropical relative of EEE — Chikungunya. Information on this new virus is extremely limited. A study of an outbreak in Minas Gerais, Brazil, found that the mortality rate of this new virus is 60 times higher than initially supposed.
Don’t Cancel Your Tropical Vacation
Humans like to predict the future, even if that future seems dark. However, we’re not very good at it. All or none of these viruses may become a global problem in the future.
While we should be preparing for another global pandemic, there’s no need to cancel your tropical vacation (that is, as long as you follow local and federal health advisories.)
If you want some additional travel tips, our past blogs are the perfect airport reading.
