The Picornaviruses

The Picornavirus family is very large indeed, but in general its members are not particularly close. There are more than 150 species of Picornavirus, currently categorised into more than 60 subgroups. Several of these subgroups — including the Enteroviruses, the Hepatoviruses and the Rhinoviruses — contain viruses that can infect people, and it is these that disease detectives want to watch most closely for future human outbreaks.

Prime Suspects 

The highly infectious Poliovirus is the most infamous of all the Picornaviruses and the culprit behind millions of cases of paralysis in people all across the world. Among other suspects of interest to disease detectives are the Coxsackieviruses and the Enteroviruses, which can cause a range of diseases in people, from viral meningitis to infections of the heart known as myocarditis, to Hand, Foot and Mouth Disease or HFMD. One newly emerging prime suspect among the Enteroviruses is Enterovirus-D68, or EV-D68, which has been found to cause a serious neurologic condition called Acute Flaccid Myelitis, or AFM.  Hepatitis A virus, which causes liver disease, is another Picornavirus to watch, as are the many Rhinoviruses that cause common colds in people.
 

Nicknames and Aliases 

The name of this family—Picornaviruses—is a construct of ‘pico’ and ‘Ribonucleic Acid’, or RNA, and means ‘small RNA-containing viruses’.

The name Poliomyelitis comes from the Ancient Greek  words ‘polios’, meaning ‘grey’ and ‘myelos’, meaning ‘marrow’. Together with the suffix ‘-itis’, which means inflammation, it describes inflammation of the spinal cord’s grey matter. Polio, which most commonly affects children, is also known as Infantile Paralysis.

Hepatitis A is also referred to as Infectious Hepatitis, Epidemic Hepatitis, Epidemic Jaundice and Catarrhal Jaundice.  

Polio

Persistent and frequent outbreaks of Polio in the late 19th and early 20th centuries meant that it became one of the most feared diseases in the world at that time. By the 1950s, the virus could be found anywhere in the world and would kill or paralyse more than half a million people every year. The worst recorded Polio outbreak in the United States in 1952 killed more than 3,000 people.  

Despite the development in the 1950s of highly effective vaccines, by 1988, when the Global Polio Eradication Initiative (GPEI) was launched by the World Health Organization, Polio was endemic in 125 countries worldwide and was still paralysing almost 1,000 children every day. 

Since the GPEI’s launch, there has been at least a 99 percent reduction in Polio cases. But eradicating the disease—something that has only ever been achieved with one other human disease, Smallpox—remains a challenging task.

Polio outbreaks are often a feature of war and conflict, where the displacement of people or the destruction of health and sanitation systems allows the virus to take hold and spread. A devastating civil war and humanitarian crisis in Syria since 2011 has allowed Polio to begin spreading again there, despite the disease having been wiped out of the country in 1999.  

Most recently, in August 2024, the WHO announced a plan to send 1.2 million polio vaccines to the war-torn Gaza Strip after the virus was detected in wastewater.  

Hepatitis A 

Hepatitis A occurs both sporadically and in epidemics all over the world. Large outbreaks of the disease are often related to contaminated food or water and can erupt explosively. One such epidemic in the Chinese city of Shanghai in 1988 was linked to the eating of raw clams and affected about 300,000 people, killing at least 47 of them.  

Between 2016 and 2023, 33 states in the United States reported Hepatitis A outbreaks that were spreading through person-to-person contact. These outbreaks have so far caused almost 45,000 infections, with thousands of cases of severe illness and more than 420 deaths.  

The work of disease defence specialists against Polio has been one of the greatest successes of all global efforts to combat viral infections in people, arguably second only to the total eradication of the Variola Smallpox virus in the 1980s. 

The renowned American virologist Jonas Salk developed the first successful Polio vaccine — the Inactivated Poliovirus Vaccine or IPV—in 1955 in a breakthrough that, according to his biographer, “was a folk victory, an occasion for pride and jubilation”. Together with another vaccine developed by the scientist Albert Sabin a few years later called Oral Poliovirus Vaccine or OPV, Salk’s work made it possible to put a stop to the crippling and deadly Polio epidemics that had swept through countries across the world for centuries. 

A highly effective vaccine called Vaqta against Hepatitis A was developed by the great vaccinologist Maurice Hilleman—sometimes referred to as “the most successful vaccinologist in history”—and approved for use in Europe in 1991 and in the United States in 1995. The vaccine is effective in around 95 percent of cases and provides protection from infection for at least 20 years, and potentially life-long. 

There is currently no vaccine against common cold infections caused by the Rhinovirus subgroup of the Picornavirus family. Scientists say this is most probably due to two main factors—one, there are more than 150 different Rhinoviruses that cause common colds (as well several more in other viral families such as the Coronavirus Family), and two, infections usually produce very mild and short-term symptoms that clear up without treatment.