A groundbreaking research has shaken long-held beliefs about how poliovirus spreads, providing new insights into its transmission. Researchers, together with T. Jacob John from Christian Medical Faculty, Vellore, (now retired), Dhanya Dharmapalan from Apollo Hospitals, Navi Mumbai, Robert Steinglass, and Norbert Hirschhorn, have revisited the best way wild and vaccine-derived polioviruses are transmitted. Their findings, printed in Infectious Illnesses, present that poliovirus spreads primarily by the respiratory route, contradicting the generally accepted concept that it’s handed by faecally contaminated meals and water.
Based on Dr. T Jacob John, the worldwide marketing campaign to eradicate polio has centered on the concept the virus spreads by the faecal-oral route, with virus in meals and water which have been contaminated by sewage. . Nevertheless, he argues that proof clearly factors to respiratoy transmission as the primary means the virus strikes from individual to individual. This concentrate on contaminated meals and water, he provides, could have been as a result of prevalence of polio solely in low revenue nations the place sanitation/hgiene is poor, overlooking different key elements, akin to excessive delivery charges, the crowded residing situations and the best way adults and older kids socially work together with infants.
All through their analysis, the crew fastidiously examined historic information and performed a radical evaluation of how the virus spreads in communities. Their findings point out that specializing in the unsuitable transmission route has delayed polio eradication efforts. “We discovered no proof for transmission by contaminated meals or water from accessible research and observations, however all accessible info helps the respiratory route,” Dr. John defined. He additionally famous that this misunderstanding has led to the assumption that the reside oral polio vaccine (OPV) was important to interrupt transmission of untamed and vaccine-derived polioviruses. That explains why the eradication programme had been failing to totally cease transmission in lots of nations. In these nations, the vaccine efficacy of OPV is unacceptably low. In distinction, the inactivated polio vaccine has confirmed way more efficient, notably since the virus spreads primarily by the repiratory route. The vaccine efficacy of inactivated poliovirus vaccine (IPV) is great in these nations, simply as in others the place polioviruses had been eradicated utilizing IPV.
Dr. John additionally seemed carefully at previous research that linked polio to poor sanitation and water high quality. Whereas giving the OPV to kids can construct their immunity, by an infection by the oral route, he identified that this doesn’t mirror how the virus naturally spreads. Kids who obtain the OPV not often cross the virus on to others, which raises questions on whether or not the virus truly enters the physique by contaminated meals or water. “Sabin’s problem to show or disprove respiratory transmission remained unresolved, until now” Dr. John remarked, referring to the scientist who developed OPV, who had known as for extra analysis into whether or not poliovirus spreads by inhaling oral droplets.
The research strongly helps the transmission route as respiratory, which inserts higher with the accessible information. Dr. John emphasised that the continued reliance on the OPV has led to outbreaks of mutated vaccine strains, which may trigger polio sporadically and in outbreaks. These outbreaks are notably widespread in areas the place OPV is used, creating additional obstacles to eliminating the illness. Periodically the vaccine-derived virulent mutant viruses get exported to polio-free nations, making issues worse.
One of the crucial necessary findings of the analysis was the function of re-infections in immune people, which performs a vital half within the virus persevering with to unfold. Individuals who have been re-infected don’t present any signs, however they’ll nonetheless cross the virus to others, particularly in locations the place older individuals and infants are in shut contact with each other. Dr. John argues that this silent transmission amongst individuals who have already been contaminated, and later re-infected, is a significant cause why the virus continues to flow into, notably in areas the place vaccine protection is uneven or vaccine efficacy is just too low.
By figuring out droplet/aerosol transmission as the primary means poliovirus spreads, Dr. John suggests a transparent path ahead: switching from OPV to the IPV globally. In contrast to the oral vaccine, the IPV doesn’t infect and can not unfold between individuals, making it fully protected. “Solely the inactivated vaccine can be utilized within the polio-eradicated world,” Dr. John famous, urging well being authorities around the globe to hurry up the transition from the oral vaccine to the inactivated model with a view to totally get rid of polio.
Dr. John summarized the findings, stating, “The transmission of virulent polioviruses, whether or not wild or vaccine-derived, is thru the respiratory route, much like different contagious childhood illnesses like measles, rubella, and diphtheria.” This shift in understanding not solely has main implications for vaccination methods but in addition challenges long-standing public well being insurance policies which have centered on enhancing sanitation and water security as one option to cease polio.
Because the world continues to battle poliovirus, these findings could possibly be essential in shaping the subsequent steps towards eradicating the illness as soon as and for all. If international well being organizations comply with Dr. John’s advice to concentrate on respiratory transmission and swap to the inactivated vaccine, the long-awaited purpose of a polio-free world might lastly be inside attain.
Journal Reference
John, T. J., Dharmapalan, D., Steinglass, R., & Hirschhorn, N. (2024). “The respiratory route of transmission of virulent polioviruses.” Infectious Illnesses. DOI: https://doi.org/10.1080/23744235.2024.2392791
In regards to the Authors
T Jacob John (MBBS, DCH, FRCP(Edin), PhD, DSc) was educated in Paediatrics in India and the UK and in Paediatric Infectious Illnesses within the USA. Almost his total profession was within the Christian Medical Faculty, Vellore, India, the place he established India’s first Diagnostic Virology Laboratory in 1967. In 1978 the Laboratory was named the Nationwide Centre of Excellence by the Indian Council of Medical Analysis (Ministry of Well being, Authorities of India).
He popularised paediatric immunisations in India from 1967 (seven years earlier than WHO EPI was launched) and is popularly known as ‘Father of Immunisation’ in India. He was elected President of the Indian Affiliation of Medical Microbiologists (1984) and as President of the Indian Academy of Paediatrics (1999). He served on the Rotary Worldwide’s PolioPlus Committee and Well being-Starvation-Humanity Committee throughout 1984-1992. In 1992 he was honoured by the Medical Council of India because the ‘Eminent Medical Man of the Yr’ 1990. He retired from employment in 1995, and served as Emeritus Professor until 2000. He has printed 670 scientific papers in Medical Journals.
Dhanya Dharmapalan (MD, FIAP, FPIDS) is a Senior Advisor in Paediatric Infectious Illnesses at Apollo Hospitals, Navi Mumbai. She is the editor of 19 pediatric textbooks and co-authored with TJ John the e-book “Polio: The Eradication Imbroglio. The Illness and its Treatment” (2021)
Robert Steinglass (MPH, The Johns Hopkins College of Hygiene and Public Well being) has labored primarily for WHO and John Snow Inc., USA, for almost 50 years in almost 50 resource-poor nations, on strengthening immunisation packages, vaccine-preventable illnesses management, and new vaccine introductions.
Norbert Hirschhorn (MD), co-founder of John Snow, Inc., USA, helped develop the oral rehydration therapy for diarrhea, from bedside to nationwide packages. He was honored by the Dana and Pollin Foundations and Columbia College, and recommended by USA President Clinton as an ‘American Well being Hero.’
