Immunodeficiency-related vaccine-derived Poliovirus isolated from the child and his father confirmed iVDPV type 1.
Published Jul 31, 2024 | 7:00 AM ⚊ Updated Jul 31, 2024 | 7:00 AM
A person from Kerala infected with Vaccine Derived Poliovirus from his child.
Since the Global Polio Eradication Initiative (GPEI) was launched in 1988, there has been a reduction of over 99.9 percent in polio cases, and wild poliovirus (WPV) types 2 and 3 have been eradicated.
In March 2014, India was certified as polio-free by the Regional Polio Certification Commission.
However, a rare and unprecedented case has emerged from Kerala, where a child transmitted Immunodeficiency-Related Vaccine-Derived Poliovirus (iVDPV) to his father.
However, the child succumbed to Severe Combined Immunodeficiency (SCID).
A study published in the Vaccine journal details this case. A seven-month-old male from Kerala received the oral polio vaccine (OPV) at birth and again at 20 weeks. Four stool samples collected at four-week intervals tested positive for iVDPV type 1. The child’s father, a 32-year-old asymptomatic male, was also found to be excreting iVDPV.
The discovery was conducted by ICMR-National Institute of Virology, Mumbai Unit; ICMR-National Institute of Immunohaematology; and the World Health Organisation India.
Government Medical College Hospital Kozhikode, a major teaching hospital in North Kerala, participated in the study from the beginning
According to the researchers, a 7-month-old male child from Malappuram district, the third child of non-consanguineous (not having common ancestors) parents, presented with persistent pneumonia for two months.
His growth parameters and developmental milestones were normal. The child received two doses of the oral polio vaccine (OPV) — one at birth and another at 20 weeks.
Investigations revealed lymphopenia — a lower-than-normal number of lymphocytes (a type of white blood cell) in the blood — and he was suspected to have Severe Combined Immunodeficiency (SCID), a rare genetic disorder characterised by the absence or malfunction of T and B lymphocytes.
This leads to a severely compromised immune system and increased susceptibility to infections.
“According to the iVDPV Phase I study protocol, his first stool sample was tested for poliovirus infection after the diagnosis of inborn errors of immunity (IEI) in July 2022, which yielded iVDPV type 1. The second, third, and fourth stool samples, collected four weeks apart, were also positive for iVDPV type 1,” said the researchers.
Immunodeficiency-Related Vaccine-Derived Poliovirus (iVDPV) refers to polioviruses that have mutated from the oral polio vaccine (OPV) strains in individuals with primary immunodeficiency disorders.
These individuals cannot clear the virus from their bodies, leading to prolonged shedding and potential transmission.
The oral polio vaccine contains weakened (attenuated) polioviruses that replicate in the intestines to stimulate immunity. In people with compromised immune systems, these vaccine-derived viruses can mutate over time instead of being cleared. As a result, the virus can persist and continue to replicate.
People shedding iVDPV can potentially spread the mutated virus to others, posing a risk of polio outbreaks, particularly in areas with low vaccination coverage.
iVDPV is usually detected through regular polio surveillance systems that analyse poliovirus from stool samples. Genetic sequencing is used to distinguish iVDPV from wild poliovirus and other vaccine-derived polioviruses.
According to the country’s emergency preparedness and response plan, the information about the iVDPV case was shared with ICMR Delhi, the Ministry of Health and Family Welfare, the South-East Asia World Health Organisation (WHO-SEARO), and the WHO headquarters on 1 August, 2022.
Researchers began an epidemiological investigation within 48 hours of the iVDPV notification.
This investigation, conducted 2 August to 5 August, 2022, included assessing population immunity for polio, conducting active case searches in the community and health facilities for any missed cases of Acute Flaccid Paralysis (AFP) — a sudden onset of weakness or paralysis often due to viral infections like poliovirus in the last six months — and collecting stool samples from contacts.
“A total of 89 percent of children aged 24–59 months had received three doses of OPV. Neither the families nor the 33 health facilities visited reported any AFP cases in the last six months,” said the researchers.
115 stool samples were collected from the community and tested for poliovirus. Of these, 114 samples were negative for iVDPV.
“However, the child’s father, an asymptomatic 32-year-old male, was found to be excreting iVDPV type 1. In contrast, the mother’s stool sample, as well as those from other family members, were negative. The father, who was involved in providing care including changing diapers, had close contact with the child and the family’s two other young children,” the researchers reported.
iVDPVs isolated from the SCID child and his father were characterised by Sanger sequencing, confirming them as iVDPV type 1.
The child underwent haploidentical hematopoietic stem cell transplantation (bone marrow transplantation) with cells from his father.
However, two days later, he developed a fever, breathlessness, and watery diarrhoea. A chest X-ray suggested right upper lobe collapse with pneumonitis — inflammation of the lung tissue often caused by infections, radiation therapy, medications, or inhalation of irritants.
Four days post-transplantation, the child’s sensorium — his brain’s ability to process and interpret sensory information — worsened. His fever and breathlessness persisted, and his heart failed to pump blood effectively, leading to cardiogenic shock.
An ultrasound of his heart showed that the left ventricle, the main pumping chamber, was not functioning well. He was put on a ventilator. Tests including an ECG and troponin I levels indicated severe inflammation of the heart muscle (myocarditis).
By day 10 post-transplant, the child’s body began to accept the new cells, and by day 14, 92 percent of his blood cells were from the donor.
Despite these efforts, the child passed away three weeks after the transplant.
“He developed cardiogenic shock with echocardiographic features of left ventricular dysfunction and was mechanically ventilated. His ECG and troponin I levels suggested severe myocarditis. Despite engraftment and 92 percent donor chimerism by day 14, the child expired three weeks following HSCT,” the researchers concluded.
Researchers say that getting rid of polio depends on quickly and reliably checking people with sudden muscle weakness and testing environmental samples like sewage and wastewater.
It’s also crucial to monitor people with weak immune systems from birth.
Early diagnosis of these immune system problems through newborn screening in countries that use the oral polio vaccine (OPV), making paediatricians aware of the risks of OPV in these patients, advising parents of affected children against using OPV or any live vaccine, and creating a national registry of these patients are important steps.
This will help ensure OPV is used wisely and avoid prolonged shedding of the poliovirus.
There are very few reported cases of vaccine-derived poliovirus (iVDPV) spreading to healthy people.
One study found an unknown source of iVDPV spreading in an unvaccinated community, infecting 23 children, including one with severe immune deficiency (SCID).
Another report from Spain described iVDPV spreading to healthy people. The case from Malappuram is one of the rare instances of iVDPV spreading from a child with immune issues to a healthy family member.
The Global Polio Surveillance and Action Plan 2022–2024 aims to integrate iVDPV monitoring with existing polio surveillance to ensure long-term sustainability after polio is eradicated.
Developing antiviral treatments for poliovirus and having a strategy to treat people with immune deficiencies who get infected with iVDPV is crucial.
This should be combined with better monitoring of these patients and global access to newborn screening to make polio eradication a reality and keep it that way. Expanding immune deficiency surveillance will help detect and track iVDPV shedding early, reducing the risk of its spread, said the researchers.
(Edited by Muhammed Fazil)
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