The report that a three-month old boy from Tuaran, Sabah was admitted to the intensive care unit with poliomyelitis or polio, was shocking.
This was the first reported case in 27 years in Malaysia. The last documented case was in 1992 and the last outbreak was in 1977, with 121 cases due to wild polio.
The World Health Organization (WHO) declared Malaysia polio-free in 2000.
Polio, a viral disease, usually affects children below five years.
It is spread by direct contact, primarily through the faecal-oral route and less often, through contaminated water or food leading to multiplication of the virus in the intestines. The virus attacks the nervous system and causes irreversible paralysis, usually of the legs, in one in 200 infections.
Of those paralysed, 5-10% die when their breathing muscles are affected.
There are three types of wild polio (I, 2 and 3).
According to WHO, there was global eradication of the type 2 virus in 1999 and no case of type 3 reported since the last reported case in Nigeria in 2012.
The WHO launched its global polio eradication initiative in 1988.
Oral polio vaccine (OPV) has been administered to nearly three billion children globally with more than 10 billion doses.
This led to the prevention of 13 million cases of polio with a more than 99% decrease in wild polio from an estimated 350,000 cases in 1988 to 33 in 2018.
In Malaysia, the OPV was incorporated into the national immunisation programme earlier in 1972. OPV was replaced with the combined five-in-one diphtheria, tetanus, pertussis, injectable inactivated polio and haemophilus influenzae b (DTaP-IPV-Hib) vaccine in 2008.
The advantage of the injectable inactivated polio vaccine is that there is no virus in the child’s intestine.
OPV contains a weakened virus which is cheap and easy to administer.
Upon administration, the weakened virus multiplies in the child’s intestine for a limited period and stimulates antibody production. During this period the OPV is also excreted in the faeces.
With inadequate sanitation, the excreted vaccine-virus can spread to the immediate community before eventually dying out.
Rarely, when a population is markedly under-immunised, the excreted vaccine-virus can persist for a longer period of time. The longer the excreted vaccine-virus survives, the more likely it will undergo genetic change.
Very rarely, the excreted vaccine-virus can change into one that regains the capability to cause paralysis. This mutated virus is called circulating vaccine-derived poliovirus (cVDPV).
cVDPV takes at least 12 months to occur in a population that is vulnerable to wild polio or cVDPV because there is no immunisation or under-immunisation. The latter occurs when routine or supplementary immunisation are poorly administered.
In short, the root cause of cVDPV is low immunisation coverage and not the polio vaccine itself. If the population is fully immunised, they will be protected against wild polio and cVDPV.
Since WHO started its global polio eradication initiative in 1988 up until 2018, there have been 24 cVDPV outbreaks in 24 countries, resulting in less than 760 vaccine-derived poliovirus (VDPV) cases reported.
The Philippines Department of Health (DOH) declared a polio outbreak in September 2019, with two cases caused by vaccine-derived poliovirus type 2 (VDPV2). Environmental samples taken from a waterway in Davao a month prior to the discovery tested positive for VDPV2. In addition, VDPV1 was also isolated from environmental samples collected in Manila in July and August 2019.
The WHO estimated that the risk of further spread within the Philippines is high due to “limited population immunity (coverage of bivalent OPV and inactivated polio vaccine (IPV) was at 66% and 41% respectively in 2018) and suboptimal AFP (acute flaccid paralysis) surveillance.”
The WHO announced that the case in Sabah is a “rare strain of poliovirus called circulating vaccine-derived polio (cVDPV) Type 1. These polio viruses only occur if a population is seriously under-immunised. The Sabah polio case is genetically linked to the ongoing poliovirus circulation in the southern Philippines.”
Sanitary conditions in rural Sabah, particularly among the migrants from neighbouring countries, have been a health and social issue.
A portal report from the village of the polio victim is very disturbing.
A Kampung Damat resident was quoted as saying: “Although all of us are supplied with treated water, many house owners have to dig up pits to manage their bodily wastes.”
No less disturbing is the claim by the Sabah Education and Innovation assistant minister that the Health Ministry ignored the United Nations Children’s Fund’s (Unicef) call to vaccinate the undocumented population in Sabah for free.
Figures from the Home Ministry state that there are some 500,000 undocumented persons in Sabah and 95% of the children from this group had not been immunised.
The reported response from the then Health Minister was that “a fee of RM40 for registration and additional RM40 for one vaccine would be charged to non-citizens and the undocumented.”
The Philippines outbreak was reported about two months before the Sabah case.
Given the proximity of Mindanao to Sabah and the mobility of the populations, the question arises as to whether the Health Ministry responded to this red flag.
Was preventive vaccination of all children in Sabah considered during this window of opportunity?
The policy question of migrant’s access to public health preventive measures have to be addressed.
The cost of vaccination is nothing compared to that of having a child in the intensive care unit, care after discharge and the costs incurred in preventing other case(s) from occurring.
The Health Ministry’s data states that polio immunisation coverage in 2018 was 100%.
Documented foreigners in Malaysia increased from 1.7 million to 2010 to 2.2 million in 2017 with an estimated two to four million additional undocumented ones at the end of 2018.
Should the Health Ministry’s data not include the immunisation rates of foreigners who comprise just under 10% of the population so that the data is accurate?
The Philippines DOH attributed their outbreak to low immunisation, lackadaisical monitoring and poor sanitation.
What does the Health Ministry attribute the virus’ return in Malaysia to?
Vaccination has been one of the most effective public health interventions which saved lives and enhanced health. Only clean water has performed better.
Vaccines have eradicated smallpox and nearly eradicated polio. However, vaccine preventable diseases have not all disappeared.
The WHO states” “As long as a single child remains infected, children in all countries are at risk of contracting polio. Failure to eradicate polio from these last remaining strongholds could result in as many as 200,000 new cases every year, within 10 years, all over the world.”
Dr Milton Lum is a past president of the Federation of Private Medical Practitioners Associations and the Malaysian Medical Association. The views expressed do not represent that of organisations that the writer is associated with. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.