Polio eradication methods, lessons from Nigeria

Polio eradication methods, lessons from Nigeria

Andrio Adiwibowo, Jakarta

During the past several weeks, Indonesia has been shocked by
the return of the polio virus to Java. The small initial outbreak
that was centered in the Sukabumi region in West Java has been
reported to have spread to areas nearby. Many researchers are
considerably concerned about the reoccurrence of polio in
Indonesia, on top of the other numerous deadly diseases that the
country is hit with almost every year, including dengue fever,
avian flu, and SARS. For a little more than a decade, Indonesia
had thought it had eradicated polio successfully.

How did this illness, caused by the poliovirus, reoccur in
Indonesia again? This issue has challenged researchers to address
the following questions. First, is it possible that within
several decades the virus has mutated and into a new type of
virus, which has high resistance against the available cures or
perhaps the old virus type has been replaced by a wild polio
virus that has not been detected yet?

Meanwhile, certain local communities living in rural areas are
not as concerned with sanitation issues as their city
counterparts, or do not have access to proper hygienic
facilities, and this could promote the rapid spread of the virus.
Village people tend to defecate in the waterways, while they also
use the same canals or rivers for household purposes; including
water for drinking and washing. Human feces can contain millions
of viruses. It is also possible that the human resistance and
antibody systems in the present generation are less strong than
in previous generations. As a result, people become more
vulnerable to the virus.

The prevention -- the polio vaccination -- plays a vital role
in promoting the success of polio eradication. However, we should
be concerned about the possibility that a failure to vaccinate or
even a vaccine failure has taken place. There could also be
problems with how the vaccine was administered to patients --
were they given the right dose or not?

The presence of a mutated virus or one of an undefined new
type such as a wild poliovirus strain is one of the significant
obstacles to polio eradication around the world. Many researchers
have found new wild polioviruses across the Africa and Asian
continents. For example, a new wild virus that has significantly
different genetic material than the common Asian polio virus has
been found in a particular area in the Mekong River near Vietnam
and Cambodia.

Recently, it was assumed that the polio outbreaks in Indonesia
were caused by a wild virus that originated from the African
country of Nigeria. That country, along with India and Pakistan,
is known to be a poliovirus reservoir. Last year, a strain of the
virus was found firstly in Kano State, Northern Nigeria. The
infection spread rapidly into neighboring countries, such as
Burkina Faso, Chad, Ghana, and Togo.

The return of polio in Nigeria surprised the global health
authorities, who had earlier categorized the eradication campaign
there as remarkably successful. According to the latest research,
the most common cause for the persistence of polio disease in
developing countries has been the failure of routine immunization
programs to provide the correct dose of the poliovirus vaccine to
a high proportion of the countries' infants; not the presence of
any new wild polio virus. This vaccination error was identified
in Nigeria. The leaders of public health facilities in the
country had failed to provide children the right dosage, which is
10 doses of the vaccine per infant.

However, a more worrisome pattern of disease can be attributed
more to vaccine failure than a failure to vaccinate. The Oral
Polioviruses Vaccine (OPV) has been found to provide less
effective prevention than the Inactivated Poliovirus Vaccine
(IPV). Today, national leaders of public health have no
opportunity to make an informed choice between the OPV and the
inactivated poliovirus vaccine (IPV). In fact, they tend to use
the OPV exclusively. Unfortunately, the routine use of OPV could
mean patients risk the vaccine-associated paralytic poliomyelitis
(VAPP) disease.

While it is believed that discontinuing OPV activities could
lessen the threat of VAPP, any delay in the changeover to the IPV
could still yield negative outcomes. Halting an OPV program will
increase the risk of vaccine-derived polioviruses (cVDPV)
emerging that acquire wild virus-like properties and may cause
further outbreaks of polio.

The IPV is currently the best vaccine to supersede the OPV.
However, at the moment the IPV option is restricted to developed
countries. The price of the drug, which is too costly for most
Third World nations, and their local officials' lack of large-
scale field experience in administering the vaccine -- are the
two major barriers to its use.

Polio eradication strategies should emphasize scientific
investigations that focus more on the virus inventory, isolation,
and identification in order to find new wild polioviruses.
Furthermore, this research must be accompanied by extensive
studies that yield effective and affordable vaccines.

The world demands a vaccine that can moderate the threats of
Vaccine-Associated Paralytic Poliomyelitis and Vaccine-Derived
Polioviruses, and IPV is certainly the answer. However, with the
threat of new mutations, the administration of IPV alone will not
be sufficient to the achieve global eradication of wild
poliovirus transmissions, especially in developing countries.

The first step is to improve the manufacturing capacities in
the developing world so that these countries can produce the IPV
at a low cost. The next aggressive approach is a policy shift to
promote the use of IPV as the exclusive vaccine during national
immunization campaigns.

Hopefully, the decision-makers in public health here can learn
a valuable experience from Nigeria and make the right decision
resulting in a sustainable polio eradication plan.

The writer is a researcher in the Public Health and Virology
Department at the University of Indonesia, Jakarta. He can be
reached on andrio7897@yahoo.com.