What is in a gutter? There is a lot in sewage that could provide vital clues to crippling diseases like polio, particularly for a country like India, which has just successfully controlled this major health menace

By Syed Akbar
Hyderabad:  What is in a gutter? There is a lot in sewage that
could provide vital clues to crippling diseases like polio,
particularly for a country like India, which has just successfully
controlled this major health menace.

Researchers will now scour the sewage in select cities to find out if
the poliovirus thrives in the dirty waters. India had last reported a
polio case 18 months ago and it still needs a few more months to
qualify for the polio elimination certificate. If no polio cases are
reported for another five years thereafter, the World Health
Organisation will declare polio as eradicated from India.

Poliovirus is shed through faeces. Even the oral polio vaccine, which
is a live but attenuated virus, also causes shedding of the virus
through faeces. Therefore, analyzing sewage samples reveals whether
the virus is circulating in the drains. Since transmission of
poliovirus is through faeco-oral route, any contamination of drinking
water may lead to resurface of the problem. Apart from zero clinical
cases of polio, zero positive results from sewage are also important
to win the war against polio.

Says infectious diseases expert Dr Suneetha Narreddy, constant
monitoring is important for India as the country is in the phase of
eliminating polio. “The virus shed due to oral polio vaccination may
mutate to become wild virus. It is time the government should think of
switching over from oral polio vaccine to injectable polio vaccine. In
IPV there is no shedding of virus,” she points out.

Teams from WHO will collect sewage samples from different cities. They
will analyse them to find out if the poliovirus is present. Similar
samples collected last year from Delhi, Mumbai and other places did
not show the presence of the virus. Following this, the WHO removed
India from the list of polio endemic countries in February this year.

However, as a precautionary measure it will take up souring of sewage
in more cities to make it doubly sure that there is no poliovirus
circulating in the sewer lines. To begin with, the WHO is
concentrating on Punjab.

In a tweet on microblogging site, Twitter, on Monday the WHO said,
“Poliovirus is excreted in human waste. Sampling the sewage allows
health officials to see if the virus is circulating in a town”. In
another tweet, it said, “knowing where poliovirus circulates is
critical to vaccinating children in the area and ultimately
eradicating the virus globally”.

Authorities in Hyderabad have not yet received official message from
the WHO for sewage sampling for poliovirus. Says Dr D Shalini, chief
medical officer, GHMC, “we have not yet carried out sampling of sewage
for poliovirus. However, we do occasional testing of faecal samples
for acute flaccid paralysis in suspected polio cases.”

Presence of poliovirus in sewage reflects the status of sanitation in
a given city. Absence of the poliovirus in sewage means that there is
no danger. If it is present, chances of resurface are always there,
says Dr Suneetha.