POLIOMYELITIS, one of the silent killers of children in Cambodia, is on the verge

of being wiped out, say international health experts who are helping the Government

in a two-pronged offensive against the scourge.

"Another successful [series of] National Immunization Days (NIDs), we think,

should deliver something very close to a death blow to the virus," says World

Health Organization (WHO) technical officer David C. Bassett. Bassett has advised

the Ministry of Health in launching the up-coming immunization days set for February

11 and March 11.

According to a national health survey released by the United Nations Children's Fund

(UNICEF), polio - a form of paralysis caused by a breakdown of nerves in the spinal

column - is the most common cause of handicap among Cambodian children.

"Once the nerves in the spine are gone, they're gone forever," says Bassett.

Nevertheless, both WHO and UNICEF are confident that, if all goes to plan, the Ministry's

Routine or Extended Programme on Immunization (EPI) - boosted by the 1996 immunization

days - will lead to the elimination of the disease in Cambodia.

"We do not expect to get rid of polio this year, but we expect that by the end

of 1996, we are going to have a hard time finding polio here," says Bassett.

"We have, we are quite certain, less virus in circulation this year than we

did at this time last year. By next year, it's going to be gone."

Eradicating polio would be a remarkable achievement for the nation's health system,

which had fallen into complete disarray during the Pol Pot rule.

Despite the complications of reaching villages in the war-torn provinces, during

the 1995 immunization days, reports UNICEF, 1.8 million children - 95 percent

of the entire under-five population - were covered by the orally administered vaccine.

This year's drive is even more ambitious.

"We have organized almost 10,000 vaccination posts throughout the country,"

says Ly Nareth, director of the Polio Eradication Unit at the Ministry's National

Center for Hygiene and Epidemiology.

"Almost every village in Cambodia will have a vaccination post."

The posts will be manned by trained volunteer health workers who will handle the

4.6 million doses of polio vaccine, which comes in the form of droplets.

The Ministry of Health is aiming to immunize 1.84 million children this year. Financial

and technical aid for the 1996 immunization days is being given by the Japanese and

Australian governments, Rotary International, and other international bodies.

"The basic objective behind NIDs is to provide the polio vaccine to all susceptible

children at the same time, thereby denying the wild virus a host," says Bassett.

He also points out that man is the only host for the virus, and that the virus can

only survive outside its host for a period of two to three weeks.

"If you deliver the vaccine to every single susceptible child in the country

at once, you create a three to four week window during which the virus cannot find

a host," he says. "In theory, if you got to everyone at once, you should

knock it out in one shot."

There will also be a new twist to this year's immunization days: each child will

be given a dose of Vitamin A to prevent night blindness. Vitamin A also helps children

fight the complications arising from measles and diarrheal infections.

Riitta Poutiainen, Bassett's counterpart at UNICEF, welcomes the immunization days,

but stresses that the government's immunization program is equally important in fighting

polio.

To her, the immunization days are vital in eradicating the wild virus at the communal

level, but the "blanket immunity" conveyed through the monthly spaced doses

are not sufficient to provide complete coverage against the disease. To be fully

immunized against polio, she says, every child needs at least three doses of the

vaccine.

Poutiainen praises the success story of the Ministry of Health's long-term efforts

to immunize all Cambodian children under the age of one, not only against polio,

but also against diphtheria, measles, tetanus, tuberculosis and whooping cough.

"The major killers of children in Cambodia are, in fact, measles and neo-natal

tetanus."

The logistics of this Sunday's immunization day will largely be based on the infrastructure

of the Ministry's immunization program, which already exists at the provincial and

district level. It includes everything from provisions of cold-chaining equipment

- which keeps the vaccine refrigerated up till delivery - to motorcycles to negotiate

tricky roads in far-off areas.

"In 1995, very close to 80 percent of all children under one year were given

this protection through EPI in this country," adds Poutiainen. "It is a

major achievement, considering Cambodia's circumstances."

Although UNICEF normally holds multiple-vaccine immunization days in other developing

countries, it eventually complied with WHO and Ministry demands that the immunization

days be restricted to targeting of polio. UNICEF recognized that given the lack of

well-trained health workers in Cambodia, and the security situation in some provinces,

it would be extremely difficult to vaccinate against the other disease.

On top of this, explains Poutiainen, other types of vaccination that require the

use of syringes also carry the risk of adding to the prevalence of HIV and Hepatitis-B

infection in the country.

Both Bassett and Poutiainen agree that, taking into consideration the Ministry of

Health's target of ridding Cambodia of polio by the year 2000, the routine program

of immunization against polio and the immunization days would not be able to lick

the disease if they operated independently of one another.

"We could never eradicate polio by only doing routine vaccinations of under-ones"

says Bassett. "You have to do something like NIDs in addition to the routine

program to eradicate polio, but we would have a hard time eradicating the disease

only with NIDs too.

"A year ago, Cambodia was one of the most endemic countries in the world,"

he adds. "Now, it's considered to have one of the best anti-polio programs in

the region."