Deaths from measles are declining worldwide, but Nigeria, India and Pakistan need to step up immunization to beat the lethal virus, U.N. agencies said on Friday.

The World Health Organization (WHO) and U.N. Children’s Fund (UNICEF) said the world was “on target” to halve global deaths from measles by the end of 2005 from 873,000 in 1999.

Deaths from the contagious disease, which can be prevented by vaccination, have already fallen by nearly 40 percent since 1999, though 2004 figures are not in yet, they said in a joint statement.

“We are winning the fight against measles,” Jean-Marie Okwo-Bele, director of WHO’s immunization and vaccines department, told a news briefing.

Only a decade ago, measles killed millions of children each year, and left many with life-long disabilities such as blindness and brain damage, the WHO said.

Bradley Hersh, the WHO’s global measles coordinator, said it is targeting 45 countries, mostly in sub-Saharan African and south Asia, where measles immunization coverage averages only 60 percent.

“To maintain gains in mortality reduction, efforts are needed to strengthen routine immunization services in priority countries. The focus now is to increase support to the large priority countries - Nigeria, India and Pakistan,” he said.

About half of all measles deaths last year occurred in the three countries, Hersh said.

Nigeria, India and Pakistan, where the crippling poliovirus is also taking a toll despite a global eradication campaign, lack strong health care systems and routine vaccine coverage, Hersh said.

The likely next goal would be to reduce mortality by 90 percent by 2010, compared with 1999, according to Okwo-Bele.