Many health experts say that Africa's poverty and politics are to blame for diseases that in most developed countries are easily preventable.
International health agencies set out more than two years ago on a $2 billion campaign to stamp out the global threat of polio, the world's largest-ever health initiative. They believed they could eradicate the virus by the end of this year.
Not any more. In Africa, which has most of the world's polio cases, politics and armed conflict have played a major role in stalling the polio eradication program.
In northern Nigeria, government officials suspended the polio program two years ago after rumors spread that the vaccine caused sterility and AIDS. Health workers sent in to vaccinate children were taunted or stoned.
Although Nigerian health authorities have resumed the eradication program, the damage was done. Polio rebounded in northern Nigeria and spread to at least 17 other countries that had been polio-free.
Sudan is one of them. The number of confirmed cases of polio-induced paralysis in Sudan soared to 54, a dramatic and dangerous rebound in a country that had eradicated the virus just four years ago. Experts on polio say paralysis of limbs occurs in only one in 200 cases, leading them to believe that at least another 10,000 Sudanese were most likely infected by the polio virus. This fear prompted several U.N. aid agencies to issue warnings that Sudan was in the midst of a massive outbreak.
From the point of view of health workers, Sudan is a major crossroads between Africa and the Middle East. It's also a country where internal conflicts have been raging for more than two decades, creating conditions favorable for infectious diseases such as polio, AIDS, and tuberculosis. The fighting has led to a mass movement of people and crowded, festering camps for refugees and internally displaced people, known as IDPs. And what little health care infrastructure there was has been destroyed during the years of conflict. Not only that, the lingering volatility of regions like Sudan's western Darfur make it difficult, and even dangerous, for polio immunization teams to spread out across the country.
One of the polio campaign's worst fears was realized this year when Yemen, just across the Red Sea from Sudan, reported more than 400 cases of polio infection, nearly half the world's total cases, says Dr. Faten Kamel, the World Health Organization's regional director for the polio eradication program in northern Africa.
"By genomic sequence we can trace the origin of the virus. The situation in Nigeria and stopping of immunization activities by late 2003 due to unfounded rumors about the vaccine had a very bad effect on the whole region," she said. "The virus spread first throughout Nigeria, causing a lot of cases of paralysis, and then to other countries: from Nigeria to Chad, and then the virus spread inside Sudan, facilitated of course by the movement of populations, whether IDPs or returnees. And the virus moved with people from Sudan to Yemen."
A recent polio case was found in Ethiopia near the border with Somalia, raising fears that the virus might surface in a country that has no functioning government, much less a health care system.
The virus, which is spread mostly by feces, can lead to paralysis and death. It was eliminated from the developed world in the 1970s, but at least 300,000 cases remained in poorer countries.
In some ways, the polio eradication program, backed by the United Nations and the United States Centers for Disease Control, serves as a kind of template for other global health initiatives, including the campaign to fight AIDS, malaria and tuberculosis.
Patrick Bertrand, a spokesman for a Paris-based program called Massive Effort Campaign against AIDS, TB and Malaria in Africa, says fighting polio and these other diseases requires the full support of the people in regions where the diseases hit.
"This example of polio can be taken to other diseases," he said. "We know that, especially in TB or tuberculosis and HIV also, that mobilizing the community is key for the success of any health intervention. And I think that's one of the good results of this polio eradication campaign. I mean that when you involve the community at every level you have more chances to have success."
Many health experts say there is a link between AIDS and armed conflict in Africa, where 40 million people are infected with HIV. Infection rates among Africa's armed forces are staggering. Nearly a quarter of Ugandan soldiers tested positive for HIV, which is low compared with the Malawian army's 75 percent, or Zimbabwe's estimated 80 percent. South Africa's army, one of the best-maintained on the continent, found recently that more than 20 percent of its troops are infected with HIV and has stopped accepting HIV-positive recruits.
Those statistics worry health workers fighting the spread of AIDS, partly because African troops are often used in United Nations and African Union peace operations, including missions in Sudan, Burundi and the Democratic Republic of Congo. Their fear is that soldiers, sent in to protect vulnerable populations, are spreading the virus.
Paul Zeitz is the director for Global AIDS Alliance, a Washington-based nongovernmental agency that helps African communities fight AIDS.
"There's clear evidence that armed conflict and HIV are interlinked," he explained. "From the African continent specifically, we know that when there are conflicts where local populations are displaced and refugee situations emerge, that those environments become strong environments for increasing HIV transmission.
"African militaries have high rates of HIV infection," continued Mr. Zeitz. "When they're in operations there are problems at times where they get involved with sexual activity with local populations, with sex workers, rape increases in the those environments. We know time after time that that is leading to increased risk for HIV transmission."
The first massive outbreak of AIDS on this continent was in southern Uganda during the 1970s, where the spread of AIDS coincided with a Tanzanian-backed rebel invasion that toppled that country's reviled dictator, Idi Amin.
The leader of that invasion, Yoweri Museveni, went on to become the country's president. He helped mobilize the country against AIDS in a campaign that became a model for other African nations. The country's HIV infection rates dropped from 30 percent a decade ago to about six percent today.
Mr. Zeitz says that most African leaders have shown a willingness to step up to the AIDS challenge, but that many African governments, being short of cash, have been unable to follow through on their pledges to combat AIDS.
"African presidents in 2001 committed to providing 15 percent of their national budget into the health sector, in part to respond to the crisis of AIDS, TB, and malaria, and very few African governments are actually doing that," he added.
Yet, other African leaders have been slow to acknowledge the AIDS virus. South Africa has more than five million people infected with HIV. Still, President Thabo Mbeki, who rarely talks about AIDS, has suggested that other factors other than HIV cause the disease.
Recently, Uganda's President Museveni has started backpedaling on at least one aspect of his country's AIDS-fighting ABC platform - Abstinence; Be faithful, use Condoms. Critics say the Ugandan president is emphasizing abstinence and faithfulness-in-marriage programs, more in line with what many health experts see as a major shift in U.S. funding priorities for fighting AIDS in Africa.
But in Uganda, as in much of Africa, many women and girls are unable to choose when they want to have sex, or with whom. And many health workers say that on much of the continent even marriage is a risk factor for AIDS.