Eight years after the last outbreak in 2005, polio is once again ravaging the Horn of Africa.
Since May health authorities have reported 191 cases: 174 in Somalia, 14 in north-eastern Kenya and three in Ethiopia. The outbreak appears to have been made worse by the years of war and government failure in Somalia, where large numbers of children have never been vaccinated against the disease.
"Already we've had more than 170 children suffering, which is 170 too many for an easily preventable disease," says Dr Hamid Jafari from the Global Polio Eradication Initiative (GPEI), the multinational body charged with dealing with the disease.
The vaccination response has been swift, with international aid agencies and local authorities coordinating mass campaigns in many parts of southern Somalia including the Banadir region and the Dadaab refugee camp for Somalis in Kenya, a sprawling semi-permanent home to the world's largest number of refugees - almost half a million - displaced by Somalia's 20-year civil war.
The GPEI has described the response as "rapid and aggressive". A fifth round of vaccinations concluded the last week in September. In Somalia, 3.4m children have been targeted. In some cases children up to ten years old and even adults have been given the "two drops" oral vaccine.
The epicentre of the disease in Somalia has been the capital, Mogadishu, in Banadir region, which from 2007-11 was under the control of the radical Islamist group the Shabab.
Since it fled the capital in late 2011 to its strongholds about 50kms away in south-central Somalia, the health system has not recovered enough to deal with this outbreak.
"It's very sad. I'm seeing lots of cases of paralysis and some of these children will die," says Dr Lul Mohammed, head of paediatrics at Banadir General Hospital, one of Mogadishu's oldest health facilities.
The hospital has managed to keep operating throughout Somalia's years of crisis. Dr Mohammed first started working there in 1988 and has seen several polio emergencies come and go. "If these children had just received two small drops their entire lives could have been very different," she regrets.
Poliomyelitis is a virus transmitted by faecal to oral contact, often through sewage and wastewater. In about 1-4% of infections it leads to some form of paralysis. Occasionally children die from respiratory failure.
Thousands of children carry the virus but show no signs of infection.
There is no known cure, but since 1988, when the Global Polio Eradication Initiative was launched, the disease had been largely brought under control through vaccinations.
Since then some 2.5 billion children worldwide have been immunised, and the number of cases of the disease has dropped dramatically - from about 1,000 children a day hit by paralysis in 1988 to about 2,000 cases reported in 2009.
However, the campaign to eradicate polio globally has been hampered by resistance to the vaccination in Pakistan and Nigeria, which has allowed the disease to continue spreading.
The 2005 outbreak in the Horn was connected to failure to vaccinate in Nigeria. Today the disease remains endemic in Nigeria, Afghanistan and Pakistan.
Faisa Abdullahi, eight years old, lives in the Dadaab refugee camp. She was a baby when the last outbreak hit in 2005, affecting 229 people in Somalia.
The disease has paralysed her limbs. "Sometimes my legs are very sore and I can't stand up. I have to walk with a stick," she told UNICEF, the UN's children's agency, earlier this year. "Other kids at school are not nice to me because of that. They don't understand what it's like for me to not be able to walk."
There is no doubt that the resurgence of polio in Somalia has been made worse by the absence of state institutions. After civil war broke out in 1991, the country had no functioning central government for more than 20 years.
Millions of people fled their homes in the fighting and health services were run into the ground, leaving large numbers of children without immunisations.
Although the Shabab was chased from the capital after a series of military defeats in late 2011, paving the way for the return of a new government formed in August 2012, they have retreated to strongholds in the Shabelle areas in the south-central region.
The Shabab has banned UNICEF and other UN agencies from operating there, leaving at least half a million children who cannot be reached. The French medical charity, Doctors Without Borders, also announced last August that it would pull out of Somalia.
"This area contains the largest pool of unvaccinated children anywhere in the world," says Susannah Price, UNICEF's chief spokeswoman on Somalia.
UNICEF and the GPEI are keen to emphasise that the new Somali government has taken vaccination seriously in the areas it controls. The president, Hassan Sheikh Mohammed, and the prime minister, Abdi Farah Shirdon Said, both took the oral vaccination in front of television cameras when the campaign was launched.
The government has only had one year to establish its authority, however, and the country is still struggling to cope.
"UNICEF and WHO [World Health Organisation] have organised under the leadership of the Somali government but the government are [sic] still lacking in funds and trained medical staff," Ms Price says.
For Dr Mohammed, the years without leadership have meant a whole generation has grown up without learning about the importance of childhood immunisations.
"Even in Mogadishu where the government is in control we've had our vaccination centres open all day but people just don't come," she says. To tackle this problem, teams are sent door-to-door to search for children. But this is costly and households are often missed.
"Some families still believe rumours that this is a Western plot that will make their children sick and they sometimes refuse to let the health teams in," says Dr Mohammed.
"One mother really sticks in my mind. She came with her children, one of them was sick with the disease. She desperately wanted the vaccination but her husband refused. There was nothing I could do."
Dadaab refugee camp in north-eastern Kenya is just 100km west of the Somali border and close to Banadir region. Somalis are a highly mobile nomadic community and it appears that this has helped polio to proliferate. Large numbers of people crossed the border into Kenya during the 2011 famine.
Kenya has had an easier time dealing with the disease as much of this refugee population lives in the five Dadaab camps where the UN's High Commissioner for Refugees (UNHCR) has more than 20 years of experience in public health campaigns.
Since May there have been four vaccination campaigns targeting some 4.9m children across Kenya.
The UNHCR has credited the Kenyan government for also offering the "two drops" to children in the neighbouring north-eastern communities of Wajir and Garissa districts to try and prevent the disease from spreading further.
"Close to 100% of the refugee population has been vaccinated with no major problems encountered," says Dr John Burton, a UNHCR public health official.
"Refugee leaders, religious leaders and other prominent community members have been very cooperative in spreading messages."
It may well be that these rapid immunisation campaigns have helped to stop this outbreak from reaching its full potential. GPEI claims that the number of cases has peaked. Dr Mohammed in Mogadishu notes that in the first few weeks of September she has seen only two cases, compared with about 30 in July.
But weak governance in the region may still undo this hard work if inoculation teams are unable to reach the estimated half a million unvaccinated children. Cross-border vaccination transit centres, which respond to the community's nomadic lifestyles, are critical, Dr Jafari says.
Some 10,000 children a week are being treated at 69 centres set up by the GPEI on the Somali/Kenya border, offering hope for families trapped in the Shabab-controlled areas.
"If we don't tackle the problem we will see this outbreak having a much longer tail than would normally be expected," Dr Jafari says. "We may well not see the back of this outbreak for another two years."