Essential medicines are becoming increasingly scarce in the capital, Antananarivo, and there are fears that people could start dying if the country's leadership crisis is not resolved soon.
After two bridges linking the capital to the rest of the country were destroyed on Tuesday, United Nations Development Programme Resident Representative Adama Guindo told IRIN the "readiness of clinics to deal with emergencies has deteriorated tremendously since the political crisis started".
"First it was the roadblocks and now the blowing up of the bridges. This means that important vaccines are not reaching the hospitals and clinics on time," he said, adding that many Antananarivo clinics were running out of antibiotics and anti-inflammatory medicines. There was also a shortage of polio vaccines, Guindo said.
News reports alleged that backers of embattled president Didier Ratsiraka destroyed the Miandriavazo bridge, 270 km southwest of Antananarivo, on the main road linking the western port of Morondava to Antsirabe.
Midi Madagaskara, a local newspaper which supports the opposition's self-declared president, Marc Ravalomanana, said a second bridge was later blown up at Antinafotsy, 250 km south of the capital. The bridge was on a road used as a detour by vehicles after a bridge at Fatihita - on the main road linking Antananarivo to Fianarantsoa - was destroyed on Friday.
The destruction of the two bridges means that all main roads used by trucks taking essentials to Antananarivo are impassable, forcing aid agencies to fly in vaccines.
The recent acts of sabotage are seen by analysts as a tactic by Ratsiraka supporters to isolate Antananarivo, where Ravolomanana has most of his support, and to force him to dissolve the "government" he installed in February.
Meanwhile, aid workers fear that should the three-month long crisis continue indefinitely, the most vulnerable groups in the country will be most affected.
"We are particularly concerned about the possible increase in cholera infections amongst the poorer communities. Cholera developed into an epidemic after the March 2000 floods. If the rains this year are anything like what we experienced in 2000, then we are in trouble because we will not have the medicines in time to help those people," Guindo said.
He also warned of a possible increase in the risk of HIV infections because contraceptives were running out in the country.
In an appeal to the Madagascan government last week, donor countries demanded that roadblocks set up to starve the capital of food and other essentials be lifted and that the transport system return to normal.
"The disruption of the transport system and the lack of fuel means that health workers are unable to get to emergency situations on time and people are dying unecessarily," Guindo told IRIN
Also on Tuesday, AP reported that a soldier loyal to Ratsiraka was killed in a confrontation with opposition. The soldier was allegedly trying to disarm members of the security forces supporting Ravalomanana in the town of Fianarantsoa, 300 km south of the capital.
Ratsiraka supporters set up roadblocks in February between Antananarivo and Toamasina, saying they would only take them down on the president's orders or Ravalomanana called off a general strike mounted to back his claims of vote-rigging in the first round of a presidential poll on 16 December.
Ravalomanana called off the strike two weeks ago, but has refused to enter crisis talks with Ratsiraka until the blockade is lifted. The president has ruled out any negotiation unless Ravalomanana agrees to a second round of elections.