The incident on April 17 has rekindled concerns about the safety of girls trying to receive an education in Afghanistan, with foreign forces preparing to leave the country by the end of 2014.
Human-rights advocates say the international community must ensure that access to education for girls in Afghanistan is not sacrificed as security is handed over to Afghan forces or as a result of any political settlement between Afghan President Hamid Karzai's government and insurgents.
Hafizullah Safi, the head of Takhar province's public health department, says investigators "strongly suspect" a water-supply tank at the Rostaq district's school for girls was poisoned by Taliban militants.
Safi says both the water supply itself and blood from hospitalized girls are being tested as part of an ongoing investigation by Afghan authorities.
"Their health condition is good now. They now only are showing signs of dizziness, fatigue, and exhaustion," Safi says. "The results of our investigation are not yet known. It has not been confirmed whether they were really poisoned or they were affected by hysterics after seeing, in their words, a man close to the water tank -- and fainted as a result.
"Perhaps that man did nothing and they fell ill due to a physiological effect," Safi continues. "We've taken blood samples of five girls, as well as samples of the water, and sent them along to Kabul to make clear whether it was poisoning or just a psychological condition."
Tawhidi says the parents of the sick schoolgirls are insisting on sending their daughters back to continue their education.
Listed In Stable Condition
Most of the hospitalized girls and teachers reportedly had been drinking from the school's water tank before becoming ill with symptoms that included severe nausea, headaches, and dizziness. But some reportedly fell ill only after seeing signs of sickness among the others.
By midday on April 18, Safi said 15 girls remained hospitalized with ongoing symptoms of poisoning. They were listed in stable condition.
The Taliban has not claimed responsibility for the incident. But Faizullah Tawhidi, a spokesman for the provincial governor of Takhar, said confirmation of poisoning would support investigators' suspicions of Taliban involvement because of the militia's opposition to schooling for girls.
"Of course, if it's proven that the water was poisoned or materials were mixed with it in order to damage the health of the girls, it is clear that it has been done by the enemies of Afghanistan, by those who do not want the children of the country to continue with their studies," Tawhidi says.
The Taliban has claimed responsibility for few incidents of violence in Takhar Province compared to other parts of Afghanistan. Tawhidi says, however, that Taliban militants appear to have infiltrated the province in recent years.
"Some secret networks of the Taliban are active [in the province]," he says, "and it is clear that they are trying to damage the society by resorting to different methods."
When in power in Kabul from 1996 to 2001, the Taliban regime banned education for girls. Taliban fighters have continued to target girls schools in the areas they control since then, resorting to rocket and mortar attacks, arson, poison, and even throwing acid in the faces of young girls. Taliban militants also have beheaded teachers who taught girls.
Afghan Education Ministry officials have confirmed there were at least 17 poison-gas attacks on girls schools in Afghanistan in 2010 -- including six attacks in Kabul -- that were thought to have been carried out by the Taliban or their sympathizers.
Skeptics downplayed many of those incidents, saying the wave of reported gas attacks was likely the result of mass hysteria. But doctors who treated victims said the use of poison was apparent and that such attacks have happened many times in Afghanistan.
In 2009, five Afghan girls briefly slipped into comas and nearly 100 other pupils needed treatment after an alleged gas attack against their school. Taliban sympathizers also were blamed for that incident.