Thousands of Nepalese survivors are at risk of another catastrophe after a magnitude 7.8 earthquake hit the South Asian country on April 25.

As the hurt and the hungry crowd makeshift shelters, food and water become scarce; sanitation poor, and life on the streets makes the perfect breeding ground for infectious disease.

Dengue fever, malaria and Japanese encephalitis: All three are already in the country, and pools of standing water from the quake will attract mosquitoes to transmit the illnesses.

That water, and other sources being used for drinking, is contaminated, according to medical expert Dr. Nikhil Joshi, who is returning to Nepal in June to treat survivors.

"There will be water-borne diseases like typhoid fever and things like bacterial diarrhea could be another huge problem," he said while speaking to the CBC's Marcy Markusa on Information Radio.

That is, when there is water at all.

"There's a straight up lack of [it] ... So, that causes dehydration, and you can die of dehydration," Joshi said.

Tuberculosis is rampant in Nepal, according to Joshi, and spreads quickly through coughing and sputum.

Cholera crop graphic

According to Dr. Joshi, cholera is an infection that may become a problem in Nepal following the April 25 earthquake. This graphic, created by Corinne Rikkelman for CBC News, illustrates that cholera is transmitted when vibrio cholerae, the cholera bacterium, enters the human body through contaminated water. The bacteria release toxins, which prevent human intestines from absorbing water. Diarhhea and dehydration result, and if left untreated, the infection can be fatal. (Corinne Rikkelman for CBC News)

On Friday, the quake's death toll hit 6,260 (including those who died on Mount Everest), and the Associated Press reported the Nepalese government was giving the equivalent of $1,000 U.S. to families for each life claimed.

Joshi says the aftermath could kill more people than the disaster that came before it.

"Put a bunch of people together who are sick, tired and malnourished and you've got a serious problem," he said.

"Sadly, this isn't unique. After an epidemic, we often see outbreaks of infectious diseases."

Monsoon season — between June and August, and usually lovely in South Asia — will make it worse: Rain will fall over those who used to live in 130,000 homes that were destroyed.

"Getting shelter before then is a huge necessity, and if people don't ... there's the risks of exposure, including hypothermia," Joshi said.

"The rain and thunderstorms can cause landslides. The landslides can make it harder for rescue teams to reach people remotely as the roads often get washed out. Villages that barely survived could easily be wiped out."

In Nepal, the catastrophe's weight is pressure on top of a health care system that never had a reliable foundation.

"Accessibility to health care for the average Nepalese citizen at the best of times was problematic," Joshi said.

According to him, Nepal has around 70 hospitals, and the system is a combination of private and public care.

While numbers can portray the extent of tragedy — 6,000 dead, 30 metric tons of medical supplies delivered, a four-month-old baby boy found alive, millions of raindrops to fall during monsoon season — Joshi says the figures that come after the quake, including the number of people affected by disease, complete the picture.

"We often look at things in terms of death toll from a disaster," he said.

"But that really only tells a fraction of the story."