Epidemics put on maths map

 MICK ROBERTS has a room with a view. An entire wall of his office is lined with books and on a whiteboard near the door are scrawled calculations and a network of dots and lines. It's a dreary day and a relentless mist clouds the outlook over Massey University's Albany campus where the professor works as a mathematical biologist.

Recently he received  further funding for his research. His specialist area  is using mathematical models to predict the spread of infectious diseases.

"I was working for the Ministry of Health on measles, the flu and Sars," he says. "In 1996 they asked me to do a model for measles transmission in New Zealand. I predicted an epidemic in 97."

His  computer models  capture the complex nature of our social networks, including the  workplace, schools and  public transport. His predictions of a measles outbreak were  correct. "Because of that they got a measles campaign in place so ...  were able to knock it on the head."

And of the recent measles outbreak here in Auckland? "It stemmed from imported cases. You can't safeguard against that, although a lot of people are vaccinated now," he says.

Measles is   highly contagious.

"Outbreaks tend to happen first in bigger cities. On average, one person with measles can pass it on to about 12, whereas with flu it's more like one to two."

He  points to a network written on a whiteboard. "The dots are people, the lines are the contacts they have with different people." Infected people are red,  the rest blue.

"Some people would pick it up, others wouldn't. It can be a case of chance. The most common way to spread disease is hand-to-mouth. Face masks are effective for this reason, because it stops people putting their hands in their mouth, not because of safeguarding against airborne diseases," he says, as I become conscious of keeping my hands in my lap.

Roberts says this method of mapping the spread of infectious disease was devised in the 1930s but was not looked at again until researchers at the Imperial College in London took on the theory in the 70s. Now health ministries  use mathematical mapping, collaborating with researchers at universities.

Roberts, whose findings have been published in several journals,  says he got into the work "by accident".

"I had finished my PhD in applied maths. Then I applied for a job modelling biological systems with the Ministry of Agriculture."

His first task was to help create a treatment programme to combat hydatid disease, a tapeworm he describes as a "nasty parasite" that travels between dogs and sheep. He helped determine the programme that protected dogs against the infection, which can kill  humans.

"Parasites are fascinating things," Roberts says, "but it's a good mathematical challenge that I like."

A coincidence  found Roberts  in Spain just as swine flu broke out there. He was  funded by the Health Research Council to analyse the 2009 outbreak of swine flu. "They were expecting bird flu but they ended up with swine flu. People are more closely related to pigs."

But bird flu is anticipated as the next epidemic the world will see and Roberts says the theory of a flu epidemic occurring every few decades is correct.

"Spanish influenza in 1918 and 1919 probably killed more people than the war did. It didn't start in Spain, though, it was called that because it was first reported there. It started in the United States, but they had censorship."

Through his Marsden Fund financing - awarded to top Kiwi researchers to explore their ideas - he hopes to create a better understanding of epidemics. "I hope to be able to relate the spread of epidemics in networks to the set of models that can be analysed mathematically for a better explanation of how epidemics spread."