Bill Gates believes the world can and must step up the fight against a group of little-known and long-neglected tropical diseases, that collectively do as much damage as HIV, malaria or tuberculosis.

In an exclusive interview with the Guardian, the founder and former boss of Microsoft said the money has to be found, even in the current difficult economic climate, for highly effective programmes, including the mass delivery of drugs that can prevent diseases such as schistosomiasis and trachoma.

"I think we'll be able to raise the money. It's kind of like vaccines – you'd feel awful if you didn't raise the money," he said. But, "it may take us a few years to get up to where we are doing all these mass drug administration programmes at the intensity we'd like to."

Everybody recognises the damage done by HIV, but few realise the burden of sickness and disability caused by the group of diseases identified by the billionaire philanthropist, which are transmitted mostly by parasites, flies and worms. One in six people globally is at risk. And by contrast with the big three, significant strides towards controlling some of the diseases are taking place.

"If this was one disease and the entire burden was attributed to one disease, it would be right up there with the big diseases," said Gates. "As a group … the human burden [in terms of disability] is pretty gigantic. I put this whole programme up there with what's going on with malaria, what's going on with TB, what's going on with HIV – it's something that people ought to be pretty excited about the progress that's been made."

Gates was speaking from Paris, where he was taking part in a meeting to look at the progress made against 10 neglected tropical diseases in the last two years. In January 2012, Gates convened an unprecedented meeting of the CEOs of 13 major drug companies – normally rivals – as well as global health organisations and governments in London, who all signed a declaration, pledging to do what they can to control or eliminate them.

Gates said he was "super-happy" with the progress so far. The pharmaceutical companies have increased their donations of existing drugs that can prevent some of the diseases and are helping to investigate potential new drugs for diseases where there are inadequate treatments.

"We're super-happy with what they've done on two fronts – the drug donation front, where they're ramping up the capacity and helping with the logistics, to get this stuff delivered, and the second is on the diagnostic and drug front to look at where we still have gaps.

"The best news story we have here is that we have a new diagnostic for sleeping sickness and we have a drug that, although it's in a phase 2 [trial], looks pretty promising as an oral treatment for this."

Sleeping sickness, or African trypanosomiasis, spread by the bite of the tsetse fly, is fatal without treatment. A quarter of those infected are children. Diagnosis at the moment involves a lumbar puncture, and if the patient is fortunate enough to get one, they will need intravenous drugs for days. In some places, there is nothing better than an arsenic-derivative, which kills 5% of those treated. But with the new diagnostic test and possibly a pill, the prospects are transformed. Experts are now for the first time talking about eliminating the disease by 2020, rather than just controlling it.

There is a clear elimination goal for just one of the diseases – guinea worm, which the Carter Foundation has focused on for many years. "We're down I think to 148 cases last year and it's in Mali and there were a few cases in Chad and south Sudan. So we're very close on that. It's turned out with the unrest in Mali and South Sudan they're not going to make the original date for it and so we're having to put more into that," said Gates.

But actual eradication is difficult and not always appropriate. "For most diseases you don't want to try and do eradications, because eradications are very hard and you end up spending a lot on the last small number of cases and only if you really think you can succeed and you are preventing it from coming back, then it becomes very worthwhile, as it is in the case of polio," said Gates, who has put substantial funds and effort into the attempt to rid the world of polio. "So we're pretty careful about when we get people riled up to think true, true eradication."

Better drugs could change the outlook for children infected by roundworm, hookworm and whipworm – the three most common of the soil transmitted helminths – and also for onchocerciasis. Current drugs only kill the juvenile form of the worm.

"It means you have to keep coming back and catching the hatched worms again and again and again for a lot of years. If you can kill the adult worm, that's the human reservoir and it would help a lot," said Gates.

There are now R&D agreements with drug companies to investigate. In the meantime, country programmes have in the last few years been designed to dose children and adults with drugs not for a single disease, but for all those active in their area. That costs 30 cents a person, said Gates – not 30 cents per person, per disease.

More money was announced in Paris, including $50m (£30m) more from the Bill and Melinda Gates Foundation, $50m from the Children's Investment Fund Foundation and $120m from the World Bank.

The World Health Organisation's director-general, Margaret Chan, said: "The tremendous progress we have seen over the past two years is proof of the power of partnerships and the generosity of companies that made commitments under the London Declaration.

"Together with the governments of endemic countries, we are fast approaching the goal of controlling or eliminating many of these ancient causes of human misery. This is a pro-poor initiative that is improving the lives of more than a billion people."

However, Julien Potet, neglected diseases adviser of the Médecins Sans Frontières access campaign, said that while they were glad the campaign was attracting attention to some neglected diseases, others were still forgotten – such as yaws, which can lead to disfigurement and disability, yet can be cured with a single dose of the antibiotic azithromycin.

WHO had struggled to get donations from a major drug company. Potet said: "Another example is snake bite, which is listed as very neglected by WHO. [The drug company] Sanofi has done a good job of donations for sleeping sickness but have told us they were looking at stopping production of anti-venom for Africa."

Donations, in MSF's view, are not always the best way forward, he added, particularly as small drug companies cannot always afford to make them.