Eisai has become the first Japanese pharmaceutical company to link up with the World Health Organisation on neglected tropical diseases, signing a deal to supply drugs for lymphatic filariasis.

Eisai has recently agreed to produce and supply to WHO free of charge up to 2.2 billion 100mg tablets of diethylcarbamazine (known as DEC) over a six-year period between 2012 and 2017. The treatments will be produced at the Tokyo-headquartered firm's facility in Visakhapatnam (Vizag), Andhra Pradesh in south India. The total number of tablets is enough to treat 300 million people with LF.

Eisai chief executive Haruo Naito worked closely with WHO as president of International Federation of Pharmaceutical Manufacturers & Associations, a post he held until earlier this month. Doctors at WHO were looking for the support of a Japanese drugmaker to help eliminate LF, and approached Eisai, which met with officials of the agency in August and September.

LF is a parasitic disease that is transmitted to humans by the bite of a mosquito. Once transmitted, it can lead to serious physical disabilities such as elephantiasis, and although eradicated in Japan in the late 1970s, it still affects an estimated 120 million people in 81 countries, notably in Africa and south-east Asia.

Two of the three medicines used to treat LF are currently donated by GlaxoSmithKline (albendazole) and Merck & Co (ivermectin). However, there is a global insufficient supply of the third treatment, DEC, and Margaret Chan, director-general of WHO, said that Eisai's contribution "will eventually close the gap in drug availability, particularly for poor countries where most cases of this disease occur".

As well as LF, Eisai is supporting the development of a therapy for the treatment of Chagas disease through a partnership with the DNDi (Drugs for Neglected Disease initiative). A compound for this project is currently in Phase II trials in Latin America.

_In addition, the company says it has a promising candidate for the treatment of malarial encephalitis, which is currently being evaluated in preclinical studies.