A health worker administers medication for lymphatic filariasis. Photo by: Ruth McDowall / RTI International / CC BY-NC-ND

Tonga eliminates filariasis after a 300 years epidemic

The World Health Organisation (WHO) confirmed this week that the kingdom of Tonga eliminated the lymphatic filariasis disease after an epidemic of three centuries that, only 40 years ago, infected 45% of the population, with one in 12 people declaring elephantiasis.

Elephantiasis of the legs due to filariasis. Luzon, Philippines. PD-USGov-HHS-CDC

This lymphatic filariasis plague is caused by a parasitic worm, transmitted by mosquitoes. Some of the ill will develop a syndrome called elephantiasis, causing their limbs or genitals to swell to huge proportions, a handicap for work, relationships and reproduction. Of 120 million people infected with lymphatic filariasis worldwide, 40 million suffer from elephantiasis.

The worst of all: known medications will kill the larvae but not the adult worms, meaning that there are no easy treatments for elephantiasis. Some cases of scrotal elephantiasis can get a surgery, and an antibiotic treatment was discovered in 2014 to be able to kill a symbiotic bacteria living in the adult worms, causing it to become sterile and die after a couple of years… Hopes, but still a real nightmare for the infected.

But this is now history in Tonga. As reported by the NGO media platform Devex,  Tonga was once the most infected country in the world but has now eliminated the disease, meaning that “the incidence rate is less than 1 percent — which is the WHO-mandated benchmark indicating a disease has been eliminated as a public health problem — in all endemic areas in the country. “They may or may not be completely free of the infection by this time,” Corinne Capuano, director of WHO’s Pacific Technical Support Division and country representative in Fiji, told Devex. Tonga needs to remain vigilant and continue post-elimination surveillance for potential emergencies or reintroduction of the disease over the next five to 10 years, she said.

The small Polynesian kingdom benefited from a global push against the illness initiated by the WHO in 2000. Three multinational pharma companies, GlaxoSmithKline, Merck & Co and Eisai Inc., committed to donate huge stocks of the necessary medicines.

In the infected countries, local authorities had to reach up to 65% of the population every round of treatment, during more than 6 consecutive years for the initiative to be successful. Tonga outdid all other countries, as explained by Corinne Capruano to Devex: “They in fact had a reported coverage of over 80 percent in each of the six rounds ranging between 81 percent and 92 percent. That is among the best consistent treatment coverages we ever had anywhere.”

Tonga now rejoins the growing list of countries that eliminated lymphatic filariasis, following neighbors Marshall Islands and Togo who freed themselves of the worms earlier in 2017.


Photo credit: A health worker administers medication for lymphatic filariasis. Ruth McDowall / RTI International / CC BY-NC-ND

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