Scientists in Ghana have found a new way to eliminate elephantiasis, which causes severe swelling, particularly in male genitals, and life-destroying deformities.
Although little-known, elephantiasis — as seen in the 1980 David Lynch film Elephant Man — is one of the most common causes of disability worldwide.
But now scientists at the Noguchi Memorial Institute for Medical Research at the University of Ghana say that DNA barcoding can identify the particular species of blood-sucking Anopheles mosquito that transmits the tiny parasitic worm responsible for the disease when it bites humans.
DNA barcoding is a technique that uses a DNA sequence from a particular region of a genome to capture a species’ unique identity, rather like a teller swiping her laser scanner over your food at the checkout queue.
It’s particularly important for this mosquito, according to John Gyapong, the coordinator of the Lymphatic Filariasis Support Centre (LFSC), because until now scientists have battled to tell the culprit mosquito from its virtually identical cousins, who do not carry the parasite.
The microscopic, thread-like parasitic worms clog human lymph nodes in the adult stage of their life cycles and can cause the swelling, also known as lymphatic filariasis, even at low levels.
The study’s principal investigator, Daniel Boakye, said such barcoding — which needs to be done only on a short sequence of DNA — “makes it easier to target the specific carrier mosquitoes”.
Nonetheless, Boakye warned that “if we are to eliminate the disease” public health workers would have to break the cycle by wiping out the carrier mosquito before it bites humans as well as carry out mass drug administration on infected people.
The research team traversed all of Ghana during both dry and wet seasons for two years, collecting many different types of mosquitoes, checking if they were infected with the parasite and sequencing their genes after the teams returned to the lab.
A member of the Ghana research team, scientific adviser Michael Wilson, said the DNA barcoding was ”a significant breakthrough”.
“We will be able to identify species of mosquitoes that are more dangerous. Apart from killing them directly we will also modify the environment and get rid of breeding habitats, putting up barriers between humans and mosquitoes using treated nets as curtains to screen windows, doors and cover the eaves of homes,” he said.
Wilson said that as yet unpublished research shows that a variety of environmental factors such as temperature influence the range of the parasite-infected mosquitoes and will be able to help scientists predict outbreaks as climate change makes an impact.
The discoveries come after the Global Alliance to Eliminate Lymphatic Filiariasis met last month in Tanzania to coordinate efforts to eradicate the disease, saying that it had affected about one billion people worldwide. — www.SciDev.Net
Fred Baffour Opoku attended the South African Science Journalists’ Association workshop on climate change earlier this year, and has been selected as one of six reporters to go to the climate change negotiations in Denmark at the end of 2009