Tag Archives: Wolbachia

China to Join and Expand Anti-Dengue Project

The dengue virus, transmitted by mosquitoes and threatening over half the world’s population, is described by the WHO as ‘’a leading cause of hospitalization and death among children’’. Symptoms include a high fever, vomiting, swollen glands, rashes or muscle pains; however, the virus ‘’occasionally’’ mutates into severe dengue, adding bleeding gums, severe abdominal pain, and fatigue to the list. The next 24 to 48 hours of this stage may end with the death of the infected: no vaccine or specific treatment has been developed for the dengue virus, which can have a mortality rate of up to roughly 20%.

‘’Before 1970, only nine countries had experienced severe dengue epidemics. The disease is now endemic in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, South-east Asia and the Western Pacific. […] Cases across the Americas, South-east Asia and Western Pacific [, the three most heavily-impacted regions] have exceeded 1.2 million cases in 2008 and over 2.3 million in 2010.’’ (again quoted from the WHO page relating to dengue fever) Almost 100 000 000 new cases are discovered yearly in the tropical regions, with over 40 000 deaths being tied to this disease.


In an innovative push to eradicate this disease, which today has spread to threaten Europe and the United States, four countries—Australia, Brazil, Indonesia, and Vietnam—will be releasing hordes of genetically-modified mosquitoes. With research beginning in the Australian University of Monash in 2008, it was eventually discovered that a bacteria taken from fruit-flies could severely hamper a mosquito’s ability to carry dengue fever.

This intracellular bacteria, dubbed Wolbachia, spreads amongst the mosquito population as they reproduce. If a contaminated male reproduces with a non-infected female, the eggs will be incapable of turning into larvae. However, if it is only the female who is infected, she will transmit the bacteria to the following generation. Wolbachia cannot be transmitted to humans.

Following tests in laboratories mimicking natural settings, Australian researchers released over 300 000 mosquitoes carrying Wolbachia in two northeastern towns. Four months later, 100% of the first town’s mosquito population and 90% of the second’s was infected with the disease. However, two weeks after that survey, rates had dropped to 95% and 81% respectively. Those responsible believe the dry season may have attracted external mosquito populations to the experiment towns.

That experiment equally proved that it is very rare for the virus to spread far beyond the release point: it appears infected mosquitoes were found outside of the towns on only three occasions. This should allay legal concerns, if two neighbouring political entities disagree on whether or not to use the genetically-modified pseudo-vaccine.

Another technique tested in Brazil, involving a transmittable gene devastating mosquito populations, has reduced dengue fever levels by 85% and mosquito populations by up to 90%. Indonesia and Vietnam are also experimenting with mosquito-borne counters to this disease.


Recently, southern China has seen an explosion of dengue fever cases: the number of reported cases in Guangdong ballooned from 6 089 to 8 273 in three days, over 15 times the rates at this time last year. The provincial capital, Guangzhou, hosts 6 986 of those affected by the worst epidemic of recent history.

While China’s record on transparent disease-fighting operations is unimpressive, it is logical that this fairly simple technique would appeal to Beijing. The subtlety is undeniably higher than the hecatombs targeting cattle and the sealing off of the Jiuxian township following an outbreak of foot-and-mouth north of the capital.


It also seems logical that China would attempt to distribute this genetically-modified weapon to various African nations threatened by the dengue fever: this fits with the emphasis on soft power China is giving Africa, most notably by serving as mediators in the South Sudanese civil war (although officially the mediators are continuing ‘’peace promotion work between South Sudan and Sudan’’, not intervening in another nation’s internal affairs) and preparing Benin to tackle a potential spillover of Ebola from neighbouring Nigeria.

Dengue fever is present throughout sub-Saharan Africa, or in regions worldwide between the latitudes of 35-North and 35-South and with an altitude below 1 000 meters. Members of the same genus include the West Nile virus, the yellow fever virus, or the tick-borne encephalitis virus; it is not clear if the techniques currently being employed by Brazil, Vietnam, Indonesia, or Australia are capable of counteracting these viruses as well.