“Travellers may be more likely to get an infection because they might be more naive than the local population.”
By In-Kyu Yoon, Dengue Vaccine Initiative director
The travel warning in red, or the highest warning indicating transmission, includes several Pacific island states and territories – American Samoa, Fiji, Samoa, Solomon Islands, Tonga and Vanuatu, and over two dozen countries in Latin American including Brazil and Mexico.
But just how widespread Zika is in the Asia-Pacific is unknown although over the past few years, the virus has been detected in travellers visiting Indonesia and Thailand.
“There is a risk that Zika will become endemic in the Asia-Pacific region, meaning that the infection is maintained in the population without the need for external inputs,” Susann Roth, a medical doctor and senior social development specialist at ADB, tells SciDev.Net.
“The Zika virus is not new to the region. Because we have not invested enough in health data sharing, outbreak investigation, diagnostics and R&D, we don’t yet fully understand Zika and its risks,” notes Roth.
Zika is a flavi virus, which makes it part of the same family as dengue, yellow fever and West Nile. Symptoms include fever, headaches and rashes, which are similar indicators to dengue and may have possibly led some medical experts to mistake Zika for dengue, which is common in the region.
In-Kyu Yoon, director of the Dengue Vaccine Initiative, a consortium which includes the International Vaccine Institute and the WHO, says it is notable that of the handful of Zika cases detected in the Asia-Pacific, many have been from travellers.
“Travellers may be more likely to get an infection because they might be more naive than the local population. But if you have several of them that go into a country and contract this disease and get diagnosed when they go back to their home country, then it’s probably not a totally rare disease,” Yoon tells SciDev.Net.
The WHO has declared Zika a global health emergency. The US-based Centers for Disease Control and Prevention have also urged pregnant women or those planning to get pregnant to consider avoiding countries with known Zika outbreaks or consult doctors before going there.
The disease, which can also be spread through sexual intercourse, has been tied to microcephaly, a rare disorder in which newborns have an unusually small head and brain, and also to Guillain-Barré syndrome, an autoimmune disorder that can cause paralysis.
Incubation period for Zika is roughly a few days up to a couple of weeks. But an estimated 80 per cent of people infected with the virus are asymptomatic, according to the CDC.
Zika was first discovered in 1947 in a monkey in the Zika forest in Uganda that gave the disease its name. But the world’s first real Zika outbreak was in 2007 on Yap Island in the Western Pacific state of Micronesia.
Six years later and 5,000 miles southeast of Yap, tens of thousands of people sought medical care for the illness in French Polynesia. That was the first time it was suggested that Zika is somehow connected to Guillain-Barré syndrome since during the outbreak, the number of Guillain-Barré cases was higher than normal. At this point there was no mention of birth defects, although a retrospective change is possible.
This piece was produced by SciDev.Net’s South-East Asia & Pacific desk.