THE Philippines is among the top five countries at greatest risk of spread of the dreaded Zika virus, a study conducted by Canadian and British researchers and published in the medical journal Lancet Infectious Diseases concluded.
The study, which was carried out by scientists from the London School of Hygiene and Tropical Medicine, Oxford University, and the University of Toronto, first identified the ‘ecological niche’ in the Americas where conditions were most suitable for Zika virus development and transmission, and then modeled travel patterns from that area—which covers a large part of South, Central, and North America—to Africa or the Asia-Pacific region for the year from December 2014 through November 2015.
The data gathering for the study involved recording airline ticket sales for departures from all 689 cities with one or more airports in the region of origin, the researchers explained. The study then matched the travel data to data on the appearance of Zika infection in terms of the time interval before new cases began to appear, the number of new cases, and the rate of infection, and then examined the general characteristics of those countries where Zika spread most quickly.
The study confirmed that the countries most vulnerable to Zika had similar risk factors, including high travel volumes from Zika-affected areas in the Americas; local presence of mosquitoes capable of transmitting Zika virus under suitable climatic conditions; large populations; and limited health resources.
The countries the study determined have the greatest risk based on these criteria include India, China, Indonesia, the Philippines and Thailand. Other countries with an elevated risk of Zika infection include Nigeria, Pakistan, Vietnam and Bangladesh.
The study noted that the risk of the spread of Zika could actually be much greater than its results indicated because other species of the Aedes mosquito could be effective vectors for the virus. The Aedes aegypti mosquito, which also can carry the dengue, malaria, Chikungunya, and yellow fever viruses, is well-known as a carrier of the Zika virus, as is this Aedes albopictus mosquito, although in the latter case, the study said, the efficiency of the mosquito’s ability to transmit the virus is still being researched. Two other Aedes species, A. africanus and A. Hensilli, may also be carriers of the Zika virus.
The Aedes aegypti and Aedes albopictus mosquitoes are both common in the Philippines, and the Aedes Hensilli mosquito, which originated in the Caroline Islands, is also suspected to be present here.
“The potential for epidemics to occur in parts of Africa and the Asia Pacific region is particularly concerning, given that the vast numbers of people who could be exposed to Zika virus are living in environments where health and human resources to prevent, detect and respond to epidemics are limited,” said study author Dr. Kamran Khan of St. Michael’s Hospital, Canada.
Last Tuesday, the Department of Health announced that two more cases of Zika infection had been confirmed in the Philippines, bringing the total number of cases to eight so far this year. Health officials are concerned that the number may increase, particularly because of an ongoing outbreak in Singapore, where nearly 350 cases have been recorded in the past three weeks.