World Health Organisation (WHO) officials convened on 1 February 2016 to discuss strategies to combat Zika – a virus that is set to “spread explosively across the Americas”, says Margaret Chan, Director-General of WHO. Brazil estimates that they have 1 million infections in their country alone, and the WHO epidemic response team estimates that this number may rise to 3-4 million in the next year. In comparison, ebola infected 23,200 people and killed 9,300. It’s no wonder that the WHO declared Zika a public health emergency after the special session.
Zika came to the world stage last October when 3893 babies were born with microcephaly – abnormally small brains with enormous consequences for their health. The jump from fewer than 200 a year before 2015 could not be explained by other risk factors for microcephaly – drugs, alcohol rubella infection or exposure to specific toxic chemicals. Although scientists can’t create a causal relationship from observational data, Chan added that the link has “rapidly changed the risk profile of Zika from a mild threat to one of alarming proportions”.
Brazilian researchers are already trying to prove the causal link between Zika and microcephaly in humans, although this will take nine months. As the virus spreads to El Salvador, researchers have also begun to investigate its effects on neural and immune systems, focusing on Gullian-Barre syndrome, a condition that causes temporary paralysis. The related dengue virus is spread by the same Aedes aegypti but there are no specific dengue medications or vaccinations, even though the disease has been on the public health radar for much longer. Until a vaccine is found, President Dilma Roussef is committed to mosquito eradication instead.
Inspectors spray the area around the Sambadrome in preparation for Brazil’s famous Carnival in early February – a result of Brazil’s declared national public health emergency. The move has allowed Brazil to mobilise 220,000 troops to assist 310,000 in the drive to eradicate the Aedes mosquito. Regular fumigation, house visits to ensure people remove stagnant water, and campaigns to increase awareness were effective at rendering Brazil free of Aedes in 1958. Indeed, I come from Singapore, a tropical city smack in the centre of South East Asia that would otherwise be a hotbed of yellow fever, dengue and malaria. Similar campaigns have been effective at keeping infection rates low, and the question remains whether mosquito eradication can be carried out on a wider regional, or even global scale to prevent it from emerging again.
Promising new technologies have the potential in the mosquito eradication drive. Successful tests in the Cayman Islands and Brazil have shown that the introduction of hybrid male mosquitoes can cause local populations to crash. These mosquitos have been modified so that they are fitter than ordinary male mosquitos, but their offspring are sterile. Within one generation, the population of mosquitos can be wiped out. The experiments had only been carried out on the scale of a few neighbourhoods and it remains to be seen if funding and logistical support can be created to expand its reach. It might not be possible to spread these creatures across all of Brazil, but in rural areas or rainforest where there are plenty of unattended sources of stagnant water that cannot be emptied or fumigated easily, it could prove invaluable.
Zika could have widespread, global impacts. Athletes are worrying what lies ahead for the 2016 Olympics in Rio, even as IOC officials assure the public that they are taking all necessary precautions – including checking sites around the Olympic stadiums. Canadian health services are already rejecting blood donations from travellers who have been to Zika-infected countries. Airlines are already offering refunds to travellers who have booked tickets to Latin America. Indeed, Zika has also begun increasing the shares of biotechs researching infectious diseases like Inovio Pharmaceutical and Intrexo by 11% and 11.2% respectively. Pest control company Rollins has seen increases of 1.1% after their CEO Gary Rollins mentioned Zika in a conference call.
Some would even venture that Zika would lead to Latin American countries relaxing abortion bans. Most Latin American countries only allow abortion in cases of rape, or severe brain defects. El Salvador, one of the most affected by Zika, have some of the worst legislation imprisoning medical officials and women up to 40 years for attempting abortion. The laws are so strict that women with still-born infants or miscarriages are reported and sentenced. Governments in Latin America have responded by telling women to avoid getting pregnant – El Salvador leading with a two year health advisory against pregnancy. An element of racial profiling has begun to creep in as Panama directly advises indigenous women in communities with high infection rates to avoid getting pregnant. Even though prevention through hormonal methods and condoms is far cheaper than alternatives, it remains unlikely that Zika would reverse the conservative momentum that has been built up behind such laws. With any luck, a more specific provision might be created for pregnant women whose ultrasounds reveal microcephaly.
WHO is still reeling from criticisms that their reaction to ebola was too little, too late. More than 3,100 cases of pregnant women with Zika have been found. Zika virus is diagnosed through virus isolation from blood samples. Diagnosis by serology can be difficult and can take up to two weeks to confirm, as the virus can cross-react with dengue, West Nile and yellow fever. Even in the crisis, there is opportunity. If Zika can create the political momentum to take a serious toll on mosquito populations globally, we have a chance of eliminating an entire disease vector. We even have a chance of expanding access to birth control and abortion for an entire continent of women. The call for strong leadership is louder than ever.