A neurological condition associated with the Zika virus has been declared a “public health emergency of international concern” by the World Health Organisation’s (WHO) director general, Margaret Chan. Researchers appear certain that the virus is responsible for a massive increase in occurrences of microcephaly, despite a lack of clear evidence to prove causality. Microcephaly – a congenital condition, characterised by abnormally small head size and incomplete brain development, has increased from around five to 200 cases per 100,000 live births in affected areas. There have been roughly 4,000 reported cases in the past three months from Brazil alone.
Unlike Ebola, the virus itself causes only a mild and rarely life-threatening illness – but has been placed in the same category of concern by WHO. Adult infection with the virus is seldom serious: “Zika alone would never be a public health emergency of international concern”, said Professor David Heymann, chair of the emergency committee.
“While many lessons from Ebola apply to Zika, it is essential to remember that these are different diseases and must be treated as such”
Symptoms include fever, rash, and joint pain – though it has been linked to a few cases of Guillain-Barré syndrome (a rare condition which causes paralysis). Concern arises when pregnant women become infected; the virus is thought to have serious consequences for the neurological health and wellbeing of the foetus. In actuality, up to 80 per cent of people infected may suffer only minor symptoms or be entirely asymptomatic, according to Marcelo Castro, the Health Minister for Brazil. This presents a significant problem for gathering data on the disease, and determining a de facto connection with microcephaly (which has been the driving force behind WHO intervention).
“To figure out the link with Zika virus, large numbers of cases of microcephaly have to be traced and assessed and the exposure of the mother to Zika virus has to be established”, said Heymann, going on to add: “It is a very complicated issue”.
With the first confirmed case in Europe of an infected pregnant woman comes further affirmation that prevention is an issue for international concern. No vaccine for Zika currently exists; instead, current interventions must target the Aedes mosquito, which is largely responsible for spreading the virus.
“As long as [the mosquitoes] are reproducing, we are all losing the battle. We have to mobilise to win it”, were the fighting words of Brazil’s president, Dilma Rousseff. She has recently signed a law which allows health officials access to any building suspected of being a mosquito breeding ground – regardless of whether or not the owner can be contacted. Although the WHO is currently developing a diagnostic test for all three of the viruses caused by the Aedes mosquito (Zika, Dengue, and Chikungunya), which should be viable within the next month, a vaccine is much further away. Jacques Wagner, the Brazilian president’s chief of staff has told reporters: “It could be between three and five years”.
Until then, resources must be directed at management of the mosquito population and, perhaps most importantly, aid for those affected by the spike in incidence of microcephaly – whether Zika is responsible or not.