Zika marches on: lessons not learnt

It is only six months since the WHO declared Zika to be a global health emergency and since then the disease has continued its unrelenting march across the world now affecting more than 65 countries and creating unease, fear and panic particularly among pregnant women and their families.

Up until 2013 Zika was regarded as a largely benign and harmless infection with mild symptoms. All that has now changed and since the WHO's announcement Brazil has suffered tens of thousands of cases and a huge surge in the number of babies born with microcephaly. In addition, at least 14 countries have now reported cases of microcephaly and other central nervous system disorders and 15 countries have reported an increased incidence of Guillain-Barre syndrome.

Despite all this some are now saying that the epidemic has peaked in Brazil and Latin America but in reality it may take years for it to fully disappear and its effects will linger much longer.

In the meantime work goes on to produce a vaccine. History suggests that a fully effective vaccine that is widely available will most probably appear when the epidemic has run its course and we are confronted by another "new" infectious disease threat.

Do the lessons we have learnt from Zika, Ebola Swine Flu and SARS count for anything and do they offer us an insight into how to contain and stop future epidemics?

The battle to contain and eliminate such epidemics still rages and it is a battle that we are not winning. In the case of Zika we know that it is spread by the aedes mosquito but we are really unable to do much about limiting the distribution of the mosquito. Confronted as we are by a mosquito which over the last two centuries has beautifully adapted to living with and around humans our chances of winning the battle are remote.

The failure of the widespread spraying campaign involving more than 200,000 soldiers in Brazil suggests as much.

Ebola and now Zika demonstrate how much we have to learn and how we can be caught off guard and hindered by the poor surveillance and response mechanisms at our disposal.

The first battle against Ebola has been won but the war continues and the disease has simply retreated back into the security of its natural animal reservoir. How long before it ventures out again to attack humans is anybody's guess and we should not delude ourselves that the war has been won as a large part of West Africa still remains vulnerable to future outbreaks.

In particular, parts of Africa and Asia suffer from weak government institutions, poor health services, environmental degradation, poverty, human migration and conflict and political instability.

All this creates the perfect storm conditions for an outbreak of infectious disease particularly where such things result in the disturbance of natural reservoirs of disease where infections have been nurtured for centuries.

But at the moment world attention is focussed on Zika. Today, probably two million Brazilians have Zika and now cases are appearing in the USA and Western Europe. In Puerto Rico at least 5,500 people have tested positive for the disease including approximately 670 pregnant women. The disease is also prevalent in American Samoa and the US Virgin islands.