COMMENT As we face the threat of the Zika virus, we must recognise that we are on a ‘learning curve’ or a ‘state of evolution’ as to our understanding of this problem. What we know today may change dramatically as doctors and scientists understand this condition better.

Unfortunately, some individuals circulate or voice opinions that are not founded on data or evidence and can confuse us. As such, it is important to keep abreast of good information (evidence based) as it becomes available.

Time and good data will make uncertainties clearer and enable us to respond to this challenge more meaningfully.

This article is to offer answers (where possible) to some common frequently asked questions (FAQs) and also express some of our uncertainties. I will try and provide references to answers offered so that individuals can read the data for themselves.

Is Zika transmission happening in Malaysia?

We know that Zika was first identified in Uganda in 1947 and it then spread to Asia. It was detected in an Aedes mosquito in Peninsular Malaysia in 1969. In September 2014 a tourist was found to be infected with Zika after travelling in Sabah.

So Zika has been around, possibly circulating in low numbers for some time. In the past two weeks, we have seen one Malaysian visitor to Singapore get infected and another with local transmission in Sabah. Despite testing many mosquitoes and patients with the symptoms, the Ministry of Health has yet to identify more cases or the spread of the virus.

Will Zika spread in Malaysia?

We expect it will. Although the virus has been around for some time, most Malaysians are not immune to it, hence it can spread easily. In addition, we have the appropriate mosquito vectors in abundance, the Aedes mosquitoes.

Remember that it is a mild illness with some fever, rashes, red-eyes and joint pain. The majority are asymptomatic, i.e. may be infected but not show signs. These asymptomatic and mild cases still have the virus in the body for a few days and it can spread to others if they are bitten by Aedes mosquitoes or via sex for longer periods or to their foetus.

Why do some countries seem to have a worse outcome or larger epidemic?

We are uncertain about this but definitely testing for cases increases the numbers we will detect. One scientific opinion, from Imperial College London, based on two preliminary studies, suggests that a previous dengue infection may amplify Zika infection.

This may account for the rapid spread in South American countries like Brazil, as well as in Singapore (and possibly us in the near future).

Does Zika cause brain damage (microcephaly) in unborn babies?

Zika on its own is not very worrying. What has focused our attention on is the brain damage (microcephaly) in unborn babies that has been linked to it in some countries, especially Brazil.

But some have argued that Zika is not the cause of the damage but environmental toxins and pesticides are. They argue that the rates of microcephaly are low in some countries and that there is a ‘cover-up’.

The World Health Organisation (WHO) and others have tried to evaluate all rumours and offer an evidence-based response.

But perhaps the best evaluation of the risk is a good publication in the New England Journal of Medicine that looked at all the evidence and concluded that “a causal relationship exists between prenatal Zika virus infection and microcephaly and other serious brain anomalies”.

An important piece of evidence is that, in a number of documented Zika infections in pregnancy, where the babies have died (in the womb or after birth), the brain tissue has documented Zika virus. In addition, babies born with brain damage related to Zika have been found in a number of countries including the USA.

Another important observation is that in a small number of twins, where the mother was infected with Zika, only one developed microcephaly. This refutes the possibility of an environmental toxin as both babies would be damaged in the womb.

As some of these twins were dizygotic (meaning that they develop from two different eggs) it suggests that genetic factors are possibly important in whether an unborn baby develops brain damage.

The general public must realise that there are many causes for microcephaly in newborn babies, including genetic/chromosomal defects, other congenital infections (e.g. rubella, toxoplasmosis, cytomegalovirus), toxins (alcohol, some drugs or toxic chemicals), blood supply interruption to the brain in the womb, etc. So infection with Zika in pregnancy may not always be the cause of the damage seen.

Is there more than one type of Zika virus?

There are two Zika strains (or lineages), an African strain and an Asian strain. The strains currently circulating in the Western Hemisphere (and in Singapore) are more closely related to the Asian lineage than to the African lineage. We are uncertain if there is a difference in the behaviour of the strains in affecting the unborn child.

Should I have an abortion if I am pregnant and infected with Zika?

It is important to realise that the reason babies have a small head (microcephaly) with Zika infection is because the brain has become damaged and is not growing so well, i.e. a smaller brain with damage to brain cells. The degree of damage is only now being described and is variable.

From experience with other congenital viral infections, the more severe ones may die early. Some will live with severe disabilities, others with relatively mild developmental problems.

Abortion is not strictly illegal in Malaysia. An exception clause has been added to Section 312 of the Penal Code, which states: “A medical practitioner registered under the Medical Act 1971 who terminates the pregnancy of a woman… if such medical practitioner is of the opinion, formed in good faith, that the continuance of the pregnancy would involve risk to the life of the pregnant woman, or injury to the mental or physical health of the pregnant woman, greater than if the pregnancy were terminated.”

Note that the clause includes the mental health of the mother as well. The Health Ministry has clear guidelines when a termination of pregnancy can be done.

The decision to have an abortion must be a careful one and should follow the ministry's guidelines. It requires first to have a confirmed diagnosis of Zika in pregnancy. Testing can be done in a number of government hospitals and private laboratories (see the chart below).

Secondly an obstetrician experienced in detailed foetal ultrasound should evaluate if the unborn child has brain damage. Finally, the parents should make an informed decision with their doctor in view of the available information. It is important to note that terminations of pregnancy after 22 weeks of gestation (about months pregnant) are difficult.

The Royal College of Obstetricians and Gynaecologists in the UK has stated: “When a significant brain abnormality or microcephaly is confirmed, the option of termination of pregnancy should be discussed with the woman, regardless of gestation.”

What about sexual transmission of Zika?

Zika is an unusual Flavivirus in that it can spread by means other than mosquitoes. It is now recognised that the virus is transmitted sexually and can remain in the semen for up to six months and the vagina for some time (maximal duration uncertain).

This means that Zika can spread not just by mosquitoes but also by sexual contact and blood transfusions. Remember that 80 percent of people infected with Zika may not be aware they are infected. Of more concern is a recent study on mice where the virus replicated in the vagina and damaged foetal mice brains.

This is early research but it may suggest that sexual infections may be potentially more harmful to the foetus.

Can we control Zika in Malaysia if it spreads?

A tough question and most countries doubt they can. But there has been remarkable success in Cuba with army deployment to support public health efforts.

But there is concern with the impact of such a volume of insecticide use. Reports from Florida show concern with the death of other insects, especially millions of bees.

One recent study showed that some female Aedes aegypti mosquitoes can pass the Zika virus to their eggs/offspring. This highlights the importance of not just killing the adult mosquitoes but also the eggs.

However, we can definitely reduce the intensity of any Zika epidemic if the general public makes a serious effort to reduce Aedes breeding sites. The impact on dengue would also be significant.

Will a vaccine save us?

Vaccinating against Zika is an important strategy and one early clinical trial testing the first vaccine against Zika has just started. Some are advocating for a dengue and Zika virus combination vaccine, in view of concerns. However vaccine development takes time and lots of research and it is unlikely we will see a viable product in the next two to three years.

When will we see the impact of a Zika virus epidemic?

Assuming that Zika damages a certain percentage of unborn children, then the full impact of the Zika virus epidemic will be seen one to two years later (and beyond), when larger numbers of microcephalic babies are born. That is when families and the health services will face the challenges of supporting all these disabled children.

Note also that there is some preliminary data from experiments infecting adult mice brains with Zika that showed damage to some brain cells. What this means for the developing brains of young children is still uncertain.

I hope this discussion has been useful to summarise some of the concerns and current evidence. There are more questions than answers at this stage. The public should be proactive to read good data as it comes out so as to make informed decisions for their health.

DR AMAR-SINGH HSS is Senior Consultant Paediatrician (Community) and Head, Paediatric Department, Hospital Raja Permaisuri Bainun, Ipoh.