ON February 1, Margaret Chan, director general of the World Health Organization (WHO), called Zika virus infection an “extraordinary event” that needed a coordinated response.

The WHO alert puts Zika in the same category of concern as Ebola. Does this mean that Zika is as deadly as Ebola? Not so. The WHO declaration means research and aid will be expedited and coordinated to tackle the infection and the public health conditions which facilitate spread of the disease.

In Jamaica, it is important that we work across the political divide to minimise the impact of a disease which has arrived on our shores. Any attempt to score political points at the expense of our public health should be swatted down with the same ferocity with which we swat the mosquito.

WHY ALL THE HYPE?

Zika virus is not a new virus. It is transmitted by the Aedes aegypti mosquito. Zika virus was first identified in Uganda in 1947 in rhesus monkeys and subsequently in humans in 1952 in Uganda and the United Republic of Tanzania. The time from exposure to symptoms is likely a few days. Only one in five people infected with Zika virus becomes ill.

The symptoms are usually mild and include fever, skin rashes, conjunctivitis (red eye), muscle and joint pain, malaise (”low feeling”), and headache. The symptoms are similar to many other viral illnesses including dengue. Typically, the symptoms last two to seven days.

Fear has occurred because of temporal and spatial associations of Zika virus outbreaks in French Polynesia and Brazil in 2013 and 2015, respectively, with neurological and autoimmune complications. The specific complications include: babies born with microcephaly and development of Guillain-Barre syndrome (GBS) — a potentially paralysing illness.

It has not been conclusively proven that Zika causes these illnesses; however, the dramatic surge of these relatively rare illnesses in areas most heavily affected by Zika illness, and at the time of outbreak, suggests at worst more than a casual association. New evidence emerging suggests the cases of microcephaly may be region specific.

WHAT DOES THE RADIOLOGIST SEE?

1. Microcephaly

Microcephaly is a birth defect where a baby’s head is smaller than expected when compared to babies of the same sex and age.

In foetal imaging, it is usually defined as foetal head measurements (for example, head circumference) falling below two standard deviations expected for gestational age or falling under the third percentile. Other authors use three standard deviations, which narrows the diagnosis to less than one per cent of the population. Microcephaly is usually associated with microencephaly (small brain).

Babies with microcephaly can have a range of problems, depending on the severity of the condition. Some of the associated conditions include:

• Seizures;

• Delayed achievement of developmental milestones;

• Learning disabilities;

• Problems with movement and balance;

• Feeding problems;

• Hearing loss; and

• Vision problems.

These problems can be mild to severe, and a baby with microcephaly will often need lifelong care. The established causes of microcephaly include the following:

• Genetic causes, for example Trisomy 13;

• Certain infections, for example, rubella, toxoplasmosis and Cytomegalovirus;

• Severe malnutrition; and

• Exposure to harmful substances, such as alcohol, certain drugs or toxic chemicals.

The radiologist is able to make the diagnosis of microcephaly during pregnancy by ultrasound. The specific test is called an anomaly scan. Many disorders of brain development will also be seen at this time.

The head circumference measured is compared with the measurements of other foetal body parts to see if growth of the head is retarded. Other radiological investigations such as MRI and to a lesser extent CT scan may also be used to assess brain development before and after birth.

2. Guillain-Barre syndrome

Guillain-Barre syndrome (GBS) is a rare disorder in which a person’s immune system damages their nerve cells, causing muscle weakness and sometimes paralysis. Symptoms usually last for a few weeks. Most people recover fully from GBS, but some people have long-term nerve damage. In rare cases, people have died from GBS, usually from difficulty breathing.

Infection with the bacterium campylobacter jejuni is one of the most common risk factors for GBS. People may also develop GBS after having the flu or other infections, for example, cytomegalovirus and Epstein-Barr virus. Rarely, does GBS develop within days or weeks after getting a vaccination.

GBS is diagnosed by a combination of clinical presentation, CSF (fluid from the spine) study and electrophysiological criteria. Radiological studies are ordered to exclude other causes of muscle weakness or paralysis, and in cases where nerve conduction studies and CSF examination are not specific. MRI of the spine is useful for excluding other aetiologies, such as transverse myelitis and spinal cord compression. Contrast enhanced MRI of the spine may reveal enhancement of the conus medullaris (tip of the spine) and of the nerve roots which form the cauda equina.

GBS is managed with IV immunoglobulins or plasmapharesis along with supportive measures. Typical improvement occurs after a number of weeks to months.

TAKEAWAY MESSAGE

It is the lack of understanding about the pathogenesis of Zika that drives fear. While it is common knowledge that the disease is spread by the bite of an infected mosquito, there is emerging evidence that the disease may also be sexually transmitted. In fact, a case of sexual transmission has been reported in Texas.

There is no vaccine currently available to prevent Zika virus; therefore, prevention is the mainstay of management. To this end, co-operation between all the relevant government and non-government organisations to educate the public is essential.

Essential prevention steps include, but are not limited to the following:

• Spraying of insecticides to control the mosquito population;

• Environmental clean-up to remove mosquito-breeding sites;

• Wearing long-sleeved shirts and long pants;

• Staying in places that use door and window screens;

• Using mosquito screens;

• Using approved age-appropriate insect repellants. Remember not to use insect repellants on children younger than two months of age;

• Using permethrin-treated products; and

• Instituting appropriate protocols for blood donation.

SPECIAL CONSIDERATION MUST BE MADE FOR PREGNANT WOMEN

• Every effort should be made to delay pregnancy in areas with Zika virus outbreaks.

• Pregnant women in any trimester should avoid travel to areas in which Zika virus transmission is ongoing. If travelling cannot be avoided, then every effort should be made to avoid mosquito bites.

• Remember that insect repellants are safe and effective in pregnant or nursing mothers.

Stay calm, educate yourselves, use common sense methods of protection, and clean up your environment.

Dr Duane Chambers is a consultant radiologist and founding partner of Imaging and Intervention Associates located at shops 58 and 59 Kingston Mall, 8 Ocean Boulevard. He may be contacted through the office numbers 618-4346 or 967-7748.