Relationship Between Microcephaly and the Zika Virus.

by

Ngouagna Edwin Longchi 

Medical Laboratory Science, 

Scientific Journal Club

Faculty of Health Sciences

University of Bamenda, Cameroon.

edwinlongchingouagna@gmail.com

Content

•Introduction.

•Microcephaly and related causes.

•Zika virus and associated diseases.

•Case study of Brazil, is there a link between microcephaly and the zika virus? , what piece of work is currently going to prove the relationship?, can a vaccine be developed?

•Prevention.

•Conclusion.

Introduction.

What is microcephaly?

Microcephaly is a medical condition in which the brain does not develop properly resulting in a small than normal head. It can be present at birth or develop in the few years after birth. Infants with microcephaly are born either with a reduced or normal head size. Subsequently, the head fails to grow, while the face continue to grow at normal rate producing a child with a small head, a receding forehead, a loose, often wrinkled scalp.

Fig 1: microcephaly (left), normocephaly (right).

People with microcephaly were described as “pin heads”, “monkey man”, and “little boy”.

Causes of microcephaly.

Microcephaly is congenital and acquired.

Congenital microcephaly is caused by gene deletion, single gene defect, autosomal recessive disorder, chromosomal abnormality, or toxin induction during the period of cell migration.

Acquired microcephaly is caused by disruptive injury e.g. ischemic stroke, vertically transmitted infection e.g. toxoplasmosis, others are trauma, metabolic disorders, drugs.

Infants with microcephaly have delay motor functions and speech, hyperactivity, intellectual disability, convulsions may also occur, clumsiness and spastic quadriplegia (paralysis of both arms and legs).

Microcephaly has no cure.

What is the zika virus?

The zika virus is a non-living microorganism that is capable of replicating only inside a host, member of the family flaviviridae, and genus flavivirus and grouped under group iv positive single stranded RNA. Isolated from the zika forest Uganda in 1947. Transmitted by the mosquitoes Aedes aegypti, Aedes albopictus, sexual intercourse, vertical transmission (mother to child).

This virus causes a wide range of infections cutting across dengue, yellow fever, Japanese encephalitis, and microcephaly though a thought as this piece of work is to find out.

Now, we ask the mighty question, is there a relationship between the zika virus and microcephaly?

              In 2015, zika virus RNA was detected in the amniotic fluid of women whose fetuses had microcephaly indicating that the virus had crossed the placenta and could have caused mother-to-child infection.

           In our case study, we look at Brazil and Rio de Janeiro in February 2016 where in Brazil brain tissues from two new borns with microcephaly who died within twenty hours of birth, placenta, and other tissues of two miscarriages (eleven and thirteen weeks) tested positive for zika virus using reverse transcriptase polymerase chain reaction(RT-PCR). In a cohort study of pregnant women in Rio de Janeiro, zika virus infection was associated with fetal death, placental insufficiency, fetal growth restriction, and central nervous system injury (microcephaly and ventricular calcifications) in twelfth out of forty-two studies using ultra sound.

         According to WHO on the 5^th of February 2016, a causal link between the zika virus and microcephaly was strongly suspected but not yet scientifically proven although the microcephaly cases in Brazil are spatio-temporarily associated with the zika outbreak in Brazil as reported by the BBC in early march 2016, more careful investigation and research work need to be done to better understand the relationship.

       While waiting for the research work, can a vaccine against the zika virus be produced?

Vaccines exist for many flaviviruses such vaccines for yellow fever virus, Japanese encephalitis but none for the zika virus. However, report shows that in early march 2016, eighteen companies and institutions internationally are working on a vaccine against the zika meanwhile the WHO experts suggested that the priority should be to develop inactivated and other non-live  vaccines that have a safety profile suitable in pregnant women and those of child bearing age. Nikos Vasilakis of the center of biodefense emerging infectious diseases predicted that it may take two years to develop a vaccine, but 10 to 12 years may be needed before regulators for public use approve an effective zika virus vaccine.

How do you and I prevent the zika virus?

           As of February 2016, the CDC recommends that men who reside in or have travelled to an area of active zika virus transmission such as equatorial Africa, south east Asia who have a pregnant partner should abstain from sexual activity or to correctly use condoms in whatever type of sex for the duration of  pregnancy to avoid infection leading to vertical transmission with possible microcephaly  whereas those with non-pregnant partners may require abstinence or condom use though the CDC did not specify how long these practices should be followed.

          Pregnant women should not travel to zika virus endemic regions, as of January 2016, the CDC and other governments issued travel guidelines and warnings.

          In Colombia, Ecuador and some other countries, women were advised to postpone getting pregnant until more is known about the risk.

Microcephaly has no cure so, how do we manage a microcephalic individual?

 Treat the signs and symptoms to confer relief for example speech therapy could help in delay speech.

Conclusion.

The zika virus could be one of the possible causes of microcephaly however; research is currently going on to affirm this.

References.

Understanding pathophysiology; Huether-McCance Brashers-Rote.

Microcephaly-Wikipedia, the free encyclopedia.

Zika virus-Wikipedia, the free encyclopedia.

BBC report of early march 2016.