Zika virus suspected to cause joint abnormalities in babies exposed in the womb
Zika infection during pregnancy may result in joint abnormalities in the developing foetus, as well as brain and skull deformities, experts in Brazil fear.
A team of researchers working in the Brazilian city of Recife, close to the epicentre of the outbreak, have published their findings in BMJ Open – and they make for worrying reading.
The team of doctors, led by Dr Vanessa van der Linden – the paediatric neurologist responsible for sounding the alarm last summer when she noticed a sudden and marked increase in unusual microcephaly cases – have been studying a group of newborn babies, suspected to have been exposed to the Zika virus in the womb. They observed seven babies who had deformed hip, knee, ankle, elbow, wrist and finger joints. These deformities, known as crooked joints or the medical term arthrogryposis, are caused by faulty muscles, which may be either too tight or too lax, resulting in the growing joints being supported in unnatural positions, causing them to become malformed.
Dr Linden says scans of the infant’s brains appear to support their suspicion that the Zika virus attacks brain nerve centres which direct the muscles, rather than the actual joints. Most of the babies studied are also said to have the (now characteristic of Zika exposure) under-developed and misshapen head, in addition to the joint problems. Since the findings were collated, says Dr Linden, a further 14 babies have presented with similar joint deformities.
The spread of Zika
The Zika virus has been rapidly spreading across Brazil, Central and South America, with some athletes reportedly choosing to pull out of the Olympics Games currently being held in Rio for fear of contracting the virus. Reports also indicate that around 1,650 US residents have so far been infected via mosquito bites sustained on North American soil in recent weeks. Zika has most recently been reported to have reached Miami, Florida – where 15 cases have been confirmed so far. In the UK, according to Public Health England, more than 50 residents have tested positive for the Zika virus in recent weeks, but all are said to have recently returned from travel abroad.
The current outbreak of the Zika virus, first confirmed in March 2015 in Brazil, is transmitted via the bite of two types of mosquito – Aedes Aegypti and Aedes Albopictus (pictured above) – but is also said to be transmitted from person to person through sexual contact. In most people, the virus only causes mild illness with symptoms that include a rash, general malaise, a mild fever, joint pain and headache. Some are said to experience such mild symptoms that they may not even know they have been exposed to Zika at all, however, the effects of the virus on the developing foetus during pregnancy has been closely associated with the aforementioned serious and irreversible birth defects including microcephaly – an under-developed skull and subsequently malformed brain.
Other effects of Zika – Guillain-Barre syndrome
Experts say there is also a growing body of evidence that some people who contract Zika may go on to develop Guillain-Barré syndrome – a post-infection condition of the peripheral nervous system, which causes muscle weakness, pain, fatigue and a characteristic inability to walk or stand unaided. While the effects of the syndrome can be long-term, the majority of people are said to make a full recovery within 12 months with the correct treatment and physiotherapy.
The World Health Organization (WHO) declared the Zika virus a Public Health Emergency of International Concern back in February, and issued a warning that the virus could spread across North America and elsewhere with the potential to infect between 3 and 4 million people over the course of 12 months. WHO described the situation at the time as having moved from a “mild threat” to one of “alarming proportions”.
At last update, 14 countries have reported cases of microcephaly so far, and the first European baby confirmed with the condition was born in Spain in late July. Zika is said to be currently subject to widespread transmission in 43 countries, with a further eight countries reporting sporadic or infrequent transmission.
Zika – the challenge ahead
Professor Jimmy Whitworth, from the UK’s London School of Hygiene and Tropical Medicine, told the BBC that while the observations of Dr Linden and her team were not concrete proof, he describes the evidence that Zika may be to blame as "pretty compelling".
He says: "Microcephaly is the most obvious sign of congenital infection with Zika, but it's becoming clear that's just part of the whole spectrum of damage that can be caused by the virus."
Professor Whitworth says the challenge of stopping the infection in its tracks remains, alongside caring for those who will be affected in the long as well as the short term. He says that the current epidemic could continue for a further three to four years, which could mean tens of thousands of babies may eventually be affected by the Zika virus. He adds: "Meeting their physical and psychosocial needs will be the real challenge."
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