It is unlikely anyone has missed the headlines on the mosquito-borne Zika virus, particularly its possible link to babies born with microcephaly. With a growing number of cases of the virus in the Americas and the Caribbean, and instances now confirmed in Europe, Dr Lisa Bushby explores what employers can do to keep their employees safe at work.
The Zika virus is generally transmitted by mosquitoes. According to the World Health Organization (WHO), the symptoms of Zika virus disease are similar to those seen with dengue fever: fever, skin rashes, conjunctivitis, muscle and joint pain, malaise and headaches. The symptoms typically last around two to seven days.
Infection with the Zika virus can only be diagnosed in the laboratory. There is currently no vaccine available.
Potential complications are cause for concern. Local health authorities in Brazil have observed an increase in Guillain-Barré syndrome, where the immune system attacks the nervous system, causing temporary weakness and even paralysis. Perhaps most alarming, there is also an associated rise in the number of babies born with microcephaly in Brazil. Microcephaly is a rare condition where a baby is born with a smaller than average head size or where the head stops growing after birth. If this combines with poor brain growth, babies with microcephaly can have developmental disabilities.
While there is growing evidence of a relationship between Zika and microcephaly, the link is not yet scientifically proven. Nonetheless, the causal relationship established so far is strong enough that the UK Government is advising women to avoid becoming pregnant while travelling in an area with active Zika transmission and, on returning to the UK, avoiding becoming pregnant for a further 28 days.
Women who are pregnant or planning to become pregnant may therefore have understandable concerns about any travel to an area with active Zika transmission. Employers should be sensitive to this by identifying other individuals to travel in their place, if necessary.
Contact with the Zika virus
The UK Government has announced funding for research to tackle the Zika virus, meaning that it is possible laboratory workers in the UK may intentionally come into contact with it through their work. In other cases, healthcare workers may come into contact with the virus through patients who have Zika.
While mosquitoes carrying Zika are extremely unlikely to survive and breed in the UK, there may be some risk to those working in ports that receive cargo from affected countries — it is also possible that these workers could come into contact with sick seafarers.
The more obvious risk to UK workers is to any employees travelling for work to any of the areas that have active Zika transmissions, as they may become infected through contact with mosquitoes. Before sending employees abroad, employers should check the travel advice for countries reporting active Zika transmissions at the travel health pro website.
Control of infection
The principal legislation that applies in relation to Zika in the workplace is the Control of Substances Hazardous to Health Regulations 2002 (COSHH). These cover hazardous substances, including biological agents. COSHH requires employers to assess the risks of exposure to biological agents and either prevent exposure (where reasonably practicable) or control it adequately.
The process of infection can be represented as a chain from source to transmission to host, where any break in the chain will control the risk of infection.
In terms of Zika in the workplace, the source will be the virus itself, the transmission could be through a needlestick injury, and the host would be the laboratory or healthcare worker.
Both laboratories dealing with pathogens and healthcare environments are likely to be familiar with these routes of transmission. Employers should put the usual control measures in place following a suitable and sufficient risk assessment, such as a requirement to cover any cuts or grazes on the skin with a waterproof dressing. Suitable personal protective equipment (PPE) such as disposable gloves, eye protection, aprons, face shields should be available, and facilities should be provided for frequent hand washing.
In terms of contraction of Zika through travel to an active Zika virus transmission area for work, the source would be a mosquito carrying the virus, the transmission route a bite and the host would be the person being bitten.
Employees should be given awareness training regarding the virus ahead of any international travel and the following precautions against being bitten by a mosquito should be taken.
Use insect repellent in accordance with the label instructions: repellents may be applied to exposed skin or to clothing, and should contain N,N-diethyl-m-toluamide or N,N-diethyl-3-methyl-benzamide (DEET).
Wear long-sleeved, full length, light-coloured clothes that cover as much of the body as possible.
Use physical barriers such as screens, doors and windows and mosquito nets. Mosquito nets can be treated with DEET insect repellant and if they do not reach the floor can be tucked under the mattress.
Be aware of the danger period — mosquitoes are usually most active at dawn and dusk, but the Aedes mosquito that spreads the Zika virus bites mostly during the daytime.
Employees showing symptoms of dengue fever or the Zika virus within three weeks after returning from an affected area should contact a healthcare professional. Pregnant women who have travelled to areas with Zika virus transmission should mention their travel during antenatal visits in order to be assessed and monitored appropriately.
It should be noted that as a precautionary measure, the UK Government is asking airlines to spray insecticide inside aircraft used for flights to the UK from countries with confirmed transmission of Zika, to reduce the risk of passengers being bitten by any mosquitoes that could have entered the aircraft.
Finally, there have been suspected cases of sexual transmission from men carrying the virus so barrier precautions are recommended. Zika has been detected in breast milk, but there is currently no evidence that the virus is transmitted to babies through breastfeeding. Current WHO breastfeeding recommendations remain valid, in particular exclusive breastfeeding for the first six months of life.
Infection at Work: Controlling the Risks. A Guide for Employers and the Self-employed on Identifying, Assessing and Controlling the Risks of Infection in the Workplace (2003), Health and Safety Executive. Available from the HSE website.
Rapid Risk Assessment: Zika Virus Disease Epidemic: Potential Association with Microcephaly and Guillain-Barré Syndrome (2016), European Centre for Disease Prevention and Control, available from the ECDC website.
Zika Virus Factsheet (2016), World Health Organization, available from the WHO website.