Despite the WHO’s declaration that Zika no longer constitutes an international emergency, seafarers must not lower their guard when visiting an area where there is a risk of exposure to a mosquito-borne disease.
The threat of Zika is not over
In a statement of 18 November 2016, the WHO declared an end to the Public Health Emergency of International Concern (PHEIC) regarding Zika. The urgency underlying the original PHEIC was the necessity to demonstrate the causal link between the mosquito borne Zika virus and extraordinary clusters of microcephaly and other neurological disorders. Once that causal link had been scientifically established, the emergency designation ended. At the same time, the statement also makes it clear that Zika remains a significant and enduring global health threat, see also the Director-General of WHO’s commentary “Zika: We must be ready for the long haul” on 1 February 2017.
Zika has joined the class of mosquito-borne diseases that have the potential to cause severe health implications for seafarers. Other mosquito-borne diseases in this class include malaria, dengue, yellow fever and chikungunya. It is important that shipowners and operators safeguard crew through awareness of recent areas of outbreak of these diseases as well as prevention measures including education of crew.
Mosquito-borne diseases affecting shipping – fast facts
The global burden
Mosquitoes are one of the deadliest animals in the world, according to the WHO. Their ability to carry and spread disease leads to millions of deaths every year. Zika recently emerged as one of the most challenging threats to human health but it is also worth noting that malaria alone caused 438,000 deaths in 2015. The worldwide incidence of dengue has risen 30-fold in the past 30 years, and more countries are reporting their first outbreak of this disease. In its most severe form dengue develops into a potentially lethal complication known as Dengue Haemorrhagic Fever (DHF). In 2015, 2.35 million cases of dengue were reported in the Americas alone, of which 10,200 cases were diagnosed as DHF causing 1,181 deaths. Yellow fever and chikungunya are both diseases that can prove fatal and have both been the cause of epidemics in recent years. Yellow fever is fortunately preventable by an extremely effective vaccine and significant progress in combatting this disease has been made. As for chikungunya, the disease continues to spread but serious complications of this disease are not very common.
Locating the danger
Major trade routes pass through areas affected by mosquito-borne diseases putting seafarers at risk. Exposure to mosquito bites and the resulting rates of infection will vary within a single country and with the seasons. Up to date official advice should therefore be checked every time a vessel is destined for areas where there is a potential risk of mosquito-transmitted diseases. In summary:
The nature of the diseases
The mosquito that transmits malaria, the Anopheles mosquito, is active mainly at night, between dusk and dawn. Zika, dengue, chikungunya and yellow fever, on the other hand, are primarily transmitted through the bites of an infected Aedes mosquito which also bites during daylight hours. Zika can also be sexually transmitted from one person to another.
A seafarer infected by any of the common mosquito-borne diseases may initially experience fever with mild non-specific symptoms similar to those of influenza and other febrile illnesses. However, as severity and treatment varies between the diseases, immediate medical attention should be sought to ensure early diagnosis. Information that may assist in diagnosis has also been published by the WHO and is reproduced below.
Port control measures
Evidence suggests that mosquito-borne diseases spread internationally primarily through infected people. Disinsection of vessels is therefore considered not to be a very effective mechanism to prevent the importation of infected mosquitos (source: EU SHIPSAN ACT “Interim guidance on maritime transport and Zika virus disease”). Nevertheless, some countries may still require proof of disinsection of vessels and/or cargo arriving from affected areas. Disinsection in this case means eradicating live mosquitoes, their larva, and eggs and should not be confused with disinfection.
We have previously reported that both China and South Korea implemented such requirements in March 2016 in order to control Zika virus transmission in to their countries. However, as of March 2017, both countries have announced that disinsection of vessels arriving from Zika affected areas is no longer required. The Korean National Quarantine Station changed its port entry requirements for such vessels on 22 November 2016, immediately after the WHO declared an end to the PHEIC. The Chinese Entry-Exit Inspection and Quarantine Bureau (CIQ) recently announced that, as of 2 March 2017, it will no longer require such vessels to present the “Mosquito Eradication Certificate” upon arrival in Chinese ports, see also Circular No.: PNI1703 from Gard’s local correspondent in China, Huatai Insurance Agency & Consultant Service Ltd.
Changes to yellow fever vaccination certificates
The International Health Regulations (IHR) are an international legal instrument that is binding on 196 countries across the globe, including all the Member States of WHO. Yellow fever is the only disease listed in the IHR for which countries may require proof of vaccination from travellers, including seafarers, as a condition of entry.
Amendments to the IHR entered into force on11 July 2016, and from this date, the certificate of vaccination against yellow fever is valid for the life of the person vaccinated. Revaccination or a booster dose of yellow fever vaccine every 10 years will no longer be required for entry into an IHR State Party and valid IHR international certificates of vaccination are now automatically valid for life of the person indicated. According to the WHO, no modifications are necessary to an existing certificate. Indeed under the IHR, any changes, deletions, erasures or additions may cause a certificate to be rendered invalid. A WHO Q&A provides useful information about the IHR amendments.
Shipowners and operators with vessels trading within mosquito zones should ensure that these vessels are able to deal with the various challenges that a mosquito-borne disease can bring. In addition to the duty of care for those onboard, shipowners and Masters also have a responsibility for taking measures to prevent such diseases from being passed on. Members and clients are therefore advised to, as far as practicable, tailor make their own strategies for dealing with risks associated with mosquito-borne diseases and the following should be considered:
Prior to visiting affected areas
During a visit to affected areas
After a visit to affected areas
Sources of information
Prevention requires vigilance so stay up to date! Here are some recommended sources of information:
National governments may also publish safety alerts concerning seasonal outbreaks of the diseases on their “safe travel” websites. Relevant information can also be obtained from medical doctors and local vaccination offices.
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