The past influenza season in the northern hemisphere saw very high rates of illness, hospitalisations and deaths. A recent study on influenza showed that on average 1 in 5 unvaccinated children and 1 in 10 unvaccinated adults are infected with seasonal influenza annually. Half of those infected have typical symptoms of influenza. Rates are highest in children, followed by older people, and lowest in adults. Vaccine efficacy varies considerably each season depending on if the vaccine matches the circulating strains well or not. The match for the past northern hemisphere vaccine was not good so protection was estimated to be only 36%. We have a different component in our vaccine for this season and hope it will match the strains we get. I encourage you to have an influenza vaccine and also remember that in the tropical parts of the world influenza circulates year round.
It’s better not to have a live vaccine such as MMR or Zostavax in the month prior to having a yellow fever one
It is better to have live vaccines on the same day or a month apart or else the effectiveness of them may be reduced. Yellow fever is a live viral vaccine and so are the Measles Mumps and Rubella (MMR) and the shingles vaccine (Zostavax). If having either of them please do them at least month before or after your yellow fever one or schedule an appointment with your GP on the day you are coming for your yellow fever one.
Zostavax, a vaccine to reduce the risk of shingles and the pain that may follow shingles became funded in New Zealand from 1 April for those aged 65 years or older so many people are being offered it by their GP practice when having their annual flu one. It is a live vaccine that contains weakened varicella zoster virus (the virus that causes chicken pox and shingles). MMR is also being recommended increasingly as outbreaks occur both here and overseas because of low uptake of the vaccine in some groups and some countries. Remember if having either of them and needing a yellow fever one also think about the timing before going ahead.
Recently WHO proposed new guide lines about rabies vaccinations both before travel (preexposure) and after a mammal bite (post exposure.) They have shortened pretravel/ preexposure vaccinations from 3 doses over a month to 2 doses a week apart. This is cheaper obviously and uses less vaccine (important factors in WHO’s considerations) and easier allowing people to do the 2 doses in only a week rather than a month. The doses may be intramuscular or into the skin (intra dermal) with intradermal needing injections at 2 sites each dose. At the recent Asia Pacific Travel Health Conference in Bangkok it was interesting to hear how other countries are responding to the proposed change. There remains anxiety that while 2 doses get people protected for their upcoming trip the information on how long in to the future people will be boostable (respond to boosters after a bite) is uncertain. It seems at this time doctors in America and UK will continue to give 3 doses pretravel so that people can be sure they are protected for future trips.
There is a network of clinics around the world seeing people who are unwell during or after travel. Information about the health problems travellers need to be seen for at these clinics is collected and analysed. It is notable that 74% of those needing to be seen for medical care after mammal bites had been bitten in Asia (42% in South East Asia and 32% in other parts of Asia.) This compared with only 9% in Africa and 7% in Latin America. Top countries were Thailand, Indonesia, Nepal, China and India. While the data probably partly reflects the numbers of travellers to the different destinations and where the clinics are situated it also clearly shows the higher risk of mammal bites in Asia than other regions. Another study showed that travellers from NZ and Australia departing from Bangkok airport had been bitten more often than people from other countries. This probably reflects that fact that we are not used to thinking about rabies as we are fortunate not to have it here. Remember that mammal bites in most countries are a big nuisance and really try not to play with dogs, monkeys or other mammals. It is a shame that pretravel rabies vaccinations are expensive but they make a mammal bite much less stressful. Certainly consider getting them when travelling to Asia.
Last March I wrote a blog about increased numbers of cases of yellow fever in Brazil including close to Rio de Janeiro. This year Sao Paulo is seeing cases of yellow fever in monkeys and humans and vaccination is now recommended for travellers to all parts of Rio de Janeiro and Sao Paulo states including the urban areas. More than 180 laboratory-confirmed human cases of yellow fever (including 76 deaths) have been reported in the states of São Paulo (80 cases), Minas Gerais (> 45 cases), and Rio de Janeiro (15 cases) and in Distrito Federal (1 case) since July 2017. This is a big increase over normal numbers of cases. In addition, more than 250 confirmed cases of yellow fever in nonhuman primates have been reported since October 2017 throughout forested areas of São Paulo City and in expanding areas of São Paulo Metropolitan Region. Because of this many parks including the zoo and botanical gardens in São Paulo City are closed. Brazil has launched a massive vaccination campaign and hope to vaccinate almost 24 million people in the states of Rio de Janeiro and Sao Paulo in the hopes of preventing an urban outbreak.
Dengue cases are increased In Samoa, American Samoa and French Polynesia currently. So, remember to take repellent and use it to prevent day time mosquito bites when visiting these countries. According to Samoa's Ministry of Health, more than 1,500 suspected and confirmed cases of dengue fever (serotype 2), a significant increase over average incidence, occurred from August to November and high numbers are still being seen. Cases are particularly on Savai'i and Upolu islands, mainly in Apia and the districts of Gaga'emauga and Tuamasaga (Upolu Island). The last dengue outbreak (serotype 3) occurred in 2015-16. In French Polynesia it is dengue 1 circulating currently.
The Pacific has the climate and environment for mosquitos to thrive and movement of people ensures the different strains of dengue virus are introduced regularly to different countries in the region. Dengue, chickungunya and zika are all transmitted by the same day feeding mosquitos which are common in the Pacific so always remember to try and prevent mosquito bites when there.
There have been more cases of plague than usual in Madagascar recently. Low risk always exists throughout most of the country including Antananarivo and Mahajanga but mainly in the central and northern highlands above 800 m. Transmission occurs throughout the year but the highest activity occurs from October to January. There are usually only about 300 cases per year but this year there have been more than 2,300 cases (including 207 deaths) since late August. Cases have been in numerous cities and districts mainly in Analamanga Region including Antananarivo and the city of Toamasina. The last confirmed case was reported on November 21. Public health measures have been increased and screening of departing travellers at airports started. Some countries are screening those arriving from Madagascar. Countries in the surrounding region have had help from WHO to be prepared for cases. The risk to travellers to Madagascar is very low but they should avoid contact with potentially infected rodents and their fleas as well as sick people especially those with a cough.
Travellers who return home to visit family and relations (VFRs) are at a higher risk of health problems than tourist travellers. This is the opposite of what you might expect! They have more malaria, typhoid, sexually transmitted infections and parasitic infections. There are a number of reasons for this but often VFR travellers go for longer and stay in more rural areas and mix with local people more often than other tourists. In addition they are less likely to have pretravel medical advice thinking that it is not necessary when in fact it is more important for them. Often protection against things like malaria and diorrhea is lost when you live in areas free of them such as New Zealand. This makes VFRs like vunerable babies when they go back home. So if you or your children are going back home it is really important to get pretravel health advice and vaccinations and to take precautions when there.
Recently the price of this vaccination dropped which was a surprise and great news. Japanese encephalitis is a virus spread by evening and night time feeding mosquitoes in rural parts of Asia . The risk areas extend from Japan and Korea to Pakistan and down to Papua New Guinea. The infection often does not cause symptoms but a few who are infected develope encephalitis (with symptoms such as changes in thinking, weakness, paralysis and seizures) which may be fatal or leave lasting neurological damage. In affected countries children are most commonly affected although travellers of any age may catch it. In the cooler parts of Asia tranmission is greatest in the summer months. In the tropics and subtropics risk varies with rainfall and irrigation practices and may be year round. Pigs and wading birds may carry the virus so the risk to humans is higher where they are found. The vaccine requires 2 doses which were previously given 28 days apart but studies have recently shown that having them as close as a week works well too. It is always hard to know when to have the vaccination and the decision is an indivdual one as it depends on your itnerary and activities. Reducing evening and night time mosquito bites reduces your risk but the vaccination should be considered by those with time in rural or agricutlural areas particlualry if doing outdoor activities or staying in accomdation without airconditioning or screens or nets.
Ciguatera fish poisoning (CFT) seems to be increasing in its global spread. It is a collection of symptoms which occur after people eat fish with ciguatoxin. The toxin is made by dionflagellates in shallow coastal regions such as reefs and atolls. The toxin goes up the food chain from herbivorous to carnivorous reef fish such as barracuda and grouper. It is tasteless and odourless and not destroyed by cooking or freezing the fish. Within minutes to 12 hours of eating contaminated fish people may get nausea, vomiting and diarrhoea followed over the next 48 hours by neurologic symptoms such as burning or tingling sensations in the hands, feet and possibly mouth; itch; sore muscles or joints; dizziness, fatigue, anxiety and the reversal of heat and cold sensation. It has occurred in the Pacific and Caribbean for many years but is now being seen in previously unreported areas such as the western Gulf of Mexico, eastern Mediterranean, Crete, Brazil, Hong Kong, Thailand, and West Africa (eastern Atlantic.) You can reduce your risk of getting ciguatera poisoning by checking with locals about its presence and not eating large amounts of reef fish particularly the brain or organs which are more likely to have the toxin.