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.
Recently I heard from a returned traveller who caught dengue in Sri Lanka. He spent time in hospital and had to prolong his stay there to be well enough to return home. It is important to know that currently there are increased numbers of dengue cases in a number of popular destinations including Sri Lanka. There have been an estimated 61,300 cases of dengue in Sri Lanka since May and nearly 9,000 cases a week are being diagnosed particularly in Colombo and Gampaha districts. The rate is 8 fold higher than average and the outbreak has not yet peaked. In Laos more than 450 suspected cases of dengue per week are occurring primarily in Vientiane and the southern provinces of Attapu and Champasak while in India more than 16,200 suspected and confirmed cases of dengue (significantly higher than usual) have been reported since May 2017 in the south western states of Kerala and Tamil Nadu including in popular destinations. The outbreak has yet to peak. Cases have also been diagnosed in Mombasa, Kenya and American Samoa at increased rates recently. Dengue is spread by daytime biting mosquitoes which are ubiquitous so where ever you are remember to cover up and use repellent to reduce your risk of catching it.
Recently a number of cases of malaria have been diagnosed in travellers returning from Dar es Salaam in Tanzania. Some of those with it were air crew who had only stayed one or two nights in the city during May. The heavy rains in this area may have contributed to the increased risk of malaria transmission. It is really important to remember that in Africa many cities have a risk of malaria and that night time mosquito bite avoidance and prophylacitic medication is needed. Many Asian cities have low risk of malaria but that is not true in Africa.
I have just returned from the 15th Conference of the International Society of Travel Medicine (my 11th one) in Barcelona. A topic we don't think about that was discussed there is Tick Borne Encephalitis. It is a risk in rural parts of Europe and Asia during summer months. The number of cases of it and the areas with it have increased since the 1990s perhaps because of climate change and changing behaviour. It is spread mainly by tick bites but also by eating unpasteurised dairy products especially those made from goat milk. Prevention includes using repellent, wearing permethirn impregnated clothing and checking your body for ticks after being in forested areas. In countries such as Austria 80% of the population is vaccinated against it. If you are going to spend a lot of time in the outdoors in summer months in countries with it you may consider getting vaccinated in Europe on arrival as the vaccine is now hard to get here. You need 2 vaccinations at least 14 days apart.
Measles outbreaks are occurring in Italy and Romania currently. This year there have been over 1,600 cases in Italy and 3,400 in Romania. Thailand and Indonesia are also seeing increased numbers of cases. Travellers returning from both Thailand and Bali have been diagnosed with measles and introduced measles to their home countries this year. It is really important for those born after 1969 to have had 2 doses of a measles containing vaccine.
There is an increase in yellow fever cases in Brazil and they are occurring in areas where it hasn’t been seen before. According to Brazil's Ministry of Health, more than 1,500 suspected and confirmed human cases of yellow fever have occurred mainly in rural eastern municipalities of Minas Gerais State (more than 1,200 cases) and western municipalities of Espírito Santo State (more than 270 cases) since December 2016. The outbreak is past its peak in these areas. Cases have also occurred in other parts of Minas Gerais and Espírito Santo, as well as in São Paulo State, Rio de Janeiro State, and Bahia State. Three confirmed human cases have occurred 135 km north east of the city of Rio de Janeiro. Vaccination campaigns including the city of Rio de Janeiro are under way. Yellow fever vaccination is recommended for travellers 9 months of age and older going to the usual risk areas of Brazil and also new areas including the city of Rio de Janeiro and all of São Paulo State, except for the city of São Paulo. Another change is that Panama, Nicaragua, Venezuela, Costa Rica, Ecuador and Cuba are demanding that people arriving from Brazil present an international certificate of yellow fever vaccination. The certificate was not required by these countries before the outbreak.
It is a little over a year since my last blog on Zika in pregnancy. We have learnt a great deal about it since then. In April last year scientists concluded that Zika in pregnancy may cause microcephaly and other neurological problems including seizures, vision and hearing problems. It is the first virus to be noted to have harmful effects on the unborn baby since the realisation in the 1960s that rubella does. A recent study from America which followed pregnant women who had travelled to Zika risk areas found that overall abnormalities potentially caused by Zika were seen in 6% of the infants and foetuses. The rate was 11% among women exposed to Zika during the first third of the pregnancy but no cases were seen among those who were exposed in the second or third part of the pregnancy. (There were not many women in the study so we cannot assume exposure later in pregnancy is completely risk free.) It is important to note that some of the women with abnormal babies did not have symptoms of Zika.
We are still rapidly learning about Zika and our advice may change but at this stage the advice to for pregnant women to avoid travel to Zika risk areas and for women to avoid pregnancy for 8 weeks after leaving risk areas still holds. Men who have been in Zika risk areas should abstain or use condoms for 6 months after leaving Zika areas to avoid passing it to a partner who may also become pregnant.
It is hard to know the risk of Zika at any destination at any time as it is a very changing picture but a useful website is :http://www.health.gov.au/internet/main/publishing.nsf/content/ohp-zika-countries.htm
You may get resistant bacteria in your bowel during travel and they can subsequently become a problem. If you develop an infection caused by these resistant bacteria it can be hard to treat because not many antibiotics will be effective against them. We have recently learnt that many people going to some destinations such as India and Egypt acquire resistant bacteria. If you get diarrhoea while away the rate of acquisition is higher and taking antibiotics to treat diarrhoea increases the risk further. We are thus discouraging people from taking antibiotics for diarrhoea unless the diarrhoea is severe. It is also worth telling your doctor you have recently travelled if you need to have surgery or get an infection as first line antibiotics may not work.
When entering Tanzania proof of yellow fever vaccination may be required if some one is entering from a country with a risk of yellow fever such as Kenya. People arriving from areas with out yellow fever should not need proof of it. However, a study done last year showed unpredictable checks at borders and even people who were arriving from Europe or Dubai were sometimes checked. Checks were more likely at land borders than at airports and more likely at Arusha than Dar es Salaam and Zanzibar. Consequences of not having a valid certificate or exemption note included fines, clearance after a short discussion, inability to obtain a visa and even vaccination at the border. It seems everyone arriving in Tanzania should either be vaccinated or carry an exemption note. This should be unnecessary for those not entering from endemic countries however after reading the study it seems necessary.
Remember that Zika is a risk in Asia as well as Latin America. This year more than 100 cases have been diagnosed in Thailand and Singapore reported its first locally acquired case in August and now has over 300 cases. Cases have been reported in clusters in Geylang, Bedok, Bishan, Hougang, Sengkang, and Toa Payoh townships. No cases involve the Marina, Central, Orchard, or Tanglin areas. In the States 93 locally acquired cases have been reported from Florida including Miami Beach.
A recent report described transmission of zika virus from a male with no symptoms from the infection to his female sexual partner. Previously we had only seen it passed from men with symptoms from the infection. (So the information in my April blog has been proven to be wrong.) There has also now been a report of transmission from a female to her male partner. The guidelines now recommend abstinence or condom use and avoidance of pregnancy for 6 months for anyone after travel to risk areas for Zika. New Zealand recommendations are available : http://www.health.govt.nz/our-work/diseases-and-conditions/zika-virus#sexual