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.
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.