Brazil has a long history of yellow fever. Since the 1930’s Brazil has not only instigated effective mosquito control measures, but also had very early yellow fever vaccine programmes operating. In the latter decades of the 1900s case numbers had fallen significantly but since the millennium yellow fever has regularly waxed and waned.
This present outbreak, although in its early stages, is already significant because it has affected regions not usually known to be at risk of the disease. The pink coastal areas on the map below are the newly affected regions that have been added to the much larger area of Brazil, coloured red, already known to be at risk for yellow fever.
The major concern is if this emerging epidemic, which may have affected several hundred people so far, is carried to the major Brazilian cities by an infected patient. In this case, local city-dwelling mosquitos may then become infected with yellow fever by biting the yellow fever patient, and go on to infect thousands of others. This sort of transmission, responsible for the global spread of many diseases from dengue to Zika, could transform this current outbreak to a major epidemic.
Unlike dengue or Zika, yellow fever has a high fatality rate for the infected adult. Adopting preventative measures, such as avoiding mosquito bites by the use of DEET containing sprays, is clearly important. Also unlike dengue and Zika, there is an effective vaccine available. Recent production problems have made its availability difficult, but several million doses are said to be ordered for Brazil, where many communities remain unvaccinated despite the risk.
At present, the general recommendation is that travellers and workers should be vaccinated if travelling to areas at risk of yellow fever in Brazil. In this emerging situation, however, if working in Brazil for a significant time, it may be wise to get vaccinated before you leave your home country, despite where you will be working most of the time. If city-transmission does occur, those unvaccinated, on long-term placements, will need to source the immunisation locally, which is likely to be difficult when demand is high. Best to be prepared beforehand. For more information please contact Healix to enquire about our eLearning course on bite prevention for those working abroad.
Europe, South Korea and China
Following the almost weekly reports of outbreaks of bird flu around the globe, it may be difficult to know how significant these epidemics are. They are certainly economically important. Bulgaria has culled 430,000 birds, France 800,000 ducks, whereas South Korea has culled around 30 million birds – during this, their worst outbreak of bird influenza.
As certain avian influenzas are transmissible to humans, a key issue is the sort of virus that has infected these birds. In Europe at present there is an outbreak of H5N8 virus, whereas the South Korean epidemic is caused by H5N6. The WHO describe the risk of transmission to humans as low for the H5N8 virus, interestingly they cite that this virus is not easily transmissible in ferrets – an animal model often used to study human flu transmission.
There have been human cases of H5N6 infections, however – the bird flu currently in South Korea. Two cases of severely ill patients were reported at the end of last year in 2 neighbouring regions of China: Hunan province and Guangxi province. Whilst the facts surrounding these cases are not entirely clear, it is likely that contact with diseased birds had occurred, rather than the patients having acquired the virus from another human: transmissibility between humans is still thought to be very limited with the H5N6 virus.
There has been an on-going transmission of another bird flu in China for the past 4 years. The H7N9 virus has caused over 900 laboratory-confirmed cases and has proved to be fatal in around 20% of those infected. Most of these cases have resulted from discrete infections from infected birds to humans – again human-to-human transmission is poor. A severe pneumonia has often resulted following infection that has necessitated specialised hospital care. The concern is that as the virus mutates, it may become more efficient at spreading from human to human, and be able to start an epidemic. Although there is no particular reason why this should occur, as this eventuality is possible, efforts are being made to characterise how infections are occurring and whether human transmission has indeed taken place.
As with all the bird flus, it is important to avoid poultry farms or markets when working or travelling in China, Cooking food well is important as is washing hands effectively.
The outbreak of hepatitis E that has caused almost 900 cases of jaundice is increasing in Am Tinan, in the Salamat region of Chad. This virus is spread via contaminated water and can be found in areas of inadequate sanitation. This present outbreak, said to be causing 60 cases a week of hepatitis and jaundice, has caused 64 individuals to be hospitalised and has proved fatal for 11 patients. Hepatitis E is particularly perilous for pregnant mothers in whom the case fatality rate is 25%.
Médecins Sans Frontières have sent 600 staff into the region. In conjunction with Chad’s Health Ministry, they are working to improve the diagnosis and treatment of patients, as well as enhance sanitation and access to chlorinated water.
As reported here last year, Angola has been suffering a catastrophic malaria outbreak, and more recently a yellow fever epidemic. As many as 4.2 million cases of malaria have occurred, causing the death of 15,000 patients. The yellow fever outbreak has been on a much smaller scale but has caused 384 fatalities from over 4,000 cases of the disease. Both illnesses are carried by mosquitoes, which have been reported to flourish around the piles of refuse left in the streets, following the reduction in garbage collecting services.
Adding to this plight, are the floods that have recently occurred in Northern Angola, which not only left thousands homeless but which have been followed with an outbreak of cholera. Although the numbers reported in the press vary, around 250 cases of the water-borne illness have been suspected, resulting in 11 deaths. This diarrheal disease can usually be successfully treated in most cases with oral rehydration and replenishment of salts, but great care must be taken not to infect others.
Although the plague is endemic in Madagascar, a recent outbreak is causing concern as it has occurred in a region not usually associated with this serious, ancient illness. Caused by the bacteria Yersinia pestis, when infection of the lung occurs (in the so-called pneumonic form) transmission from human to human by coughing becomes readily possible, which may result in a large outbreak. Only 5 of the 62 cases of the plague reported so far were of the pneumonic form but care is being taken by a multidisciplinary team from the ministry of health and the Institute Pasteur, to identify cases and treat this disease as early as possible.
Written by Dr. Simon Worrell, Head of Medical Communications.