In our October World Health Report, Dr Adrian Hyzler comments on current epidemics and outbreaks of infectious diseases causing concern to business travellers across the world.
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Ebola Virus Disease in the Democratic Republic of Congo
Death toll surpasses 2,000
As the second largest outbreak of Ebola Virus Disease (EVD) in history moves into its second year, the number of cases in eastern Democratic Republic of Congo (DRC) have risen above 3,000, with more than 2,000 deaths. So far the disease has been almost exclusively confined to the DRC. There is some guarded optimism as case numbers have remained stable over the last few weeks with no increase in growth of cases.
There were three deaths in Uganda in June, all from the same family that crossed the border with DRC to attend the funeral of a relative who had died from EVD. On their return they developed symptoms and were immediately isolated in an Ebola Treatment Centre (ETC), but sadly they died of the disease. However, excellent preparedness and successful screening centres combined with rapid action by the public health authorities contained the disease with only one further death recorded – a nine year old child, once again arriving from DRC.
Rwanda shares a porous border with Goma, a major transport hub in eastern DRC. There have been a handful of cases in Goma to date, but so far no cases have crossed the international border with Rwanda. Southern Sudanese authorities to the north of DRC maintain that they have adequate border screening facilities to identify any active EVD cases at checkpoints. However, it is not clear that they would be capable of containing spread if infected persons, especially in the early stages of disease, were to enter the region.
Suspected cases in Tanzania denied by Tanzanian authorities
Tanzania has insisted that it has no suspected or confirmed cases of EVD, despite unofficial reports to the World Health Organisation (WHO) that there has been one suspected fatal case in Dar es Salaam, and two others under investigation. The fatality is thought to be a woman who had travelled to Uganda to conduct health research and had visited several health facilities – she then returned to Tanzania and died on 8th September. Tanzania claims that all tests were negative for EVD and that the death was from an unrelated viral cause. However, they have declined to share clinical data and samples with international bodies. Under international health regulations all countries are obliged to cooperate with international health bodies “to protect national citizens as well as all people in the region”. The ramifications from an international perspective, both to the citizens of any country and to their tourist industry, of declaring the first spread of EVD to that country cannot be downplayed.
However, the WHO plays a vital role in the overall organisation and administration of the response to any disease outbreak and they cannot distribute resources or assess risk unless they have full disclosure from national authorities. Despite open questioning from the WHO and the US Health Secretary about the authenticity of the claims, Tanzania continues to deny any cases of EVD.
In July, in response to the cases in Goma, the WHO declared the Ebola crisis in DRC to be a “public health emergency of international concern”. There are currently no other active cases outside DRC, reported to the WHO.
However, a suspicion of health workers and widespread security issues still threaten the fight against the tenth outbreak of EVD in DRC, in a region where armed groups have fought for decades over the mineral-rich land, creating a long-standing humanitarian crisis. The head of the United Nations has reassured the DRC government that support will continue for the army in its fight to gain control of the region – there are currently 16,000 peacekeepers deployed in the country, with an annual budget of more than one billion dollars.
Second vaccine given approval in DRC
Up until now the health authorities in the DRC have relied exclusively on the Merck single-dose vaccine rVSV-ZEBOV, developed following trials on 16,000 volunteers during the 2013-16 Ebola epidemic in west Africa. It is administered as a single dose using a ‘ring vaccination’ technique that radiates out from a known EVD case, to circles of potential contacts. Each operation averages just over 100 people. It has been reported by the DRC authorities that it has been given to 225,000 people since the outbreak was officially declared in August 2018. However, distribution has been hampered by limited supply chain issues and its use has been restricted to health workers and direct potential exposures. Despite the estimated efficacy of 97.5%, its use has not stopped the outbreak.
Consequently, there have been growing calls for the introduction of a second vaccine. This would be used to complement the original vaccine by increasing the depth of the ring of vaccinations. Since vaccines can only be trialled in outbreak situations, experts have warned that unless the J&J vaccine is used now, there can be no way of advancing the prevention of the current and future outbreaks. The vaccine is already in use in neighbouring countries to protect their health workers in ETCs and the manufacturers claim to have one and half million doses ready to be deployed.
The major drawback of the second vaccine is that it needs to be given in two doses at least 25 days apart. In the setting of healthcare workers, this is not such a problem, but when given in the community against a backdrop of mistrust and population displacement, it is much more problematic to ensure follow up for the second vaccine.
The J&J vaccine will be used from October in areas where Ebola is not actively spreading.
Malaria in Burkina Faso
New release of genetically modified mosquitos take fight against malaria
Burkina Faso has taken the fight against malaria into a new arena. Scientists in Burkina have developed and released thousands of genetically altered mosquitoes that are unable to breed.
The mosquitoes are modified using a technique called a ‘gene drive’, which edits and then propagates a gene in a population – the aim is to prevent males from producing offspring. The mosquitoes are injected as embryos with an enzyme that sterilizes them. The enzyme targets only three of the 3,500 species of mosquito worldwide, with the aim of reducing the density of those mosquitoes. Such experiments in the laboratory have been successful in wiping out populations of mosquitoes within 11 generations.
This is not the first such experiment in controlling mosquito populations. Researchers in Brazil have also released genetically modified mosquitoes in an attempt to control diseases like yellow fever and Zika, but it is not clear how effective that has been.
Target Malaria is also developing an enzyme that prevents male mosquitoes from passing on the X chromosomes. This results in exclusively male offspring, thus reducing malaria transmission since only female mosquitoes bite – males mostly feed off plant honeydew.
Despite organisations such as the Bill and Melinda Gates Foundation funding huge investments in bed nets, anti-malarial drugs and insecticides that have slowed malaria over the past two decades, there were still more than 400,000 deaths in 2017. As these traditional tools stall, there is an appetite to try new approaches.
Measles in Europe
Four European nations have lost their measles eradication status.
The United Kingdom, Greece, Albania and the Czech Republic have all lost their eradication status, despite having extremely high vaccination coverage. Countries are declared measles-free by the World Health Organisation when it can be shown that there has been no endemic transmission for 12 months in a specific geographic area.
However, the coverage has been allowed to drop in specific communities and this has allowed measles to spread unchecked in these areas. Worldwide there has been an increase in cases of measles infections- overall, numbers are three times up on last year’s equivalent figures. The US, for example, has registered its highest number of measles cases in 25 years.
The Democratic Republic of Congo, Madagascar and Ukraine in particular are suffering the largest outbreaks of measles around the world.
Austria and Switzerland, on the other hand, attained eradication status this year, bucking the worldwide trend.
Measles is an extremely contagious and potentially fatal illness that causes a rash, cough and fever.
Adequate prevention of spread can be achieved by two doses of the MMR vaccine (measles, mumps, rubella) given at 12 months of age and before starting school. A global movement of a small proportion of influencers who spread an anti-vaccine message has contributed to the reluctance of some parents to vaccinate their children. This in turn has reduced the general level of immunity in the community that serves to protect the majority (known as ‘herd immunity’).
Polio in Ghana
Risk assessment underway as Ghana reports new outbreak of circulating polio virus
Polio virus can be transmitted in two ways. Firstly, by the presence of the virus in the general population through inadequate penetration of a national immunisation schedule in childhood. Polio remains endemic in three countries: Nigeria, Pakistan and Afghanistan. This is known as ‘wild poliovirus’.
In all other countries, outbreaks are caused by circulating ‘vaccine-derived poliovirus’ (cVDPV) – this occurs in populations that are inadequately vaccinated and where sanitation and personal hygiene is poor. Like wild poliovirus, VDPV has the potential to cause paralysis in unvaccinated or partially vaccinated individuals.
A two year old child from Andonyama, a sub-district of Chereponi in the Northern Region of Ghana, developed an acute flaccid paralysis in July 2019 – this was later confirmed as cVDPV type 2. This is the first case of cVDPV reported in Ghana and it follows a confirmed routine environmental water sample collected the previous month in Tamale Metropolis in northern Ghana. Another environmental sample tested positive for the same strain in Accra in August. These all appear to be related to the strain of cVDPV that emerged in Jigwa State Nigeria and subsequently spread to other parts of Nigeria.
Guided by WHO protocols, a risk assessment is underway and an outbreak response is being considered, while neighbouring countries have strengthened their routine surveillance.
Eradication of cVDPV is an important part of the strategy to end polio transmission globally.
Circulating VDPV can be transmitted via the faecal-oral route, through exposure to water contaminated by infected human faeces, or by direct person to person contact. Strict food, water and personal hygiene should be practised and all travellers to Ghana should be up-to-date with routine vaccinations, and should have a polio booster vaccine if the last dose was given 10 or more years ago.
Zika in Cuba
How did Cuba “escape” the Zika outbreak in its peak in 2017?
There were an estimated 800,000 people infected with the Zika virus at the height of the epidemic in 2015 and 2016. The illness that first came to the world’s attention in Brazil in 2015 spread rapidly through the Americas and the Caribbean. The devastating effect of the flu-like virus was to leave nearly 4,000 newborns with serious brain damage. As quickly as it descended on the region, by mid-2017 it seemed to disappear. In the meantime in February 2016, the WHO had declared Zika to be a Public Health Emergency of International Concern (PHEIC). This emergency was lifted nine months later, as numbers of cases fell.
Cuba did not report any cases of Zika to world health officials at the time when the country’s outbreak apparently peaked in 2017. Epidemiologists have calculated that 98% of Zika-infected travellers who returned to the US or Europe in 2017 had visited Cuba. Computer modelling estimates that Cuba had around 5,700 unreported cases, in 2017. This would be in line with other similarly populated Caribbean islands.
Intriguingly, it seemed that the virus emerged in Cuba about one year later than elsewhere in the Caribbean.
It now emerges that this was the result of an aggressive centralised pesticide spraying campaign, instigated soon after Zika hit the headlines, in an attempt to control the Aedes aegypti mosquito – the ‘vector’ that transmits the Zika virus. This also resulted in a sharp decline in cases of dengue fever, also transmitted by the Aedes vector.
By the end of 2016, Cuba had confirmed only 187 cases of Zika, and it stopped reporting numbers altogether in 2017, in line with the relaxing of reporting obligations once the WHO dropped the declaration of PHEIC. It reported no cases of Zika-related brain damage to babies.
Cuba managed to halt the emergence of Zika while numbers of cases in neighbouring countries were peaking and by the time the virus emerged in Cuba a year later, attention had shifted from the world’s gaze. Gene sequencing techniques were used by a group of epidemiologists to pin-point the viral sequences from travellers and thus produce a surveillance map retrospectively. It is hoped that such techniques can be used to help clarify the course of epidemics that might otherwise have escaped surveillance.
Yellow fever in Nigeria
Further yellow fever outbreaks reported as death toll rises
There have been further reports of outbreaks of yellow fever in Nigeria. The latest area affected is the Alkaleri Local Government Area (LGA) in Bauchi State. This follows previous reports of cases in four other states: Borno, Gombe, Kano and Katsina. Over the last six weeks there have been 34 deaths reported.
Yellow fever is transmitted by the infected Aedes mosquito that also carries dengue and Zika, among other infections. It causes an acute viral haemorrhagic disease – it takes between three to six days after being bitten before symptoms develop (the ‘incubation period’). Many people remain symptom-free, but when these do occur, the most common are similar to a flu-like illness: fever, muscle pain with prominent backache, headache, loss of appetite, and nausea or vomiting. Usually these symptoms disappear after three to four days. A small percentage of patients, however, enter a second, more toxic phase within 24 hours of recovering from initial symptoms. High fever returns and organ failure develops, in particular liver and kidney failure. The accompanying jaundice that manifests itself as yellowing of the skin and eyes, gives the disease its name. Dehydration puts a strain on the kidneys and causes dark urine and abdominal pain with vomiting. Bleeding can occur from the mouth, nose, eyes or stomach. Half of the patients who enter the toxic phase die within seven to 10 days.
The risk of transmission is present throughout the country and all travellers, over the age of nine months, are advised to ensure that they have had the yellow fever vaccine – the WHO recently changed the recommendation for a booster every 10 years, and now a single dose is assumed to confer life-long protection. It is always advised that bite prevention measures should be practised between dawn and dusk, when the Aedes mosquito is most active. Of course, it is recommended that bite prevention should be maintained at all times, in order to cover the other threat from the anopheles mosquito that transmits malaria.
Infectious Disease and Business Continuity for your Organisation
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