Democratic Republic of Congo
The recent outbreak of Ebola in the Democratic Republic of Congo has provoked global attention unseen during its previous epidemics in the same country. For the DRC, this is the 8th occurrence of the severe viral illness since 1976, when 318 cases were reported. Of course this heightened attention to Ebola follows the 2014 West African outbreak that affected almost 30,000 people, killing over 11,000.
One of the principle reasons why the 2014 epidemic was so much larger than any previously seen in Africa, was that the first cases occurred over the borders of several countries not known previously to have had Ebola. Furthermore, the cultural practices that facilitated the transmission of the virus, such as the ritual washing of the deceased that occurred during traditional burials, proved difficult to eradicate. Added to this was the distrust and fear of western aid workers, who were often blamed for the epidemic or for taking away sick loved ones, who never returned to their families. Such mistrust led to the late adoption of health advice and the failure of notifying healthcare workers when family members, especially children, became ill. All of these factors added together to fuel the epidemic, stoking the number of those affected, and those that died.
All of these obstructions to public health in West Africa, very understandable in the face of such a catastrophe, had been seen before and overcome during previous epidemics of Ebola in Central Africa, however. The present outbreak in the DRC is very unlikely to produce such case numbers as were seen in 2014, as the local population is sadly all too aware of Ebola and its historical solution: quarantine.
Some aspects of this outbreak are new, however.
Following criticisms of their response during the West African epidemic, the WHO and partners have responded impressively swiftly following the notification of a cluster of undiagnosed illnesses in a remote part of the DRC on the 9th May. In fact the very next day saw a multidisciplinary team, led by the DRC Ministry of Health, being sent into the affected region. In addition, the promising Ebola vaccine by Merck, rVSV-ZEBOV, has been given approval for use in the DRC. Although its abilities to stave-off Ebola infection need further clarification, the vaccine might be used in cases where the chain of infection is unclear; where contacts of an unexplained Ebola patient can be vaccinated to prevent further transmission. This is the so-called ‘ring’ strategy, where a ring of protected contacts surrounds an infected individual.
There are several logistical challenges involved with such a vaccination programme: contacts must be identified and inoculated swiftly before they do get infected with Ebola and the vaccine is given too late. Moreover the vaccine itself must be stored at minus 80 degrees C; at Congolese room temperature, the vaccine becomes useless after only one day.
Suspected cases of anthrax have been reported in the Thika region of Kenya recently. Eight abattoir workers were admitted to hospital with symptoms suggestive of the disease, but have subsequently been discharged following treatment. Anthrax is caused by the spores of the bacterium Bacillus anthracis and most commonly causes a skin infection – which seems to have been the situation with the recent Kenyan cases. This is the mildest form of the disease and is usually easily treated with a course of antibiotics. If the spores are eaten or inhaled, however, the outlook can be particularly grave: without treatment the mortality rate can be as high as 60% to 90%.
Anthrax was last widely reported following the infection of 100 people in the summer of last year. The particularly high temperatures in the Siberian tundra thawed long-frozen reindeer that were infected with anthrax spores. The local human inhabitants became infected following anthrax being transmitted to the living reindeer population, which is an important source of food – 2,300 reindeer died of anthrax during that epidemic, and another 100,000 were culled. The ability of anthrax spores to survive in challenging climates, for many decades, has led to some dubbing the bacteria as almost indestructible.
The global spread of the Zika virus has been expected to mirror certain other diseases also transmitted by the Aedes mosquito. This mosquito, present throughout the tropical and sub-tropical globe, is responsible for spreading a range of illnesses, from dengue and chikungunya to yellow fever and the ‘newer’ Zika virus.
Following its emergence in South America, Zika spread to South-East Asia in 2016. As India has recently suffered large epidemics of both dengue fever and chikungunya, many thought it was just a matter of time before Zika would affect this country of 1.3 billion people. The recent report from the WHO confirms that Zika has indeed now spread to India as 3 cases have been identified, all from a single medical facility in Ahmadabad.
There are several interesting features of this report, however. Firstly, these infections occurred some time ago: 2 cases from November 2016 and 1 from January of this year, leading to some speculation as to the cause of the delay in notification and the possibility of a cover-up. Secondly, two of the Zika-positive samples were from pregnant women: one positive result came from a routine screening and the other from a recent mother who had serendipitously developed symptoms of a viral infection in hospital – and so was tested. Taking all these factors together, it seems very likely that there have been many more Zika infections in the area, and the true number of Zika infections remains unknown.
It is not certain at present why some countries have had higher complication rates from Zika; Brazil for example has reported thousands of cases of microcephaly, but some countries have reported few such complications. One suggestion is that another factor may be required in addition to the Zika virus to produce these devastating complications. This so-called Zika-plus theory has several candidates for the extra factor required, but the most likely factor needed may be prior infection with the dengue virus. As India has had large recent dengue epidemics, there is a chance that the population may already be primed for complications following a Zika outbreak. This is the fear that has concerned many who have seen the transmission of Zika to India as somewhat inevitable. Let’s hope we are wrong.
Written by Dr. Simon Worrell, Head of Medical Communications.