A game hunter in his mid-30s from the Kween district in Uganda became critically unwell in September of this year. The patient was subsequently diagnosed with Marburg disease. As the natural host of the virus that causes Marburg is the Rousettus bat, the patient may have caught the viral infection by visiting a local cave that is said to be bat-infested.
Marburg is an extremely serious illness similar in many ways to the Ebola virus, causing uncontrolled bleeding as the disease progresses and producing a very high fatality rate. In this case, the Ugandan man sadly passed away shortly after becoming unwell, and subsequently received a traditional burial attended by around 200 people. As has been highlighted during the West African Ebola outbreak, traditional burial practices are implicated in the human-to-human spread of the disease, as close contact with the highly infectious corpse usually occurs when the body is prepared for the ritual.
Two further fatalities have now followed; both were family members of the initial patient. In another echo of the recent Ebola outbreak where hospital staff were at particular risk of becoming infected, a contact of the Ugandan patient became ill on the 4th November and admitted to a facility in Kween – a healthcare worker.
Since this outbreak is occurring in regions bordering Kenya, particular urgency is being placed in tracing contacts of the deceased individuals. The WHO report that some contacts have already travelled to Kenya, and another person to Kampala. Many of the contacts have already passed the 21 day mark, however, after which they were deemed uninfectious as they failed to develop symptoms.
As with previous epidemics of Marburg and Ebola, obtaining the help and trust of the local community is of paramount importance: ill patients must be identified, quarantined and treated; practices that spread the outbreak such as traditional burials must be stopped. The WHO had initially reported that there was significant local resistance to their approaches but following consultations with community leaders, co-operation is starting to occur. If contact tracing is successful, isolation of potential cases occurs, and traditional practices halted, then the outbreak may soon be controlled. But the epidemic is still in its early stages at present.
The number of cases of plague has been far greater than normal in Madagascar this year. Suffering around 400 cases in a usual year, Madagascar has seen the number of patients infected with the plague already reach over 2,000. The WHO have pointed out that as the usual ‘plague season’ runs to April 2018, the number of cases is expected to increase – but at a much reduced rate.
The numbers of cases had been dramatically increasing recently due to the infections being predominantly of the pneumonic form. This allows for rapid human-to-human transmission, as a patient’s infected respiratory droplets are inhaled by others, causing a disease that is fatal if not promptly treated with antibiotics.
In fact many patients start developing symptoms only 24 hours after being infected. This is very fast for a bacterial infection. It does mean, however, that unlike diseases such as Ebola, there is not a three week incubation period during which a seemingly well person can unwittingly pass on the infection to others. With HIV disease, the ‘incubation period’ or at least the time when the patient may not know that they are infected, can be as long as 7 years, potentially allowing for transmission to many individuals. This is certainly not the case with plague.
Another issue that is affected by a short incubation period is the likelihood that travellers, infected but well, can travel by air to other countries and seed a new epidemic. Although 10 countries have now been identified as being at increased risk of receiving plague patients in this way, it is unlikely that in the short 24 hour window between infection and becoming unwell, air travel will be possible. To aid detection of cases, exit as well as entry screening procedures have been instigated at some airports that should be effective.
As for the present outbreak, the WHO and partners are treating contacts of the known cases of plague with a week’s course of antibiotics to prevent any disease from developing – 7,000 people have been treated so far.
Nigeria has an emerging outbreak of monkeypox. This disease, often described as a mild form of small pox, has been confirmed in 38 patients so far, but a larger 116 people are suspected of the disease, coming from 20 states across Nigeria. First starting with a flu-like illness following 2 weeks after infection, a facial rash usually develops that then spreads to the rest of the body. Like chickenpox, vesicles then develop, but with monkeypox the vesicles are larger and the complications more frequent. Death rates have been seen to be as high as 10% in some outbreaks if lung or brain infection occurs. Those most severely affected are children and those from Africa – although the reasons for this are unclear at present.
The severity of a monkeypox outbreak may be linked to the local rate of smallpox vaccination, as many think that the smallpox vaccine might offer some protection against monkeypox. In fact, authorities have highlighted the recent decrease of the uptake of smallpox vaccination in Nigeria, to the increase in monkeypox. Furthermore, the CDC advocated the use of the smallpox vaccine during the outbreak of monkeypox in Midwestern US in 2003.
During the 2003 American outbreak, affecting 50 people, no fatalities were seen. In this instance, close contact with prairie dogs was shown to be the cause of the epidemic. These animals, more squirrel than dog but with a characteristic ‘bark’ perhaps giving rise to their name, had become infected with monkeypox whilst being housed by an animal supplier. In fact, monkeypox-infected Gambian rats had been kept in close proximity to the pet prairie dogs – which subsequently became infected. After the sale of the pets, their human owners also became infected following caring for the animals. Human to human transmission has been described with monkeypox but this appears not to have occurred considerably in the US epidemic – whether this will be important in the emerging Nigerian epidemic is as yet unclear.
Written by Dr. Simon Worrell, Head of Medical Communications.