Adam MacNeil; Pierre E. Rollin

“ Large outbreaks of EHF in the Democratic Republic of Congo (DRC) in 2007 and 2008, and in Uganda in 2007 [8] – [9] , have demonstrated the continued potential for prolonged virus transmission in impoverished rural communities. We will discuss the epidemiology and control of EHF and MHF, relative to the concepts of neglected tropical diseases (NTDs) .
Epidemiology of Ebola and Marburg Hemorrhagic Fever
EBOV and MARV are zoonotic viruses, and outside of outbreaks, do not persist in human populations. ”

“ As noted above, a common characteristic of large EHF and MHF outbreaks is the break-down (or absolute lack of) public health surveillance, resulting in long periods of time before identification of the outbreak by public health authorities. With improved surveillance, early chains of transmission can be identified and outbreak response efforts rapidly applied. As an example, during the recent reemergence of EHF in Luwero district, Uganda (May 2011) , viral hemorrhagic fever was immediately suspected in the index (and only case) by clinicians at the hospital. ”

“ Given the nature of the spread of EBOV and MARV in outbreak settings (chains of person-to-person transmission) , the efficacious outbreak control measure already developed (contact tracing, isolation, and safe burials) , and the scope of even the largest outbreaks (Gulu, Uganda in 2000 with 425 EHF cases is the largest known outbreak) , the application of mass vaccination would not be an efficient or cost effective control mechanism, and would likely draw resources and public personnel away from outbreak control activities. ”

“ A final strategy, in the instance of a vaccine or anti-viral drug with the potential to prevent or minimize severity of disease, would be to apply these measures to high risk contacts of suspected or confirmed EHF or MHF cases, as well as to those who are already ill (and in isolation) . This activity, if measures can be administered early enough to be effective, would inevitably save lives and would be an incentive for suspected patients to enter isolation. ”

“ Additionally, if vaccine is administered to an exposed individual during the incubation period and disease subsequently develops, there is a risk that those administering the vaccine will be perceived by the local population as spreading the disease, which would undermine efforts to further implement vaccination or other control methods. ”

“ However, from an outbreak control standpoint, a symptomatic individual tracked through contact tracing activities is in essence removed from the “transmitter pool”, and shortly after onset of symptoms (and infectiousness) will be placed under safe isolation for proper medical care. Similarly, sick individuals, already in properly managed isolation, would not further propagate the virus. Thus, while having potential therapeutic value, post-exposure biologics may have limited impact on the scope of EHF or MHF outbreaks. ”

“ Because EBOV and MARV transmission occurs through direct physical contact with an infected person, bodily fluids, or through contact with contaminated clothes or linens, transmission to health care staff and patients can largely be controlled through implementation of barrier nursing practices for individuals with hemorrhagic symptoms and ensuring that needles or other medical equipment that may contain contaminated fluids are not reused. ”

“ While in a rural area, Luwero is located less than 2 hours by vehicle from the capital of Uganda (Kampala) . A confirmatory laboratory diagnosis was acquired in less than a week, and outbreak response activities commenced within 24 hours [62] . While contacts of this EHF case fortunately did not develop disease, the ability to identify and follow-up all contacts would have resulted in prevention of further spread of the virus, should secondary cases have developed.
Public health approaches for NTDs have traditionally focused on vertical drug-based treatment strategies [41] , [42] . ”

“ Beyond the deaths of specific individuals, outbreaks have also had severe effects on the actual functioning of medical services. For instance, the Kikwit, DRC, EHF outbreak in 1995 resulted in the infection of 80 health care workers and the closure of Kikwit General Hospital for non-EHF related activities, severely limiting the availability of medical care to the population of Kikwit (200,000) , as well as surrounding areas [22] , [23] .
An additional defining characteristic of the 13 NTDs is the absence of an available vaccine [59] . Moran et al. ”

“ Additionally, while the zoonotic source of exposure is not always identified in outbreaks, introductions of these viruses to human populations have been associated with entering caves and mines (for MARV) and hunting for or processing bushmeat (for EBOV) [30] – [31] . ”

“ Although EHF and MHF may not have the regional or national poverty-promoting effects as some NTDs, the local effects of an outbreak on a village, town, or region can be devastating. Tens to hundreds of deaths have occurred in previous outbreaks. ”

“ Libande, ML & Tshomba, A, “Serosurvey on household contacts of Marburg hemorrhagic fever patients.”, Emerg Infect Dis 12: 433–439, pmid:16704781 ↑ Bausch, DG, “The Ebola Virus ...... and the Challenges to Health Research in Africa.”, United Nations Chronicle 38: 6–13 ↑ Accorsi, S; Fabiani, M; Nattabi, B; Corrado, B & Iriso, R, “The disease profile of poverty: morbidity and mortality in northern Uganda in the context of war, population displacement and HIV/AIDS.”, Trans R Soc Trop Med Hyg 99: 226–233, pmid:15653126 ↑ Bethony, JM ”