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Marburg Hemorrhagic Fever Outbreak in Angola – 2004-05
Lynn M. Little, PhD, CLS(NCA)
Chair, Microbiology Scientific Assembly
Professor and Chairman
Department of Medical Laboratory Sciences
The University of Texas Southwestern Medical Center at Dallas
Viral hemorrhagic fevers. Viral hemorrhagic fevers are severe illnesses caused by a number of viruses categorized in several different virus families. All viral hemorrhagic fevers are characterized by multiple organ system involvement, collapse of the vascular system, severe prostration, and high mortality. Specific signs and symptoms vary, but patients may present with marked fever, fatigue, dizziness, muscle aches, loss of strength, and exhaustion. Patients often progress to signs of bleeding under the skin, in internal organs, or from body orifices, including the mouth, eyes, or ears―though patients rarely die from blood loss. Severely ill patients may pass progressively into shock, nervous system malfunction, coma, delirium, seizures, and death. Viral hemorrhagic fever infections in humans originally occur by accidental contact with an infected host animal. Subsequent human-to-human transfer of hemorrhagic viruses can occur and cause human epidemics. Well-publicized hemorrhagic viruses include the Marburg virus, Ebola virus, and Lassa fever virus.
Marburg hemorrhagic fever. Marburg virus disease presents as an acute febrile illness and can progress within 6 to 8 days to severe hemorrhagic manifestations. After an incubation period of 5 to 10 days, onset of the disease is sudden and is marked by fever, chills, headache, and myalgia. On approximately the fifth day after onset of symptoms, a maculopapular rash may appear, after which nausea, vomiting, chest pain, sore throat, abdominal pain, and diarrhea may occur. Signs and symptoms become increasingly severe and can include jaundice, inflammation of the pancreas, severe weight loss, delirium, shock, liver failure, massive hemorrhaging, and multi-organ dysfunction.
Fatality rates from previous outbreaks of Marburg virus infection have ranged from approximately 25% to approximately 80%. Mortality has been higher in outbreaks in which effective case management has been lacking. No vaccine or curative treatment is available, so only supportive treatment can be used. The virus can be spread to humans through direct contact with body fluids (e.g., blood, saliva, and urine) of an infected person or animal. The virus has been reported to survive for as long as several days on contaminated surfaces.
Marburg hemorrhagic fever was first identified in 1967 during simultaneous outbreaks affecting laboratory workers in Marburg and Frankford, Germany and in Belgrade, Yugoslavia. These outbreaks, which involved 31 cases and seven deaths, subsequently were linked to contact with infected monkeys imported from Uganda. Reports of Marburg virus disease are rare, and subsequent outbreaks have been limited to countries in sub-Saharan Africa. The environmental reservoir of the virus is unknown. The current outbreak in Angola is the first report of Marburg virus disease since 1998-2000, when the largest previously known outbreak occurred in the Democratic Republic of Congo, resulting in 149 cases and 123 deaths (case-fatality rate of 83%).
Angolan Outbreak. On March 23, 2005, the World Health Organization (WHO) confirmed that Marburg virus was the causative agent of an outbreak of viral hemorrhagic fever in Uige Province of northern Angola. During the period of October 1, 2004 to March 29, 2005, a total of 124 cases were identified. Of these, 117 had died (case-fatality rate of 94%), making this the largest and most lethal of Marburg virus outbreaks ever recorded. Approximately 75% of the reported cases had occurred in children aged less then 5 years. Adult cases had included health care workers. Predominant symptoms included fever, hemorrhage, vomiting, cough, diarrhea, and jaundice. The number of cases had begun increasing in February and then, more dramatically, in March. By April 27, 2005, the case total had risen to 275 and the death toll to 246 (case-fatality ratio of 93%).
WHO and international partners in the Global Outbreak Alert and Response Network (GOARN) are working with the Ministry of Health in Angola in conducting an investigation and in mounting a public health response. Outbreak-control efforts are directed at providing technical support for case management, strengthening infection control in hospitals, improving surveillance and contact tracing, and educating local residents about the disease and its modes of transmission. Two contributing factors make early detection of Marburg hemorrhagic fever difficult: the rarity of this disease and its similarity to other diseases seen in countries where deaths from infectious diseases are common. Neither the source nor the date of the initial cases in Angola can be identified with certainty.
Fortunately, the spread of disease beyond Uige Province has been limited. Of the 266 cases and 244 fatalities reported by April 20, fully197 cases and 183 deaths occurred in Uige municipality. Other municipalities in Uige Province account for an additional 56 cases and 50 deaths. WHO believes that the risk of international spread is low. No foreign nationals, with the exception of individuals involved in direct patient care, have become infected. There is no evidence that infected persons can spread the virus before they become ill. Shortly after symptom onset, patients become rapidly incapacitated and immobilized.
In theory, the measures needed to end the Angolan outbreak are few and straight forward: rapid detection and isolation of patients, tracing and management of close contacts, infection control in hospitals, and the wearing of protective clothing by staff. But these measures are complicated by the distinct features of this disease. The sudden onset, dramatic symptoms, rapid deterioration of patients, and absence of a vaccine or effective treatment invariably incite great anxiety in the affected populations. This anxiety, in turn, can interfere with control operations, when communities begin hiding cases and bodies because of suspicions about the safety of hospitals. For the affected communities, staff from the mobile response teams, fully suited in protective gear, are seen as taking away relatives and loved ones who many never be seen alive again.
Conditions in Angola―a country weakened by almost three decades of civil unrest―have presented additional challenges. Water and electricity are available intermittently. Weakened infrastructures, including those for communications and transportation, present other problems. Nevertheless, tools and methods developed during international responses to outbreaks of other diseases have been brought to bear on this outbreak. Important needs, which have ranged from satellite telephones and hand-held radio sets, to vehicles, protective equipment, disinfectants, and specialized staff, have been made available rapidly. An important goal is the transfer of skills and responsibilities for outbreak response to Angolan staff, and training efforts are under way with this goal in mind. WHO and its partners are prepared to continue their intervention efforts until the outbreak is brought under control.
References:
Brief report: outbreak of Marburg virus hemorrhagic fever – Angola, October 1, 2004 – March 29, 2005. MMWR Dispatch, March 30, 2005/54(Dispatch);1-2. Div of viral and rickettsial diseases, div of healthcare quality promotion, div of global migration and quarantine, national center for infectious diseases, CDC. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm564de330al.htm. (Accessed April 30, 2005.)
Marburg haemorrhagic fever in Angola – an update 15. Communicable disease surveillance & Response (CSR). World Health Organization. 22 April 2005. http://www.who.int/csr/don/2005_04_22/en/index.html. (Accessed April 30, 2005.
Marburg hemorrhagic fever – Angola (36). A ProMED-mail post. PRO/AH/EDR> Marburg hemorrhagic fever – Angola (36). International Society for Infectious Diseases. The Star online (Malaysia), Associated Press report, Sat 30 Apr 2005. http://www.thestar.com.my/news/story.asp?file=/2005/4/30/latest/20050430204353&sec=Latest. (Accessed April 30, 2005.)
What are viral hemorrhagic fevers? Viral hemorrhagic fevers, special pathogens branch, national center for infectious diseases, CDC. http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/vhf.htm. (Accessed April 30, 2005.)
Lynn M. Little retains the copyright of this column. No portion of this article may be republished without his express written permission.