Template:Taxobox begin Template:Taxobox image Template:Taxobox begin placement virus Template:Taxobox group v entry Template:Taxobox ordo entry Template:Taxobox familia entry Template:Taxobox genus entry Template:Taxobox species entry Template:Taxobox end placement Template:Taxobox end The Marburg virus is the causative agent of Marburg hemorrhagic fever. Both the disease and virus are related to Ebola and originate in the same part of Africa (Uganda and Eastern Congo). The zoonosis is of unknown origin, but some scientists believe it may be hosted by bats.
The disease is spread through bodily fluids, including blood, excrement, saliva, and vomit. There is no cure or vaccine for this deadly and infectious virus. Victims suffer a high fever, diarrhea, vomiting, and severe bleeding from bodily orifices and usually die within a week. Fatality rates range from 25 to 100 %.
In the spring of 2005, the virus attracted widespread press attention for an outbreak in Angola. Beginning in October 2004 and continuing into 2005, the outbreak, which is now thought to be under control, was the world's worst epidemic of any kind of hemorrhagic fever.
The Marburg virus
The viral structure is typical of filoviruses, with long threadlike particles which have a consistent diameter but vary greatly in length from an average of 800 nanometres up to 14,000 nm, with peak infectious activity at about 790 nm. Virions (viral particles) contain seven known structural proteins. While nearly identical to Ebola virus in structure, Marburg virus is antigenically distinct from Ebola virus — in other words, it triggers different antibodies in infected organisms. It was the first filovirus to be identified.
Infection details
Because many of the signs and symptoms of Marburg hemorrhagic fever are similar to those of other infectious diseases, such as malaria or typhoid, diagnosis of the disease can be difficult, especially if only a single case is involved.
The disease is characterised by the sudden onset of fever, headache, and muscle pain after an incubation period of 3-9 days. Within a week, a maculopapular rash develops, followed by vomiting, chest and abdominal pain, and diarrhea. The disease can then become increasingly damaging, causing jaundice, delirium, organ failure, and extensive hemorrhage. Patients generally die from hypovolemic shock as fluid leaks out of the blood vessels, causing blood pressure to drop.
Recovery from the disease is prolonged and can be marked by orchitis, recurrent hepatitis, transverse myelitis or uveitis, or inflammation of the spinal cord, eyes, or parotid gland. Depending upon health care and hospitalization support, the disease can have very high fatality rates, with estimates ranging from 25 % up to 100 %. [1] [2]
Infection is believed to be spread by close contact with body fluids of those infected, and the virus is unlikely to spread through casual contact. Patients are most contagious during the acute phase of the illness when fluids such as vomit and blood are present. Unsafe burial practices such as embracing, kissing or ritual bathing of the corpse present another infection vector. [3]
According to a report in the New York Times, the virus moves very quickly. "On Day 3 of the infection, fewer than 200 viruses are in a drop of blood. By Day 8, there are five million."
Treatment and prevention
As with other hemorrhagic fever viruses, the treatment options for Marburg are limited. Hypotension and shock may require early administration of vasopressors and hemodynamic monitoring with attention to fluid and electrolyte balance, circulatory volume, and blood pressure. Viral hemorrhagic fever (VHF) patients tend to respond poorly to fluid infusions and rapidly develop pulmonary edema.
Patient caregivers require barrier infection control measures including double gloves, impermeable gowns, face shields, eye protection, and leg and shoe coverings.
A few research groups are working on drugs and vaccines to fight the virus. In 2002, Genphar, a company doing research for the United States Army's biodefense program, announced that an experimental vaccine protected animals from a high dose of Marburg virus. The tests were conducted by the United States Army Medical Research Institute of Infectious Diseases (USAMRIID). According to the company, all animals in the control group died within days whereas all animals that received the regular dosage of the vaccine were fully protected. The company has moved on to non-human primate trials. [4] Late in 2003, the US government awarded the company a contract worth $8.4 million for what was described as "a multivalent Ebola, Marburg filovirus vaccine program".
In June 2005 scientists at Canada's National Microbiology Laboratory announced that they had also developed vaccines for both Marburg and Ebola that showed significant promise in primate testing. Studies on mice also suggested that the vaccine might be an effective treatment for the disease if it is administered shortly after a patient is infected. To make the vaccines the scientists fused a surface protein from the viruses they hope to protect against onto an animal virus - vesicular stomatitis - which is thought to be of no threat to humans. [5]
Early outbreaks
This virus was first documented in 1967, when 31 people became ill in the German town of Marburg, after which it is named, as well as in Frankfurt am Main and the then Yugoslavian city of Belgrade. The outbreak involved 25 primary infections, with 7 deaths, and 6 secondary cases, with no deaths. The primary infections were in laboratory staff exposed to the Marburg virus while working with monkeys or their tissues. The secondary cases involved two doctors, a nurse, a post-mortem attendant, and the wife of a veterinarian. All secondary cases had direct contact, usually involving blood, with a primary case. Both doctors became infected through accidental skin pricks when drawing blood from patients.
The outbreak was traced to infected African grivets of the species Cercopithecus aethiops taken from Uganda and used in developing polio vaccines. The monkeys were imported by Behringwerke, a Marburg company founded by the first winner of the Nobel Prize in Medicine, Emil von Behring. The company, which at the time was owned by Hoechst and is now part of Aventis, was originally set up to develop serums against tetanus and diphtheria.
In 1975, three people in South Africa were infected by the Marburg virus by a man returning from Zimbabwe, resulting in one death. Two similar cases in 1980 and 1987 occurred in Kenya after European visitors went to Kitum Cave. Both later died. The next major outbreak occurred in the Democratic Republic of Congo from 1998 to 2000, where 123 of 149 cases were fatal. This outbreak originated with miners in Durba and Watsa in Orientale, Congo.
2004-2005 outbreak in Angola
In early 2005, the World Health Organization began investigating an outbreak of a then-undiagnosed hemorrhagic fever in Angola, which was centered around the northeastern Uige Province. The disease may have surfaced as early as March 2004 in a crowded children's ward. A doctor noted that a child, who subsequently died, was displaying signs of hemorrhagic fever. By October, the death rate on the ward went from three to five children a week to three to five a day. On March 22, 2005, as the death toll neared 100, the cause of the illness was identified as the Marburg virus. By July, 2005, Angola's health department reported more than 300 cases were fatal. There were cases in 7 of 18 provinces but the outbreak was mostly confined to Uige province.
According to the World Health Organization, 80 % of the deaths in the early stages of the Angola outbreak were children under the age of 15, but that dropped to 30 to 40 % in later stages. [6] The virus has also taken a toll on health care workers, including 14 nurses and two doctors.
There has been speculation that the high death rate among children in the early stages of this outbreak may simply be due to the initial appearance of the disease in the children's ward at the Uige hospital. Early death rates (prior to effective monitoring) are meaningless as only the dead are adequately counted.
Deaths by Month
| Month Year | Deaths Reported During Month |
|---|---|
| October 2004 | 3 |
| November 2004 | 4 |
| December 2004 | 7 |
| January 2005 | 20 |
| February 2005 | 30 |
| March 2005 | 47 |
| April* 2005 | 123 |
| May** 2005 | 80 |
- *This represents the difference between WHO reports of April 1 and April 29.
- **This represents the difference between WHO reports of April 29 and May 27.
Deaths by Week
| WHO Report Date | Cumulative Deaths | Deaths During Prior Week |
|---|---|---|
| April 1,2005 | 132 | n/a |
| April 8, 2005 | 180 | 48 |
| April 15, 2005* | 207 | 27 |
| April 22, 2005 | 244 | 37 |
| April 29, 2005 | 255 | 11 |
| May 6, 2005 | 277 | 22 |
| May 11, 2005** | 276 | -1**** |
| May 18, 2005 | 311 | 35 |
| May 27, 2005*** | 335 | 24 |
| June 7, 2005*** | 357 | 22 |
| June 17, 2005*** | 356 | -1**** |
| July 13, 2005 | 312 | ***** |
- *No WHO report was issued between the 15th and the 21st. This appears associated with the administrative reclassification of cases.
- **Not an entire week. No WHO report for the 13th.
- ***Over a week.
- **** No explanation provided for the decrease in cumulative deaths.
- ***** Report states that a review of data has led to an downward estimation in total deaths.
Control efforts
Countries with direct airline links, such as Portugal, screened passengers arriving from Angola. The Angolan government asked for international assistance, pointing out that there are only about 1,200 doctors in the entire country, with some provinces having as few as two. Health care workers also complained about a shortage of personal protection equipment such as gloves, gowns and masks. Médecins Sans Frontières (MSF) reported that when their team arrived at the provincial hospital at the centre of the outbreak, they found it operating without water and electricity. Contact tracing is complicated by the fact that the country's roads and other infrastructure have been devastated after nearly three decades of civil war and the countryside remains littered with land mines.
One innovation in the Angola outbreak has been the use of a portable laboratory operated by a team of Canadian doctors and technicians. The lab, which can operate on a car battery, has eliminated the need to send blood samples outside the country for testing. This has reduced the turnaround time from days or weeks to about four hours.
Meanwhile, at Americo Boa Vida Hospital in the capital, Luanda, an international team prepared a special isolation ward to handle cases from the countryside. The ward was able to accommodate up to 40 patients, but there was some resistance to medical treatment. Because the disease has almost invariably resulted in death, some people have come to view hospitals and medical workers with suspicion and there was a brief period when medical teams were attacked in the countryside. [7] A specially-equipped isolation ward at the provincial hospital in Uige was reported to be empty during much of the epidemic, even though the facility was at the center of the outbreak. [8] WHO was forced to implement what they described as a "harm reduction strategy" which entailed distributing disinfectants to affected families who refuse hospital care. An education effort and an increase in the number of Angolan health practitioners in the outbreak area, has resulted in improved relations with the community.
Fiction
In the TV series Millennium, a modified version of the Marburg virus breaks out in Seattle, killing (amongst others) Frank Black's wife, Catherine.
In the TV series Medical Investigation episode 17 the Marburg virus breaks out in New York killing 5 from a total of 6 infected persons.
Further reading
- Ebola
- Biohazard, a book by Ken Alibek
- The Hot Zone, a book by Richard Preston ISBN 0517171589
- The Coming Plague, a book by Laurie Garrett ISBN 0374126461
- Plagues and Peoples, a book by William McNeill ISBN 0844664928
- Lassa fever