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Marburg virus

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Marburg virus
Marburg virus
Marburg virus particles, approx. 100,000x magnification
Scientific classification
Domain:Virus
(unranked)(-)ssRNA viruses
Order:Mononegavirales
Family:Filoviridae
Genus:Marburgvirus
Species:Lake Victoria marburgvirus

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 percent.

As of May 2005, the virus is attracting widespread press attention for an outbreak in Angola. Beginning in October 2004 and continuing into 2005, the outbreak, which remains out of control, is the world's worst epidemic of any kind of hemorrhagic fever.

Contents

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 percent up to 100 percent. [1] (http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/marburg.htm) [2] (http://www.recombinomics.com/News/03270504/Marburg_Luanda_Transmission.html)

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] (http://www.swissinfo.org/sen/swissinfo.html?siteSect=143&sid=5687036&cKey=1113528035000)

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] (http://www.genphar.com/news/100702.html) 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] (http://www.canada.com/health/story.html?id=a4419199-0ee7-42ef-9779-2532c9608687)

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 May 16, 2005, Angola's health department reported that 292 of 336 known cases had been fatal. There have been cases in 7 of 18 provinces but the outbreak seems mostly confined to Uige province.

According to the World Health Organization, 80 percent of the deaths in the early stages of the Angola outbreak were children under the age of 15, but that has dropped to 30 to 40 percent. [6] (http://www.kentucky.com/mld/kentucky/news/world/11489787.htm) 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

Monthly Reported Deaths (http://www.reliefweb.int/rw/RWB.NSF/db900SID/DDAD-6B6KXM?OpenDocument)
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

Weekly Reported Deaths
WHO Report Date Cumulative Deaths Deaths During Prior Week
April 1,2005 (http://www.who.int/csr/don/2005_04_01/en/index.html) 132 n/a
April 8, 2005 (http://www.who.int/csr/don/2005_04_08a/en/index.html) 180 48
April 15, 2005 (http://www.who.int/csr/don/2005_04_15/en/index.html)* 207 27
April 22, 2005 (http://www.who.int/csr/don/2005_04_22/en/index.html) 244 37
April 29, 2005 (http://www.who.int/csr/don/2005_04_29/en/index.html) 255 11
May 6, 2005 (http://www.who.int/csr/don/2005_05_06/en/index.html) 277 22
May 11, 2005 (http://www.who.int/csr/don/2005_05_11/en/index.html)** 276 -1****
May 18, 2005 (http://www.who.int/csr/don/2005_05_18/en/index.html) 311 35
May 27, 2005 (http://www.who.int/csr/don/2005_05_27a/en/index.html)*** 335 24
June 7, 2005 (http://www.who.int/csr/don/2005_06_07/en/index.html)*** 357 22
June 17, 2005 (http://www.who.int/csr/don/2005_06_17/en/index.html)*** 356 -1****
  • *No WHO report was issued between the 15th and the 21st (http://www.who.int/csr/don/archive/disease/marburg_virus_disease/en/). This appears associated with the administrative reclassification of cases (http://www.who.int/csr/don/2005_04_15/en/index.html).
  • **Not an entire week. No WHO report for the 13th.
  • ***Over a week.
  • **** No explanation provided for the decrease in cumulative deaths.

Control efforts

Countries with direct airline links, such as Portugal, have begun screening passengers arriving from Angola. The Angolan government has 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 have also complained about a shortage of personal protection equipment such as gloves, gowns and masks. Mdecins Sans Frontires (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, a team of international experts has prepared a special isolation ward to handle cases from the countryside. The ward can accommodate up to 40 patients, but there has been growing 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] (http://www.iol.co.za/index.php?set_id=1&click_id=84&art_id=qw1113046741868B243) A specially-equipped isolation ward at the provincial hospital in Uige is reported to be empty, even though the facility is at the center of the outbreak. [8] (http://www.reuters.com/newsArticle.jhtml?type=healthNews&storyID=8193079) WHO has been forced to implement what they describe as a "harm reduction strategy" which entails 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.

See also

External links and references

de:Marburg-Fieber es:Virus de Marburgo fr:Fivre hmorragique de Marburg it:Marburg (virus) ja:マールブルグ熱 nl:Marburgvirus pt:Vrus de Marburg fi:Marburg (virus) zh:馬爾堡病毒

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