Marburg virus

 

Marburg virus

“Marburg virus including origins of the virus past outbreaks transmission sign and symptoms  and critical complications that can lead to death from this infection.”

 

Etiology of Murburg virus?

 So the Marburg virus is a virus of the family filoviridae so if we were to break down the word filoviridae the prefix stands for thread-like appearance and that really denotes the thread-like appearance of  the virus itself. it is the same family of viruses as the Ebola virus and it is a negative sense single stranded RNA  virus again very key terms here negative sense its single stranded and its an RNA  virus there are actually 2 variants of the marburg  virus one of them is known as lake Victoria Marburg virus in the second one is Ravin Marburg virus. however both of them have similar clinical presentations so we just discuss them as if they are the same virus now the virus was 1st identified in an It's outbreak that occurred 1967 in Germany in Yugoslavia and here is a map of Germany here and Yugoslavia would have been a country in this area of Europe and what is believed to have happened is that there was a species to species transmission of the Marburg virus from Vervet monkeys to humans so what had happened was vervet monkeys were brought from Uganda it had the virus and they had transmitted to humans in Europe and this was the first outbreak and during this first outbreak the mortality rate was very high it was 25 to 25% mortality rate so a quarter of individuals who became infected died from this infection. In since then there have been several other outbreaks of Marburg virus so the previous outbreaks include the one we just talked about but more recent one include a outbreak from 1998-2000 in the democratic Republic of Congo.

So here is a map of the democratic Republic of Congo here what is believed to have happened is that men working in an abandoned mine in the DRC or exposed to bats and these bats also carried the Marburg virus this outbreak was extremely deadly the mortality rate here was 80 to 90% so 8 to 9 out of 10 people who were infected with his virus died from the infection. Another outbreak that occurred was in Angola in 2004 so Angola is Next to the DRC or democratic Republic of Congo is just Southwest of it and this is actually the largest outbreak of Marburg virus on record at the time of recording this lesson there were 400 cases of the virus at this outbreak and what had happened was there was a hospital a pediatric board more specifically so there is a floor of pediatric patients and there was spread of the virus in this pediatric floor through contaminated transfusion equipment again the mortality right here was very high 80 to 90%. Now there's been some recent infections since then but not to the extent of the Angola outbreak and most of it has been from tourists being exposed to bats in caves in Uganda.

 

 How marburg virus is the virus transmitted?

The viral reservoir for the Marburg virus our fruit bats of the species “ROUSETTUS aegyptiacus” so here's an image of the fruit bat now what is found is that the fruit bats excrete the virus in bodily fluids so we talked about this before tourists going into caves in certain areas where these fruit bats reside can be exposed to some of these bodily fluids and that's exactly how this virus can be transmitted from a bat to a human so the Marburg virus can be transmitted from a bat to a human so the human gets exposed to bats and bat fluids they become infected and then once the person is infected they can spread it to other people through horizontal transmission.

 

 So this also is through shedding of the virus in bodily fluids and we've seen this and passed outbreaks through transfusion equipment if there's any contaminated blood that is being given to other people contaminated blood products can contaminate and infect other people so person to person transmission is possible through exposure to infected bodily fluids so that's what seems to happen when a person gets infected they can transmit it to other people through bodily fluids like blood but when a person gets initially infected if they're exposed to bodily fluids from a bat it can be in droplets and the droplets can enter to an individual's mucosal membranes like the eyes the nose and in the mouth.

 

Marburg virus transmitted sexually?

The virus can remain in certain body fluids (including semen) of a patient who has recovered from MVD, even if they no longer have symptoms of severe illness. There is no evidence that Marburg virus can spread through sex or other contact with vaginal fluids from a woman who has had MVD.

 

Marburg virus affect pregnancy?

Women who are pregnant and infected with either Marburg viruses can be especially infectious. The placenta has a high viral load, and maternal blood, vaginal secretions, amniotic fluid, urine, sweat, saliva, feces, vomit, and breast milk are all potential sources of virus.

 

What is the pathogenesis of the marburg virus infection?

what happens is when an individual does become infected with the Marburg virus through their mucosa like the jump type of their eyes or nasal mucosa and their oral mucosa their oral mucosa if virus enters and infects macrophages and dendritic cells so the virus gets picked up usually through phagocytosis and it's into the cell entering the cell in an end zone the virus then can unravel and disassemble leaving its viral RNA and then viral RNA will replicate inside the cell that viral RNA can then assemble inside the cell in the endoplasmic reticulum and then that virus is assembled like it's package in the Golgi apparatus and the virus can then mature and then be released from that infected cell so that it can infect other cells in the body that's how it enters and replicates and releases to infect other cells after that the virus can then disseminate through the lymphatic system so can enter the lymph nodes in the lymphatics to spread throughout the body.

 Now there are several different mechanisms by which the Marburg virus can cause illness and infection we talk about one of them it can infect the macrophages and dendritic cells in particular the macrophages when they become infected they can increase the production of chemokines  leads to a variety of signs and symptoms. Another thing you can do is it can lead to damage to visceral organs like the liver in the spleen in the Marburg virus can also lead to an upregulation of tissue factor and tissue factor is the beginning of the extrinsic pathway in coagulation cascade it can lead to a coagulopathy and making more more fibrin clot in area where they don't need them will deplete clotting factors.

So disseminated intravascular coagulation or DIC is a process where fibrin clots are made where they do not need to be made and there's an increase in fibrin clot formation leading to depletion of clotting factors and when we deplete the clotting factors we won't be able to make clots where we need to make them and this is exactly what happens in DIC there's clots where there don't need to be and then there's no clots where there should be so we get bleeding issues and that's exactly what happens in Marburg virus infections.

 

 What are the clinical features of the Marburg virus?

 First the virus has to incubate so when it infects an individual the incubation period is approximately one week after that 1 week there is an abrupt onset of symptoms these include fever and chills malaise and weakness very tired very weak. Nausea vomiting and diarrhea are very common as well including anorexia so they have a very low appetite and they have a very severe headache and bad myalgias or bad muscle pain particularly of the trunk and the lower back and what is key to the morbidity of Marburg virus infection is its bleeding and we talked about the disseminated intravascular coagulation leads to the depletion of clotting factors and we get excessive bleeding where we don’t have clotting factors and this is the exactly what happens this appears to occur later on an infection so early on in affection we don’t have this bleeding risk but later on an infection we do  and this is where we begin to see issue like new coastal bleeding so we can see bleeding of gums we can also see petechiae palpable purpura we can also see gastrointestinal bleeding like hematochezia in Molina this is how the Marburg virus infection can be so deadly because of excessive losses of blood other clinical findings with regards to Marburg virus infection include a diffuse maculopapular rash very common in many viral infections.

 we can also see chest pain and shortness of breath with this infection and we can see Hiccups this is very unusual finding but with regards to a Marburg virus infection we can see a patient having issue with excessive hiccupping and three big ones that can also occur that are also tied with that morbidity mortality of the Marburg virus infection our confusion seizures and Coma. now there are particular laboratory investigations you might see with the Marburg virus infection these include “transaminitis” the transaminitis is essentially elevated transaminases is from the liver so increased ALT and AST because we talked about this before the virus can infect can damage the liver we can also see leukopenia so” low levels of white blood cells” thrombocytopenia” low levels of platelets” and disseminated intravascular coagulation so the DIC and the thrombocytopenia are tied together platelet's get destroyed by the DIC process and the DIC will lead to increases in PT PTT  and INR and you'll see decreased fibrinogen but an elevated D dimer so these are all findings you might see with DIC.

 

 How do we make the diagnosis of Marburg virus infections?

 The diagnosis of Marburg virus can occur through two mechanisms one is my reverse transcription polymerase chain reaction for detection of viral genetics that's one way you can do it the other one is Eliza for detection of viral antigens.

 Eliza is enzyme linked immunosorbent assay the treatment of Marburg virus infections is a supportive one this is a virus there are no official antiviral treatments for the Marburg virus its a supportive treatment where we essentially treat symptoms and lot of times we're gonna want to try to treat your bleeding risk so blood transfusions and give them platelets give them whatever they need with regards to their disseminated intravascular coagulation.

 

How do we treat Marburg virus infections?

No cure or effective treatment exists for Marburg virus disease, making preventing the disease critical through steps like personal protective equipment and safe handling of body fluids.

There is question of using Favipiravir  as a possible treatment for Marburg virus, this is in early stages of research at this point so right now this is a possible way to treat this infection but we still have limited data so most of the time it's supportive treatment and there is no vaccine for Marburg virus infection.