What we know about Lassa fever, the recently diagnosed viral hemorrhagic fever in three patients in the UK.
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In recent days the United Kingdom Health Safety Agency (UKHSA) announced the diagnosis of three cases of Lassa fever, one of which unfortunately proved fatal. The infections they concerned patients related to a recent trip to Africa occidentalewhere this illness it is endemic. The risk to public health is considered to be very low. According to data from the United States Centers for Disease Control and Prevention, it is estimated that the infection affects up to 300,000 people a year, causing about five thousand deaths. As specified by the National Institute of Health (ISS), Lassa Fever is part of the viral hemorrhagic fevers (Fev), among which there is also that caused by the notorious Ebola virus. These are “systemic pathologies of viral origin, characterized by sudden, acute onset and often accompanied by haemorrhagic manifestations”, writes the ISS. Lassa fever is named after a city in the Nigeria, where about half a century ago she was first diagnosed in two nurses. Here are what the symptoms are and how it is transmitted.
What are the symptoms of Lassa fever
Lassa fever, unlike other viral haemorrhagic fevers, has a gradual onset and incubation time can be up to 21 days, compared to an average of 1-9 days for the others, explains the ISS. Between symptoms initials are reported headache (headache); fever; muscle aches (myalgia); dry coughdifficulty in eating (dysphagia), chest pain, even severe, pharyngodynia with tonsillar exudate and a number of gastrointestinal conditions such as nausea, He retched e diarrhea. These are generic symptoms that in large part can be associated with multiple diseases, including severe flu and COVID-19, the infection caused by the SARS-CoV-2 coronavirus. With the emergence of complications the clinical picture becomes more specific; as indicated by the ISS, in fact, “edema of the face and neck, breathing difficulties, pleural and pericardial effusion, proteinuria (high concentration of protein in urine NDR), encephalopathy, mucosal bleeding”, Such as from the nose or gums. They can also manifest themselves hypotension e shock. They are also mentioned in the MSD Manuals for healthcare professionals dizziness, tinnitus e hearing loss, which can become permanent in patients with more severe infection. Lassa fever can be mild or even asymptomatic in the80 percent of the infected, while the remaining 20 percent develop one severe multisystem disease. The ISS specifies that the mortality rate general is just 1 percent, but goes up to 20 percent for untreated cases. Mortality is much higher for women who are pregnant or have just given birth, ranging from 50 to 92 percent. Patient recovery or death occurs between 7 and 31 days.
How Lassa fever is transmitted
Lassa Fever is caused by a arenavirus – the Lassa virus (Lassa mammarenavirus) – which is transmitted to humans by contact with feces, urine, saliva and other excreted rodents. The main animal reservoirs are the pygmy mouse Mus baoulei, i rats of the genus Mastomys (M. natalensis and M. erythroleucus) and Hylomyscus pamfi. They are all animals that can be found in the homes of African countries most affected by the epidemics, including Sierra Leone, Guinea, Nigeria, Togo, Liberia and Ghana. Transmission can also take place between man and mancoming into contact with i body fluids of an infected person. “In some cases, after accidental transmission, human-to-human transmission can occur through direct contact with blood, tissues, secretions or excretions of infected people, especially in the family and nosocomial environment,” specifies the ISS. MSD manuals indicate that human to human infection is common in the hospital in the absence of personal protective equipment (PPE), such as face masks, face shields, goggles, and gloves, which we learned about well during the COVID-19 pandemic.
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How is Lassa fever treated?
The treatment of choice against Lassa fever is based onantiviral ribavirin, which is capable of reducing mortality if started early in the infection. Lethality can be reduced tenfold if the administration begins within the sixth day from the infection, indicate the MSD Manuals. Treatment involves an initial dose of 30 mg / kg IV (up to 2 grams) “followed by 16 mg / kg IV (maximum 1 g / dose) every 6 hours for 4 days, then 8 mg / kg IV (maximum 500 mg / dose) every 8 hours for 6 days ”, specify the MSD Manuals. As with other hemorrhagic fevers, supportive therapy is required to maintain the volume (total blood volume) andhydroelectric balance. “To control bleeding, plasma, platelets, blood can be administered,” specifies the ISS, adding that antibiotics they can be useful in preventing secondary infections. To date there is no vaccine against Lassa fever.