Lassa fever

Context:

Recently, three persons diagnosed with Lassa fever in the UK died. The cases have been linked to travel to west African countries.

About Lassa fever

• Lassa fever, also known as Lassa hemorrhagic fever (LHF), is a type of viral hemorrhagic fever caused by the Lassa virus.
• The Lassa virus is a member of the Arenaviridae family of viruses.
• Descriptions of the disease date from the 1950s. 
• The virus was first described in 1969 from a case in the town of Lassa, in Borno State, Nigeria.
• Lassa fever is relatively common in West Africa including the countries of Nigeria, Liberia, Sierra Leone, Guinea, and Ghana.
• There are about 300,000 to 500,000 cases which result in 5,000 deaths a year
• Many of those infected by the virus do not develop symptoms.
• When symptoms occur they typically include fever, weakness, headaches, vomiting, and muscle pains. 
• Less commonly there may be bleeding from the mouth or gastrointestinal tract.
• The risk of death once infected is about one percent and frequently occurs within two weeks of the onset of symptoms. Of those who survive, about a quarter have hearing loss, which improves within three months in about half of these cases.
• The disease is usually initially spread to people via contact with the urine or feces of an infected multimammate mouse. Spread can then occur via direct contact between people.
• Diagnosis based on symptoms is difficult.
• Confirmation is by laboratory testing to detect the virus’s RNA, antibodies for the virus, or the virus itself in cell culture.
• Other conditions that may present similarly include Ebola, malaria, typhoid fever, and yellow fever.
• There is no vaccine. Prevention requires isolating those who are infected and decreasing contact with the mice. Other efforts to control the spread of disease include having a cat to hunt vermin, and storing food in sealed containers.
• Treatment is directed at addressing dehydration and improving symptoms.
• The antiviral medication ribavirin has been recommended, but evidence to support its use is weak.

What difference would a public health emergency make?

 A recent, and good example, of the difference this can make, was the announcementof a public health emergency in 2014 to tackle the Ebola virus outbreak.

• The announcement led to an emergency mode being activated with the attendant political will and funding which ultimately stoppedthe spread of the disease within 93 days.
• This is why the Nigerian Academy of Science is calling for more action.
• In particular, it is recommending that an interdisciplinary committee be set up comprising medical and veterinary specialists, epidemiologists, social scientists, media practitioners, community representatives.
• This would be along the lines of an approach known as One Health.
• This is rooted in the understanding that human health is affected by interactions between people, the environment and animals.
• Equally important is the need for the government to enhance the capacity of the national laboratory network for reliable and efficient diagnosis of suspected cases.
• This is because only about 20% of suspected Lassa fever cases are usually diagnosed.

The government should also provide adequate funds for a sensitive disease surveillance and response system. This is a system that ensures disease outbreaks (not just Lassa fever) are quickly noticed, diagnosed, and appropriate responses or containment measures are started in the shortest possible time.

What is a virus?

Viruses are not plants, animals, or bacteria. They are generally placed in their own kingdom.

In the strictest sense, viruses should not even be considered organisms – because they are not free-living. Viruses cannot reproduce and carry on metabolic processes without a host cell.

A virus is an acellular organism which are 10 to 100 times smaller than bacteria, about 20-300 nm in size.

Viruses can infect a variety of living organisms, including bacteria, plants, and animals.

The infective, extracellular (outside the cell) form of a virus is called the virion.

Virus Definition

A virus is a small collection of genetic code (either DNA or RNA) surrounded by a protein coat.

They lack metabolic machinery of their own to generate energy or synthesize proteins. They can reproduce only within a living cell – hence they are obligate intracellular parasites. They take over the functions of the host cell hence causing infection.

Viruses are inactive outside the host (crystallized form) and active inside. This puts them in the unique criteria of living as well as the non-living entity or ‘not truly living’.

Source: Indian Express