I am sure some people have never heard of the deadly disease called Lassa fever, some might have even heard of it, but they still bother less seeing bucks and does and pups in a mischief of rats dashing in and out of their uncovered raw food containers and even from all the nooks and crannies of their homes.
But to the uninformed and the ill-informed, Lassa fever is an acute and sometimes severe viral illness capable of causing bleeding from the mouth or gastrointestinal tract.
It is usually acute lasting between one to four weeks in people infected but could be severe in 20 per cent of them.
Lassa fever was first identified in three missionary nurses that fell ill and died in 1969 in a town in present day Borno State of Nigeria called ‘Lassa,’ after caring for an infected pregnant woman. Hence, the appellation ‘Lassa fever.’ Though an inkling of its existence had been on since the 1950s.
Lassa fever is caused by Lassa virus, a single-strandedRNA hemorrhagic fever of the family Arenaviridae. It is transmitted by the multimammate rat called Mastomysnatalensis (M. natalensis), a common rodent in sub-Saharan Africa. Infected Mastomys rats excrete the virus in their feces and urines throughout their lifespan without themselves being ill.
The disease is endemic in West African but mostly in Nigeria, Ghana, Benin, Liberia, Sierra-Leone, Guinea, Mali and Togo.The number of people infected peaks between December and June each year. It can also be life-threatening. But only about 20% of cases ended being severe: this is when the virus affects the kidneys, liver, spleen and several other organs.
Man become commonly infected: after inhaling air contaminated with aerosols of excretions of the Mastomys rats; by consuming the virus in foodstuffs or water or items contaminated by their urines and feces; preparing or eating the rats as a delicacy commonly called “bush meat”; by infection of open wounds by the virus. Person-to-person infections and laboratory transmission are also possible, mostly in healthcare facilities with inadequate infection prevention and control measures.
After infection the disease incubates in the body for between 2-21 days. Symptoms are of gradual onset, firstly as fever, then general weakness and malaise. In a few days, these may be followed by headache, sore throat, nausea, vomiting, diarrhea, abdominal pain, chest pain and cough. About 80% of patients are symptomless.
People with severe forms of the illness may bleed from the mouth, nose, vagina or gastro-intestinal tract which may result in low blood pressure.
Their faces may be puffy and lungs filled with fluid. There may be protein in their urines. In later stages, shock may result and they may have seizures, tremor, dis-orientation and coma.
Since the symptoms of Lassa fever is diverse and wide-ranging, it is often difficult to clinically diagnose it, especially in its early stages, since it shares a lot of symptoms with other hemorrhagic fevers such as Ebola or Marburg hemorrhagic fevers and they have to be ruled out first before making a firm diagnosis of Lassa fever. Also malaria, shigellosis, yellow fever and typhoid fever have similar symptoms.
Lassa fever can be treated with IV Ribavarin, if started early enough. Also, fluid and electrolytes loss should be appropriately replaced, so also oxygenation and blood pressure support as needed. About a quarter of patients that recovered from Lassa fever would be deaf. Though, hearing is restored in about half of them after 1-3 months but only partially. They may also ephemerally lose body hairs and may have disturbed gaits but these would later be fully restored.
In fatal cases, death usually occurs within 14 days. Overall, only about 1% of infected people would eventually die, but up to15% of those severely infected would die.
The disease is severe in late stages of pregnancy when fetal loss and maternal death may occur in more than 80% of cases during the third trimester of pregnancies.
Generally, Lassa fever can be prevented by avoiding any contact with Mastomys rats. Food should be stored in rat-proof containers and rats presence in homes should never be condoned.
The habit of eating “bush meat” should be done away with. And as Don McPherson once advised: “True prevention is not waiting for bad things to happen, it’s preventing things from happening in the first place”.
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