Written By : Brian Igboin

Lassa fever intervention

April 25 / 2018

Lassa fever is an acute Viral Hemorrhagic associated with persistent high fever. Over the decade, clinical cases of the disease had been known but haven’t been traced to a viral pathogen. The term Lassa was coined out from a town in Borno State of Nigeria where the disease was first described in 1969. However, it can be found in other places, especially in West Africa e.g. Liberia, Guinea and Sierra Leone where the infection is endemic. The multimammate mouse (Mastomys natalensis) member of the family Arenaviridae is the primary host of the Lassa Virus. These commensal rodents are found in houses during the dry season and the surrounding fields in the rainy seasons. Communities where Lassa Virus rats have been trapped are located in rain forest (Ref) and 300,000–500,000 cases of outbreak are recorded annually with death rate of approximately 5,000. MODE OF TRANSMISSION Research has it that rainfall seems to be an important ecological factor because a recent longitudinal study in rodents demonstrated that Lassa virus infection was two to three times higher in rainy season than in the dry season. No recent studies has indicated that the virus can survive better in humid than in dry soil, but evidence points in this direction. Lassa Virus can be transmitted by contact with faeces or urine of animals accessing grain stores in residences, e.g. (Grains spread out to dry along the roads by farmers). People become infected consume infected bush rat or food contaminated with the rat excreta, urine deposited on surfaces such as floors, beds, household utensils or in food and water. Transmission also occurs from human to human through contact with fluid and aerosol secretions in the form of sneezing, sputum, seminal fluid, stool, direct contact or inhalation of infected body fluids such as blood, urine, saliva, throat secretion. Infection in humans occurs via animal excrement exposure through the respiratory or gastrointestinal tracts. Inhalation of tiny particles of infective material (aerosol) is believed to be the most significant means of exposure. It is possible to acquire the infection through broken skin or mucous membranes that are directly exposed to infective material. Person to person transmission has also been established, presenting a disease risk for healthcare workers. Transmission via sexual contact transmission has not been established. The illness usually starts with fever, general weakness and malaise. Other signs and symptoms are headache, sore throat, pain behind the breast bone, nausea, vomiting, diarrhea, cough, abdominal pain and red spots. In severe cases, it may progress to swollen face, bleeding (from mouth, nose, and vagina), gastrointestinal tract and low blood pressure. Almost every tissues of the body are infected. It starts with the mucosa, intestine, lungs and urinary system, and then progresses to the vascular system. Men and women from all age group are infected. Populace at greater risk are those in areas of poor sanitation and lack of public health workers managing such cases. After six to twenty-one days of incubation period, an acute illness with multi organ involvement develops. There are Non-specific symptoms which includes fever, and muscle fatigue, as well as conjunctivitis, mucosal bleeding and facial swelling. The other symptoms arising from the affected organs include Gastrointestinal tract Nausea, Vomiting with blood in it, Diarrhea, Constipation, swallowing difficulty, hepatitis, stomach ache, chest pain, abnormal high heart rate(tachycardia) Diagnosis of Lassa virus can be: 1. Immunoglobulin presence demonstration 2. Virus isolation from blood, throat washing and urine. During the febrile phase of the disease, isolation of blood or serum should be up to 2 weeks. Antibody can be detected by CF, IFA, or ELISA. When a case is severe, patients can die before the antibodies appear. In some laboratory results: • There is either a low, normal or moderately elevated Leukocyte count • Platelet counts are usually normal, but might be slightly low. • AST (SGOT) and ALT (SGPT) are usually elevated (10x normal). • Chest x-rays are normal, but pleural effusions or basilar pneumonitis may be seen • Albuminaturia (excessive amounts of albumin proteins in the urine) is common. • Abnormal ECGs Prevention Intensive education will bring the risk of the Lassa virus to its minimum. The control of the Mastomys rodents is impractical, so keeping a clean environment will help keep rodent away from homes as well as effecting good personal hygiene, the use of masks, gloves, safety glasses and laboratory coats are advised when dealing with infected person, Cover all foods and water properly, Cook all foods thoroughly, Block all rat hideouts and places where rat can gain entrance, proper fumigation, avoid spreading food where rats can have access to it, proper garbage disposal from homes, keeping cats. Public awareness programme of the mode of contact of Lassa fever using electronic media or printed flyers and banners emphasizing on the high case fatality rate, people affected should be urgently taking to a special center for disability prevention or limitation, The disease is clear in 80% cases and a difficult course in the remaining 20%. The virus is responsible for 5,000 deaths annually (estimated value). Elimination of Mastomys is not possible because they are abundant in endemic areas. As soon as Lassa fever is suspected, or persistent fever is not responding to the standard treatment for malaria and typhoid, report to the nearest health centre. Treatment: Early treatment with Oral Ribavirin is recommended. In severe infection, injection of Ribavirin is used. Barrier nursing is highly recommended, isolation facilities should be made available for persons suspected of Lassa fever infection and proper disposal of their body fluid and excreta. \\ REFERENCES Adewuyi ,G.M., Fowotade, A. and Adewuyi,B.T., 2009. Lassa Fever: Another infectious menace: AFR.J.CLN.EXPER.MICROBIOL, 10(6),p.144-155. Ute, I., Okosun, J. and Inebenebor, J., 2009. Prevention of Lassa fever in Nigeria Transactions of the Royal Society of Tropical Medicine and Hygiene, [online] Available at: [Accessed 21february 2012]. Jones K, et al., 2008. Global trends in emerging infectious diseases. 451(7181):990–993. Fichet-Calvet, E., and Rogers D. J., 2009. Risk Maps of Lassa Fever in West Africa: PLoS Neglected Tropical Disease, [online] Available at< HYPERLINK \"http://www.plosntds.org\" http://www.plosntds.org> [ Accessed 28 February 2012]. Daniel G. et al., 2010. Clinical infectious diseases review of the literature and proposed guidelines for the use of oral ribavirin as post exposure prophylaxis for Lassa fever Sheik H. et al.,2008. New opportunities for field research on the pathogenesis and treatment of Lassa fever: Science Direct, available online at< Http: HYPERLINK \"http://www.sciencedirect.com\" www.sciencedirect.com [Accessed 28 February 2012]

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