Resurgence Of Lassa Fever In Nigeria

By Livy-Elcon Emereonye

Sometimes ago, I received a call from some media con­sultants that they would like to come and interview me on Lassa fever. And my reaction was wow, Lassa fever again! Why Lassa fever? There is a possible re­surgence of the fever in Nigeria. We even play “politics” with our lives. Lassa fever had been with us so if there is resurgence now, we have ourselves to blame. This is because, more than anything, Lassa fever is primarily a disease of hygiene. How clean is our en­vironment? What is our person­al hygiene? What do we feed on? What type of health policies do we have, and how functional are they? Our problem is Nigeria is more of a problem of implemen­tation.

 Lassa fever is caused by a sin­gle-stranded RNA virus that is animal borne (zoonotic). It can cause a potentially fatal illness that can rapidly spread. The vi­rus is spread by a particular type of rat known as the ‘multimam­mate rat’(Mastomys natalen­sis) that lives in large numbers in west, central, and east Africa. 

While we are what we eat, our living conditions have direct im­pact on our health. People can get Lassa fever, also known as Lassa haemorrhagic fever (LHF) through contact with the urine or droppings of an infected rat; catching and preparing infected rats as food; inhaling tiny parti­cles in the air contaminated with infected rat urine or droppings; and rarely, direct contact with a sick person’s blood or body flu­ids, through mucous membranes, like eyes, nose, or mouth. How­ever, It should be noted that peo­ple with Lassa fever are not be­lieved to be contagious before they have symptoms. Lassa fever is not spread through casual con­tact (like hugging, shaking hands, or sitting near someone). 

Once infected, “multimam­mate rat” (Mastomys natalen­sis), the reservoir or host of Las­sa virus, is able to excrete virus in urine for an extended time period, maybe for the rest of its life. The rodents breed frequent­ly, produce large numbers of off­spring. Also they readily colonize human homes and areas where food is stored. According to Cen­tre for Disease Control and Pre­vention (CDC), “Transmission of Lassa virus to humans occurs most commonly through inges­tion or inhalation. Mastomys ro­dents shed the virus in urine and droppings and direct contact with these materials, through touching soiled objects, eating contami­nated food, or exposure to open cuts or sores, can lead to infec­tion. Because Mastomys rodents often live in and around homes and scavenge on leftover human food items or poorly stored food, direct contact transmission is common. Mastomys rodents are sometimes consumed as a food source and infection may occur when such infected rodents are caught and prepared.

Contact with the virus may also occur when a person inhales tiny par­ticles in the air contaminated with infected rodent excretions. This aerosol or airborne transmission may occur during cleaning activ­ities, such as sweeping.

Direct contact with infected ro­dents is not the only way in which people are infected; person-to-person transmission may oc­cur after exposure to virus in the blood, tissue, secretions, or excre­tions of a Lassa virus-infected in­dividual. Person-to-person trans­mission is common in health care settings (called nosocomial trans­mission) where proper personal protective equipment (PPE) is not available or not used. Lassa virus may be spread in contam­inated medical equipment, such as reused needles.

The signs and symptoms of Lassa fever typical­ly occur 1-3 weeks after the pa­tient comes into contact with the virus. Mild symptoms include slight fever, general malaise and weakness, and headache. More serious symptoms include hem­orrhaging (in gums, eyes, or nose, as examples), respiratory dis­tress, repeated vomiting, facial swelling, pain in the chest, back, and abdomen, and shock. Neuro­logical problems have also been described, including hearing loss, tremors, and encephalitis. Death may occur within two weeks af­ter symptom onset due to multi-organ failure (CDC).

Lassa fever is most often diag­nosed by using enzyme-linked immunosorbent serologic as­says (ELISA), which detect IgM and IgG antibodies as well as Las­sa antigen. Reverse transcription-polymerase chain reaction (RT-PCR) can be used in the early stage of disease. The virus itself may be cultured in 7 to 10 days, but this procedure should only be done in a high containment laboratory with good laboratory practices. Immunohistochemis­try, performed on formalin-fixed tissue specimens, can be used to make a post-mortem diagnosis. Because prevention is better than treatment and cure, there is need for efficient and effective pre­vention of Lassa fever. 

“Prima­ry transmission of the Lassa vi­rus from its host to humans can be prevented by avoiding con­tact with Mastomys rodents, es­pecially in the geographic regions where outbreaks occur. Putting food away in rodent-proof con­tainers and keeping the home clean help to discourage rodents from entering homes. Using these rodents as a food source is not recommended. Trapping in and around homes can help re­duce rodent populations.

*Emereonye is a commentator on public issues