From bats to rats as Lassa takes off where Ebola stoped
By Sola Ogundipe
IN an ironical twist of fate, West Africa has been declared free of the two-year Ebola epidemic just as the sub-region is facing a renewed disease epidemic threat in the guise of Lassa fever. For most West Africans, particularly Nigerians that had an unpalatable taste of the devastating Ebola outbreak, it isn’t yet time to heave a sigh of relief. The West African Ebola outbreak was the worst in history. Between December 2013 and November 2015, Ebola infected almost 29,000 people and claimed 11,315 lives across the sub-region and even beyond.
Nigeria recorded nine deaths out of a total of 20 confirmed Ebola cases. On Thursday, Liberia, the worst Ebola-hit country with 4,800 deaths, got the all-clear from the World Health Organisation. West Africa is Ebola free, but no one can heave a sigh of relief because Lassa fever is taking over where Ebola has left off. And it has begun with Nigeria.
Like a bad dream, Lassa fever has turned up in Nigeria for the third time within a decade. Since the last quarter of 2015, the country has been battling the epidemic disorder, which at the last count, has reached 10 states and killed 43 people. More than 400 suspected cases have so far been recorded in the Borno, Gombe, Yobe, Taraba, Plateau, Nasarawa, Ebonyi, Edo, Ondo, Rivers, Anambra, Lagos and the FCT out of which around 90 cases have been confirmed.
Last week, the Federal government created the Lassa Fever Rapid Response Committee, whose goal is to control and prevent the spread of the disease. Public health officials have also asked Nigerians to stop burning bushes as this drives rats out of the bush and into nearby houses. Also just like Ebola, health care workers are predominantly infected and likely to die from Lassa fever infection, most often due to poor medical practices, late diagnosis, and treatment. The federal government has quickly stepped in with series of measures.
GOVT BANS CONSUMPTION OF RATS
It has placed a ban on consumption of rats that are a delicacy common to some states in the Middle Belt region of the country to curtail the spread of the disorder. Now it’s from Ebola fever to Lassa fever. In effect, what this translates to is from bats to rats! What can be good about rats? Nothing is the simple straight answer, except if one considers that they eat garbage. Rats are associated with dirty, smelly and unhygienic environments such as compost heaps, gutters, sewers and the like. When people think of rats what come to mind are pictures that are disgusting, dirty, and creepy.
But, bad as rats are, they live right alongside humans, eating the food, damaging household and office furniture, and leave droppings and urine markings all over the place. Rats are parasites because they live off humans without providing anything of worth”, in other words, rats are good for nothing and nothing is good about rats.
Unlike Ebola, Lassa fever is not new to Nigerians. The first ever documented case of Lassa fever was reported in Nigeria in 1969 when two missionary nurses died in a town called Lassa in the part of Nigeria now known as Borno State . They had complaints of weakness, headaches, fever and general malaise. An acute viral illness, Lassa fever has so far claimed 43 lives from just under 100 reported cases in 10 states of the country and the FCT.
Ebola fever and Lassa fever share so many common characteristics, they could be described as siblings, however, they are essentially different illnesses. They are classified as haemorrhagic fevers, because they cause severe haemorrhaging in victims. Both are caused by viruses that belong to the same Arenaviridae virus family. The Ebola and Lassa viruses are zoonotic in nature and of Africa origin.
BETWEEN EBOLA AND LASSA
While the Ebola virus lives mainly in the fruit bat, it is the “soft-furred rat” (multimammate rat) also known as Mastomys natalensis, that carries the Lassa virus. These rats are widespread throughout the West African region, breed frequently and bear many offspring, increasing the potential for spread of the virus from rats to humans. They are often found in human homes and transmission through contaminated food is common, as the rats usually leave urine and excrements in food stores.
TRANSMISSION AND SYMPTOMS
Just like the Ebola virus, the Lassa virus is transmitted through close contact with the virus host or the sweat, vomit, blood or other bodily fluids of an infected person, or the recently deceased. Both cause severe fever and muscle pain, weakness, vomiting and diarrhoea. In many cases they shut down organs and cause unstoppable internal bleeding. Patients often succumb within 3-21 days.
But unlike Ebola, Lassa is different because it is treatable with Ribavirin – an antiviral drug, that is only effective if administered within the first six days after the disease onset. Lassa fever patients also benefit from careful monitoring of fluid, electrolyte and oxygen levels.
People usually become infected with Lassa virus from exposure to infected rodents. Person-to-person transmission occurs through direct contact with sick patients in both community and health care settings. Those at greatest risk are persons living in rural areas where Mastomys are found. Health care workers are at risk if adequate infection control practices are not maintained.
Last week, the Nigerian federal government created the Lassa Fever Rapid Response Committee, whose goal is to control and prevent the spread of the disease. Public health officials have also asked Nigerians to stop burning bushes as this drives rats out of the bush and into nearby houses.
Humans usually become infected with Lassa virus from exposure to urine or faeces of infected Mastomys rats. Lassa virus may also be spread between humans through direct contact with the blood, urine, faeces, or other bodily secretions of a person infected with Lassa fever. There is no epidemiological evidence supporting airborne spread between humans. Person-to-person transmission occurs in both community and health-care settings, where the virus may be spread by contaminated medical equipment, such as re-used needles. Sexual transmission of Lassa virus has been reported.
Lassa fever occurs in all age groups and both sexes. Persons at greatest risk are those living in rural areas where Mastomys are usually found, especially in communities with poor sanitation or crowded living conditions. Health workers are at risk if caring for Lassa fever patients in the absence of proper barrier nursing and infection control practices.
The furry rat , once infected, is able to excrete virus in urine for an extended time period, maybe for the rest of its life. The typical rodents breed frequently, produce large numbers of offspring, and are numerous in the savannas and forests of west, central, and east Africa. They readily colonize human homes and areas where food is stored. It is known that worldwide, rats spread diseases directly and indirectly. An example of direct transmission is the rat’s habit of “urine marking” for sexual advertisement and habitat labelling. This leaves tiny tell-tale droplets all over surfaces.
RATS SHARE FOOD AND SHELTER WITH MAN
To sum it up in the words of the CDC: “Rodents destroy property, spread disease, compete for human food sources, and are aesthetically displeasing”. They are clearly not one of the most beloved animals. Rats consume untold tons of refuse every year, leaving less waste. Some estimates say there is one rat for every human in big cities like Lagos, Abuja, Port Harcourt, and others. That may be too many rats to think about, there are actually hundreds of millions roaming around Lagos alone.
Rodents share food and shelter with man. They are parasites in the workplaces, restaurants, hospitals, schools, food processing plants and especially the homes. They share the food and the furniture and home. They will use plumbing voids as well as circulation vents to travel from one part of a home/building to another. It is this habit that assures the spread of contaminated nesting material, faeces, and urine and body hairs.
They destroy property, spread disease, compete for human food sources, and are aesthetically displeasing. As long as there is garbage to get rid of, man will not be getting rid of rats soon Rats have been responsible for some of the most devastating disease outbreaks known. Medical literature says rats and mice could spread about 55 different diseases. Lassa fever Lyme disease, Typhus and the Plague are just a few.
Human behaviour could be a major contributing factor in the transmission of deadly infections such as Ebola and Lassa fever, based on interactions between humans, domestic animals, wildlife and the environment. A school of thought is convinced that humans need to not just consider rats as the villains, because ultimately humans are just as much the villains as rats. These are other factors could ultimately contribute to the relatively efficient spread of Lassa virus from infected rodents to humans. Oh yes, it’s hard to find anything good to say about rats!