Lassa Fever is a very serious illness that has largely been restricted to areas of West Africa. It was first identified in 1969, and is caused by the now named Lassa virus, which can be transmitted directly from person-to-person. Usually, the more direct form of transmission of Lassa virus is through contact with infected animals, via eating the droppings or urine (when food is not stored safely), by touching droppings or urine that is infected, or by having open wounds and sores that come into contact with these substances, which are the product of a specific rat species, called the multimammate rat. Inhalation of droppings may also cause infection.
Unfortunately, these rats are known for their ability to inhabit homes, and where homes are not airtight, or where proper food storage is impossible, contact with these animals can occasionally result in Lassa Fever outbreaks. It’s hard to get specific estimates of death rates due to the virus, because not all areas where Lassa Fever may occur have reliable diagnostic methods or consistent methods of reporting the illness. Nevertheless, estimates suggest about 5000 people die each year from Lassa Fever, and anywhere from 100,000-500,000 people get the virus.
It’s important to understand that in about 80% of the contracted cases, there may be few symptoms present and people get well quickly. For as yet unexplained reasons, some people, as with the West Nile Virus, are particularly vulnerable to the illness and get very serious symptoms. For pregnant women the disease is very dangerous. In the first three months of pregnancy, contraction of the virus will lead to miscarriage in many cases, and in later stages of pregnancy, risk to both mother and child frequently results in death of both mom and unborn child
When Lassa Fever is serious, people may experience a wide variety of symptoms that include pain throughout the body, sore throat, fever, a bad cough, diarrhea, infected eyes, and bleeding from the nose and stomach. Like the Ebola Virus, Lassa Fever is called a hemorrhagic fever because it can cause multi-organ system failure and may result in severe bleeding. Sometimes this virus may also cause encephalitis, or neurological symptoms like severe tremor. The virus is also call zoonotic because normal transmission is through contact with infected animals. Viruses transmitted from animals to humans are called zoonoses.
Recovery from the virus is usually without complication, but some people have residual deafness when they get better. The disease can be diagnosed and identified by looking at blood samples but this is not always done. This is especially the case because symptoms can be so varied.
Normal treatment for Lassa Fever is with antiviral drugs, which unfortunately in poorer countries like Sierra Leone may be unavailable. The drug Ribavirn®, is considered most effective, especially when the fever is diagnosed early and treatment begun immediately. Medical researchers are working on a vaccine, but again, the issue of vaccine availability may be problematic in poorer or destabilized countries.
For travelers, especially pregnant women, it’s important to weigh the risks versus benefits of entering an area that has Lassa Fever outbreaks. Discuss risks and travel plans with your obstetrician prior to making a decision on travel plans, since as yet, there is no vaccine to prevent the illness.