With the trend of things now, the fear of Lassa fever seems to be the beginning of wisdom. This is notwithstanding that the Federal Ministry of Health through the project director, National Centre for Disease Control (NCDC), Abdulrahman Nasidi, had stated in an interview that given the current level of the disease, it would be too hasty to declare a national emergency – as was done in the case of Ebola. Despite this assurance, the citizens have continued to live in fear, and rightly so, as the statistics are staggering. For the past six weeks, Nigeria has been experiencing Lassa fever outbreak which has so far affected 10 states. The states affected include Bauchi which recorded the first case in November 2015, Nasarawa, Niger, Taraba, Kano, Rivers, Edo, Plateau, Gombe and Oyo States. At the last count, it was confirmed that the disease has claimed the lives of 40 people with not less than 80 reported cases.
Lassa fever, a haemorrhagic disease, was named after Lassa village in Borno State, northeastern Nigeria, where it was first discovered in 1969. The disease occurs more in the dry season than the rainy season. It is caused by a species of rodents called Natal multimammate rat, the common African rat, or the African soft-furred rat. The Lassa virus is transmitted when the droppings, that is the urine or faeces, of the rat – the natural reservoir for the virus – comes in contact with foodstuff or in the process of the rat accessing grain stores, either in silos or in residences. The rodents live in houses with humans and deposit excreta on floors, tables, beds and food. Consequently the virus is transmitted to humans through cuts and scratches, or inhaled via dust particles in the air. In some regions these rodents are also consumed as food. Secondary transmission of the virus between humans occurs through direct contact with infected blood or bodily secretions. This occurs mainly between individuals caring for sick patients, although anyone who comes into close contact with a person carrying the virus is at risk of infection. Nosocomial transmission, that is the transmission that occurs as a result of treatment in a hospital and outbreaks in healthcare facilities in endemic areas, represents a significant burden on the healthcare system.
In the early stages, Lassa fever is often misdiagnosed as common cold, typhoid or malaria, and as a result many patients fail to receive appropriate medical treatment. Making a correct diagnosis of Lassa fever is made difficult by the wide spectrum of clinical effects that manifest, ranging from asymptomatic to multi-organ system failure and death. The onset of the illness is typically mild, with no specific symptoms that would distinguish it from other febrile illnesses. In 80 percent of cases, the disease is without symptoms but in the remaining 20 percent, it takes a complicated course. It has an incubation period of six to 21 days after which an acute illness develops.
Early signs include fever, headache and general body weakness, followed by a sore throat, nausea, vomiting, abdominal pain and diarrhoea in some cases. After four to seven days, many patients will start to feel better, but a small minority will present with multi-organ involvement. It can affect the gastro-intestinal tract causing nausea, vomiting and stooling of blood as well as difficulty in swallowing. Cardiovascular system symptoms include hypertension or hypotension as well as abnormal high heart rate and shock. In the respiratory tract, the victim experiences chest pains, cough and difficulty in breathing. The virus also causes difficulty in hearing, meningitis and seizures. Symptoms such as swellings, hypertension, bleeding and shock are also present. Death from Lassa fever most commonly occurs 10 to 14 days after symptom onset. Non-specific symptoms are facial swelling and muscle fatigue, as well as conjunctivitis and mucosal bleeding. And one of the hallmarks of Lassa virus infection is the absence of functional antibodies during acute infection.
Lassa fever is endemic to West Africa. Confirmed incidences have been recorded in Sierra Leone, Liberia, Guinea, Nigeria and Mali. However, concerns exist that there may be Lassa(-like) viruses in other countries such as Central African Republic, Ghana, Mali, Ivory Coast, Togo, Benin and Cameroon due to trans-border migration. Furthermore, Mastomys rodents are distributed across the African continent, indicating a strong possibility for the spread of the disease they carry.
As mentioned earlier, clinical diagnosis of Lassa fever infections are difficult to distinguish from other viral haemorrhagic fevers such as Ebola, and from more common febrile illnesses such as malaria, but 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 – PCR (RT-PCR) – is routinely used for confirmation of cases. The virus is excreted in urine for three to nine weeks and in semen for three months. No vaccine for Lassa fever is currently available for use in humans.
There are three ways by which the virus can be treated and also prevented from further spread. These are implementation of barrier nursing, that is, isolation of victims, tracing of people that have come in contact with sufferers as well as the initiation of treatment with the only available drug, Ribavirin. The latter is only effective if administered early, within the first six days after disease onset.
Therefore, it is essential that preventive measures be put in place to prevent this fatal disease. Firstly, the primary source of transmitting the disease to humans should be prevented. This can be possible through avoiding contact with rats – particularly in the geographic areas where outbreaks happen. Putting food away in rat-proof containers and keeping your home clean help with discouraging rats from entering your home. Using these rats as a source of food is definitely not recommended. Trapping around and in homes may help to reduce rat populations.
While providing care for people with Lassa fever, further transmission of the disease through person-to-person contact or other routes may be avoided by taking preventative precautions against contact with secretions from infected persons, called ‘VHG isolation precautions’ or barrier nursing methods. The precautions include wearing protective clothing such as masks, gowns, gloves and goggles, using infection control measures such as the sterilization of equipment. It is vital to isolate infected people from contact with unprotected persons until the disease has run its course.
In addition, all states’ Ministries of Health and Information have a lot to do in educating people who live in high-risk areas as well as those not presently affected about ways to lower the rat populations in their homes which will go a long way in controlling and preventing Lassa fever from gaining ground in the country. With the array of challenges currently facing our beloved country, we cannot afford to treat the outbreak of Lassa fever with kid gloves.
BILKIS BAKARE
