|Year : 2017 | Volume
| Issue : 1 | Page : 1-5
Lassa fever: Unveiling the misery of the Nigerian health worker
Department of Obstetrics and Gynaecology, Ahmadu Bello University, Ahmadu Bello University Teaching Hospital, Zaria, Kaduna State, Nigeria
|Date of Web Publication||15-Feb-2018|
Department of Obstetrics and Gynaecology, Ahmadu Bello University, Ahmadu Bello University Teaching Hospital, Zaria, Kaduna State
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mustapha A. Lassa fever: Unveiling the misery of the Nigerian health worker. Ann Nigerian Med 2017;11:1-5
There is an ongoing outbreak of Lassa fever, a viral hemorrhagic fever (VHF), in Nigeria. VHF is a diverse group of animal and human illnesses characterized by fever and hemorrhage and are caused by five distinct ribonucleic acid virus families. These highly infectious viruses lead to a potentially lethal disease syndrome characterized by fever, malaise, vomiting, mucosal and gastrointestinal (GI) bleeding, edema, and hypotension. The term is usually applied to disease caused by Arenaviridae (Lassa fever, lymphocytic choriomeningitis virus, Lujo, Guanarito, Machupo, Junin, Sabia, and Chapare), Bunyaviridae (Crimean–Congo hemorrhagic fever, Rift Valley Fever, and Hantaan hemorrhagic fevers), Filoviridae (Ebola and Marburg), and Flaviviridae (yellow fever, dengue, Omsk hemorrhagic fever, Kyasanur forest disease, and Alkhurma viruses).,
Lassa fever virus is an old world Arenavirus that causes an acute febrile illness, with bleeding and death in severe cases. According to the World Health Organization (WHO), it is an acute viral hemorrhagic illness of 2 to 21 days' duration that occurs largely in West Africa. This virus has a both a large and a small genome section, with four lineages identified to date: Josiah (Sierra Leone), GA391 (Nigeria), LP (Nigeria), and strain AV.
The zoonotic Lassa fever virus was first described in 1969 from a case in a missionary nurse in the town of Lassa, in Borno State, Nigeria, hence its name. The reservoir or host of the Lassa fever virus, the multimammate rat called Mastomys natalensis, shed the virus in urine and feces, hence can be transmitted to humans through direct contact, or through cuts or sores. Person-to-person infections and laboratory transmission can also occur, particularly in hospitals lacking adequate infection prevention and control measures; the common scenario in our hospitals!
Lassa fever is hyperendemic in parts of West Africa including Sierra Leone, Liberia, Guinea, and Nigeria; however, other neighboring countries are also at risk, as the animal vector for Lassa virus, the multimammate rat is distributed throughout the region. In 2009, the first case from Mali was reported in a traveler living in Southern Mali; Ghana reported its first cases in late 2011. Isolated cases have also been reported in Côte d'Ivoire and Burkina Faso, and there is serologic evidence of Lassa virus infection in Togo and Benin. In 2017, Benin, Burkina Faso, Sierra Leone, and Togo experienced outbreaks that have since been controlled. Seasonal outbreaks occur annually between December and June, the dry season in Nigeria. The number of Lassa virus infections per year in West Africa is estimated at 100,000–3,000,000, with approximately 5000 deaths. Unfortunately, such estimates are crude, because surveillance for cases of the disease is not uniformly performed. In some areas of Sierra Leone and Liberia, it is known that 10%–16% of people admitted to hospitals every year have Lassa fever, which indicates the serious impact of the disease on the population of this region.
A suspected case of Lassa fever describes any individual presenting with one or more of the following: malaise, fever, headache, sore throat, cough, nausea, vomiting, diarrhea, myalgia, chest pain, hearing loss, and either (a) history of contact with excreta or urine of rodents and (b) history of contact with a probable or confirmed Lassa fever case within a period of 21 days of onset of symptoms or any person with inexplicable bleeding/hemorrhage. A confirmed case is any suspected case with laboratory confirmation (positive-IgM antibody, polymerase chain reaction [PCR], or virus isolation). A probable case is any suspected case (see definition above) but who died without collection of specimen for laboratory testing. “Active” means where there has been at least one confirmed case and contacts within 21 days' postexposure.
In 2016, Nigeria reported 273 suspected cases and 149 deaths (case fatality rate – 55%) from 23 states. According to Nigeria Centre for Disease Control (NCDC), during the 2017 outbreak, 19 out of 36 States reported at least one confirmed case each. The NCDC, NCDC in the situation report for Epi-week 04 in January 2018, said from 1st to 25th January 2018, a total of 297 suspected cases, and 22 deaths have been reported from 13 active States (Edo, Ondo, Bauchi, Nasarawa, Ebonyi, Anambra, Benue, Kogi, Imo, Plateau, Lagos, Taraba, and Delta). Since the beginning of 2018, 80 cases have been classified as follows: 77 confirmed cases, 3 probable cases with 21 deaths (18 in confirmed, and 3 in probable cases. In the reporting week 4 (January 22–28, 2018), 15 new confirmed cases and two deaths were recorded from five States Edo (6), Ondo (4), Delta (1), Imo (1), and Taraba (3). Case fatality rate in confirmed and probable cases is 27.6% and 7.4% for all cases (including probable, confirmed, and suspected). According to the health agency, as at January 28, 2018, 10 out of the 77 confirmed cases were health-care workers from four states Ebonyi-7, Nasarawa-1, Kogi-1, and Benue-1, out of which 4 are now deceased.
In Nigeria, the Lassa fever situation initially improved with the implementation of Lassa virus PCR testing at a research laboratory of the University of Lagos, which facilitated retrospective laboratory confirmation of Lassa fever cases in various parts of the country. However, none of the hospitals in the endemic areas of Nigeria still has the capacity to perform Lassa virus tests. Case management is thus mainly based on nonspecific clinical criteria, and in the worst cases, health-care workers became infected while they treated patients without knowing they had Lassa fever.
In 2001, Irrua Specialist Hospital (ISTH), Edo State was designated as a Centre of Excellence in the management of Lassa fever, along with two other federal tertiary health institutions. It set up awareness campaigns to sensitize hospital staff and the public to the severity of Lassa fever infection and need for treatment and prevention. Ribavirin was periodically supplied to the hospital by the Federal Ministry of Health and given to suspected cases. Prevalence and case fatality figures based on clinical suspicion and pilot laboratory investigations in 2003 and 2004 suggested a high incidence of Lassa fever in Edo State, but the true magnitude of the problem remained obscure. In 2007, the management of ISTH was dissatisfied with the level of response and attention given to Lassa fever and took bold steps to address the situation. Among these steps, was the establishment of Institute of Lassa Fever Research and Control. The rationale for the institute was based on the need to build capacity to adequately respond to the epidemics observed in the region in terms of workforce development and training, laboratory diagnosis, and adequate case management as well as the dire need for focused research and advocacy. A collaborative effort was made to establish a laboratory for molecular diagnostics of Lassa fever, which was considered crucial for appropriate case and contact management, including early treatment and postexposure prophylaxis with ribavirin. The diagnostic and research laboratory started operation in September 2008. It currently has 43 cases on admission as at January 28. The Federal Medical Centre, Owo has 18 isolation beds, all occupied with Lassa Fever cases, to show the enormity of the outbreak. Doctors in ISTH are also providing clinical management advise for other hospitals. The National Lassa fever Emergency Operations Centre (EOC) continues to coordinate the response according to the NCDC. Letters of notification of Lassa fever EOC activation has been sent to all states of Nigeria and a 24-hour Lassa fever case management helpdesk is currently available.
About 80% of human infections are without symptoms; the remaining cases have severe multiple organ disease, where the virus affects several organs in the body, such as the liver, spleen, and kidneys. According to the WHO, the onset of the disease, when it is symptomatic, is usually gradual, starting with fever, general weakness, muscle and joint pains, prostration, and malaise. After a few days, headache, sore throat from pharyngitis, muscle pain, retrosternal pain, nausea, vomiting, diarrhea, cough, and abdominal pain may follow. Hearing loss is common in adults (among those who survive about a quarter have deafness which improves over time in about half). Anasarca is common in newborns. Spontaneous abortion and birth defects have been documented. When Lassa fever infects pregnant women late in their third trimester, induction of labor is necessary for the mother to have a good chance of survival. This is because the virus has an affinity for the placenta and other highly vascular tissues. The fetus has only a one in ten chance of survival no matter what course of action is taken; hence, the focus is always on saving the life of the mother. Following delivery, women should receive the same treatment as other Lassa fever patients. In severe cases, facial edema, pulmonary edema, bleeding from the mouth, nose, vagina, or GI tract, and low blood pressure may develop. Shock, seizures, tremor, disorientation, and coma may be seen in the later stages. The virus is excreted in urine for 3–9 weeks and in semen for 3 months. Lassa fever virus can also be found in cerebrospinal fluid.
Laboratory abnormalities include elevations in aspartate aminotransferase liver enzyme, the initial drop in leukocyte count, and thrombocytopenia. Because the incubation period may be as long as 21 days, the patients may not develop illness until returning from travel – just as in the index case in Nigeria; therefore, a thorough travel and exposure history is critical.
Lassa fever is most often diagnosed using enzyme-linked immunosorbent serologic assays, which detect IgM and IgG antibodies (give 88% sensitivity and 90% specificity for the presence of the infection) as well as detecting the Lassa antigen. Reverse transcription-PCR can be used in the early stage of disease. The virus itself may be cultured in 7–10 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 postmortem diagnosis. Plaque neutralization assays can also be done. The confidence of a diagnosis can be compromised if laboratory tests are not available. One comprising factor is the number of febrile illnesses present in Africa, such as malaria and typhoid fevers, both endemic in the country, which could potentially exhibit similar symptoms, particularly for nonspecific manifestations of Lassa fever. In cases with abdominal pain, in countries where Lassa is common, Lassa fever is often misdiagnosed as appendicitis and intussusception which delays treatment with the antiviral ribavirin. In West Africa, where Lassa is most prevalent, it is difficult for doctors to diagnose due to the absence of proper equipment to perform tests.
On January 14, this year, four cases of Lassa fever among health-care workers in Ebonyi State were reported at the NCDC. Three of the four cases – two medical doctors and a nurse have subsequently passed away, despite efforts to save their lives. According to the University Graduates of Nursing Science Association, at the latest count, more than 40 health workers have died as a result of Lassa fever in Ebonyi alone in the past 13 years. This is why a fully operational virology center is needed in Ebonyi state. Again, a medical doctor with the Federal Medical Centre, Lokoja, Kogi State who tested positive to Lassa fever, died of the disease late January 2018. With these poor and alarming statistics among health-care professionals in Nigeria, it is paramount to take proactive measures to reduce these infections and deaths. Some major stakeholders in the health sector have blamed these infections on “carelessness” among health workers who have “refused” to take necessary precautions while treating patients in hospitals. Responses to this statement have shown disappointment on the part of the health-care workers who described it as callous and insensitive, as simple gloves are sometimes not readily available in Federal Teaching Hospitals, with the miserable workers paying the ultimate price!
Notwithstanding, the resurgence of Lassa fever in the country should be a major source of worry as reports from some parts of the country are scary, especially because health workers are dying of the disease they are to cure. Health workers are most times secondary victims who get infected while treating patients with the disease. In West African subregion, Nigeria inclusive, where Lassa is most prevalent, it is difficult for doctors to diagnose due to the absence of proper equipment to perform tests.
Early supportive care with rehydration and symptomatic treatment improves survival chances. As such, the affected State Ministries of Health and the Federal Ministry of Health should respond to contain the current Lassa fever outbreak by mobilizing human and material resources to trace the sources and extent of the disease, follow-up on potential contacts, identify early, and test suspected cases. Most importantly, provide PPEs and rapid response for suspected cases.
Ribavirin is effective if given early in the course of disease for treating Lassa fever and other Old World Arenaviruses. The drug is relatively inexpensive, but the cost of the drug is still very high for many of those in West African states. Fluid replacement, blood transfusion, and fighting hypotension are usually required.
The current upsurge in the cases of Lassa fever in Nigeria demands urgent attention of governments at all levels. As such, all hands must be on deck to redress this situation. Personal Protective Equipment should be readily available at entry points of the hospital (Outpatient clinics, Labor wards, Accident, and Emergency) and response teams should be armed with materials needed to swing into action whenever there is a suspected case. Importantly, every fever must be investigated properly and treated appropriately, and malaria should not be treated without a diagnosis. The rapid diagnostic test (RDT) for malaria should be used, but its ready availability in hospitals will be another subject for discussion.
Researchers at the USAMRIID facility, where military biologists study infectious diseases, have a promising vaccine candidate. They have developed a replication-competent vaccine against Lassa virus based on recombinant vesicular stomatitis virus vectors expressing the Lassa virus glycoprotein.
Strategically, since there is currently no vaccine that protects against Lassa fever, prevention is a key. Its prevention relies on scientific interventions, societal and individual behavioral changes hinged on good hygiene. Individuals should learn to store grains and other foodstuff in rodent-proof containers, dispose of garbage far from the home, and maintain clean households. Health workers should maintain a high level of alert in the wake of this new outbreak and observe universal precautions in handling all suspected cases of this viral hemorrhagic fever. The scientific intervention requires a connect between town and gown. The Federal Ministry of Health, CDC in Nigeria, Nigerian Institute of Medical Research, Institute of Human Virology, Nigerian research and development units of health-related organizations such as pharmaceutical companies and universities should collaborate and engage in a well-coordinated manner to search for solutions through research on the species of rat that hosts the Lassa virus and how to make them de-zoonotic er to render them impotent as carriers. They should also lead a vaccine and treatment research, particularly now that the federal government recently said that Nigeria is set to resume local production of vaccines after 27 years! In addition, any institution or individual who has done any useful research should make it public. Furthermore, the relevant ministries, departments, and agencies of government at all levels should map the pattern of the outbreak with a view to preventing or dealing with the future occurrences.
Standard precautions and contact and droplet precautions for suspected Lassa fever patients are recommended to avoid transmission. Direct contact should be avoided with corpses of patients suspected of having died of Arenavirus infection.
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; however, the wide distribution of Mastomys in Africa makes complete control of this rodent reservoir impractical.
When caring for patients with Lassa fever, further transmission of the disease through person-to-person contact or nosocomial routes can be avoided by taking preventive precautions against contact with patient secretions (called VHF isolation precautions or barrier nursing methods). Such precautions include using PPEs such as masks, gloves, gowns, and goggles; using infection control measures, such as complete hand sanitization and equipment sterilization; and isolating infected patients from contact with unprotected persons until the disease has run its course.
Further, educating people in high-risk areas about ways to decrease rodent populations in their homes will aid in the control and prevention of Lassa fever. Other challenges include developing more RDT and increasing the availability of the only known drug treatment, ribavirin. Research is presently underway to develop a vaccine for Lassa fever.
Finally, the virology center built by the Ebonyi State Government 2 years ago should be made fully functional, to reduce the unnecessary and arduous ferrying of victims of Lassa fever from the East, by road to Irrua in Edo state, a process that often leads to death from exhaustion of some victims. In addition, more centers should be built in other parts of the country to curb the scourge during the future outbreaks.
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Conflicts of interest
There are no conflicts of interest.
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