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How to escape Lassa fever

Doris Obinna

Again, Nigeria is faced with a health challenge that is drifting to epidemic. It is a situation, which has put government, at the federal and state levels, on their toes. It has visited some states of the federation and taken casualties. It is Lassa fever.

Last year, no fewer than 18 states in the country experienced outbreak of Lassa fever. There were some 241 cases, with 82 deaths by August 2017. The outbreak had started around December 2016 and ravaged Plateau, Ebonyi, Ondo, Edo, Taraba, Nasarawa, Rivers, Ogun and Bauchi states. Others are Borno, Kano, Kogi, Enugu, Anambra, Kaduna, Gombe, Cross-River and Lagos.

This year, 10 states have been visited by Lassa fever, with a total of 107 cases. The affected states are Ebonyi, Imo, Edo, Ondo, Bauchi, Nasarawa, Anambra, Benue, Kogi and Lagos States. There have been confirmed 16 deaths. Incidentally, about 10 health care workers were infected in Ebonyi (7), Nasarawa (1), Kogi (1) and Benue (1). Three of them died in Ebonyi State.

Following the increasing number of Lassa fever cases reported from several as response to the Lassa fever outbreak, the Nigeria Centre for Disease Control activated its Emergency Operations Centre (EOC) to tackle the problem, on behalf of the Federal Ministry of Health. It dispatched Rapid Response Teams to three states considered as mostly affected: Ebonyi, Ondo and Edo States, with the mandate to support response coordination, contact tracing, case management, risk communication and strengthening infection prevention and control practices.

In the assignment, NCDC is collaborating with the World Health Organisation (WHO), Federal Ministry of Agriculture and Rural Development, Irrua Specialist Teaching Hospital, African Field Epidemiology Network, US Centers for Disease Control, University of Maryland Baltimore (UMB), Alliance for International Medical Action (ALIMA) and other agencies.

Lassa fever first occurred in Nigeria, in Borno State, in a town called Lassa, hence the name. It almost claimed a life in the community.   Indeed, human arenavirus infection began in 1969 in Africa, with the mysterious death of two medical missionaries. In investigating the cause of death, an arenavirus was isolated from two of these patients and given the name of Lassa virus, after the town of Lassa, in Borno State.

Lassa fever or Lassa hemorrhagic fever (LHF) is an acute viral hemorrhagic fever caused by the Lassa virus and is a member of the arenaviridae virus family. It is a single-stranded RNA virus. It is zoonotic or animal-borne, meaning that humans become infected from contact with infected animals.

Similar to Ebola, clinical cases of the disease have been known for over a decade but have not been connected with a viral pathogen. Lassa fever is endemic in parts of West Africa and ravaged countries, like Liberia, Guinea, Nigeria and Sierra Leone. There have been isolated cases in Mali,  Benin, Burkina Faso, Cote d’Ivoire and Togo.

Neighboring countries are also at risk due to the animal vector for Lassa virus. The animal is the Multimammate rat or Mastomysnatalensis, which is distributed throughout the region as a whole. In 2009, Mali reported its first case in a traveller who was living in southern Mali. Ghana reported its first cases in 2011. Isolated cases have been reported in Cote d’Ivoire and Burkina Faso.

The number of people who experience Lassa fever each year in West Africa is estimated to be between 100, 000 and 300, 000, with around 5, 000 people dying from the virus. The estimates are crude because surveillance for cases of the disease is not performed uniformly. In some areas of Liberia and Sierra Leone, approximately 10 to 16 per cent of those admitted to hospitals each year have Lassa fever, which indicates the serious impact of the virus on the population of these areas.

World Health Organisation (WHO), reveals that about 80 per cent of people who become infected with Lassa virus have no symptoms. One in five infections results in severe disease, where the virus affects several organs such as the liver, spleen and kidneys.

Speaking on Lassa fever, Chief Executive Officer, Nigeria Centre for Disease Control (NCDC), Dr. Chikwe Ihekweazu, said the disease is an acute viral haemorrhagic illness, transmitted to humans through contact with food or household items contaminated by infected rodents. He said person-to-person infections and laboratory transmission can also occur, particularly in hospitals lacking adequate infection prevention and control measures.

“It can also occur, particularly in hospital environment in the absence of adequate infection control measures. Health care workers in health facilities are particularly at risk of contracting the disease, especially where infection prevention and control procedures are not strictly adhered to,”  he said.

Signs and symptoms

The incubation period of Lassa fever ranges from 6 to 21 days. The onset of the disease, when it is symptomatic, is usually gradual, starting with fever, general weakness, and malaise. After a few days, headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhoea, cough, and abdominal pain may follow.

Also, in severe cases, there is facial swelling, fluid in the lung cavity, bleeding from the mouth, nose, vagina or gastrointestinal tract and low blood pressure may develop.

Protein may be noticed in the urine. Shock, seizures, tremor, disorientation, and coma may be seen in the later stages. Deafness occurs in 25 per cent of patients who survive the disease. In half of these cases, hearing returns partially after one to three months. Transient hair loss and gait disturbance may occur during recovery. Death usually occurs within 14 days of onset in fatal cases.

The disease is especially severe late in pregnancy, with maternal death and or fetal loss occurring in more than 80 per cent of cases during the third trimester.

Other signs may include; abdominal pain, back pain, conjunctivitis, mucosal bleeding and proteinuria

Diagnosis

Because the symptoms of Lassa fever are so varied and non-specific, clinical diagnosis is often difficult, especially early in the course of the disease. Lassa fever is difficult to distinguish from other viral haemorrhagic fevers, such as Ebola virus disease as well as other diseases that cause fever, including malaria, shigellosis, typhoid fever and yellow fever.

Definitive diagnosis requires testing that is available only in reference laboratories. Laboratory specimens may be hazardous and must be handled with extreme care.

Lassa virus infections can only be diagnosed definitively in the laboratory using the following tests: reverse transcriptase polymerase chain reaction (RT-PCR) assay, antibody enzyme-linked immunosorbent assay (ELISA), antigen detection tests and virus isolation by cell culture.

 

Prevention

Lassa fever, according to Ihekweazu, can be prevented through practicing good personal hygiene and proper environmental sanitation. Effective measures include storing grain and other foodstuffs in rodent-proof containers, disposing of garbage far from the home, maintaining clean households, and other measures to discourage rodents from entering homes. Hand washing should be practiced frequently.

He said: “Health care workers are again reminded that Lassa fever presents initially like any other disease causing a febrile illness, such as malaria; and are advised to practice standard precautions at all times, maintaining a high index of suspicion. Rapid Diagnostic Test (RDT) must be applied to all suspected cases of malaria. When the RDT is negative, other causes of febrile illness, including Lassa fever should be considered. Accurate diagnosis and prompt treatment increase the chances of survival.

“Family members who are providing care for patients with Lassa fever should take extra caution. In addition, States are encouraged to ensure safe and dignified burial practices for patients who die from Lassa fever.”

 

Treatment

Ribavirin, is an antiviral drug that has been used with success in people affected by Lassa fever. It has been shown to be most effective when it is administered early in the course of the illness. People should also receive supportive care that consists of maintenance of, Oxygenation, blood pressure, treatment of complicating infections and appropriate fluid and electrolyte balance.

The antiviral drug ribavirin seems to be an effective treatment for Lassa fever if given early on in the course of clinical illness. There is no evidence to support the role of ribavirin as post-exposure prophylactic treatment for Lassa fever. There is currently no vaccine that protects against Lassa fever.

When contacted, see your doctor or a specialist immediately.

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