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Routine immunisation and awareness would reduce yellow fever outbreak


Yellow Fever

The Nigeria Centre for Disease Control (NCDC), recently confirmed that nine persons died of yellow fever outbreak in Kwara, Nasarawa, Kano, Niger, Kebbi, Kogi and Zamfara States.In its situation report on yellow fever in the country released for the first epidemiological week in 2018, NCDC said the ailment has so far been confirmed in 12 local government areas across seven states.

Described as an acute systemic illness, the disease is usually caused by a virus called flavivirus. In severe cases, the viral infection causes a high fever bleeding into the skin, and necrosis death of cells in the kidney and liver. The damage done to the liver from the virus result in a severe condition of the patient, which makes the skin yellow.Health experts say it has no cure, although antiviral medications may be tried. Non-aspirin pain relievers, rest, and rehydration with fluids also decrease the discomfort.

Yellow fever can be prevented by vaccination. It is recommended for people travelling to or living in tropical areas, where yellow fever occurs. And because it is a live vaccine, it should not be given to infants or people with immune-system impairment.The experts also advised parents to always take their children, especially newborn babies, to primary health care within nine months for routine immunisation programme, as this would help to reduce yellow fever outbreak in the country.


On October 23, 1969, the Virus Research Laboratory of the University of Ibadan was notified that cases of suspected yellow fever had occurred in Jos, Plateau State. The diagnosis was confirmed by virus isolation and the existence of a widespread outbreak in Plateau and adjacent areas was established. This was the first recognised epidemic of yellow fever in Nigeria since1953. Between September and the end of December 1969, an estimated total of 252 patients with the ailment were hospitalised.

Dr. Ezekiel Sofela Oridota, a Senior lecturer and Consultant, Public Health Physician, Epidemiology and Biostatistics Unit, Department of Community Health and Primary Care, College of Medicine, University of Lagos and Lagos University Teaching Hospital (LUTH), Lagos, said signs and symptoms of yellow fever not different from those of malaria, as the patient would experience vomiting, tiredness, losts of appetite, back pains and headache.

He said: “Within three to six days of coming down with yellow fever, the patient begins to have the first set of signs and symptoms. In some people, it would result in aggressive symptoms for a day and then stop, which is referred to as self-limited, while others may not have any symptom at all. Some people would graduate to more serious ailments, which is when such other organs as the liver and kidney would be involved, especially the liver because this is where yellowness of the eyes begins to appear. At this stage, almost half of such patients would die, because this is where the organs begin to bleed.”

Oridota explained that yellow fever has a vaccine, which is extremely effective and is life-long. “This is where government needs to do more to create awareness,” he said. “The media also needs to be involved in this campaign in order to enlighten the people. Many people do not want to report disease outbreak in their communities, because they do not want their community to be labelled with such. But such stance will not help in eradicating disease outbreaks in the country. An immunised population is better than one not immunised, as routine immunisation is very effective.

“The disease itself does not have antiviral drugs that can be used to arrest it, but what we do is supportive treatments. This means treating the symptoms. For instance, if the patient is having pains and headache, we try to manage those problems, so that he/she can stay alive.” He reiterated the need for environmental sanitation and hygiene, which should be taken seriously, not during yellow fever outbreak, but on a daily basis.

“For instance, the Ebola Virus, lassa fever, and cholera outbreaks all have to do with personal hygiene and environmental sanitation. The aedes mosquito is the vector through which people contract yellow fever. So, it is advisable that people clean their environment and maintain personal hygiene by cleaning gutters and clearing stagnant water and bushes around homes.

“When people in the rural area fall ill, they tend to manage the sickness with self-medication, and before it is presented to health workers, it might be too late. Therefore, there is the need to see a doctor within two days of having any sickness. We should also strengthen our surveillance. For instance, once there is disease outbreak in Lagos, the response is faster than in other states. We need to work on information people have about their health. Some of the disease outbreaks we had was as a result of poverty and ignorance. There are many social problems that result in the outbreak of diseases. So, there is need for increased surveillance.”

Ebunoluwa Aderonke Adejuyigbe, a professor of paediatrics and former Dean of the Faculty of Clinical Sciences, Obafemi Awolowo University, Ile-Ife, said yellow fever is an acute viral haemorrhagic disease transmitted by aedes and hemagogues mosquitoes, which are infected by the causative agent.

She explained that the causative agent is an arbovirus from the Flavivirus family. The aedes mosquito that transmits it also transmits Zika and Dengue viruses. It breeds in tree holes and water in the forests, where it bites humans and non-human primates. It is also found in uncovered water reservoirs in communities and urban areas.

She said: “However, immunisation protects exposed humans, while unimmunised individuals come down with the disease. Unimmunised tourists, forest workers, farmers and campers bitten and infected in the forests and jungles become sources of transmission, when they return to their towns , cities and villages.

“Infants and children are at higher risk than adults. A case of mother to child transmission has also been reported. There is also a potential risk of transmission through blood transfusion and needlestick injuries, especially during epidemics. Signs and symptoms of yellow fever infection in most people are clinically inapparent, presenting with fever alone or with headache.

“For people who develop symptomatic illness, the incubation period is typically three to six days. The first phase of the illness presents as a nonspecific influenza-like syndrome, with sudden onset of fever, chills, headache, backache, myalgia, prostration, nausea, and vomiting which resolve in most patients.

“However, 15 percent of these patients enter a more serious or toxic form of the disease, characterised by jaundice, bleeding, and eventually shock and multisystem organ failure 48 hours after the initial improvement. The bleeding in these patients manifests as hematemesis, melena, metrorrhagia, hematuria, petechiae, ecchymoses, epistaxis, and oozing blood from the gingiva and needle-puncture sites. The case-fatality ratio for severe cases with when the kidney or liver is affected is 20 per cent to 50 per cent.”

She explained that treatment is mainly supportive and involves prompt treatment of symptoms as they manifest. For instance, if the bleeding becomes severe, the patient can be given blood transfusion, and if there is kidney failure, dialysis can be done.

“The most effective prevention strategy is immunisation, which is free, safe and provides life-long immunity,” she said. “It is given as part of routine childhood immunisation and to travellers from low-risk countries. It is also given to large populations, when they are affected by yellow fever epidemic as mass vaccination.

“Another prevention modality is the control of mosquitoes population by draining collections of water, where mosquitoes breed in neighbourhoods, applying larvicides to kill young mosquito larva, application of insecticide in homes, personal prevention from mosquito bites by wearing long clothing that cover the ankles and wrists and usage of insecticide treated nets. The final prevention is emergency preparedness by effective surveillance of yellow fever outbreaks and prompt response by mass vaccination campaigns and treatment of infected patients.”


Adejuyigbe said government’s efforts are key to prevention, by ensuring sustenance of routine infant immunisation, as epidemics would not occur, if over 80 per cent of the population is immunised. She said: “Effective disease surveillance and availability of confirmatory diagnostic laboratories, instead of having to send samples to Dakar, Senegal for confirmation is necessary. Prompt response to outbreaks by conducting mass vaccination campaigns and treating infected individuals is also crucial.

“Educational campaigns during outbreaks are important, so that infected individuals can quickly identify the symptoms and present at a health facility. Improving healthworkers’ skills during outbreaks in disease identification and management by brief refresher trainings is vital.“My advice to the public is to take advantage of government efforts at immunisation of infants and adults, as well as ensure immunisation, when travelling to countries with previous outbreaks.

“People should deprive mosquitoes of breeding spots in the neighbourhoods by emptying cans, containers, water puddles and spraying larvicides into those that cannot be drained.“There is also personal prevention from mosquito bites by applying mosquito repellent creams and wearing long covering clothings, especially in the evenings and when on camping trips, as well as prompt presentation to health facilities, when having suggestive symptoms.”

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