The emergence of Yellow Fever, an acute viral haemorrhagic disease, which continues to cause high mortality rate in Africa, has refused to leave the shores of Africa despite the availability and administration of an effective vaccine for more than 70 years. The deadly disease has resurfaced in Nigeria bringing to fore an endemic concern for the Nigeria Centre for Disease Control (NCDC). The transmission of the virus in Africa is primarily through the bite of infected female Aedes and Haemogogus species of mosquitoes that breed around houses (domestic) in the wild, and in other habitats (semi-domestic), with humans as the main reservoirs of the dead-end host of the virus. The ‘Yellow’ in the virus named Yellow Fever is the reflection of jaundice that affects humans and the yellowing of the skin and eyes.
The World Health Organisation (WHO) estimates that the virus causes about 84, 000-170, 000 cases, with about 60, 000 deaths across the globe every year; whereas, more than 90 per cent of the cases occur in Africa. Once contracted, the yellow fever virus incubates in the human body for 3 to 6 days, with common symptoms like, fever, muscle pain, backache, headache, loss of appetite, and nausea or vomiting. A small percentage of patients enter a second, more toxic phase within 24 hours of recovering from initial symptoms. In the aforementioned phase, people are likely to develop jaundice, dark urine, abdominal pain and are more likely to vomit. Bleeding can occur from the mouth, nose, eyes or stomach. According to medical experts, half of the patients who enter the toxic phase die within 7 – 10 days.
The virus, which is largely prevalent in most African countries with tropical climates, is said to be on the rise due to decreased immunity among local populations, The prevalence is also attributed to deforestation, climate change, and high-density urbanization.
Nigeria is one of the African countries susceptible to the virus. The country has been battling successive outbreaks since September 2017, but has relied heavily on the support of the National Primary Health Care Development Agency (NPHCDA). The WHO has also assisted by obtaining donated vaccines through the International Coordinating Group (ICG) on Vaccine Provision, to help manage the provision of emergency vaccine supplies to countries, Nigeria inclusive, during major outbreaks.
The recent outbreak of the virus in some parts of the country has called for great concern as mortality rate has taken a spike. A record of no fewer than 72 deaths has been witnessed in Enugu and Delta States. When the current outbreak was first detected in both states, affected communities described it as a ‘strange disease’. The Nigeria Centre for Disease Control (NCDC) stepped in by carrying out few test samples which later confirmed it to be Yellow fever.
NCDC disclosed that in the first half of 2019, about 506 local government areas in all the 36 states including the Federal Capital Territory (FCT), recorded over 2000 cases of the disease. While combatting multiple public health challenges, including the COVID-19 pandemic, the Federal Government, with support of the World Health Organization (WHO), CDC, Gavi, and the Vaccine Alliance, plans to relaunch an accelerated series of mass preventive vaccination campaigns to protect Nigerians against the deadly yellow fever virus.
The earliest yellow fever outbreak in Nigeria was reported in Lagos in 1864, followed by several other outbreaks in 1894, 1905, 1906, 1925 and 1926. In 1969, a major outbreak of yellow fever occurred in Jos, Nigeria, which spread rapidly to many other parts of the country and then resulting to more than 100,000 infected cases. Also, between 1987 and 1996, yellow fever outbreaks affected a total of 120,000 persons in various parts of Nigeria, and no other cases were reported until 2017.
Yellow fever has a vaccine that was introduced in Nigeria in 2004 as one of the routine vaccines to be given to children during immunisation. The government in collaboration with international health agencies made the vaccine available for free in various primary healthcare centres in Nigeria. In spite of government’s early intervention, the country still experiences an outbreak of the disease, due to the low immunization rate in the country. This has been a major contributing factor to the increasing prevalence of the disease in the country.
Nigeria Centre for Disease Control (NCDC) revealed that the regular increase in the occurrence of yellow fever outbreaks is largely dependent on the high rate of unvaccinated people, even when a single vaccination is said to provide immunity for life.
The Center for Disease Control and Prevention (CDCP) also disclosed that the most effective measure to preventing the Yellow Fever infection is to avoid mosquito bites, stressing that this measure should be highly observed. The World Health Organisation (WHO) recommends vaccination as a precaution put in place to fight the deadly virus.
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