Nigeria at Risk of Zika Virus

With the recent alarm raised by the Nigerian Centre for Disease Control that the Zika virus vector is widely circulating in Nigeria, experts are of the opinion that the government must step up measures against the deadly disease. Martins Ifijeh writes

When Brazil, in June last year experienced an outbreak of Zika virus, a relatively unknown pathogen, not many people referred to it as a public health challenge requiring utmost priority, until it took a new turn and was becoming deadly, forcing the World Health Organisation (WHO) in February 1 this year, to declare it an international health emergency, requiring new and urgent tool to eradicate.

But as Nigerians continue to see it as American and Asian health challenge, recent development suggests Nigeria and other malaria endemic nations are at risk of the deadly virus since its transmitter, the Aedes mosquitois a common strain of the mosquito family known to exist in Nigeria and other countries battling with malaria.

In fact, in a more direct statement by the Director General and Chief Executive Officer of the Nigerian Centre for Disease Control (NCDC), Dr. Chikwe Ihekweazu, Zika virus is already widely circulating in the country. Shockingly, he said there was the absence of continued surveillance or periodic national surveys, with the epidemiology of the virus still poorly understood in the country.

Though an uncommon disease, it is not strange to Nigeria and Africa at large. In 1960, the country experienced the first human case of the virus, according to WHO records; that is 27 years after it was first documented in monkeys in Uganda, an East African country, known to be a breeding region for mosquitoes, just like Nigeria.

But the world did not take the 76 years old virus seriously because its outbreaks were sporadic and tiny, and the disease seemed to do little harm to humans, until recently with its recent manifestation in South America and Asia, starting with birth deformities in newborn, among other clinical features.

The virus is a disease transmitted by the bite of an infected Aedesaegypti mosquito – the same mosquito strain that causes dengue and other tropical diseases. Experts described it as a strain with white markings on its legs and a marking in the form of a lyre on the upper surface of the thorax. The average wing length of female Aedesaegypti mosquitoes varies greatly between
1.67– 3.83 mm in Peruvian habitat.

According to Ihekweazu, “Previous evidence of detection of Zika virus in man, and antibodies to Zika virus in Nigerian populations, together with the presence of the vectors indicate that the virus is widely circulated in Nigeria, adding that the majority of those infected with the virus remain asymptomatic and for those who develop symptoms, such as, fever, rash, conjunctivitis, headaches, muscle and joint pains, it typically start three to six days after infection. “The virus might stay in the body for weeks following infection,” he said.

He noted that current epidemiology of Zika in Nigeria has not been well documented or understood due to paucity of recent data, adding that the virus shares a similar vector, the Aedes (Steogmyia) mosquitoes, also responsible for other flavivirus infections recorded in
the country, such as yellow fever and dengue.

“The environmental and human behavioural risk factors in areas with reported Zika outbreaks were similar to those found in Nigeria and would thus favour the circulation of Zika virus,” Ihekweazu said.

“Possible cross-reaction with other endemic flaviviruses like yellow fever and dengue; genetic host factors protecting against infection or disease; low vector competence and transmission efficiency; lack of diagnostic testing; and the absence of systematic surveillance are potential limitations to detect on-going transmission of Zika in the country.”

Concluding the CEO said all countries with presence of Aedes (Steogmyia) albopictus and Aedes (Steogmyia) aegypti mosquitoes are at risk of sustained transmission and human activity aids the spread of the virus to locations far beyond the normal range for the vector.

He explained that in the light of the review, NCDC plans to initiate surveillance to understand and monitor the epidemiology of the virus in the country for appropriate interventions.

Reacting to the revelation that Nigeria was greatly at risk of the scourge, a virologist, Dr. Alabi Shogunle, said the devastation being presently experienced in Brazil and neigbouring countries should be enough to push Nigeria to guide jealously against the virus in the country.

While explaining that prevention was possible, he called on Nigerians to avoid mosquito bites through keeping their environments free from logged waters, adding that since the country was a tropical region where mosquitoes were common, there was need for the use of insecticide treated nets in all homes. “This will be about a two way benefit; preventing Zika virus, as well as malaria,” which he stressed were products of mosquito bites.

He said Zika virus could be passed through sexual intercourse, hence, “the consequences of unfaithfulness cannot be limited to HIV and other sexually transmitted diseases, but also to Zika virus. Those who can’t stick to one faithful partner should always use condon or abstain,” he added.

While warning that those going to Zika virus endemic countries should be cautious of activities that could put them at risk of the disease, he said the country should ensure precautionary measures activated during the Ebola virus outbreak in the country were put back in place.

On the symptoms, he said even though it is largely assymptomatic, in the rare case of presentation, symptoms include fever, joint pain, rash, conjunctivitis, muscle pain, headache, adding that the amount of time the symptoms last depends on the severity of the infection. “Traditionally, when symptoms like these are noticed, it is important to see a doctor, who will diagnose and treat appropriately,” he said.

“People usually don’t get sick enough to go to the hospital, and they very rarely die of Zika. For this reason, many people might not realise they have been infected. Symptoms of Zika are similar to other viruses spread through mosquito bites, like dengue and chikungunya.”

Recall that so far, especially in Latin America and other parts of the Americas, the disease has affected over three million people, with Brazil worse hit by the scourge in the latest outbreak, which has taken a more surprising shape; causing thousands of birth defects.

Over one million people have been infected in Brazil with some of them coming down with symptoms, which includes conjunctivitis, low-grade fever between 37.8°C and 38.5°C, arthralgia, notably of small joints of hands and feet, with possible swollen joints, muscle pain, headache, retro-ocular headaches, cutaneous maculopapular rash, post-infection asthenia which seems to be frequent.

In a more drastic twist, experts believed the infection has caused the malformation of newborns in affected countries, with some born with little or no foreheads.

Earlier in February, the Minister of Health, Prof. Isaac Adewole, urged Nigerians to protect themselves against the virus by using mosquito nets, noting that since the virus was spread through a particular type of mosquito, it was necessary for Nigerians to adhere to the various measures put on ground to prevent mosquito bites.

He also called on Nigerians to remain calm, be vigilant and report any suspected case of an acute febrile illness in pregnant women, in particular, to any nearest health facility.

Adewole who made this disclosure at a press briefing in Abuja, where he explained that the mosquitoes were active and flying, adding that they bite during the day and early morning.

He said: “Nigerian scientists working in Western Nigeria in 1954 discovered Zika virus in Nigeria. Further studies in the years 1975 to 1979 showed that 40 per cent of Nigeria adults and 25 per cent of Nigerian children have antibodies to Zika virus, meaning they are protected against this virus.

“Despite the fact that some Nigerians are immune to the Zika virus infection as demonstrated by previous studies, it is important and advisable that Nigerians should be careful and protect themselves from mosquito bites. “There is no vaccine for Zika virus, and no cure other than rest, plenty of fluids and perhaps over-the-counter medication to reduce fevers, aches and pains as previously mentioned.

“This, therefore, means that prevention is the most effective means of preventing transmission.
I advise all Nigerians, particularly pregnant women, to avoid travelling to countries infected by this virus in these periods. If however, you are to visit any country where Zika virus is now being actively transmitted, you are advised to protect yourselves from mosquito bites.”

He advised pregnant women considering travel to affected areas to consult their healthcare
provider prior to travel and after return, adding that they should also practice personal and household steps to prevent mosquito, including putting mosquito repellant on their clothes and skin, wear long sleeves and pants, and sleep underneath mosquito nets at night, where possible.”