Zika Virus epidemic: experts say no cause for alarm in Nigeria

Virologists in Nigeria say that the Zika virus outbreak currently causing a scare in the Americas is yet to be detected from field experiments and preliminary studies in the country.

This comes on the heels of reports suggesting that the Federal Government has embarked on epidemiological tests on mosquitoes to ensure they do not carry the virus.

The World Health Organisation (WHO), says it raised an alarm over the outbreak because of four core reasons; the possible association of infection with birth malformations and neurological syndromes; the potential for further international spread, given the wide geographical distribution of the mosquito vector; the lack of population immunity in newly affected areas, and the absence of vaccines, specific treatments, and rapid diagnostic tests.

There is currently no vaccine available, so the only way to prevent infection is by avoiding mosquito bites. Margaret Chan, a medical doctor who is WHO director-general, said the level of alarm was “extremely high”.

The Zika virus is transmitted to people through the bite of an infected mosquito from the Aedes genus, mainly Aedes aegypti in tropical regions.

This is the same mosquito that transmits dengue, chikungunya and yellow fever.

Nigerians can however heave a sigh of relief, as experts say the country isn’t at risk, yet.

Omotayo Faneye, a doctor of Virology at the College of Medicine, University of Ibadan explains, “although we have the mosquitoes in Nigeria, since they are the ones that transmit dengue and yellow fever, so far, from the surveillance done in the department, we have not seen any of the mosquitoes testing positive as carriers of the virus.”

Faneye explains that human-to-human transmission is limited, as it involves either mosquito bite from an infected person, biting someone else, or the more probable one, which is mother to infant transmission. This she calls congenital defects.

Speaking with BusinessDay, Sunday Omilabu, a professor of virology at the University of Lagos, explains that the main reason for mother to infant transmission is based on the lack of immunity in the fetus to protect itself when the mother gets infected.

Omilabu explains fetal deformities in Nigeria, before the revelation from the Zika outbreak have not been investigated to determine any probable existence of such relationship.

He reiterates that there is a need to expand the scope of investigations to avoid generic assumptions on infant deformity, when these could be narrowed down to specific viral or bacterial causes, such as Zika has revealed.

Omilabu further states that while a number of viruses such as rubella and influenza can cause infant deformity, it now becomes important to take Zika into consideration for an extensive research towards preventing any occurrence in Nigeria.

There are concerns that pregnant women who become infected with Zika virus can transmit the disease to their unborn babies, with serious consequences.

Reports from several countries, most notably Brazil, demonstrate an increase in severe foetal birth defects and poor pregnancy outcomes in babies whose mothers were infected with Zika virus while pregnant.

Colombia, the Dominican Republic, Ecuador, El Salvador, and Jamaica have advised women to postpone getting pregnant until more is known about the risks.

Another possible form of human-to-human transmission is based on a report in 2009, when Brian Foy, a biologist from the Colorado State University, sexually transmitted Zika virus to his wife.

He visited Senegal to study mosquitoes and was bitten on a number of occasions. A few days after returning to the United States, he fell ill with Zika, but not before having had unprotected intercourse with his wife.

She subsequently showed symptoms of Zika infection with extreme sensitivity to light.

Foy is the first person known to have passed on an insect-borne virus to another human by sexual contact.

Zika virus is an emerging mosquito-borne virus that was first identified in Uganda, in 1947, in rhesus monkeys, through a monitoring network of sylvatic yellow fever.

It was subsequently identified in humans in 1952 in Uganda and the United Republic of Tanzania.

Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific.

The Institute for Development Research (IDR) notes a retrospective study on the dengue and chikungunya epidemic that occurred in Libreville, Gabon in 2007 has just shown that zika was also present then.

That was the first time that a zika fever epidemic has been found in Africa, where it originated, and also in an urban setting.

Zika virus disease outbreaks were reported for the first time from the Pacific in 2007 and 2013 (Yap and French Polynesia, respectively), and in 2015 from the Americas (Brazil and Colombia) and Africa (Cape Verde).

In addition, more than 13 countries in the Americas have reported sporadic Zika virus infections, indicating rapid geographic expansion of Zika virus.

IDR also stated on its website, “Knowing the global spread of this insect, these results present a new potential threat to human health around the world.”

Measures to curtail a possible transmission of the virus entail adequate environmental sanitation to eliminate the presence of mosquitoes and their lavas. Mosquitoes and their breeding sites pose a significant risk factor for Zink virus infection as well.

Prevention and control relies on reducing mosquitoes through source reduction (removal and modification of breeding sites) and reducing contact between mosquitoes and people.

WHO also recommends special attention and help should be given to those who may not be able to protect themselves adequately, such as young children; the sick or elderly.

Caleb Ojewale