If the outbreak in Brazil is not significantly contained by August when the country is set to host the Olympic Games, “there will be legitimate concern that Zika may be spread globally including to mainland Africa”, warns Adamson Muula, professor of epidemiology and public health at the University of Malawi. The outbreak was first reported in Brazil in May 2015.
Africa is largely ill-prepared for large outbreak of the Zika virus, Muula says, because the continent’s laboratories have limited capacity and there would not be enough experts or funds to deal with it.
“There are, however, beacons of hope – such as the National Institute for Communicable Diseases in South Africa, the Uganda Virus Research Institute, and the Centre of Excellence for Genomics of Infectious Diseases in Nigeria that can lead the way,” he says.
Muula believes an overwhelming majority of the continent lacks the infrastructural and human capacity to diagnose the Zika virus disease.
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Lessons from Ebola
He says Africa should learn from the recent Ebola outbreak in West Africa in the sense that unstable health systems are less able to contain infectious disease epidemics.
This month the World Health Organization (WHO) declared the Zika virus outbreak in 30 countries a public health emergency of international concern after more than 4 000 babies in Brazil were born with microcephaly in a period of four months.
Microcephaly is a “rare neurological condition in which an infant’s head is significantly smaller” than those of children of the same age. The condition is usually the result of abnormal brain development in the womb, according to the United States-based research organization, Mayo Clinic.
Although microcephaly can be caused by a number of genetic and environmental factors, there is a “strong association in time and place, between infection with the Zika virus and a rise in detected cases of congenital malformations and neurological complications,” the WHO says.
Experts around the world have welcomed the WHO declaration, saying it will help to streamline research into the Zika outbreak and its impact.
“The declaration is important on multiple fronts,” Muula tells Bhekisisa. “Firstly, it confirms that international health experts are taking the public health threat seriously. Secondly, in response to the declaration, there is often the enhanced provision or allocation of different resources to deal with the threat.”
Deputy director of the National Institute for Communicable Diseases in South Africa, Lucille Blumberg, says the action taken by the WHO “makes the case for improved surveillance, monitoring for microcephaly and other neurological complications, as well as research efforts around vaccines”.
There is currently no vaccine or treatment for Zika virus disease, but Blumberg says that the illness caused by Zika infection is “overwhelmingly mild”.
Symptoms include fever, headache, muscle pain, some inflammation of the eyes and a rash.
“Only one in four infected people will present with any symptoms. It’s a mild illness that lasts about seven days and the majority of people who are infected will get better without treatment,” she says.
Zika virus disease is not fatal, but there have been three reported cases of Guillain-Barre syndrome – a rare neurological condition causing ascending paralyses – where the patients died, according to Blumberg.
The illness is mainly transmitted through mosquito bites. “You won’t get Zika by standing next to somebody, if they cough on you, or by sharing eating utensils,” says Blumberg. “The big concern is the association with the development of microcephaly when women are infected while pregnant.”
A travel advisory has been issued by the Centers for Disease Control in the United States, warning pregnant women to avoid travel to any of the areas currently affected the outbreak. But the WHO says there should be “no restrictions on travel or trade with countries” where Zika transmission has been reported.
“We’re considering monitoring ports, where many vessels, ships and airplanes bring in goods, just to ensure that there are no imported mosquitoes. But we have not seen Zika in Southern Africa; we’ve certainly not seen it in South Africa,” says Blumberg.
“We do have Aedes aegypti mosquitoes [the mosquitoes that transmit the Zika virus] but they appear to be a different subspecies that prefer not to feed on people. We are going to do some further studies and monitor our local Aedes populations.”
Cape Verde off the west coast of Africa is one of nearly 30 countries that have reported an outbreak. But Muula warns that the chances of the outbreak spreading to “mainland Africa” are uncertain.
While many countries on the continent, like South Africa, do have the mosquito species that transmit Zika, an offset in local transmissions “would require that an already infected mosquito come to Africa.
This can be done through international travel by airplanes,” he says. “Sexual transmission of Zika has already been reported in the United States. That would require an individual who is infected elsewhere to come to Africa and then have sex with a susceptible individual.”
Pregnant women most at risk
Blumberg says the biggest challenge when it comes to Zika, is “dealing with microcephaly and managing to provide support for moms who have babies with severe neurological problems. Developing countries may not have those resources.”
Investing more resources into controlling mosquito populations is key to reducing the risks associated with mosquito-borne infections.
According to Blumberg, Aedes mosquitoes breed in little pots of water used to store water in homes in areas that water supplies are not assured.
“Zika is overwhelmingly a mild illness in travellers. Infectious diseases like malaria should not be forgotten,” warns Blumberg. “The Zika virus is transmitted by a day-time biting mosquito, malaria is transmitted by a night-time biting mosquito. Insect repellents are effective for both.”
The ins and outs of the virus and microcephaly
The Zika virus was first identified in a sentinel rhesus macaque, a monkey found in the Zika forest in Uganda, in 1947.
This is where the virus gets its name from, according to Lucille Blumberg, deputy direction of the National Institute for Communicable Diseases in South Africa.
In 1952 Zika was detected in humans in Uganda and Tanzania, the World Health Organization (WHO) says. Previous outbreaks of the virus have taken place in Africa, the Americas, Asia and the Pacific.
According to the WHO, Zika virus disease outbreaks were first reported on the Pacific island of Yap in 2007 and in the South Pacific islands of French Polynesia in 2013.
In 2015 outbreaks were reported in Brazil and Colombia and Cape Verde islands off the coast of Senegal.
To date, says the Pan American Health Organization, cases of Zika virus disease have been reported in 26 countries in the Americas.
The virus is transmitted to people through the bite of an infected female Aedes Aegypti mosquito. “The mosquito needs a blood meal to mature her eggs, and if she’s infected with the Zika virus by feeding on someone who was infected then she can transmit it,” explains Blumberg.
This is the same mosquito that transmits dengue, chikungunya, and yellow fever. The symptoms of these diseases are similar those caused by Zika infection.
These include fever, headache, muscle and joint pain, and a rash, loss of appetite and fatigue, according to the WHO.
Malaria is transmitted by a different mosquito, the anopheles mosquito.
Microcephaly is a neurological disorder that is characterized by a baby having an abnormally small head.
The Mayo Clinic, a United States-based research organization, says that the condition is usually caused by abnormal development of the baby’s brain during pregnancy or “not growing as it should after birth”.
According to the organization, microcephaly is a permanent disability – the only available treatment is therapeutic support that might help enhance a child’s development.
Although microcephaly has been associated with the outbreak of the Zika virus, the Mayo Clinic states that there are many other causes of the condition. These include:
- Craniosynostosis – the premature fusing of the joints (sutures) between the bony plates that form an infant’s skull keeps the brain from growing;
- Chromosomal abnormalities – Down syndrome and other conditions may result in microcephaly;
- Decreased oxygen to the fetal brain (cerebral anoxia) – certain complications of pregnancy or delivery can impair oxygen delivery to the fetal brain;
- Infections of the fetus during pregnancy – these include toxoplasmosis, cytomegalovirus, German measles (rubella) and chickenpox (varicella);
- Exposure to drugs, alcohol or certain toxic chemicals in the womb – any of these put one’s baby at risk of brain abnormalities;
- Severe malnutrition – not getting adequate nutrition during pregnancy can affect your baby’s development; and
- Uncontrolled phenylketonuria, also known as PKU, in the mother. PKU is a birth defect that hampers the body’s ability to break down the amino acid phenylalanine.