Emiliano is one of at least 72 babies born with microcephaly in Angola between February 2017 and May 2018, suspected victims of an emerging Zika outbreak. The cases have gone largely unreported, but an internal World Health Organization report reviewed by Reuters concluded in April that two cases of a potentially dangerous strain of Zika confirmed in early 2017, along with the microcephaly cases identified since then, provided strong evidence of a Zika-linked microcephaly cluster in Angola.

A lack of data and diagnostic testing along with the woefully inadequate Angolan health system has made tracking the outbreak difficult. But new findings from a research team in Portugal suggest that it is the first on the African mainland involving the Asian strain of the disease.

It was the Asian strain that has caused at least 3,762 cases of Zika-related birth defects, including microcephaly, in Brazil since 2015, as well as serious outbreaks in other Latin American countries. Doctors and researchers now fear that it could spread from Angola to other African countries.

“We can’t let our attention down on this. We have to stay vigilant and have a sustained response.”

In an emailed response to questions, Angola’s Ministry of Health said it had reports of 41 cases of Zika and 56 cases of microcephaly since January 2017, when it began gathering data. It was not immediately clear why the figures differed from those in the internal WHO report.

A lack of testing capacity means that many cases of microcephaly go undetected, the ministry added, noting also that microcephaly has many causes, including syphilis and rubella.

The Angolan outbreak comes at a time when world attention has moved on from Zika, and most of the more than $1 billion in U.S. funding allocated to fight the disease has been spent.

“We can’t let our attention down on this,” said Dr. Eve Lackritz, a physician who leads WHO’s Zika task force. “We have to stay vigilant and have a sustained response.”

Brazil’s epidemic prompted WHO to declare a global public health emergency in February 2016 to investigate and ultimately identify the virus as a cause of microcephaly and other birth defects. Lackritz worries about a sense of complacency now that the crisis in Latin America has waned.

“Our work is just starting,” she said in a telephone interview. “We need continued attention and investment to make sure we protect women and babies of the world.”

She said there is still a great need for better diagnostics, greater lab capacity and programs to monitor birth defects.

Only one laboratory in Angola is currently testing for Zika, according to the Health Ministry. To improve the speed and accuracy of diagnoses, it said, laboratories beyond the capital will need to be given testing capacity.

Zika in Africa

First discovered in Uganda's tropical Zika forest in 1947, Zika circulated quietly for years, causing mild, flulike symptoms in parts of Africa and Asia. Over time, the virus diverged into two genetically distinct lines — the African and the Asian lineages — and neither was initially associated with large epidemics.

In late 2007, the Asian strain triggered the first large outbreak of Zika in humans on the island of Yap in Micronesia, infecting 73 percent of residents over age 3. In 2013, an outbreak in French Polynesia was the first linked to microcephaly.

The first lab-confirmed case of the Asian strain in Brazil came in 2015. By 2016, the virus, transmitted by the same mosquito that carries dengue and yellow fever, had spread to nearly all of the states in Brazil, hitting hardest in the tropical northeast. In its wake, thousands of babies were born with small, misshapen heads.

The African strain of Zika has so far not been linked to microcephaly, which is why health officials are so concerned about the Asian strain’s emergence in Angola, a Portuguese-speaking country that serves as a major travel hub for the rest of Africa.

Some health officials are intrigued by the fact that the only confirmed outbreaks of the Asian strain in Africa so far — in Angola on the continent and in Cape Verde, an island nation off the coast of Senegal — have been in countries that, like Brazil, are Portuguese-speaking. They are investigating whether travel ties between Brazil and Portuguese-speaking African nations could have fostered the spread.

In Angola, it has been difficult to directly link microcephaly cases to Zika because of limited access to advanced testing that can confirm the disease even after the acute phase passes.

Four medical professionals who have worked with Angola’s Ministry of Health said there was also little political will to investigate a Zika epidemic on the part of a government already dealing with deadly malaria outbreaks, as well as cholera and the potential threat of Ebola spreading from Democratic Republic of Congo. Speaking on the condition of anonymity due to the sensitivity of the matter, they added that there was concern that an outbreak would require the government to establish costly programs for babies with microcephaly.

The Babies

In Brazil, the epicenter of the largest and most severe Zika outbreak to date, the virus has now virtually disappeared. The high rate of infections two years ago has left much of the population immune, making it harder for the disease to spread.

"The saving grace, if there is any saving grace, is that we have herd immunity," said Dr. Albert Ko, a tropical-disease expert at Yale University. It is not known whether immunity to the African strain also confers immunity to the Asian strain.

Many families affected by the disease still struggle. Jaqueline Vieira de Souza, 28, who lives in the Brazilian state of Pernambuco, describes a grueling daily routine for her son Daniel, born in 2015 with microcephaly: "My day to day is to wake up and take care of him. Therapies and doctors."

Her hopes for Daniel are modest.

“I have no dream of seeing him walk, run," she said. "I only dream that … at least he can eat better, breathe better.”

In Angola, the journey of such mothers is just beginning. There is no public health program to help the children, who need regular physical therapy and other care.

Families are often referred to the Center for Neurosurgery and Treatment for Hydrocephaly in Luanda, even though the center lacks funding to address the problem. Families are expected to pay for consultations, costing between $7 and $21, which is far beyond the means of many in a country where 30 percent of the population lives on less than $1.90 per day.

“The majority come once and never come back,” said physiotherapist Adelina Martins. “They don’t have the means to keep coming.”

On a recent Thursday, Luisa Alberto, 20, waited with her 3-month-old baby to see a doctor with dozens of other mothers sitting in a narrow corridor beneath a portrait of President João Lourenço.

The baby's father has refused to accept him, and Alberto is caring for her first child alone while trying to finish school. The child feeds but is developing slower than his peers.

“It's hard,” Alberto said. “He doesn't play like the other babies.”