Abstract
I
According to the World Health Organization (WHO), the West African island nation of Cabo (Cape) Verde experienced an epidemic of Zika virus involving more than 7,000 persons starting in October 2015, approximately 1 month after the estimated start of the ZIKV epidemic in Colombia. It has not yet been published whether the epidemic in Cabo Verde is due to ZIKV of African lineage or to the Asian lineage causing the panepidemics across Latin America and the Caribbean.
As of March 8, 2016, the WHO reported microcephaly linked to an Asian lineage strain of ZIKV only in French Polynesia in 2014 and in Brazil in 2015-16. 3 Given the normal timeline of pregnancy, a microcephaly epidemic linked to ZIKV could occur in Colombia by May-June 2016 and begin by that time in Cabo Verde. Preparedness for, and early recognition of, a microcephaly epidemic in Cabo Verde would benefit from prospective clinical-epidemiologic studies of pregnant women with ZIKV infection, as have been done in Colombia since December 2015. Such studies in Cabo Verde would be of benefit, whether the ZIKV strain causing their epidemic is proven to be due to African lineage or Asian lineage.
In addition to prospective studies monitoring for microcephaly, surveillance for ZIKV infection itself could be of benefit in Guinea, Liberia, and Sierra Leone, as well as other nations in West Africa such as Guinea-Bissau, which has close travel links with Cabo Verde. The clinical presentation of ZIKV infection, although extremely mild compared with typical Ebola virus disease, could cause initial confusion clinically because both can have fever, muscle and joint pain, red eyes, and rash. If a patient with ZIKV infection were to raise initial concern about a potential Ebola virus infection, then a cascade of unnecessary medical, public health, societal, and political issues could be triggered.
Prospective surveillance for ZIKV in West Africa, including availability of rapid PCR testing, could have at least 3 potential benefits. First, it could facilitate the rapid diagnosis of ZIKV if it is present and allay the cascade of concerns about Ebola. Second, if ZIKV is confirmed, then the need for prospective studies of both ZIKV infections and the spectrum of microcephaly and congenital neurological abnormalities would be clear. Third, in patients with neurological abnormalities, such as Guillain-Barré syndrome (GBS), testing for ZIKV could be performed to assess the GBS-ZIKV link and facilitate an estimate of the preparedness and response level needed for the intensive care that is sometimes required for patients with GBS. Similar preparedness efforts are being made now in parts of Latin America where ZIKA-associated GBS has been reported.
In February 2016, the WHO posted a comprehensive technical report that provided a risk assessment for ZIKV in the WHO African Region. 4 Multiple factors were used to stratify nations by risk. Liberia, Sierra Leone, and Guinea were included in either the high-risk or moderate risk category. Important recommendations were made for serosurveys, in part to help assess the degree of population immunity for both the African and Asian lineage ZIKV, and also for entomological studies. One of the main messages was: “The association of congenital conditions with Zika virus infection, such as microcephaly and Guillain Barré syndrome, still remains coincidental although on-going studies suggest a strong link. Monitoring of these disorders should be implemented as additional indicators of a possible Zika virus outbreak.” 4 (p13)
As the link between ZIKV, microcephaly, and a spectrum of neurological abnormalities has become stronger over the past month, however, this valuable and detailed technical report could be strengthened in practical terms by 3 updates: (1) an explicit strong recommendation for prospective epidemiologic studies to monitor for microcephaly following every known ZIKV outbreak, such as the one that already began in October 2015 in Cabo Verde; (2) explicit discussion of the potential confusion in initial differentiation of the clinical presentations of ZIKV infection and (mild) Ebola virus disease; and (3) making available rapid PCR testing for ZIKV as soon as possible in 2016, especially in Guinea, Sierra Leone, and Liberia, as well as Guinea-Bissau.