Today the World Health Organization's (WHO's) weekly Zika update included a series of Zika "firsts" in several countries, including the first Zika-related birth defects reported in Guatemala.

Also, the CDC released new Zika numbers for the United States, while human trials of a vaccine are set to begin in Brazil.

More Zika spread in Caribbean, Asia

According to the WHO's weekly Zika situation report, the two-island nation of St. Kitts and Nevis is now experiencing Zika transmission, bringing the number of countries or territories with Zika virus to 73.

The number of cases of Zika-related microcephaly also increased this week, as Guatemala reported 17 suspected cases of congenital birth disorders. These are the first such cases reported in the Central American country. Brazil reported 23 more cases of microcephaly, bringing that country's total to 1,911. More cases of microcephaly were also reported in Martinique (2) and the United States (1), bringing the total number of Zika-related microcephaly cases to 2,047 in 21 countries. Microcephaly, a severe congenital malformation of the brain, is one of the most serious outcomes of Zika infection.

Ecuador reported its first cases of suspected Zika-related Guillain-Barre syndrome (GBS), bringing the number of countries with reported GBS to 19. The WHO noted that "neurological complications have been linked only to post-2007 strains of the 'Asian' lineage" Zika virus, but it warned that as new information about different strains of the virus emerges, there could be cases linked to the African strain of the virus, or to strains in Southeast Asia.

To date there have been no neurologic complications associated with Zika cases in Southeast Asia, but the WHO reported increased case counts in Singapore, the Philippines, Malaysia, Vietnam, and Thailand. New sequencing data from two cases of Zika in Malaysia show they are both of the Asian lineage.

Two more US birth defect cases

The Centers for Disease Control and Prevention (CDC) also released its updated Zika numbers today, which includes all cases in the United States and its territories. The CDC reported two more babies born with Zika-related birth defects, bringing that number to 20. The number of pregnancy losses stayed at 5. There are 749 reported cases of Zika in pregnant women in the US states (18 more than last week), and 1,348 in US territories (192 more than last week) as of Sep 15.

The number of travel-related Zika infections in the Unites States is now at 3,314, with 182 more cases reported. In US territories, the number of local infections increased by 2,077 to 17,629, most in Puerto Rico.

Meanwhile, the Florida Department of Health (Florida Health) today reported two more locally acquired Zika cases, bringing that total to 92. One of the cases is tied to the Miami Beach transmission area, and the other is under investigation.

Texas's Tarrant County reported a Zika case in a man who had recently visited Miami. This is the first such case in Tarrant County, and the second case in Texas linked to Florida travel. There are 10 cases across the United States that were transmitted by Florida mosquitoes.

Vaccine studies in humans, monkeys

Finally today, the Brazilian Butantan Institute announced it will begin human trials of a DNA-based Zika vaccine within the next 2 months, according to reports from China.

And two Zika DNA-based vaccines developed by the National Institutes of Health (NIH) proved to be effective in protecting monkeys from the disease after two doses, the NIH said today in a press release. The vaccine uses circular DNA to replicate the shape of the Zika virus.

One of the vaccines is already being testing by human volunteers in three study centers in the United States. If the phase 1 trials are successful, a phase 2 trial in Zika-endemic countries will begin in early 2017.

See also

Sep 22 WHO situation report

Sep 22 CDC Zika case update

Sep 22 CDC update on cases in pregnant women

Sep 22 CDC update on birth defects

Sep 22 Florida Health update

Sep 21 Tarrant County press release

Sep 22 china.org story

Sep 22 NIH news release