News Scan for Aug 28, 2017

New Zika infections
;
Minnesota measles outbreak ends
;
Meningococcal vaccine
;
Jamestown Canyon virus cases

Small Zika increases noted in a few Americas countries

Mexico, Belize, and Costa Rica are among the few Americas countries reporting small increases in Zika virus activity, the Pan American Health Organization (PAHO) said in its Aug 25 epidemiologic update.

In Mexico, the number of Zika cases rose alongside increasing dengue activity between the middle of April through early July. A little more than half of the confirmed cases so far this year are from three states: Nayarid, Tamaulipas, and San Luis Potosi. The number of confirmed cases in those states are higher than reported in 2015 through 2016.

Tamaulipas borders counties in Texas where state health officials recently expanded Zika testing recommendations. It also borders Hildago County, where a local Zika case was recently confirmed.

In Central America, slight increases in Zika cases were reported in Belize and Costa Rica between the middle of May and the middle of July. Elsewhere, sporadic cases continue to the reported from the Caribbean region, with cases declining in Puerto Rico over the last 10 weeks. In South America, cases are decreasing in most countries except for Ecuador, which saw activity increase early in the year and has reported nearly 300 suspected and confirmed cases per week over the past few months.

PAHO said since late 2016, no new countries or territories in the region have confirmed new local Zika spread. One more country—Guyana—joined the list of countries reporting Zika-linked birth defects.
Aug 25 PAHO Zika update

 

Measles outbreak in Minnesota declared over

The Minnesota Department of Health (MDH) late last week declared the end of the state's measles outbreak, which began in April. The last case was reported on Jul 13.

A total of 79 people, mostly unvaccinated children, were eventually diagnosed during the outbreak, making it one of the nation's worst in recent years. It was Minnesota's largest since 1990, when 460 people were infected with the virus, and 3 people died.

Seventy-three of the 79 cases were in children under 10, and 71 were unvaccinated. MDH estimates that 8,000 people were exposed to the virus. A total of 22 people were hospitalized, but there were no deaths during the outbreak.

The vast majority of cases (70) were reported in Hennepin County, where a large Minneapolis Somali-American community lives. That community has high rates of vaccine hesitancy and avoidance due to unfounded fears that the measles, mumps, and rubella (MMR) vaccine causes Autism. According to the MDH, 64 of the 79 cases occurred in Somalis, and the vaccination rate for the MMR vaccine at the start of the outbreak was about 42% among Somali Minnesotan 2-year-olds.

The outbreak was declared over after 42 days (two 21-day incubation periods) passed with no new cases reported.
Aug 25 MDH
press release

 

Study highlights limited herd immunity effect of meningococcal vaccine

Vaccination campaigns at the University of Oregon did not appear to have a large, rapid impact on meningococcal carriage and likely did not provide herd protection after a meningitis outbreak there in 2015, according to a new study led by Centers for Disease Control and Prevention (CDC) experts.

Investigators with the Oregon Meningococcal Carriage Team, comprising experts from the CDC and the Oregon Health Authority, analyzed 4,225 oropharyngeal swabs collected from 3,802 University of Oregon students during two rounds of sampling after the university's seven-case 2015 outbreak of serogroup B meningococcal infection. The prevalence of total meningococcal and serogroup B carriage among sampled students remained stable at 11% to 17% and 1.2% to 2.4%, respectively, during each round.

Neither one to three doses of the MenB-FHbp vaccine nor one to two doses of the MenB-4C vaccine was associated with decreased total or serogroup B carriage prevalence. No student carried the outbreak strain.

The authors conclude, "While few participants completed the full MenB vaccination series, limiting analytic power, these data suggest that MenB-FHbp and MenB-4C do not have a large, rapid impact on meningococcal carriage and are unlikely to provide herd protection in the context of an outbreak response."
Aug 26 J Infect Dis study

 

Maine reports 2 more Jamestown Canyon virus cases

Maine has reported two more infections involving the mosquito-borne Jamestown Canyon virus, bringing the yearly total to three, Maine Public radio reported on Aug 24, citing state epidemiologist Siiri Bennett, MD.

She said it's not clear if the virus is becoming more common or if better testing is finding more cases.

In the middle of July, Maine reported its first case, which sickened an older adult from Kennebec County.

Jamestown Canyon virus is an orthobunyavirus transmitted by different mosquito species. Symptoms include fever, headache, and flulike illness, but severe infections can lead to meningitis or encephalitis.
Aug 24 Maine Public story
Jul 14 CIDRAP News scan "
Adult diagnosed with Jamestown Canyon virus in Maine"

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