Minnesota Department of Health (MDH) Bug Bytes
May 22, 2002
Vol. 3: No. 7
1. It's Spring (sort of), and the Bugs
Despite the cool spring weather, adult deer ticks (Ixodes scapularis) have been actively feeding the past few weeks, and we recently received the first reports of early stage Lyme disease and human granulocytic ehrlichiosis (HGE) for this year. As in past years, we expect the majority of disease transmission to occur over the next 10 weeks. In 2001, 461 Lyme disease cases and 93 HGE cases were reported in Minnesota residents.
Cool weather has slowed down the development of early season mosquitoes. However, the risk of mosquito-transmitted diseases is typically low anyway until July or August, and ends abruptly with the first good frosts in September.
Here are some specifics on the two arboviruses of most concern locally:
1) LaCrosse encephalitis virus (LAC): Cases of LAC occur primarily in children who live in wooded parts of southeastern Minnesota (Iowa border up along the Mississippi River Valley through Carver and Wright Counties just west of Minneapolis). Cases are possible in June, but risk is highest in July and August.
2) West Nile virus (WNV): WNV was detected in birds as close as Madison, Wisconsin and eastern Iowa last fall. Two weeks ago there was a WNV-infected crow reported just west of Chicago, Illinois. Assuming the virus is brought into Minnesota during bird migration in April and May, we would expect several weeks of virus transmission between infected birds and mosquitoes before an epizootic in birds is detectable. Thus, any risk of human WNV encephalitis would be greatest in July through early September. As with other mosquito-transmitted viruses, most people bitten by infected mosquitoes will be asymptomatic or experience mild illness. Elderly people are at greatest risk for severe illness. Our laboratory is prepared to receive and test CSF (by PCR for arboviruses) and serum (EIA for WNV; IFA for LAC, Western equine encephalitis, Eastern equine encephalitis, St. Louis encephalitis).
2. Brucellosis Case
A hospital reported to us a 37-year old Hispanic male who presented to the emergency room with a history of recurrent fevers. His blood culture was positive for Brucella abortus. By history, he had been treated previously in Mexico, and we suspect that his condition was due to a relapse (4-6 week combination therapy is sometimes recommended to avoid relapse).
In consultation with CDC, we recommended that microbiology laboratory workers who had handled the culture be given 3 weeks of doxycycline and rifampin as prophylactic therapy as brucellosis can be an easily acquired laboratory infection. Collection of acute and convalescent sera for testing was also recommended.
Brucellosis is a zoonotic disease of wild and domestic animals. Humans contract the disease by direct contact with infected animals or consuming unpasteurized milk/milk products. Symptoms of acute infection include fever, chills, sweats, headache, and weakness. Chronic brucellosis symptoms include fever, weakness, depression, and anxiety. Brucella is named in honor of British Army Medical Service Surgeon David Bruce who examined the spleens of five fatal case patients from the island of Malta (brucellosis is also known as Malta fever), and who developed culture techniques for the agent in 1887. The U.S. is currently trying to eradicate brucellosis from domestic cattle and bison herds. As of June 30, 2000, 44 states including Minnesota were free of brucellosis with only six known affected herds in the entire U.S. The Animal and Plant Health Inspection Service (APHIS) expects to achieve the goal of national brucellosis eradication from domestic cattle and bison in the very near future.
3. 2001 HIV/AIDS Surveillance
Data Now On-Line
HIV/AIDS surveillance reports have been redesigned and are now available on an annual basis every April (at http://www.health.state.mn.us/
divs/dpc/aids-std/hivsurvrpts.htm). The new versions replace the monthly reports and include slides, tables, and text that describe the HIV/AIDS epidemic in Minnesota. One emerging trend noted is the increased number of HIV infections diagnosed among African-born individuals. Between 1996 and 2001 the annual number of HIV diagnoses increased nearly four-fold in this group to 46 cases. More African-born women were diagnosed with HIV in 2001 than any other female race/ethnicity group.
Thank you for your contributions to the completeness and accuracy of the Minnesota HIV/AIDS Surveillance System. If you have any questions or comments contact Tracy Sides (firstname.lastname@example.org) at 612-676-5461.
4. To C or Not to C? Reporting Hepatitis
May is National Hepatitis Awareness Month. The hepatitis C virus (HCV) antibody test became commercially available in May 1990. Since that time, both chronic and acute HCV infections have been reportable in Minnesota, although historically only the acute cases have been reportable to the CDC. MDH established a hepatitis C database in 1998 to manage the data collection that has been ongoing since the early 1990s. This database allows us to capture "snapshots" of HCV demography and risk factor information. Collected data are proving to be helpful to us in targeting outreach and intervention projects geared toward persons at highest risk of HCV infection and addressing health disparities. We estimate that we don't have complete reporting for all chronic cases statewide. Please send all HCV-positive reports (whether acute or chronic) to us. In the future, CDC will be asking states to report both acute and chronic HCV infections.
5. Syphilis Increase
There has been a recent and unexpected increase in the number of syphilis cases among men who have sex with men (MSM). Statewide, 14 of 21 (67%) syphilis cases have been diagnosed among MSM since January 2002, compared to 2 of 20 (10%) cases during the same time period in 2001. Most of the MSM cases reside in Hennepin County. These cases are occurring among men who range in age from 27 to 62 years. Half of these cases are co-infected with HIV.
The majority of the cases have been diagnosed during the
primary or secondary stage of the disease, suggesting that
these individuals had noticed the initial characteristic symptoms
of sores on or near the genitals or rashes, and did seek medical
care in response to those symptoms. The large proportion of
cases diagnosed during these early stages suggests that these
cases were recently acquired through unprotected sex and there
is a great need to alert their unsuspecting sexual partners
of the need for diagnosis and treatment. The CDC just issued
2002 STD Treatment Guidelines (at http://www.cdc.gov/std)
which call for annual STD screening for sexually active MSM,
and more frequently (every 3-6 months) for MSM reporting anonymous
sex. An image library of STD symptoms including syphilis is
available at http://www.stdptc.uc.edu/PTCs/
6. Antibiogram 2001
The MDH antibiogram is a compilation of antimicrobial susceptibilities of selected pathogens submitted to the Public Health Laboratory during the year 2001. Check it out at http://www.health.state.mn.us/divs/
dpc/ades/pub.htm. Laminated pocket-sized copies perfect for Father's Day or graduation gifts are available on request by contacting us (651-201-5414). Thanks again microbiologists and ICPs for your efforts that have resulted in this tangible useful tool for clinicians.
Bug Bytes is a combined effort of the Infectious Disease Epidemiology, Prevention and Control Division and the Public Health Laboratory Division of MDH. We provide Bug Bytes as a way to say THANK YOU to the infection control professionals, laboratorians, local public health professionals, and health care providers who assist us.
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