Presentation on theme: "Beware the Bug that Bites You: Local Transmission of Malaria in Loudoun County Virginia Benita L. Boyer, RN, MS, CIC District Epidemiologist, Loudoun Health."— Presentation transcript:
Beware the Bug that Bites You: Local Transmission of Malaria in Loudoun County Virginia Benita L. Boyer, RN, MS, CIC District Epidemiologist, Loudoun Health District Leesburg, Virginia November 4, 2003
Acknowledgements David Goodfriend & ALL Loudoun County Health Department employees Loudoun Healthcare, Inc. Mobile Health Van, Lab, Linda Belmonte (ICP) Loudoun County Government Services Fairfax County Health Department Gloria Addo-Ayensu, Happy Callaway Infectious Disease Physicians Antonio Pastor, Henry Rhee Clarke Environmental Mosquito Management DCLS Dee Pettit, Mary Mismas, Kelly Felkey VDH Office of Epidemiology John Marr, David Gaines, Diane Woolard, Suzanne Jenkins, Denise Sockwell Hospitals B & C - ICPs Maryland Department of Health and Mental Hygiene Lynn Frank Montgomery County (MD) Health Department Tina Lacey, Yvonne Richards, Carol Garvey Uniformed Services University of Health Sciences CDC Malaria Branch Louise Causer, John MacArthur, Robert Wirtz, Richard Steketee Medical Analysis Systems, Inc. Kirti Davé
Global Impact of Malaria One of the most common parasitic infections in the world Causes about 1 million deaths each year New World species
Malaria in the United States Arrived in the U.S. through colonists/slaves about 600,000 cases decreased to 125,000 cases Zucker. EID. vol 2, no 1, 1996
Malaria in the United States 1950s - Officially eradicated in the U.S. Since then - about 90 cases of domestically acquired malaria Malaria-infected mosquitoes have been found in NONE of these cases There has been one other case in Virginia in the past 50 years Greater than 1,000 cases of imported malaria diagnosed in the U.S. each year
Vectors Transmitted to humans by Anopheline mosquitoes Most common species in the eastern U.S. A quadrimaculatus A. punctipennis Humans are the animal hosts for malaria
Anopheles quadrimaculatus Found in all 48 contiguous states Larvae grow in: permanent fresh water slow streams, ponds, lakes containing surface vegetation Feed at night after dusk/before dawn Rest in hollow trees, underneath buildings Able to overwinter Flight range less than one mile Lay batches of eggs per lifetime 3000 eggs/batch Mosquitoes of North America by Stanley Carpenter and Walter LaCasse Virginia Mosquito Control Association
Disease Control Modern decreases in malaria cases are attributed to: Draining of swamps Access to medical care Availability of quinine and other anti-malarial medications Population movements away from rural areas Mosquito spraying CDC
Malaria in Loudoun County
Loudoun County Suburb of Washington, DC Population about 220,000 with small but rapidly growing Asian and Hispanic populations Bordered by: North - Potomac River and Maryland East - Fairfax County West - West Virginia and Clarke County South - Fauquier and Prince William Counties Dulles International Airport is located on the eastern border of the county
Case #1 August 23, y.o. female from Cascades presented to Health Clinic A with 4-day history of fatigue, fevers, chills, myalgias, sinus pain Dx: Sinus infection Rx: Azithromycin August 27, 2002 Returned to Clinic A with no improvement Fever of o F (39.7°C) Dizziness and Nausea Tachycardia Anemic, with low white blood cell and platelet counts Rx: Levofloxacin Blood smear positive for Plasmodium vivax Treatment: Started on chloroquine (3 days) Switched to primaquine (14 days) Outcome: Complete recovery
Case #2 August 25, y.o. male from Sugarland Run presented to Hospital A ER with 2 weeks of headaches, 4-day history of fever, nausea, vomiting, malaise, nose bleeds Fever of 105°F (40.6°C) Tachycardia, splenomegaly, jaundice Anemic, with low white blood cell and platelet counts Blood smear positive for Plasmodium vivax Treatment: Admitted to hospital Clindamycin Quinine Discontinued due to tinnitus Switched to chloroquine (3 days) Then primaquine (14 days) Outcome: Complete recovery
Case #3 March 16 th, y.o. female from South Riding presented to Health Clinic B with a 4 day history of fatigue, fevers, chills, severe headaches, malaise, arthralgias, myalgias, nausea, vomiting, and mild abdominal pain Prescribed an antibiotic for ‘sinus’ infection March 18 th, 2003 Presented to Hospital C ER - no improvement Fever of 102°F (38.9°C) Anemic, with low white blood cell and platelet counts Blood smear positive for Plasmodium vivax Treatment: Admitted to hospital Doxycycline Quinine sulfate Primaquine (14 days) Outcome: Complete recovery Note: Medical record listed patient’s risk factor for malaria as “lives in Loudoun County”
Comparison of Symptoms Textbook Symptoms: Usually days after infection Episodic high fever recurs every 2-3 days Shaking chills Sweating Headaches, muscle aches, malaise Nausea, vomiting Anemia and jaundice May take up to one year to present Case Symptoms: 4 to 205 days before presentation Fatigue Episodic fever Chills Headaches, muscle aches, malaise Nausea, vomiting Tachycardia Anemia and jaundice Sinus pain
Human Cases – Epidemiology Cases 1 & 2 lived about 1 mile apart in eastern Loudoun County Case 3 lived with a family near case 2 until November 2002 Socialized after dusk in the same area with same group of teens Area is about 7 miles north of Dulles International Airport Selden Island Montgomery County
Epidemiology Several weeks prior to becoming sick: they reported being outside at night within a block of each other received multiple mosquito bites each night Cases 1 & 2 had no history of foreign travel nor of traveling anywhere else together. Case 3 had a half- day trip to Mexico 2 years prior, and travel to Western Europe 4 years before onset Case 3 also fished along the Potomac west of her residence and reported ‘many’ mosquito bites
Sugarland Run Sugarland Run has a large diverse immigrant population Many of the houses had screens that were not intact The area is close to a regional park, which contains multiple potential mosquito breeding grounds
Sugarland Run A review of the neighborhood found multiple mosquito breeding sites
Sugarland Run Residents were educated about the signs and symptoms of malaria by health department staff… … through community town hall meetings and house- to-house instructions prior to adult mosquito spraying.
Traps Mosquito traps placed in the area before spraying caught up to 22 Anopheline mosquitoes per trap Traps placed after spraying for a 1 mile radius around the suspected infection area found 0 to 3 mosquitoes per trap None of the mosquitoes tested positive for malaria Clarke Mosquito
Human Surveillance – Project 1 No additional cases of malaria were found through: A review of patient records at the two local hospitals and local urgent care centers Requests that symptomatic residents be evaluated for malaria by their doctors and reported immediately
Infected Mosquitoes On September 24, 2002 a mosquito trap was placed in the Lansdowne community in response to complaints of nuisance mosquitoes in an area with a population at high risk for complications from West Nile virus
Geography Selden Island Lansdowne is about 6 miles west of Sugarland Run Montgomery County Potomac River
Mosquito Testing Four A. quadrimaculatus and one A. punctipennis mosquitoes were trapped The A. quadrimaculatus pool tested positive for Plasmodium vivax by VecTest™ There was insufficient substrate left for DCLS to confirm the VecTest results by the more traditional PCR testing.
VecTest™ The VecTest malaria assay has been on the market since the beginning of 2002 It was designed for the military to be an accurate, rapid test for P. vivax and P. falciparum antigens It uses a rapid wicking assay of monoclonal antibodies to specific peptide circumsporozoites Medical Analysis Systems, Inc.
Mosquito Testing In response to this finding, additional traps were placed in the general area On September 27, a pool of three A. quadrimaculatus mosquitoes tested positive for malaria in Broad Run
Broad Run Selden Island Both mosquito pools were trapped within ¼ mile of Montgomery County, Maryland. Montgomery County Potomac River
Broad Run In response, Montgomery County enlisted the aide of mosquito surveillance teams from the Uniformed Services University of the Health Sciences (USUHS) USUHS trapped mosquitoes in Montgomery County, MD along the Potomac River on the mainland Selden Island Van Deventer Island
Selden and VanDeventer Islands Selden Island Two mosquito pools on Selden Island tested positive for malaria by PCR, as did one pool on VanDeventer Island Montgomery County Potomac River
Selden Island Selden Island is part of Montgomery County, MD It lies in the Potomac River and: is less than 40 feet from Virginia is accessible only by a bridge from Loudoun County is a popular fishing and recreational area is privately owned and used as a sod farm.
Human Surveillance – Project 2 31 permanent employees worked on Selden Island over the summer Countries of origin: USA: 13 South Africa: 1 Mexico: 17 Central: 15 Hidalgo: 11 Guanquatro: 3 Distrito Federal: 1 Southeast: 1 Veracruz: 1 South: 1 Pachuca: 1 Workers reported being on the island before dawn and after dusk, and had multiple mosquito bites All workers were screened for malaria: Management at Company A’s headquarters in southeast Loudoun County Workers in the sod fields near Dulles Airport
Human Surveillance – Project 2 No employee reported feeling ill Communicable Disease nurse from Montgomery County served as interpreter & administered questionnaire Blood smears drawn on the employees all negative PCR and serology results all negative
Fairfax County An additional mosquito pool tested positive by VecTest™ for malaria near Herndon in Fairfax County This is the only positive A. punctipennis pool and is over 6 miles away both from the Potomac River and where the adolescents were infected The significance of this finding is unknown
Findings August Loudoun County adolescents were symptomatic with P. vivax malaria Between September and October traps along the Potomac River captured mosquitoes positive for P. vivax by VecTest, some confirmed by ELISA, none by PCR The positive mosquito pools were located within 2 miles of each other and at least 4 miles from the infected adolescents February 2003 a ‘malaria summit’ was held with all the main players in attendance to review the findings and discuss testing protocols March 2003 a third domestically-acquired human case was identified in a Loudoun County teenager August 2003 mosquito surveillance along the Potomac found a pool of A. punctipennis positive for P.vivax by VecTest, and confirmed by ELISA and PCR.
What Does This Mean? The most likely explanation is that someone infected with P. vivax abroad spent sufficient time on or near Selden Island to infect the local mosquito population In all previously reported outbreaks, no further cases were reported in subsequent years The VecTest results in 2002 were likely true positives It is likely that mosquitoes infected with malaria have existed along the Potomac River for some time prior to WNV there was no reason to conduct mosquito surveillance There is likely no ongoing propagation of malaria Each year the local mosquito population likely becomes infected by people who contracted malaria abroad The easier it is for people infected with malaria from their original countries to receive treatment, the less likely they will be able to re-introduce the infection into local mosquito populations Social, immigration, and medical access issues Airports receiving planes from endemic areas need to diligently implement disinsection procedures.
Public Health Implications? Strategies to: Quickly detect and treat human cases Remove mosquito breeding grounds Ensure intact window screens Educate people to: Use insect repellent containing DEET Wear light, long, loose clothing