Louisiana Research Day Program Book 2025

Case Studies Section 2

Case Studies: Section 2

109 WEST NILE VIRUS CASES: LOUISIANA’S RANKING AMONG HIGH-RISK STATES

110 SEVERE B12 DEFICIENCY PRESENTING AS MICROANGIOPATHIC HEMOLYTIC ANEMIA

Luz Mariana Ramirez Hernandez, Resident Physician 1 ; Mizba Basheer Patel, Resident Physician 1 ; Amanda Schorr, Resident Physician 1 ; Pamraj Sharma, MD 2 ; Richard C Kamm, Jr., MD 3 1 Department of Internal Medicine, St. Francis Medical Center, Monroe, LA; 2 Neurology, St. Francis Medical Center, Monroe, LA; 3 Critical Care Medicine & Pulmonology, St. Francis Medical Center, Monroe, LA

Mark Megaly, MD-PGY 2 ; Deekshitha Manney, MD-PGY 2 ; Harikrishna Bandla, MD, Attending Physician 1 Department of Internal Medicine, SFMC, Monroe, LA; 2 Department of Internal Medicine, SFMC, Monroe, LA; 3 Department of Internal Medicine, SFMC, Monroe, LA

Introduction: West Nile Virus (WNV) was first identified in the U.S. in 1999, reaching Louisiana in 2001 in Jefferson Parish. The Mississippi Delta has historically been a hotspot for arboviral diseases, with WNV outbreaks reflecting patterns from the 1975 St. Louis encephalitis epidemic. This study evaluates the incidence of WNV cases in Louisiana compared to other high-risk U.S. states. Methods: In this retrospective study, we analyzed data from the Centers for Disease Control and Prevention (CDC), the Louisiana Arbovirus Summary Report, and the Mississippi State Department of Health (MSDH) to evaluate the prevalence and incidence of WNV in 2024. We analyzed reported cases of WNV infections throughout the United States, categorizing them into neuroinvasive and non-neuroinvasive types. We calculated case rates by comparing the total number of infections to population estimates based on U.S. Census data. We analyzed the geographic distribution of cases in northern and southern Louisiana parishes and central Mississippi counties. Our statistical analyses included descriptive statistics and

incidence rate calculations to compare WNV prevalence across regions.

parishes: Franklin (7), Ouachita (5), Bossier (2). Meanwhile, 35.3% of cases were in the southern parishes, with 75% of neuroinvasive cases occurring in northern Louisiana and 25% in southern Louisiana. Discussion: Northeastern Louisiana and Mississippi report higher incidences of WNV due to a combination of favorable ecological, climatic, and human factors. Oxbow lakes, freshwater marshes, and flood-prone wetlands, especially those with stagnant water, provide optimal breeding environments for Culex mosquitoes. The Mississippi Delta intersects with the Central and Mississippi flyways, bringing migratory birds such as sparrows and robins, which serve as key reservoirs for WNV and increase transmission risk. Seasonal shifts, including warm temperatures and fluctuating rain patterns, enhance mosquito development and viral activity. Northeastern Louisiana’s agricultural landscape, with standing water, promotes mosquito breeding, while outdoor activities increase exposure to bites. Northeastern Louisiana and Mississippi face unique vulnerabilities compared to other U.S. regions, highlighting the need for increased awareness and preventive measures.

Background: Vitamin B12 deficiency typically presents with symptoms such as fatigue, pallor, glossitis, and neurological manifestations including paresthesias and cognitive disturbances. Laboratory findings often reveal macrocytic anemia, hypersegmented neutrophils, and elevated serum methylmalonic acid and homocysteine levels. Deficiency is seen in approximately 3.6% of all adults aged 19 and older. Rarely, vitamin B12 deficiency can present with microangiopathic hemolytic anemia (MAHA) mimicking thrombotic thrombocytopenic purpura (TTP), with evidence of hemolysis and thrombocytopenia, known as pseudo thrombotic microangiopathy (TMA). This misdiagnosis is particularly common in the context of associated thrombocytopenia, resulting in ineffective and costly treatments like plasma exchange. In this report, we present a case of a young African American female who presented with fatigue and hemolytic anemia. Further investigations revealed severe vitamin B12 deficiency due to pernicious anemia secondary to autoimmune atrophic gastritis. This case highlights the importance of considering vitamin B12

deficiency in the differential diagnosis of microangiopathic hemolytic anemia to avoid unnecessary treatments and ensure appropriate management.

Results: Across the nation, 1,195 cases were reported, including 851 neuroinvasive cases, with reports from 48 states. As of October 31st, 2024, Texas led with 113 cases, followed by California (96), Nebraska (88), New York (93), and Colorado (70). In 2024, Louisiana was positioned among the top 10 most affected states per capita, with 34 cases (1 per 138,090 people), Mississippi 17 (1 per 55,047), and North Dakota 10 (1 per 21,343). In Mississippi, over 50% of cases occurred in central counties: Rankin, Hinds, and Madison, while 34.7% were along the Mississippi River in Bolivar, Washington, and Coahoma counties. Mississippi reports 39 neuroinvasive cases, making up 73.6% of its total 53 cases. Colorado reports 37 neuroinvasive cases, accounting for 52.9% of 70 total cases. Louisiana has reported 25 neuroinvasive cases, accounting for 73.5% of its total 34 cases. This rate is higher than that of neighboring Texas, which has 79 neuroinvasive cases out of 113 total, approximately 69.9%. In Louisiana, 55.9% of cases were reported in the northern

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125 2025 Research Recognition Day