Yesterday in Morbidity and Mortality Weekly Report, investigators describe a deadly outbreak of meningococcal disease primarily in Virginia's Eastern Health Planning Region from 2022 to 2024. The outbreak is notable, as almost 80% of the cases occurred in Black residents, and 63.9% were in an age group (30 to 60 years) not generally considered at increased risk of invasive meningococcal disease (IMD).

From 2012 to 2022, the Eastern Health Planning Region reported an average of only one IMD case annually. In July and August 2022, four patients were identified as being infected with N. meningitidis serogroup Y.

"No common exposures, epidemiologic linkages, or specific risk factors were identified among the four cases," the authors wrote. From June 2022 and March 2024, officials recorded 36 confirmed and 1 probable case of IMD, with 25 in the Eastern Health Planning Region. 

Case-fatality rate near 20%

All patients required hospitalization, and seven died from complications, resulting in a case-fatality rate for this outbreak of 19.4%.

In December 2022, the Virginia Department of Health recommended that local health departments in the Eastern Region offer one dose of MenACWY vaccine, in addition to antimicrobial post-exposure prophylaxis (prevention) to a subset of close case contacts. In August 2023 the recommendation was expanded statewide.

Lack of a well-defined population at risk during this outbreak posed a challenge to implementing vaccination as an outbreak control strategy.

"Lack of a well-defined population at risk during this outbreak posed a challenge to implementing vaccination as an outbreak control strategy," the report concluded. "In this outbreak, selective vaccination of close contacts (in addition to antimicrobial prophylaxis) was recommended in an effort to prevent additional cases among a population presumed to be at risk. Unfortunately, low vaccine acceptance precluded evaluation of the impact of this intervention on outbreak progression."

A systematic review and meta-analysis of studies conducted in 29 African countries found a high burden of shigellosis and concerning levels of antibiotic resistance, researchers reported this week in BMC Infectious Diseases.

The review by researchers at the University of Ghana Medical School included 116 studies examining a total of 99,510 patient samples. The meta-analysis indicated that the overall pooled prevalence of Shigella bacteria across Africa was 5.9%, with regional prevalences of 6.9% in southern Africa, 6.7% in northern Africa, 6.2% in eastern Africa, 4.5% in central Africa, and 4.0% in western Africa. Shigella prevalence was found to be higher in children (6.6%) than in adults (3.6%).

The most prevalent species of Shigella was Shigella flexneri (53.6%), followed by Shigella sonnei (11.5%), Shigella dysenteriae (10.1%), and Shigella boydii (7.7%).

Resistance to ampicillin, trimethoprim-sulfamethoxazole, and chloramphenicol was high (77.8%, 65.1%, and 45.2%, respectively), while resistance to ceftriaxone (8.5%) and ciprofloxacin (10%) was low. 

Conflicts could amplify spread of shigellosis

Shigellosis is a highly infectious gastrointestinal condition that causes an estimated 125 million cases of diarrhea and 160,00 deaths each year. It primarily spreads through the fecal-oral route, often because of inadequate sanitation and consumption of contaminated food or water.

"The estimated prevalence of 5.9% for Shigellosis in the African subregion is a cause for concern, as it indicates a significant risk of exposure to Shigella spp. among the population," the study authors wrote. "This high prevalence is particularly alarming considering the severe nature of the disease and its potential for rapid transmission."

The authors add the high prevalence in Africa is even more worrisome given the number of conflicts in the region, which could cause overcrowding in refugee camps and elevate the risk of Shigella transmission. Given the levels of antibiotic resistance, they call for exploration of alternative treatments for shigellosis, with a particular focus on vaccine development.

This high prevalence is particularly alarming considering the severe nature of the disease and its potential for rapid transmission.

Afghanistan and Pakistan reported more wild poliovirus type 1 (WPV1) cases this week, part of a notable uptick in activity in the two countries where WPV1 is still endemic, the Global Polio Eradication Initiative (GPEI) said in its latest weekly update, as vaccination efforts are poised to resume in Gaza.

Afghanistan reported 1 case in a patient from Hilmand province who had acute flaccid paralysis onset in September, raising the country's total for the year to 23. Pakistan reported 7 more WPV1 cases involving patients with paralysis onsets in August and September, 4 in Balochistan, 2 in Sindh, and 1 in Khyber Pakhtunkhwa. The country has now reported 39 cases in 2024.

Pakistan also reported two attacks on polio vaccination teams this week, one in Upper Orakzai, Khyber Pakhtunkhwa, that killed two policemen who were guarding vaccinators, and a bombing near a police security vehicle in Mastung, Balochistan, that killed nine people, including five children, according to media reports.

Elsewhere, three African countries reported more circulating vaccine-derived poliovirus type 2 (cVDPV2) cases—Chad (3 cases), Niger (1), and Nigeria (5). 

Polio vaccination to resume in Gaza

A third polio vaccination phase is slated to begin in northern Gaza tomorrow, following an October 23 postponement due to lack of access, lack of a humanitarian pause, bombardment, and mass evacuation orders that prevented families from bringing their children for immunization, the World Health Organization and UNICEF said today in a joint statement. 

Health officials have been vaccinating young children following the detection of a cVDPV2 case and positive findings from environmental samples. The groups raised concerns about the scaled-back area covered by the latest humanitarian pause, which will leave children in some towns inaccessible and make it challenging to reach the 90% coverage level needed to ensure the effectiveness of the campaign. 

Ethiopia is experiencing its worst malaria outbreak in 7 years, with more than 7.3 million cases reported since the first of the year, along with 1,157 deaths, the World Health Organization (WHO) said in a notification yesterday. Plasmodium falciparum is responsible for two thirds of the cases.

Owing to favorable ecologic conditions, the western part of the country has faced the biggest disease burden, with the most cases reported in Oromia, Amhara, Southwest, and South Ethiopia Regional State.

Males account for 56% of outpatient cases and 52% of inpatient admissions, which the WHO said may reflect movements of seasonal workers to high-malaria-burden areas. 

Persistent outbreaks, multiple risk factors

Ethiopia's malaria activity has increased over the past 4 years. In previous years, cases have peaked after primary and secondary rainy seasons, but outbreaks have persisted in several regions, including after the secondary season this spring. 

The WHO said the increasing trend and expanding endemic areas are likely related to several factors, including reduced vector-control efforts, protracted conflicts leading to population displacement, and loss of immunity due to reductions in malaria control efforts.

The national risk to Ethiopia is high due to the spread of Anopheles stephensi mosquitoes, which thrive in urban areas, weather anomalies, drought, food insecurity, and poor security, the WHO said. Meanwhile, the risk to the region is moderate for neighboring countries, which are also experiencing outbreaks.

Chronic wasting disease (CWD) has been identified at a Kerr County, Texas, deer farm, the county's first confirmed detection, the Texas Parks and Wildlife Department (TPWD) reported yesterday.

A 3-year-old white-tailed doe tested positive for the fatal prion disease on routine postmortem testing, a finding confirmed by the National Veterinary Services Laboratory (NVSL) in Ames, Iowa. The exact location of the farm wasn't disclosed in the news release.

In December 2023, after a 14-month-old white-tailed buck at the Kerr Wildlife Management Area deer-research facility initially tested positive for CWD, TPWD euthanized all deer in the herd, only to receive a negative test result in January 2024 from the NVSL. No other deer tested positive. TPWD said the decision to cull the herd ended nearly 50 years of white-tailed deer research at the facility.

State's first detection was in 2012

CWD was first found in Texas in 2012 in a wild mule deer in the Hueco Mountains near the state's border with New Mexico. Since then, it has been identified in captive and wild cervids, including white-tailed deer, mule deer, red deer, and elk, TPWD said.

CWD was first found in Texas in 2012 in a wild mule deer in the Hueco Mountains near the state's border with New Mexico.

CWD, a neurologic disease caused by misfolded infectious proteins called prions, affects cervids such as deer, elk, moose, and reindeer. Prions are extremely resilient and can persist in the environment for years. CWD poses an ongoing threat to cervids, because it can spread from animal to animal and through environmental contamination. 

The disease isn't known to infect humans, but officials recommend not eating meat from a sick animal and using precautions when field-dressing or butchering cervids.