Havana syndrome: a scoping review of the existing literature

Since 2016, numerous American and Canadian diplomats and secret (intelligence) agents in Cuba, China, and other places in the world have experienced an abrupt onset of unusual clinical symptoms including, tinnitus, visual problems, vertigo, and cognitive difficulties, after they encountered strange sounds; this has been called "Havana syndrome" (HS). MEDLINE, Scopus, and Ovid databases from 2016 until 24 September 2021 were systematically searched for the related published manuscripts. The following search strategy was implemented: "Havana syndrome" OR "Neurological Symptoms and US Diplomats". The primary search yielded 120 publications. Only five original studies and 18 non-original articles were considered to be relevant. While these studies provided a constellation of signs and symptoms for HS, none provided a good level of evidence. In conclusion, Havana syndrome is a nonspecific neurological illness with an unidentified causative factor(s), an acute phase of auditory-vestibular symptoms and a chronic phase of nonspecific neurobehavioral symptoms. This syndrome should be considered and investigated as a health concern, and not as a political issue.

diplomats in Havana, Cuba, experiencing vestibular and neurological symptoms

Between 2016 and 2017, several U.S. Diplomats in Havana, Cuba, experienced perplexing vestibular and neurological symptoms attributed to an unknown source. They presented with significant vestibular and headache symptoms similar to individuals who experience vestibular migraine (VM). As such, we hypothesize that VM may be a possible explanation for the Havana cohort's presenting symptoms. To evaluate this hypothesis, we compared symptoms reported by the affected individuals in Havana, Cuba, to symptoms reported by corresponding patients from a tertiary academic neurotology clinic with a chief complaint of vertigo or disequilibrium, who met the International Classification of Headache Disorders criteria for VM. The prevalence of the Havana subjects experiencing various symptomatic domains was compared with the VM cohort, leading to 26 unique domains and statistical comparisons between the cohorts. Of the 26 domains compared between the two cohorts, 18 were not significantly different. This included the two most important components of meeting criteria for VM, namely the co-existence of headache and vestibular symptoms. On regression analysis, the only feature which kept its significant difference between the two cohorts was acute intense head pressure (P = 0.007). The domains with similar occurrence ratios included dizziness, headache, light sensitivity, hearing reduction, and tinnitus. In other words, multiple headache and vestibular symptoms, consistent with VM criteria, were similar between the two cohorts. The considerable similarities across various domains between VM patients and Havana subjects could be due to migraine as a possible common etiology for both groups. We propose VM as a potential etiology for the symptomatology in the U.S. diplomats in Cuba.

New findings of airborne fungal spores in the atmosphere of Havana, Cuba, using aerobiological non-viable methodology

INTRODUCTION

Although airborne fungal diversity in tropical countries is known to be considerable, aerobiological research to-date has identified only a part of the fungal mycobiota that may have an impact both on human health and on crops. Previous studies in Havana city identified only 30 genera and 5 spore types; therefore,new research is required in these latitudes. This study sought to investigate airborne spore levels in Havana, with a view to learning more about local fungal diversity and assessing its influence in quantitative terms.

MATERIAL AND METHODS

A Hirst type volumetric sampler was located on the rooftop of a building 35 meters above ground level, in a busy area of the city. Sampling was carried out continuously (operating 24hours/day), at 10 L per minute during the year 2015. The fungal spores were collected on a Melinex tape coated with a 2% silicone solution. The results were expressed as spores per cubic meter (spores/m³) of air when to referring to daily values, and spores count if referring to annual value.

RESULTS

Fourteen new genera were identified in the course of volumetric sampling: six produce ascospores and eight conidia. Morphobiometric characteristics were noted for all genera, and airborne concentrations were calculated. These genera accounted for 56.4% of relative fungal frequency over the study year.

CONCLUSIONS

Many airbone fungi are primary causes of both respiratory disease and crop damage. These new findings constitute a major contribution to Cuba's aerobiological database.

Molecular epidemiology of tuberculosis in Havana, Cuba, 2009

OBJECTIVES

To estimate the proportion of tuberculosis cases attributable to recent transmission and the risk factors possibly associated with tuberculosis clustering.

METHODS

Population-based study combining information from epidemiological investigation of tuberculosis cases notified to the National Tuberculosis Control Program in Havana, Cuba, in 2009 with the results of genotyping of Mycobacterium tuberculosis isolates with variable number tandem repeat of mycobacterial interspersed repetitive units (MIRU-VNTR) typing.

RESULTS

Of 186 cases, 61 were genotyped: 33 patterns and five clusters with 19, 7, 3, 2 and 2 cases were found. The proportion of cases due to recent transmission was 45% (95% confidence interval 33-58%). Routine contact investigation failed to identify a substantial number of epidemiological links. A history of living in a closed setting was strongly associated with clustering.

CONCLUSIONS

The proportion of cases due to recent transmission in Havana in 2009 is high. The existing control measures in closed settings should be strengthened. A study on a larger number of cases and for a longer time period should be carried out to obtain more precise estimates. Further studies on the utility and cost-effectiveness of the addition of molecular epidemiology techniques to support the progress towards tuberculosis elimination in Cuba, a low-incidence resource-limited setting, are also needed.