Crimean-Congo Hemorrhagic Fever, Herat Province, Afghanistan, 2017

Clinical and Epidemiological Characteristics of 30 Fatal Cases of Crimean-Congo Hemorrhagic Fever in Kabul, Afghanistan: A Retrospective Observational Study

Objective

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic disease associated with a high fatality rate. CCHF is endemic in Afghanistan, and its morbidity and mortality have increased recently but there is limited data about the characteristics of fatal cases. We aimed to report the clinical and epidemiological features of fatal CCHF cases who were admitted to Kabul Referral Infectious Diseases (Antani) Hospital.

Methods

This is a retrospective cross-sectional study. The demographic and presenting clinical and laboratory features of 30 fatal CCHF cases diagnosed by reverse transcription polymerase chain reaction (RT-PCR) or enzyme-linked immunosorbent assay (ELISA) tests were collected from the patients' records between March 2021 and March 2023.

Results

During the study period, a total of 118 laboratory-confirmed CCHF patients were admitted to Kabul Antani Hospital of whom 30 patients (25 males, 5 females) consequently died, indicating a 25.4% case fatality rate (CFR). The age of the fatal cases ranged from 15 to 62 years and their mean age was 36.6 ± 11.7 years. Concerning occupation, the patients were butchers (23.3%), animal dealers (20%), shepherds (16.6%), housewives (16.6%), farmers (10%), student (3.3%), and others (10%). The clinical symptoms of the patients on admission were fever (100%), generalized body pain (100%), fatigue (90%), bleeding (any type) (86.6%), headache (80%), nausea/vomiting (73.3%), and diarrhea (70%). The initial abnormal laboratory findings were leukopenia (80%), leukocytosis (6.6%), anemia (73.3%), and thrombocytopenia (100%), raised hepatic enzymes (ALT & AST) (96.6%) and prolonged prothrombin time/international normalized ratio (PT/INR) (100%).

Conclusion

The hemorrhagic manifestations associated with low platelet and raised PT/INR levels are linked with fatal outcomes. A high index of clinical suspicion is required to recognize the disease at an early stage and to begin the treatment promptly for reducing mortality.

Vaccine efficacy trials for Crimean-Congo haemorrhagic fever: Insights from modelling different epidemiological settings

BACKGROUND

Crimean-Congo haemorrhagic fever (CCHF) is a priority emerging pathogen for which a licensed vaccine is not yet available. We aim to assess the feasibility of conducting phase III vaccine efficacy trials and the role of varying transmission dynamics.

METHODS

We calibrate models of CCHF virus (CCHFV) transmission among livestock and spillover to humans in endemic areas in Afghanistan, Turkey and South Africa. We propose an individual randomised controlled trial targeted to high-risk population, and use the calibrated models to simulate trial cohorts to estimate the minimum necessary number of cases (trial endpoints) to analyse a vaccine with a minimum efficacy of 60%, under different conditions of sample size and follow-up time in the three selected settings.

RESULTS

A mean follow-up of 160,000 person-month (75,000-550,000) would be necessary to accrue the required 150 trial endpoints for a target vaccine efficacy of 60 % and clinically defined endpoint, in a setting like Herat, Afghanistan. For Turkey, the same would be achieved with a mean follow-up of 175,000 person-month (50,000-350,000). The results suggest that for South Africa the low endemic transmission levels will not permit achieving the necessary conditions for conducting this trial within a realistic follow-up time. In the scenario of CCHFV vaccine trial designed to capture infection as opposed to clinical case as a trial endpoint, the required person-months is reduced by 70 % to 80 % in Afghanistan and Turkey, and in South Africa, a trial becomes feasible for a large number of person-months of follow-up (>600,000). Increased expected vaccine efficacy > 60 % will reduce the required number of trial endpoints and thus the sample size and follow-time in phase III trials.

CONCLUSIONS

Underlying endemic transmission levels will play a central role in defining the feasibility of phase III vaccine efficacy trials. Endemic settings in Afghanistan and Turkey offer conditions under which such studies could feasibly be conducted.

Emerging and Re-emerging Infectious Diseases in the WHO Eastern Mediterranean Region, 2001-2018

BACKGROUND

Countries in the World Health Organization (WHO) Eastern Mediterranean Region (EMR) are predisposed to highly contagious, severe and fatal, emerging infectious diseases (EIDs), and re-emerging infectious diseases (RIDs). This paper reviews the epidemiological situation of EIDs and RIDs of global concern in the EMR between 2001 and 2018.

METHODS

To do a narrative review, a complete list of studies in the field was we prepared following a systematic search approach. Studies that were purposively reviewed were identified to summarize the epidemiological situation of each targeted disease. A comprehensive search of all published studies on EIDs and RIDs between 2001 and 2018 was carried out through search engines including Medline, Web of Science, Scopus, Google Scholar, and ScienceDirect.

RESULTS

Leishmaniasis, hepatitis A virus (HAV) and hepatitis E virus (HEV) are reported from all countries in the region. Chikungunya, Crimean Congo hemorrhagic fever (CCHF), dengue fever, and H5N1 have been increasing in number, frequency, and expanding in their geographic distribution. Middle East respiratory syndrome (MERS), which was reported in this region in 2012 is still a public health concern. There are challenges to control cholera, diphtheria, leishmaniasis, measles, and poliomyelitis in some of the countries. Moreover, Alkhurma hemorrhagic fever (AHF), and Rift Valley fever (RVF) are limited to some countries in the region. Also, there is little information about the real situation of the plague, Q fever, and tularemia.

CONCLUSION

EIDs and RIDs are prevalent in most countries in the region and could further spread within the region. It is crucial to improve regional capacities and capabilities in preventing and responding to disease outbreaks with adequate resources and expertise.

Transmission dynamics and vaccination strategies for Crimean-Congo haemorrhagic fever virus in Afghanistan: A modelling study

Background

Crimean-Congo haemorrhagic fever virus (CCHFV) is a highly pathogenic virus for which a safe and effective vaccine is not yet available, despite being considered a priority emerging pathogen. Understanding transmission patterns and the use of potential effective vaccines are central elements of the future plan against this infection.

Methods

We developed a series of models of transmission amongst livestock, and spillover infection into humans. We use real-world human and animal data from a CCHFV endemic area in Afghanistan (Herat) to calibrate our models. We assess the value of environmental drivers as proxy indicators of vector activity, and select the best model using deviance information criteria. Finally we assess the impact of vaccination by simulating campaigns targeted to humans or livestock, and to high-risk subpopulations (i.e, farmers).

Findings

Saturation deficit is the indicator that better explains tick activity trends in Herat. Recent increments in reported CCHFV cases in this area are more likely explained by increased surveillance capacity instead of changes in the background transmission dynamics. Modelling suggests that clinical cases only represent 31% (95% CrI 28%-33%) of total infections in this area. Vaccination campaigns targeting humans would result in a much larger impact than livestock vaccination (266 vs 31 clinical cases averted respectively) and a more efficient option when assessed in courses per case averted (35 vs 431 respectively). Targeted vaccination of farmers is impactful and more efficient, resulting in 19 courses per case averted (95% CrI 7–62) compared to targeting the general population (35 courses 95% CrI 16–107)

Conclusions

CCHFV is endemic in Herat, and transmission cycles are well predicted by environmental drivers like saturation deficit. Vaccinating humans is likely to be more efficient and impactful than animals, and importantly targeted interventions to high risk groups like farmers can offer a more efficient approach to vaccine roll-out.

Crimean-Congo haemorrhagic fever virus (CCHF) is an understudied emerging pathogen and the cause of increasingly frequent outbreaks of haemorrhagic fever in humans in several parts of the world. Here we bring together an important body of work in different aspects of the ecology and epidemiology of CCHF to shed light on its transmission dynamics into humans and the role of environmental drivers. These results show that over the years an endemic pattern of CCHFV transmission has been established within livestock, and the frequency of human cases mirrors the seasonal pattern of livestock transmission. Our analysis further suggests that an important fraction of cases in humans might be subclinical, and the volume of transmission into humans might be much larger than previously thought. We examine the potential impact of vaccination, which suggest that not only human vaccination could be more impactful than animal vaccination, but also that targeted strategies in human high risk groups could be very effective. Our results raise important insights for future vaccine development and important questions on the optimal conditions for conducting Phase III vaccine trials in humans.

Detection of African genotype in Hyalomma tick pools during Crimean Congo hemorrhagic fever outbreak, Rajasthan, India, 2019

Crimean Congo hemorrhagic fever (CCHF) is a zoonotic viral disease presenting with fever and hemorrhagic manifestations in humans. After several outbreaks of CCHF being reported from Gujarat since 2011 till 2019 and from Rajasthan in 2014 and 2015, the present study reports the CCHF outbreak which was recorded from five human cases in three districts Jodhpur, Jaisalmer, and Sirohi of Rajasthan state since August 2019 till November 2019. A high percent of positivity was recorded in livestock animal samples for the CCHFV IgG antibody. CCHF virus (CCHFV) positive human blood samples and Hyalomma tick pool samples were sequenced using next-generation sequencing method. Two different M segment genotypes, encoding glycoprotein precursor, were identified from tick pools in the study: first from Asian and second from African lineage. The L gene (polymerase) and the S gene (nucleocapsid) clustered in the Asian lineage. The present study illustrates the existence of two different CCHFV lineages being circulating within the Hyalomma tick pools in the Rajasthan state, India. We also observed 3.56% amino acid changes between the death and the survived case of CCHFV in the M gene. This report also sets an alarm to enhance human, tick and livestock surveillance in other districts of Rajasthan and nearby states of India. Biosafety measures, barrier nursing along with the availability of personal protective equipment and ribavirin drug will always be a mainstay in preventing nosocomial infection for proper case management.