Disentangling the drivers and host-mediated #global #spread of #H7 #influenza A virus

 

Abstract

Avian influenza H7 viruses pose a significant zoonotic and pandemic threat, yet their evolutionary dynamics, spatial transmission patterns, and host-specific roles remain underexplored. This study integrates phylodynamic and phylogeographic analyses to map global H7 dissemination, quantify host-specific contributions, and identify key ecological and anthropogenic drivers. Epidemiological data show key epidemic waves in Asia during 2013-2014 and 2016-2017, and in Africa in 2023. The Eurasian and American lineages of H7 viruses exhibit transmission with a median velocity of ~661 km/year and ~354 km/year, though spread varies significantly by virus subtype. Anseriformes (~587 km/year) and wild birds (~654 km/year) spread the Eurasian lineage of H7 viruses more rapidly and over greater distances than Galliformes and domestic birds. Geographic distance is negatively associated with the spread of the H7 virus, while temperature and poultry density show positive association. In this work, we identify Asia as an important H7 virus evolutionary epicenter. Anseriformes drives transcontinental spread, whereas Galliformes facilitates local amplification. The dynamics of the H7 virus are shaped by ecological and socioeconomic factors. A One Health approach emphasizing targeted surveillance and global cooperation is essential to mitigate cross-species transmission and future pandemic threats.

Source: 

Link: https://www.nature.com/articles/s41467-026-72718-9

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Rapid #risk #assessment, acute event of potential public health concern: #Diphtheria, #Africa Region (#WHO, March 20 '26)

{Summary)

Risk statement

-- This WHO Rapid Risk Assessment (RRA, v2) aims to assess the risk of diphtheria at the regional level, considering the public health impact, the risk of geographical spread and the risk of insufficient control capacities with available resources. 

-- Diphtheria is a major public health problem in the WHO African Region (AFR) despite significant efforts on immunization in the past decades (e.g. introduction of DTP vaccine in the Expanded Program on Immunisation in 1974). 

-- Between 2000 and 2024, 75 789 diphtheria suspected cases were reported across the Region with an average 3 500 cases per year.    

-- Between the beginning of 2025 and as of 1 March 2026, over 29 000 suspected diphtheria cases with 1 420 deaths (CFR 4.9%) have been reported across these eight countries: Algeria, Chad, Guinea, Mali, Mauritania, Niger, Nigeria and South. 

-- This represents a 67% increase in the number of suspected cases (11 749 additional cases) and a 59.4% increase in the number of deaths (529 additional deaths) reported since the last WHO RRA (v1) conducted in October 2025, Nigeria continues to account for the majority of suspected cases (62.6%) and deaths (66%) in the Region. 

-- Of the 18 130 total confirmed cases (clinically compatible, laboratory-confirmed and epidemiologically linked) across the eight affected countries, 752 (4%) cases were recorded as laboratory-confirmed: Algeria (8), Chad (1), Guinea (48), Mali (66), Mauritania (12), Niger (313), Nigeria (211) and South Africa (93).     

-- Case data trends from 2026 have been difficult to interpret, with extremely delayed case reporting from countries (both to the national and regional levels), and instances of under-reporting also being notified, particularly from humanitarian settings. 

-- However, a lower number of cases are being consistently reported than earlier in the outbreak and thus it appears that new cases continue to decline or plateau, as seen in half of the affected countries (Chad, Mali, Mauritania, and Nigeria).    

-- Since the first WHO RRA (v1) conducted in October 2025, the regional CFR remains around 5%. 

-- While Guinea continues to report among the highest CFRs in the region at 19%, South Africa’s CFR has increased since the last WHO RRA (v1) to 19%.  

-- Children aged 5–14 yrs (57%) and females (63%) are the most affected; where information is available on the vaccination status of cases, most cases are unvaccinated, under-vaccinated, or with unknown vaccination status.   

-- While the overall risk was previously assessed as “HIGH” at the regional level in October 2025, it is now considered “MODERATE” due to:  

• Overall declining trend in number of weekly cases regionally, with country-specific trends also declining in half of the affected countries (Chad, Mali, Mauritania and Nigeria), and only sporadic cases reported from South Africa. 

• Strengthened coordination of public health response through the activation of an Incident Management System (IMS) in most of the affected countries. A joint Regional Office for Africa (AFRO) and WHO headquarters (HQ) IMS structure was activated to support the regional coordination of the response, with high-level ministerial commitment to controlling the outbreaks in the affected countries.  

• Implementation of immunization activities as part of the outbreak response in most of the affected countries. 

• Strengthening of surveillance, case management, community sensitization, through capacity building activities, and the provision of diphtheria antitoxin (DAT), antibiotics, laboratory supplies, etc.  

-- Nonetheless, some challenges continue to prevent the effective containment of these outbreaks:  

• The complex humanitarian situation in many of the affected countries continues to contribute to poor access to immunization and healthcare services for internally displaced persons (IDPs), nomads, miners, and migrants. Unsanitary living conditions (in displacement camps) are also favouring the transmission of diphtheria. These increase the exposure risk of vulnerable groups (particularly women and children) to diseases.   

• Limited laboratory confirmation due to lack of reagents, sample transportation challenges and limited available of laboratory capacity.  

• In most of the affected countries, the annual coverage for routine diphtheria vaccination remains below the national targets thereby contributing to the resurgence of cases and outbreaks.  

• Global scarcity of DAT for the treatment of affected persons. 

• High internal and cross-border movements of susceptible individuals (unvaccinated or not fully vaccinated). 

• Persistent funding challenges across most affected countries exacerbated by the current challenging international funding landscape.  

-- The overall risk at the global level remains ‘’LOW’’ due to: 

- The global risk of diphtheria outbreaks from the ongoing multi-country diphtheria outbreak in the African region is assessed as low, given the existence of routine immunization programs in most countries. 

- Nonetheless, the risk posed by international travel of susceptible populations from the WHO African Region cannot be overlooked, highlighting the need to strengthen risk communication, demand generation and reactive immunisation, as well as the need for enhanced data sharing and surveillance globally. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---diphtheria--african-region-v.2

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#Epidemiology and #genomic features of #MERS #coronavirus in #Africa: a systematic and meta-analysis review

 

Highlights

• 74% pooled MERS-CoV seroprevalence in African dromedaries

• Highest MERS-CoV RNA incidence (15.3%) observed in juvenile dromedaries

• 2.4% pooled MERS-CoV seroprevalence in camel-exposed humans

• African MERS-CoV clade C exhibits unique polymorphisms

• Clade-specific features might explain low MERS-CoV infection rates in Africa

Abstract

Objective

We explored factors contributing to the low human MERS-CoV prevalence in Africa by assessing MERS-CoV epidemiological and genomic features.

Methods

We followed the PRISMA guidelines. We searched for articles on epidemiological and virological MERS-CoV characteristics in humans and camels in Africa until August 2025. We used a generalised linear mixed-effects model to calculate pooled proportions. We identified relevant polymorphisms in African MERS-CoV lineages compared with the prototypic EMC/2012 and contemporary Arabian MERS-CoV (clade B5).

Results

We included 53 articles, with 31 used in the meta-analysis. Kenya, Egypt, and Ethiopia contributed to 66.03% of all included studies. Pooled MERS-CoV RNA positivity in African dromedaries was 6.09%, with juveniles (15.29%) having a higher incidence than adults (4.51%). The pooled MERS-CoV seroprevalence was 73.67%, with adults (80.96%) higher than juveniles (36.02%). In human-focused studies, only nine PCR-confirmed MERS cases were reported, six travel-associated and three autochthonous cases, despite a pooled seroprevalence of 2.4%. Genomic analyses identified MERS-CoV clade C-specific polymorphisms in the Spike and accessory genes with putative phenotypic impact.

Conclusion

We found the highest MERS-CoV RNA positivity in young dromedaries. Elevated MERS-CoV seroprevalence in mainly asymptomatic camel-exposed humans suggests an underestimation of MERS-CoV infections in Africa. The ongoing MERS-CoV evolution emphasises the need for active genomic surveillance to monitor signatures of human adaptation.

Source: 

Link: https://www.ijidonline.com/article/S1201-9712(26)00091-3/fulltext

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#Diphtheria - #Africa Region (#WHO, D.O.N., Nov. 21 '25)

{Excerpt}

Diphtheria is a major public health problem in the WHO African Region despite substantial efforts on immunization activities over the past three decades. 

Between 2000 and 2024, 75 789 suspected diphtheria cases were reported in the Region, with the majority reported from 2023 to 2024, when Algeria, Chad, Gabon, Guinea, Mali, Mauritania, Nigeria, Niger, and South Africa reported a resurgence of diphtheria outbreaks with approximately 57 000 suspected cases and 2 000 deaths (case fatality ratio (CFR) of 3.5%) recorded. 

The countries most affected were Guinea, Nigeria and Niger. 

Most cases reported were in children under fifteen years and female. 

Over 50% of suspected cases were non-vaccinated or with unknown vaccination status. 

In 2025, as of 19 October 2025, over 17 000 suspected diphtheria cases and about 900 deaths with an average CFR of 5.1% have been reported across eight Member States in the African Region; Algeria, Chad, Guinea, Mali, Mauritania, Niger, Nigeria, and South Africa.

Of these suspected cases, 7 886 were confirmed through laboratory testing, epidemiological linkage, or clinical compatibility. 

Laboratory-confirmation has been conducted in 6.8% (n=1181) of the suspected cases. 

Women, children aged between 5 and 18 years and young adults less than 30 are the most affected groups. 

The situation seems to have worsened in Mali, Mauritania and Niger in recent weeks with increasing trends and geographic expansion of the outbreaks reported in these countries. 

In addition, high CFRs (up to 24%) have been reported across all affected countries.   

The overall public health risk posed by the diphtheria event in the African Region is classified as ‘’high’’ due to:

-- Significant risks of further widescale spread:

- The humanitarian profile of some of the affected countries (Chad, Mali, Niger, Nigeria): fragile, conflict-affected and vulnerable settings, with low vaccination coverage often recorded among displaced populations.

- Outbreak hotspots are sometimes located in hard-to-reach areas with security constraints. 

- Crowded, unsanitary living conditions in displacement camps in humanitarian settings.

- Low routine immunization coverage in most affected countries and important heterogeneity in coverage at subnational level in a number of countries - with pockets of under-vaccination leading to outbreaks (e.g. Nigeria, Chad etc.).

- Disruptions caused by the COVID-19 pandemic, causing significant drop of vaccination coverage between the first and the third dose across all affected countries. Although in response to declining immunization coverage, global partners launched The Big Catch-up, a coordinated effort to restore and strengthen immunization services and close immunity gaps, especially for vaccine-preventable diseases such as diphtheria.

- Weak health system capacity in most affected countries (shortage of health professionals, low clinical management capacity, etc.). 

- Shortage of laboratory supplies reported by most affected countries, leading to delays in case reporting and laboratory confirmation. 

- Global shortage of diphtheria anti-toxin (DAT) necessary for the treatment of affected persons. 

- High case fatality ratio observed in many of the affected countries.

- High internal and cross-border movements of susceptible individuals (unvaccinated or not fully vaccinated). 

- Insufficient resources to control the outbreaks across most affected countries.

The overall public health risk posed by the diphtheria event at the global level is classified as ‘’low’’ due to:

-- The global risk of diphtheria outbreaks from the ongoing multi-country diphtheria outbreak in the African Region is assessed as low, given the existence of routine immunization programs in most countries. 

- Nonetheless, the risk posed by international travel of susceptible populations from the African Region cannot be overlooked, highlighting the need to strengthen risk communication and surveillance globally. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---diphtheria--african-region-v.1

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#Mpox in #Africa: What we know and what is still lacking

Abstract

Emerging as a major global health threat, Mpox previously known as Monkeypox has drawn attention due to a worrying surge in cases. This zoonotic disease, native to Central and West Africa, is marked by fever, rash, and lymphadenopathy and is primarily spread through direct contact with infected animals or people and indirectly through contaminated objects. Recent studies have indicated possible sexual transmission, underscoring how human behavior and environmental changes are increasing its prevalence, even though human-to-human transmission is less efficient than that of smallpox. Mpox is endemic in several African countries, and currently, the infection has spread in non-endemic countries, including Rwanda, Uganda, and Kenya. Democratic Republic of Congo is the epicenter of the current Mpox outbreak. From January 1, 2022, to August 6, 2024, sixteen African countries reported Mpox outbreak. Several factors, including population immunity deficiencies and changes to the environment and ecology, have led to the widespread of Mpox in Africa. Challenges such as the fragile healthcare system, limited vaccine availability and access, weak surveillance, and low public awareness poses difficulty in containing the infection in affected countries. Given the potential of Mpox to disrupt several sectors including health systems, which may ultimately reverse progress in achieving the sustainable development goals by 2030. It is imperative for countries, both within and outside Africa, to extend financial aid and human resources to combat the infection effectively.

Source: PLoS Neglected Tropical Diseases, https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0013148

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#Seroprevalence of #H9N2 and #H5 avian #influenza in mixed-species #poultry #farms in Northern #Benin

ABSTRACT

Avian influenza is one of the major threats to poultry and human health in northern Benin, while mixed-species farming systems increase the risks of viral transmission. The present study estimated the seroprevalence of avian influenza subtypes H9N2 and H5 in indigenous chickens and guinea fowls in the Atacora and Donga regions. A total of 300 birds including 191 indigenous chickens and 109 guinea fowls, from six districts were sampled through a cross-sectional survey using systematic random sampling. Hemagglutination inhibition assay was used to detect antibodies, revealing an overall H9N2 seroprevalence of 41%, with 17.5% of samples testing positive for H5. The seroprevalence of H9N2 was notably higher in guinea fowls (51.81% in Atacora and 52% in Donga) compared to chickens (34.95% in Atacora and 34.83% in Donga). H5 antibodies were found only in guinea fowls in Atacora (46.66%). The study also found that farms with both chickens and guinea fowls had a significantly higher odds ratio for H9N2 positivity (OR = 4.25, p < 0.001) compared to chicken-only farms. The results underscore the importance of mixed-species systems in the transmission of avian influenza, suggesting that targeted surveillance and biosecurity measures are essential for controlling the spread of these viruses.

Source: Journal of Immunoassay and Immunochemistry, https://www.tandfonline.com/doi/full/10.1080/15321819.2025.2496480

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Evolving #Epidemiology of #Mpox in #Africa in 2024

Abstract

Background

For decades after the identification of mpox in humans in the Democratic Republic of Congo (DRC) in 1970, the disease was largely confined to the rural areas of Central and West Africa and thus did not garner broad attention. On August 13, 2024, mpox was declared a Public Health Emergency of Continental Security (PHECS) by the Africa Centers for Disease Control and Prevention (Africa CDC), a notice that was followed the next day by a declaration of a Public Health Emergency of International Concern (PHEIC) by the World Health Organization.

Methods

In this study we analyzed all mpox cases and deaths, based on clinical or laboratory diagnosis, that were reported to the Africa CDC from January 1, 2022, to October 30, 2024, to identify temporal variations, geographic distributions, and epidemiologic trends.

Results

From January 1, 2022, to August 18, 2024, a total of 45,652 mpox cases were clinically diagnosed and laboratory-confirmed in 12 African countries. These cases resulted in 1492 deaths (case fatality rate, 3.3%). From 2022 to 2024, weekly laboratory-confirmed mpox cases increased by a factor of 2.8 (from 176 to 489 cases), whereas all weekly reported cases (including those with a clinical diagnosis) increased by a factor of 4.3 (from 669 to 2900 cases). The DRC, which had reported approximately 88% of mpox cases in Africa in 2024, had 19,513 cases before the emergency declaration, with a case fatality rate of 3.1% — a weekly average of 591 cases as compared with 281 in 2023. In 2024, six African countries reported their first imported mpox infections, with Burundi also reporting local transmission.

Conclusions

The high mpox disease burden in Africa, especially in the DRC — with a rising number of cases, high case fatality rate, and high degree of spread to other previously mpox-free African countries — is cause for increased international concern. Case detection, contact tracing, public health measures, and affordable vaccines are needed to implement interventions in the DRC to reduce the risk of global spread of the virus.

Source: New England Journal of Medicine, https://www.nejm.org/doi/full/10.1056/NEJMoa2411368?query=TOC

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Low-Level #Zoonotic #Transmission of Clade C #MERS-CoV in #Africa: Insights from Scoping Review and Cohort Studies in #Hospital and Community Settings

Abstract

Human outbreaks of Middle East respiratory syndrome coronavirus (MERS-CoV) are more common in Middle Eastern and Asian human populations, associated with clades A and B. In Africa, where clade C is dominant in camels, human cases are minimal. We reviewed 16 studies (n = 6198) published across seven African countries between 2012 and 2024 to assess human MERS-CoV cases. We also analyzed data from four cohort studies conducted in camel-keeping communities between 2018 and 2024 involving camel keepers, camel slaughterhouse workers, and hospital patients with acute respiratory illness (ARI). The analysis showed a pooled MERS-CoV prevalence of 2.4% (IQR: 0.6, 11.4) from 16 publications and 1.14% from 4 cohort studies (n = 2353). Symptomatic cases were rarely reported, with most individuals reporting camel contact, and only 12% had travel history to the Middle East. There was one travel-associated reported death, resulting in a mortality rate of 0.013%. The findings suggest a low camel-to-human transmission of clade C MERS-CoV in Africa. Ongoing research focuses on genomic comparisons between clade C and the more virulent clades A and B, alongside the surveillance of viral evolution. This study highlights the need for continuous monitoring but indicates that MERS-CoV clade C currently poses a minimal public health threat in Africa.

Source: Viruses, https://www.mdpi.com/1999-4915/17/1/125

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