Research and analysis

Infectious disease surveillance and monitoring for animal and human health: summary October 2023

Updated 25 April 2024

Interpreting this report

The UK Health Security Agency’s (UKHSA) Emerging Infections and Zoonoses (EIZ) team uses an integrated horizon scanning approach, which combines information on both human and animal health, to identify and assess outbreaks and incidents of new and emerging infectious diseases globally. For further information about the EIZ team’s horizon scanning process, please see our Epidemic intelligence activities.

This summary provides an overview of incidents (new and updated) of public health significance, which are under close monitoring. The incidents are divided into 2 sections: notable incidents of public health significance and other incidents of interest. For each notable incident of public health significance, an incident assessment is provided, based on the EIZ team’s interpretation of the available information.

The report also includes a section that focuses on novel pathogens and diseases and a final publications of interest section, which contains new publications relevant to emerging infections.

For more information, or to sign up to the distribution list to receive an email alert when new reports are published, please contact epiintel@ukhsa.gov.uk

Notable incidents of public health significance

Summary of incidents

Disease or infection	Location	New or update since the last report
Avian influenza A(H5N1)	Cambodia	New
Locally acquired dengue	Europe	Update
Nipah virus infection	India	Update

Avian influenza A(H5N1) – Cambodia

Event summary

In October 2023, the Cambodian Ministry of Health (MoH) reported 2 confirmed fatal cases of avian influenza A(H5N1). The first case, reported on 7 October 2023, was a 50-year-old male from Romeas Haek District, Svay Rieng Province. The second fatal case was reported on 9 October 2023, in a 2-year-old female from Kamchay Mear District, in the neighbouring Prey Veng Province. Both cases had exposure to dead poultry in and around their homes prior to illness. There is no evidence suggesting the cases were epidemiologically linked, and no further cases were identified during contact follow-up.

On 12 October 2023, the United States Centers for Disease Control and Prevention reported that genetic sequencing of patient specimens by the Institut Pasteur du Cambodge and the Cambodian National Institute of Public Health revealed the virus implicated in these cases belonged to the 2.3.2.1c clade; similar to viruses that have been circulating in the region over the past decade. Sporadic human infections with this clade have previously been reported, including 2 cases from Cambodia in February 2023.

So far in 2023, 4 confirmed cases of avian influenza A(H5N1) clade 2.3.2.1c (including 3 deaths) have been reported in Cambodia. These were the first human cases of avian influenza A(H5N1) reported in Cambodia since 2014. Cambodia has reported 59 human infections of avian influenza A(H5N1), including 39 deaths, since 2005.

Incident assessment

Globally, from 1 January 2003 to 1 November 2023, 880 cases of human infection with avian influenza A(H5N1) virus were reported from 23 countries. Of these, 460 were fatal (case fatality rate (CFR) of 52%). Whenever avian influenza viruses are circulating in poultry, there is a risk for sporadic infection or small clusters of human cases due to exposure to infected poultry or contaminated environments. However, avian influenza A(H5N1) human cases are sporadic, and sustained human-to-human transmission has never been observed.

5 avian influenza A(H5N1) cases have been reported in the UK to date. Currently, the risk of avian influenza A(H5N1) infection to UK residents is considered very low. The risk of avian influenza A(H5N1) infection to UK residents who are travelling to affected areas is very low but may be higher for those with exposure to potentially infected poultry and/or their contaminated environments. For further information, see UKHSA’s risk assessment of avian influenza A(H5N1).

Locally acquired dengue – Europe

Event summary

Between 4 August and 17 October 2023, France reported 35 autochthonous cases of dengue in 4 regions, including Provence-Alpes-Côte d’Azur (14 cases), Occitania (18 cases), Auvergne Rhône-Alpes (2 cases) and Île-de-France (1 case). The case in Limeil-Brévannes, Île-de-France region, is the most northerly record of vector-borne transmission in Europe to date. Santé Publique France, local and national health authorities will continue to monitor the situation closely until the end of the dengue transmission season in November. During 2022, France reported 65 autochthonous cases of dengue; which was the highest number of locally acquired cases reported within Europe that year.

As of 30 October 2023, Italy’s Higher Institute of Health have reported 68 autochthonous dengue cases in Italy so far in 2023 (Figure 1). In response to these cases, the Italian public health authorities implemented control measures including case finding, vector control activities and risk communication to healthcare providers and the general public. Since the mosquito vector, Aedes albopictus, is established in most of Europe, locally acquired cases of dengue are not unexpected within the southern European countries, particularly during the summer months when conditions are favourable for the vector. Autochthonous dengue cases were reported in Italy for the first time in 2020, in the Veneto region.

Figure 1. Locally acquired and imported dengue case numbers by reporting month and year in Italy, as of 30 October 2023.

Adapted from Italy’s Higher Institute of Health. Accessed: 31 October 2023.

On 27 October 2023, Catalonia’s Public Health Agency reported 3 autochthonous dengue cases in Catalonia, Spain, during 2023; the first locally acquired infections reported in 4 years. At the beginning of August 2023, the first case was detected in the Tarragona area. Another case was reported in the Maresme area at the beginning of October 2023. On 20 October 2023, a third suspected case of dengue was reported, also in the Maresme area, which was subsequently laboratory confirmed. Of the 3 cases, 2 required hospital admission and were later discharged.

Incident assessment

The geographic distribution of dengue and its mosquito vectors has changed in recent years, with locally acquired cases being reported from European countries including France, Italy and Spain during 2023. Moving into the Winter months, conditions for the competent vectors become less favourable and thus a reduction in dengue transmission is expected.

Transmission of dengue in the UK is contingent on 2 factors:

1. The presence of infected humans. 2. The presence of competent mosquito vectors.

There is no current evidence of local transmission of dengue in the UK. All human cases reported in the UK have been acquired as a result of travelling to dengue affected areas, the majority to South and South East Asia, the Caribbean, Eastern Africa and South and Central America. Whilst sporadic incursions of competent vectors have been detected through active surveillance programmes in the UK, there is no current evidence of established populations of these vectors required for dengue transmission. Thus, the probability and impact of dengue on the UK population would currently be considered very low.

Nipah virus disease – India

Event summary

Between 12 and 15 September 2023, 6 laboratory confirmed cases of Nipah virus infection, including 2 deaths, were reported by the Government of Kerala. All confirmed cases were epidemiologically linked and were reported within the Kozhikode District of Kerala. As of 30 October 2023, Kerala’s Government reported that there had been no new confirmed cases since the 15 September 2023. The government’s response measures included declaring containment zones in 9 villages in the Kozhikode District with movement restrictions, social distancing and mandatory mask-wearing in public spaces. Additionally, the government restricted major public events in the district until 1 October 2023. Alerts were issued to neighbouring districts and states for enhanced surveillance. On 19 October 2023, media reported that the Indian Council for Medical Research confirmed the presence of Nipah virus antibodies in 12 bat samples collected from Maruthonkara. Health officials concluded that bats were likely the source of the Nipah virus outbreak in Kozhikode District.

Incident assessment

The current outbreak is the third outbreak in Kozhikode District and fourth in the state of Kerala. The cases associated with this outbreak are epidemiologically linked and localized to one district. Public health teams and health care workers in Kozhikode District had prior experience in managing outbreaks of Nipah virus infection, and they promptly established response measures to limit the outbreak’s spread.

To date, there have been no reported cases of Nipah virus in the UK. While severe disease in a case is possible, transmission within the wider UK population is highly unlikely as there are established processes for the isolation and contact management of high consequence infectious diseases (HCID) cases. There are a range of robust public health, clinical, infection prevention and control measures available for HCID, which can be adapted for use as necessary.

Other incidents of interest

Summary of other incidents

Disease/infection	Location
Anthrax	multi-country
Cholera	multi-country
Crimean-Congo haemorrhagic fever	multi-country
Dengue	multi-country
Diphtheria	multi-country
Hantavirus	multi-country
Lassa fever	Nigeria Liberia
Lymphatic filariasis	Lao People’s Democratic Republic
Mpox	multi-country
Plague	Madagascar
Rabies	Peru
Rubella	Democratic People’s Republic of Korea
Measles	multi-country
Tick-borne encephalitis	Russia
Visceral leishmaniasis	Bangladesh
West Nile virus	United States of America

Anthrax

In Kazakhstan, on 26 October 2023, media reported that 3 cases of anthrax cases were hospitalised and 2 more were under supervision. A total of 30 contacts were identified. On 31 October 2023, media reported that 37 anthrax cases and one death had been reported in Kazakhstan since the start of 2023. All reported cases were the cutaneous form of anthrax and there have been 33 recoveries amongst the cases.

On 26 October 2023, the Uganda MoH reported an outbreak of anthrax in Kween district, eastern Uganda. The index case was a 42-year-old labourer who presented with skin lesions. As of 28 October 2023, 5 cases (3 confirmed; 2 suspected) and no deaths have been reported. Anthrax is endemic in Uganda, with outbreaks occurring sporadically in different subregions of the country.

Between 1 January and the end of October 2023, the Zambian MoH reported 335 anthrax cases and 4 deaths nationally. Sinazongwe within the Southern Province reported the highest number of cases (242 cases including 2 deaths). Anthrax is endemic in Zambia. In response to the ongoing incident, the MoH implemented a range of one health approaches to contain and prevent the spread of anthrax in the country.

In Zimbabwe, as of 15 October 2023, 369 suspected cases have been reported from one of 10 provinces. The current outbreak started on 12 February 2023, in Chegutu town, Mashonaland, West Province. In response to the ongoing incident, the MoH deployed rapid response teams to conduct enhanced surveillance, environmental sanitation, safe burial of carcasses, risk communication and animal vaccination.

Cholera

Since the beginning of 2023, 29 countries have reported cholera cases, globally. The overall capacity to respond to multiple and simultaneous outbreaks remains strained due to a global lack of resources, including shortages of the oral cholera vaccine and cholera supplies, as well as overstretched public health and medical personnel. The World Health Organization (WHO) continues to assess the risk of cholera at global level as very high.

The WHO African Region remains the most affected region. 18 countries have reported cholera cases since the beginning of 2023. As of 28 October 2023, 197,764 cases (86,350 confirmed; 111,414 suspected) and 3,105 deaths (CFR of 1.6%) of cholera have been reported. The most affected countries include:

• Malawi (42,971 cases; 1,261 deaths)

• Democratic Republic of the Congo (DRC) (36,084 cases; 303 deaths)

• Mozambique (35,145 cases; 147 deaths)

• Ethiopia (24,559 cases; 321 deaths)

• Cameroon (20,842 cases; 491 deaths)

• Somalia (14,407 cases; 38 deaths)

In Sudan, a cholera outbreak was declared in Gedaref state on 26 September 2023, following confirmation that 4 stool samples from suspected cases contained Vibrio cholerae. As of 28 October 2023, 1,617 cases (1,535 suspected and 82 confirmed cases) and 64 deaths (CFR of 3.9%) have been reported. According to the United Nations Office for the Coordination of Humanitarian Affairs, 3.1 million people in Sudan are at risk of cholera in 8 states between July and December 2023.

In Tanzania, on 27 October 2023, an outbreak of cholera was reported in 6 regions of the country. The outbreak was confirmed after one of 3 samples tested positive for Vibrio cholerae at the Simuyu Regional Referral hospital. This is the second outbreak of cholera reported in Tanzania in 2023 after the first outbreak was reported in April 2023. As of 28 October 2023, a total of 548 cases including 14 deaths (CFR of 2.6%) were reported from 11 districts of Mara, Kigoma, Arusha, Kilimanjaro, and Singida regions.

In Zimbabwe, as of 29 October 2023, 5,964 suspected and 1,055 confirmed cases of cholera have been reported nationally so far in 2023. There have also been 5,696 recoveries representing a recovery rate of 97%.

Other notable outbreaks have been reported from the WHO Eastern Mediterranean region, including Afghanistan (185,446 cases; 86 deaths), Syria (147,290 cases; 4 deaths) and Somalia (14,191 cases; 38 deaths). Several factors have likely contributed to the resurgence of cholera in the region, including climate change, conflict and political instability, weak health systems, increased population movement, poor water and sanitation infrastructure and low awareness among the public.

Crimean-Congo haemorrhagic fever (CCHF)

CCHF is endemic in Africa, the Balkans, the Middle East and western and south-central Asia. The WHO Eastern Mediterranean Region remains the most affected region, reporting the highest number of cases.

As of 28 October 2023, 1,190 suspected CCHF cases and 110 deaths (CFR of 9.2%) have been reported in Afghanistan. The CCHF-associated deaths were reported from 15 provinces, more than half of which were from Kabul (48, 45.7%) and Balkh (15, 14.3%) provinces.

On 9 October 2023, media reported that the Iraq MoH have registered 545 confirmed cases of CCHF, including 70 deaths, since the beginning of 2023. The highest number of cases have been reported from Dhi Qar (132 cases, 13 deaths), Basra (81 cases, 11 deaths) and Baghdad Al Rusafa (53 cases; 11 deaths) governorates. On 24 October 2023, media reported that 18 CCHF cases, including 4 deaths, have been registered in Diyala Province since the start of 2023.

On 5 October 2023, 6 cases of CCHF were reported in Rospotrebnadzor, Russia.

On 6 October 2023, media reported a case of CCHF in Quetta, Pakistan. The case was hospitalized on 5 October 2023 and presented with symptoms typical of haemorrhagic fever. On 14 October 2023, media reported a case of CCHF in a patient admitted to Quetta hospital. The case is a male resident of Kuchlak and was diagnosed with CCHF following a positive test.

On 24 October 2023, Santé Publique France reported the detection of the CCHF virus in Hyalomma marginatum ticks collected from cattle on 6 October 2023, in the Pyrénées-Orientales, France. The detection was identified as part of a study by the Centre for International Cooperation in Agricultural Research for Development to detect the presence of CCHF in France. Previously, antibodies to CCHF virus were detected in domestic and wild ungulates, on the French island of Corsica.

Dengue

Between 1 January and 30 October 2023, the Government of Bangladesh reported 271,175 dengue cases, including 1,348 associated deaths (CFR of 0.5%), with 99,169 cases (37%), including 810 deaths (60%) reported from Dhaka City.

On 20 October 2023, the Pasadena Public Health Department reported the first confirmed autochthonous case of dengue in California. In response to the incident, field teams were deployed to Pasadena neighbourhood to offer information for mosquito preventive measures. An additional 47 autochthonous cases of dengue have been reported in the United States of America in 2023, from Florida (46 cases) and Texas (1 case). 

On 30 October 2023, media reported the first ever case of dengue vertical transmission in the Dominican Republic. In epidemiological week 42, 15,606 cases and 16 deaths (CFR of 0.1%) were reported in the country.

Within the African Region, 12 countries have reported dengue cases since the start of 2023. As of 28 October 2023, a total of 89,411 cases (20,390 confirmed; 69,021 suspected) and 158 deaths (CFR of 0.2%) have been reported. The most affected countries include:

• Burkina Faso (73,596 cases; 133 deaths)

• Ethiopia (10,233 cases; 4 deaths)

• Sudan (1,664 cases; 7 deaths)

• Sao Tome and Principe (1,227 cases; 11 deaths)

• Chad (960 cases; 1 deaths)

In Chad, on 15 August 2023, the Ministry of Public Health and Prevention officially declared the first ever outbreak of dengue in Abéché health district, Ouaddaï Province. WHO states that the movement of returning Sudanese refugees and Chadian nationals has the potential to spread the outbreak to new provinces and across the border. WHO assesses the risk posed by this outbreak as high at the national level, moderate at regional level and low at global level.

Diphtheria

Diphtheria is re-emerging in 4 African Union Member States: Algeria, Guinea, Niger, and Nigeria. 14,587 cases (with a CFR of 4.1%) had been documented as of 9 October 2023, in these Member States. More than 90% of the cases reported were in Nigeria. According to the Africa CDC, more than 60% of recorded cases of diphtheria in Africa are less than 15 years old, and more than 65% lack prior immunization.

Hantavirus

On 24 October 2023, media reported one confirmed hantavirus case in a 53-year-old man in Neuquén, Argentina.

In Bolivia, on 5 October 2023, media reported that 18 cases of hantavirus were registered in 4 departments: La paz (7 cases), Santa Cruz (5 cases), Tarija (3 cases) and Cochabamba (3 cases).

In Panama, on 15 October 2023, media reported 2 cases of hantavirus, bringing the cumulative number of cases nationally to 43 so far in 2023. There have been 2 hantavirus associated deaths in 2023; one in Herrera and one in Los Santos.

For all cases listed above, the type of hantavirus was not specified.

Lassa fever

In Nigeria, the Nigeria Centre for Disease Control and Prevention reported that 7,724 suspected and 1,095 confirmed Lassa fever cases have been registered from 113 Local Government Areas across 28 states. 188 deaths among the confirmed cases have been reported, resulting in a CFR of 17.2%.

In Liberia, from 6 January 2022 to 30 October 2023, 353 Lassa fever cases, including 27 deaths (CFR of 7.6%), were reported.

Lymphatic filariasis

On 16 October 2023, the WHO announced that the Lao People’s Democratic Republic has successfully eliminated lymphatic filariasis as a public health problem. This is the second neglected tropical disease that the country has eliminated following the elimination of trachoma as a public health problem in 2017.

Mpox

Within the African Region, as of 20 October 2023, 10,888 mpox cases (803 confirmed, 10,085 suspected) and 556 deaths have been reported in 7 endemic countries so far in 2023. The countries reporting the highest number of confirmed cases so far in 2023 include the DRC (n=597), Nigeria (n=79) and Central African Republic (n=67).

As of 31 October 2023, a total of 88 cases of mpox were reported in the UK so far in 2023. Of these, 83 were in England, 2 were in Scotland, one was in Wales and 2 were in Northern Ireland.

In Vietnam, on 24 October 2023, media reported the first fatal mpox case in the country, in a 29-year-old immunocompromised male.

Plague

In Madagascar, since the start of 2023 and as of 5 October 2023, 24 plague cases have been reported. Of the cases reported, 13 have been confirmed. Plague is endemic in Madagascar and every year cases presenting in bubonic and pneumonic forms are reported. The favourable season for transmission of the disease typically lasts from September to April.

Rubella

On 31 October 2023, the WHO announced elimination of rubella in the Democratic People’s Republic of Korea. The country introduced measles-rubella vaccine in the childhood immunisation programme in November 2019. Through mass immunisation campaigns, which achieved more than 99.8% coverage in the almost 6 million targeted population, the country rapidly built substantial population immunity for rubella.

Tick-borne encephalitis (TBE)

In Russia, media reported that as of 20 October 2023, 29 cases of TBE were reported in Buryatia, Rospotrebnadzor, during 2023. All the cases were un-vaccinated. Subsequent vaccination campaigns resulted in over 117,000 people, including 59,000 children, receiving a TBE vaccination within areas known to have TBE circulation.

Visceral leishmaniasis

On 31 October 2023, the WHO announced that Bangladesh had become the first country to eliminate visceral leishmaniasis as a public health problem. The country achieved the elimination target of less than one case per 10,000 population at the sub-district level in 2017 and has sustained it to date despite disruptions caused by the COVID-19 pandemic.

West Nile virus (WNV) 

Between July 2023 and 25 October 2023, European Union (EU) and European Economic Area countries have reported 673 human cases of WNV infection, of which the top 3 most affected countries were:

• Italy (313 cases; 20 deaths)

• Greece (161 cases; 21 deaths)

• Romania (100 cases; 12 deaths)

During the current 2023 WNV transmission season, autochthonous human cases of WNV infection were reported for the first time ever from:

• Ústecký kraj in Czechia

• Gironde, Charente-Maritime, Alpes-Maritimes, Charente and Haute-Corse in France

• Sömmerda in Germany

• Kastoria and Ioannina in Greece

• Imperia, Taranto, Lecce, Cosenza, Bari, Salerno and Verbano-Cusio-Ossola in Italy

• Gorj and Timiş in Romania

• Cáceres, Huelva, Valencia/València, Barcelona and Toledo in Spain.

EU-neighbouring countries have reported 91 human cases of WNV infection in Serbia (90) and North Macedonia (1) and 2 deaths in Serbia (2).

On 5 October 2023, the state Government of Massachusetts announced the fourth case of WNV in a resident to date in 2023, and updated the level of risk from low to moderate for counties across the state. As of 31 October 2023, 2,073 WNV cases have been reported from 46 states in the United States of America. Colorado, California and Nebraska have reported the most cases.

Novel pathogens and diseases

Rodent-borne viruses

Diversity and independent evolutionary profiling of rodent-borne viruses in Hainan, a tropical island of China

This study aimed to characterize the virome, analyze the phylogenetic evolution, and determine the diversity of rodent-borne viruses in Hainan Province, China. Multiple novel viruses carried by rodents in the Hainan Province were identified, including pestivirus and bocavirus in Leopoldoms edwardsi and bocavirus in Rattus andamanensis. The pathogenicity and associated impact of these novel viruses on humans and animals need to be evaluated in further studies.

Publications of interest

Cholera

Genomic epidemiology reveals multidrug resistant plasmid spread between Vibrio cholerae lineages in Yemen

Since 2016, Yemen has been experiencing its largest cholera outbreak in history. Multidrug resistance (MDR) emerged among Vibrio cholerae isolates from cholera patients in 2018. This study showed that treatment of severe cholera with macrolides between 2016 and 2019 coincided with the emergence of MDR cholera strains; which could have major implications for cholera control and thus highlighting the importance of genomic epidemiological surveillance to limit MDR spread.

EVEscape

Learning from prepandemic data to forecast viral escape

Contemporary approaches for predicting viral evolution are not available early in a pandemic. This study demonstrated that EVEscape, a flexible framework that combines fitness predictions with biophysical and structural information, was able to forecast pandemic escape mutations and further predict emerging strains with high escape potential.

Marburg virus

Micro‒Global Positioning Systems for Identifying Nightly Opportunities for Marburg Virus Spillover to Humans by Egyptian Rousette Bats

In Uganda, a study found that Egyptian rousette bats frequently travelled up to 57km to feed in peripheral agricultural areas, where they had easy access to human cultivated fruits and wild fruiting trees that were used by humans and domestic livestock. The study demonstrated that bat foraging behavior represents a Marburg virus spillover risk to humans and plausibly explains the origins of some past outbreaks.

Nipah Virus

Nipah Virus: An Overview of the Current Status of Diagnostics and Their Role in Preparedness in Endemic Countries

The limited number of serological tests for Nipah virus and the current lack of standardization prevents the recommendation and diagnostic use of them. This review recommends the development, assessment, and standardization of point-of-care assays for the rapid diagnosis of Nipah Virus.

Sudan ebolavirus

Molecular characterization of the 2022 Sudan virus disease outbreak in Uganda

In September 2022, Uganda declared its fifth Sudan ebolavirus outbreak in Mubende District, which resulted in 142 confirmed and 22 probable cases by January 2023. Genetic relatedness analysis of the newly emerged Mubende variant indicated that it was most closely related to the Nakisamata Sudan ebolavirus sequence from 2011, represented a likely new zoonotic spillover event, and exhibited an inter- and intra-outbreak substitution rate consistent with previous outbreaks. The most recent common ancestor for the Mubende variant was estimated to have occurred in October and November 2021. The study findings support the need to integrate the genetic sequencing and epidemiological data in response activities and identifying new zoonotic spillover events.

Tick-borne diseases

Tick-Borne Diseases of Humans and Animals in West Africa

This review described tick-borne pathogens reported in people, animals and ticks in West Africa by microscopic, immunological and molecular methods. The aim of this review was to describe human and animal tick-borne diseases in West Africa using a one-health approach.

Zoonoses

Backyard zoonoses: The roles of companion animals and peri-domestic wildlife

This review presents background and commentary focusing on companion and peri-domestic animals as disease risk for humans, considering the human-animal interface and population dynamics between the animals themselves.

Related resources

1. High consequence infectious diseases monthly summaries

2. National flu and COVID-19 surveillance reports

3. Avian influenza (influenza A H5N1): technical briefings

4. Avian influenza (bird flu) in Europe, Russia and the UK reports

5. Bird flu (avian influenza): latest situation in England updates

6. Human Animal Infections and Risk Surveillance (HAIRS) group risk assessments and statements

7. Animal and Plant Health Agency (APHA) monitoring of disease in livestock and poultry monthly reports

Authors of this report

UKHSA’s Emerging Infections and Zoonoses team epiintel@ukhsa.gov.uk