Infectious disease surveillance and monitoring for animal and human health: summary January to June 2023
Updated 25 April 2024
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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 webpage.
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 focusses 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 |
|---|---|---|
| Dengue | Region of the Americas | Update |
| Lassa fever | African region | Update |
| Marburg virus disease | Equatorial Guinea and Tanzania | New |
Dengue – Region of the Americas
Event summary
Since the beginning of 2023, the Region of the Americas has reported the greatest number of dengue cases compared to other World Health Organization (WHO) regions. Between January 2023 and 1 July 2023, 2,997,097 dengue cases, including 1,302 deaths (case fatality rate of 0.04%), were reported in the Region of the Americas. This surpassed the number of cases reported during the equivalent 2022 period (2.8 million cases).
Between January and June 2023, the countries reporting the highest number of dengue cases include Brazil (2,376,522 cases; 769 deaths), Peru (188,326 cases; 325 deaths) and Bolivia (133,779 cases; 77 deaths).
Dengue case numbers in the Region of the Americas peaked earlier in 2023 (approximately epidemiological week 15) compared to 2022 (epidemiological week 18) (Figure 1). Cases in the region continue to decline.
Figure 1. Dengue: cumulative and average case numbers, Region of the Americas, 2022 to 2023
Figure 1 data as of 1 July 2023. WHO. Accessed: 19 July 2023.
Incident assessment
Dengue epidemics in the Region of the Americas occur cyclically every 3 to 5 years. During 2023, significant outbreaks have been recorded in the region which have surpassed levels of previous years – partially attributed to, and exacerbated by, warm and rainy weather from cyclone Yaku and the El Niño effect in April and May. Both phenomena have likely supported the breeding of Aedes aegypti mosquitoes, and climate change may have also supported the geographical expansion of dengue outside of historical areas of transmission. Further, improvements in surveillance following the COVID-19 pandemic may have resulted in an overall increase in case reporting.
While severe disease in a case is possible, transmission risk within the wider UK population is negligible given the lack of established vector populations necessary for transmission. Given the small number of travel-associated infections imported into the UK annually, established processes for the diagnosis of cases, previous experience in treatment and the use of appropriate therapeutics, the risk to the UK remains very low.
Lassa fever – African region
Figure 2. Geographical distribution of Lassa fever cases (confirmed and suspected) and deaths, between January and June 2023
Darker shades of blue represent a higher number of total cases (confirmed and suspected) while lighter shades represent a lower number of cases, as based on Table 1 below.
Table 1. Number of Lassa fever cases by country, between January and June 2023
| Country | Confirmed cases | Suspected cases | Deaths (among confirmed cases) |
|---|---|---|---|
| Nigeria | 974 | 6,161 | 169 |
| Liberia | 80 | 0 | 23 |
| Ghana | 27 | 0 | 1 |
| Sierra Leone | 2 | 0 | 2 |
| Guinea | 1 | 0 | 1 |
| Total | 1,081 | 6,161 | 196 |
These are approximate numbers based on available information.
Event summary
Between 1 January and 25 June 2023, Nigeria’s Centre for Disease Control and Prevention reported 974 confirmed and 6,161 suspected cases of Lassa fever. 169 deaths were reported amongst confirmed cases (case fatality rate of 17.4%). This is an increase in confirmed cases compared to the equivalent 2022 period (820 confirmed cases including 164 deaths; case fatality rate of 20.0%). Cumulatively during 2022, 1,067 confirmed and 8,202 suspected cases of Lassa fever were reported in Nigeria. The increase in case numbers during 2023 may be partly attributable to improved surveillance and laboratory diagnostics across the country.
In Ghana, an outbreak of Lassa fever was declared in the Greater Accra Region on 24 February 2023. The last case was confirmed on 1 March 2023. A total of 27 confirmed cases of Lassa fever, including one death (case fatality rate of 1%) were reported. Ghana declared the Lassa fever outbreak over on 2 May 2023.
From 1 January to 25 June 2023, a total of 80 confirmed cases of Lassa fever including 23 deaths (case fatality rate of 29%) have been reported in Liberia.
On 13 February 2023, media reported 2 epidemiologically-linked fatal cases of Lassa fever in Bo District, Southern Province, Sierra Leone.
On 21 March 2023, one confirmed fatal case of Lassa fever in a child aged 3 years was reported from Nzérékoré health district in Guinea.
Incident assessment
Lassa fever is endemic in the countries listed above, and so human cases are not unexpected. The UK has previous experience in the management of a small number of Lassa fever cases. In 2022, 3 travel-related cases of Lassa fever were reported in the UK. Prior to this, 13 imported cases of Lassa fever had been reported since 1971, all in travellers from West African countries, including Nigeria, Sierra Leone and Mali. Whilst severe disease in a case is possible, transmission within the wider UK population is highly unlikely as there are well established processes for the isolation and rapid diagnostics of Lassa fever cases, as well as a range of robust clinical, infection prevention and control measures available within healthcare settings.
Marburg virus disease (MVD) – Equatorial Guinea and Tanzania
Event summary
On 13 February 2023, the Ministry of Health and Social Welfare of Equatorial Guinea declared an outbreak of MVD, after a case of MVD was confirmed in Kié Ntem Province, in the north-east of the country. This was the first ever outbreak of MVD to be reported in Equatorial Guinea. Between 13 February and 7 June 2023, 17 confirmed (12 deaths) and 23 probable (all fatal) cases (Figure 3) were reported from 6 districts across 4 provinces (Centro Sur, Kié Ntem, Litoral and Wele-Nzas).
The last confirmed case of MVD was reported from Bata District in Litoral Province, on 7 April 2023. The MVD outbreak in Equatorial Guinea was declared over on 8 June 2023, after 42 days without a new confirmed case being reported.
Figure 3. Confirmed and probable Marburg virus disease cases by week of symptom onset, Equatorial Guinea
Figure 3 data as of 1 May 2023. WHO. Accessed: 6 September 2023.
On 21 March 2023, health authorities in Tanzania declared the country’s first ever outbreak of MVD. Tanzania’s National Public Health Laboratory analysed samples to determine the cause of illness after 8 people developed symptoms including fever, vomiting, bleeding and renal failure. A total of 161 contacts were identified and monitored. Between 21 March and 31 May 2023, one probable and 8 laboratory confirmed MVD cases (including 6 deaths and 3 recoveries) were reported (Figure 4). All cases were reported from Bukoba District, Kagera region. The MVD outbreak in Tanzania was declared over on 2 June 2023.
There is no evidence suggesting that the outbreaks in Equatorial Guinea and Tanzania were linked.
Figure 4. Confirmed and probable Marburg virus disease cases by week of symptom onset, Tanzania
Figure 4 data as of 30 April 2023. WHO. Accessed: 6 September 2023.
Incident assessment
Both outbreaks were assessed by the EIZ team as being a very low risk to the UK public. The risk of MVD exposure to UK Nationals in the affected countries was assessed as very low. Transmission requires direct contact with blood, secretions, organs or other bodily fluids of deceased or living infected people or animals, which would be considered unlikely exposures for tourists and other travellers. Risks can be mitigated further by following precautionary measures to prevent infection. The probability of an MVD case associated with these outbreaks being imported into the UK was assessed as very low, due to the small number of travellers expected between the UK and MVD affected areas in Equatorial Guinea and Tanzania. The impact of an imported MVD case on the UK population was assessed as very low. To date, there have been no reported cases of MVD in the UK. There are a range of robust clinical, infection prevention and control measures available for viral haemorrhagic fevers which could have been adapted for use as necessary.
Other incidents of interest
Summary of other incidents
| Disease or infection | Location |
|---|---|
| Avian influenza | Cambodia Chile China Ecuador UK |
| Plague (bubonic) | Democratic Republic of Congo Madagascar Mongolia USA |
| Cholera | Multi-country |
| COVID-19 | Multi-country |
| Hantavirus | Argentina Bolivia Chile |
| Measles | Multi-country |
| Mpox | Multi-country |
| Nipah virus infection | Bangladesh |
| Polio | Multi-country |
| Yellow fever | Multi-country |
| Zika virus | Multi-country |
Avian influenza
Table 2. Number of human cases by country and avian influenza subtype, between January and June 2023
| A(H5N1) | A(H3N8) | A(H5N6) | A(H9N2) | |
|---|---|---|---|---|
| Cambodia | 2 | 0 | 0 | 0 |
| Chile | 1 | 0 | 0 | 0 |
| China | 1 | 1 | 3 | 8 |
| Ecuador | 1 | 0 | 0 | 0 |
| UK | 2 | 0 | 0 | 0 |
| Total | 7 | 1 | 3 | 8 |
Situation summary
Avian influenza A(H5N1)
Between January and June 2023, human cases of avian influenza A(H5N1) were reported from Cambodia, Chile, China, Ecuador and the UK. In January 2023, Ecuador reported one human case of avian influenza A(H5N1) in a girl aged 9 years following exposure to live poultry. This was the first reported case of human infection caused by avian influenza A(H5N1) in the Latin America and the Caribbean region.
In late February 2023, 2 human cases of avian influenza A(H5N1), including one death, were reported from Prey Veng Province, Cambodia. These were the first confirmed cases to be reported in Cambodia since 2014. The cases, who were family contacts, likely acquired the infection from infected poultry. There is no evidence of human-to-human transmission.
China reported a human case of avian influenza A(H5N1), first detected in early February 2023 in the Jiangsu Province, following exposure to live domestic poultry.
In March 2023, Chile reported its first known human case of avian influenza A(H5N1). Although the source of infection is unclear, between December 2022 and February 2023, avian influenza A(H5N1) was detected in wild birds (pelicans and penguins) and sea lions in the Antofagasta Region where the case resides.
In May 2023, 2 cases of avian influenza A(H5N1) in England were detected in poultry workers. Both cases were asymptomatic and were detected as part of an ongoing enhanced surveillance study of asymptomatic workers exposed to poultry infected with avian influenza.
Avian influenza A(H3N8)
In March 2023, China reported a fatal human case of avian influenza A(H3N8) with a history of exposure to live poultry. Environmental samples were collected from the patient’s residence and a wet market the patient had frequented before the onset of illness. Samples collected from the wet market were positive for avian influenza A(H3). This is the third reported human infection with avian influenza A(H3N8) from China; 2 previous cases were reported in April and May 2022.
Avian influenza A(H5N6)
China reported 3 human cases of avian influenza A(H5N6) between 1 January and 30 June 2023. The first case was reported in January 2023 in a male aged 54 years from Hunan Province, China. The case had symptom onset on 2 November 2022 and was hospitalised on 5 November 2023 in a critical condition. On 1 March 2023, a case of avian influenza A(H5N6) involving a male aged 49 years was reported from Guangdong Province. The case had exposure to domestic poultry prior to symptom onset on 17 December 2022. The case was hospitalised on 21 December 2022 in a critical condition. A third case was reported on 5 June 2023, in a female aged 54 years from Sichuan Province, also following exposure to domestic poultry. The case had symptom onset on 19 May 2023 and was hospitalised the same day in a critical condition. For all 3 cases, the outcome is not known.
Avian influenza A(H9N2)
Between 1 January and 29 June 2023, 8 human cases of avian influenza A(H9N2) were reported by the WHO, all from China (including 4 cases with a symptom onset date in 2022) (Table 3). As of 29 June 2023, a total of 89 cases of human infection with avian influenza A(H9N2), including 2 deaths (both with underlying conditions), have been reported to WHO in the Western Pacific Region since December 2015. Of these, 87 were reported from China and 2 were reported from Cambodia. The last case was reported from China, with an onset date of 30 May 2023 and has since recovered.
Table 3. Summary of human cases of avian influenza A(H9N2) reported by the WHO between January and June 2023, from China
| Reporting date | Symptom onset date | Sex | Age | Province | Exposure (most likely) |
|---|---|---|---|---|---|
| 6 January 2023 | 19 October 2022 | Male | 58 years old | Hunan | Live poultry market |
| 6 January 2023 | 23 October 2022 | Female | 5 years old | Gansu | Unknown |
| 6 January 2023 | 13 November 2022 | Male | 3 years old | Anhui | Live poultry market |
| 24 March 2023 | 19 October 2022 | Female | 10 years old | Hunan | Unknown |
| 24 March 2023 | 31 January 2023 | Female | 3 years old | Jiangxi | Backyard poultry in Hunan Province |
| 24 March 2023 | 5 February 2023 | Male | 2 years old | Hunan | Backyard poultry |
| 1 June 2023 | 1 May 2023 | Male | 7 months old | Jiangxi | Backyard poultry |
| 23 June 2023 | 30 May 2023 | Female | 6 years old | Sichuan | Live poultry market |
Bubonic plague
In the Democratic Republic of the Congo (DRC), the 9th outbreak of bubonic plague was announced by the Provincial Health Division of Ituri Province on 4 April 2022, affecting the Rethy health zone, Djugu territory. Plague is endemic in this part of the country. From the beginning of January 2023 to 14 June 2023, 29 bubonic plague cases, including 4 deaths, have been recorded.
On 23 March 2023, media reported 4 cases and 3 deaths from bubonic plague in Ambositra, Madagascar, where the disease is endemic.
On 27 June 2023, the Colorado Department of Public Health reported one case of plague in an adult in Montezuma County, Colorado.
On 29 June 2023, media reported one case of bubonic plague in a shepherd from the Govi-Altai Province of Mongolia.
Cholera
Between 1 January and 15 June 2023, 24 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. As such, the WHO continues to assess the risk of cholera at the global level as very high.
The WHO African Region remains the most affected region, with 14 countries reporting cholera cases since the beginning of 2023. Since mid-May 2023, and as of 29 June 2023, an increase in the number of cases has been reported in South Africa with ongoing geographic spread to new areas. As of 29 June 2023, 1,301 cholera cases and 43 deaths had been reported since the outbreak began in February 2023.
While the number of weekly reported cholera cases remains high, according to the latest available data, outbreaks appear to have stabilised in recent weeks in Cameroon, the DRC, Mozambique and Zimbabwe. Additionally, improvements in the epidemiological situation have been reported in Malawi in recent weeks. The outbreak began in February 2022 and was declared a national public health emergency in December 2022. As of the end of June 2023, 58,919 cholera cases and 1,185 deaths were reported. The increase in cholera cases during 2023 can be partly attributed to the impact of Cyclone Freddy, which hit the Southern region of Malawi on 12 March 2023, affecting 14 districts and 2 cities.
Since 1 January 2023, and as of 4 June 2023, 9,391 cholera cases, including 28 deaths have been reported in Somalia. No cases were reported during the equivalent 2022 period. The outbreak has been associated with a higher proportion of people with limited access to safe water, alongside uncontrolled cross border movement in Somalia, Kenya and Ethiopia triggered by drought.
Other notable outbreaks have been reported from the WHO Eastern Mediterranean region (EMRO). 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. Between 1 January and 30 June 2023, 6 EMRO member states reported cholera cases, including: Afghanistan (79,984 cases; 34 deaths), Syria (69,886 cases; 104 deaths), Somalia (10,446 cases; 29 deaths), Yemen (3,878 cases; 4 deaths), Pakistan (51 cases; 0 deaths) and Lebanon (2,197 cases; 0 deaths). On 11 June 2023, the Lebanese Ministry of Health declared the cholera outbreak over. This was the first outbreak reported in the country since 1993.
As of 30 June 2023, 51,998 cholera cases, including 525 deaths, were reported from Haiti, since the first confirmed case was registered on 3 October 2022. A decreasing trend in reported cholera cases has been observed during June 2023.
COVID-19
By the end of June 2023, over 767 million confirmed COVID-19 cases and 6.9 million deaths had been reported globally. Over 13.4 billion vaccine doses had been administered globally, as of 28 June 2023. According to the WHO, reported cases are not an accurate representation of infection rates due to the reductions in testing and reporting globally.
Over one million new cases and over 5,700 deaths were reported between 29 May and 25 June 2023. While 5 WHO regions reported decreases in both cases and deaths, the African Region reported a decrease in cases but an increase in deaths. During this 28-day period, 62% (146 of 234) of countries and territories reported at least one case – a proportion that has been declining since mid-2022.
Hantavirus
Between January and June 2023, 2 fatal hantavirus cases were reported in Argentina; one in March from Santa Fe and one from Buenos Aires in April. Hantavirus cases have also been recorded in Bolivia, with one case each reported from Tarija (in January) and Villa Tunari, Cochabamba (in April), whilst a fatal case was reported on 9 June 2023 from Abel Iturralde Province, north La Paz. In Chile, 32 hantavirus cases, including 6 deaths, were reported this year, as of 28 May. A higher number of cases were reported in Chile during the first 6 months of 2023, than in the whole of 2022 (25 cases and 6 deaths). In all cases outlined above, the type of hantavirus was not specified.
Measles
Large outbreaks of measles continue to be reported globally, mostly across the African, Middle East and Asian regions. From January to June 2023, countries reporting the highest number of measles cases include Yemen (9,418 cases as of 17 April 2023), Ethiopia (6,933 cases as of 1 May 2023), Cameroon (4,152 cases as of 7 May 2023), Pakistan (2,616 cases as of 20 June 2023), Indonesia (2,161 cases as of 3 April 2023) and Turkey (1,440 cases as of 21 June 2023). Other countries reporting outbreaks included the DRC, Nigeria, Colombia, the Philippines and South Africa, although the recent outbreak of measles in South Africa is now considered over in most provinces.
Mpox
From the beginning of January to June 2023, mpox transmission continued at a low pace and has remained stable over the last couple of months. As of 26 June 2023, 88,060 laboratory-confirmed and 1,097 probable cases of mpox, including 147 deaths, have been reported to WHO from 112 Member States across all 6 WHO regions. During June 2023, most reported cases were from the Western Pacific Region and the Region of the Americas. 6 countries reported an increase in the number of cases, with the highest increase reported in China. The frequency of reporting has decreased substantially, leading to delays between case detection and reporting at the global level.
Detection of cases of mpox acquired within the UK were first confirmed in England from May 2022. The outbreak has mainly been in gay, bisexual, and other men who have sex with men without documented history of travel to endemic countries. As of 31 May 2023, a total of 3,753 cases of mpox were reported in the UK – an increase of 21 cases since 31 December 2022.
Nipah virus
From the beginning of January to 4 March 2023 (latest available data), 14 Nipah virus cases, including 10 deaths (case fatality rate 71.4%), were reported in Bangladesh – the highest case numbers reported since 2015. Nipah virus was first identified in Bangladesh in 2001. Since then, the country has reported seasonal outbreaks between December and May, coinciding with the date palm harvesting season and subsequent consumption of date palm sap; the fruits of which can become contaminated by infected bats. 335 Nipah virus cases, including 237 deaths, have been reported since 2001.
Polio
Wild polio virus type 1 (WPV1)
Between 1 January and 27 June 2023, a total of 6 cases of WPV1 were reported to the Global Polio Eradication Initiative including 5 cases from Afghanistan and one case from Pakistan. This is a reduction from 12 cases reported in the equivalent 2022 period. WPV1 is endemic in Afghanistan and Pakistan.
Circulating vaccine derived polio virus (cVDPV)
As of 28 June 2023, 127 cases of cVDPV (types 1, 2 and 3) have been reported globally since 1 January 2023. This is a decrease from 154 cases reported in the same period in 2022.
Collectively, 44 cases of cVDPV type 1 were reported from the DRC (28 cases), Madagascar (13 cases) and Mozambique (3 cases).
83 cases of cVDPV type 2 were reported from Benin (3 cases), Central African Republic (7 cases), Chad (8 cases), Côte d’Ivoire (2 cases), the DRC (43 cases), Mali (3 cases), Nigeria (10 cases), Somalia (2 cases), Indonesia (3 cases), Israel (one case) and Zambia (one case).
Yellow fever
As of 2023, 34 countries in Africa and 13 countries in Central and South America are either endemic for, or have regions that are endemic for, yellow fever.
Between 1 January and 10 June 2023, 56 suspected cases of yellow fever were reported in Liberia. Of 45 tested samples, 27 (64%) were negative.
From 1 January to 24 April 2023, 194 cases of yellow fever were reported nationwide in Uganda. 4 cases were confirmed in Buikwe (2 cases), Buvuma (one case) and Kasese (one case) districts.
As of 25 April 2023, 9 yellow fever cases have been confirmed in the Americas. 2 cases in Bolivia including one yellow fever case from Santa Cruz, where yellow fever had not been reported for 19 years. In Brazil, 3 yellow fever cases were confirmed in Sao Paulo.
On 8 May 2023, one confirmed case of yellow fever was reported in Côte d’Ivoire, with onset of illness on 4 April 2023.
On 7 June 2023, one confirmed case of yellow fever was reported from Ziguinchor region, southern Senegal with a date of disease onset of 29 May.
Zika virus
Between 1 January and 30 June 2023, 26,854 Zika virus disease cases, including 2,733 confirmed cases and 3 related deaths, were registered throughout the region of the Americas. Of the total confirmed cases, 2,723 were reported from Brazil, 7 from Bolivia, 2 in Mexico and one in Peru.
Travel associated infections have been reported by Hungary (2 Zika virus cases in February) and Taiwan (2 Zika virus cases in May), in individuals that had travelled to Thailand and the Maldives, respectively.
On 15 May 2023, the Amazonas Health Surveillance Foundation in Brazil issued an alert to professionals and residents of the state, having registered over 100 confirmed Zika virus disease cases, including 19 cases in pregnant women.
In Singapore, 15 Zika virus cases were reported from January to 31 May 2023, with 14 cases detected in the month of May alone. At least 3 Zika virus cases were locally acquired.
Novel pathogens and diseases
Oz virus (OZV): Japan
Oz virus (OZV) is a novel RNA virus classified into the genus Thogotovirus of the family Orthomyxoviridae. It was first isolated from ticks in Japan in 2018. On 23 June 2023, Japan’s National Institute of Infectious Diseases published a case report on the first human infection with OZV, which occurred in the summer of 2022. A recent seroprevalence study suggests OZV may be widely distributed in western and eastern Japan, and is most likely transmitted via an infected bite from Ambylomma testudinarium ticks, whose habitats coincide with OZV-infected animals. There have been no other known reports of serum antibody or virus detection in either animals or humans outside of Japan.
Haseki tick virus
In March 2023, researchers reported the novel Haseki tick virus (HSTV), detected in ixodid ticks and patients in the Asian region of Russia. Sequencing of genome fragments demonstrated that HSTV is closely related to unclassified Flavi-like viruses. HSTV (following an Ixodes persulcatus bite) was detected in hospitalised patients in the city of Vladivostok, including cases with mixed infections of HSTV, tick-borne encephalitis, Borrelia and Anaplasma species. HSTV appears to circulate in at least 2 regions of Russia. Further research is needed to describe the distribution of HSTV infections and tick species globally.
Coxiella burnetii
Coxiella burnetii is an obligate intracellular bacterial pathogen that has been identified in multiple marine mammal species. In June 2023, researchers reported that sequencing of Coxiella extracts from Australian fur seals revealed a new Australian marine mammal isolate of Coxiella (PG457). The presence of multiple virulence factors appears to give this genotype sufficient pathogenicity for it to be considered a possible causative agent of abortion in Australian fur seals, as well as a potential zoonotic risk.
Yezo virus
Yezo virus (YEZV), a novel tickborne orthonairovirus, was discovered in Japan in 2021. A further study identified YEZV infection in a febrile patient who had a tick bite in north-eastern China, where 0.5% of Ixodes persulcatus ticks tested were positive for viral RNA. Phylogenetic analysis confirmed the association between febrile illness and the virus. Clinical manifestations of the YEZV-infected patient in China were milder than those reported for patients in Japan.
Publications of interest
Andes virus
A recent phase 1, double-blind, clinical trial for a novel Andes virus DNA vaccine found the vaccine to be safe and that it induced a robust and durable immune response in healthy adult volunteers. Seropositivity was found to be sustained for a prolonged period.
This is the first hantavirus pulmonary syndrome vaccine that has advanced to human clinical trials. This study provides evidence to support advancement to larger-scale testing of this vaccine candidate.
Borrelia
In southern England, a study found that the density of nymphs (ticks), Borrelia prevalence, and the density of Borrelia infected nymphs did not differ significantly along an urban–rural gradient.
This suggests the risk of Lyme borreliosis transmission could be similar or increased in urban woodlands if there is higher public footfall. Additional research is needed to further investigate this risk.
Chikungunya
There is currently no approved vaccine for chikungunya virus infections.
A recent double-blind, phase 3 clinical trial of a single-shot live-attenuated chikungunya vaccine (VLA1553) found the vaccine candidate was able to induce seroprotective chikungunya virus neutralising antibodies in 98.9% of participants, 28 days post-vaccination, independent of age.
VLA1553 was also found to be generally safe and tolerable, indicating that the vaccine is a good candidate for the prevention of chikungunya virus disease.
In June 2023, Bavarian Nordic announced initial results of their double-blind phase 3 clinical trial of the virus-like particle (VLP)-based chikungunya virus vaccine candidate CHIKV VLP (PXVX0317).
The vaccine candidate was immunogenic in 87% of the participants (healthy adults aged 65 years and older). CHIKV VLP was well-tolerated in this adult population.
The trial will continue for a 6-month follow-up for both safety and immunogenicity.
Cholera
Development of a simple, rapid, and sensitive molecular diagnostic assay for cholera
A recent study outlines the development of a rapid, sensitive diagnostic assay, Rapid LAMP based Diagnostic Test (RLDT), to detect cholera in areas with limited laboratory infrastructure.
Using this rapid test, which is cold-chain and electricity free, cholera could be detected directly from stool and environmental water samples in under an hour. Field evaluations of cholera RLDT are currently underway in parts of South Asia and Africa.
Chondrostereum purpureum
Paratracheal abscess by plant fungus Chondrostereum purpureum- first case report of human infection
A recent case study outlined the first reported instance of the plant fungus Chondrostereum purpureum causing disease in a human.
The pathogen could only be identified via genomic sequencing analysis, and not by conventional microscopy and culture techniques, highlighting the importance of molecular techniques in identifying causative fungal species in human infection.
COVID-19
Paratracheal abscess by plant fungus Chondrostereum purpureum- first case report of human infection
A multicentre, open-label phase 3 trial for aerosolised Ad5-nCoV, a licensed mucosal respiratory vaccine against SARS-CoV-2, found the vaccine candidate to be safe and immunogenic in boosting systemic and mucosal immunity against omicron SARS-CoV-2 subvariants.
The authors state that the results support the use of aerosolised Ad5-nCoV to enhance the level of vaccine protection in adults.
Ebola virus disease
A Pan-ebolavirus Monoclonal Antibody Cocktail Provides Protection against Ebola and Sudan Viruses
A recent study found that 2 distinct cross-reactive monoclonal antibodies (mAbs), which were isolated from mice immunised with a recombinant filovirus vaccine, were able to provide protection against Ebola virus disease (EVD) in animal models.
In combination, the mAbs provided 100% protection against Sudan ebolavirus challenge in guinea pigs.
Currently there are no licensed therapeutics for the prevention and treatment of EVD caused by Sudan ebolavirus.
IAVI starts first-in-human Phase I clinical trial of single-dose Sudan ebolavirus vaccine candidate
IAVI have also announced the initiation of their first-in-human Phase I clinical trial for a Sudan ebolavirus vaccine candidate (IAVI C108) which uses the recombinant vesicular stomatitis virus viral vector.
The trial will evaluate the safety and immunogenicity of IAVI C108 in healthy adults.
Henipavirus (Langya virus)
Structure and antigenicity of divergent Henipavirus fusion glycoproteins
In August 2022, the novel Langya virus (LayV), closely related to Mòjiāng virus (MojV), and divergent from the bat-borne henipavirus (HNV) members; Nipah (NiV) and Hendra (HeV) viruses, was isolated in China.
The spillover of LayV is the first reported instance of a HNV zoonosis to humans outside of NiV and HeV.
A study showed the LayV and MojV F proteins adopt an overall similar structure to NiV but are antigenically distinct as they do not react to known antibodies or sera.
Lassa fever
There is currently no licenced vaccine that protects against Lassa fever.
A randomised, place-controlled, first-in-human phase 1 trial of a recombinant measles-vectored Lassa fever vaccine candidate (MV-LASV) found it showed acceptable safety, tolerability, and immunogenicity in participating adults. Immunogenicity did not appear to be affected by pre-existing immunity against the measles vector.
Lassa fever vaccine candidates: A scoping review of vaccine clinical trials
A recent scoping review highlighted 3 additional Lassa fever vaccine candidates (INO-4500, rVSV∆G-LASV-GPC, and EBS-LASV) currently undergoing clinical assessment and evaluation in humans.
A total of 4 phase 1 trials in healthy adults and one phase 2 trial involving participants aged from 18 months to 70 years old are being conducted thus far.
Although Lassa fever vaccine development is still in the early stages, current progress towards a safe and effective vaccine is promising.
Marburg virus
There are currently no approved vaccines against Marburg virus.
The first-in-human, phase 1, open-label, dose-escalation trial for chimpanzee adenovirus type 3-vectored Marburg virus (cAd3-Marburg) vaccine in adults was found to be safe, tolerable, and immunogenic. 95% of participants produced a glycoprotein-specific antibody response at 4 weeks after a single vaccination, which remained in 70% of participants at 48 weeks.
Future planned trials include an outbreak response clinical protocol in Ghana, a phase 1b clinical trial in the USA and a phase 2 clinical trial in Kenya and Uganda.
Polio
A randomised controlled trial looking at co-administering the novel oral poliovirus vaccine type 2 (nOPV2) vaccine against poliovirus type 2 alongside the bivalent oral poliovirus vaccine against poliovirus type 1 and 3 found immunogenic interference for poliovirus type 2, but not for types 1 and 3.
This highlights a major limitation of this as a potential polio vaccination strategy.
Genetic stabilization of attenuated oral vaccines against poliovirus types 1 and 3
As an RNA virus, OPV rapidly evolves, which can result in vaccine-derived, virulent poliovirus variants. Circulation of these variants in under immunized populations can lead to further evolution of circulating, vaccine-derived poliovirus, and therefore posing a risk of polio re-emergence.
In a recent study, new vaccine candidates against type 1 (nOPV1) and 3 (nOPV3) polioviruses were developed by replacing the capsid coding region of the nOPV2 vaccine with that from Sabin 1 or 3. The new candidates remain attenuated, conserve nOPV2 genetic stability characteristics, and remain highly immunogenic in mice.
Powassan virus
Powassan Virus Lineage I in Field-Collected Dermacentor variabilis Ticks, New York, USA
A recent study in southern New York, USA, confirmed Powassan virus (POWV) lineage I, in Dermacentor variabilis (D. variabilis) ticks, suggesting either spill over from the typical Ixodes cookei tick sylvatic cycle, a unique D. variabilis species-dependent sylvatic cycle for POWV lineage I, or a unique subtype of the virus specific to D. variabilis ticks with an unknown sylvatic cycle.
Tacheng tick virus-1 and Jingmen tick virus
Jingmen tick virus (JMTV) and TcTV-1 have recently been confirmed to cause disease in humans in China.
JMTV and TcTV-1 were detected in tick specimens collected in Turkey between 2020 and 2022, and genomic analysis revealed that the virus strains are closely related to those found in China, indicating the geographical expansion of the viruses as well as their ability to extend to other tick species.
Tick-borne encephalitis
Spatiotemporal spread of tick-borne encephalitis in the EU/EEA, 2012 to 2020
A recent study investigated the spatiotemporal changes of tick-borne encephalitis (TBE) in the EU/EEA between 2012 to 2020, with 19 countries reporting a cumulative total of 29,974 cases, of which 98.6% were locally acquired infections.
TBE cases increased during this period, with a north-west spread observed in continental Europe. Czechia, Germany, and Lithuania accounted for 52.9% of all cases, with the increasing number of observed cases per year outpacing the predicted number of cases.
The influenza-like or asymptomatic nature of many TBE virus infections, means that infections can remain undetected.
A seroprevalence study in south-western Germany found the incidence of predominantly silent TBE virus infections (>250 per 100,000/year) greatly exceeded the incidence of notified cases (4.7 per 100,000/year), concluding that the risk of TBEV infection is much higher than previously thought.
Zika virus
There are currently no approved vaccines against Zika virus.
The results of 2 randomised phase 1 clinical trials for mRNA-based Zika virus vaccine candidates (mRNA-1325 and mRNA-1893) in adults found that mRNA-1893 was well tolerated at all dose levels evaluated and it also induced Zika virus-specific neutralising antibody responses, after 2 doses, independent of flavivirus serostatus.
The study findings support the continued development of mRNA-1893 against Zika virus.
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