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Avian influenza subtype A(HxNy) viruses are zoonotic and may occasionally infect humans through direct or indirect contact, resulting in mild to severe illness and death. Member States in the Western Pacific Region (WPR) communicate and notify the World Health Organization of any human cases of A(HxNy) through the International Health Regulations (IHR 2005) mechanism. This report includes all notifications in the WPR with illness onset dates from 1 November 2003 to 31 July 2022. During this period, there were 1972 human infections with nine different A(HxNy) subtypes notified in the WPR. Since the last report, an additional 134 human avian influenza infections were notified from 1 October 2017 to 31 July 2022. In recent years there has been a change in the primary subtypes and frequency of reports of human A(HxNy) in the region, with a reduction of A(H7N9) and A(H5N1), and conversely an increase of A(H5N6) and A(H9N2). Furthermore, three new subtypes A(H7N4), A(H10N3) and A(H3N8) notified from the People’s Republic of China were the first ever recorded globally. The public health risk from known A(HxNy) viruses remains low as there is no evidence of person-to-person transmission. However, the observed changes in A(HxNy) trends reinforce the need for effective and rapid identification to mitigate the threat of a pandemic from avian influenza if person-to-person transmission were to occur.

The first case of coronavirus disease 2019 (COVID-19) in Cambodia was confirmed on 27 January 2020 in a traveller from Wuhan. Cambodia subsequently implemented strict travel restrictions, and although intermittent cases were reported during the first year of the COVID-19 pandemic, no apparent widespread community transmission was detected. Investigating the routes of severe acute respiratory coronavirus 2 (SARS-CoV-2) introduction into the country was critical for evaluating the implementation of public health interventions and assessing the effectiveness of social control measures. Genomic sequencing technologies have enabled rapid detection and monitoring of emerging variants of SARS-CoV-2. Here, we detected 478 confirmed COVID-19 cases in Cambodia between 27 January 2020 and 14 February 2021, 81.3 per cent in imported cases. Among them, fifty-four SARS-CoV-2 genomes were sequenced and analysed along with representative global lineages. Despite the low number of confirmed cases, we found a high diversity of Cambodian viruses that belonged to at least seventeen distinct PANGO lineages. Phylogenetic inference of SARS-CoV-2 revealed that the genetic diversity of Cambodian viruses resulted from multiple independent introductions from diverse regions, predominantly, Eastern Asia, Europe, and Southeast Asia. Most cases were quickly isolated, limiting community spread, although there was an A.23.1 variant cluster in Phnom Penh in November 2020 that resulted in a small-scale local transmission. The overall low incidence of COVID-19 infections suggests that Cambodia’s early containment strategies, including travel restrictions, aggressive testing and strict quarantine measures, were effective in preventing large community outbreaks of COVID-19.

In February 2021, routine sentinel surveillance for influenza-like illness in Cambodia detected a human avian influenza A(H9N2) virus infection. Investigations identified no recent H9N2 virus infections in 43 close contacts. One chicken sample from the infected child's house was positive for H9N2 virus and genetically similar to the human virus.

Introduction of non-pharmaceutical interventions to control COVID-19 in early 2020 coincided with a global decrease in active influenza circulation. However, between July and November 2020, an influenza A(H3N2) epidemic occurred in Cambodia and in other neighboring countries in the Greater Mekong Subregion in Southeast Asia. We characterized the genetic and antigenic evolution of A(H3N2) in Cambodia and found that the 2020 epidemic comprised genetically and antigenically similar viruses of Clade3C2a1b/131K/94N, but they were distinct from the WHO recommended influenza A(H3N2) vaccine virus components for 2020–2021 Northern Hemisphere season. Phylogenetic analysis revealed multiple virus migration events between Cambodia and bordering countries, with Laos PDR and Vietnam also reporting similar A(H3N2) epidemics immediately following the Cambodia outbreak: however, there was limited circulation of these viruses elsewhere globally. In February 2021, a virus from the Cambodian outbreak was recommended by WHO as the prototype virus for inclusion in the 2021–2022 Northern Hemisphere influenza vaccine. IMPORTANCE The 2019 coronavirus disease (COVID-19) pandemic has significantly altered the circulation patterns of respiratory diseases worldwide and disrupted continued surveillance in many countries. Introduction of control measures in early 2020 against Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection has resulted in a remarkable reduction in the circulation of many respiratory diseases. Influenza activity has remained at historically low levels globally since March 2020, even when increased influenza testing was performed in some countries. Maintenance of the influenza surveillance system in Cambodia in 2020 allowed for the detection and response to an influenza A(H3N2) outbreak in late 2020, resulting in the inclusion of this virus in the 2021–2022 Northern Hemisphere influenza vaccine.

BACKGROUND: Global influenza virus circulation decreased during the COVID-19 pandemic, possibly due to widespread community mitigation measures. Cambodia eased some COVID-19 mitigation measures in June and July 2020. On 20 August a cluster of respiratory illnesses occurred among residents of a pagoda, including people who tested positive for influenza A but none who were positive for SARS-CoV-2. METHODS: A response team was deployed on 25 August 2020. People with influenza-like illness (ILI) were asked questions regarding demographics, illness, personal prevention measures, and residential arrangements. Respiratory swabs were tested for influenza and SARS-Cov-2 by real-time reverse transcription PCR, and viruses were sequenced. Sentinel surveillance data were analyzed to assess recent trends in influenza circulation in the community. RESULTS: Influenza A (H3N2) viruses were identified during sentinel surveillance in Cambodia in July 2020 prior to the reported pagoda outbreak. Among the 362 pagoda residents, 73 (20.2%) ILI cases were identified and 40 were tested, where 33/40 (82.5%) confirmed positive for influenza A (H3N2). All 40 were negative for SARS-CoV-2. Among the 73 residents with ILI, none were vaccinated against influenza, 47 (64%) clustered in 3/8 sleeping quarters, 20 (27%) reported often wearing a mask, 27 (36%) reported often washing hands, and 11 (15%) reported practicing social distancing. All viruses clustered within clade 3c2.A1 close to strains circulating in Australia in 2020. CONCLUSIONS: Circulation of influenza viruses began in the community following the relaxation of national COVID-19 mitigation measures, and prior to the outbreak in a pagoda with limited social distancing. Continued surveillance and influenza vaccination are required to limit the impact of influenza globally.

The recent apparent increase in human monkeypox cases across a wide geographic area, the potential for further spread, and the lack of reliable surveillance have raised the level of concern for this emerging zoonosis. In November 2017, the World Health Organization (WHO), in collaboration with CDC, hosted an informal consultation on monkeypox with researchers, global health partners, ministries of health, and orthopoxvirus experts to review and discuss human monkeypox in African countries where cases have been recently detected and also identify components of surveillance and response that need improvement. Endemic human monkeypox has been reported from more countries in the past decade than during the previous 40 years. Since 2016, confirmed cases of monkeypox have occurred in Central African Republic, Democratic Republic of the Congo, Liberia, Nigeria, Republic of the Congo, and Sierra Leone and in captive chimpanzees in Cameroon. Many countries with endemic monkeypox lack recent experience and specific knowledge about the disease to detect cases, treat patients, and prevent further spread of the virus. Specific improvements in surveillance capacity, laboratory diagnostics, and infection control measures are needed to launch an efficient response. Further, gaps in knowledge about the epidemiology and ecology of the virus need to be addressed to design, recommend, and implement needed prevention and control measures.

Zika virus infections have been known in Africa and Asia since the 1940s, but the virus's geographic range has expanded dramatically since 2007. Between January 1, 2007, and March 1, 2016, local transmission was reported in an additional 52 countries and territories, mainly in the Americas and the western Pacific, but also in Africa and southeast Asia. Zika virus infections acquired by travelers visiting those countries have been discovered at sites worldwide. Aedes aegypti mosquitoes are the principal vectors, though other mosquito species may contribute to transmission. The virus was found to be neurotropic in animals in experiments conducted in . . .

The prevalence of cataract is higher in developing countries, and in both developed and developing countries more females than males are blind from cataracts. Three epidemiological studies have associated indoor cooking with solid fuels (e.g. wood or dung) and cataract or blindness. However, associations in these studies may have been caused by unmeasured confounding.A hospital-based case-control study was conducted on the Nepal-India border. Cases (n = 206) were women patients, aged 35-75 years with confirmed cataracts. Controls (n = 203), frequency matched by age, were patients attending the refractive error clinic at the same hospital. A standardized questionnaire was administered to all participants. Logistic regression analysis involved adjustment for age, literacy, residential area, ventilation, type of lighting, incense use, and working outside.Compared with using a clean-burning-fuel stove (biogas, LPG, or kerosene), the adjusted odds ratio (OR) for using a flued solid-fuel stove was 1.23 [95% confidence interval (CI) 0.44-3.42], whereas use of an unflued solid-fuel stove had an OR of 1.90 (95% CI 1.00-3.61). Lack of kitchen ventilation was an independent risk factor for cataract (OR 1.96; 95% CI 1.25-3.07).This study provides confirmatory evidence that use of solid fuel in unflued indoor stoves is associated with increased risk of cataract in women who do the cooking. The association is not likely to be due to bias, including confounding, and strengthens the findings of three previous studies. Replacing unflued stoves with flued stoves would greatly reduce this risk, although cooking with cleaner-burning fuels would be the best option.

Many studies have evaluated the role of Cryptosporidium spp. in outbreaks of enteric illness, but few studies have evaluated sporadic cryptosporidiosis in the United States. To assess the risk factors for sporadic cryptosporidiosis among immunocompetent persons, a matched case-control study was conducted in seven sites of the Foodborne Diseases Active Surveillance Network (FoodNet) involving 282 persons with laboratory-identified cryptosporidiosis and 490 age-matched and geographically matched controls. Risk factors included international travel (odds ratio [OR] = 7.7; 95% confidence interval [95% CI] = 2.7 to 22.0), contact with cattle (OR = 3.5; 95% CI = 1.8 to 6.8), contact with persons >2 to 11 years of age with diarrhea (OR = 3.0; 95% CI = 1.5 to 6.2), and freshwater swimming (OR = 1.9; 95% CI = 1.049 to 3.5). Eating raw vegetables was protective (OR = 0.5; 95% CI = 0.3 to 0.7). This study underscores the need for ongoing public health education to prevent cryptosporidiosis, particularly among travelers, animal handlers, child caregivers, and swimmers, and the need for further assessment of the role of raw vegetables in cryptosporidiosis.

PROBLEM: Recent progress in vaccine availability and affordability has raised prospects for reducing death and disability from neurological infections in children. In many Asian countries, however, the epidemiology and public health burden of neurological diseases such as Japanese encephalitis and bacterial meningitis are poorly understood. APPROACH: A sentinel surveillance system for Japanese encephalitis was developed and embedded within the routine meningoencephalitis syndromic surveillance system in Cambodia in 2006. The sentinel surveillance system was designed so surveillance and laboratory testing for other etiologies of neurological infection could be incorporated. LOCAL SETTING: The Communicable Disease Control department of the Ministry of Health in Cambodia worked with partners to establish the sentinel surveillance system. RELEVANT CHANGES: The sentinel surveillance system has provided important information on the disease burden of Japanese encephalitis in Cambodia and is now providing a platform for expansion to incorporate laboratory testing for other vaccine-preventable neurological infections in children. LESSONS LEARNED: Sentinel surveillance systems, when linked to syndromic reporting systems, can characterize the epidemiology of meningoencephalitis and identify the proportion of hospital-based neurological infection in children that is vaccine preventable. Integrated systems enable consistency in data collection, analysis and information dissemination, and they enhance the capacity of public health managers to provide more credible and integrated information to policy-makers. This will assist decision-making about the potential role of immunization in reducing the incidence of childhood neurological infections.

Background In persons with acquired immunodeficiency syndrome (AIDS), Cryptosporidium parvum causes a prolonged, severe diarrheal illness to which there is no effective treatment, and the risk of developing cryptosporidiosis from drinking tap water in non-outbreak settings remains uncertain. To test the hypothesis that drinking tap water was associated with developing cryptosporidiosis, we conducted a matched case-control study among persons with AIDS in San Francisco. Methods Among patients reported to the San Francisco AIDS Registry from May 1996 through September 1998, we compared patients who developed cryptosporidiosis to those who did not. Cases were individually matched to controls based on age, sex, race/ethnicity, CD4+ T lymphocyte count, date of CD4+ count, and date of case diagnosis. Population attributable fractions (PAFs) were calculated. Results The study consisted of 49 cases and 99 matched controls. In the multivariable analysis with adjustments for confounders, tap water consumption inside and outside the home at the highest exposure categories was associated with the occurrence of cryptosporidiosis (inside the home: odds ratio (OR), 6.76; 95% CI 1.37–33.5, and outside the home: OR 3.16; 95% CI 1.23–8.13). The PAF was 85%; that is, the proportion of cases of cryptosporidiosis in San Francisco AIDS patients attributable to tap water consumption could have been as high as 85%. Conclusions Although the results from this observational study cannot be considered definitive, until there is more data, we recommend persons with AIDS, especially those with compromised immune systems, consider avoiding tap water.

We conducted a randomized, triple-blinded home drinking water intervention trial to determine if a large study could be undertaken while successfully blinding participants. Households were randomized 50:50 to use externally identical active or sham treatment devices. We measured the effectiveness of blinding of participants by using a published blinding index in which values >0.5 indicate successful blinding. The principal health outcome measured was "highly credible gastrointestinal illness" (HCGI). Participants (n=236) from 77 households were successfully blinded to their treatment assignment. At the end of the study, the blinding index was 0.64 (95% confidence interval 0.51-0.78). There were 103 episodes of HCGI during 10,790 person-days at risk in the sham group and 82 episodes during 11,380 person-days at risk in the active treatment group. The incidence rate ratio of disease (adjusted for the clustered sampling) was 1.32 (95% CI 0.75, 2.33) and the attributable risk was 0.24 (95% CI -0.33, 0.57). These data confirm that participants can be successfully blinded to treatment group assignment during a randomized trial of an in-home drinking water intervention.