OBJECTIVE: To examine the impact of COVID-19 pandemic on the epidemic status of imported malaria and national malaria control program in China, so as to provide insights into post-elimination malaria surveillance. METHODS: All data pertaining to imported malaria cases were collected from Anhui Province, Hubei Province, Henan Province, Zhejiang Province and Guangxi Zhuang Autonomous Region during the period from January 1, 2018 through December 31, 2021. The number of malaria cases, species of malaria parasites, country where malaria parasite were infected, diagnosis and treatment after returning to China, and response were compared before (from January 1, 2018 to January 22, 2020) and after the COVID-19 pandemic (from January 23, 2020 to December 31, 2021). RESULTS: A total of 2 054 imported malaria cases were reported in Anhui Province, Hubei Province, Henan Province, Zhejiang Province and Guangxi Zhuang Autonomous Region during the period from January 1, 2018 to December 31, 2021, and there were 1 722 cases and 332 cases reported before and after the COVID-19 pandemic, respectively. All cases were reported within one day after definitive diagnosis. The annual mean number of reported malaria cases reduced by 79.30% in Anhui Province, Hubei Province, Henan Province, Zhejiang Province and Guangxi Zhuang Autonomous Region after the COVID-19 pandemic (171 cases) than before the pandemic (826 cases), and the number of monthly reported malaria cases significantly reduced in Anhui Province, Hubei Province, Henan Province, Zhejiang Province and Guangxi Zhuang Autonomous Region since February 2020. There was a significant difference in the constituent ratio of species of malaria parasites among the imported malaria cases in Anhui Province, Hubei Province, Henan Province, Zhejiang Province and Guangxi Zhuang Autonomous Region before and after the COVID-19 pandemic (χ² = 146.70, P < 0.05), and P. falciparum malaria was predominant before the COVID-19 pandemic (72.30%), while P. ovale malaria (44.28%) was predominant after the COVID-19 pandemic, followed by P. falciparum malaria (37.65%). There was a significant difference in the constituent ratio of country where malaria parasites were infected among imported malaria cases in Anhui Province, Hubei Province, Henan Province, Zhejiang Province and Guangxi Zhuang Autonomous Region before and after the COVID-19 pandemic (χ² = 13.83, P < 0.05), and the proportion of malaria cases that acquired Plasmodium infections in western Africa reduced after the COVID-19 pandemic that before the pandemic (44.13% vs. 37.95%; χ² = 4.34, P < 0.05), while the proportion of malaria cases that acquired Plasmodium infections in eastern Africa increased after the COVID-19 pandemic that before the pandemic (9.58% vs. 15.36%; χ² = 9.88, P = 0.02). The proportion of completing case investigation within 3 days was significantly lower after the COVID-19 pandemic than before the pandemic (96.69% vs. 98.32%; χ²= 3.87, P < 0.05), while the proportion of finishing foci investigation and response within 7 days was significantly higher after the COVID-19 pandemic than before the pandemic (100.00% vs. 98.43%; χ² = 3.95, P < 0.05). CONCLUSIONS The number of imported malaria cases remarkably reduced in Anhui Province, Hubei Province, Henan Province, Zhejiang Province and Guangxi Zhuang Autonomous Region of China during the COVID-19 pandemic, with a decreased proportion of completing case investigations within 3 days. The sensitivity of the malaria surveillance-response system requires to be improved to prevent the risk of secondary transmission of malaria due to the sharp increase in the number of imported malaria cases following the change of the COVID-19 containment policy.
Humans ; Pandemics ; China/epidemiology* ; Incidence ; COVID-19/epidemiology* ; Malaria/prevention & control* ; Malaria, Falciparum/epidemiology*

Detailed description of malaria in low transmission areas is crucial for elimination. The current study aimed to provide a comprehensive description for malaria transmission in Jazan, a low transmission district, southwestern Saudi Arabia. Patients at a tertiary care hospital were recruited in our study between August 2016 and September 2018. Malaria diagnosis was performed through a species-specific nested polymerase chain reaction (nested PCR), microscopy and Paramax-3™ rapid detection test (RDT). Malaria was detected in 30 patients by the PCR, with point prevalence of 10.9%. Of these malaria infections, 80% was imported, 26.6% was asymptomatic and 23.3% was sub-microscopic. Malaria was reported throughout the year, with February/March and September/October peaks. Infection was significantly more in males than in females (P=0.01). Likewise, infections were detected more in febrile than in non-febrile patients (P=0.01). Adult aged 15–24 years, fever and travel were identified as high-risk factors. Malaria was primarily attributed to Plasmodium falciparum mono-infections, followed by P. vivax mono-infections and lastly to falciparum/vivax mixed infections accounting 76.6%, 16.6%, and 6.6% of PCR-confirmed malaria cases, respectively. The nested PCR was superior to the smear microscopy (sensitivity 76.6%; specificity 100%) and the RDT (sensitivity 83.3%, specificity 94.2%). The overall percent agreement between microscopy and the RDT was 92.7% (kappa=0.63). High proportion of imported malaria including sub-microscopic and sub-patent cases were described. We suggest that incorporation of molecular tool into the conventional malaria diagnosis is beneficial in Jazan district.
Adult ; Coinfection ; Diagnosis ; Female ; Fever ; Humans ; Malaria ; Male ; Microscopy ; Plasmodium falciparum ; Polymerase Chain Reaction ; Prevalence ; Saudi Arabia ; Sensitivity and Specificity ; Tertiary Healthcare

Indonesia and South Korea have become inseparable in various respects since the 2 countries established diplomatic relation in 1973. Indonesia is a tropical region that stretches across the equator, comprised of 5 main islands (Java, Kalimantan, Sumatra, Sulawesi, and Papua) and 4 archipelagoes (Riau, Bangka Belitung, Nusa Tenggara, and Maluku). As most population of Eastern Indonesia (Sulawesi, Papua and Nusa Tenggara & Maluku) live in poor areas, it is expected that there will be many parasites. Nevertheless, little is known about the status of parasites in Indonesia. This study examines the prevalences of malaria and lymphatic filaria, which are prevalent in Indonesia, as well as those of soil-transmitted-helminths (STH). As a result, the Plasmodium falciparum and P. vivax case loads are almost equal. The current prevalence of P. vivax is uniformly low (<5%) in all age groups and annual parasite incidence (API) showed decreasing tendency as 0.84 per 1,000 population in 2016. However, more than 65 million people still live in malaria epidemic regions. Lymphatic filariasis remains an important public health problem and 236 cities were classified as endemic areas in 514 cities/districts in 2017. It is difficult to ascertain the current prevalence rate of STH in Indonesia, although West Sumba and Southwest Sumba in East Nusa Tenggara reported prevalence rate of more than 20%. The study also considers the (sero) prevalences of other parasites identified in Indonesia. This report should be useful not only to parasitologists but also to travelers and people with business in Indonesia.
Commerce ; Diplomacy ; Elephantiasis, Filarial ; Humans ; Incidence ; Indonesia ; Islands ; Korea ; Malaria ; Parasites ; Plasmodium falciparum ; Prevalence ; Public Health

Mixed-species malaria infections are often unrecognized or underestimated. We hereby report the first described case of mixed infection with Plasmodium falciparum and Plasmodium ovale malaria in a returned traveller in Korea. In August 2016, a 25-year-old returned traveller from Cameroon and Democratic Republic of Congo presented with fever. He was diagnosed as P. falciparum malaria and successfully treated with artesunate. And 5 weeks after the completion of treatment, he presented with fever and diagnosed as P. ovale infection. P. ovale infection is a rare cause of malaria and often shows delayed presentation due to its dormant liver stage as hypnozoites. At re-presentation, the immunochromatographic test and microscopic examinations of our patient did not reveal P. ovale, which was only detected via polymerase chain reaction (PCR) assay. This case highlights the importance of considering malaria infection even in persons who have previously received malaria treatment. It also shows the usefulness of PCR testing for diagnosing P. ovale infections, which often present with a low level of parasitaemia.
Adult ; Cameroon ; Coinfection* ; Congo ; Fever ; Humans ; Korea* ; Liver ; Malaria ; Plasmodium falciparum* ; Plasmodium ovale* ; Plasmodium* ; Polymerase Chain Reaction

Molecular techniques have been introduced for malaria diagnosis because they offer greater sensitivity and specificity than microscopic examinations. Therefore, DNA isolation methods have been developed for easy preparation and cost effectiveness. The present study described a simple protocol for Plasmodium DNA isolation from EDTA-whole blood. This study demonstrated that after heating infected blood samples with Tris–EDTA buffer and proteinase K solution, without isolation and purification steps, the supernatant can be used as a DNA template for amplification by PCR. The sensitivity of the extracted DNA of Plasmodium falciparum and Plasmodium vivax was separately analyzed by both PCR and semi-nested PCR (Sn-PCR). The results revealed that for PCR the limit of detection was 40 parasites/μl for P. falciparum and 35.2 parasites/μl for P. vivax, whereas for Sn-PCR the limit of detection was 1.6 parasites/μl for P. falciparum and 1.4 parasites/μl for P. vivax. This new method was then verified by DNA extraction of whole blood from 11 asymptomatic Myanmar migrant workers and analyzed by Sn-PCR. The results revealed that DNA can be extracted from all samples, and there were 2 positive samples for Plasmodium (P. falciparum and P. vivax). Therefore, the protocol can be an alternative method for DNA extraction in laboratories with limited resources and a lack of trained technicians for malaria diagnosis. In addition, this protocol can be applied for subclinical cases, and this will be helpful for epidemiology and control.
Cost-Benefit Analysis ; Diagnosis ; DNA ; Edetic Acid ; Endopeptidase K ; Epidemiology ; Heating ; Hot Temperature ; Humans ; Limit of Detection ; Malaria ; Methods ; Myanmar ; Plasmodium falciparum ; Plasmodium vivax ; Plasmodium ; Polymerase Chain Reaction ; Sensitivity and Specificity ; Transients and Migrants

Development of an effective vaccine is critically needed for the prevention of malaria. One of the key antigens for malaria vaccines is the apical membrane antigen 1 (AMA-1) of the human malaria parasite Plasmodium falciparum, the surface protein for erythrocyte invasion of the parasite. The gene encoding AMA-1 has been sequenced from populations of P. falciparum worldwide, but the haplotype diversity of the gene in P. falciparum populations in the Greater Mekong Subregion (GMS), including Thailand, remains to be characterized. In the present study, the AMA-1 gene was PCR amplified and sequenced from the genomic DNA of 65 P. falciparum isolates from 5 endemic areas in Thailand. The nearly full-length 1,848 nucleotide sequence of AMA-1 was subjected to molecular analyses, including nucleotide sequence diversity, haplotype diversity and deduced amino acid sequence diversity and neutrality tests. Phylogenetic analysis and pairwise population differentiation (F( st) indices) were performed to infer the population structure. The analyses identified 60 single nucleotide polymorphic loci, predominately located in domain I of AMA-1. A total of 31 unique AMA-1 haplotypes were identified, which included 11 novel ones. The phylogenetic tree of the AMA-1 haplotypes revealed multiple clades of AMA-1, each of which contained parasites of multiple geographical origins, consistent with the F(st) indices indicating genetic homogeneity or gene flow among geographically distinct populations of P. falciparum in Thailand's borders with Myanmar, Laos and Cambodia. In summary, the study revealed novel haplotypes and population structure needed for the further advancement of AMA-1-based malaria vaccines in the GMS.
Amino Acid Sequence ; Base Sequence ; Cambodia ; DNA ; Erythrocytes ; Gene Flow ; Haplotypes ; Humans ; Laos ; Malaria ; Malaria Vaccines ; Membranes ; Myanmar ; Parasites ; Plasmodium falciparum ; Plasmodium ; Polymerase Chain Reaction ; Polymorphism, Genetic ; Thailand ; Trees

The incidence of vector-borne diseases has increased with climate change and developments of transportation. Malaria was eliminated in the early 1980s in Korea, but one domestic case was reported in 1993. The number of patients increased to 4,142 in 2002, and less than 700 cases of malaria are reported annually nowadays. Additionally, approximately 70 to 80 imported malaria cases were reported annually, and most of them are Plasmodium falciparum infections from Africa. Annually, 20 to 40 cases of Japanese encephalitis are reported, and the incidence is high in individuals between the ages of 40 and 59. Moreover, 313 cases of dengue fever were imported in 2016, and most of them were from Southeast Asia. In 2016, 11,000 cases of scrub typhus were reported, and most of the patients were older than 50. The number of reported cases of severe fever with thrombocytopenia syndrome has been increasing since 2013, mostly in patients older than 60. It is important to avoid vectors for the prevention, and for the doctors to diagnose the apatients as soon as possible.
Africa ; Asia, Southeastern ; Climate Change ; Dengue ; Encephalitis, Japanese ; Fever ; Humans ; Incidence ; Korea ; Malaria ; Plasmodium falciparum ; Scrub Typhus ; Thrombocytopenia ; Transportation

Blackwater fever is a serious clinical syndrome manifested by acute intravascular hemolysis, fever, and the passage of black or red urine, which is classically associated with falciparum malaria and irregular administration of quinine. In Korea, Plasmodium vivax is the only endemic malaria circulating; a number of imported cases of falciparum malaria have been reported in patients following return from international travel to a malaria endemic area. Therefore, it is important for health care professionals including pediatricians to be aware of the falciparum malaria and its clinical courses. Herein, we report a case of a 14-year-old girl with severe falciparum malaria that was complicated by blackwater fever.
Adolescent ; Blackwater Fever* ; Child* ; Delivery of Health Care ; Female ; Fever ; Hemolysis ; Humans ; Korea ; Malaria* ; Malaria, Falciparum ; Plasmodium vivax ; Quinine

As endemic malaria is not commonly seen in the United States, most of the cases diagnosed and reported are associated with travel to and from the endemic places of malaria. As the number of imported cases of malaria has been increasing since 1973, it is important to look into these cases to study the morbidity and mortality associated with this disease in the United States. In this study, we would like to share our experience in diagnosing and treating these patients at our institution. We did a retrospective chart review of 37 cases with a documented history of imported malaria from 1998 to 2012. Among them, 16 patients had complicated malaria during that study period, with a mean length of hospital stay of 3.5 days. Most common place of travel was Africa, and chemoprophylaxis was taken by only 11% of patients. Travel history plays a critical role in suspecting the diagnosis and in initiating prompt treatment.
Africa ; Chemoprevention ; Diagnosis ; Hospitals, Teaching* ; Humans ; Length of Stay ; Malaria* ; Mortality ; Plasmodium falciparum ; Plasmodium vivax ; Retrospective Studies ; United States ; Washington*

In the era of (pre) elimination setting, the prevalence of malaria has been decreasing in most of the previously endemic areas. Therefore, effective cost- and time-saving validated pooling strategy is needed for detection of malaria in low transmission settings. In this study, optimal pooling numbers and lowest detection limit were assessed using known density samples prepared systematically, followed by genomic DNA extraction and nested PCR. Pooling strategy that composed of 10 samples in 1 pool, 20 µl in 1 sample, was optimal, and the parasite density as low as 2 p/µl for both falciparum and vivax infection was enough for detection of malaria. This pooling method showed effectiveness for handling of a huge number of samples in low transmission settings (<9% positive rate). The results indicated that pooling of the blood samples before DNA extraction followed by usual nested PCR is useful and effective for detection of malaria in screening of hidden cases in low-transmission settings.
DNA* ; Limit of Detection ; Malaria* ; Mass Screening ; Methods ; Parasites ; Plasmodium falciparum ; Plasmodium vivax ; Polymerase Chain Reaction ; Prevalence