Cryptosporidium species and subtypes identified in human domestic cases through the national microbiological surveillance programme in Sweden from 2018 to 2022.

BACKGROUND: The intestinal protozoan parasite Cryptosporidium is an important cause of diarrheal disease worldwide. A national microbiological surveillance programme was implemented in Sweden in 2018 in order to increase knowledge of the molecular epidemiology of human cryptosporidiosis to better understand transmission patterns and potential zoonotic sources. This article summarises the results of the first five years of the surveillance programme. METHODS: Cryptosporidium-positive faecal and DNA samples from domestically acquired infections were collected from clinical microbiological laboratories in Sweden. Species and subtype determination was performed using 60 kDa glycoprotein and/or small subunit ribosomal RNA gene analysis. RESULTS: Between 2018 and 2022, 1654 samples were analysed and 11 different species were identified: C. parvum (n = 1412), C. mortiferum (n = 59), C. hominis (n = 56), C. erinacei (n = 11), C. cuniculus (n = 5), C. meleagridis (n = 3), C. equi (n = 2), C. ubiquitum (n = 2), and one each of C. canis, C. ditrichi and C. felis. Subtyping revealed seven subtype families of C. parvum (new subtype families IIy and IIz) and 69 different subtypes (11 new subtypes). The most common C. parvum subtypes were IIdA22G1c, IIdA24G1, IIdA15G2R1 and IIaA16G1R1b. For C. hominis, four different subtype families and nine different subtypes (two new subtypes) were identified. For additional species, two new subtype families (IIIk and VId) and nine new subtypes were identified. All successfully subtyped C. mortiferum cases were subtype XIVaA20G2T1, confirming previous findings in Sweden. Several outbreaks were identified of which the majority were foodborne and a few were due to direct contact with infected animals. CONCLUSION: Infection with C. parvum is the leading cause of human cryptosporidiosis acquired in Sweden, where more than 90% of domestic cases are caused by this zoonotic species and only a small proportion of cases are due to infection with other species. The rodent-associated C. mortiferum is considered an emerging zoonotic species in Sweden and the number of domestically acquired human cases has surpassed that of infection with C. hominis. A high diversity of species and subtypes, as well as diversity within the same subtype, was detected. Also, cryptosporidiosis appears to affect adults to a great extent in Sweden.

High Prevalence of SARS-CoV-2 Omicron Infection Despite High Seroprevalence, Sweden, 2022.

We performed 2 surveys during 2022 to estimate point prevalences of SARS-CoV-2 infection compared with overall seroprevalence in Sweden. Point prevalence was 1.4% in March and 1.5% in September. Estimated seroprevalence was >80%, including among unvaccinated children. Continued SARS-CoV-2 surveillance is necessary for detecting emerging, possibly more pathogenic variants.

Cryptosporidium chipmunk genotype I - An emerging cause of human cryptosporidiosis in Sweden.

Most cases of cryptosporidiosis in humans are caused by Cryptosporidium parvum or Cryptosporidium hominis. However, more uncommon species are increasingly being recognised to cause infection in humans. Here we report that Cryptosporidium chipmunk genotype I, which has various rodents as its natural host, is the third most common source of human cryptosporidiosis in Sweden. We also describe the first small outbreak of cryptosporidiosis caused by Cryptosporidium chipmunk genotype I and report the first case of zoonotic transmission of Cryptosporidium chipmunk genotype I from a red squirrel to a human. Cryptosporidium chipmunk genotype I was identified in 20 human cases, including 16 sporadic cases, three outbreak-related cases, and one zoonotic case, as well as in two squirrel samples. Gp60 subtyping which was successful for 19 human cases and two squirrel samples showed that all samples harboured the same subtype, XIVaA20G2T1. The work presented here suggests that red squirrel is a natural host of Cryptosporidium chipmunk genotype I and that infection with Cryptosporidium chipmunk genotype I is an emerging cause of domestic cryptosporidiosis in Sweden and a potential source of outbreaks.

What will studies of Fulani individuals naturally exposed to malaria teach us about protective immunity to malaria?

There are an estimated over 200 million yearly cases of malaria worldwide. Despite concerted international effort to combat the disease, it still causes approximately half a million deaths every year, the majority of which are young children with Plasmodium falciparum infection in sub-Saharan Africa. Successes are largely attributed to malaria prevention strategies, such as insecticide-treated mosquito nets and indoor spraying, as well as improved access to existing treatments. One important hurdle to new approaches for the treatment and prevention of malaria is our limited understanding of the biology of Plasmodium infection and its complex interaction with the immune system of its human host. Therefore, the elimination of malaria in Africa not only relies on existing tools to reduce malaria burden, but also requires fundamental research to develop innovative approaches. Here, we summarize our discoveries from investigations of ethnic groups of West Africa who have different susceptibility to malaria.

From mice to men: Three cases of human infection with Cryptosporidium ditrichi.

Most human cases of cryptosporidiosis are caused by Cryptosporidium parvum or Cryptosporidium hominis. However, the number of recognised Cryptosporidium species, some of which are capable of infecting humans, is continuously increasing. Here we present three human cases infected with Cryptosporidium ditrichi, a recently described species in Apodemus spp. (striped field mouse, yellow-necked mouse, and wood mouse) from various European countries. All three patients were infected in Sweden, but in different years and in different parts of the country. Two patients, from whom clinical data were available, showed symptoms consistent with cryptosporidiosis. For one patient, epidemiological data indicated a possible close contact with mice. The obtained sequences at the small subunit rRNA, actin, and Cryptosporidium oocyst wall protein loci showed 100% identity to C. ditrichi isolates from Apodemus spp., while no 70 kDa heat shock protein gene sequences from C. ditrichi were available for comparison. This study shows the importance of including molecular typing in Cryptosporidium surveillance programmes, and it adds one more species to the plethora of Cryptosporidium spp. hitherto diagnosed in Swedish patients.

Major transcriptional changes observed in the Fulani, an ethnic group less susceptible to malaria.

The Fulani ethnic group has relatively better protection from Plasmodium falciparum malaria, as reflected by fewer symptomatic cases of malaria, lower infection rates, and lower parasite densities compared to sympatric ethnic groups. However, the basis for this lower susceptibility to malaria by the Fulani is unknown. The incidence of classic malaria resistance genes are lower in the Fulani than in other sympatric ethnic populations, and targeted SNP analyses of other candidate genes involved in the immune response to malaria have not been able to account for the observed difference in the Fulani susceptibility to P.falciparum. Therefore, we have performed a pilot study to examine global transcription and DNA methylation patterns in specific immune cell populations in the Fulani to elucidate the mechanisms that confer the lower susceptibility to P.falciparum malaria. When we compared uninfected and infected Fulani individuals, in contrast to uninfected and infected individuals from the sympatric ethnic group Mossi, we observed a key difference: a strong transcriptional response was only detected in the monocyte fraction of the Fulani, where over 1000 genes were significantly differentially expressed upon P.falciparum infection.

Malaria-derived hemozoin exerts early modulatory effects on the phenotype and maturation of human dendritic cells.

Plasmodium falciparum (P. falciparum)-induced effects on the phenotype of human dendritic cells (DC) could contribute to poor induction of long-lasting protective immunity against malaria. DC ability to present antigens to naïve T cells, thus initiating adaptive immune responses depends on complex switches in chemokine receptors, production of soluble mediators and expression of molecules enabling antigen-presentation and maturation. To examine the cellular basis of these processes in the context of malaria, we performed detailed analysis of early events following exposure of human monocyte-derived DC to natural hemozoin (nHZ) and the synthetic analog of its heme core, ß-hematin. DC exposed to either molecule produced high levels of the inflammatory chemokine MCP-1, showed continuous high expression of the inflammatory chemokine receptor CCR5, no upregulation of the lymphoid homing receptor CCR7 and no cytoskeletal actin redistribution with loss of podosomes. DC partially matured as indicated by increased expression of major histocompatibility complex (MHC) class II and CD86 following nHZ and ß-hematin exposure, however there was a lack in expression of the maturation marker CD83 following nHZ but not ß-hematin exposure. Overall our data demonstrate that exposure to nHZ partially impairs the capacity of DC to mature, an effect in part differential to ß-hematin.

Large differences in prevalence of Pfcrt and Pfmdr1 mutations between Mwanza, Tanzania and Iganga, Uganda-a reflection of differences in policies regarding withdrawal of chloroquine?

BACKGROUND: Malaria is still a major public health problem in the world and sub-Saharan Africa is one of the most affected areas. Efforts to control malaria are highly affected by drug resistance to commonly used antimalarials. The introduction of artemisinin based combination therapy (ACT) as a first line drug seems to be a major step in treatment of uncomplicated malaria, though search for drugs to combine with artemisinins still continues. There have been reports on increased prevalence of the wild type markers Pfcrt 76K and Pfmdr1 86N in some African countries and ideas of using chloroquine (CQ) in intermittent presumptive treatment for adults (IPTa) is coming up. The common combination of artemether and lumefantrine even selects for parasites that are wild type at these positions. This study is comparing prevalence of mutation at these two positions in two East African countries with ACT as their first line drug but following somewhat different drug policies regarding CQ. In Tanzania CQ was stopped in 2001 but in Uganda CQ was retained in combination with sulfadoxine-pyrimethamine (SP) and used in home based management of fever for some time. SP is still used in IPT for pregnant women. METHODS: Blood smears and dried blood spots on Whatman filter papers were collected from 100 patients with uncomplicated malaria in Mwanza, Tanzania and 100 patients from Iganga, Uganda. DNA was extracted from all samples using Tris EDTA method. PCR and RFLP were performed and sequencing done on Pfcrt amplification products. RESULTS: The prevalence of K76T mutations at Pfcrt in samples from Mwanza, Tanzania was 40.5% (34/84) and 100% (100/100) in samples from Iganga, Uganda. Prevalence of N86Y mutations in Pfmdr1 was 16.9% (13/77) and 77.7% (63/81) in samples from Mwanza and Iganga, respectively. The re-emergence of CQ sensitive isolates in Mwanza, Tanzania showed the haplotype CVMNK typical for wild type isolates. CONCLUSIONS: The prevalence of CQ resistant parasites in Mwanza, Tanzania is low compared to the existing high level of resistant parasites in Iganga, Uganda. This could be an indication that CQ may become useful in the future in Tanzania. This study shows clearly that there is a difference in mutations at these positions in these two countries implementing similar but somewhat different drug policies. In Uganda the drug resistance has reached fixation while in Tanzania the prevalence is going down.

IDOMAL: an ontology for malaria.

BACKGROUND: Ontologies are rapidly becoming a necessity for the design of efficient information technology tools, especially databases, because they permit the organization of stored data using logical rules and defined terms that are understood by both humans and machines. This has as consequence both an enhanced usage and interoperability of databases and related resources. It is hoped that IDOMAL, the ontology of malaria will prove a valuable instrument when implemented in both malaria research and control measures. METHODS: The OBOEdit2 software was used for the construction of the ontology. IDOMAL is based on the Basic Formal Ontology (BFO) and follows the rules set by the OBO Foundry consortium. RESULTS: The first version of the malaria ontology covers both clinical and epidemiological aspects of the disease, as well as disease and vector biology. IDOMAL is meant to later become the nucleation site for a much larger ontology of vector borne diseases, which will itself be an extension of a large ontology of infectious diseases (IDO). The latter is currently being developed in the frame of a large international collaborative effort. CONCLUSIONS: IDOMAL, already freely available in its first version, will form part of a suite of ontologies that will be used to drive IT tools and databases specifically constructed to help control malaria and, later, other vector-borne diseases. This suite already consists of the ontology described here as well as the one on insecticide resistance that has been available for some time. Additional components are being developed and introduced into IDOMAL.