In a survey of household cats and dogs of laboratory-confirmed COVID-19 patients, we found a high seroprevalence of SARS-CoV-2 antibodies, ranging from 21% to 53%, depending on the positivity criteria chosen. Seropositivity was significantly greater among pets from COVID-19+ households compared to those with owners of unknown status. Our results highlight the potential role of pets in the spread of the epidemic.

BackgroundRelapsing fever is the most frequent bacterial disease in Africa. Four main vector / pathogen complexes are classically recognized, with the louse Pediculus humanus acting as vector for B. recurrentis and the soft ticks Ornithodoros sonrai, O. erraticus and O. moubata acting as vectors for Borrelia crocidurae, B. hispanica and B. duttonii, respectively. Our aim was to investigate the epidemiology of the disease in West, North and Central Africa.Methods And FindingsFrom 2002 to 2012, we conducted field surveys in 17 African countries and in Spain. We investigated the occurrence of Ornithodoros ticks in rodent burrows in 282 study sites. We collected 1,629 small mammals that may act as reservoir for Borrelia infections. Using molecular methods we studied genetic diversity among Ornithodoros ticks and Borrelia infections in ticks and small mammals. Of 9,870 burrows investigated, 1,196 (12.1%) were inhabited by Ornithodoros ticks. In West Africa, the southern and eastern limits of the vectors and Borrelia infections in ticks and small mammals were 13°N and 01°E, respectively. Molecular studies revealed the occurrence of nine different Ornithodoros species, including five species new for science, with six of them harboring Borrelia infections. Only B. crocidurae was found in West Africa and three Borrelia species were identified in North Africa: B. crocidurae, B. hispanica, and B. merionesi.Conclusions Borrelia Spirochetes responsible for relapsing fever in humans are highly prevalent both in Ornithodoros ticks and small mammals in North and West Africa but Ornithodoros ticks seem absent south of 13°N and small mammals are not infected in these regions. The number of Ornithodoros species acting as vector of relapsing fever is much higher than previously known.

The origin of Plasmodium falciparum in South America is controversial. Some studies suggest a recent introduction during the European colonizations and the transatlantic slave trade. Other evidence—archeological and genetic—suggests a much older origin. We collected and analyzed P. falciparum isolates from different regions of the world, encompassing the distribution range of the parasite, including populations from sub-Saharan Africa, the Middle East, Southeast Asia, and South America. Analyses of microsatellite and SNP polymorphisms show that the populations of P. falciparum in South America are subdivided in two main genetic clusters (northern and southern). Phylogenetic analyses, as well as Approximate Bayesian Computation methods suggest independent introductions of the two clusters from African sources. Our estimates of divergence time between the South American populations and their likely sources favor a likely introduction from Africa during the transatlantic slave trade.

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Recent molecular exploration of the Plasmodium species circulating in great apes in Africa has revealed the existence of a large and previously unknown diversity of Plasmodium. For instance, gorillas were found to be infected by parasites closely related to Plasmodium falciparum, suggesting that the human malignant malaria agent may have arisen after a transfer from gorillas. Although this scenario is likely in light of the data collected in great apes, it remained to be ascertained whether P. falciparum-related parasites may infect other nonhuman primates in Africa. Using molecular tools, we here explore the diversity of Plasmodium species infecting monkeys in Central Africa. In addition to previously described Hepatocystis and Plasmodium species (Plasmodium gonderi and Plasmodium sp DAJ-2004), we have found one African monkey to be infected by a P. falciparum-related parasite. Examination of the nuclear and mitochondrial genomes of this parasite reveals that it is specific of nonhuman primates, indicating that P. falciparum-related pathogens can naturally circulate in some monkey populations in Africa. We also show that at least two distinct genetic entities of P. falciparum infect nonhuman primates and humans, respectively. Our discoveries bring into question the proposed gorilla origin of human P. falciparum.human malaria | laverania clade | parasite host transfer | cytochrome b | biological evolution U ntil very recently, only one species (Plasmodium reichenowi) was known to be a phylogenetic sister lineage of Plasmodium falciparum, the agent of malignant human malaria. These two species were the only known representatives of the subgenus Laverania (1). In 2009 and 2010, several studies have revealed the existence of a number of distinct phylogenetic species belonging to this subgenus and infecting chimpanzees, bonobos, and gorillas in Africa (2-6), drastically modifying our understanding of the evolution of the Laverania lineage, and P. falciparum in particular (7).Liu et al. (4) have proposed that the human strains of P. falciparum arose after a single gorilla-to-human transmission (4, 7). This scenario is based on the discovery of P. falciparum-related strains naturally circulating in lowland gorillas (2, 4, 6) that display greater genetic diversity than human strains (4). In contrast, no P. falciparum strains were found in wild chimpanzees or bonobos despite similar sampling efforts (4). Strains of P. falciparum had been found only in chimpanzees and bonobos living either in captivity or sanctuaries, with the possibility of a crossspecies infection from humans to them (2, 3). It, however, remains possible that P. falciparum-related strains circulate in wild chimpanzees and bonobos at a lower prevalence than in gorillas (8) and/or in geographic areas not yet explored. Given the propensity of Plasmodium parasites to switch hosts (e.g., the transfer of P. knowlesi from macaques to humans (9) and P. vivax and P. malariae between humans and New World monkeys; ref. 10), one cannot exclude that P. falciparum-r...

Recent studies have highlighted the large diversity of malaria parasites infecting African great apes (subgenus Laverania) and their strong host specificity. Although the existence of genetic incompatibilities preventing the cross-species transfer may explain host specificity, the existence of vectors with a high preference for a determined host represents another possibility. To test this hypothesis, we undertook a 15-mo-long longitudinal entomological survey in two forest regions of Gabon, where wild apes live, at different heights under the canopy. More than 2,400 anopheline mosquitoes belonging to 18 species were collected. Among them, only three species of Anopheles were found infected with ape Plasmodium: Anopheles vinckei, Anopheles moucheti, and Anopheles marshallii. Their role in transmission was confirmed by the detection of the parasites in their salivary glands. Among these species, An. vinckei showed significantly the highest prevalence of infection and was shown to be able to transmit parasites of both chimpanzees and gorillas. Transmission was also shown to be conditioned by seasonal factors and by the heights of capture under the canopy. Moreover, human landing catches of sylvan Anopheles demonstrated the propensity of these three vector species to feed on humans when available. Our results suggest therefore that the strong host specificity observed in the Laveranias is not linked to a specific association between the vertebrate host and the vector species and highlight the potential role of these vectors as bridge between apes and humans.Plasmodium | Laverania | Anopheles | ape-to-human infection | African rainforest R ecent studies on great apes in Africa have revealed the existence of a large diversity of Plasmodium parasites infecting chimpanzees and gorillas, some being related to the most deadly human parasite Plasmodium falciparum (subgenus Laverania), others to the human parasites Plasmodium malariae, Plasmodium ovale, or Plasmodium vivax (subgenus Plasmodium) (1-4).Within the subgenus Laverania, eight species are currently recognized. Among them, four species (Plasmodium reichenowi, Plasmodium gaboni, Plasmodium billcollinsi, and Plasmodium billbrayi) were observed only in chimpanzees and three (Plasmodium praefalciparum, Plasmodium adleri, and Plasmodium blacklocki) only in gorillas (2,3,5). In this subgenus, only P. falciparum infects humans. In natura, although these different host species cooccur in the same habitat where their ranges overlap, no transfer of Laverania parasites was ever documented between humans and apes or between gorillas and chimpanzees despite large sampling efforts (2, 3, 6). Similarly, ancient reciprocal transplant experiments of Laverania parasites between humans and apes (mostly chimpanzees) failed to produce infections (5). On the contrary, for parasites of the subgenus Plasmodium, like P. vivax or P. malariae, transfers were documented in natural populations (2, 4, 7) or during experimental infections (5). All this suggests therefore a strong host specifici...

The first two authors contributed equally to the study.We explored associations between the common protozoan parasite Toxoplasma gondii and brain cancers in human populations. We predicted that T. gondii could increase the risk of brain cancer because it is a long-lived parasite that encysts in the brain, where it provokes inflammation and inhibits apoptosis. We used a medical geography approach based on the national incidence of brain cancers and seroprevalence of T. gondii. We corrected reports of incidence for national gross domestic product because wealth probably increases the ability to detect cancer. We also included gender, cell phone use and latitude as variables in our initial models. Prevalence of T. gondii explained 19 per cent of the residual variance in brain cancer incidence after controlling for the positive effects of gross domestic product and latitude among nations. Infection with T. gondii was associated with a 1.8-fold increase in the risk of brain cancers across the range of T. gondii prevalence in our dataset (4 -67%). These results, though correlational, suggest that T. gondii should be investigated further as a possible oncogenic pathogen of humans.

Sickle cell disease (SCD) is a genetic disorder that poses a serious health threat in tropical Africa, which the World Health Organization has declared a public health priority. Its persistence in human populations has been attributed to the resistance it provides to Plasmodium falciparum malaria in its heterozygous state, called sickle cell trait (SCT). Because of migration, SCT is becoming common outside tropical countries: It is now the most important genetic disorder in France, affecting one birth for every 2,400, and one of the most common in the United States. We assess the strength of the association between SCT and malaria, using current data for both SCT and malaria infections. A total of 3,959 blood samples from 195 villages distributed over the entire Republic of Gabon were analyzed. Hemoglobin variants were identified by using HPLCy (HPLC). Infections by three species of Plasmodium were detected by PCR followed by sequencing of a 201-bp fragment of cytochrome b. An increase of 10% in P. falciparum malaria prevalence is associated with an increase by 4.3% of SCT carriers. An increase of 10 y of age is associated with an increase by 5.5% of SCT carriers. Sex is not associated with SCT. These strong associations show that malaria remains a selective factor in current human populations, despite the progress of medicine and the actions undertaken to fight this disease. Our results provide evidence that evolution is still present in humans, although this is sometimes questioned by scientific, political, or religious personalities.sickle cell disease | Plasmodium falciparum | human evolution | Gabon | natural selection