Comments on “Detection of Toxoplasma gondii in Raw Caprine, Ovine, Buffalo, Bovine, and Camel Milk Using Cell Cultivation, Cat Bioassay, Capture ELISA, and PCR Methods in Iran”

Toxoplasmosis in Human and Animals Around the World. Diagnosis and Perspectives in the One Health Approach

Toxoplasmosis is a unique health disease that significantly affects the health of humans, domestic animals, wildlife and is present in ecosystems, including water, soil and food. Toxoplasma gondii is one of the best-adapted parasites in the word. This parasite is able to persist for long periods in its hosts, in different geographic regions of the word. This review summarizes the current literature of these themes, focusing on: (1) toxoplasmosis, a zoonotic infection; (2) One health approach and toxoplasmosis; (3) human toxoplasmosis; (4) animal toxoplasmosis; (5) toxoplasmosis diagnosis, as immunological, parasitological and molecular diagnosis; (6) T. gondii outbreaks caused by infected meat, milk and dairy products, as well as, vegetables and water consume; (7) studies in experimental models; (8) genetic characterization of T. gondii strains; (9) extracellular vesicles and miRNA; and (10) future perspectives on T. gondii and toxoplasmosis. The vast prevalence of toxoplasmosis in both humans and animals and the dispersion and resistence of T. gondii parasites in environment highlight the importance of the one health approach in diagnostic and control of the disease. Here the different aspects of the one health approach are presented and discussed.

Apicomplexan Protozoa Responsible for Reproductive Disorders: Occurrence of DNA in Blood and Milk of Donkeys (Equus asinus) and Minireview of the Related Literature

Donkeys may be susceptible to many pathological agents and may act as carriers of pathogens for other animal species and humans. This study evaluated the occurrence of potentially abortifacient apicomplexan protozoa DNA in blood and milk samples collected at different time periods during lactation (1, 6, and 10 months) from 33 healthy dairy jennies. A total of 73 blood and 73 milk samples were used for DNA extraction and analysis. Blood specimens from 11/33 (33%) jennies scored positive for Theileria equi, while milk samples scored negative. Blood and milk of 3/33 jennies yielded DNA of Toxoplasma gondii at 6 months (n. 1) and 10 months (n. 2) after parturition. Neospora caninum DNA was found in four milk and in five blood samples only at one month after parturition. This study is the first report about the presence of N. caninum DNA in milk of naturally infected jennies. Moreover, the excretion of N. caninum DNA in some of these jennies at 30 days from the parturition may suggest a possible occurrence of an endogenous cycle, while the presence of T. gondii DNA in the milk collected at 6 and 10 months after parturition may be suggestive of a discontinuous excretion.

Public Health Significance of Toxoplasma gondii Infections in Cattle: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. The ingestion of food or water contaminated with oocysts excreted by infected cats or ingesting uncooked or undercooked meat containing tissue cysts of T. gondii are the 2 major modes of transmission of T. gondii. Viable T. gondii is more prevalent in pork and lamb than in beef. In the past decade, there have been many articles on the high seroprevalence in cattle, particularly from China. There is a report of an outbreak of acute toxoplasmosis in humans suspected to be linked to the ingestion of Artisan fresh cheese from cow's milk. There are conflicting reports concerning the rate of congenital transmission of T. gondii in cattle, especially from Brazil. In a report from Brazil, viable T. gondii was isolated from the blood of 1 of 60 pregnant cows slaughtered at an abattoir and from 1 fetus. The role of beef in the epidemiology of T. gondii infections is still not clear. Here, we review prevalence, persistence of infection, clinical disease, epidemiology, and public health risks of T. gondii infections in cattle from beef and cow's milk worldwide for the past decade.

Public health and economic importance of Toxoplasma gondii infections in goats: The last decade

Toxoplasma gondii infections are common in humans and animals worldwide. Toxoplasmosis in goats continues to be of public health and economic concern. The present review summarizes worldwide information on the prevalence of clinical and subclinical infections, epidemiology, diagnosis, treatment, and genetic diversity of T. gondii in goats in the past decade. There is debate and uncertainty regarding excretion of T. gondii in milk and the ingestion of raw milk as sources of T. gondii infection for humans. Toxoplasmosis can cause abortion and deaths even in adult goats. PCR-RFLP typing of T. gondii DNA derived from viable T. gondii isolates has revealed genetic diversity in goats in North and South America. The significance of T. gondii isolates in domestic goats usually associated with wildlife in USA is discussed. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.

Toxoplasma gondii infection and toxoplasmosis in farm animals: Risk factors and economic impact

The protozoan parasite Toxoplasma gondii is a zoonotic parasite that can be transmitted from animals to humans. Felids, including domestic cats, are definitive hosts that can shed oocysts with their feces. In addition to infections that occur by accidental oral uptake of food or water contaminated with oocysts, it is assumed that a large proportion of affected humans may have become infected by consuming meat or other animal products that contained infective parasitic stages of T. gondii. Since farm animals represent a direct source of infection for humans, but also a possible reservoir for the parasite, it is important to control T. gondii infections in livestock. Moreover, T. gondii may also be pathogenic to livestock where it could be responsible for considerable economic losses in some regions and particular farming systems, e.g. in areas where the small ruminant industry is relevant. This review aims to summarize actual knowledge on the prevalence and effects of infections with T. gondii in the most important livestock species and on the effects of toxoplasmosis on livestock. It also provides an overview on potential risk factors favoring infections of livestock with T. gondii. Knowledge on potential risk factors is prerequisite to implement effective biosecurity measures on farms to prevent T. gondii infections. Risk factors identified by many studies are cat-related, but also those associated with a potential contamination of fodder or water, and with access to a potentially contaminated environment. Published information on the costs T. gondii infections cause in livestock production, is scarce. The most recent peer reviewed reports from Great Britain and Uruguay suggest annual cost of about 5-15 million US $ per country. Since these estimates are outdated, future studies are needed to estimate the present costs due to toxoplasmosis in livestock. Further, the fact that T. gondii infections in livestock may affect human health needs to be considered and the respective costs should also be estimated, but this is beyond the scope of this article.

Toxoplasma gondii infection and food consumption: A systematic review and meta-analysis of case-controlled studies

BACKGROUND

Toxoplasmosis is a zoonotic disease causing severe symptoms in pregnant women and immunocompromised individuals. On average, worldwide, around 30% of people are seropositive. The oral transmission route is of great significance and food, particularly meat, is an important transmission vehicle for T. gondii. However, the role of different food matrices is debated.

OBJECTIVES

The aim of this review was to assess the risk of humans developing acute T. gondii infection via the foodborne route.

STUDY ELIGIBILITY CRITERIA

Case-control studies including acute cases of T. gondii infection were included after literature searches, without time limits, in several databases. All studies estimating the risk of acquiring T. gondii infection after consumption of specific food categories were included.

RESULTS

Three risk factors proved to be significantly associated with acute T. gondii infection in humans: consumption of raw/undercooked meat, Odds Ratio (OR) 3.44 (1.29-9.16), consumption of raw/undercooked beef, OR 2.22 (1.57-3.12), and consumption of raw/undercooked sheep meat, OR 3.85 (1.85-8.00). Consumption of raw/undercooked pork, raw eggs, and unpasteurized milk proved to be non-significant risk factors.

LIMITATIONS

Limitations in the present review and meta-analysis are due to the low number of case-control studies available for analysis and the lack of a search strategy targeting gray literature.

CONCLUSION

Consumption of raw/undercooked beef and sheep meat are important risk factors for T. gondii infection. Their consumption should be avoided in order to prevent toxoplasmosis, particularly by those in at-risk categories, including pregnant women. The review protocol is registered in PROSPERO database (CRD42016043295).

Toxoplasma gondii: history and diagnostic test development

Toxoplasma gondiiis a protozoa that causes toxoplasmosis in people and other animals. It is considered one of the most common parasitic infections in the world due to its impressive range of hosts, widespread environmental contamination and the diverse means by which animals can be infected. Despite its ubiquity and numerous ongoing research efforts into both its basic biology and clinical management, many aspects of diagnosis and management of this disease are poorly understood. The range of diagnostic options that is available for veterinary diagnostic investigators are notably more limited than those available to medical diagnosticians, making accurate interpretation of each test result critical. The current review joins other reviews on the parasite with a particular emphasis on the history and continued development of diagnostic tests that are useful for veterinary diagnostic investigations. An understanding of the strengths and shortcomings of current diagnostic techniques will assist veterinary and public health officials in formulating effective treatment and control strategies in diverse animal populations.

Detection and survival of Toxoplasma gondii in milk and cheese from experimentally infected goats

The consumption of unpasteurized goat cheese and goat's milk has been suggested as a risk factor for toxoplasmosis in humans. In the present study, detection and survival of Toxoplasma gondii in milk and cheese was studied by bioassay in mice (milk) and in cats (cheese). Eight goats were inoculated orally with 300 to 10,000 oocysts of T. gondii strain TgGoatUS26. Milk samples were collected daily up to 30 days postinoculation and bioassayed in mice and cats. For mouse bioassay, 50 ml of milk samples were centrifuged, and the sediment was inoculated subcutaneously into mice. Mice were tested for T. gondii infection by seroconversion and by the demonstration of parasites. By mouse bioassay, T. gondii was detected in milk from all eight goats. The T. gondii excretion in milk was intermittent. For cat bioassay, 400 ml (100 ml or more from each goat) of milk from four goats from 6 to 27 days postinoculation were pooled daily, and cheese was made using rennin. Ten grams of cheese was fed daily to four cats, and cat feces were examined for oocyst shedding. One cat fed cheese shed oocysts 7 to 11 days after consuming cheese. Attempts were made to detect T. gondii DNA in milk of four goats; T. gondii was detected by PCR more consistently, but there was no correlation between detection of viable T. gondii by bioassay in mice and T. gondii DNA by PCR. Results indicate that T. gondii can be excreted in goat's milk and can survive in fresh cheese made by cold-enzyme treatment. To prevent transmission to humans or animals, milk should not be consumed raw. Raw fresh goat cheese made by cold-enzyme treatment of unpasteurized milk also should not be consumed.

Seroprevalence of Toxoplasma gondii infection in water buffaloes (Bubalus bubalis) in Veracruz State, Mexico and its association with climatic factors

Background

Infection with Toxoplasma gondii in water buffaloes (Bubalus bubalis) is of epidemiological importance because of the risk for transmission to humans. We sought to determine the seroprevalence of T. gondii infection in 339 water buffaloes in Veracruz State, Mexico using the modified agglutination test (MAT, cut off 1:25). Seroprevalence association with general characteristics of buffaloes and their environment was also investigated.

Results

Antibodies to T. gondii were found in 165 (48.7%) of the 339 buffaloes with MAT titers of 1:25 in 104, 1:50 in 52, and 1:100 in 9. Bivariate analysis showed that seroprevalence of T. gondii infection was similar in buffaloes regardless of their general characteristics i.e., age, sex, and breed. In contrast, the seroprevalence in buffaloes varied significantly with environmental characteristics including altitude, mean annual temperature, and mean annual rainfall of the municipalities studied. Multivariate analysis showed that T. gondii seropositivity in buffaloes was associated with a mean annual rainfall between 1266–1650 mm (OR = 1.84; 95% CI: 1.15-2.94; P = 0.01).

Conclusions

Results indicate that environmental characteristics may influence the seroprevalence of T. gondii infection in buffaloes. This is the first report on the seroprevalence of T. gondii infection in buffaloes in Mexico. Further research is needed to assess the risk for infection in humans associated with the ingestion of raw or undercooked meat from buffaloes infected with T. gondii.