Seroprevalence of Toxoplasma gondii in Slaughtered Pigs in Kiambu, Kenya

Round 1

Reviewer 1 Report

Comments:

What is the specificity and sensitivity of the test used? It would be convenient to mention it in the methodology.

It would be convenient to mention if cats were present in the porcine farms. Or the existence of noxious fauna that may be an accidental host harboring T. gondii.

In order to enrich the manuscript, it is suggested that a more extensive bibliographic search of worldwide distribution be carried out. For example, some articles that may be of interest to the authors are listed below:

Alvarado-Esquivel C, Romero-Salas D, García-Vázquez Z, Crivelli-Díaz M, Barrientos-Morales M, Lopez-de-Buen L, Dubey JP.  (2014). Seroprevalence and correlates of Toxoplasma gondii infection in domestic pigs in Veracruz State, Mexico (https://pubmed.ncbi.nlm.nih.gov/24510223/)

Flores, C. A., Jimenez, J., Gomez-Puerta, L. A., Palacios, C., O'Neal, S. E., Muro, C., Gonzalez, A. E., Gilman, R. H., & Calderón, M. (2021). Seroprevalence of Toxoplasma gondii in free-range pigs in northern Peru. Veterinary parasitology, regional studies and reports, 23, 100533. https://doi.org/10.1016/j.vprsr.2021.100533

Fredericks, J., Hill, D. E., Hawkins-Cooper, D. S., Fournet, V. M., Calero-Landa, J., Adams, B., Johnson, A., Barrow, M., Aquino, J., Mahmoud, T., Murphy, V., Barlow, A., Patel, P., George, M., Chehab, N., Kramer, M., & Bauer, N. E. (2021). Seroprevalence of toxoplasma gondii in market hogs collected from U.S. Slaughterhouses. The Journal of parasitology, 107(3), 404–410. https://doi.org/10.1645/20-142

 More specific comments can be found in the attachment.

Comments for author File: Comments.pdf

Author Response

Thank you for your review and constructive comments on our manuscript - our replies are in italics below

What is the specificity and sensitivity of the test used? It would be convenient to mention it in the methodology.

The ELISA is estimated to have a Sensitivity of 98.9% and Specificity of 92.7%, we have now included this in the manuscript at the end of section 2.3.

It would be convenient to mention if cats were present in the porcine farms. Or the existence of noxious fauna that may be an accidental host harboring T. gondii.

As we undertook this study within an abattoir setting we are unable to comment on the presence of cats on the farms, but we have highlighted this as a specific risk factor to look at in future work in the discussion (end of first paragraph pg 5). Thank you for this helpful suggestion.

In order to enrich the manuscript, it is suggested that a more extensive bibliographic search of worldwide distribution be carried out. For example, some articles that may be of interest to the authors are listed below:

Alvarado-Esquivel C, Romero-Salas D, García-Vázquez Z, Crivelli-Díaz M, Barrientos-Morales M, Lopez-de-Buen L, Dubey JP.  (2014). Seroprevalence and correlates of Toxoplasma gondii infection in domestic pigs in Veracruz State, Mexico (https://pubmed.ncbi.nlm.nih.gov/24510223/)

Flores, C. A., Jimenez, J., Gomez-Puerta, L. A., Palacios, C., O'Neal, S. E., Muro, C., Gonzalez, A. E., Gilman, R. H., & Calderón, M. (2021). Seroprevalence of Toxoplasma gondii in free-range pigs in northern Peru. Veterinary parasitology, regional studies and reports, 23, 100533. https://doi.org/10.1016/j.vprsr.2021.100533

Fredericks, J., Hill, D. E., Hawkins-Cooper, D. S., Fournet, V. M., Calero-Landa, J., Adams, B., Johnson, A., Barrow, M., Aquino, J., Mahmoud, T., Murphy, V., Barlow, A., Patel, P., George, M., Chehab, N., Kramer, M., & Bauer, N. E. (2021). Seroprevalence of toxoplasma gondii in market hogs collected from U.S. Slaughterhouses. The Journal of parasitology, 107(3), 404–410. https://doi.org/10.1645/20-142

Thank you for highlighting these interesting papers, we referenced a recent systematic review of porcine seroprevalence in our manuscript (5) and rather than then reference multiple single papers have expanded on the results of that systematic review in the introduction (pg 2, paragraph 2).

 More specific comments can be found in the attachment.

We thank the reviewer wholeheartedly for their through review and recommendations, as mentioned this is an early study to generate initial prevalence data on this important zoonoses but we would certainly like to expand upon the work and will incorporate their recommendations particularly on the presence of risk factors on farm such as cats.

Reviewer 2 Report

Thank you for this work on the seroprevalence of T. gondii in pigs in Kenya.  I agree that data from Africa are scarce, so it is always interesting to get such data.

 

In the introduction, the authors focused on the clinical relevance of T. gondii in humans, but T. gondii is also responsible for disease in pigs.  It may therefore be worth mentioning this.  Did you address this point in the questionnaire sent out to farmers?

It's also interesting to note that small farms are the most affected.  I agree that general farm hygiene and the way the animals are treated are probably to blame.  Have you been able to investigate this point in the field? If so, could you make some recommendations?

Have you investigated the presence of cats (or other T. gondii reservoirs) on farms?  I think this could be a risk factor.

Author Response

Thank you for considering our manuscript and your useful comments - our replies are in italics below

In the introduction, the authors focused on the clinical relevance of T. gondii in humans, but T. gondii is also responsible for disease in pigs.  It may therefore be worth mentioning this.  Did you address this point in the questionnaire sent out to farmers?

Thank you for this important observation which we had failed to raise in our manuscript. We did not address clinical signs in the questionnaire but have now included the following paragraph in the introduction (page 2 paragraph 1)

It's also interesting to note that small farms are the most affected.  I agree that general farm hygiene and the way the animals are treated are probably to blame.  Have you been able to investigate this point in the field? If so, could you make some recommendations?

We have been unable to run a farm-based study yet but this is our plan, we know from our experiences in small-holder farms in Kenya that biosecurity and hygiene are often poor and our colleagues at ILRI have developed a training manual that we will use to provide training and recommendations to farmers (https://www.ilri.org/knowledge/publications/integrated-training-manual-herd-health-and-biosecurity-smallholder-pig-value)

Have you investigated the presence of cats (or other T. gondii reservoirs) on farms?  I think this could be a risk factor.

Due to the abattoir setting of this study we were unable to investigate this important risk factor but it is certainly something we plan to investigate as a follow up, now mentioned in the discussion (end of paragraph 1 page 5),