On January 27, 2012, a 45-year-old woman was admitted for hospitalization. She was from the Bacame Nuevo community, Etchojoa, Sonora, Mexico (Fig 1), a community with a desert climate, dedicated to agriculture and livestock. The patient had a history of outdoor activities and contact with cattle, rodents, dogs, and ticks. She presented with fever, arthralgias, diaphoresis, asthenia, adynamia, fatigue, headache, eye pain, tachycardia, abdominal pain, dyspnea, generalized diffuse rash, insomnia, nocturnal diaphoresis, daytime drowsiness, and character changes that included irritability. During January, she exhibited approximately five febrile episodes of greater than 39˚C and was symptomatically treated. She was diagnosed with a fever of unknown origin because she was serologically negative for other common diseases including leptospirosis, syphilis, and Lyme disease. The patient received treatment with beta-lactam antibiotics (amoxicillin for 15 days) without improvement in the symptoms. At her last evaluation, a blood sample was obtained, and spirochetes were observed by dark-field microscopy. She remained serologically negative to leptospirosis, syphilis, and Lyme-disease-causing spirochetes using commercially available diagnostic tests (Leptospira immunoglobulin G [IgG] immunoglobulin M [IgM] ELISA test [Diagnostic Automation, Woodland Hills, CA, USA], Bioelisa Syphilis 3.0 test [Biokit, Llic ¸à d'Amunt, Spain], and Lyme Disease IgG/IgM ELISA kit [Diagnostic Automation]). The patient was not hospitalized, but she was treated with doxycycline for 14 days and recovered. A retrospective evaluation of this patient's history and her clinical summary resulted with the suspicion of a tick-borne relapsing fever (TBRF). Borrelia sp. was suspected as the causative agent because of the proximity to the U.S. border and that cases of borreliosis have been identified in regions neighboring the Mexican state of Sonora, specifically Arizona and Texas [1, 2, 3, 4]. Also, during her examination, the patient reported that she found an insect bite on her leg. She had no history of traveling outside of the state of Sonora before the symptoms presented. The tick vectors of Borrelia turicatae and B. mazzottii have been collected along the Texas-Mexico border and into northern Mexico [5, 6];

The herbicides are used frequently to fight the proliferation of weeds. The use of herbicides correlates with an improvement in agricultural yield, but the harm to the health of human populations is well established and has been demonstrated in numerous scientific studies. In many developing countries, farmers build their own homes, and this, along with the application of herbicides in their fields, increases their exposure, through both contact with skin and respiration. It is scientifically proven that herbicides cause infertility, kidney problems, endocrine disruption, apoptosis, cytotoxicity, and neurotoxic effects. Such diseases impact the quality of those affected, and naturally the contaminated environment negatively affects human health. This chapter focuses on revising the most relevant studies regarding the health effects on agricultural workers living in rural environments due to herbicide contamination and how to sustain the herbicide use.

Background. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus that causes coronavirus disease 2019 (COVID-19). It is estimated that more than half of new infections are transmitted by asymptomatic people; therefore, the isolation of symptomatic people is not enough to control the spread of the disease. Methods. A total of 171 unvaccinated young adults (1835years) from Sonora, Mexico, who underwent a structured survey to identify prior COVID-19 infections, were included in this study. A qualitative determination of anti-SARS-CoV-2 antibodies in serum was performed by lateral flow immunoassay (Certum IgG/IgM Rapid Test cassette kit) and neutralizing antibodies were also determined (GenScript cPass assay). Results. A total of 36 people reported a history of COVID-19 infection, and 135 reported no history of COVID-19. In contrast, 49.6 (67/135) of individuals who had not reported a previous SARS-CoV-2 infection were seropositive to the rapid anti-SARS-CoV-2 antibody test, and 48.1 (65/135) of them had neutralizing antibodies. Conclusions. These results suggest that in young adults, SARS-CoV-2 infections could be asymptomatic in a high percentage of individuals, which could contribute in part to the slow control of the current pandemic due to the large number of asymptomatic cases that are contagious and that could be a silent spread of the virus.