US-Mexico binational COVID-19 cases in southern California border counties, California, February-June 2020

Background

COVID-19 has had a significant public health impact on both the United States and Mexico. Cross-border mobility between southern California and Mexico raises questions of transmission trends between these jurisdictions. The objective of this project was to describe binational cases amongst California US-Mexico border county COVID-19 cases and compare incidence trends to cross-border Mexico jurisdictions.

Methods

Interview data from persons with confirmed SARS-CoV-2 infections in San Diego County, CA and Imperial County, CA from February to June 2020 were reviewed for binational cases; demographics and connection to COVID-19 outbreaks were assessed. Graphs of COVID-19 incidence in San Diego County and Imperial County were compared to incidence graphs in cross-border Mexico jurisdictions of Tijuana and Mexicali.

Results

Persons with COVID-19 and a binational case were older, more likely to be Hispanic, and reside in a border ZIP code than those without. Binational cases were a small proportion and tracked with overall cases during the study period.

Conclusions

Binational cases had different trends than non-binational cases of SARS-CoV-2 in San Diego and Imperial counties from February to June 2020. Findings could inform SARS-CoV-2 mitigation strategies specific to the US-Mexico land border, particularly recommendations regarding cross-border land travel.

Acute viral hepatitis in the United States-Mexico border region: data from the Border Infectious Disease Surveillance (BIDS) Project, 2000-2009

Little is known about the characteristics of acute viral hepatitis cases in the United States (US)-Mexico border region. We analyzed characteristics of acute viral hepatitis cases collected from the Border Infectious Disease Surveillance Project from January 2000-December 2009. Over the study period, 1,437 acute hepatitis A, 311 acute hepatitis B, and 362 acute hepatitis C cases were reported from 5 Mexico and 2 US sites. Mexican hepatitis A cases most frequently reported close personal contact with a known case, whereas, US cases most often reported cross-border travel. Injection drug use was common among Mexican and US acute hepatitis B and C cases. Cross-border travel during the incubation period was common among acute viral hepatitis cases in both countries. Assiduous adherence to vaccination and prevention guidelines in the US is needed and strategic implementation of hepatitis vaccination and prevention programs south of the border should be considered.

Influenza-like illness surveillance on the California-Mexico border, 2004-2009

BACKGROUND

Since 2004, the Naval Health Research Center, with San Diego and Imperial counties, has collaborated with the US Centers for Disease Control and Prevention to conduct respiratory disease surveillance in the US-Mexico border region. In 2007, the Secretariat of Health, Mexico and the Institute of Public Health of Baja California joined the collaboration.

OBJECTIVES

The identification of circulating respiratory pathogens in respiratory specimens from patients with influenza-like illness (ILI).

METHODS

Demographic, symptom information and respiratory swabs were collected from enrollees who met the case definition for ILI. Specimens underwent PCR testing and culture in virology and bacteriology.

RESULTS

From 2004 through 2009, 1855 persons were sampled. Overall, 36% of the participants had a pathogen identified. The most frequent pathogen was influenza (25%), with those aged 6-15 years the most frequently affected. In April 2009, a young female participant from Imperial County, California, was among the first documented cases of 2009 H1N1. Additional pathogens included influenza B, adenovirus, parainfluenza virus, respiratory syncytial virus, enterovirus, herpes simplex virus, Streptococcus pneumoniae, and Streptococcus pyogenes.

CONCLUSIONS

The US-Mexico border is one of the busiest in the world, with a large number of daily crossings. Due to its traffic, this area is an ideal location for surveillance sites. We identified a pathogen in 36% of the specimens tested, with influenza A the most common pathogen. A number of other viral and bacterial respiratory pathogens were identified. An understanding of the incidence of respiratory pathogens in border populations is useful for development of regional vaccination and disease prevention responses.

Structure-function analysis of photosystem II subunit S (PsbS) in vivo

In land plants, photosystem II subunit S (PsbS) plays a key role in xanthophyll- and pH-dependent non-photochemical quenching (qE) of excess absorbed light energy. Arabidopsis thaliana (L.) Heynh. npq4 mutants are defective in the psbS gene and have impaired qE. Exactly how the PsbS protein is involved in qE is unclear, but it has been proposed that PsbS binds H⁺ and/or de-epoxidized xanthophylls in excess light as part of the qE mechanism. To identify amino acid residues that are important for PsbS function, we sequenced the psbS gene from eight npq4 point mutant alleles isolated by forward genetics screening, including two new alleles. In the four transmembrane helices of PsbS, several amino acid residues were found to affect the stability and/or function of the protein. By comparing the predicted amino acid sequences of PsbS from several plant species and studying the proposed topological structure of PsbS, eight possible H⁺-binding amino acid residues on the lumenal side of the protein were identified and then altered by site-directed mutagenesis in vitro. The mutant psbS genes were transformed into npq4-1, a psbS deletion mutant, to test the stability and function of the mutant PsbS proteins invivo. The results demonstrate that two conserved, protonatable amino acids, E122 and E226, are especially critical for the function of PsbS.

Nucleolar protein p120 contains an arginine-rich domain that binds to ribosomal RNA

Human proliferation-associated protein p120 has previously been shown to localize to the nucleolus, and several functional domains of p120 have been elucidated. By using a nitrocellulose filter binding assay and a Northwestern blotting procedure this study shows that recombinant p120 binds to an rRNA fragment in vitro with a dissociation constant of 4 nM. The specific RNA-binding region of p120 (residues 1-57) was identified with glutathione S-transferase-fused p120 deletion constructs and Northwestern blotting procedures. This RNA-binding region of p120, which includes the nucleolar localization signal of p120, is similar to the arginine-rich RNA-binding regions found in other RNA-binding proteins such as HIV Rev and Tat. Experiments in vivo with HeLa cell nucleolar extracts showed that p120 was associated with the 60-80S pre-ribosomal particles. This association is disrupted by treatment with either RNase A or buffer of high ionic strength. These results suggest that p120 might be involved in rRNA/ribosome maturation, consistent with the role of the yeast homologue Nop2p in rRNA biogenesis.

A baboon (Papio hamadryas) model of insulin-dependent diabetes

Over a period of four years, streptozocin has been used to induce diabetes in 10 baboons, all of whom are insulin dependent. We describe our experience with their husbandry, induction of diabetes, insulin therapy, metabolic control and growth rate. Streptozocin dosage of 60 mg/kg readily induces hyperglycemia with minimal hepatic or renal toxicity. Using a once daily injection of mixed short and intermediate acting insulins at a dosage of 2-4 U/kg, it is possible to maintain a degree of metabolic control similar to that attained in patients.

Clonidine hydrochloride--a safe and effective antihypertensive agent in pregnancy

A prospective, double-blind, randomized controlled trial was carried out, comparing alpha-methyldopa and clonidine hydrochloride in 100 pregnant women with hypertension. There was no difference in hypotensive effect or reported maternal side effects with either agent. There was one neonatal loss in each group (98% survival). Neither drug caused clinically significant hypotension nor rebound hypertension in the neonates. Clonidine hydrochloride, like methyldopa, appears to be a safe antihypertensive agent in pregnancy.

Hypertension in pregnancy. A study of 142 women presenting before 32 weeks' gestation

This study evaluates the outcome of 142 consecutive pregnancies in women in whom hypertension was diagnosed before 32 weeks' gestation and who were managed by a team comprising obstetricians, physicians and perinatologists. Arterial pressure was lowered to 140/90 mmHg or lower with clonidine hydrochloride or methyldopa therapy to which, in most cases, a vasodilator, hydralazine or diazoxide was added. The outcome of patients who were managed by the multidisciplinary team from the clinical onset of their disease was compared to the outcome of those who were transferred after the onset of hypertension from other centres. A greater perinatal mortality rate was found among the infants of patients with pre-eclampsia and patients with essential hypertension in pregnancy when the mothers were referred late for management. Reasons for the difference in pregnancy outcome are not clear. Possible explanations are discussed which emphasize the need for further study to establish optimal management of this common complication of pregnancy.

Effect of antihypertensive drugs on neonatal blood pressure

This study evaluates the perinatal outcome of infants born to ninety-five mothers with hypertension in pregnancy whose blood pressure was treated in a double blind trial comparing clonidine hydrochloride (C) and alpha-methyldopa (A). There were no fetal deaths and two neonatal deaths, giving a perinatal mortality of 2%. There was no significant difference between Groups C and A with regard to the gestation or weight at birth, incidence of intrauterine growth retardation, or condition at birth as judged by Apgar scores and acid-base status. No infant in either group developed significant hypotension or rebound hypertension. The blood pressure was not significantly different between Groups C and A, and controls. In each of these three groups there was a similar significant rise in systolic blood pressure with age.

High risk hypertensive pregnancies: maternal and foetal outcome

Two hundred and thirty-six pregnant women were referred for assessment and management of hypertension and/or renal disease. A Unit consisting of a physician, an obstetrician and a perinatologist jointly assessed each patient and advised on management. All patients were hospitalized and at bed rest. Drug therapy was clonidine hydrochloride or methyl dopa and in some patients a vasodilator was added. The decision to deliver was dictated by foetal maturity and wellbeing, in conjunction with maternal condition. There was no maternal mortality and the overall perinatal survival was 97%. The outcome of these pregnancies compares favourably with studies previously reported and reflect a successful approach to management of high risk hypertensive pregnancies.