What are the recommended travel vaccinations and malaria prophylaxis for an upcoming trip, and what tests are needed to evaluate irregular menstrual cycles?

Travel Vaccinations and Malaria Prophylaxis for Guatemala

For travel to Guatemala including Tikal, hepatitis A vaccination should be administered immediately regardless of departure timing, and chloroquine 500 mg weekly should be started 1-2 weeks before travel and continued for 4 weeks after return. 1

Hepatitis A Vaccination

Administer hepatitis A vaccine now, even if departure is imminent. The traditional recommendation to vaccinate 2-4 weeks before travel is overly conservative and should not delay vaccination. 2

• Seroconversion occurs rapidly: The majority of vaccinees develop protective antibodies within 2 weeks, with some achieving protection as early as 12 days post-vaccination. 2
• Hepatitis A has a long incubation period (average 28 days), providing a window for vaccine-induced immunity to develop even with late vaccination. 2
• Dosing schedule: Administer 1.0 mL (50 U for Vaqta or 1440 ELISA units for Havrix) intramuscularly now, with a booster dose at 6-12 months for long-term protection. 3, 4
• Efficacy: Seroconversion rates exceed 95% in healthy adults, with 90% achieving protection by day 15 and 97% by month 1. 4

Malaria Prophylaxis

Prescribe chloroquine phosphate 500 mg (300 mg base) weekly, starting 1-2 weeks before departure. 1

• Guatemala is a chloroquine-sensitive region west of the Panama Canal, where chloroquine-resistant P. falciparum is absent. 1
• Dosing regimen: Begin chloroquine 1-2 weeks before travel, continue weekly during travel, and maintain for 4 weeks after leaving the malarious area. 1, 5
• Alternative if chloroquine intolerance: Hydroxychloroquine may be better tolerated. 1
• Safety profile: Chloroquine has good tolerability with low cost, though pruritus can occur in some patients. 6

Personal Protection Measures (Essential Adjunct)

Mosquito avoidance is critical as no chemoprophylaxis provides 100% protection. 1

• Remain in well-screened areas between dusk and dawn when Anopheles mosquitoes feed. 1
• Use bed nets treated with permethrin (0.2 g/m² every 6 months). 5
• Apply DEET-containing repellent to exposed skin, following manufacturer's recommendations. 1, 5
• Wear long-sleeved clothing and long trousers after sunset. 5
• Treat clothing with permethrin for additional protection. 1

Critical Safety Information

• Seek immediate medical attention if fever, chills, or flu-like symptoms develop during travel or up to several months after return, as malaria symptoms can appear 8 days to months after exposure. 1
• Delayed diagnosis is life-threatening: Malaria mortality in the US is 0.3%, but early treatment is highly effective. 7
• Most US malaria cases occur in travelers who did not take prophylaxis: 71.7% of US residents diagnosed with malaria had not taken chemoprophylaxis. 7

Evaluation of Irregular Menstrual Cycles

Blood tests should be performed early in the menstrual cycle (days 1-5, up to day 14 if necessary) to evaluate for PCOS and thyroid dysfunction. The tests already requested (FBC, UEC, LFTs, TFTs, vitamin B12, beta-hCG) are appropriate initial screening.

Hormone Testing Timing

• FSH, LH, estradiol, and testosterone should be drawn during the early follicular phase (days 1-5) for accurate interpretation when evaluating PCOS.
• TSH and free T4 can be drawn at any time and are appropriate given symptoms of irregular periods and hair loss.
• Beta-hCG appropriately rules out pregnancy before further evaluation.

Additional Considerations

• Weight loss of 5-10% can restore ovulatory cycles in women with PCOS and obesity (current weight 99 kg).
• Repeat testing after return from travel if initial hormone panel suggests PCOS, as stress and travel can temporarily affect menstrual patterns.