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Plasmodium vivax Infection among Tourists to Puerto Vallarta and Acapulco, Mexico -- New Mexico, Texas

New Mexico. On January 17, 1985, a husband and wife from Santa Fe, New Mexico, flew to Puerto Vallarta, Mexico. They stayed at a beachfront resort hotel within the city limits of Puerto Vallarta for 4 days, after which they returned to the United States. On January 31, within a 12-hour period, the couple had onset of an illness characterized by fever, chills, drenching sweats, malaise, and headache. On February 2, when the wife sought medical attention, she had a fever of 38.9 C (102 F) and a mild tachycardia. Blood smears examined on the wife on February 3 and on the husband on February 4 revealed Plasmodium vivax. Both were successfully treated with chloroquine and primaquine. Interviews with the patients revealed no risk factors for acquiring malaria other than their recent vacation in Puerto Vallarta. Neither patient had traveled outside the United States in the past 5 years; neither had a history of blood transfusion or intravenous drug use. The couple did not leave the hotel grounds during their stay in Puerto Vallarta other than to travel to and from the airport. They had eaten their evening meal outdoors at the hotel on two occasions and had slept in a room with unscreened open windows. Both stated that they had been bitten by mosquitoes on multiple occasions.

Texas. On May 31, 1985, nine members of a family from San Antonio, Texas, flew to Acapulco, Mexico. They stayed in a rented villa situated on a cliff overlooking Acapulco Bay in a resort area 12 miles from the center of the city, where they remained until they returned to the United States on June 5. Between June 5 and June 17, six of the nine family members experienced febrile illnesses. On June 16, the first family member who became ill was diagnosed as having malaria after blood smears revealed P. vivax. Subsequently, blood smears on the other five ill family members also demonstrated P. vivax. All six were successfully treated with chloroquine and primaquine. Two of the three who have remained well have had negative blood smears. None of the family members had traveled outside the United States in the previous 5 years; none had any history of blood transfusion or intravenous drug use. The family had not left the villa other than to travel to and from downtown Acapulco and the airport. They ate their evening meals on an unscreened porch at the villa, where they experienced frequent mosquito bites.

Subsequently, CDC has been notified of four additional unrelated Texas residents who were infected by P. vivax during May and June in the same resort area as the family described above.

Reported by L Nims, MS, HR Landmann, MD, BM Greenfield, MD, D Gregory, MD, HC Anderson, MD, B Baker, MT, Santa Fe, L Davis, MD, Dept of Neurology, University of New Mexico School of Medicine; CM Sewell, DrPH, HF Hull, MD, State Epidemiologist, New Mexico Health and Environment Dept; D Allegra, MD, R Park, MD, W Dickenson, MT, Village Oak Hospital, F Buckwold, MD, Baptist Medical Center, San Antonio, T Gustafson, MD, J Perdue, CE Alexander, MD, State Epidemiologist, Texas Dept of Health; Malaria Br, Div of Parasitic Diseases, Center for Infectious Diseases, Div of Quarantine, Center for Prevention Svcs, CDC.

Editorial Note

Editorial Note: Transmission of P. vivax is reported to occur in the rural areas of both Jalisco and Guerrero, the states in which Puerto Vallarta and Acapulco are located (1). Current CDC recommendations indicate that there is no risk of malaria in major tourist resorts along the Pacific and Gulf of Mexico coasts (2), and the National Malaria Service of Mexico has not received any reports of malaria in Mexican or foreign tourists to these areas. However, these cases among U.S. travelers suggest that malaria can be transmitted in such areas, albeit rarely, and should be considered as a possible cause of a febrile illness in persons who have recently returned from resort vacations in Pacific coastal areas of Mexico.

While chemoprophylaxis is not recommended for travelers to these areas, physicians who advise patients before travel to Mexico should emphasize the importance of measures to reduce contact with mosquitoes during evening and nighttime hours, such as remaining in well-screened areas when possible, wearing protective clothes that cover most of the body, and using insect repellent on exposed areas of skin. Editorial Note: Photosensitivity of the skin refers to an abnormal reaction of the skin to light. This abnormal reaction results from exposure to certain therapeutic or chemical agents. Exposure may occur when the offending agent is either ingested or applied topically. The reaction occurs only after an exposed individual is subjected to ultraviolet or visible light. In most cases, the offending agents do not act as contact irritants by themselves; they are harmless to skin in the absence of exposure to light.

Photosensitivity reactions are classified as either photoallergic or phototoxic. Photoallergy involves the immune system. The offending agent, acting as a hapten, absorbs radiation, becomes activated, and reacts with protein(s) within the skin to form an antigen(s). This photoantigen is immunologically processed and manifests itself as an ordinary delayed hypersensitivity response. The patient with photoallergy has eczematous or papulovesicular eruptions.


  1. Subsecretaria de Servicios de Salud. Situacion epidemiologica del paludismo en Mexico, 1983. Epidemiologia Boletin, 1984;4:162-8.

  2. CDC. Health information for international travel 1984. Atlanta, Georgia: U.S. Department of Health and Human Services, PHS, Centers for Disease Control, Division of Quarantine, 1984; HHS publication no. (CDC)84-8280;11-58.

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