December 14, 2000

Ninety-eight percent of all malaria cases investigated between 1994 and 1998 by the Houston Department of Health and Human Services (HDHHS) were reported in people who traveled to Central America or West Africa.
A majority of the cases of meningococcal disease in Houston occur during the winter months. St. Louis Encephalitis, with local outbreaks roughly every five years, has affected men disproportionately in the last 13 years.

The data represents infectious disease trends available online from HDHHS for use as a statistical resource by Houston researchers and the medical community. Epidemiology Notes, a quarterly newsletter offering five-year analytical reviews of various diseases, may be accessed at www.ci.houston.tx.us/departme/health/epi.htm.

“Epidemiology Notes represents the Houston Department of Health and Human Services effort to provide a quick and easy access to information on infectious diseases and reportable conditions specific to Houston,” said Dr. Raouf Arafat, HDHHS’ Bureau of Epidemiology Chief. “It is our way of providing feedback to the health care community and the general public and our tool for delivering current surveillance data available on communicable disease and reportable conditions in Houston.”

Newsletter editions currently online provide a local review of meningococcal disease, St. Louis Encephalitis, malaria, salmonella, hepatitis A and a report on the incidence of drownings and near-drownings. Salmonella and hepatitis A, the focus of the latest issues of the newsletter, are two of the most prevalent infectious diseases in Houston.

Salmonella ranked as the fifth most commonly-reported infectious disease between the years 1995 to 1999, behind hepatitis C, hepatitis B, hepatitis A and Shigellosis. During the period, health care providers reported to HDHHS a total of 1,259 salmonella cases, an average of 252 annually.

Salmonella is a bacterial infection causing fever, diarrhea and abdominal cramps. It usually lasts four to seven days, and most people recover without treatment. However, in some people, the diarrhea may be so severe that hospitalization is needed. In these patients, the infection may spread from the intestines to the blood stream, then to other body sites and can cause death if it is not promptly treated with antibiotics. The elderly, infants and those with impaired immune systems are more likely to have a severe illness.

In Houston, the disease follows a remarkably predictable pattern of yearly infection spiking sharply to anywhere from 30 to 50 cases between late June and October and declining abruptly by November.

Children under the age of five accounted for more than 44 percent of the reported salmonella cases, making them the most affected segment of the population. In terms of race and ethnicity, Hispanics had the highest number of cases at 36 percent, followed by whites, 28 percent; blacks, 19 percent; unknown 9 percent; and Asians and others, 8 percent.
Although Asians and other ethnic groups constituted a minority of just 8 percent of the cases, they had significantly higher rates of infection than all other individual groups because their population at risk was very small, less than 4 percent of the general Houston population.

A total of 1,577 cases of hepatitis A were reported to HDHHS between 1995 and 1999. Hepatitis A virus is one of several types of viruses that attack the liver. Ill people may experience jaundice, abdominal pain, dark urine, loss of appetite, fatigue, nausea, vomiting and fever.

The disease frequently passes from person to person by fecal-oral route. Hence, it is not surprising that it occurs frequently in children who may not have mastered the practice of regular hand washing. Activities thought to contribute to high frequencies of the disease in children also include sharing of food and prolonged and intimate contact during play.

Data reveals that more cases of hepatitis A occurred in children between the ages of 5 and 9 than in any other age group. Children in that age group represented 29.4 percent of the cases and were followed by those in the 10 to 14 age group, 15 percent, and 1 to 4, 10 percent.

The hepatitis A vaccine, licensed in the United States for use in adults and in children 2 years of age and older, and immune globulin prevent infection. Immune globulin is a preparation of antibodies that can be given before or after exposure to the virus for short-term protection against hepatitis A.   Immune globulin must be given within two weeks after exposure to hepatitis A virus for maximum protection.

The newsletter may also prove helpful to the public because it serves a review of the basics of the illnesses as well as preventive measures.